KR20210082167A - Control rod drive mechanism with heat pipe cooling - Google Patents

Abstract

A cooling system for a reactor control rod drive mechanism (CRDM) includes an evaporation section located inside or adjacent to the CRDM and a condensing section fluidly coupled to the evaporation section. The cooling system may include a series of hot fins extending upward from the drive coil of the CRDM and heat pipes extending through the hot fins and drive coil. The fluid is evaporated with the heat generated by the CRDM while in the evaporation section of the heat pipe and travels from the evaporation section to the condensing section of the hot fin. The fluid is cooled and condensed while in the condensing section and recirculated back to the evaporation section. These passive natural circulation cooling systems reduce or eliminate the requirement in air cooling or the number of water hoses, piping and other water pumping equipment commonly used to cool CRDMs, thereby increasing reactor reliability and reactor operation and maintenance. to simplify

Description

Control rod drive mechanism with heat pipe cooling

This application claims priority to U.S. Provisional Patent Application No. 62/736,250, filed September 25, 2018, entitled Control Rod Drive Mechanism with Heat Pipe Cooling, the contents of which are incorporated herein by reference in their entirety. do.

This application is also a continuation-in-part of U.S. Patent Application Serial No. 15/858,727 [Title: Control Rod Drive Mechanism (CRDM) with Remote Disconnection Mechanism], filed December 29, 2017, and Priority is claimed to U.S. Provisional Patent Application No. 62/441,015, which is incorporated herein by reference in its entirety.

This invention was invented with government support under contract number DE-NE0000633 awarded by the Department of Energy. The Government reserves certain rights in this invention.

The present disclosure relates generally to a cooling system for a nuclear reactor control rod drive mechanism.

A control rod drive mechanism (CRDM) at the top of a reactor pressure vessel (RPV) can actuate or disengage the drive shaft by gravity during rapid control rod insertion (SCRAM). The CRDM may be placed in an upper containment vessel (CNV) containing the RPV and may use an electric motor to control the movement of the drive shaft. The electric motor can be driven remotely by electromagnetic force across the pressure vessel boundary.

CRDM electric motors are cooled by a reactor component cooling water system (RCCWS) or forced air cooling. A water cooling system may incorporate a complex array of water hoses that circulate water to remove heat from the electric motor coils. The hose is difficult to remove when the RPV is removed from the CNV for refueling. CRDM failures due to leaks or blockages in cooling system hoses can trigger a containment evacuation system (CES) to shut down the reactor.

Alternative air cooling systems may not be suitable for some reactors. For example, the evacuated CNV creates a vacuum environment around the outside of the RPV to eliminate convective heat transfer to one cooling option.

The included drawings are for illustrative purposes and are intended to provide examples of possible structures and operations for the disclosed inventive systems, apparatus, methods, and computer-readable storage media. These drawings do not limit any changes in form and detail that may be made by those skilled in the art without departing from the spirit and scope of the disclosed implementations.

1 is a conceptual diagram illustrating an example of a nuclear reactor module.
FIG. 2 is a side cross-sectional perspective view showing the upper head of a reactor pressure vessel with control rod drive mechanisms (CRDMs) inside the containment vessel; FIG.
3 is a perspective view illustrating a control rod assembly partially inserted into a nuclear fuel assembly;
4A and 4B are conceptual views illustrating dismantling of the reactor pressure vessel.
5 is a side view of a single-hinge type control rod drive mechanism;
6 is a plan view showing a single-hinge type control rod driving mechanism.
FIG. 7 is a side cross-sectional view of the control rod driving mechanism in FIG. 5 .
8 is a further enlarged detailed side cross-sectional view of a single-hinge latch assembly within a control rod drive mechanism.
9 is a cross-sectional view of the drive assembly;
10 is a cross-sectional plan view of the single-hinge clasp assembly of FIG. 8;
11A-11E are side cross-sectional views showing another operating state of the single-hinge type control rod driving mechanism of FIG. 5;
12 is a side view of a double-hinge type control rod drive mechanism;
13A and 13B are side cross-sectional views showing another operating state of the double-hinge type control rod driving mechanism of FIG. 12 ;
14 is an enlarged side cross-sectional view of the double-hinge clasp assembly within the control rod drive mechanism of FIG. 12;
15 is a cross-sectional view of the double-hinge clasp assembly of FIG. 14;
16A-16G are conceptual diagrams showing different control rod driving mechanisms (FIG. 5 or FIG. 12) operating states;
16A-16B illustrate an exemplary procedure for using a drive mechanism to engage and linearly move a drive shaft.
16C-16G show an exemplary procedure for using a remote disconnection system to disengage a drive shaft from a control rod assembly.
17 is a side cross-sectional perspective view showing the upper head of a reactor pressure vessel within an upper containment vessel using a CRDM cooling system;
18 is an exploded perspective view of a CRDM cooling system;
19 is a cross-sectional view of a lower section of a CRDM cooling system.
20 is a top cross-sectional plan view of a CRDM cooling system.
21 is an enlarged plan cross-sectional view of a top section of a CRDM cooling system;
22 is a three-dimensional side cross-sectional view of a CRDM cooling system.
23 is an enlarged three-dimensional cross-sectional side view of a CRDM cooling system.

A simplified cooling system uses heat pipes to cool the electric motor of the control rod drive mechanism (CRDM) while operating in the emptied containment vessel (CNV). The cooling system does not rely on active water cooling via the Reactor Element Cooling Water System (RCCWS), and is designed with CRDM, CNV It greatly simplifies the RCCWS design.

The cooling system overcomes the cooling limitations for CRDMs operating in vacuum environments that prevent effective convective heat transfer. The heat pipe can transfer heat from the CRDM electrical coil to a finned heat exchanger positioned above the CRDM electrical coil, increasing its ability to transfer heat to the surrounding CNV vessel wall via radiation into the vacuum. The cooling system may include an envelope of the same or larger diameter as the electrical coil and does not require an external power source or external fluid transfer. As an alternative option, the cold end of the heat pipe can be mounted directly to the CNV vessel wall above the CRDM to further enhance conduction heat transfer.

1 shows a cross-sectional view of an exemplary integrated nuclear reactor module 5 including a reactor pressure vessel 52 . The reactor core 6 is shown positioned adjacent the lower head 55 of the reactor pressure vessel 52 . The reactor core 6 may be positioned on a shroud 22 , which surrounds the reactor core 6 around its sides. A riser section 24 is located above the reactor core 6 surrounded by the steam generator 30 .

When the first coolant 28 is heated by the reactor core 6 as a result of a fission event, the first coolant 28 flows from the shroud 22 to a torus located above the reactor core 6 ( Annulus 23 may be directed upwards and exit riser 24 . This may result in additional first coolant 28 being drawn into the shroud 22 and heated again by the reactor core 6 , which draws more first coolant 28 into the shroud 22 . The first coolant 28 coming from the riser 24 may be cooled by the steam generator 30 and directed out of the reactor pressure vessel 32 , then through natural circulation to the bottom of the reactor pressure vessel 52 . return to

A first coolant 28 is circulated past the reactor core 6 to become a hot coolant TH, and then continues to rise upward through the riser section 24, where it is directed downward into the annular steam generator. By cooling by (30), it becomes a low-temperature coolant (TC).

