ML20170A419

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Independent Spent Fuel Storage Installation Updated Decommissioning Safety Analysis Report, DSAR-9.6, Rev. 2, Auxiliary Systems, Spent Fuel Pool Cooling System
ML20170A419
Person / Time
Site: Fort Calhoun, 07100256  Omaha Public Power District icon.png
Issue date: 04/30/2020
From:
Omaha Public Power District
To:
Office of Nuclear Reactor Regulation, Office of Nuclear Material Safety and Safeguards
Shared Package
ML20170A380 List: ... further results
References
LIC-20-0005
Download: ML20170A419 (9)
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Page 1 of 9 DSAR-9.6 Auxiliary Systems Spent Fuel Pool Cooling 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 Fort Calhoun Station

DSAR-9.6 Information Use Page 2 of 9 Spent Fuel Pool Cooling System Rev. 2 Table of Contents 9.6 Spent Fuel Pool Cooling System .................................................................................. 4 9.6.1 Design Bases.................................................................................................... 4 9.6.2 System Description ........................................................................................... 4 9.6.3 System Components ........................................................................................ 6 9.6.4 System Operation ............................................................................................. 7 9.6.5 Design Evaluation ............................................................................................. 8 9.6.6 Availability and Reliability ................................................................................. 8 9.6.7 Tests and Inspections ....................................................................................... 8 9.6.8 References ....................................................................................................... 9

DSAR-9.6 Information Use Page 3 of 9 Spent Fuel Pool Cooling System Rev. 2 List of Tables Table 9.6 Spent Fuel Cooling System, Design and Operating Data................................... 6

DSAR-9.6 Information Use Page 4 of 9 Spent Fuel Pool Cooling System Rev. 2 9.6 Spent Fuel Pool Cooling System 9.6.1 Design Bases The spent fuel pool cooling system was designed to remove decay heat from spent fuel assemblies stored in the pool and to control and maintain the chemistry and clarity of the pool water. It can remove decay heat from a full core discharged from the reactor 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> after shutdown at a rate of 3 assemblies/hour from a power level of 1500 MWt, while maintaining the pool water temperature below 140°F (a heat load of 20.7 x 106 Btu/hr).

(Reference 9.6.8.8) The pool has the capability to accommodate 1083 unconsolidated fuel assemblies. (Reference 9.6.8.1)

The spent fuel pool was designed for an operating plant. Decay heat will continue to reduce. This design bounds all defueled plant conditions.

The piping is so arranged that failure of any pipeline connected to the pool will not drain the pool below the top of the stored fuel when in its storage rack.

The spent fuel pool cooling system was designed and constructed to Seismic Class I standards (see Appendix F).

Alternate spent fuel pool (SFP) cooling uses portions of the previously used shutdown cooling system and safety injection system to provide an alternate backup for the spent fuel pool cooling system in case of failure. The piping in this portion of the system is sized such that it matches the flow rates that will be seen with the primary installed system. Additionally, it is cooled by the same Component Cooling Water. Therefore heat removal performance with the alternate system would be similar to the spent fuel pool cooling system.

Under prolonged loss of the fuel pool cooling system, the pool water temperature could reach 210°F (i.e. boiling). Under these conditions, the ultimate strength capacity allowables are not exceeded (Ref. 9.6.8.10). As boiling of the pool will cause a loss of inventory, there are multiple methods designed to provide makeup to the pool to ensure uncovery of fuel does not occur. These are available in the form of SIRWT makeup, demineralized water, fire protection water, and beyond design basis fill equipment.

9.6.2 System Description The spent fuel pool cooling system is shown in P&ID 11405-M-11. The system consists of two storage pool circulation pumps, a storage pool heat exchanger, a demineralizer and filter, two fuel transfer canal drain pumps, piping, valves and instrumentation.

