WO2011051751A1 - Radioactive debris trap - Google Patents
Radioactive debris trap Download PDFInfo
- Publication number
- WO2011051751A1 WO2011051751A1 PCT/IB2009/007544 IB2009007544W WO2011051751A1 WO 2011051751 A1 WO2011051751 A1 WO 2011051751A1 IB 2009007544 W IB2009007544 W IB 2009007544W WO 2011051751 A1 WO2011051751 A1 WO 2011051751A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- debris trap
- radioactive
- trap
- debris
- steam generator
- Prior art date
Links
- 230000002285 radioactive effect Effects 0.000 title claims abstract description 63
- 230000005855 radiation Effects 0.000 claims abstract description 6
- 239000007788 liquid Substances 0.000 claims abstract description 4
- 239000012530 fluid Substances 0.000 claims description 8
- 239000002184 metal Substances 0.000 claims description 8
- 230000000295 complement effect Effects 0.000 claims description 4
- 239000002245 particle Substances 0.000 description 18
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 11
- 239000002826 coolant Substances 0.000 description 5
- 230000008901 benefit Effects 0.000 description 4
- 238000009434 installation Methods 0.000 description 4
- 230000003134 recirculating effect Effects 0.000 description 4
- 239000010419 fine particle Substances 0.000 description 3
- 238000000926 separation method Methods 0.000 description 3
- XLYOFNOQVPJJNP-ZSJDYOACSA-N Heavy water Chemical compound [2H]O[2H] XLYOFNOQVPJJNP-ZSJDYOACSA-N 0.000 description 2
- 239000000446 fuel Substances 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- 239000012634 fragment Substances 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- -1 i.e. Substances 0.000 description 1
- 230000003116 impacting effect Effects 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
- 239000002901 radioactive waste Substances 0.000 description 1
- 230000003068 static effect Effects 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 230000008685 targeting Effects 0.000 description 1
- 230000005514 two-phase flow Effects 0.000 description 1
- 238000011144 upstream manufacturing Methods 0.000 description 1
- 238000005303 weighing Methods 0.000 description 1
Classifications
-
- 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
- G21C19/42—Reprocessing of irradiated fuel
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D21/00—Separation of suspended solid particles from liquids by sedimentation
- B01D21/0003—Making of sedimentation devices, structural details thereof, e.g. prefabricated parts
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D35/00—Filtering devices having features not specifically covered by groups B01D24/00 - B01D33/00, or for applications not specifically covered by groups B01D24/00 - B01D33/00; Auxiliary devices for filtration; Filter housing constructions
- B01D35/02—Filters adapted for location in special places, e.g. pipe-lines, pumps, stop-cocks
- B01D35/027—Filters adapted for location in special places, e.g. pipe-lines, pumps, stop-cocks rigidly mounted in or on tanks or reservoirs
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D21/00—Separation of suspended solid particles from liquids by sedimentation
- B01D21/0039—Settling tanks provided with contact surfaces, e.g. baffles, particles
- B01D21/0042—Baffles or guide plates
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D21/00—Separation of suspended solid particles from liquids by sedimentation
- B01D21/24—Feed or discharge mechanisms for settling tanks
- B01D21/2427—The feed or discharge opening located at a distant position from the side walls
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D35/00—Filtering devices having features not specifically covered by groups B01D24/00 - B01D33/00, or for applications not specifically covered by groups B01D24/00 - B01D33/00; Auxiliary devices for filtration; Filter housing constructions
- B01D35/30—Filter housing constructions
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F22—STEAM GENERATION
- F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
- F22B37/00—Component parts or details of steam boilers
- F22B37/002—Component parts or details of steam boilers specially adapted for nuclear steam generators, e.g. maintenance, repairing or inspecting equipment not otherwise provided for
-
- 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
- G21C19/28—Arrangements for introducing fluent material into the reactor core; Arrangements for removing fluent material from the reactor core
- G21C19/30—Arrangements for introducing fluent material into the reactor core; Arrangements for removing fluent material from the reactor core with continuous purification of circulating fluent material, e.g. by extraction of fission products deterioration or corrosion products, impurities, e.g. by cold traps
- G21C19/307—Arrangements for introducing fluent material into the reactor core; Arrangements for removing fluent material from the reactor core with continuous purification of circulating fluent material, e.g. by extraction of fission products deterioration or corrosion products, impurities, e.g. by cold traps specially adapted for liquids
-
- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21D—NUCLEAR POWER PLANT
- G21D1/00—Details of nuclear power plant
- G21D1/006—Details of nuclear power plant primary side of steam generators
-
- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21F—PROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR
- G21F9/00—Treating radioactively contaminated material; Decontamination arrangements therefor
- G21F9/04—Treating liquids
-
- 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
-
- 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
Definitions
- the present invention relates generally to the field of nuclear reactors and in particular to a radioactive debris trap to be installed in the primary outlet plenum of a steam generator for removing fine particles and chips of metal from the primary heat transport system of a nuclear power plant.