One or more control rod drive mechanisms CRDM 10 are operatively coupled to a plurality of drive shafts 20 that may be configured to interface with a plurality of control rod assemblies 80 positioned above the reactor core 6 .

The reactor pressure vessel baffle plate 45 may be configured to direct the first coolant 28 towards the lower end 55 of the reactor pressure vessel 52 . The surface of the reactor pressure vessel baffle plate 45 may directly contact and deflect the first coolant 28 exiting the riser section 24 . In some examples, the reactor pressure vessel baffle plate 45 may be made of stainless steel or other material.

The lower end 55 of the reactor pressure vessel 52 may include an elliptical, domed, concave or hemispherical portion 55A, wherein the elliptical portion 55A dispenses the first coolant 28 into the reactor core. 6) is directed toward The elliptical portion 55A may enhance the natural circulation of the first coolant through the reactor core 6 and increase the flow rate. Further optimization of the coolant flow 28 may be obtained by changing the radius of curvature of the reactor pressure vessel baffle plate 45 to eliminate/minimize boundary layer separation and stagnation regions.

The reactor pressure vessel baffle plate 45 is shown positioned between the pressurizer region 40 and the top of the riser section 24 . The pressurizer region 40 is shown to include a spray nozzle and one or more heaters configured to control pressure or maintain a steam dome within the head or upper end 56 of the reactor pressure vessel 52 . have. The first coolant 28 located below the reactor pressure vessel baffle plate 45 may comprise a relatively sub-cooled coolant TSUB, while the upper end of the reactor pressure vessel 52 ( The first coolant 28 in the pressurizer region 40 in 56 may comprise a substantially saturated coolant (TSAT).

The fluid level of the first coolant 28 is shown as being above the reactor pressure vessel baffle plate 45 and in the pressurizer region 40 , such that the lower end 55 of the reactor pressure vessel 52 and the reactor pressure are present. The entire volume between the vessel baffle plates 45 may be filled with the first coolant 28 during normal operation of the reactor module 5 .

The shroud 22 may support one or more control rod guide tubes 94 that serve to guide the control rod assembly 80 inserted into or removed from the reactor core 6 . In some examples, the drive shaft 20 may pass through the reactor pressure vessel baffle plate 45 and through the riser section 24 to control the position of the control rod assemblies 80 relative to the reactor core 6 .

The reactor pressure vessel 52 may include a flange by which the lower head 55 may be removably attached to the upper reactor vessel body 60 of the reactor pressure vessel 52 . In some examples, riser section 24, baffle plate 45, and other internal components are disengaged from upper reactor vessel body 60 when lower head 55 is separated from upper reactor vessel body 60, such as during a refueling operation, for example. The reactor core 6 may be retained within the lower head 55 , while it may be held within the vessel body 60 .

Also, the upper reactor vessel body 60 may be accommodated within the containment vessel 70 . Any air or other gas in containment region 74 located between containment vessel 70 and reactor pressure vessel 52 may be removed or evacuated during or prior to startup of the reactor. Gases evacuated or evacuated from containment vessel 74 may include non-condensable gases and/or condensable gases. During emergency operation, steam and/or steam may be vented from the reactor pressure vessel 52 into the containment region 74, or only a negligible amount of a non-condensable gas (eg, hydrogen) may be contained. It may be vented or exhausted to region 74 .

2 shows a top cross-sectional view of a nuclear reactor module 5 and an exemplary control rod drive mechanism (CRDM) assembly 10 . The nuclear reactor module 5 may include an upper containment vessel 76 containing at least a portion of the CRDM 10 . A plurality of drive shaft housings 77 may be located within the upper containment vessel 76 . A plurality of drive shafts 20 associated with the CRDM 10 may be located in a reactor pressure vessel 52 housed within a main containment vessel 70 . The drive shaft housing 77 may be configured to receive at least a portion of the drive shaft 20 during operation of the nuclear reactor module 5 . In some examples, substantially all of the CRDM 10 may be contained within the main containment vessel 70 .

Upper containment vessel 76 may be removably attached to primary containment vessel 70 . By removing the upper containment vessel 76 , the overall size and/or volume of the reactor module 5 may be reduced, which may affect the peak containment pressure and/or water level. In addition to reducing the overall height of the reactor module 5 , removing the upper containment vessel 76 from the main containment vessel 70 can further reduce the weight and shipping height of the reactor module 5 . have. In some exemplary reactor modules, several tons of weight can be removed for each foot, which reduces the overall height of the reactor module 5 .

Reactor pressure vessel 52 and/or main containment vessel 70 may include one or more steel vessels. Also, the main containment vessel 70 may include one or more flanges by which the top or bottom head of the main containment vessel 70 can be removed from the containment vessel body, for example during a refueling operation.

During refueling, the reactor module 5 may be relocated from an operating bay to a refueling bay, and a series of decomposition steps may be performed in the reactor module 5 . The working bay can be connected to the refueling bay by water, so that the reactor module 5 is transported under the water. The main containment vessel 70 may be disassembled such that access to the CRDM 10 and/or the reactor pressure vessel 52 is achieved, eg, the top or bottom head may be separated from the containment vessel body. In this phase of refueling, the reactor pressure vessel 52 may be kept completely submerged in the surrounding water in the refueling bay. In some examples, an upper portion of the CRDM 10 , such as the plurality of drive shaft housings 77 , may be positioned above water to facilitate access to the CRDM 10 in a dry environment. In another example, the entire CRDM 10 may be submerged in a pool of water in the refueling bay.

The CRDM 10 may be mounted to the upper head of the reactor pressure vessel 52 by a nozzle 78 . The nozzle 78 may be configured to support the CRDM 10 when the main containment vessel 70 is partially or completely disassembled during a refueling operation. Further, the CRDM 10 may be configured to control and/or support the position of the drive shaft 20 within the reactor pressure vessel 52 .

The reactor pressure vessel 52 may comprise a substantially capsule-shaped vessel. In some examples, the reactor pressure vessel 52 may have a height of approximately 20 meters. The drive shaft 20 may extend from a CRDM 10 located in the upper head of the reactor pressure vessel 52 to the lower head of the reactor pressure vessel 52 such that they are inserted into the reactor core 6 by a control rod assembly. 80 (Fig. 1). The distance from the upper head of the reactor pressure vessel 52 to the reactor core 6 is less than the overall height of the reactor pressure vessel 52 , but is approximately 20 meters long, or in some examples, the height of the reactor pressure vessel 52 . This may result in a somewhat smaller length of the drive shaft 20 .

3 is a perspective view of a control rod assembly 80 , which is partially inserted into and partially retained over a nuclear fuel assembly 90 in a nuclear reactor core 6 . As described above, multiple drive shafts 20 extend on top of the reactor core 6 down from the rod drive mechanism 10 . The control rod assembly 80 may include a cylindrical hub 82 attached to the bottom end of the drive shaft 20 . Arm 84 extends radially outward from cylindrical hub 82 and is attached to the upper end of control rod 86 at its distal end.

