ML16014A376

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Response to a Second Request for Additional Information Regarding Amendment Applications 270 and 255 Proposed Changes to Specific Regulatory Guide Commitments
ML16014A376
Person / Time
Site: San Onofre  Southern California Edison icon.png
Issue date: 01/12/2016
From: Kay J
Southern California Edison Co
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
TAC L53073, TAC L53074
Download: ML16014A376 (15)
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Text

{{#Wiki_filter:'I" S0UTHEI*N CALIFORNIA U IU~'J'I\~Manager, Regulatory Affairs An EDISON INThqRNAgTONAL".' Cornpany 10 CFR 50.90 January 12, 2016 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555-0001

Subject:

Docket Nos. 50-361 and 50-362 Response to a Second Request for Additional Information Regarding Amendment Applications 270 and 255 SProposed Changes to Specific Regulatory Guide Commitments San Onofre Nuclear Generating Station, Units 2 and 3

References:

1) Letter from T. J. Palmisano (SCE) to the U. S. Nuclear Regulatory Commission (NRC) dated August 20, 2015;

Subject:

Docket Nos. 50-361 and 50-362, Amendment Applications 270 and 255, Proposed Changes to Specific Regulatory Guide Commitments, San Onofre Nuclear Generating Station, Units 2 and 3 (ADAMS Accession No. ML15236A018)

2) Letter from M. Vaaler (NRC) to T. J. Palmisano (SCE) dated December 22, 2015;

Subject:

San Onofre Nuclear Generating Station, Units 2 and 3-Second Request for Additional Information Regarding the License Amendment Request to Make Changes to Specific Regulatory Guide Commitments Related to the Implementation of "Cold and Dark" Status (CA NOS. L53073 and L53074) (ADAMS Accession No. ML15348A367)

Dear Sir or Madam:

By letter dated August 20, 2015 (Reference 1), Southern California Edison (SCE) submitted a License Amendment Request (LAR), consisting of Amendment Applications Nos. 270 and 255, to Facility Operating License Numbers NPF-1 0 and NPF-1 5 for San Onofre Nuclear Generating Station (SONGS) Units 2 and 3, respectively. The LAR proposed to revise the Updated Final Safety Analysis Report (UFSAR) to revise specific Regulatory Guide commitments. By letter dated December 22, 2015 (Reference 2), the NRC provided a Second Request for Additional Information (RAI) regarding Reference 1. The response to the Second RAI is 

       *contained in Enclosure 1 to this letter.

Additionally, several concerns with the details in Reference 1 were identified in a recent NRC inspection. These concerns have been addressed in a revision to Reference 1, Attachment A, Proposed Changes to Specific Regulatory Guide Commitments, Spent Fuel Pool 'Island' Description. The revised information is provided as Enclosure 2 to this letter. P. O. Box 128 *-{ San Glemente, CA 92672

Document Control Desk The additional information provided in the enclosures does not affect the conclusions of the No Significant Hazards Consideration or the Environmental Consideration provided in Reference 1. There are no new regulatory commitments in this letter or the Enclosures. If you have any questions or require any additional information, please contact me at (949) 368-7418. Sincerely,

Enclosures:

1. Response to NRC Second Request for Additional Information
2. Revision to Attachment A of Proposed Changes to Specific Regulatory Guide Commitments cc: M. L. Dapas, Regional Administrator, NRC Region IV M. G. Vaaler, NRC Project Manager, SONGS Units 2 & 3 S. Y. Hsu, California Department of Public Health, Radiologic Health Branch 2

ENCLOSURE 1 RESPONSE TO NRC SECOND REQUEST FOR ADDITIONAL INFORMATION SAN ONOFRE NUCLEAR GENERATING STATION, UNITS 2 AND 3