- Each RSG is a vertical shell, inverted U-tube heat exchanger with steam-water separation equipment located above the tube bundle inside the upper shell (or steam drum).
- a cylindrical shroud or bundle wrapper surrounds the tube bundle separating it from the lower shell. This creates an annular region which serves as the downcomer to return the recirculated water from the steam separators to the tube bundle inlet at the bottom of the unit.
- a feed ring type RSG generally designated 100 as illustrated in FIG.
- feedwater is introduced by a nozzle and header to the top of the downcomer, and flows with the separator return flow down and into the tube bundle.
- feed flow enters the steam generator through a nozzle and feedwater distribution box to the baffled section at the cold leg outlet end of the tube bundle where it is heated to saturation before joining with the hot leg riser flow within the tube bundle.
- the flow configuration and the major design features of a typical feed ring type RSG are as follows.
- the hot primary coolant enters a portion of the vessel primary head 1 10, via primary inlet nozzle 120, which is separated into two plenums 130, 140 by a divider plate 50.
- the primary coolant flows through the inside of the U-tube bundle 150 and exits the steam generator 100 through the primary head outlet plenum 140 and primary outlet nozzle 160.
- the U-tubes make a continuous 180 degree bend at the top of the tube bundle.
- secondary-side feedwater enters the upper shell 170 via feedwater nozzle 180 and is conveyed to a feed ring (not shown) and is mixed with water returning from the steam-water separation equipment 190 located in the upper shell 170.
- the water flows down the downcomer annulus between the shroud and the shell to the tubesheet where it enters the tube bundle.
- the secondary-side water is heated as it passes up through the tube bundle generating steam through nucleate boiling heat transfer, creating a two-phase flow.
- PHT primary coolant loop
- debris can sometimes begin to accumulate in the primary coolant loop or primary heat transport (PHT) system of such steam generators 100.
- PHT primary heat transport
- the type of debris which can typically be found in a PHT system can measure 1 square mm or less, or the debris fragments can be as large as 2 mm wide by 4 mm long. Damage and defects caused by debris can cause a problems for nuclear power plants. Thus, it logically follows that various debris trapping devices have been developed in response to the industry wide problems caused by debris.
- U.S. Patent No. 4,684,496 to Wilson et al. (“Wilson”) describes a debris trap for a pressurized water nuclear reactor to be installed into the reactor vessel itself.
- the debris trap disclosed in Wilson is mounted within a bottom nozzle of a fuel assembly so as to capture and retain debris carried by coolant flowing from the lower core plate openings of a nuclear reactor to a fuel assembly and is made up of a plurality of straps aligned with one another in a crisscross arrangement.
- a simple debris trap which can remove a greater amount of debris and reduce the problems caused by debris.
- One aspect of the present invention is drawn to a radioactive debris trap that is capable of targeting and removing a higher than average concentration of debris particles, i.e., fine particles and chips of metal, from a nuclear power plant's primary heat transport (PHT) system without disrupting all of the primary flow the system.
- Another aspect of the present invention is drawn to a simple yet effective radioactive debris trap which can be installed in any type of steam generator.
- one aspect of the present invention is drawn to a radioactive debris trap configured to be installed in a steam generator for the purpose of removing debris which is entrained in a primary flow of a nuclear power plant's PHT system.