DSAR-9.6 Information Use Page 5 of 9 Spent Fuel Pool Cooling System Rev. 2 The storage pool pumps circulate borated water through the storage pool heat exchanger and return it to the pool. Cooling water to the heat exchanger is provided by the component cooling water system (see Section 9.7). The purity and clarity is maintained by diverting a portion of the circulated water through the demineralizer and the filter. The fuel transfer canal drain pumps are utilized to:

  • Provide pool make-up water from the safety injection and refueling water tank (SIRWT);
  • Drain the fuel transfer canal and return the water to the SIRWT or the radioactive waste disposal system (RWDS).

Since the plant is shutdown, and the core is fully off loaded, the shutdown cooling system, low pressure safety injection (LPSI) pumps and the shutdown cooling heat exchangers provide a backup for the spent fuel pool cooling system in case of failure of that system. The shutdown cooling heat exchanger is cooled by the same CCW as the spent fuel pool heat exchanger, or in a loss of CCW, RW cooling can be supplied directly.

This backup cooling capability of the shutdown cooling system is not available when the CCW or RW systems are out of service for maintenance.

This condition is acceptable due to the short duration of the system outages, close attention to the fuel pool heatup rate, and the availability of makeup water sources.

DSAR-9.6 Information Use Page 6 of 9 Spent Fuel Pool Cooling System Rev. 2 9.6.3 System Components The design and operating data for the spent fuel pool cooling system components are shown in Table 9.6-1:

Table 9.6-1 Spent Fuel Cooling System, Design and Operating Data (Archive information)

Storage Pool Circulation Pumps, Item No's AC-5A and AC-5B Number Installed 2 Type Horizontal, Centrifugal Capacity, gpm/pump 900 TDH, ft 120 Nominal Operating Temperature, °F 110 Material of Construction Austenitic Stainless Steel Motor Enclosure Drip Proof Storage Pool Heat Exchanger, Item No. AC-8 Number Installed 1 Type Shell and U-Tube Code ASME Section III, Class C, 1968 and TEMA Class R Capacity, Btu/hr 9 x 106 to 20.7 x 106*

Materials of Construction Shell Side Carbon Steel Tube Side Type 304 SS

  • Heat removal capacity varies with pool circulating water temperature conditions. The AC-8 has been rerated as a result of the 1994 spent fuel pool rerack project thermal hydraulic analysis (Reference 9.6.8.1).

Demineralizer, Item No. AC-7 Number Installed 1 Type Mixed Bed, Non-Regenerative Code ASME Section III, Class C, 1968 Flow Rate, gpm 75 to 300 Material of Construction Austenitic SS

DSAR-9.6 Information Use Page 7 of 9 Spent Fuel Pool Cooling System Rev. 2 Table 9.6-1 (Continued)

Filter, Item No. AC-6 Number Installed 1 Type Vertical Cylinder, Non-Back-flushable Code ASME Section III, Class C, 1968 Flow Rate, gpm 75 to 300 Retention of 200 Micron Particles, % 95 Material of Construction Austenitic SS Fuel Transfer Canal Drain Pumps, Item No's AC-13A and AC-13B Number Installed 2 Type Horizontal, Centrifugal Capacity, gpm/pump 250 TDH, ft 100 Nominal Operating Temperature, °F 110 Material of Construction Austenitic SS Motor Enclosure Drip-Proof Spent Fuel Pool Strainer, Item No. AC-14 Number Installed 1 Size, inch 8 Material of Construction Austenitic SS Piping Code USAS B31.7 1968, Class III and B31.1 1967 Material ASTM A312, Type 304 SS 9.6.4 System Operation All system functions are locally controlled. The equipment and instruments are accessible during normal operation. An analysis of fluid samples provides the operator with data for selection and adjustment of flow through the demineralizer-filter circuit. Temperature regulation is accomplished by adjustment of the component cooling water flow to the storage pool heat exchanger. All pumps are started locally.

DSAR-9.6 Information Use Page 8 of 9 Spent Fuel Pool Cooling System Rev. 2 9.6.5 Design Evaluation The gross volume of the spent fuel pool is approximately 215,000 gallons.