SECOND REQUEST FOR ADDITIONAL INFORMATION PROPOSED CHANGES TO SPECIFIC REGULATORY GUIDE COMMITMENTS SOUTHERN CALIFORNIA EDISON SAN ONOFRE NUCLEAR GENERATING STATION. UNITS 2 AND 3 DOCKET NOS. 50-361 AND 50-362 By letter dated August 20, 2015 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML15236A018), as supplemented by responses to an initial request for additional information provided by letter dated November 19, 2015 (ADAMS Accession No. ML15327A410), Southern California Edison (SCE) requested an amendment to the facility operating licenses for the San Onofre Nuclear Generating Station, Units 2 and 3 (SONGS). The proposed amendment would revise Appendix 3A of the Updated Final Safety Analysis Report (UFSAR) to more fully reflect the permanently shutdown status of SONGS. The revision would include a limited set of exceptions and clarifications to referenced Regulatory Guides to reflect the significantly reduced decay heat loads in the SONGS Units 2 and 3 spent fuel pools and to support corresponding design basis changes and modifications that will allow for implementation of the "cold and dark" strategy outlined in the SONGS Post-Shutdown Decommissioning Activities Report (PSDAR). The following additional information is necessary to complete the NRC staff's technical review: REQUESTS FOR ADDITIONAL INFORMATION

4. Design Feature Technical Specification for Drainage Prevention General Design Criterion (GDC) 61, "Fuel Storage and Handling and Radioactivity Control,"

of Appendix A, "General Design Criteria for Nuclear Power Plants," to Title 10 of the Code of Federal Regulations(10 CFR), Part 50, states in part that fuel storage facilities shall be designed to prevent a significant reduction in fuel storage coolant inventory under accident conditions. In addition to capabilities described in the SONGS UFSAR, this criterion has been incorporated in the SONGS Facility Operating License as Technical Specification (TS) 4.3.2, "Drainage," in Section 4, "Design Features," which states: The spent fuel storage pool is designed and shall be maintained to prevent inadvertent draining of the pool below Technical Specification 3.1.1 value (23 feet above the top of irradiated fuel assemblies seated in the storage racks). The requirements of 10 CFR 50.36(c)(4), "Design Features,"specify that the design features to be included in the TSs are those features of the facility such as materials of construction or geometric arrangements, which, if altered or modified, would have a significant effect on safety and are not included in other portions of the TSs. In Attachment 3 to the letter dated November 19, 2015, SCE provided a spent fuel pooi level correlation that indicated the centerline of the spent fuel pool cooling suction line was located at an elevation below the level specified in TS 4.3.2. Since the spent fuel pool cooling suction line could drain or siphon coolant from the spent fuel pool volume inside the fuel transfer and cask loading area gates, the level specified in TS 4.3.2 (23 feet above the top of irradiated fuel assemblies seated in the storage racks) does not conform with the geometric arrangement of drainage prevention features provided for spent fuel pool piping penetrations and attached piping. Accordingly, please propose a revision to TS 4.3.2 that conforms to the geometric arrangement of piping penetrations and siphon protection design features within the spent fuel pool, or explain how inadvertent drainage to the level specified in TS 4.3.2 through the spent fuel pool cooling system suction piping and the independent spent fuel pool cooling system suction line is not possible. sCE Response The existing spent fuel pool (SFP) suction line configuration has not changed since the original plant design, construction, operation and licensing. The Safety Evaluation Report related to the operation of San Onofre Nuclear Generation Station Units 2 and 3 (Reference 1) Section 9.1 3 states that the NRC has reviewed the design of the Spent Fuel Pool and found it acceptable. 

    "We have reviewed the design of the spent fuel cooling and cleanup system and conclude that it meets the requirements of... General Design Criteria 61 as related to fuel storage systems design with provisions for containment of radioactive materials and decay heat removal. We further conclude that the system design meets the guidelines of Regulatory Guides 1.13, "Spent Fuel Storage Design Basis" regarding...prevention of excessive fuel pool water loss."

The content of the Units 2 and 3 Design Features Technical Specifications were initially based on plant elevation (specifically referenced 60' 6"). During the licensing of high density racks (Amendment No. 87 for SONGS Unit 2 and No. 77 for SONGS Unit 3 / March 10 1989 - May 1, 1990) a decision was made to revise the limit to 23 feet above the spent fuel assemblies. That value corresponds to Standard and improved Technical Specification content and the initial SONGS Limiting Condition for Operation (LCO) value, which preserves the conditions to use generic decontamination factors when calculating dose consequences of a Fuel Handling Accident (FHA) addressed historically by Regulatory Guide 1.25 and currently by Regulatory Guide 1.183. The analysis that credits these decontamination factors is associated with fuel handling operations and thus is more appropriately tied to the LCO than the Design Feature. SCE recently surveyed peer decommissioning plants and the results further Suggest that the LCO limit of 23 feet (SONGS TS 3.1.1) applicable during fuel movement is used to protect this safety analysis input. After re-reviewing the cited requirements, related guidance, peer Technical Specification content and previous interactions with the NRC, SCE considers the existing configuration, TS content, and other characteristics to fully meet the fundamental functional requirements and the GDC. Among those characteristics are the following: 