- the debris trap is made entirely of metal and includes an outer cylinder having an outer surface, a top end and a bottom end having a perimeter.
- the invention also includes a coaxial inner cylinder located within the outer cylinder.
- the inner cylinder includes a top end and a bottom end. Additionally, a top plate connects the top end of both the outer cylinder and the inner cylinder.
- a plurality of small holes is located at the top end of the outer cylinder. Liquid contained in the primary flow exits the debris trap through these holes. Also, the plurality of holes are sized to ensure that the gravitational force exerted on the debris entrained in the primary flow is larger than the upward drag force exerted on that debris by the flow itself.
- the debris trap of the present invention includes an annular cavity which is located between the outer cylinder and the inner cylinder.
- the annular cavity contains a settling chamber positioned below the plurality of small holes.
- a bottom plate encloses the radioactive debris trap and is connected to the perimeter of the bottom end of the outer cylinder.
- a gap is located between the bottom end of the inner cylinder and the bottom plate. Primary flow with debris entrained therein enters the settling chamber through this gap.
- the present invention also includes a means for fixedly connecting the radioactive debris trap to the steam generator which is fixedly attached to the outer surface of the outer cylinder on the back side of the debris trap.
- a means for removing the radioactive debris trap from the steam generator without exposing personnel to excessive radiation is provided on the front side of the debris trap.
- the preferred embodiment for this means includes three female support brackets which are triangularly arranged with respect to each other and which include an uppermost centrally positioned female support bracket.
- the means for removing the radioactive debris trap from the steam generator also includes a remote robotic arm which is configured with three complementary male support brackets which engage the female support brackets attached to the front of the debris trap.
- FIG. 1 is a schematic cross sectional view of a recirculating steam generator having a primary heat transport system, and showing an example of where the radioactive debris trap of the present invention can be installed;
- FIG. 2 is a perspective view of a radioactive debris trap according to the preferred embodiment of the present invention.
- FIG. 3 is a sectional view of the debris trap of FIG. 2, viewed in the direction of arrows 3 - 3 of FIG. 2;
- FIG. 4 is a perspective view of a radioactive debris trap according to another embodiment of the present invention.
- FIG. 4A is a sectional view of the debris trap of FIG. 4, viewed in the direction of arrows 4A - 4A of FIG. 4;
- FIG. 5 is a perspective view of the support for the radioactive debris traps illustrated in FIGS. 2, 3, 4 and 4A, as located on a divider plate of a recirculating steam generator;
- FIG. 6 is a schematic cross sectional view showing the debris trap's lower female support bracket connected to the base support plate's male support bracket;
- FIG. 6A is a schematic cross sectional view showing the debris trap's upper female support bracket connected to the base support plate's male support bracket;
- FIG. 7A is a side view of a hex head locking tab bolt
- FIG. 7B is a top view of a hex head locking tab bolt with the locking tabs in the open, unfolded position
- FIG. 8 is a conceptual perspective view of a remote tooling robotic arm used to install or remove the embodiments of the present invention.
- FIGS. 2 and 3 show a preferred embodiment of the radioactive debris trap 10 of the present invention.
- the present invention can be installed in the primary head of a U-tube type recirculating steam generator (RSG) 100 for removing fine particles and chips of metal from a primary flow 46 of a nuclear power plant's primary heat transport (PHT) system.
- RSG U-tube type recirculating steam generator
- PHT primary heat transport
- the preferred embodiment of the radioactive debris trap 10 which has a front side and a back side includes an outer cylinder 12 and a coaxial inner cylinder 14 positioned within the outer cylinder 12. Both the outer cylinder 12 and the inner cylinder 14 have a top end as well as a bottom end and the outer cylinder 12 has an outer surface. Additionally, a conical top plate 16 connects the outer metallic cylinder 12 to the inner metallic cylinder 14. The top plate 16 functions to direct debris toward the trap 10 and to prevent any particles from exiting the top of the trap 10. Alternatively, the top plate 16 can be a planar surface which may be flat or inclined
- a bottom plate 18 is attached to the entire perimeter of the bottom end of the outer cylinder 12 and hence closes the entire bottom of the trap 10.
