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Page 1 of 14 DSAR-9.5 Auxiliary System Spent Fuel Handling System Rev 2 Safety Classification: Usage Level:
Safety Information Change No.: EC 69625 Reason for Change: This section is being updated with the results of the Design and Licensing Basis Reconstitution project.
Preparer: J. Spilker & J. Bostelman Fort Calhoun Station
DSAR 9.5 Information Use Page 2 of 14 Spent Fuel Handling System Rev. 2 Table of Contents 9.5 Spent Fuel Handling System ........................................................................................... 4 9.5.1 Design Bases........................................................................................................ 4 9.5.1.1 General .................................................................................................. 4 9.5.1.2 Prevention of Criticality during Transfer and Storage ............................. 4 9.5.1.3 Fuel Storage Radiation Shielding........................................................... 5 9.5.1.4 Radioactivity Release............................................................................. 6 9.5.1.5 Deleted................................................................................................... 6 9.5.1.6 Spent Fuel Storage Rack Seismic Design ............................................. 6 9.5.1.7 Deleted................................................................................................... 6 9.5.1.8 B.5.b Requirements ............................................................................... 6 9.5.2 System Description ............................................................................................... 6 9.5.3 System Components ............................................................................................ 7 9.5.3.1 Deleted................................................................................................... 7 9.5.3.2 Spent Fuel Storage Pool ........................................................................ 7 9.5.3.3 Deleted................................................................................................... 8 9.5.3.4 Major Handling Equipment ..................................................................... 8 9.5.4 System Operation ................................................................................................. 9 9.5.4.1 Deleted................................................................................................... 9 9.5.4.2 Deleted................................................................................................... 9 9.5.4.3 Deleted................................................................................................... 9 9.5.4.4 Deleted................................................................................................... 9 9.5.4.5 Deleted................................................................................................... 9 9.5.4.6 Deleted................................................................................................... 9 9.5.4.7 Deleted................................................................................................... 9 9.5.4.8 Spent Fuel Handling Machine .............................................................. 10 9.5.4.9 Deleted ................................................................................................ 10 9.5.4.10 Deleted................................................................................................. 10 9.5.4.11 Personnel Safety Features................................................................... 10 9.5.5 Design Evaluation ............................................................................................... 11 9.5.6 Availability and Reliability.................................................................................... 12 9.5.7 Tests and Inspections ......................................................................................... 12 9.5.8 Specific References ............................................................................................ 13 9.5.9 General References ............................................................................................ 14
DSAR 9.5 Information Use Page 3 of 14 Spent Fuel Handling System Rev. 2 List of Tables Table 9.5-1 -Spent Fuel Storage............................................................................................. 9
DSAR 9.5 Information Use Page 4 of 14 Spent Fuel Handling System Rev. 2 9.5 Spent Fuel Handling System 9.5.1 Design Bases 9.5.1.1 General The spent fuel handling system provides for the storage and safe handling of fuel under all foreseeable conditions including transfer to casks for storage or shipment of irradiated fuel following radioactive decay. The design and construction of the system includes interlocks, travel and load limiting devices and other protective measures to minimize the possibility of mishandling or equipment malfunction that could damage the fuel and cause fission product release. Power operation of the system components is supplemented by manual backup to insure that the transfer of a fuel assembly can be completed in the event of a power failure.
9.5.1.2 Prevention of Criticality during Transfer and Storage Spent fuel assemblies are stored in stainless steel racks consisting of vertical cells grouped in parallel rows with a center-to-center distance in Region 1 of 9.821" (E-W) x 10.363" (N-S) and 8.652" in both directions in Region 2. Both types of racks contain the neutron poison material BoralTM. The BoralTM is attached as panels between each storage cell. The panels are protected with a stainless steel sheath. The racks are of rugged design to provide protection against mechanical damage to the fuel and the spacing is such that it is impossible to insert assemblies in other than the prescribed locations and to store more than a safe quantity of fuel. Borated water surrounds the spent fuel storage racks. The center-to-center distance of the storage racks is such that a keff of less than 0.95 is maintained even in the event that the boron concentration is reduced to 500 ppm under accident conditions (Ref 9.5-6). Keff is maintained less than 0.95 including uncertainties, under normal conditions with 0 ppm soluble boron (Ref 9.5-6).