Control rods 86 extend into nuclear fuel assembly 90 , which is replaced by a fuel bundle forming part of reactor core 6 . The nuclear fuel assembly 90 may include an upper nozzle 92 supporting a plurality of guide tubes 94 . A guide tube 94 extends between the fuel rods (not shown) down from the nozzle 92 . The control rod 86 controls the fission rate of uranium and plutonium in the nuclear fuel rod.

The control rod 86 is typically held over the nuclear fuel assembly 90 by a drive shaft 20 or is held somewhat inserted into the nuclear fuel assembly 90 . The reactor core 6 may overheat. Nuclear SCRAM operation is initiated when the CRDM 10 of FIG. 1 releases the drive shaft 20 to drop the control rod 86 into the guide tube 94 between the fuel rods.

4A shows a cross-sectional view of an exemplary reactor pressure vessel 52 . The CRDM 10 may be mounted to an upper head 96 of the reactor pressure vessel 52 and configured to support a plurality of drive shafts 20 , the drive shafts being configured to support the upper reactor vessel of the reactor pressure vessel 52 . It extends through the length of the body 60 towards the reactor core 6 located in the lower head 98 of the reactor pressure vessel 52 . In some examples, lower head 98 may be removably attached to upper reactor vessel body 60 , such as by a plurality of bolts at flange 100 .

In addition to receiving a plurality of nuclear fuel rods, the reactor core 6 may be configured to receive a plurality of control rod assemblies 80 , which are movable between the fuel rods to control the power output of the reactor core 6 . can be inserted. When the reactor core 6 generates power, the lower end 102 of the drive shaft 20 may be connected to the control rod assembly 80 . Further, by moving the drive shaft 20 up or down within the reactor pressure vessel 52 , the CRDM 10 may be configured to control the position of the control rod assembly 80 within the reactor core 6 .

For example, when the control rod assembly 80 is removed from the reactor core 6 , the upper end 104 of the drive shaft 20 is a CRDM pressure housing 77 located above the upper head 96 of the reactor pressure vessel 52 . can be accommodated in In some examples, the CRDM pressure housing 77 may include a single pressure vessel configured to receive the upper end 104 of the drive shaft 20 . In another example, the CRDM pressure housing 77 may include a separate housing for each of the drive shafts 20 .

The lower end 102 of the drive shaft 20 is shown disconnected from the control rod assembly 80 , which may be associated with a refueling operation of the reactor core 6 . During the initial phase of the refueling operation, the lower head 98 may remain attached to the upper reactor vessel body 60 while the drive shaft 20 is disconnected from the control rod assembly 80 . The reactor pressure vessel 52 may be kept completely sealed to the surrounding environment, which in some instances includes a pool of water that at least partially surrounds the reactor pressure vessel 52 during the initial phase of a refueling operation. can do.

The CRDM 10 may include remote disconnect mechanisms, whereby the drive shaft 20 does not open or otherwise disassemble the reactor pressure vessel 52 and the control rod assembly 80 . can be disconnected from In some examples, the reactor pressure vessel 52 may form a sealed region 106 , which seals the reactor core 6 , the control rod assembly 80 , and the lower end 102 of the drive shaft 20 . surround By remotely disconnecting the drive shaft 20 , the control rod assembly 80 can be retained within the reactor core 6 when the drive shaft 20 is at least partially returned to the CRDM pressure housing 77 .

4B shows the exemplary reactor pressure vessel 52 of FIG. 4A partially disassembled. During a refueling operation, the lower head 98 may be disengaged from the upper reactor pressure body 60 of the reactor pressure vessel 52 . In some examples, the lower head 98 may be held stationary at the refueling station, while the upper reactor vessel body 60 is lifted by a crane and moved away from the lower head 98 to move the reactor core ( 6) to facilitate access.

The drive shaft 20 is shown in a retracted or withdrawn position so that the lower end 102 can be retained entirely within the upper reactor vessel body 60 and/or the CRDM pressure housing 77 . have. For example, the CRDM 10 raises the lower end 102 of the drive shaft 20 above the lower flange 108 used to mount the upper reactor vessel 60 together with the upper flange 110 of the lower head 98 . can be configured to do so. Retrieving the lower end 102 of the drive shaft 20 into the upper reactor vessel body 60 may provide additional clearance between the lower flange 108 and the upper flange 110 during a refueling operation, and also During transport and/or storage of the upper reactor vessel body 60 , the drive shaft 20 may be prevented from contacting with external objects or from being damaged. Further, when the drive shaft 20 is in the retracted or retracted position, the upper end 104 of the drive shaft 20 may similarly be protected and/or contained by a CRDM pressure housing 77 .

As described above, the control rod assembly 80 may remain fully inserted and held within the reactor core 6 during some or all of the refueling operation. In some instances, maintaining insertion of the control rod assembly 80 within the reactor core 6 may be governed by nuclear regulatory and/or safety considerations.

Single-Hinge Type Control Rod Drive Mechanism

FIG. 5 is a side view and FIG. 6 is a plan view of a single-hinge type control rod drive mechanism 88 including a remote disconnect mechanism. 5 and 6 , the drive shaft housing 77 extends around the clasp mechanism 138 over the upper end of the drive shaft 20 . The drive shaft housing 77 is referred to as an upper pressure boundary.

As described above, the drive shaft 20 enters the reactor pressure vessel RPV 52 of FIG. 2 through a nozzle 78 connected at the top to the bottom end of the drive shaft housing 77 . The bottom end of the drive shaft 20 is removably connected to the control rod assembly 80 as shown in more detail below.

The control rod drive mechanism 88 includes a drive assembly 122 that raises and lowers the drive shaft 20 and the attached control rod assembly 80 . The control rod drive mechanism 88 also includes a disconnect assembly 120 that disconnects the drive shaft 20 from the control rod assembly 80 . Both drive assembly 122 and disconnect assembly 120 can be activated and controlled remotely from outside of RPV 52 via electrical control signals.

FIG. 7 is a cross-sectional side view of the control rod drive mechanism 88 , and FIG. 8 is a more detailed cross-sectional view of the single-hinge clasp assembly 138 used in the control rod drive mechanism 88 . 7 and 8 , a through hole 158 is provided in the drive shaft housing 77 and the nozzle 78 . A bolt (not shown) may be inserted into hole 158 to connect drive shaft housing 77 to nozzle 78 , which extends upwardly from the upper head of RPV 52 as shown in FIG. 2 . .

Disconnect rod 132 extends through the entire length of drive shaft 20 and a cylindrical disconnect magnet 134 is attached to the upper end of disconnect rod 132 . Disconnect magnet 134 extends upward into drive shaft housing 77 , and annular disconnect coil 136 extends around drive shaft housing 77 and disconnect magnet 134 . When activated, the disconnect coil 136 may hold the disconnect magnet 134 in an elevated position thereby retracting the disconnect rod 132 vertically upward within the drive shaft 20 .