- a means for fixedly connecting the radioactive debris trap 10 to the steam generator 100, preferably to the divider plate 50, is fixedly attached to the outer surface of the outer cylinder 12 on the back of the debris trap 10.
- FIG. 2 shows three female support brackets 20 which are fastened to the outer surface of the outer cylinder 12. These female support brackets 20 are also triangularly arranged with respect to each other. The three female support brackets 20 serve the purpose of facilitating attachment to the steam generator 100 divider plate 50 shown in FIG. 1. However, other means of attachment may be used.
- such means could include male support brackets 32, similar to those shown in FIG. 5 and discussed in greater detail below, which are attached to the debris trap 10 and which are designed to engage with female supports.
- a design which uses bolted connections is another potential means of attaching the debris trap 10 to the steam generator 100.
- a similar set of support brackets 20 are provided on an opposite side of the debris trap 10 to facilitate its installation and removal using either manual or robotically controlled tooling, as described later in this specification.
- a plurality of small holes 24 which are sized to ensure low upward velocity in the settling chamber are located at the top end of the outer cylinder 12. Liquid contained in the flow 46 exits the debris trap 10 through these holes 24, while debris swept into the debris trap 10 along with the primary flow 46 remains trapped therein.
- the preferred embodiment of the radioactive debris trap 10 includes a gap 22a which is located between the bottom of the inner cylinder 14 and the bottom plate 18. This gap 22a allows the flow 46 to sweep the debris particles outward into a settling chamber 48 which is located in an annular cavity positioned between the outer cylinder 14 and the inner cylinder 12. As explained in more detail below, upward fluid velocity in the settling chamber is kept below the settling velocity to cause the debris that enters the debris trap 10 to settle out and remain in the settling chamber 48 or on the bottom plate 18.
- the preferred embodiment of the debris trap 10 is made entirely of steel of a grade suitable to withstand the temperatures, stresses, flow conditions and chemistry conditions encountered in the steam generator.
- FIGS. 4 and 4A illustrate another embodiment of the debris trap 10 according to the present invention.
- the embodiment shown in FIGS. 4 and 4A includes an open-topped box 36 having a bottom 38, a front side 40, a back side 42, a right side and a left side.
- the front side 40 of the open-topped box 36 has a top end and a bottom end and a back side 42 of the open-topped box 36 has a top end, a bottom end as well as an outer surface.
- FIG. 4 shows the open-topped box 36 having a rectangular shape, the debris trap 10 can take any shape which will not prevent it from accomplishing its desired function.
- the open-topped box 36 can be square.
- FIGS. 4 and 4A also includes an angled plate 44 located inside the open-topped box 36.
- the angled plate 44 is positioned to direct the flow 46 and the debris entrained therein into the debris trap 10 and it has a front end, a right side, a left side and a back end.
- the front end of the angled plate is fixedly attached to the front side 40 of the open-topped box 36 and is flush with the top end of the box 36.
- the right and left sides of the angled plate 44 are fixedly attached to the right side of the open-topped box 36 and the left side of the open- topped box 36 respectively.
- the back end of the angled plate 44 is proximate yet unconnected to both the bottom of the open-topped box 36 and the back side 42 of the open-topped box 36.
- FIGS. 4 and 4A includes a means for fixedly attaching the radioactive debris trap 10 to the steam generator divider plate 50 attached to the outer surface of the back side 42 of the open-topped box 36, as well as means for facilitating its installation and removal using either manual or robotically controlled tooling, as described later in this specification.
- FIG. 4 shows the three female support brackets 20 fastened to the back surface 42 of the debris trap 10.
- the debris trap 10 of the present invention is designed to employ the same arrangement of female support brackets 20 on the front as well as the rear of the trap 10 to securely engage the male support brackets 32 on both the- debris trap support 26 for attachment as well as on a robotic arm R removal tool, discussed below. Additionally, more or fewer support brackets 20 could be used. Alternatively, male support brackets 32 could be attached to the debris trap 10 which are designed to engage with female support brackets 20. Also designs using bolted connections are another potential means of attaching the trap 10 to the steam generator. [0033] Additionally as illustrated in FIGS.