DSAR 9.5 Information Use Page 5 of 14 Spent Fuel Handling System Rev. 2 The spent fuel storage racks consist of two distinct regions.
Region 1 can accept irradiated fuel. Region 2, however, can accept only spent fuel meeting the minimum exposure requirements currently specified in Figure 2-10 of the Technical Specifications or if a full length CEA is inserted into the fuel assembly and mechanically coupled. The criticality analysis with CEA insertion assumed full CEA insertion during their residence in the core. This is conservative since the CEAs had only limited insertion during their exposure in the core. Even with full length insertion in the core it was still shown that the amount of B10 remaining in the CEA was adequate to prevent exceeding the NRC criteria. A clip is attached to tie the CEA and fuel assembly together. The clip was designed such that it would not be able to be removed by the grapple on the fuel handling machine under normal handling conditions (References 9.5-4, 9.5-6, 9.5-8, &
9.5.9.1).
Fuel can be moved directly from Region 1 to Region 2 of the spent fuel pool after both a review and an independent verification of burnup adequacy have been performed. The fuel burnup determination is performed by surveillance test prior to fuel movement into Region 2.
Fort Calhoun Station complies with all of 10 CFR 50.68(b),
Criticality Accident Requirements (References 9.5-12 and 9.5-13).
9.5.1.3 Fuel Storage Radiation Shielding Adequate shielding for radiation protection of personnel is provided by the handling of irradiated fuel under not less than 10 feet of water. Mechanical stops are provided on all handling equipment which limit the height of withdrawal of the irradiated fuel to maintain the low level of radiation required for unrestricted occupancy of the area by personnel. The system is designed such that water cannot drain by gravity out of the fuel storage pool below the level of the top of the stored fuel in its storage rack (see Section 9.5.3.2).
DSAR 9.5 Information Use Page 6 of 14 Spent Fuel Handling System Rev. 2 9.5.1.4 Radioactivity Release The accidental release of radioactivity from irradiated fuel to the atmosphere is addressed in the fuel handling accident analysis in DSAR Section 14.18.
9.5.1.5 Deleted 9.5.1.6 Spent Fuel Storage Rack Seismic Design The spent fuel rack is a seismic category I structure (Specific Reference 9.5-11). The design of the fuel racks is in compliance with the requirements of USNRC "OT Position Paper for Review and Acceptance of Spent Fuel Storage and Handling Applications",Section IV, and Standard Review Plan (SRP)
(References 9.5-4 & 9.5-19). The rack is a free-standing structure consisting of discrete storage cells which are loaded with free-standing fuel assemblies. Detailed seismic design information and analyses for the SFP racks is contained in Reference 9.5-11.
9.5.1.7 Deleted 9.5.1.8 B.5.b Requirements Section B.5.b of the February 25, 2002, Interim Compensatory Measures Order (EA02-026) pertains to a beyond design basis event. This license condition, now as a part of the renewed facility license, requires mitigation strategy including spent fuel pool mitigation measures..
9.5.2 System Description Fuel movement is accomplished by handling irradiated fuel assemblies underwater at all times. The use of borated water provides a transparent radiation shield, a cooling medium, and a neutron absorber to prevent inadvertent criticality.
The storage pool was originally designed to accommodate 178 fuel assemblies (1-1/3 cores) and the spent fuel shipping cask. The capacity of the spent fuel storage pool was subsequently increased to 483 fuel assemblies (3-2/3 cores). In 1983, the spent fuel pool storage capacity was increased to 729 fuel assemblies (5-1/2 cores). In 1994, the spent fuel pool storage capacity was increased to 1083 fuel assemblies (8 cores). Spent CEAs are stored in the spent fuel assemblies.
DSAR 9.5 Information Use Page 7 of 14 Spent Fuel Handling System Rev. 2 The spent fuel handling machine is designed to move spent fuel assemblies to storage racks within the Spent Fuel pool and to remove the fuel from the storage rack and deposit it in a dry fuel storage cask for storage or off-site shipment. Fuel in the spent fuel pool is stored in a vertical position.
During all handling operations, a sufficient water shield is maintained over the top of the fuel assembly to restrict radiation exposures to operating personnel. The concentration of boron in the water is checked periodically to ensure adequate criticality margins. A minimum concentration of 500 ppm boron must be maintained in the spent fuel pool to prevent criticality during accident conditions (abnormal location of a fuel assembly; Reference 9.5-6).