The upper end of the drive shaft 20 includes a threaded outer surface 140 . In one example, thread 140 may include an ACME® type thread to linearly displace drive shaft 20 . Of course, any other type of thread or gearing may be used. Drive shaft 20 extends from below disconnect magnet 134 , through drive shaft housing 77 and nozzle 78 , to the upper head of RPV 52 ( FIG. 1 ). Drive shaft 20 extends through the length of RPV 52 , and its bottom end includes a grapple 126 connected to control rod assembly 80 . Disconnect magnet 134 and disconnect coil 136 surround disconnect assembly 120 .

The annular configuration of the drive coil 128 may extend around the outside of the drive shaft housing 77 , and the annular configuration of the drive magnet 130 inside the drive shaft housing 77 extends around the drive shaft 20 . can be The continuously activated driving coils 128 may raise the driving magnet 130 . The AC activation action of the AC drive coil 128 in FIG. 8 may also rotate the drive magnet 130 about the central axis 156 of the drive shaft 20 . The drive coil 128 , the drive magnet 130 , and the clasp assembly 138 form a drive assembly 122 .

A single-hinge clasp assembly 138 is coupled to the drive shaft housing 77 on its bottom end and to the drive magnet 130 at its top. The clasp assembly 138 includes an annular base 142 that includes a central opening extending around the drive shaft 20 . A lip 143 extends outwardly from the outer bottom end of the base 142 and sits in a recess formed between the bottom end of the drive shaft housing 77 and the top end of the nozzle 78 . The lip 143 serves as a hold-down holding base 142 that holds it down against the top surface of the nozzle 78 .

An annular collar 148 is rotationally attached to the base 142 and includes a step 144 attached to the top of the bearing 154 that extends around the top of the base 142 . The collar 146 also includes a central opening that receives and extends around the drive shaft 20 . The collar 146 remains vertical/raised on the base 142 , but rotates about the central axis 156 of the drive shaft 20 at the top of the bearing 154 and base 142 .

The outer end of the gripper 150 is pivotally attached to the upper end of the collar 148 with a first pin 152A. The inner end of the grip portion 150 is pivotally attached to the bottom end of the clasp 146 with a second pin 152B. The upper end of the clasp 146 is attached to the drive magnet 130 . The bottom end of the clasp 146 may rest on top of the step 144 of the collar 148 when the drive magnet 130 is lowered.

When activated, the drive coil 128 lifts the drive magnet 130 vertically upward to lift the latch 146 . Lifting the clasp 146 causes the inner end of the grip portion 150 to rotate upward to engage the thread 140 on the drive shaft 20 . The outer end of the grip portion 150 rotates about a pin 152A held vertically in place by a collar 148 .

After raising the inner end of the gripper 150 , the drive coil 128 may start rotating the drive magnet 130 about the central axis 156 of the drive shaft 20 . The bottom end of the drive magnet 130 begins to rotate the raised clasp 146 and attached gripper 150 around the outer circumference of the drive shaft 20 .

The rotating gripper 150 rotates the collar 148 over the top of the base 142 and about the central axis 156 while being held up and held in place by the base 142 .

The inner end of the gripper 150 rotates within the thread 140 to move the drive shaft 20 axially and linearly up within the nozzle 78 and drive shaft housing 77 . The driving coil 128 may rotate the driving magnet 130 in the opposite direction, and thus also rotate the gripping part 150 attached to the thread 140 in the opposite direction. Accordingly, the gripper 150 axially and linearly moves the drive shaft 20 upward or downward as commanded by the electrical control system.

Deactivating the drive coils 128 lowers the drive magnet 130 vertically down. The inner end of the grip portion 150 is rotated downwardly about the pin 152B to disengage from the thread 140 . The drive shaft 20 is now released from the grip portion 150 and freely descends vertically downward by gravity.

9 is a cross-sectional plan view of the drive assembly 122 . The annular drive coil 128 extends around the outer perimeter of the drive shaft housing 77 , and the annular drive magnet 130 extends around the inner perimeter of the drive shaft housing 77 . The drive shaft 20 extends through a central opening formed in the drive magnet 130 , and the disconnect rod 132 extends through a hole formed along the central axis of the drive shaft 20 . A thread 140 extends around the outer surface of the drive shaft 20 .

When continuously activated, the drive coil 128 generates an electromagnetic field that lifts the drive magnet 130 vertically upward. When the drive coil 128 is activated in an alternating pattern, the electromagnetic field also rotates the drive magnet 130 about its central axis, causing the drive assembly 122 to operate effectively like an electric motor. For example, the electrical control system may activate drive coil A during a first period and may activate drive coil B during an alternating second period. Drive coils A and B are alternately activated to cause drive magnet M to rotate about a vertical axis extending through drive shaft 20 .

10 is a top cross-sectional view of a single-hinge clasp assembly 138 . The disconnect rod 132 extends through the center of the drive shaft 20 . A thread 140 extends around the outer surface of the drive shaft 20 . The clasp 146 has an annular cross-sectional shape and is attached to the inner end of the grip portion 150 through a pin 152B. The collar 148 also has an annular cross-sectional shape and is attached to the outer end of the grip portion 150 via a pin 152A. As described above, the clasp 146 is attached to the drive magnet 130 and is movable up and down in the vertical direction. The drive shaft housing 77 also has an annular cross-sectional shape coaxially aligned with the drive shaft 20 . It should also be noted that any number of grippers 150 may be positioned around drive shaft 20 . For example, four grippers 150 may be positioned 90 degrees apart around the drive shaft 20 .

11A-11E are cross-sectional side views showing different operating positions of the control rod drive mechanism 88 . Referring to FIG. 11A , the drive assembly 122 is shown in a lowered state. With the drive coil 128 deactivated and the drive magnet 130 in the lowered position, the control rod assembly 80 is fully inserted into the reactor core 6 (FIG. 1). Lowered drive magnet 130 with attached clasp 146 released gripping portion 150 from thread 140 of drive shaft 20 .

During a forced SCRAM or loss of power, the drive coil 128 may be deactivated, causing the drive shaft 20, disconnected from the shackle assembly 138, to fall down by gravity. The attached control rod assembly 80 is thus lowered into the fuel assembly 90 to neutralize the reactor core 6 (see FIGS. 1 and 3 ). Thus, the CRDM 88 has the advantage of automatically scramming the reactor core 6 whenever it is deactivated during a power failure.

Disconnect assembly 120 is shown in a lowered state. The disconnect coil 136 is deactivated and the disconnect magnet 134 is seated on top of the drive shaft 20 in the lowered position. In the lowered position, the bottom end of the disconnect rod 132 extends between the reciprocating arms 127A, 127B of the grapple 126 . The spread out grapple arms 127A, 127B are pressed against and locked into grooves in the cylindrical hub 82 of the control rod assembly 80 .

11B shows the drive assembly 122 in an elevated position. The drive coil 128 is activated and the drive magnet 130 is in the raised position. The raised drive magnet 130 lifts the attached clasp 146 to move the inner ends of the grip portion 150 upward, and interlocks with the thread 140 of the drive shaft 20 . The locked grippers 150 may raise or lower the drive shaft 20 based on the rotation direction of the drive magnet 130 .