- both of the above mentioned embodiments of the present invention may include a bolt 70 and a locking tab 74 for engaging the bolt hex head 72 to ensure the trap 10 cannot move upwards and become disengaged from the steam generator divider plate 50.
- the bolt 70 may not be required if analysis and flow conditions indicate that upward movement of the debris trap 10 is unlikely.
- the locking tab 74 is fabricated from sheet metal.
- the uppermost center bracket of both the male brackets 32 and the female brackets 20 are fitted with a pilot hole 60 to engage the bolt 70.
- the locking tab 74 includes a lip to fold over the edge of the male or female bracket 32, 20 so the bolt 70 cannot turn.
- the bolt 70 can also be welded to the brackets 20, 32 or to a plate so it will not turn and then bent over the hex head portion 72 of the bolt 70 to prevent the bolt 70 from turning. Also as seen in FIGS. 6 and 6A, an angle is machined on the face of the support brackets 20, 32 to ensure a snug fit.
- the embodiment of the present invention shown in FIG. 4 also includes a plurality of small holes 24 positioned across the top of the front face 40 of the open top box 36. These small holes 24 are positioned on top of the settling chamber 48 and as explained in more detail below, they are sized to ensure low velocities in the settling chamber 48.
- All embodiments of the debris trap 10 of the present invention are securely fixed to a support bracket that is welded or bolted to an existing divider plate 50 in a steam generator 100 as shown in FIG. 1.
- the divider plate 50 is attached to the side of the primary head and to the bottom of the tubesheet and directs the flow 46 from the primary inlet nozzle 120 through the U-tubes 150 in the steam generator 100 back into the primary outlet plenum 140 and into the primary outlet nozzle 160.
- the support bracket can be designed to use existing bolting arrangement holes.
- the inventive debris trap 10 is securely fixed to a means for connecting the debris trap 10 to the divider plate 50 or at another location in the primary outlet plenum 140 of the steam generator 100.
- this means is attached to the outer surface of the outer cylinder 12.
- this means is attached to the outer surface of the back side 42 of the open-topped box 36.
- the means for attaching the trap 10 to a steam generator may take the form of a debris trap support base plate 28 which has a back surface that is fixedly attached to a divider plate 50 of the steam generator 100.
- the debris trap support base plate 28 as shown in FIG. 5 also includes three male support brackets 32 which supports the debris trap 10 and are designed to engage with the female support brackets 20 shown in FIGS. 2, 3, 4 and 4A.
- the preferred embodiment includes angled faces on the male and female support brackets 32, 20 to ensure a snug fit. As described above, fasteners may be required to secure the debris trap 10 to the debris trap support base plate 28.
- the preferred embodiment for the fastener is a bolt with a thin sheet metal locking tab, which is required to ensure the bolt does not come loose, that is screwed to a threaded connection on the upper male support bracket and hence ensures the trap cannot move upwards and become disengaged from the supports. Any reasonable means of attachment which is sufficiently strong can be used, if required.
- FIG. 5 shown in FIG. 5 are four pilot holes 34 which could accommodate fasteners such as bolts or rivets.
- the preferred embodiment would be bolts with locking tabs as this design has proven operating experience.
- the trap 10 can be welded to the divider plate 50, but this would make removal more difficult. It will be appreciated that while FIG. 5 illustrates a debris trap support base plate 28 suitable for the FIG. 4 and 4A embodiment, support brackets on the debris trap support base plate 28 suitable for the FIG. 3 embodiment would be angled or curved as necessary to accommodate the curved outer surface of the debris trap 10.
- both embodiments of the inventive debris trap 10 discussed include three female support brackets 20b attached to their front sides to facilitate removal using remote tooling, such as a long rod or a robotic arm R fitted with male brackets 32 (see FIG. 8) which are complementary to the female support brackets 20b and which are designed to engage the female support brackets 20b.
- remote tooling such as a long rod or a robotic arm R fitted with male brackets 32 (see FIG. 8) which are complementary to the female support brackets 20b and which are designed to engage the female support brackets 20b.
