CA2432268C - Flux detector removal apparatus - Google Patents
Flux detector removal apparatus Download PDFInfo
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- CA2432268C CA2432268C CA002432268A CA2432268A CA2432268C CA 2432268 C CA2432268 C CA 2432268C CA 002432268 A CA002432268 A CA 002432268A CA 2432268 A CA2432268 A CA 2432268A CA 2432268 C CA2432268 C CA 2432268C
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- opening
- gripper
- main housing
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- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21C—NUCLEAR REACTORS
- G21C17/00—Monitoring; Testing ; Maintaining
- G21C17/10—Structural combination of fuel element, control rod, reactor core, or moderator structure with sensitive instruments, e.g. for measuring radioactivity, strain
- G21C17/108—Measuring reactor flux
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- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21C—NUCLEAR REACTORS
- G21C19/00—Arrangements for treating, for handling, or for facilitating the handling of, fuel or other materials which are used within the reactor, e.g. within its pressure vessel
- G21C19/20—Arrangements for introducing objects into the pressure vessel; Arrangements for handling objects within the pressure vessel; Arrangements for removing objects from the pressure vessel
- G21C19/207—Assembling, maintenance or repair of reactor components
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- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21C—NUCLEAR REACTORS
- G21C19/00—Arrangements for treating, for handling, or for facilitating the handling of, fuel or other materials which are used within the reactor, e.g. within its pressure vessel
- G21C19/32—Apparatus for removing radioactive objects or materials from the reactor discharge area, e.g. to a storage place; Apparatus for handling radioactive objects or materials within a storage place or removing them therefrom
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E30/00—Energy generation of nuclear origin
- Y02E30/30—Nuclear fission reactors
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- Engineering & Computer Science (AREA)
- Plasma & Fusion (AREA)
- General Engineering & Computer Science (AREA)
- High Energy & Nuclear Physics (AREA)
- Monitoring And Testing Of Nuclear Reactors (AREA)
Abstract
A flux detector removal tool for safely removing failed flux detectors from a CANDU.TM. type nuclear reactor. A housing operating under vacuum is provided. Within the housing there is a pair of cutting blades, a slideable gripper, and a pivot means for downwardly rotating the gripper. The gripper grasps and pulls a failed detector element within the housing and the element is cut. The pivot means rotates the gripper downward towards a withdrawal well. The gripper then releases the cut piece of detector into the withdrawal well, which is then transported under vacuum to a shielded flask.
Description
FLUX DETECTOR REMOVAL APPARATUS
FIELD OF THE INVENTION
The present invention relates to flux detector removal, and more particularly to a flux detector removal apparatus for nuclear reactors.
BACKGROUND OF THE INVENTION
Nuclear reactors require precise control systems in order to provide efficient performance and safe operation. Some control systems include neutron flux detectors (NFD) to detect neutron release as a measure of the reaction rate and reactor conditions. Some reactors, such as CANDUTM type reactors, are equipped with straight individually replaceable (SIR) flux detector assemblies.
CANDUTM type reactors can include both horizontal and vertical SIR
flux detectors. These detectors are self-powered and provide signals that are used as inputs to the first and second shutdown systems, and data to the reactor regulating system to control reactivity. NFD units are composed of a thimble assembly, a locator and the flux detector assembly. The units are vertically and horizontally positioned in the reactor core. The vertical units are located beneath the thick tread shield plates in the reactivity mechanism service area and the horizontal units are within the reactor vault. Referring now to FIG. 1, typical locations of horizontal and vertical SIR flux detectors in a CANDUTM type reactor will be described. A nuclear reactor is indicated generally by reference 200. A reactor vault 202 houses the reactor 200. The reactor 200 comprises a shield tank 204, heavy water moderator 205, and reactivity mechanism (R/M) deck structure 206. A typical reactivity control unit mechanism is indicated by reference 207. The deck structure 206 forms an upper accessible area indicated by reference 208. The reactor 200 also has a light water shield 210 and shielded tank extension 212. Horizontal flux detector units 214 and vertical flux detector units 216 are located about the reactor and are fixed on the reactor side by a locator 218.
FIELD OF THE INVENTION
The present invention relates to flux detector removal, and more particularly to a flux detector removal apparatus for nuclear reactors.
BACKGROUND OF THE INVENTION
Nuclear reactors require precise control systems in order to provide efficient performance and safe operation. Some control systems include neutron flux detectors (NFD) to detect neutron release as a measure of the reaction rate and reactor conditions. Some reactors, such as CANDUTM type reactors, are equipped with straight individually replaceable (SIR) flux detector assemblies.
CANDUTM type reactors can include both horizontal and vertical SIR
flux detectors. These detectors are self-powered and provide signals that are used as inputs to the first and second shutdown systems, and data to the reactor regulating system to control reactivity. NFD units are composed of a thimble assembly, a locator and the flux detector assembly. The units are vertically and horizontally positioned in the reactor core. The vertical units are located beneath the thick tread shield plates in the reactivity mechanism service area and the horizontal units are within the reactor vault. Referring now to FIG. 1, typical locations of horizontal and vertical SIR flux detectors in a CANDUTM type reactor will be described. A nuclear reactor is indicated generally by reference 200. A reactor vault 202 houses the reactor 200. The reactor 200 comprises a shield tank 204, heavy water moderator 205, and reactivity mechanism (R/M) deck structure 206. A typical reactivity control unit mechanism is indicated by reference 207. The deck structure 206 forms an upper accessible area indicated by reference 208. The reactor 200 also has a light water shield 210 and shielded tank extension 212. Horizontal flux detector units 214 and vertical flux detector units 216 are located about the reactor and are fixed on the reactor side by a locator 218.
At each NFD unit location, the conventional detector guide tube is equipped with a cluster of small-bore well tubes, fitted with SIR flux detectors.
Referring now to FIG. 2, a typical vertical flux detector unit will be described.
A vertical flux detector unit 216 is installed below deck shield tread plate 220.
The detector 216 comprises a detector assembly 222 and a thimble assembly 224 having thimble bellows 225. The detector assembly 222 includes detector lead cable 226, LemoTM connector 228, and a helium cover gas supply 230. The detector assembly 222 is located below the shield plate 232 and is partially housed in a shielding sleeve 234 embedded in deck concrete 236. A thimble is indicated by reference 238. A detector well cluster is indicated by reference 240.
Referring now to FIG. 3, a typical horizontal flux detector unit will be described. A horizontal flux detector unit 214 comprises a detector assembly 222 and thimble assembly 224. A protective cover 242 surrounds the assemblies 222 and 224. A guide tube assembly is indicated by reference 244. The detector unit is received in the reactor 200 by a shield tank nozzle 246 in the shield tank wall 248.
One known detector arrangement used in CANDIJTM type reactors, for example, has twenty-three vertical and fourteen horizontal SIR flux detector assemblies installed in a single reactor unit. Each assembly provides twelve well tubes in which the detector elements are inserted. The assemblies may contain up to nine operating flux detector elements, one per well tube, that can be removed and replaced in situ individually. To facilitate this operation, the individual detector well tubes and LemoTM connectors are readily accessible and clearly identifiable, with the assembly housing cover removed.
Each flux detector element comprises a lead wire and a lead cable having an emitter core. Vertical and horizontal detector elements are installed into the detector wells such that the emitter portion of the detectors are positioned at the required locations in the reactor core. The emitter portion of the detectors are 0.118 inches (3 mm) in diameter and 33.75 inches long and are attached to a lead cable which is 0.04 inches (1 mm) in diameter and varies in length from 275 to 432 inches depending on the location. The lead wire is typically 12 to 14 inches in length. The vertical detector elements are lnconelTM sheathed co-axial emitter and lead assemblies. Horizontal detector elements are platinum clad co-axial emitter and lnconelTM lead assemblies. Referring now to FIGS. 4A to 4C, a typical SIR flux detector element will be described. A detector element comprises a lead wire 250, lead cable 252 and emitter core 254. A sheath 255 surrounds the detector.
The emitter portion of the detector has a magnesium oxide core 256. In horizontal detectors, the detector element also has an emitter cladding 258.
The lead wire 252 typically has a LemoTM connector 228 and crimp stops 260.
Detector signai deterioration due to the accumulated effects of irradiation affects neutron SIR flux detector elements. This deterioration process during the life of the reactors will lead to SIR flux detector element failures. Other causes of detector failures are manufacturing deficiencies and loss of the flux detector protective environment.
Most reactivity mechanism maintenance programs require failed detector elements to be removed from the reactor. Removal of failed flux detectors requires dedicated flasking equipment because detector elements become radioactive as a result of exposure within the reactor. Also, irradiation of the flux detectors causes radiation hardening of the detector elements. Attempts to remove detectors by winding the irradiated lead cable onto a spool results in a high frequency of cable breaking. Thus, a system for removing irradiated cable in one straight piece using shielded in-station main reactivity mechanism flasks rather than coiling was developed. This system requires the installation of a temporary containment barrier, extensive work and time in a radiation area, and the use of a large and heavy in-station reactivity mechanism flask. A typical in-station reactivity mechanism flask is a shielded flask approximately 33 feet long and 55,000 lb in weight. In addition, in some CANDUTM type reactors, the size of the flask prevents the _4_ used of this system of horizontal and vertical SIR flux detectors in all locations.