The disconnect assembly 120 is still in a lowered state, and the bottom end of the disconnect rod 132 is inserted and held between the grapple arms 127A, 127B. The spread out grapple arms 127A, 127B remain locked inside the cylindrical hub 82 to lock the bottom end of the drive shaft 20 to the control rod assembly 80 .

11C shows the drive assembly 122 in an elevated position. The drive coil 128 is activated and the drive magnet 130 is raised, moving the attached clasp 146 upward to engage the inner end of the grip portion 150 with the thread 140 . The drive coil 128 may begin to rotate the drive magnet 130 so that the gripping portion 150 may rotate around the engaged thread 140 of the drive shaft 20 . The rotating gripper 150 urges the drive shaft 20 into the drive shaft housing 77 in the axial and linear upward directions, and the connected control rod assembly 80 for reactivity insertion into the reactor core. Lift for a short distance (within the so-called dead band) that does not cause it.

Lifting the drive shaft 20 lifts the disconnect magnet 134 , holding the bottom end of the attached disconnect rod 132 between the grapple arms 127A, 127B. That is, lifting the drive shaft 20 and disconnect rod 132 together maintains the bottom end of the drive shaft 20 attached to the control rod drive mechanism 80 prior to disconnection as described below.

11D shows the drive assembly 122 in a lowered state and the disconnect assembly 120 in a raised state. When the drive shaft 20 and the disconnect magnet 134 are in the raised position shown in FIG. 11C , the disconnect coil 136 is activated. The drive coil 128 can then rotate the drive magnet 130 in the opposite direction to lower the drive shaft 20 vertically down. At the same time, the disconnect coil 136 holds the disconnect magnet 134 in the raised position. As the gripper 150 continuously moves the drive shaft 20 down linearly, the bottom end of the disconnect rod 132 slides out and up from between the grapples 126 . Grapple arms 127A, 127B are thus disengaged from control rod assembly 80 by reciprocating inward, which lowers a short distance. Alternatively, the drive coil 128 is deactivated to lower the drive shaft 20 and disconnect the control rod assembly 80 while the disconnect coil 136 holds the disconnect magnet 134 in the raised position.

11E shows both the disconnect assembly 120 and the drive assembly 122 in a lowered state. Deactivating the disconnect coil 136 disengages the disconnect magnet 134 causing the bottom end of the disconnect rod 132 to slide between the grapple arms 127A, 127B. The drive coil 128 can then be deactivated to disconnect the gripping portion 150 from the drive shaft 20 . Next, the spread grapple 126 is seated on the upper portion of the control rod assembly 80 .

Accordingly, the drive coil 128 and disconnect coil 136 can be remotely activated and deactivated during reactor core refueling operation to linearly displace the drive shaft 20 and also to displace the drive shaft 20 from the control rod assembly. Disconnect from (80). Reconnecting the control rod assembly 80 after the reassembly and refueling of the reactor vessel 52 is completed ( FIGS. 4A and 4B ) may be performed in the reverse order of the steps shown in FIGS. 11A to 11D .

Dual-Hinge Type Control Rod Drive Mechanism

12 is a side view of a double-hinge type control rod drive mechanism 159 . 13A and 13B are side cross-sectional views of the control rod drive mechanism 159 . 14 is a more detailed view of the double-hinge clasp assembly 160 .

12, 13A, 13B, and 14 , drive assembly 122 and disconnect assembly 120 in control rod drive mechanism 159 are substantially identical to those described above with drive and disconnect coils and magnets. includes The drive shaft housing 77 and nozzle 78 are also substantially identical to those described above. Disconnect rod 132 , drive shaft 20 and threaded outer surface 140 are also similar to those described above.

Similar to that described above, the continuously activated drive coil 128 raises the drive magnet 130 and aligns it with the annular drive coil 128 . Adjacent drive coils 128 may also be alternately activated to rotate the drive magnets 130 about the central axis 156 of the drive shaft 20 , such that the drive shaft 20 and attached control rod assembly 80 force linear motion.

The double-hinge clasp assembly 160 is coupled to the bottom end of the drive shaft housing 77 and coupled to the drive magnet 130 at the top end. The clasp assembly 160 includes a similar base 142 as described above, which includes a central opening extending around the drive shaft 20 . A similar lip 143 extends outwardly from the outer bottom end of the base 142 and sits in a recess formed between the bottom end of the drive shaft housing 77 and the top end of the nozzle 78 . The lip 143 serves as a hold-down holding base 142 that holds it down against the top surface of the nozzle 78 .

Referring to FIG. 13A , the drive assembly 122 is shown in an elevated position. Activating the drive coil 128 raises the drive magnet 130 and attached clasp 162 . The lower end of the gripper 164 moves upward and inward to engage the thread 140 of the drive shaft 20 . Then, based on the rotation direction of the drive magnet 130 , the locked gripper 164 may raise or lower the drive shaft 20 .

Disconnect assembly 120 is shown in a lowered position, and the bottom end of disconnect rod 132 is inserted between arms 127A, 127B of grapple 126 . The flared arms 127A, 127B lock on the inside of the cylindrical hub 82 to lock the bottom end of the drive shaft 20 to the control rod assembly 80 .

Referring to FIG. 13B , drive assembly 122 and disconnect assembly 120 are shown in a lowered state. Deactivating the drive coil 128 lowers the drive magnet 130 and attached clasp 162 .

The gripping portion 164 moves down and outwardly to disengage with the thread 140 of the drive shaft 20 .

Disconnect assembly 120 is still shown deactivated, and the bottom end of disconnect rod 132 is inserted and held between arms 127A, 127B of grapple 126 . The flared arms 127A, 127B remain locked inside the cylindrical hub 82 to lock the bottom end of the drive shaft 20 to the control rod assembly 80 .

In FIG. 14 , an annular collar 148 of a design similar to that of FIG. 8 is attached to the base 142 but is rotationally disengaged and attached to the top of a bearing 154 extending around the top of the base 142 . A similar step 144 is included. The collar 146 also includes a central opening that receives and extends around the drive shaft 20 . The collar 146 remains vertical/raised on the base 142 , but rotates about the central axis 156 of the drive shaft 20 at the top of the bearing 154 and base 142 .

The outer end of the hinge 168 is pivotally attached to the upper end of the collar 148 with a first pin 166A. The inner end of the hinge 168 is pivotally attached to the lower end of the grip portion 164 with a second pin 166B. The upper end of the clasp 162 is attached to the drive magnet 130 , and the bottom end of the clasp 162 is pivotally attached to the upper end of the gripper 164 with a third pin 166C.

When activated, the drive coil 128 lifts the drive magnet 130 vertically upward to raise the latch 162 as well. The grip portion 164 and the inner end of the hinge 168 also move upward, thereby engaging the thread 140 of the drive shaft 20 by moving the bottom end of the grip portion 164 inward.

After engaging the lower ends of the gripping portion 164 , the drive coil 128 may begin to rotate the drive magnet 130 about the central axis 156 of the drive shaft 20 . The bottom end of the drive magnet 130 also begins to rotate the raised clasp 146 and engaged gripper 164 around the drive shaft 20 . The rotating gripper 164 also rotates the collar 148 about a central axis 156 while being vertically restrained by the base 142 .