- additional remote tooling consisting of a long rod or a robotic arm with an impacting hammer that can apply a vibratory force to the bottom of the debris trap 10 may be required to loosen the connection between the male and female support brackets 32, 20.
- other suitable devices which can safely remove the debris trap 10 without exposing personnel to excessive radiation may be used.
- a robotic arm R with a clamping device could be used that would apply a force to the side of the debris trap 10 could be used. If
- the operating principle for the debris trap 10 is to allow the flow 46 containing the debris to enter the top of the debris trap 10 and enter the settling chamber 48 through the gap 22a or the slot 22b. After fluid enters the trap 10 it changes direction before it flows slowly upwards and exists through the plurality of small holes 24 near the top of the trap 10.
- the vertical velocity of the flow 46 in the trap 10 after the flow 46 turns upwards is less than the settling velocity the particle will stay in the trap 10.
- the condition which causes retention of the particles within the trap 10 is the downward force on the particle due to gravity being larger than the upward drag force on the particle exerted by the flow 46 of primary fluid within the debris trap 10.
- the pressure differential available to cause flow 46 in the debris trap10 is a function of fluid impingement velocity and the lower static pressure at the exit of the plurality of small holes 24.
- the multiple small holes located near the top of the settling chamber 48 are sized to control the upward velocity in the settling chamber to less than the particle settling velocity. That is to say that they are sized to ensure that the gravitational force exerted on the debris entrained in the primary flow 46 is larger than the upward drag force exerted on the debris by the flow 46 itself. This ensures that debris which enters the trap will settle to the bottom of the trap.
- the settling chamber is the portion of the debris trap upstream of the vent holes.
- the debris trap 10 of the present invention Besides capturing radioactive debris other key design requirements for the debris trap 10 of the present invention are as follows. Firstly it must stay securely in place during operation. In addition, it must not have any parts that can become loose within the PHT system. It is also essential that the debris trap 10 fit through the manway in the primary head of a steam generator for easy installation.
- the inventive debris trap 10 must also be light, preferable less than 20 lb (9 kg) and hence easy for one person to install. Furthermore, it must be easy to enclose in a dust tight radioactively shielded envelope to allow handling and removal for safe storage. It must also be easy to remove and easy to transport to the storage site for radioactive waste after the radioactive debris has been captured. Finally it must be small enough so it does not significantly increase the primary heat transport system flow losses.
- the inventive radioactive debris trap 10 is suitable for installation in any steam generator and is capable of removing radioactive debris that may be present in any nuclear power plant PHT system.
- the radioactive debris trap 10 could be installed during a typical boiler outage, while the head is open and PHT system is already in a low-level drain state.
- the outlet side is chosen not only because it is less turbulent than the inlet, but also because the flow from a few select tubes that contain a higher than average concentration of debris particles may be targeted to be "partially filtered" without disrupting all of the primary flow.
- the key advantage of installing a debris trap inside the boiler is that the device has a very high probability of capturing most of the particles over the period of one reactor operating cycle of say 8000 hours. It is expected that the debris will be more concentrated in areas of direct primary inlet flow impingement, including tube ends near the center of the steam generator and near the divider plate 50. By locating the debris trap below the outlet ends of such tubes it is expected that the flow entering the debris trap will contain a relatively concentrated stream of debris which is available for capture within the debris trap.
- an approximate efficiency analysis may be performed using as an example, a power plant having eight steam generators per reactor.
- Each steam generator has 4200 tubes for a total of 33,600 tubes in all the steam generators.
- the radioactive debris trap 10 of the present invention is installed in two steam generators, (one steam generator in each group of steam generators supplied by the same pumps), it is expected that over time most of the debris will be removed.
- the debris trap will filter a small fraction of the fluid coming from the ends of the tubes directly above the debris trap.
- Table 1 shows the expected particle removal rate based on the assumption that debris is uniformly distributed within the primary fluid.
- a Computational Fluid Dynamic (CFD) analysis that includes particle tracking throughout the system will be used to more accurately predict the distribution of particles in the boiler tubes and in the debris trap as a function of time.