It is desirable to have a system for removing and flasking horizontal and vertical SIR fiux detectors that substantially reduces the radiation dose by minimizing the time and work required as well as eliminating the complex procedures and the use of large and heavy equipment. The present inventor has developed a known robotic apparatus to remove the detector from the reactor inch by inch, cutting the detector into 1 inch segments, and transferring these segments to a shielded flask.
This system for individually removing vertical and horizontal SIR flux detectors from reactors consists of: a portable light weight housing that contains robotics and video components, a pneumatic and an electronic control panel, a video monitor, a vacuum unit, flask assembly and associated equipment. The system is portable and is designed to be stored or transported to the flux detector removal sites on a dedicated trolley.
Referring now to FIG. 5, a typical arrangement of the system in transit to a flux detector removal site and the location of its component when coupled to a reactor will be described. The system is stored and transported on trolley indicated generally by reference 302. The trolley has a retractable tow bracket 304, a flask gripper plug 306, a lifting lug 308, a flask assembly 309, a vacuum unit 310, a vacuum hose 312, and a tracking sensor 313. In transit, the trolley stores a pneumatic control panel 314, a electronic control panei 316, and a robotic apparatus 318. In operation, the apparatus 318 is coupled to a reactor 200, typically using a spacing element 320. A pneumatic harness 322 and control cable 324 are connected to the pneumatic control panel 314 and electronic control panel 316. A video monitor 326 provides for monitoring of the removal operation by an operator at a remote location.
The design of the system utilizes a concept whereby the detector lead of an irradiated flux detector element is withdrawn from its position in the well tube by a remotely operated robot. The apparatus in the robotics housing are pneumatically operated to clasp, pull, hold, cut and drop off 1 inch pieces of an irradiated SIR flux detector in a repetitive manner. In a typical cycle, the gripper moves forward from its home position, clasps the flux detector element that is held by a set of spring loaded non release clamps and pulls the element out 1 inch. One of the redundant cutters moves forward from its home position and cuts off the detector element. The gripper transports the piece to an ejection port and releases it to be sucked into the vacuum hose.
The 1 inch piece of detector element is then transported by the vacuum system into a waste container located in a dedicated flask. Tracking of the 1 inch piece during flasking is provided to ensure that the piece of detector was transferred into the shielded flask. A waste container may be transferred using either underwater or dry transfer flasks for waste container temporary or permanent storage. The waste container may be removed from the flask underwater for in-bay storage at an irradiated fuel bay within the reactor facility. Alternatively, the waste container may be transferred to a road transportable flask for transportation to, for example, a permanent in-ground disposal site.
It is desirable to reduce the risk that a cut piece of failed detector element may be dropped or misdirected within the robotic housing during the removal operation, requiring a technician or other personnel to remove the flux detector segment. The removal of a dropped piece of detector results in significant downtime and unnecessarily exposes personnel to the radiation emitted by the detector element.
SUMMARY OF THE INVENTION
The present invention is a flux detector removal apparatus for use in nuclear reactors that reduces the risk that a cut piece of detector will be dropped or misdirected.
In accordance with one aspect of the present invention, there is provided an apparatus for safely removing flux detectors, comprising: a main housing defining a first opening and a second opening; a cutting blade pivotabiy attached to the interior of said main housing, said blade forming a bite around at least a portion of said first opening; a gripper; and pivot means for pivoting said gripper about a second axis perpendicular to said first opening.
In accordance with another aspect of the present invention, there is provided an apparatus for safely removing flux detectors, comprising: a main housing defining a first opening and a second opening; a cutting blade pivotably attached to the interior of said main housing, said blade forming a bite around at least a portion of said first opening; a gripper; and first slide means coupling said gripper to the interior of said main housing for providing movement along a first axis coaxial with said first opening.
In accordance with a further aspect of the present invention, there is provided an apparatus for safely removing flux detectors, comprising: a main housing defining a first opening and a second opening; a cutting blade pivotably attached to the interior of said main housing, said blade forming a bite around at least a portion of said first opening; a gripper; and an element entry housing defining a channel and an interior lateral notch, said element entry housing being at least partially received in said main housing, said channel and said lateral notch being in communication with said first opening.
In accordance with yet another aspect of thepresent invention, there is provided an apparatus for safely removing flux detectors, comprising: a main housing defining a first opening and a second opening; a cutting blade pivotably attached to the interior of said main housing, said blade forming a bite around at least a portion of said first opening; a locking gate including a pair of elongate locking flags having a first end and a second end, and biasing means for rearwardly biased attachment of the first end of each of said flags within said housing; and a gripper attached to the interior of said main housing.
Other aspects and features of the present invention will become apparent to those ordinarily skilled in the art upon review of the following description of specific embodiments of the invention in conjunction with the accompanying figures.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will be further understood from reference to the following drawings in which:
FIG. 1 is a cut-away illustrating typical locations of flux detector units in a CANDUTM type reactor;
FIG. 2 is a cut-away illustrating a typical vertical flux detector unit arrangement;
FIG. 3 is a cut-away illustrating a typical horizontal flux detector unit arrangement;
FIG. 4A is a partial side view cut-away illustrating portions of a typical SIR flux detector element;
FIG. 4B is an end view cut-away illustrating typical SIR flux detector element;
FIG. 4C is a side view cut-away illustrating typical SIR flux detector element, FIG. 5 is a side view illustrating the general arrangement of a typical SIR flux detector removai systems;
FIG. 6 is a right side view of one embodiment of a flux detector removal apparatus according to the present invention;
FIG. 7 is an exploded partial front view of FIG. 6 showing the gripper assembly attached to the tie tube end plate;
' U -F1G. 8 is an exploded partial front view of FIG. 7 with the tie tube end plate removed;
FIG. 9 is an exploded partial front view of FIG. 6 showing the cutting assembly;
FIG. 10A is an exploded partiai top view of FIG. 6 showing the cutting and gripper assemblies;
FIG. 10B is an exploded partial top view of the FIG. 10A showing the locking gate;
FIG. 10C is an exploded perspective view of FIG. 6 showing the gripper in home position;
FIG. 10D is an exploded perspective view of FIG. 6 showing the gripper in forward, downwardly rotated position;
FIG. 11 is a side view of a shielded flask coupled to the flux detector removal apparatus with a nozzle plug received therein;
FIG. 12 is a side view of a shielded flask coupled to the flux detector removal tool with a gripper plug received therein;
FIG. 13A is a side view of a waste container using in the apparatus of FIG. 6;
FIG. 13B is an exploded side view of FIG. 13A showing the basket received in the waste container;
FIG. 13C is a top view of FIG. 13A;
FIG. 14 is a side view of a second embodiment of the shielded flask coupled to the flux detector removal tool with a nozzle plug received therein;
and FIG. 15 is a side view of the apparatus of FIG. 6 configured for vertical SIR flux detector removal and coupled to a reactor.
DETAILED DESCRIPTION OF THE DRAWINGS
Referring now to FIGS. 6 to 10D, a flux detector removal apparatus in accordance with one embodiment of the present invention is indicated generally at 10. The apparatus 10 comprises a housing indicated generally by reference 12, a gripper assembly indicated generally by reference 14, and a cutting assembly indicated generally by reference 16. As will be described in more detail below, the apparatus 10 is used in a flux detector removal system that provides a sealed system for the removal of flux detectors from a CANDUTM type nuclear reactor.
As shown in FIG. 6, the housing 12 comprises a main housing 18, an element entry housing 20, a cover plate 22, withdrawal wells 24, a vacuum tube adapter 25, and a transparent cover 26. In the shown configuration, the apparatus 10 is configured for horizontal SIR flux detector removal. If vertical SIR flux detector removal is desired, the cover plate 22 is removed from the shown position. The cover plate 22 is attached to the main housing 18 using suitable fasteners that provide for easy removal. The adapter 25 is then removed from the shown position. The adapter 25 is also attached to the main housing 18 using suitable fasteners that provide for easy removal. The vacuum tube adapter 25 is then installed in the position formerly occupied by the cover plate 22. The cover plate 22 is then installed in the position formerly occupied by the adapter 25. The switching of the cover plate 22 and the vacuum tube adapter 25 allows for easy re-configuration of the apparatus 10 between horizontal and vertical removal configurations. The operation of the apparatus 10 will now be described in more detail with respect to the shown horizontal removal configuration. For the vertical removal configuration, this description should be read with appropriate changes to directional and positional references according to the vertical removal configuration described above.
As shown in FIG.6, the main housing 18 has an opening in its rear wall which is in communication with a channel in the element entry housing 20.
Flux detectors which are to be removed from the reactor enter the main housing 18 via the element entry channel and rear opening. 0-rings are provided where the main housing 18 contacts the element entry housing 20, the cover plate 22, and the adapter 25 to provide a seal. The transparent cover 26 is attached to the main housing 18 using suitable fasteners that allow the cover 26 to be removed if access to the internal components of the apparatus 10 is desired, for example, to repair or replace components. Tie tubes 28 are mounted to the main housing 18 at one end and are secured at the opposite end by a tie tube end plate 30 (see FIG. 7 for a front plan view of the tie end plate 30). As shown in FIG. 6, tie tubes 28 provide a support structure within the housing 12 on which components of the gripper assembly 14 and cutting assembly 16 can be mounted. In most applications, shielding of the apparatus 10 is required to prevent or minimize the exposure of personnel to the radiation emitted from detector elements received within the housing 12.