The inner end of the gripper 164 rotates within the engaged thread 140 to move the drive shaft 20 linearly up within the nozzle 78 and drive shaft housing 77 . The drive coil 128 may rotate the drive magnet 130 in opposite directions, thereby moving the drive shaft 20 axially down by rotating the gripping portion 164 in the opposite direction within the thread 140 .

Deactivating the drive coil 128 lowers the inner end of the grip portion 164 and the drive magnet 130 down. Hinge 168 also rotates down and outward to disengage the lower end of gripping portion 164 from thread 140 .

The drive shaft 20 is now released from the grip portion 150 and freely descends vertically down through gravity.

15 is a top cross-sectional view of the double-hinge clasp assembly 160 . The disconnect rod 132 extends through the centerline of the drive shaft 20 . A thread 140 extends around the outer surface of the drive shaft 20 . The clasp 162 has an annular cross-sectional shape and is attached to the upper end of the gripper 164 at the bottom end. Collar 148 also includes an annular cross-sectional shape and is attached to the outer end of hinge 168 via pin 166A. As described above, the collar 146 is attached to the drive magnet 130 and is movable up and down vertically. The drive shaft housing 77 also has an annular cross-sectional shape coaxially aligned with the drive shaft 20 .

16A-16G are simplified conceptual diagrams illustrating the different operations of the single-hinge type control rod drive mechanism 88 or the double-hinge type control rod drive mechanism 159 described above to achieve the CRDM function described herein. It focuses on the main elements to For descriptive purposes, the following abbreviations are used.

drive coil (128) = A

Driving magnet 130 = B

clasp (146, 162) = C

drive shaft (20) = D

Gripping parts 150 and 164 = E

Disconnect coil (136) = F

Disconnect Magnet (134) = G

Grapple (126) = H

Drive shaft housing (77) = I

Base 142 = J

Disconnect rod (132) = K

Control rod assembly (80) = CRA

The concentric electromagnetic coils A, F extend on the outside of the drive shaft housing I, which is also referred to as a pressure boundary. The outer coils (A, F) interact to move the cylindrical magnets (B, G) inside the pressure boundary (I), respectively.

Referring to FIG. 16A , electricity is not initially applied to the driving coil A. The clasp (C) is fixed to the annular drive magnet (B) and is seated on the base (J) inside the drive shaft housing (I).

Referring to FIG. 16B , power is applied to the driving coil A to lift the driving magnet B until it is aligned with the driving coil A. This lifts the clasp C and engages a gripper E that pivots around a pin fixed perpendicular to the inside of the pressure boundary I, but allows rotation of the clasp C. The gripping portion E fits into the threaded grooves of the drive shaft D.

Referring to FIG. 16C , by actuating the drive coil A in a specific sequence, the drive magnet B and the clasp C are set in rotational motion, while at the same time still maintained flush with the drive coil A. This precludes disengagement of the gripping portion E. The rotational motion of the gripper E is converted into a linear drive shaft motion to raise the drive rod D and the attached CRA.

Referring back to FIG. 16A , upon loss of power or SCRAM signal, the drive coil A releases the drive magnet B so that the gripper E moves downward and outward due to the lowering of the latch C. make it pivot This provides a safety feature whereby the gravity-induced descent of the drive shaft D lowers the attached CRA to the reactor core.

16D-16G show a method of remotely disconnecting the drive shaft D from the CRA prior to disassembly of the reactor pressure vessel 52 of FIGS. 4A and 4B . The driving coil (A) is initially not applied with power and the latch (C) is placed on the base (J). This may be similar to the initial drive shaft engagement configuration shown in FIG. 16A .

Referring to FIG. 16D , the drive coil A is activated to raise the drive magnet B and the shackle C and engage the grip portion E with the drive shaft D. As shown above in FIG. 11C , the driving coil (A) causes the driving magnet (B) and the clasp (C) to rotate while maintaining the same height as the driving coil (A). The rotating gripper (E) moves the drive shaft (D) and disconnection magnet (G) linearly upwards to the raised position, thereby causing the attached CRA to undergo a short distance (so-called dead band) that does not cause reactive insertion into the reactor core. within) is lifted.

Referring to FIG. 16E , power is still applied to the drive coil A to maintain the drive magnet B, the drive shaft D, the disconnect magnet G, and the disconnect rod K in an elevated position. Power is applied to the disconnection coil (F) to hold the disconnection magnet (G) and the attached disconnection rod (K) in place vertically. The drive coil A then rotates the drive magnet B, the clasp C, and the gripper E in opposite directions to linearly lower the drive shaft D. The grapple H on the bottom end of the drive shaft D holds the current CRA, and the bottom end of the disconnect rod K starts moving up and down from the grapple arm. The arm of the grapple H retracts, lowering the CRA a short distance until it rests on top of the nuclear fuel assembly upper nozzle 92 shown in FIG. 3 .

Referring to FIG. 16F , the drive coil A remains energized and thus holds the drive magnet B in place. After that, no power is applied to the disconnection coil (F). This releases the disconnect magnet G so that the bottom end of the disconnect rod K is inserted into the grapple H on the bottom of the drive shaft D to expand the grapple.

Referring to FIG. 16G , power is not applied to the driving coil (A) to release the annular driving magnet (B) and the clasp (C). The drive shaft (D) is lowered a short distance until the grapple (H) rests unengaged on top of the CRA cylindrical hub. This allows the upper and lower sections of the reactor pressure vessel to be separated for refueling without removing the CRA.

The re-connection of the grapple H to the CRA is performed in the reverse order. The drive coil (A) can move the drive shaft (D) and the disconnect magnet (G) to a vertically upwardly raised position. The disconnection coils (F) can be activated to hold the disconnection magnet (G) and disconnection rod (K) in a raised position. The drive coil A can then lower the drive shaft D to retract the grapple H and insert it into the CRA. The disconnect coil F may then be deactivated to lower the disconnect magnet G and the bottom of the disconnect rod K between the grapple H. Grapple (H) is extended and locked with CRA.

Alternatively, the grapple H uses the electromagnetic force of the disconnect coil F to pull the disconnect magnet G upward to re-engage with the CRA. The disconnection magnet (G) moves to the raised position without applying power to the drive coil (A) at the same time. The weight of the drive shaft D may be heavy enough so that only the disconnect rod K moves upwards inwardly of the drive shaft D. The grapple H is retracted and inserted into the CRA cylindrical hub. The disconnect coil F is then deactivated so that the bottom of the disconnect rod K is lowered down to the grapple H. Grapple (H) is extended and locked with CRA.

CRDM cooling system

17 shows a top cross-sectional view of a nuclear reactor module 5 with an exemplary control rod drive mechanism CRDM 88 having an integrated cooling system 180 . 18 is a three-dimensional perspective view showing the cooling system 180 and the CRDM 88 in more detail. The reactor module 5 includes the same upper containment vessel 76 housing, described above. A plurality of drive shaft housings 77 are located within an upper containment vessel 76 . As also described above, a plurality of drive shafts 20 extend downwardly into the RPV 52 via a nozzle 78 that connects at the top to the bottom end of the drive shaft housing 77 .