The spent fuel pool volume available with all spent fuel racks full of assemblies is approximately 193,886 gallons. The system is designed to cool the pool water by recirculating the contents through the cooling loop once every two hours with both pumps operating. The demineralizer-filter circuit can, under normal operating conditions, process one half of the pool contents in 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. To preclude carry-over of resin into the spent fuel pool, the filter is installed downstream of the demineralizer. The demineralizer and the filter can be isolated individually for maintenance purposes, without interruption of the normal cooling operation. To accommodate water purification during fuel movement periods, the demineralizer and filter have an operating capacity four times as high as the normal requirements. This assures the system's capability to maintain the desired purity and clarity of the pool water.

Make-up to the spent fuel pool, to compensate for evaporation losses, for example, is normally from the SIRWT. Demineralized water can be used for makeup. If necessary, pool water can be pumped to the radioactive waste processing system for disposal.

9.6.6 Availability and Reliability All the equipment in the system is manually operated; there are no pneumatically or electrically actuated valves. Metals in contact with borated water are austenitic stainless steel.

With a freshly unloaded full core in the pool assumed to be discharged from the reactor 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> after shutdown and upon failure of the spent fuel pool cooling system at the peak temperature instant, the pool temperature (135°F) would rise to the boiling point of 210°F within 7.0 hours0 days <br />0 hours <br />0 weeks <br />0 months <br />. This scenario conservatively assumes the spent fuel pool has 1339 spent fuel assemblies with consolidation. The spent fuel pool contains the maximum number of assemblies it will contain in the current state. This is a total of 944 fuel assemblies. The boiling point of 210°F is due to the FCS barometric pressure based for the 1000 ft. elevation. (Reference 9.6.8.8)

The spent fuel pool was designed for an operating plant. Decay heat will continue to reduce. This design bounds all defueled plant conditions.

9.6.7 Tests and Inspections All equipment in the system was cleaned and tested prior to installation in accordance with the applicable codes. The system was also cleaned and hydrostatically tested after installation. Welds were inspected as required by the code and all other connections checked for tightness.

DSAR-9.6 Information Use Page 9 of 9 Spent Fuel Pool Cooling System Rev. 2 Prior to fuel loading the system was tested with regard to flow paths, flow capacity, heat transfer capability, mechanical operability and purification efficiency. Pressure, temperature, flow and level indicating instruments were calibrated and checked for operability.

The equipment is accessible for inspection and maintenance at all times.

9.6.8 References 9.6.8.1 MR-FC-91-009, Spent Fuel Pool Rerack 9.6.8.2 NRC Safety Evaluation Report Supporting Amendment Number 13, July 2, 1976 9.6.8.3 NRC Safety Evaluation Report Related to the Modification of the Spent Fuel Pool, September 9, 1983 9.6.8.4 NRC Safety Evaluation Report Related to Ultrasonic Fuel Inspection in the Spent Fuel Pool, March 12, 1987 9.6.8.5 IE Bulletin Number 78-08, Radiation Levels From Fuel Element Transfer Tubes, June 12, 1978 9.6.8.6 Engineering Analysis EA-FC-92-077, Licensing Report for Spent Fuel Pool Storage Expansion 9.6.8.7 MF987, Society of Manufacturing Engineers, Rating Disposable Filters, September 1987 9.6.8.8 FC05988, Revision 4, Thermal-Hydraulic Analysis of Fort Calhoun Station Spent Fuel Pool with Maximum Density Storage 9.6.8.9 Regulatory Guide 1.13 Spent Fuel Storage Facility Design Basis Revision 1 9.6.8.10 FC06013, Revision 2, Pool Structural Analysis for the FC Nuclear Station Spent Fuel Pool 9.6.8.11 NRC Safety Evaluation Report Related to Technical Specification Amendment No.155, (Spent Fuel Storage Racks) August 12, 1993 (NRC-93-0292) 9.6.8.12 Supplement to NRC Safety Evaluation Report Related to Technical Specification Amendment No.155, (Spent Fuel Storage Racks) April 9, 1996 (NRC-96-0062) 9.6.8.13 OPPD Engineering Analysis, EA17-007, Revision 0, DSAR-9.6, Auxiliary Systems - Spent Fuel Pool Cooling System

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