As shown in FIG.9, camera housing 87 is attached to the main housing 18 to provide monitoring capabilities. A camera 88 and a light 90, for example, a 6V 10W Quartz light from Phillips, allow the removal operation to be remotely monitored by a technician. A paper gasket is provided between the camera housing 87 and the main housing 18 to create a seal. 0-rings or other sealant means are provided around the camera 88 and light 90 to seal the camera housing 87.
As shown in FIG. 8, the gripper assembly 14 comprises a gripper 32, a transition adapter 34 (not shown), a gripper slide assembly 36, an actuator slide assembly 38, and a rotary actuator 40. As shown in FIG. 10C, the gripper 32 is preferably a parallel jaw gripper, for example, a 190 Series gripper from PHD, Inc.. The gripper 32 has a jaw, indicated generally by reference 112 (see FIG. 1 0B for enlarged view), comprising a pair of elongate jaw members 114 (see FIG. 10B for enlarged view) attached to the gripper 32 on the end nearest the cutting assembly 16. As shown in FIG. 10C, the jaw 112 and jaw members 114 are coaxial with the element entry channel 55 so that the gripper 32 can easily grasp a detector element received within the housing 12. The jaw members 114 are each capable of lateral movement providing for the gripper 32 to grasp a detector element. Typically both jaw members 114 have coordinated movement, moving either towards the bite to grasp a detector element or away from the bite to release a detector element.
If desired, the jaw members 114 may be operated differently. For example, one jaw member 114 may be stationary while the second jaw member 114 moves between a locked (grasping) and unlocked (releasing) position.
Parallel jaw grippers are preferable because of their compact size, making it easier to handle small parts in the confined working area of the housing 12.
Other types of grippers may be used. If desired, the gripper jaw may be customized to more easily grip the flux detector elements. As shown in FIG.
10C, The gripper 32 is operably connected to the gripper slide assembly 36 by the transition adapter 34. The gripper slide assembly 36 provides the gripper 32 with independent longitudinal movement within the housing 12.
The gripper slide assembly 36 is preferably a cantilever type slide, for example, a Series SB slide from PHD, Inc.. As shown in FIG.8, mounting plate 41, gripper slide bracket 42 and suitable fasteners couple the slide assembly 36 to the rotary actuator 40.
As shown in FIG. 8, the rotary actuator 40 may be a single vane or double vane unit, for example, the actuator may be a PV Series rotary actuator from Schrader Bellows. The rotator actuator 40 includes a roll pin 45 that provides pivotal or rotary movement to the gripper 32. As shown in FIG. 6, a mounting plate 44, mounting brackets 48 attached on the lower tie tubes 28, and suitable fasteners couple the rotator actuator 40 to the actuator slide assembly 38. The actuator slide assembly 38 is preferably a saddle slide, for example, an M Series saddle slide by PHD, Inc.. The actuator slide assembly 38 provides the gripper assembly 14 with longitudinal movement within the housing 12.
As shown in FIGS. 9 and 10A, the cutting assembly 16 comprises a pair of redundant cutters including an upper moving blade 50 (see FIG. 10C
for enlarged view), a lower stationary blade 52 (see FIG. 10C for enlarged view), a cutter slide assembly 54, and a cylinder 58. During normal operation, only one of the two cutters is used. Redundant cutters are provided so that a secondary or backup cutter is available should the first cutter break down during a removal operation. As shown in FIG. 10C, the cutting assembly 16 also comprises a locking gate 56 received within the element entry channel 55 of the element entry housing 20. As shown in FIG.
10B, the locking gate 56 comprises a pair of locking flags 60, a pair of dowel pins 61, and a pair of torsion springs 62). The dowel pins 61 attach the locking flags 60 to the element entry channel and couple the flags 60 to the torsion springs 62. The torsion springs 62 apply a rearwardly biasing force against the locking flags 60 so that the flags 60 are normally in a closed position.
As shown in FIG. 10A, the cutter slide assembly 54 is attached to the rear wall of the main housing 18 using suitable fasteners. Preferably, a paper gasket is located between the slide assembly 54 and the rear wall of the main housing 18. The cutter slide assembly 54 is preferably a cantilever type slide, for example, a Series SB slide from PHD, Inc.. The slide assemblies 54 provide for lateral movement of the redundant cutters within the housing 12.
In their home position, the cutters are removed from working area where a detector would normally be present during operation. When the cutters are in their forward position, the bite created by the cutting blades 50 and 52 would surround a detector from one side.
As shown in FIG. 10A, the lower stationary blade 52 is attached to slide assembly 54 by means of suitable fasteners. Upper moving blade 50 is pivotably mounted to lower blade 52 in offsetting relation using a suitable fastener near the bite. Cylinder 58 couples upper blade 50 to lower blade 52 at the opposite end nearest the transparent cover 26. The pivotable connection of the upper blade 50 to the lower blade 52 provides for the upper blade to rotate about a point 63. The cylinder 58 is preferably a pneumatic cylinder, for example, a CDR-24-1 Model cylinder by Clippard Instrument Laboratory, Inc. Upward movement of the cylinder 58 causes the downward rotation of the upper moving blade 50, resulting in the closure of the cutter's bite. If a detector element is held in locked position within the locking gate 56, the closure of the bite will severe the detector element.
As shown in FIG. 10B, the locking gate 56 is used to hold the flux detector to be cut in locked position. As discussed previously, torsion springs 62 apply a rearwardly biasing force against the locking flags 60 so that the flags 60 desire to be in closed position. As shown in FIG. 10C, the element entry housing 20 defines an element entry channel 55 and an interior lateral notch 57 with the element entry channel 55 and the lateral notch 57 being in communication with the opening (not shown) of the element entry housing 20.
In closed position, the mating surfaces of the locking flags 60 meet and the element entry channel 55 is closed. When a flux detector element is within the element entry channel 55, the rearwardly biasing force of the torsion springs 62 holds or locks the detector element so that it cannot be easily moved. This locked position is advantageous for the cutting of the flux detector element.
Referring now to FIGS. 11 and 12, the flux detector removal system in which the apparatus 10 is used will be described. A first vacuum hose (not shown) couples the vacuum outlet adapter 25 (not shown) of the apparatus 10 (not shown) to a shielded flask 64 wherein the cut pieces of detector element are temporarily stored. The shielded flask 64 is lined with lead to prevent or minimize the exposure of personnel to the radiation emitted from the detector element. The flask 64 is relatively small and is designed to be easily handled in the reactor vault for horizontal flux detectors removal or over the reactor deck for vertical removals. Inner wall 66 of the flask 64 defines a holding cavity. An outlet pipe 68 having outlet adapter 74 is located at the bottom of the holding cavity. A support bracket 72 is attached to inner wall 66. Waste container 70 is received within the shielded flask 64 and is supported by the bracket 72. Waste container 70 provides temporary storage of cut flux detector elements.
During the cutting operation, vacuum nozzle plug 76 having a downwardly projecting inlet pipe 78 having inlet adapter 73 is also received within the flask 64. Upper surface 75 of flask 64 meets lower surface 77 of the vacuum nozzle plug 76 flushly, providing a seal. The first vacuum hose couples adapter 25 (not shown) to inlet adapter 73. A second vacuum hose (not shown) couples outlet adapter 74 to a vacuum unit (not shown) to provide suction to the system. This vacuum system provides a sealed environment for the removal and flasking operations. The sealed environment is important in protecting personnel from the radiation hazards created by the removal and disposal of irradiated flux detectors.
Referring now to FIGS. 13A to 13C, the waste container will be described in more detail. The waste container 70 comprises a perforated base 79, an inner basket 81, a coupling 80 and a self-closing lid 82. The lid 82 comprises a pair of mating panels 84. Each panel has an upwardly biasing spring 86, a shaft 92, cotter pins 94 and a bushing 96. Each spring 86 is received in channel defined in the side of the coupling 80. Shaft 92 and pins 94 secure the spring 86 in the channel. Bushing 96 protects the portion of shaft 92 received in the channel. When the vacuum nozzle plug 76(not shown) is not received within the flask 64, the upward bias of the springs 86 maintains the panels 84 in closed position. As shown in FIG. 11, when the vacuum nozzle plug 76 is received within the flask 64, the inlet pipe 78 exerts a downward force on the panels 84 counteracting the upward bias of the springs 86 and opening the panels 84 to receive the inlet pipe 78. The upward bias of the springs 86 causes the panels to close around pipe 78.
When the nozzle plug 76 is removed, the springs 86 quickly re-close the panels 84, sealing the waste container 70.
As shown in FIG. 12, during removal, a gripper plug 100 is received within the flask 64. The gripper plug 100 has latches which releasably engage the coupling 80 allowing the waste container to be remotely lifted and transported to a desired location for disposal, storage, or transportation to an off-site storage location.
