Earthquake-resistant fuel storage rack system for fuel pools in nuclear plants

Patent metadata

Field	Value
Publication number	US-10847274-B2
Application number	US-201715618774-A
Country	US
Kind code	B2
Filing date	Jun 9, 2017
Priority date	Feb 24, 2017
Publication date	Nov 24, 2020
Grant date	Nov 24, 2020

Abstract

A seismic-resistant fuel storage system for a nuclear fuel pool includes a lined fuel pool and a fuel rack comprising tubular nuclear fuel storage cells attached to a common baseplate. Pedestals protrude downwardly from the baseplate supporting the rack on the pool base slab. Spaced embedment plates are fixedly anchored to the base slab to eliminate relative movement between the plates and pool liner. The embedment plates comprise upwardly open recessed receptacles each entrapping one of the rack pedestals therein. The receptacles are configured such that lateral movement of the fuel rack along the base slab in the event of a seismic event is constrained via engagement between receptacle walls and pedestals. Lateral seismic loads are not transferred to the pool liner. In some embodiments, the baseplates in the pool are coplanar and may be abutting engaged to mitigate rack movement during a seismic event.

First claim

What is claimed is:

1. A seismic-resistant nuclear fuel storage system comprising:
a fuel pool comprising a base slab and plurality of vertical sidewalls collectively defining a cavity configured for wet storage of nuclear fuel;
a fuel rack comprising a plurality of vertically elongated tubular cells each defining a prismatic cavity configured for storing nuclear fuel therein, the cells attached to a common baseplate;
a plurality of pedestals attached to and protruding downwardly from the baseplate;
a plurality of spaced apart embedment plates fixedly anchored to the base slab, each embedment plate comprising an upwardly open receptacle having receptacle walls defining a receptacle depth, each receptacle receiving and entrapping one of the pedestals therein;
wherein the embedment plate receptacles are configured such that lateral movement of the fuel rack along the base slab in the event of a seismic event is constrained by engagement between the receptacle walls of each receptacle and the pedestals.

2. The fuel storage system according to claim 1 , wherein the pedestals elevate the baseplate of the fuel rack above the base slab creating a bottom plenum to allow pool water to circulate beneath the fuel rack for cooling the nuclear fuel.

3. The fuel storage system according to claim 1 , wherein the cells are formed by a plurality of upwardly open storage tubes fixedly attached to the baseplate and collectively defining lateral sides of the fuel rack.

4. The fuel storage system according to claim 3 , wherein the baseplate protrudes horizontally outwards beyond the lateral sides of the fuel rack creating a protruding peripheral ledge that extends around a perimeter of the fuel rack.

5. The fuel storage system according to claim 1 , wherein the receptacle depth is 1 to 2 inches deep.

6. The fuel storage system according to claim 1 , wherein the receptacle is positioned in a central region of the embedment plate and surrounded by a flat top wall of the embedment plate.

7. The fuel storage system according to claim 1 , wherein the embedment plate includes an upwardly open second receptacle spaced apart from the receptacle for receiving and entrapping a pedestal from a second fuel rack.

8. The fuel storage system according to claim 1 , wherein a horizontal gap formed between the receptacle walls and lateral sides of the pedestal is less than ¼ of a maximum transverse cross sectional dimension of the pedestal.

9. The fuel storage system according to claim 1 , further comprising a pool liner disposed on the base slab of the fuel pool beneath the fuel rack, the pool liner extending between the plurality of spaced apart embedment plates and having a thickness less than the embedment plate, wherein there is no relative movement between embedment plates and the pool liner in the event of a seismic event.

10. The fuel storage system according to claim 9 , wherein the embedment plates are each hermetically seal welded around their perimeters to the pool liner at all lateral sides to form an impervious barrier to outward leakage of pool water from the fuel pool.

11. The fuel storage system according to claim 10 , wherein the embedment plates protrude upwards beyond a top surface of adjacent portions of the pool liner around each embedment plate.

12. The fuel storage system according to claim 10 , wherein the embedment plates are embedded directly into the base slab of the fuel pool such that there is no pool liner interposed between the embedment plates and the base slab.

13. The fuel storage system according to claim 10 , wherein the embedment plates are each disposed on top of the pool liner and anchored to the base slab of the fuel pool by one or more through anchors extending from each embedment plate through the pool liner into the base slab.

14. A fuel rack stabilization system for seismic-resistant storage of nuclear fuel, the system comprising:
a fuel pool comprising a base slab and plurality of vertical sidewalls collectively defining a cavity configured for submerged wet storage of nuclear fuel;
a plurality of fuel racks supported on the base slab, each fuel rack comprising a plurality of vertically elongated tubes each defining a prismatic cavity configured for storing nuclear fuel therein, the tubes attached to a common baseplate;
each fuel rack comprising a plurality of spaced apart pedestals protruding downwardly from the baseplate;
a plurality of spaced apart embedment plates fixedly anchored to the base slab, each embedment plate comprising at least one upwardly open embedment cavity having cavity walls, the cavities each receiving and entrapping a respective one of the pedestals of the fuel racks therein;
a pool liner secured to the base slab of the fuel pool, the pool liner extending between the plurality of spaced apart embedment plates and having a thickness measured between top and bottom surfaces of the pool liner less than a thickness of the embedment plate measured between top and bottom surfaces of the embedment plate outside of the embedment cavity;
wherein a perimeter of the embedment plates is hermetically seal welded to the pool liner around all lateral sides of the embedment plates to form an impervious barrier to outward leakage of pool water from the fuel pool;
wherein the embedment plate cavities are configured such that lateral movement of the fuel rack along the base slab caused by a seismic event is restricted by engagement between the cavity walls of each cavity and the pedestal such that laterally acting seismic forces are not transmitted to the pool liner.

15. The fuel rack stabilization system according to claim 14 , wherein the baseplates of the fuel racks are arranged substantially coplanar with each other and protrude laterally beyond vertical sidewalls of the tubes of each fuel rack to form horizontal protruding ledges around a perimeter of the fuel racks on all sides.

16. The fuel rack stabilization system according to claim 15 , wherein peripheral edges of mating horizontal protruding ledges between adjoining fuel racks in the fuel pool are in mutual abutting engagement.

17. The fuel rack stabilization system according to claim 16 , wherein the peripheral edges of the mating horizontal protruding ledges are mutually engaged for a majority of a length of the peripheral edges.

18. The fuel rack stabilization system according to claim 14 , wherein the fuel racks are arranged so that mating baseplates between adjoining fuel racks are horizontally spaced apart no more than ¼ inch between peripheral edges of the mating baseplates.

19. The fuel rack stabilization system according to claim 14 , wherein the cavity walls are cylindrical or rectilinear in configuration.

Assignees

• Holtec International

Inventors

• Singh Krishna P

Classifications

• G21C19/07 Primary

  Storage racks; Storage pools · CPC title

• G21F5/08

  Shock-absorbers, e.g. impact buffers for containers · CPC title

• Y02E30/30

  Nuclear fission reactors · CPC title

• G21F5/012 Primary

  Fuel element racks in the containers · CPC title

• G21C3/06

  Casings; Jackets · CPC title