 *The safety purposes of the LCO minimum level include decontamination of releases from a FHA, shielding and cooling under a variety of conditions.
 *While the current system is in operation, the suction line has to remain available. SONGS Units 2 and 3 UFSAR Section 9.1.3.3 "Safety Evaluation" notes that: "Inadvertent draining of the SEP, including siphoning, below approximately 23 feet above the stored fuel is prevented by design features (siphon breakers and check valves, etc.) and Administrative Controls." These include low pool level and high sump level alarms..
 *The suction line is a moderate (i.e., not high) energy line designed to Seismic Category I requirements and thus not postulated to fail as noted in the SONGS Units 2 and 3 UFSAR Appendix 3.6B.
 *Consistent with the classification of the spent fuel pool and liner, the existing suction line from the pool through the first isolation valve (MU 102) is classified as safety-related. The balance of the line is classified as Augmented Quality (III-AQ) which imposes most Appendix B criteria (design control, etc. as described in the SONGS Units 2 and 3 Q-List, 90034).

There are also administrative requirements to close valves or take other manual actions if required. , 

 *Finally, and perhaps most importantly, oversight of the SEP conditions (level, radiation levels, etc.) are the most safety significant focus of the SONGS staff. Thus, malfunction of the system will be promptly recognized and corrected.

In conclusion, the cited Technical Specification Design Feature is used in conjunction with an LCO which is applicable "during movement of fuel assemblies in the spent fuel pool." SCE will maintain appropriate design features, administrative controls, alarm values and alarm response protocols; therefore, the value in the Technical Specification Design Features 4.3.2, while quite conservative, does not need to be changed.

5. Makeup Water In its response to RAI-SBPB-01, SCE described that any liner leaks into the leak chase would be limited to approximately 50 gallons/minute, which is within the capacity of the identified makeup capability, and that such leaks could also be mitigated by shutting the leak chase drain valves if appropriate to do so.

For design basis events that could cause a minor liner leak, such as a fuel handling accident, estimate the time available to take mitigating actions prior to the spent fuel water level decreasing to the point shielding may be ineffective (e.g., 10 feet above the top of stored fuel). Based on the available time, provide justification that appropriate makeup can be delivered to the spent fuel pool with a high probability of success before shielding of the fuel becomes ineffective. SCE Response There are no design basis events that result in penetration of the liner. The subject of a FHA not leading to liner failure was addressed in the "licensing of the high density racks (License Amendment Request Licensing Report Section 4.6.4.3.2, Reference 2 and Safety Evaluation Technical Report Section 4.3, Reference 3) and it was demonstrated that the dropped fuel assembly would not adversely impact the SFP liner and the liner would not be perforated. The SEP design is such that the steel liner is in direct contact with the concrete floor or walls. The leak chases are embedded into the concrete. Nevertheless, SCE has calculated the time for a non-mechanistic liner penetration causing a 50 gpm leak not terminated by isolation of the leak chases to reach a level of 10 feet above the fuel assemblies. With both gates open (the current and most likely configuration); the leak would drain the pool to 10 feet in -70 hours. The installed makeup systems can be started promptly and, if unavailable, the multiple back-up Mitigation Strategies can be placed in-service in less than two hours which has been demonstrated using minimum on-site staffing.

6. Island Spent Fuel Pool Cooling System In its response to RAI-SBPB-O1, SCE described that the proposed independent spent fuel pool cooling system independently takes suction from the spent fuel transfer pool through a pipe that extends from the operating floor down to the same elevation as the existing spent fuel pool cooling suction line.