Referring now to FIG. 14, another embodiment of the shielded flask and nozzle plug will be described. In the shown embodiment, an outlet pipe 69 is located in the nozzle plug 76 rather than the shielded flask 64. When the plug 76 is received in the flask 64, the outlet pipe 69 opens into the holding cavity and is located near the inner wall 66 to accommodate inlet nozzle 78. The inlet nozzle 78 has a lower vertical region and upper inclined region. The lower vertical region enters the waste container 70 as previously described. Instead of a support bracket, the waste container 70 rests on the bottom of the holding cavity.
Referring now to FIG. 15, the vertical removal configuration will be briefly described. In the vertical removal configuration, the cover plate 22 (not shown) and the vacuum tube adapter 25 (not shown) are switched as described above. In the shown embodiment, the apparatus 10 is contained within a shielding 98 which prevents or minimizes the exposure of personnel to radiation emitted from detector elements received within the housing 12 (not shown). The shielding 98 is preferably lead lined. A first vacuum hose 102 connects the apparatus 10 to the shielded flash 64. Pneumatic cables 104 and control cables 106 provide a communication pathway between the air supply and apparatus control system respectively. Differences in the environment surrounding vertical SIR flux detector assembly ports require the use of a shielded pedestal 108 to provide clearance from reactivity mechanism components in the area, for example, shielding blocks. The pedestal 108 couples directly to the element entry housing 20 on one side. A
pedestal adapter 110 couples the opposite end of the pedestal 108 to the reactor.
In operation, the flux detector removal system is moved to the location of a horizontal or vertical SIR flux detector assembly port where it is desired to remove one or more failed flux detector elements. The protective cap covering the assembly port is removed by a remotely operated robot thereby exposing the flux detector(s) of interest. The detector lead of the element to be removed is then withdrawn from its position in the well tube. The apparatus 10 is then coupled to the assembly port of the reactor at the element entry housing 20. The apparatus 10 may be connected directly or using a spacing element between the element entry housing 20 and the reactor. When the apparatus 10 is connected to the reactor, the detector lead wire passes through the entry channel of the element entry housing 20 and forces open the normally closed locking flags 60 of the locking gate 56. The lead wire of the detector is now within the main housing 18. The torsion springs 62 impart a rearwardly biasing force on the locking flags 60 causing them to close on the detector lead wire, holding it in a locked position.
The gripper 32 then moves forward from its home position and grasps the detector. The gripper 32 then moves backwards to its home position, thereby pulling the detector further within the main housing 18. The gripper 32 preferably pulls the detector within the housing 18 such that a 1 inch piece of detector may be cut, although a longer or shorter piece of detector may be cut off. One of the redundant cutters will now cut the 1 inch piece of detector as will be described below. Either cutter may be used. The operator typically selects a single cutter to be used for the duration of a detector removal campaign, although the operator may switch between cutters if desired.
In normal position, the upper moving blade 50 is in its upper position with respect to the lower stationary blade 52, forming a bite. If the upper blade 50 is not in its normal upper position, it is moved to its upper position.
One of the redundant cutters then moves forward from its home position towards the detector now received within the element entry channel such that the detector is within the bite formed by the upper blade 50 and lower blade 52. The upper blade 50 is then moved to its lower position, closing the bite and severing a 1 inch piece of detector. The upper blade 50 is then moved to its normal upper position, and the cutter is moved back to its home position.
The gripper 32 now holds the 1 inch cut piece of detector which now requires disposal in the withdrawal well 24 of the main housing 18. The gripper 32 is then rotated or pivoted downwards so that the 1 inch cut piece within the gripper jaw is at a modest height above the withdrawal well 24 (see FIG. 10D). The gripper 32 then releases the 1 inch cut piece into the well 24, which is then transported via the first vacuum hose to the water container 70 in the shielded flask 64 by the suction provided by the vacuum unit. The cut piece is monitored within the main housing 18 by the video camera 88 assisted by the light 90. The cut piece is also tracked by a second video camera (not shown) during flasking to ensure that it is transferred into the shielded flask 64. The second camera is located at the flasking station by the canister entrance. The system operates in a repetitive manner, gripping, cutting, and disposing of 1 inch cut pieces until the entire detector element to be removed has been cut and transferred to the waste container 70.
The waste container 70 may be transferred from the flask 64 using either underwater or dry transfer flasks for waste container temporary or permanent storage. The waste container 70 may be removed from the flask underwater for in-bay storage at an irradiated fuel bay within the reactor facility. Alternatively, the waste container 70 may be transferred to a road transportable flask for transportation to, for example, a permanent in-ground disposal site.
During the operation of the system, the actions in the housing 12 are observed via a closed circuit television. The operator is located at a remote location 50 feet away from the flux detector removal site and controls the apparatus 10 with a series of push buttons switches or preferably a touch screen. A touch screen may provide graphical representation of each step of the process. The touch screen may also list available options in any situation as the apparatus 10 progresses through its cycle. Thus, in the event of a stoppage the touch screen could be made to show what options are available to the operator, assisting in the decision making process.
The system can be made run on a single mode or in a repeat (automatic) mode and will stop if any action is not completed. The speed of the removal operation is adjustable. Emergency stop and override functions are provided in case of abnormal operation. The programmer and the control components are situated at the operator remote location. In case of need, power valves can be manually actuated to operate the apparatus 10 remotely.
The system requires air pressure (100 psi) and 120 volt at 60 Hz, to function normally, however, as all electrical components operate on 24 volts DC, a back up battery pack could be used to maximize reliability.
The system's programmable logic controller (PLC), is a stepping controller which will not allow the operation of the system to continue without specific conditions being met each step of the flux detector removal and flasking process. Each component of the apparatus 10 has a sensor at its end of travel, which changes stated when the action is completed. The PLC
reviews the status of the system and will only proceed to the next step of the process if all conditions are met. If abnormal conditions are found, the system stops its operation and waits for operator input.
An important feature of the system is the capability of recognizing the presence of the flux detector element in the detector entry channel of the robotics housing. A sensor signals which portion of detector element is in the entry channel, whether it is the lead cable or the emitter, providing the operator with feedback on the progress of the process. When the process reaches the last cutting operation, the sensor signals the controls which set the system for the last cut, as this requires a different operating mode of the apparatus 10. When the last piece is pulled, no cutting is required. The piece is dropped into the vacuum.
The system is capable of removing and flasking vertical and horizontal SIR flux detector elements. The housing 12 is designed to mount, directly or via the associated equipment, onto either a vertical or a horizontal flux detector assembly port. The portability characteristic of this housing 12 also provides ease of field installation and relocation if multiple-site flux detector removals are required in the area.
The system can easily remove, cut and flask multiple flux detector elements at one flux detector assembly port, without repositioning the robotics housing. The system's redundancy in the cutting mechanism maximizes the reliability of cutting operations for a multiple flux detector removal campaign.
Waste containers 70 are capable of storing the active portions of up to six detector elements before disposal.
The system's associated equipment is designed to facilitate the interfacing of station equipment and to provide ease of flux detector element transfers from the reactor core into the waste containers 70. In order to minimize cost, the design of the system uses off-the-shelf components as well existing equipment.
Although the present invention has been described with reference to illustrative embodiments, it is to be understood that the invention is not limited to these precise embodiments, and that various changes and modifications may be effected therein by one skilled in the art. All such changes and modifications are intention to be encompassed in the appended claims.
Referring now to FIG. 2, a typical vertical flux detector unit will be described.
A vertical flux detector unit 216 is installed below deck shield tread plate 220.
The detector 216 comprises a detector assembly 222 and a thimble assembly 224 having thimble bellows 225. The detector assembly 222 includes detector lead cable 226, LemoTM connector 228, and a helium cover gas supply 230. The detector assembly 222 is located below the shield plate 232 and is partially housed in a shielding sleeve 234 embedded in deck concrete 236. A thimble is indicated by reference 238. A detector well cluster is indicated by reference 240.
Referring now to FIG. 3, a typical horizontal flux detector unit will be described. A horizontal flux detector unit 214 comprises a detector assembly 222 and thimble assembly 224. A protective cover 242 surrounds the assemblies 222 and 224. A guide tube assembly is indicated by reference 244. The detector unit is received in the reactor 200 by a shield tank nozzle 246 in the shield tank wall 248.
One known detector arrangement used in CANDIJTM type reactors, for example, has twenty-three vertical and fourteen horizontal SIR flux detector assemblies installed in a single reactor unit. Each assembly provides twelve well tubes in which the detector elements are inserted. The assemblies may contain up to nine operating flux detector elements, one per well tube, that can be removed and replaced in situ individually. To facilitate this operation, the individual detector well tubes and LemoTM connectors are readily accessible and clearly identifiable, with the assembly housing cover removed.
Each flux detector element comprises a lead wire and a lead cable having an emitter core. Vertical and horizontal detector elements are installed into the detector wells such that the emitter portion of the detectors are positioned at the required locations in the reactor core. The emitter portion of the detectors are 0.118 inches (3 mm) in diameter and 33.75 inches long and are attached to a lead cable which is 0.04 inches (1 mm) in diameter and varies in length from 275 to 432 inches depending on the location. The lead wire is typically 12 to 14 inches in length. The vertical detector elements are lnconelTM sheathed co-axial emitter and lead assemblies. Horizontal detector elements are platinum clad co-axial emitter and lnconelTM lead assemblies. Referring now to FIGS. 4A to 4C, a typical SIR flux detector element will be described. A detector element comprises a lead wire 250, lead cable 252 and emitter core 254. A sheath 255 surrounds the detector.