The drive shaft housing 77 may be any of the CRDM 88, disconnect assembly 120, drive assembly 122, single-hinge clasp assembly 138, or double-hinge type control rod drive mechanism 159 described above. can hold As described above, the drive assembly 122 can raise or lower the drive shaft 20 and the disconnect assembly 120 can disconnect the drive shaft 20 from the control rod assembly 80 (Fig. 3). Both drive assembly 122 and disconnect assembly 120 can be activated and controlled remotely from outside of RPV 52 via electrical control signals.

Also as noted above, any air or other gas in containment region 74 located between containment vessel 70 and reactor pressure vessel 52 may be removed or emptied during or prior to startup of the reactor. can get The gas evacuated or evacuated from containment vessel 74 may include non-condensable and/or condensable gases.

The cooling system 180 includes a series of heat fins 184 extending from the top of the drive coil 128 upwards and around the disconnect assembly 120 . The hot fins 184 may be provided in a flat shape and may be formed of any heat sink material, such as aluminum, copper, stainless steel, or any other heat conducting metal. Hot fins 184 have an improved path for radiant heat transfer to the CNV surface having a cooler temperature in containment region 74 formed between RPV 52 and CNV 70 . The hot fins 184 may remove heat generated by the drive coil 128 without substantially increasing the footprint of the CRDM 88 .

In one example, the hot fins 184 may be formed or attached with an external metal enclosure 185 that holds the drive coils 128 . For example, drive coil 128 and hot fins 184 may be formed as an annular enclosure of the same module that may slide along drive shaft housing 77 .

19 is a cross-sectional plan view of a lower portion of the CRDM cooling system 180 . 9 above, the annular drive coil 128 extends around the outer circumference of the drive shaft housing 77 and the annular drive magnet 130 extends around the inner circumference of the drive shaft housing 77 . do. The drive shaft 20 extends through a central opening formed in the drive magnet 130 , and the disconnect rod 132 extends through a hole formed along the central axis of the drive shaft 20 . A thread 140 extends around the outer surface of the drive shaft 20 .

Cooling channels 186 extend vertically through and/or between drive coils 128 and form or retain heat pipes 190 . For example, channel 186 may hold a metal tube holding a fluid that works together as heat pipe 190 . In this example, four pairs of outer heat pipes 190A and inner heat pipes 190B extend half-loop through each drive coil 128 . Outer heat pipe 190A and inner heat pipe 190B are alternatively referred to as heat pipe 190 .

20 is a top plan view of an upper portion of the CRDM cooling system 180 , and FIG. 21 is an enlarged plan cross-sectional view of an upper portion of the CRDM cooling system 180 . Cooling channels 188 extend vertically through hot fins 184 and form or retain tubes that in turn act as heat pipes 190 . The cooling channel 188 is formed continuously or connected with the channel 186 in the drive coil 128 to form a heat pipe loop 190 .

5-7 above, a cylindrical disconnect magnet 134 is attached to the upper end of the disconnect rod 132 (FIG. 7). Disconnect magnet 134 extends upward into drive shaft housing 77 , and annular disconnect coil 136 extends around drive shaft housing 77 and disconnect magnet 134 . The hot fins 184 extend radially outward from the disconnect coil 136 and include an upper section of the heat pipe 190 in one example. Heat pipes 190A, 190B extend half-loop upwards through respective hot fins 184 .

Evaporative sections of heat pipes 190A, 190B extend along the inside of hot fins 184 and are covered with insulation 196 of hot fins 184 . In one example, the insulation 196 may be any type of mineral wool, calcium silicate, fiberglass, microporous refractory, glass fiber felt, It can be reflective metallic insulation (RMI) or any other material commonly used for insulating pipes in nuclear power plants.

The condensing sections of the heat pipes 190A, 190B are fluidly coupled to the insulating sections of the heat pipes 190A, 190B and extend along the outer side of the heat fins 184 and are surrounded by the condensing channels 198 . In one example, the condensing channel 198 is a group of highly thermally conductive metal strips or slots extending radially outward from the outer surface of the heat pipe 190 . The condensing channel 198 exposes more of the outer surface area of the condensing section of the heat pipe 190 to the cooler containment area 74 defined by the CNV 70 . Any other type of hot fins or hot needles may be formed in the hot fins 184 around the condensing portion of the heat pipe 190 to further increase the rate of heat transfer.

22 is a three-dimensional cross-sectional side view of the cooling system 180 , and FIG. 23 is a more specific three-dimensional cross-sectional side view of the cooling system 180 . In this example, multiple pairs of outer and inner circular heat pipe loops 190A, 190B extend through respective drive coils 128 and hot fins 184 respectively. Outer heat pipes 190A extend along the inner and outer sides of hot fins 184 and drive coils 128 . The inner heat pipe 190B extends through the hot fins 184 and the drive coil 128 inside the outer heat pipe 190A.

The heat pipe 190 extends upward through the top end of the drive coil 128 from the bottom end, and then further extends through the bottom end to the top end of the hot fin 184 . The upper end of the heat pipe 190 extends radially outward from the disconnect coil 136 and the bottom end of the heat pipe 190 radially inwardly toward the drive shaft housing 77 forming a continuous loop. is extended

An alternative option is to mount the cooler upper section 194 of the heat pipe 190 directly to the inner wall of the CNV 70 above the CRDM 88, and the heat is transferred to the CNV surface by conduction. For example, the heat pipe 190 may include a loop that further extends over or out of the top of the hot fins 184 or drive coil 128 and contacts the inner wall of the CNV 70 . In both alternatives, when heat is transferred to the CNV, it is dissipated into the CNV's external environment.

The inner portion of the heat pipes 190A, 190B positioned adjacent the inner side of the hot fin 184 and drive coil 128 is referred to as the vaporization section 208 and extends adjacent the outer side of the hot fin 184 . The outer portion of the heat pipes 190A, 190B is referred to as the condensing section 210 . Evaporation section 208 and condensation section 210 are fluidly coupled together.

Heat pipe 190 may include any round, oval, or flat shaped tube or orifice formed of any material, such as copper, aluminum, stainless steel, or any other thermally conductive metal. Heat pipe 190 may comprise any fluid 200 capable of transferring heat, such as water, ammonia, methanol, liquid sodium or the like. When heated, the fluid 200 may be transformed into the vaporized state 200A, and when cooled, it may be transformed back to the condensed state 200B.

Evaporation and condensation of fluid 200 creates a fluid flow through heat pipe 190 that removes heat from drive coil 128 . For example, drive coil 128 generates heat that evaporates fluid 200A during operation. Evaporated fluid 200A rises through evaporation section 208 of heat pipe 190 to transfer heat from drive coil 128 .

As described above, the insulating material 196 of the upper condensing section 210 of the heat pipe 190 carries the evaporated fluid 200A. The condensing channel 198 of the upper condensing section 210 of the heat pipe 190 condenses the evaporated fluid 200A into droplets of the condensed fluid 200B. Other types of porous media may be used in the heat pipe 190 to condense the evaporated fluid 200A into the condensed fluid 200B.