9.5.3 System Components 9.5.3.1 Deleted 9.5.3.2 Spent Fuel Storage Pool The spent fuel storage pool is located outside the containment at the west side of the auxiliary building. The pool was designed for the underwater storage of spent fuel assemblies and CEAs after their removal from the core. Decay heat is removed by the cooling system described in DSAR Section 9.6. The pool was constructed of reinforced concrete and the entire wetted surface is lined with stainless steel plate. It was designed to support all dead and live loads including hydrostatic loads, and the effects of tornadoes and the maximum credible earthquake. Drainage grooves are provided behind the stainless steel liner to permit detection of any liner leakage.
Thermal and structural evaluation of the walls and floor of the spent fuel pool was performed to determine the effects of gamma radiation heating on the pool floor, walls and liner plates (References 9.5-2, 9.5-3, and 9.5-7). The analysis consisted of the calculation of the energy deposition rate from gamma radiation in the concrete walls and floor of the spent fuel pool. These rates were subsequently used in thermal and structural calculations to determine the bounding temperature rise in the concrete walls and floor from the gamma radiation.
It was determined that the acceptance criterion of 133.2°F mean temperature and 58.9°F temperature gradient for the walls cannot be satisfied if recently discharged fuel assemblies are placed directly adjacent to the walls. At least one row of the peripheral cells must contain fuel assemblies that have cooled a minimum of one year in order to satisfy the acceptance criteria. The acceptance criterion of 678.5°F mean temperature and 187.5°F temperature gradient for the floor slab is satisfied.
DSAR 9.5 Information Use Page 8 of 14 Spent Fuel Handling System Rev. 2 Design of the pool and its cooling system and connections to the pool are such that the pool cannot be drained below the level of the top of the stored fuel when in its storage rack. The top of a fuel assembly in a storage rack is about the same elevation as the bottom of the gate connecting the pool with the fuel transfer canal which is at elevation 1008'-6". A plate has been installed across the bottom of the gate opening to raise the minimum possible water level in the pool to 1009'-8.5".
There are no pipes in the pool below this elevation. The water inlet line enters the pool at elevation 1034'-0" and terminates at elevation 1031'-7". The drain line enters the pool and terminates at elevation 1011'-4". When AC-187 located just outside the pool wall on the lower suction line is closed, the pool is protected from any ruptures of the line beyond the valve. The line is designed such that a rupture between the valve and the pool wall could not drain the pool below elevation 1011'-0".
Spent fuel assemblies are handled by underwater tools which are operated from a platform on the spent fuel handling machine. The tools are attached to the hoist by a safety latch and are stored in fixtures on the pool wall when not in use.
9.5.3.3 Deleted 9.5.3.4 Major Handling Equipment The handling equipment includes the spent fuel handling machine and the associated controls and communication equipment.
Details of the construction, design and function of this equipment are presented in Section 9.5.4.
DSAR 9.5 Information Use Page 9 of 14 Spent Fuel Handling System Rev. 2 Table 9.5-1 -Spent Fuel Storage Spent Fuel Storage Pool Core Storage Capacity Region 1 - 1.2 Cores Region 2 - 6.9 Cores Equivalent No. of Fuel Assemblies 1083 Number of Space Accommodations for Spent Fuel Shipping Casks 1 Center-to-Center Spacing for Assemblies, inches Region 1 - 10.363" x 9.821" Region 2 - 8.652" Maximum Keff Without Borated Water Reference 9.5-6 Miscellaneous Details Wall Thickness of Spent Fuel Storage Pool, ft 2 to 5-1/2 Weight of Fuel Assembly, lb (rack design) 1380 Capacity of SIRW Tank, gal at 180 (Ref. 9.5-5)313,800 Spent Fuel Storage Pool Gross Volume, gal 215,000 The spent fuel pool water volume available with all Spent fuel racks full of assemblies (Ref. 9.5-1) 193,886 9.5.4 System Operation 9.5.4.1 Deleted 9.5.4.2 Deleted 9.5.4.3 Deleted 9.5.4.4 Deleted 9.5.4.5 Deleted 9.5.4.6 Deleted 9.5.4.7 Deleted
DSAR 9.5 Information Use Page 10 of 14 Spent Fuel Handling System Rev. 2 9.5.4.8 Spent Fuel Handling Machine The basic structure of the spent fuel handling machine is a traveling bridge which spans the spent fuel pit and moves on rails so as to provide area coverage for all spent fuel racks and the transfer canal. A trolley and fuel hoist are mounted on the bridge structure and travel horizontally at 90° to the bridge travel. The trolley is used to support miscellaneous tools associated with fuel repair, reconnaissance and inspection. The hoist hook supports the long tool used for grappling fuel assemblies. In operation, the hoist hook and tool are located over the fuel assembly by rectangular coordinate positioning of the bridge and trolley.