The emitter portion of the detector has a magnesium oxide core 256. In horizontal detectors, the detector element also has an emitter cladding 258.
The lead wire 252 typically has a LemoTM connector 228 and crimp stops 260.
Detector signai deterioration due to the accumulated effects of irradiation affects neutron SIR flux detector elements. This deterioration process during the life of the reactors will lead to SIR flux detector element failures. Other causes of detector failures are manufacturing deficiencies and loss of the flux detector protective environment.
Most reactivity mechanism maintenance programs require failed detector elements to be removed from the reactor. Removal of failed flux detectors requires dedicated flasking equipment because detector elements become radioactive as a result of exposure within the reactor. Also, irradiation of the flux detectors causes radiation hardening of the detector elements. Attempts to remove detectors by winding the irradiated lead cable onto a spool results in a high frequency of cable breaking. Thus, a system for removing irradiated cable in one straight piece using shielded in-station main reactivity mechanism flasks rather than coiling was developed. This system requires the installation of a temporary containment barrier, extensive work and time in a radiation area, and the use of a large and heavy in-station reactivity mechanism flask. A typical in-station reactivity mechanism flask is a shielded flask approximately 33 feet long and 55,000 lb in weight. In addition, in some CANDUTM type reactors, the size of the flask prevents the _4_ used of this system of horizontal and vertical SIR flux detectors in all locations.
It is desirable to have a system for removing and flasking horizontal and vertical SIR fiux detectors that substantially reduces the radiation dose by minimizing the time and work required as well as eliminating the complex procedures and the use of large and heavy equipment. The present inventor has developed a known robotic apparatus to remove the detector from the reactor inch by inch, cutting the detector into 1 inch segments, and transferring these segments to a shielded flask.
This system for individually removing vertical and horizontal SIR flux detectors from reactors consists of: a portable light weight housing that contains robotics and video components, a pneumatic and an electronic control panel, a video monitor, a vacuum unit, flask assembly and associated equipment. The system is portable and is designed to be stored or transported to the flux detector removal sites on a dedicated trolley.
Referring now to FIG. 5, a typical arrangement of the system in transit to a flux detector removal site and the location of its component when coupled to a reactor will be described. The system is stored and transported on trolley indicated generally by reference 302. The trolley has a retractable tow bracket 304, a flask gripper plug 306, a lifting lug 308, a flask assembly 309, a vacuum unit 310, a vacuum hose 312, and a tracking sensor 313. In transit, the trolley stores a pneumatic control panel 314, a electronic control panei 316, and a robotic apparatus 318. In operation, the apparatus 318 is coupled to a reactor 200, typically using a spacing element 320. A pneumatic harness 322 and control cable 324 are connected to the pneumatic control panel 314 and electronic control panel 316. A video monitor 326 provides for monitoring of the removal operation by an operator at a remote location.
The design of the system utilizes a concept whereby the detector lead of an irradiated flux detector element is withdrawn from its position in the well tube by a remotely operated robot. The apparatus in the robotics housing are pneumatically operated to clasp, pull, hold, cut and drop off 1 inch pieces of an irradiated SIR flux detector in a repetitive manner. In a typical cycle, the gripper moves forward from its home position, clasps the flux detector element that is held by a set of spring loaded non release clamps and pulls the element out 1 inch. One of the redundant cutters moves forward from its home position and cuts off the detector element. The gripper transports the piece to an ejection port and releases it to be sucked into the vacuum hose.
The 1 inch piece of detector element is then transported by the vacuum system into a waste container located in a dedicated flask. Tracking of the 1 inch piece during flasking is provided to ensure that the piece of detector was transferred into the shielded flask. A waste container may be transferred using either underwater or dry transfer flasks for waste container temporary or permanent storage. The waste container may be removed from the flask underwater for in-bay storage at an irradiated fuel bay within the reactor facility. Alternatively, the waste container may be transferred to a road transportable flask for transportation to, for example, a permanent in-ground disposal site.
It is desirable to reduce the risk that a cut piece of failed detector element may be dropped or misdirected within the robotic housing during the removal operation, requiring a technician or other personnel to remove the flux detector segment. The removal of a dropped piece of detector results in significant downtime and unnecessarily exposes personnel to the radiation emitted by the detector element.
SUMMARY OF THE INVENTION
The present invention is a flux detector removal apparatus for use in nuclear reactors that reduces the risk that a cut piece of detector will be dropped or misdirected.
In accordance with one aspect of the present invention, there is provided an apparatus for safely removing flux detectors, comprising: a main housing defining a first opening and a second opening; a cutting blade pivotabiy attached to the interior of said main housing, said blade forming a bite around at least a portion of said first opening; a gripper; and pivot means for pivoting said gripper about a second axis perpendicular to said first opening.
In accordance with another aspect of the present invention, there is provided an apparatus for safely removing flux detectors, comprising: a main housing defining a first opening and a second opening; a cutting blade pivotably attached to the interior of said main housing, said blade forming a bite around at least a portion of said first opening; a gripper; and first slide means coupling said gripper to the interior of said main housing for providing movement along a first axis coaxial with said first opening.
In accordance with a further aspect of the present invention, there is provided an apparatus for safely removing flux detectors, comprising: a main housing defining a first opening and a second opening; a cutting blade pivotably attached to the interior of said main housing, said blade forming a bite around at least a portion of said first opening; a gripper; and an element entry housing defining a channel and an interior lateral notch, said element entry housing being at least partially received in said main housing, said channel and said lateral notch being in communication with said first opening.
In accordance with yet another aspect of thepresent invention, there is provided an apparatus for safely removing flux detectors, comprising: a main housing defining a first opening and a second opening; a cutting blade pivotably attached to the interior of said main housing, said blade forming a bite around at least a portion of said first opening; a locking gate including a pair of elongate locking flags having a first end and a second end, and biasing means for rearwardly biased attachment of the first end of each of said flags within said housing; and a gripper attached to the interior of said main housing.
Other aspects and features of the present invention will become apparent to those ordinarily skilled in the art upon review of the following description of specific embodiments of the invention in conjunction with the accompanying figures.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will be further understood from reference to the following drawings in which:
FIG. 1 is a cut-away illustrating typical locations of flux detector units in a CANDUTM type reactor;
FIG. 2 is a cut-away illustrating a typical vertical flux detector unit arrangement;
FIG. 3 is a cut-away illustrating a typical horizontal flux detector unit arrangement;
FIG. 4A is a partial side view cut-away illustrating portions of a typical SIR flux detector element;
FIG. 4B is an end view cut-away illustrating typical SIR flux detector element;
FIG. 4C is a side view cut-away illustrating typical SIR flux detector element, FIG. 5 is a side view illustrating the general arrangement of a typical SIR flux detector removai systems;
FIG. 6 is a right side view of one embodiment of a flux detector removal apparatus according to the present invention;
FIG. 7 is an exploded partial front view of FIG. 6 showing the gripper assembly attached to the tie tube end plate;
' U -F1G. 8 is an exploded partial front view of FIG. 7 with the tie tube end plate removed;
FIG. 9 is an exploded partial front view of FIG. 6 showing the cutting assembly;
FIG. 10A is an exploded partiai top view of FIG. 6 showing the cutting and gripper assemblies;
FIG. 10B is an exploded partial top view of the FIG. 10A showing the locking gate;
FIG. 10C is an exploded perspective view of FIG. 6 showing the gripper in home position;
FIG. 10D is an exploded perspective view of FIG. 6 showing the gripper in forward, downwardly rotated position;
FIG. 11 is a side view of a shielded flask coupled to the flux detector removal apparatus with a nozzle plug received therein;
FIG. 12 is a side view of a shielded flask coupled to the flux detector removal tool with a gripper plug received therein;
FIG. 13A is a side view of a waste container using in the apparatus of FIG. 6;
FIG. 13B is an exploded side view of FIG. 13A showing the basket received in the waste container;
FIG. 13C is a top view of FIG. 13A;
FIG. 14 is a side view of a second embodiment of the shielded flask coupled to the flux detector removal tool with a nozzle plug received therein;
and FIG. 15 is a side view of the apparatus of FIG. 6 configured for vertical SIR flux detector removal and coupled to a reactor.
DETAILED DESCRIPTION OF THE DRAWINGS
Referring now to FIGS. 6 to 10D, a flux detector removal apparatus in accordance with one embodiment of the present invention is indicated generally at 10. The apparatus 10 comprises a housing indicated generally by reference 12, a gripper assembly indicated generally by reference 14, and a cutting assembly indicated generally by reference 16. As will be described in more detail below, the apparatus 10 is used in a flux detector removal system that provides a sealed system for the removal of flux detectors from a CANDUTM type nuclear reactor.