GDC 61 states in part that fuel storage facilities shall be designed with a residual heat removal capability having reliability and testability that reflects the importance to safety of decay heat and other residual heat removal. Since the proposed independent spent fuel pool cooling system would draw water vertically from the transfer canal, address the effect of the suction design and location on the reliability of spent fuel pool cooling compared to the existing cooling system. Specifically, explain whether available net positive suction head would be adequate to restore forced cooling following an extended loss of cooling with the resulting increase in spent fuel pool temperature and whether transfer gate closure would interfere with cooling for an extended period. Justify the adequacy of the proposed independent cooling system design relative to GDC 61 considering these potential limitations on cooling system reliability. SCE Response: The concern associated with suction design and location relative to restart of the pumps after an extended loss of cooling has been evaluated for reliability. It is likely that the SFP would never reach temperatures where pump restart is challenged (i.e. greater than 1900 F) however, SCE has not performed a formal and rigorously conservative analysis to determine the equilibrium temperature possible as the fuel continues to decay. Rather than relying on calculation outcomes alone, primary pump NPSH concerns have been addressed by establishing temperature limits for restart and by a procedure provision to add cold water via the makeup system before pump restart, if required. Throttling secondary flow is also considered for continued chiller operation. Temperature monitoring will also indicate approach to limits and allow for any necessary actions to maintain adequate suction conditions for the pumps and chillers. There are no current plans to install a transfer gate. Provisions will exist for conditions if a transfer gate is installed. In this case, a temporary suction line would be connected to flanged connections to move the suction to the main part of the spent fuel pool as part of the system design. References

1) NUREG-071 2, Safety Evaluation Report related to the operation of San Onofre Nuclear Generating Station, Units 2 and 3,dated February, 1981
2) Letter From F. R. Nandy, SCE to the Nuclear Regulatory Commission dated April 19, 1 989,

Subject:

Spent Fuel Pool Reracking Amendment Application Nos. 78 and 64 (PCN-287)

3) Letter from L. E. Kokajko, NRC to H. B. Ray, SCE dated May 1, 1990,

Subject:

Issuance of Amendment No. 87 to Facility Operating License No. NPF-1 0 and Amendment No. 77 to Facility Operating License No. NPF-15, San Onofre Nuclear Generating Station Unit N~s. 2 and 3 ENCLOSURE 2 REVISION TO ATTACHMENT A OF PROPOSED CHANGES TO SPECIFIC REGULATORY GUIDE COMMITMENTS SAN ONOFRE NUCLEAR GENERATING STATION, UNITS 2 AND 3

Attachment A Spent Fuel Pool 'Island' Description Back~Qround Due to the significant reduction in Spent Fuel Pool (SEP) heat load since final plant shutdown and the reduction in potential boundary dose consequences for the few remaining credible events, the SEP cooling functional requirements are reduced. Based on industry decommissioning experience, the use of independent non-plant systems for providing SFP cooling will reduce the potential for decommissioning activities to inadvertently damage installed plant SEP-related components which could result in a loss of SEP cooling or pool inventory. San Onofre Nuclear Generating Station (SONGS) Units 2 and 3 will design and install an independent SEP cooling and purification system. This SEP cooling and purification system is referred to as the SEP Island. To safely maintain SEP cooling, the SEP Island design includes features that support cooling function reliability including component redundancy, redundant power sources, and system cross-tie capabilities. Current SFPCS Each unit of the current Spent Fuel Pool Cooling System (SFPCS) consists of two loops, the Spent Fuel Pool (SEP) cooling loop and the purification loop. The SFPCS is normally controlled manually from the main control panel. Main Control Room alarms for high SEP temperature, high and low SEP level, low SEP pump discharge pressure and, high radiation S.in the SEP area, are provided to alert the operator to abnormal circumstances. A local alarm for low SEP level is also provided. The SFPCS consists of two 100% capacity SEP pumps and two 100% capacity SEP heat exchangers. The two SEP pumps are connected to a common suction header and a common return header. The SEP05 also includes appropriate valves, piping, and instrumentation. SEP water is circulated by the SEP pumps through the SEP heat exchangers where it is cooled. The heat is rejected to the Component Cooling Water (CCW) System, which, in turn, rejects heat to the Salt Water Cooling system and ultimately to the Pacific Ocean. Neither the CCW nor SWC systems are otherwise impacted by this modification. The SFPCS includes a purification loop that has been administratively removed from service and the resin removed. The Independent Spent Fuel Pool Cooling System (ISFPCS) will be installed, tested and provide run-in time prior to removing the current system from operation. Thus, the ISFPCS will be operating and the current Spent Euel Pool Cooling System will be maintained as a fully-functional back-up. SEP Island System Overview ISEPCS is shown in the attached schematic. The design will include one primary loop per SEP. Each primary loop includes two 100% capacity pumps with a common intake and discharge header and a single heat exchanger. Replacement heat exchangers are readily available. There will be one secondary loop per SEP with a common intake and discharge he ader. The secondary loop is a closed system that uses air cooled chillers to cool the secondary side water. Each secondary loop will consist of two 100% capacity pumps. Both