Grapple load indication and limits are provided to prevent unusual loads during removal and insertion operations. The rotation of fuel is manually controlled via the grapple tool. A portable handling tool is used to install, remove, and reposition Control Element Assemblies (CEAs). Manipulation of the CEAs is performed in the spent fuel pool, with the operator working from spent fuel handling machine FH-12. The same handling tool is also used for manipulation of flow plugs. Other portable handling tools are used to install, remove and reposition the poison rods and neutron sources. Manipulation with the other tools is performed in the spent fuel pool, with the operator working from spent fuel handling machine FH-12.
9.5.4.9 Deleted 9.5.4.10 Deleted 9.5.4.11 Personnel Safety Features Safety nets over the fuel transfer canal and the new fuel storage area (Room 25A) provide protection against personnel falling from the 1038'-6" level of the spent fuel deck.
DSAR 9.5 Information Use Page 11 of 14 Spent Fuel Handling System Rev. 2 9.5.5 Design Evaluation Underwater handling of spent fuel provides ease and safety in handling operations. Water is an effective, transparent radiation shield and an efficient cooling medium for removal of decay heat. Basic provisions to ensure the safety of spent fuel handling operations are:
- Gamma radiation levels in the fuel storage areas are continuously monitored (see DSAR Section 11.2.3 and Reference 9.5-12). These monitors provide an audible alarm at the initiating detector and in the control room, indicating an unsafe condition.
- To prevent fuel assemblies from swinging into the wall during fuel movement in the spent fuel pool, zone boundaries provide a means of enforcing low speeds around the perimeter of the pool as well as providing bridge and trolley lockouts to prevent collision with the walls of the pool. A Travel Override Switch allows travel beyond the lockouts to access the perimeter Fuel Rack locations.
- The design of the equipment places physical limits on the extent of fuel movement, thereby avoiding the possibility of raising fuel beyond a safe limit. Fuel storage rack spacing provides positive protection against criticality in the event of inadvertent flooding of the fuel storage area with unborated water. The design of the fuel storage pool is such that water cannot drain out of the pool by gravity below the level of the top of stored fuel (see Section 9.5.3.2).
- In the unlikely event that a spent fuel cask falls into the spent fuel pool, the stainless steel liner could be punctured; however, the 12-foot thick reinforced concrete mat below the spent fuel pool would not be penetrated and leakage of water from the spent fuel pool would be slow.
The spent fuel pool makeup system can provide 500 gpm and additional water is available from both the demineralized water system and the fire protection system using hoses.
DSAR 9.5 Information Use Page 12 of 14 Spent Fuel Handling System Rev. 2 9.5.6 Availability and Reliability FH-12 has automatic, semi-automatic and manual modes of operation. The control in auto and semi-auto modes is accomplished using a programmable logic controller or PLC. Full manual control is accomplished using handwheels which are provided to allow bridge, trolley and hoist motion in the event of a power loss.
Operability of the spent fuel handling system is assured by functional testing (to include a load test on the spent fuel handling crane that will be required to handle spent fuel assemblies), prior to commencing fuel movement operations.
The applicable fuel handling equipment is tested not more than 30 days prior to moving fuel and is retested thereafter whenever the equipment is idle for more than 30 days. Maintenance which effects interlocks and/or setpoints also requires that the equipment be retested prior to using it to move fuel.
9.5.7 Tests and Inspections The spent fuel handling equipment was partially assembled at the fabricator's facility and was tested for correctness of operation, after which it was shipped directly to the site where the complete system was installed and tested.