As shown in FIG. 6, the housing 12 comprises a main housing 18, an element entry housing 20, a cover plate 22, withdrawal wells 24, a vacuum tube adapter 25, and a transparent cover 26. In the shown configuration, the apparatus 10 is configured for horizontal SIR flux detector removal. If vertical SIR flux detector removal is desired, the cover plate 22 is removed from the shown position. The cover plate 22 is attached to the main housing 18 using suitable fasteners that provide for easy removal. The adapter 25 is then removed from the shown position. The adapter 25 is also attached to the main housing 18 using suitable fasteners that provide for easy removal. The vacuum tube adapter 25 is then installed in the position formerly occupied by the cover plate 22. The cover plate 22 is then installed in the position formerly occupied by the adapter 25. The switching of the cover plate 22 and the vacuum tube adapter 25 allows for easy re-configuration of the apparatus 10 between horizontal and vertical removal configurations. The operation of the apparatus 10 will now be described in more detail with respect to the shown horizontal removal configuration. For the vertical removal configuration, this description should be read with appropriate changes to directional and positional references according to the vertical removal configuration described above.
As shown in FIG.6, the main housing 18 has an opening in its rear wall which is in communication with a channel in the element entry housing 20.
Flux detectors which are to be removed from the reactor enter the main housing 18 via the element entry channel and rear opening. 0-rings are provided where the main housing 18 contacts the element entry housing 20, the cover plate 22, and the adapter 25 to provide a seal. The transparent cover 26 is attached to the main housing 18 using suitable fasteners that allow the cover 26 to be removed if access to the internal components of the apparatus 10 is desired, for example, to repair or replace components. Tie tubes 28 are mounted to the main housing 18 at one end and are secured at the opposite end by a tie tube end plate 30 (see FIG. 7 for a front plan view of the tie end plate 30). As shown in FIG. 6, tie tubes 28 provide a support structure within the housing 12 on which components of the gripper assembly 14 and cutting assembly 16 can be mounted. In most applications, shielding of the apparatus 10 is required to prevent or minimize the exposure of personnel to the radiation emitted from detector elements received within the housing 12.
As shown in FIG.9, camera housing 87 is attached to the main housing 18 to provide monitoring capabilities. A camera 88 and a light 90, for example, a 6V 10W Quartz light from Phillips, allow the removal operation to be remotely monitored by a technician. A paper gasket is provided between the camera housing 87 and the main housing 18 to create a seal. 0-rings or other sealant means are provided around the camera 88 and light 90 to seal the camera housing 87.
As shown in FIG. 8, the gripper assembly 14 comprises a gripper 32, a transition adapter 34 (not shown), a gripper slide assembly 36, an actuator slide assembly 38, and a rotary actuator 40. As shown in FIG. 10C, the gripper 32 is preferably a parallel jaw gripper, for example, a 190 Series gripper from PHD, Inc.. The gripper 32 has a jaw, indicated generally by reference 112 (see FIG. 1 0B for enlarged view), comprising a pair of elongate jaw members 114 (see FIG. 10B for enlarged view) attached to the gripper 32 on the end nearest the cutting assembly 16. As shown in FIG. 10C, the jaw 112 and jaw members 114 are coaxial with the element entry channel 55 so that the gripper 32 can easily grasp a detector element received within the housing 12. The jaw members 114 are each capable of lateral movement providing for the gripper 32 to grasp a detector element. Typically both jaw members 114 have coordinated movement, moving either towards the bite to grasp a detector element or away from the bite to release a detector element.
If desired, the jaw members 114 may be operated differently. For example, one jaw member 114 may be stationary while the second jaw member 114 moves between a locked (grasping) and unlocked (releasing) position.
Parallel jaw grippers are preferable because of their compact size, making it easier to handle small parts in the confined working area of the housing 12.
Other types of grippers may be used. If desired, the gripper jaw may be customized to more easily grip the flux detector elements. As shown in FIG.
10C, The gripper 32 is operably connected to the gripper slide assembly 36 by the transition adapter 34. The gripper slide assembly 36 provides the gripper 32 with independent longitudinal movement within the housing 12.
The gripper slide assembly 36 is preferably a cantilever type slide, for example, a Series SB slide from PHD, Inc.. As shown in FIG.8, mounting plate 41, gripper slide bracket 42 and suitable fasteners couple the slide assembly 36 to the rotary actuator 40.
As shown in FIG. 8, the rotary actuator 40 may be a single vane or double vane unit, for example, the actuator may be a PV Series rotary actuator from Schrader Bellows. The rotator actuator 40 includes a roll pin 45 that provides pivotal or rotary movement to the gripper 32. As shown in FIG. 6, a mounting plate 44, mounting brackets 48 attached on the lower tie tubes 28, and suitable fasteners couple the rotator actuator 40 to the actuator slide assembly 38. The actuator slide assembly 38 is preferably a saddle slide, for example, an M Series saddle slide by PHD, Inc.. The actuator slide assembly 38 provides the gripper assembly 14 with longitudinal movement within the housing 12.
As shown in FIGS. 9 and 10A, the cutting assembly 16 comprises a pair of redundant cutters including an upper moving blade 50 (see FIG. 10C
for enlarged view), a lower stationary blade 52 (see FIG. 10C for enlarged view), a cutter slide assembly 54, and a cylinder 58. During normal operation, only one of the two cutters is used. Redundant cutters are provided so that a secondary or backup cutter is available should the first cutter break down during a removal operation. As shown in FIG. 10C, the cutting assembly 16 also comprises a locking gate 56 received within the element entry channel 55 of the element entry housing 20. As shown in FIG.
10B, the locking gate 56 comprises a pair of locking flags 60, a pair of dowel pins 61, and a pair of torsion springs 62). The dowel pins 61 attach the locking flags 60 to the element entry channel and couple the flags 60 to the torsion springs 62. The torsion springs 62 apply a rearwardly biasing force against the locking flags 60 so that the flags 60 are normally in a closed position.
As shown in FIG. 10A, the cutter slide assembly 54 is attached to the rear wall of the main housing 18 using suitable fasteners. Preferably, a paper gasket is located between the slide assembly 54 and the rear wall of the main housing 18. The cutter slide assembly 54 is preferably a cantilever type slide, for example, a Series SB slide from PHD, Inc.. The slide assemblies 54 provide for lateral movement of the redundant cutters within the housing 12.
In their home position, the cutters are removed from working area where a detector would normally be present during operation. When the cutters are in their forward position, the bite created by the cutting blades 50 and 52 would surround a detector from one side.
As shown in FIG. 10A, the lower stationary blade 52 is attached to slide assembly 54 by means of suitable fasteners. Upper moving blade 50 is pivotably mounted to lower blade 52 in offsetting relation using a suitable fastener near the bite. Cylinder 58 couples upper blade 50 to lower blade 52 at the opposite end nearest the transparent cover 26. The pivotable connection of the upper blade 50 to the lower blade 52 provides for the upper blade to rotate about a point 63. The cylinder 58 is preferably a pneumatic cylinder, for example, a CDR-24-1 Model cylinder by Clippard Instrument Laboratory, Inc. Upward movement of the cylinder 58 causes the downward rotation of the upper moving blade 50, resulting in the closure of the cutter's bite. If a detector element is held in locked position within the locking gate 56, the closure of the bite will severe the detector element.
As shown in FIG. 10B, the locking gate 56 is used to hold the flux detector to be cut in locked position. As discussed previously, torsion springs 62 apply a rearwardly biasing force against the locking flags 60 so that the flags 60 desire to be in closed position. As shown in FIG. 10C, the element entry housing 20 defines an element entry channel 55 and an interior lateral notch 57 with the element entry channel 55 and the lateral notch 57 being in communication with the opening (not shown) of the element entry housing 20.
In closed position, the mating surfaces of the locking flags 60 meet and the element entry channel 55 is closed. When a flux detector element is within the element entry channel 55, the rearwardly biasing force of the torsion springs 62 holds or locks the detector element so that it cannot be easily moved. This locked position is advantageous for the cutting of the flux detector element.
Referring now to FIGS. 11 and 12, the flux detector removal system in which the apparatus 10 is used will be described. A first vacuum hose (not shown) couples the vacuum outlet adapter 25 (not shown) of the apparatus 10 (not shown) to a shielded flask 64 wherein the cut pieces of detector element are temporarily stored. The shielded flask 64 is lined with lead to prevent or minimize the exposure of personnel to the radiation emitted from the detector element. The flask 64 is relatively small and is designed to be easily handled in the reactor vault for horizontal flux detectors removal or over the reactor deck for vertical removals. Inner wall 66 of the flask 64 defines a holding cavity. An outlet pipe 68 having outlet adapter 74 is located at the bottom of the holding cavity. A support bracket 72 is attached to inner wall 66. Waste container 70 is received within the shielded flask 64 and is supported by the bracket 72. Waste container 70 provides temporary storage of cut flux detector elements.
During the cutting operation, vacuum nozzle plug 76 having a downwardly projecting inlet pipe 78 having inlet adapter 73 is also received within the flask 64. Upper surface 75 of flask 64 meets lower surface 77 of the vacuum nozzle plug 76 flushly, providing a seal. The first vacuum hose couples adapter 25 (not shown) to inlet adapter 73. A second vacuum hose (not shown) couples outlet adapter 74 to a vacuum unit (not shown) to provide suction to the system. This vacuum system provides a sealed environment for the removal and flasking operations. The sealed environment is important in protecting personnel from the radiation hazards created by the removal and disposal of irradiated flux detectors.