the primary and independent fromsecondary loop the current pumpsTo SEPCS. share common provide intakereliability, increased and discharge headers the chiller units but are on the secondary loops include excess capacity with the ability to cross-tie between each SFP's secondary loops. Equipment for the secondary loop (which includes two chillers, a surge tank, two secondary pumps, electrical distribution panel, piping, valves, electrical wiring, conduit and instrumentation) is being added (i.e., is not re-purposed existing equipment). Except for some conduit, wiring and the small portion of piping to and from the primary heat exchanger, the secondary equipment will be installed outdoors between the Unit 2 and 3 fuel handling buildings. Piping installation and inspections will be performed per ANSI B31.1-2007. The ISEPCS primary cooling loop will be installed on the refueling floor in the new fuel area. The ISFPCS primary loop takes suction from the upender pit area of the SFP, pumps the warm water through a stainless steel, plate and frame, heat exchanger for cooling and then returns it to the SEP through the existing sparger. The ISEPCS suction has been located separate from that of the SFPCS to facilitate construction and testing without impacting SFPCS operation. The 1SFPCS is independent of the SFPCS except for a portion of the primary discharge, piping from the heat exchanger to the sparger connection. The new equipment will be installed inside the existing New Fuel Room. The primary pumps will add to the heat loading in the room. However, the existing HVAC equipment has sufficient margin available to appropriately control the environment to within its design temperature. To support fuel movement during future pool-to-pad campaigns or otherwise, the ISFPCS includes a side-stream purification loop including a new ion exchanger for purification. SEP Island Redundancy The SEP Island includes'two 100% capacity primary loop pumps. One heat exchanger is available, with a replacement heat exchanger readily available for installation in either SEP. The secondary loop provides two 100% capacity pumps and two chillers with excess capacity. Cross-tie capability is provided such that two chillers provide sufficient capability for both SFPs. SEP Island Electrical Power The SEP Island primary and secondary pumps, chillers, and other components will initially be powered from the existing plant electrical distribution system that has EDG backup power. Separately from the ISEPCS, Southern California Edison (SCE) is planning to install a non-safety Seismic Category Ill Decommissioning Power Ring System to facilitate decommissioning of various planit systems. This ring will be powered from offsite sources with a manual backup diesel generator. The Decommissioning Power Ring System will also power the ISEPCS. The transition to powering the ISFPCS from the Decommissioning Power Ring System will not occur until a manual start diesel back-up is available.

SEP Island Seismic Desiqn The SEP Island is designed to be non safety-related and Seismic Category Ill. The SFP* Island will be designed and installed such that the potential failure of any of its components (e.g. a suction or return piping) during a seismic event will not damage safety-related SSCs (e.g., the spent fuel storage racks) nor have an effect on the SEP water inventory resulting in uncovering of the spent fuel. SEP Island Quality Class The SEP Island is designed to meet the same Quality Group and Quality Class as the existing configuration. The SEP Island will be Quality Group D and Quality Class III-AQ. System Capacity The SFPCS primary heat exchangers are capable of removing 31 M-BTU/hr. They were sized based on decay heat loads associated with an operating' plant and therefore are far in excess needed currently for SONGS Units 2 and 3. The new ISFPCS primary heat exchanger is capable of removing 3.0 M-BTU/hr. It was sized based on current heat loads as reported in Table 9.1-lB of the UFSAR. The current heat load from all stored fuel and one dry storage container is conservatively projected to be approximately 2.6 M- BTU/hr for the limiting pool (SONGS Unit 2) and will continue to decrease over time as the fission products decay further. Instrumentation and Controls The current SFPCS provides Main Control Room alarms for high SEP temperature, high and low SEP level, low SEP pump discharge pressure and high radiation in the SEP area to alert the operator to abnormal circumstances. Additional level indication is available locally and in the Main Control Room/Command Center. Control for the primary and secondary loops of the ISFPCS is provided via the programmable logic controllers (PLCs) and local manual operation. Indications for primary loop process pressure, temperature and flow, ion exchanger flow, and SEP level will be provided in the Main Control Room/Command Center. The cooling water supplied by the chiller system is maintained at least 5 psid above the primary side pressure in the heat exchanger. If the differential pressure falls below 5 psid the primary pump is automatically shutdown to prevent migration of radioactivity from the primary to secondary side of the ISFPCS in the event of a leak in the heat exchanger. This trip also prevents the dilution of the SEP boron concentration by unborated water from the secondary side. If the temperature in the secondary side exceeds 100°F, the secondary pump shuts off. All other ISFPCS control functions are performed manually and locally. SEP Make-up Due to the significant reduction in SEP heat load since the final plant shutdown, and the reduction in potential boundary dose consequences in the few remaining credible events, the