FH-12 was installed on rails at the fabricator's facility where various machine functions were tested. Functions tested include:
- Indexing the machine to simulated spent fuel pool locations;
- Verification of the hoist load weighing system;
- Bridge, Trolley and Hoist operation
- Verification of interlocks and boundary zones
- Automatic and semi-automatic control verification
DSAR 9.5 Information Use Page 13 of 14 Spent Fuel Handling System Rev. 2 9.5.8 Specific References 9.5-1 FC06765 R1, Spent Fuel Pool and Fuel Transfer Canal Tank Curves 9.5-2 FC07586, Revision 0, Maximum Gamma Energy Deposition Rates in Spent Fuel Storage Pool Walls and Floor with EPU Spent Fuel Assemblies 9.5-3 FC07587, Revision 0, Thermal Evaluation of Gamma Heating on SFP Walls in Support of EPU 9.5-4 LIC-92-340A Licensing Report for Spent Fuel Storage Capacity Expansion, FLC-92-005, 07/07/92 9.5-5 FC07376 R0, Safety Injection Refueling Water Storage Tank Fill Curve 9.5-6 EA96-001, Revision 1, Criticality Safety Evaluation of the Ft.
Calhoun Spent Fuel Storage Rack for Maximum Enrichment Capability 9.5-7 FC06013, Revision 1, Pool Structural Analysis Report for Ft.
Calhoun Nuclear Station Spent Fuel Pool, February 2005 9.5-8 EC 69042, CEA Locking Clips in order to meet Technical Specification 2.8.3(1) 9.5-9 Deleted 9.5-10 Unused 9.5-11 MR-FC-91-009, SFP Rerack (EC 11106) 9.5-12 LIC-06-0029, Commitment to Fuel Storage Area Radiation Monitoring 10 CFR 50.68(b), 03/17/06 9.5-13 10 CFR 50.68, Criticality Accident Requirements 9.5-14 Letter from OPPD (J. A. Reinhart) to NRC (Document Control Desk), Fort Calhoun Station, Unit No. 1, Response Providing Information Regarding Implementation Details for the Phase 2 and 3 Mitigation Strategies, dated February 16, 2007 (LIC-07-0007)
DSAR 9.5 Information Use Page 14 of 14 Spent Fuel Handling System Rev. 2 9.5-15 Letter from OPPD (H. J. Faulhaber) to NRC (Document Control Desk), Revised Fort Calhoun Station, Unit No. 1, Response Providing Information Regarding Implementation Details for the Phase 2 and 3 Mitigation Strategies, dated May 4, 2007 (LIC-07-0030) 9.5-16 Letter from NRC (M. T. Markley) to OPPD (R. T. Ridenoure), Fort Calhoun Station, Unit No. 1-Confirming License Amendment to Incorporate the Mitigation Strategies Required by Section B.5.b of Commission Order EA-02-026 (TAC No. MD4534), dated July 26, 2007 (NRC-07-0073) 9.5-17 Deleted 9.5-18 Deleted 9.5-19 NUREG-0800, (Formerly issued as NUREG-75/087) Standard Review Plan for the Review of Safety Analysis Reports for Nuclear Power Plants: LWR Edition 9.5-20 FC06000, Revision 0, Archival Report of Whole Pool Multi-Rack Analysis for Fort Calhoun Station 9.5-21 OPPD Engineering Analysis, EA17-006, Revision 0, DSAR-9.5, Auxiliary System - Spent Fuel Handling System 9.5.9 General References 9.5.9.1 NRC Safety Evaluation Report Related to Technical Specification Amendment 133, October 2, 1990 9.5.9.2 NRC Safety Evaluation Report Related to Technical Specification Amendment 13, July 2, 1976 9.5.9.3 NRC Safety Evaluation Report Related to Technical Specification Amendment 75, September 9, 1983 9.5.9.4 NRC IE Bulletin No. 78-08, Radiation Levels From Fuel Element Transfer Tubes, June 12, 1978 9.5.9.5 NRC Safety Evaluation Report Related to Technical Specification Amendment 174, July 30, 1996 9.5.9.6 NRC Safety Evaluation Report Related to Technical Specification Amendment No.155, (Spent Fuel Storage Racks) August 12, 1993 9.5.9.7 Supplement to NRC Safety Evaluation Report Related to Technical Specification Amendment No.155, (Spent Fuel Storage Racks) April 9, 1996