The condensed fluid 200B falls vertically downward through the condensing section 210 of the heat pipe 190 by gravity or capillary action. Drive coil 128 then reheats condensed fluid 200B to become evaporative fluid 200A, which recirculates back through heat pipe 190 and further removes heat from drive coil 128 . A flow restrictor (not shown) may be located in the heat pipe 190 upstream of the drive coil 128 to control the flow rate and flow direction of the fluid 200 .

Passive cooling system 180 reduces or eliminates the number of water hoses, piping, and water pumping equipment typically used in active RCCWS systems. The simplified cooling system 180 also incorporates the heat pipe 190 in an integrated drive coil 128 and hot fins 184, so that the electric drive coil 128 can be replaced more easily during maintenance operations. (88) Provide design. The cooling system 180 also overcomes the limitations of convective thermal cooling in pressurized water reactor (PWR) CRDM designs where the CRDM electrical coil 128 is disposed outside of the CRDM pressure boundary in a vacuum environment.

While the principles of the preferred embodiment have been described and shown, it will be apparent that the embodiments may be changed in construction and detail without departing from such principles. All modifications and improvements falling within the scope and spirit of the following claims will be made.

Some of the operations described above may be implemented in software and other operations may be implemented in hardware. One or more of the acts, processes, or methods described herein may be performed by an apparatus, apparatus, or system similar to that described herein with reference to the accompanying drawings.

It will be apparent to one skilled in the art that the disclosed embodiments may be practiced without some or all of the specific details provided. In other instances, specific processes or methods have not been described in order to avoid unnecessarily obscuring the disclosed implementations. Other implementations and applications are possible, so the following examples should not be considered limiting or limiting in scope and setting.

Reference has been made to the accompanying drawings, which form a part of the specification and illustrate specific implementations by way of illustration. Although the disclosed embodiments have been described in sufficient detail to enable those skilled in the art to practice them, it is to be understood that these examples are not limited, and thus other embodiments may be used without departing from the spirit and scope of the invention. Changes may be made to the disclosed embodiments.

While the examples provided herein have primarily described a pressurized water reactor and/or a light water reactor, it will be apparent to those skilled in the art that these examples may be applied to other types of power systems. For example, a boiling water reactor, a sodium liquid metal reactor, a gas cooled reactor, a pebble-bed reactor, and/or other types of reactor designs with embodiments and their The deformation may be made operatively.

It should be noted that the embodiments are not limited to any particular type of reactor cooling mechanism, or to any particular type of fuel employed to produce heat in or in connection with a nuclear reaction. Any ratios or values described herein are provided by way of example only. Other ratios and values may be determined experimentally by scale models of nuclear reaction systems or complete full-scale structures.

Claims (20)

A cooling system for a reactor control rod drive mechanism (CRDM), comprising:
Evaporation section located inside or next to the CRDM;
a condensation section fluidly coupled to the evaporation section; and
a fluid that evaporates while in the evaporation section with heat generated by the CRDM, flows from the evaporation section to the condensing section, travels away from the CRDM, and condenses while in the condensing section to be recirculated back to the evaporation section. system. According to claim 1,
A cooling system comprising a series of hot fins extending upwardly from the drive coil of the CRDM, an evaporation section extending through the inner portion of the hot fins and drive coil, and a condensing section extending through the hot fins and an outer portion of the drive coil. 3. The method of claim 2,
and the hot fins extend around the disconnect coil configured to electromagnetically retain the disconnect magnet of the CRDM. 3. The method of claim 2,
and the drive coil and hot fins form an elongate annular shape around the annular drive shaft housing. 3. The method of claim 2,
A cooling system comprising a heat pipe extending into a loop through a hot fin and a drive coil. 6. The method of claim 5,
A cooling system comprising: an insulation formed around an inner portion of a heat pipe positioned on the hot fin. 7. The method of claim 6,
A cooling system comprising a condensing channel formed around an outer perimeter of a heat pipe located at the hot fin. 6. The method of claim 5,
wherein the heat pipe extends from the CRDM to the inner surface of the vessel containing the nuclear reactor or to a structure that conducts heat to the environment outside of the vessel containing the nuclear reactor. According to claim 1,
CRDM is
a drive coil positioned around an outer surface of the drive shaft housing;
a drive magnet positioned around the inner surface of the drive shaft housing;
a drive shaft connected to the drive magnet at an upper end and a drive shaft connected to the nuclear control rod assembly at a lower end;
Activating the drive coil raises the drive magnet to raise the drive shaft and nuclear control rod assembly, and the cooling system removes heat generated by the drive coil while raising the drive shaft and nuclear control rod assembly. A cooling system for a reactor control rod drive mechanism (CRDM), comprising:
a drive shaft housing extending upwardly from an upper end of the reactor pressure vessel;
a drive shaft having a top end extending into the drive shaft housing and a bottom end coupled to a control rod assembly located at the bottom end of the reactor pressure vessel;
a drive mechanism coupled to the drive shaft housing configured to linearly displace the drive shaft and raise and lower the control rod assembly;
a heat pipe located inside or next to the drive mechanism; and
a fluid located in the heat pipe configured to circulate through the heat pipe by evaporation and condensation to remove heat from the drive mechanism. 11. The method of claim 10,
A cooling system comprising a hot fin extending upwardly from the drive mechanism, wherein the heat pipe extends through the hot fin and the drive mechanism. 12. The method of claim 11,
A cooling system comprising: an insulation at least partially surrounding an interior portion of the heat pipe extending through the hot fins. 13. The method of claim 12,
and a condensing channel at least partially surrounding the outside of the heat pipe extending through the hot fins. 12. The method of claim 11,
wherein the heat pipes extend upwardly through the drive mechanism and the hot fins and further down through the drive mechanism and the hot fins forming a loop. 12. The method of claim 11,
wherein the hot fins extend vertically upward from the drive mechanism and radially outwardly from the drive shaft housing. 11. The method of claim 10,
A cooling system, comprising: a containment vessel at least partially encapsulating the reactor pressure vessel, wherein the heat pipe extends outwardly from the drive mechanism to an interior surface of the containment vessel. A system for cooling a control rod drive mechanism (CRDM) in a nuclear reactor, comprising:
a pipe containing a fluid;
the pipe
an evaporation section located inside or next to the CRDM, wherein the fluid in the evaporation section is configured to evaporate with heat generated by the CRDM; and
a condensation section fluidly coupled to the evaporation section configured to condense the evaporated fluid and circulate the condensed fluid back to the evaporation section via gravity or capillary action. 18. The method of claim 17,
and a hot fin extending outwardly from the drive coil of the CRDM, wherein the pipe forms a loop extending through the hot fin and the drive coil. 19. The method of claim 18,
The evaporation section of the pipe extends along the inner portion of the drive coil and the inner portion of the hot fin, and the condensing section of the pipe extends along the outer portion of the drive coil and the outer portion of the hot fin. 20. The method of claim 19,
an insulation surrounding at least a portion of the pipe extending along the interior portion of the hot fin; and
a condensing channel surrounding at least a portion of the pipe extending along an outer portion of the hot fin.

Images