Referring now to FIGS. 13A to 13C, the waste container will be described in more detail. The waste container 70 comprises a perforated base 79, an inner basket 81, a coupling 80 and a self-closing lid 82. The lid 82 comprises a pair of mating panels 84. Each panel has an upwardly biasing spring 86, a shaft 92, cotter pins 94 and a bushing 96. Each spring 86 is received in channel defined in the side of the coupling 80. Shaft 92 and pins 94 secure the spring 86 in the channel. Bushing 96 protects the portion of shaft 92 received in the channel. When the vacuum nozzle plug 76(not shown) is not received within the flask 64, the upward bias of the springs 86 maintains the panels 84 in closed position. As shown in FIG. 11, when the vacuum nozzle plug 76 is received within the flask 64, the inlet pipe 78 exerts a downward force on the panels 84 counteracting the upward bias of the springs 86 and opening the panels 84 to receive the inlet pipe 78. The upward bias of the springs 86 causes the panels to close around pipe 78.
When the nozzle plug 76 is removed, the springs 86 quickly re-close the panels 84, sealing the waste container 70.
As shown in FIG. 12, during removal, a gripper plug 100 is received within the flask 64. The gripper plug 100 has latches which releasably engage the coupling 80 allowing the waste container to be remotely lifted and transported to a desired location for disposal, storage, or transportation to an off-site storage location.
Referring now to FIG. 14, another embodiment of the shielded flask and nozzle plug will be described. In the shown embodiment, an outlet pipe 69 is located in the nozzle plug 76 rather than the shielded flask 64. When the plug 76 is received in the flask 64, the outlet pipe 69 opens into the holding cavity and is located near the inner wall 66 to accommodate inlet nozzle 78. The inlet nozzle 78 has a lower vertical region and upper inclined region. The lower vertical region enters the waste container 70 as previously described. Instead of a support bracket, the waste container 70 rests on the bottom of the holding cavity.
Referring now to FIG. 15, the vertical removal configuration will be briefly described. In the vertical removal configuration, the cover plate 22 (not shown) and the vacuum tube adapter 25 (not shown) are switched as described above. In the shown embodiment, the apparatus 10 is contained within a shielding 98 which prevents or minimizes the exposure of personnel to radiation emitted from detector elements received within the housing 12 (not shown). The shielding 98 is preferably lead lined. A first vacuum hose 102 connects the apparatus 10 to the shielded flash 64. Pneumatic cables 104 and control cables 106 provide a communication pathway between the air supply and apparatus control system respectively. Differences in the environment surrounding vertical SIR flux detector assembly ports require the use of a shielded pedestal 108 to provide clearance from reactivity mechanism components in the area, for example, shielding blocks. The pedestal 108 couples directly to the element entry housing 20 on one side. A
pedestal adapter 110 couples the opposite end of the pedestal 108 to the reactor.
In operation, the flux detector removal system is moved to the location of a horizontal or vertical SIR flux detector assembly port where it is desired to remove one or more failed flux detector elements. The protective cap covering the assembly port is removed by a remotely operated robot thereby exposing the flux detector(s) of interest. The detector lead of the element to be removed is then withdrawn from its position in the well tube. The apparatus 10 is then coupled to the assembly port of the reactor at the element entry housing 20. The apparatus 10 may be connected directly or using a spacing element between the element entry housing 20 and the reactor. When the apparatus 10 is connected to the reactor, the detector lead wire passes through the entry channel of the element entry housing 20 and forces open the normally closed locking flags 60 of the locking gate 56. The lead wire of the detector is now within the main housing 18. The torsion springs 62 impart a rearwardly biasing force on the locking flags 60 causing them to close on the detector lead wire, holding it in a locked position.
The gripper 32 then moves forward from its home position and grasps the detector. The gripper 32 then moves backwards to its home position, thereby pulling the detector further within the main housing 18. The gripper 32 preferably pulls the detector within the housing 18 such that a 1 inch piece of detector may be cut, although a longer or shorter piece of detector may be cut off. One of the redundant cutters will now cut the 1 inch piece of detector as will be described below. Either cutter may be used. The operator typically selects a single cutter to be used for the duration of a detector removal campaign, although the operator may switch between cutters if desired.
In normal position, the upper moving blade 50 is in its upper position with respect to the lower stationary blade 52, forming a bite. If the upper blade 50 is not in its normal upper position, it is moved to its upper position.
One of the redundant cutters then moves forward from its home position towards the detector now received within the element entry channel such that the detector is within the bite formed by the upper blade 50 and lower blade 52. The upper blade 50 is then moved to its lower position, closing the bite and severing a 1 inch piece of detector. The upper blade 50 is then moved to its normal upper position, and the cutter is moved back to its home position.
The gripper 32 now holds the 1 inch cut piece of detector which now requires disposal in the withdrawal well 24 of the main housing 18. The gripper 32 is then rotated or pivoted downwards so that the 1 inch cut piece within the gripper jaw is at a modest height above the withdrawal well 24 (see FIG. 10D). The gripper 32 then releases the 1 inch cut piece into the well 24, which is then transported via the first vacuum hose to the water container 70 in the shielded flask 64 by the suction provided by the vacuum unit. The cut piece is monitored within the main housing 18 by the video camera 88 assisted by the light 90. The cut piece is also tracked by a second video camera (not shown) during flasking to ensure that it is transferred into the shielded flask 64. The second camera is located at the flasking station by the canister entrance. The system operates in a repetitive manner, gripping, cutting, and disposing of 1 inch cut pieces until the entire detector element to be removed has been cut and transferred to the waste container 70.
The waste container 70 may be transferred from the flask 64 using either underwater or dry transfer flasks for waste container temporary or permanent storage. The waste container 70 may be removed from the flask underwater for in-bay storage at an irradiated fuel bay within the reactor facility. Alternatively, the waste container 70 may be transferred to a road transportable flask for transportation to, for example, a permanent in-ground disposal site.
During the operation of the system, the actions in the housing 12 are observed via a closed circuit television. The operator is located at a remote location 50 feet away from the flux detector removal site and controls the apparatus 10 with a series of push buttons switches or preferably a touch screen. A touch screen may provide graphical representation of each step of the process. The touch screen may also list available options in any situation as the apparatus 10 progresses through its cycle. Thus, in the event of a stoppage the touch screen could be made to show what options are available to the operator, assisting in the decision making process.
The system can be made run on a single mode or in a repeat (automatic) mode and will stop if any action is not completed. The speed of the removal operation is adjustable. Emergency stop and override functions are provided in case of abnormal operation. The programmer and the control components are situated at the operator remote location. In case of need, power valves can be manually actuated to operate the apparatus 10 remotely.
The system requires air pressure (100 psi) and 120 volt at 60 Hz, to function normally, however, as all electrical components operate on 24 volts DC, a back up battery pack could be used to maximize reliability.
The system's programmable logic controller (PLC), is a stepping controller which will not allow the operation of the system to continue without specific conditions being met each step of the flux detector removal and flasking process. Each component of the apparatus 10 has a sensor at its end of travel, which changes stated when the action is completed. The PLC
reviews the status of the system and will only proceed to the next step of the process if all conditions are met. If abnormal conditions are found, the system stops its operation and waits for operator input.
An important feature of the system is the capability of recognizing the presence of the flux detector element in the detector entry channel of the robotics housing. A sensor signals which portion of detector element is in the entry channel, whether it is the lead cable or the emitter, providing the operator with feedback on the progress of the process. When the process reaches the last cutting operation, the sensor signals the controls which set the system for the last cut, as this requires a different operating mode of the apparatus 10. When the last piece is pulled, no cutting is required. The piece is dropped into the vacuum.
The system is capable of removing and flasking vertical and horizontal SIR flux detector elements. The housing 12 is designed to mount, directly or via the associated equipment, onto either a vertical or a horizontal flux detector assembly port. The portability characteristic of this housing 12 also provides ease of field installation and relocation if multiple-site flux detector removals are required in the area.
The system can easily remove, cut and flask multiple flux detector elements at one flux detector assembly port, without repositioning the robotics housing. The system's redundancy in the cutting mechanism maximizes the reliability of cutting operations for a multiple flux detector removal campaign.
Waste containers 70 are capable of storing the active portions of up to six detector elements before disposal.
The system's associated equipment is designed to facilitate the interfacing of station equipment and to provide ease of flux detector element transfers from the reactor core into the waste containers 70. In order to minimize cost, the design of the system uses off-the-shelf components as well existing equipment.
Although the present invention has been described with reference to illustrative embodiments, it is to be understood that the invention is not limited to these precise embodiments, and that various changes and modifications may be effected therein by one skilled in the art. All such changes and modifications are intention to be encompassed in the appended claims.
Claims (31)
1. An apparatus for safely removing flux detectors, comprising:
a main housing defining a first opening and a second opening;
a cutting blade attached to the interior of said main housing; an element attached to or forming a part of said main housing and facing said blade; said blade and element forming a bite around at least a portion of said first opening;
a gripper; and pivot means for pivoting said gripper about a second axis perpendicular to said first opening.
a main housing defining a first opening and a second opening;
a cutting blade attached to the interior of said main housing; an element attached to or forming a part of said main housing and facing said blade; said blade and element forming a bite around at least a portion of said first opening;
a gripper; and pivot means for pivoting said gripper about a second axis perpendicular to said first opening.