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- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- High Energy & Nuclear Physics (AREA)
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Plasma & Fusion (AREA)
- Thermal Sciences (AREA)
- Mechanical Engineering (AREA)
- Structure Of Emergency Protection For Nuclear Reactors (AREA)
- Monitoring And Testing Of Nuclear Reactors (AREA)
Abstract
Description
Claims
Priority Applications (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP09850772.6A EP2494558B1 (en) | 2009-10-30 | 2009-10-30 | Radioactive debris trap |
KR1020127013878A KR101658809B1 (en) | 2009-10-30 | 2009-10-30 | Radioactive debris trap |
JP2012535944A JP5490910B2 (en) | 2009-10-30 | 2009-10-30 | Radioactive debris trap |
CA2779336A CA2779336C (en) | 2009-10-30 | 2009-10-30 | Radioactive debris trap |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US12/609,026 | 2009-10-30 | ||
US12/609,026 US8457271B2 (en) | 2009-10-30 | 2009-10-30 | Radioactive debris trap |
Publications (1)
Publication Number | Publication Date |
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WO2011051751A1 true WO2011051751A1 (en) | 2011-05-05 |
Family
ID=43921409
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/IB2009/007544 WO2011051751A1 (en) | 2009-10-30 | 2009-10-30 | Radioactive debris trap |
Country Status (6)
Country | Link |
---|---|
US (2) | US8457271B2 (en) |
EP (1) | EP2494558B1 (en) |
JP (1) | JP5490910B2 (en) |
KR (1) | KR101658809B1 (en) |
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WO (1) | WO2011051751A1 (en) |
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US9523496B2 (en) | 2012-01-17 | 2016-12-20 | Bwxt Nuclear Energy, Inc. | Integral pressurized water reactor with external steam drum |
CN207038182U (en) * | 2017-03-29 | 2018-02-23 | 泰拉能源有限责任公司 | Caesium collector |
JP6815923B2 (en) * | 2017-04-17 | 2021-01-20 | 日立Geニュークリア・エナジー株式会社 | Radioactive particle removal system in liquid and method for removing radioactive fine particles in liquid |
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2009
- 2009-10-30 US US12/609,026 patent/US8457271B2/en active Active
- 2009-10-30 CA CA2779336A patent/CA2779336C/en active Active
- 2009-10-30 JP JP2012535944A patent/JP5490910B2/en active Active
- 2009-10-30 KR KR1020127013878A patent/KR101658809B1/en active IP Right Grant
- 2009-10-30 WO PCT/IB2009/007544 patent/WO2011051751A1/en active Application Filing
- 2009-10-30 EP EP09850772.6A patent/EP2494558B1/en not_active Not-in-force
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2013
- 2013-04-26 US US13/871,506 patent/US8619942B2/en active Active
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JPS61122402A (en) | 1984-11-15 | 1986-06-10 | ウエスチングハウス エレクトリック コ−ポレ−ション | Steam generator |
US7037436B2 (en) * | 2001-12-31 | 2006-05-02 | Clark Joseph Use | Method of cleaning water pollution trap |
US6890443B2 (en) * | 2003-04-29 | 2005-05-10 | Amphion International Limited | Spin filter system |
CA2568936A1 (en) | 2005-11-30 | 2007-05-30 | Xerox Corporation | Phase change inks |
US20080185325A1 (en) * | 2007-02-01 | 2008-08-07 | Imbrium Systems Inc. | Pollutant Trap |
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See also references of EP2494558A4 |
Also Published As
Publication number | Publication date |
---|---|
EP2494558B1 (en) | 2017-04-19 |
JP2013509577A (en) | 2013-03-14 |
US8457271B2 (en) | 2013-06-04 |
US8619942B2 (en) | 2013-12-31 |
JP5490910B2 (en) | 2014-05-14 |
CA2779336C (en) | 2016-02-16 |
EP2494558A4 (en) | 2014-06-11 |
EP2494558A1 (en) | 2012-09-05 |
CA2779336A1 (en) | 2011-05-05 |
US20130259185A1 (en) | 2013-10-03 |
KR101658809B1 (en) | 2016-09-22 |
KR20120102666A (en) | 2012-09-18 |
US20110103538A1 (en) | 2011-05-05 |
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