2. The apparatus of claim 1, wherein the element is a second cutting blade.
3. An apparatus for safely removing flux detectors, comprising:
a main housing defining a first opening and a second opening;
a cutting blade attached to the interior of said main housing; an element attached to or forming a part of said main housing and facing said blade; said blade and element forming a bite around at least a portion of said first opening;
a gripper; and first slide means coupling said gripper to the interior of said main housing for providing movement along a first axis coaxial with said first opening.
a main housing defining a first opening and a second opening;
a cutting blade attached to the interior of said main housing; an element attached to or forming a part of said main housing and facing said blade; said blade and element forming a bite around at least a portion of said first opening;
a gripper; and first slide means coupling said gripper to the interior of said main housing for providing movement along a first axis coaxial with said first opening.
4. The apparatus according to claim 3, wherein the cutting blade is attached to the interior of said main housing.
5. The apparatus as claimed in claim 4, further comprising pivot means for pivoting said gripper about a second axis perpendicular to said first axis.
6. The apparatus as claimed in claim 5, further comprising an element entry housing defining a channel and an interior lateral notch, said element entry housing being at least partially received in said main housing, said channel and said lateral notch being in communication with said first opening.
7. The apparatus as claimed in claim 6, wherein said channel and said notch are coaxial with said first opening.
8. The apparatus as claimed in claim 6 or 7, wherein the length of said element entry housing is less than the length of the exposed portion of a standard SIR
flux detector.
flux detector.
9. The apparatus of any of claims 1-9, wherein the element is a second cutting blade.
10. An apparatus for safely removing flux detectors, comprising:
a main housing defining a first opening and a second opening;
a cutting blade attached to the interior of said main housing; an element attached to or forming a part of said main housing and facing said blade; said blade and element forming a bite around at least a portion of said first opening;
a gripper; and an element entry housing defining a channel and an interior lateral notch, said element entry housing being at least partially received in said main housing, said channel and said lateral notch being in communication with said first opening.
a main housing defining a first opening and a second opening;
a cutting blade attached to the interior of said main housing; an element attached to or forming a part of said main housing and facing said blade; said blade and element forming a bite around at least a portion of said first opening;
a gripper; and an element entry housing defining a channel and an interior lateral notch, said element entry housing being at least partially received in said main housing, said channel and said lateral notch being in communication with said first opening.
11. The apparatus according to claim 10, wherein the cutting blade is attached to the interior of said main housing.
12. The apparatus as claimed in claim 10 or 11, wherein said channel and said notch are coaxial with said first opening.
13. The apparatus as claimed in any one of claims 10 to 12, wherein the length of said element entry housing is less than the length of the exposed portion of a standard SIR flux detector.
14. An apparatus for safely removing flux detectors, comprising:
a main housing defining a first opening and a second opening;
a cutting blade attached to the interior of said main housing; an element attached to or forming part of said main housing and facing said blade; said blade and element forming a bite around at least a portion of said first opening;
a locking gate including a pair of elongate locking flags having a first end and a second end, and biasing means for rearwardly biased attachment of the first end of each of said flags within said housing; and a gripper attached to the interior of said main housing.
a main housing defining a first opening and a second opening;
a cutting blade attached to the interior of said main housing; an element attached to or forming part of said main housing and facing said blade; said blade and element forming a bite around at least a portion of said first opening;
a locking gate including a pair of elongate locking flags having a first end and a second end, and biasing means for rearwardly biased attachment of the first end of each of said flags within said housing; and a gripper attached to the interior of said main housing.
15. The apparatus according to claim 14, wherein the cutting blade is pivotably attached to the interior of said main housing.
16. The apparatus as claimed in claim 14 or 15, further comprising an element entry housing defining a channel and a lateral notch, said element entry housing being at least partially received in said main housing, said channel and said lateral notch being in communication with said first opening, wherein said biasing means provides for rearwardly biased attachment of the first end of each of said flags within said notch.
17. The apparatus as claimed in any one of claims 14 to 16, wherein said channel and said notch are coaxial with said first opening.
18. The apparatus as claimed in claim 17, wherein said biasing means is a spring.
19. The apparatus as claimed in claim 18, wherein the second end of said flags meet at the midpoint point of said notch.
20. The apparatus as claimed in claim 18, wherein the length of said flags is less than half the width of said notch.
21. The apparatus as claimed in any one of claims 7 to 13, further comprising a locking gate including a pair of elongate locking flags having a first end and a second end, and biasing means for rearwardly biased attachment of the first end of each of said flags within said notch.
22. The apparatus as claimed in claim 21, wherein said channel and said notch are coaxial with said first opening.
23. The apparatus as claimed in claim 22, wherein said biasing means is a spring.
24. The apparatus as claimed in claim 23, wherein the second end of said flags meet at the midpoint point of said notch.
25. The apparatus as claimed in claim 23, wherein the length of said flags is less than half the width of said notch.
26. The apparatus as claimed in any one of claims 2 to 25, further comprising lateral slide means coupled to said cutting blade for providing movement of the cutting blade along an axis parallel to said second axis.
27. The apparatus as claimed in any one of claims 2 to 25, further comprising second slide means coupling said gripper and said first slide means to the interior of said main housing for providing extended movement of the gripper along an axis parallel to said first axis.
28. The apparatus as claimed in any one of claims 1 to 27, wherein said gripper is a parallel jaw gripper.
29. The apparatus as claimed in any one of claims 2, 6 to 27, wherein said gripper has a jaw comprising a pair of elongate jaw members, said jaw members attached to the end of said gripper nearest said cutting blade, said jaw members being parallel to the axis of said first opening, each of said jaw members being capable of lateral movement along an axis parallel to said second axis.
30. The apparatus as claimed in any one of claims 1 to 29, further comprising a vacuum for removing cut portions of a flux detector from said main housing.
31. The apparatus as claimed in any one of claims 10-30, wherein the element is a second cutting blade.
Priority Applications (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002594537A CA2594537A1 (en) | 2003-06-12 | 2003-06-12 | Flux detector removal apparatus |
| CA2595106A CA2595106C (en) | 2003-06-12 | 2003-06-12 | Flux detector removal apparatus |
| CA002432268A CA2432268C (en) | 2003-06-12 | 2003-06-12 | Flux detector removal apparatus |
| CA002594966A CA2594966A1 (en) | 2003-06-12 | 2003-06-12 | Flux detector removal apparatus |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002432268A CA2432268C (en) | 2003-06-12 | 2003-06-12 | Flux detector removal apparatus |
Related Child Applications (3)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002594966A Division CA2594966A1 (en) | 2003-06-12 | 2003-06-12 | Flux detector removal apparatus |
| CA002594537A Division CA2594537A1 (en) | 2003-06-12 | 2003-06-12 | Flux detector removal apparatus |
| CA2595106A Division CA2595106C (en) | 2003-06-12 | 2003-06-12 | Flux detector removal apparatus |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2432268A1 CA2432268A1 (en) | 2004-12-12 |
| CA2432268C true CA2432268C (en) | 2008-09-09 |
Family
ID=33557626
Family Applications (4)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002594537A Abandoned CA2594537A1 (en) | 2003-06-12 | 2003-06-12 | Flux detector removal apparatus |
| CA002432268A Expired - Lifetime CA2432268C (en) | 2003-06-12 | 2003-06-12 | Flux detector removal apparatus |
| CA002594966A Abandoned CA2594966A1 (en) | 2003-06-12 | 2003-06-12 | Flux detector removal apparatus |
| CA2595106A Expired - Lifetime CA2595106C (en) | 2003-06-12 | 2003-06-12 | Flux detector removal apparatus |
Family Applications Before (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002594537A Abandoned CA2594537A1 (en) | 2003-06-12 | 2003-06-12 | Flux detector removal apparatus |
Family Applications After (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002594966A Abandoned CA2594966A1 (en) | 2003-06-12 | 2003-06-12 | Flux detector removal apparatus |
| CA2595106A Expired - Lifetime CA2595106C (en) | 2003-06-12 | 2003-06-12 | Flux detector removal apparatus |
Country Status (1)
| Country | Link |
|---|---|
| CA (4) | CA2594537A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| RU2713504C2 (en) * | 2015-10-09 | 2020-02-05 | Шкода Йс А.С. | Neutron flux sensor and/or thermocouple elimination device |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2017059833A1 (en) * | 2015-10-09 | 2017-04-13 | Skoda Js A.S. | Device for disposal of neutron flux sensors and/or thermocouples |
-
2003
- 2003-06-12 CA CA002594537A patent/CA2594537A1/en not_active Abandoned
- 2003-06-12 CA CA002432268A patent/CA2432268C/en not_active Expired - Lifetime
- 2003-06-12 CA CA002594966A patent/CA2594966A1/en not_active Abandoned
- 2003-06-12 CA CA2595106A patent/CA2595106C/en not_active Expired - Lifetime
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| RU2713504C2 (en) * | 2015-10-09 | 2020-02-05 | Шкода Йс А.С. | Neutron flux sensor and/or thermocouple elimination device |
Also Published As
| Publication number | Publication date |
|---|---|
| CA2594537A1 (en) | 2004-12-12 |
| CA2595106A1 (en) | 2004-12-12 |
| CA2595106C (en) | 2010-05-11 |
| CA2432268A1 (en) | 2004-12-12 |
| CA2594966A1 (en) | 2004-12-12 |
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| EEER | Examination request | ||
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