SFP makeup functional requirements are reduced. Based on industry decommissioning experience, the use of independent systems for providing SEP cooling and inventory makeup, will reduce the potential for decommissioning activities to inadvertently damage installed plant SFP-related components which could result in a loss of SEP cooling or pool inventory. SCE will modify existing equipment to provide independent SEP makeup capability during decommissioning. To ensure the SEP inventory makeup is mnaintained, the SEP Enhanced Inventory Makeup design will include features that enhance makeup function reliability including redundancy, redundant power sources, and system cross-tie capabilities. The mechanical portion of the SONGS Units 2 and 3 permanent SEP Enhanced Inventory Makeup system will be seismically-qualified, and also has proceduralized the use of multiple and diverse means to provide backup spent fuel pool makeup to support the function of maintaining level within the pool. The robust design and construction of the spent fuel pool, multiple and diverse means for makeup, and the available time for response measures should a challenge to the stored fuel occur provides adequate defense-in-depth to protect public health and safety allowing the SEP Make-up system to be classified as Quality Group 0, important to safety. The SEP Makeup system being installed and the ISEPCS are both shown in the attached schematic. Each pool's permanent SEP Enhanced Inventory Makeup system relies on re-purposing the permanently installed Primary Plant Make-up Water Storage Tank located in the associated Rad Waste Building, with a combination of re-purposed smaller pump and new larger Seismic Category 1 qualified electric pumps and piping. The SONGS Mitigating Strategies include a tank (located in the North Industrial Area and previously associated with Unit 1) designed and constructed to ASME Rules and has a capacity of 150,000 gallons. This mitigation strategy also relies on a dedicated 2500 gpm diesel driven pump, on wheels that is located directly adjacent to the tank and positioned for use. The diesel driven pump equipment was purchased with seismic qualification. The mitigation system also includes hose connects from the fire pump to a Seismic Category I Eire Riser via a connection accessible through a door on the plant east road at grade (el. 30 ft). Another hose from a Fire Riser connection located adjacent to the door into the Fuel Pool Operating Deck (at elevation 60 ft.) directs the water into the Spent Fuel Pool. The hoses between the Tank and Pumper and Pumper and Riser are safely stored to preclude any damage during a seismic event. These hoses are routinely inspected and tested, procedures are in place for setup and use, and dry runs have been conducted showing installation of the backup mitigation makeup system can be done in less than 2 hours. All components are either installed or safely stored for use with minimal manual action. The previous Unit 2/3 Makeup Source, the Refueling Water Storage Tank (RWST) also required manual actions to align the system. The manual action for the previous SONGS Units 2 and 3 RWST could be accomplished in approximately one half hour when boiling could occur within two and one half hours, and the manual actions for the current mitigating strategies are less than two hours when boiling could occur after one hundred hours. In addition to the Seismic Category I make-up source, currently there are numerous other sources of makeup for the SFPs, including:

  • As provided in SONGS Units 2 and 3 procedures, the Nuclear Service Water connections located on the SEP operating level can be used via hoses to fill the pool.

These connections are QC III, Seismic Category I1. 

      *As provided in SONGS Units 2 and 3 Mitigation Strategies, water from Fire Water Tanks T-102 and T-103 via Fire Pumps P-220 (diesel driven), P-221 or P-222 (both of which are motor driven) can be provided through the installed fire system piping to 2 fire hose cabinets located on the Spent Fuel Pool Operating level. The tanks, pumps and piping are QC III-FPS and Seismic Category II.
      *As provided in SONGS Units 2 and 3 Mitigation Strategies, makeup to the SFPs can be provided using water from one or more of the following sources: Demineralized Water Tanks T-266, T-267 or T-268, all are located at a higher elevation at the Makeup Demineralizer Area at the south end of the plant. Skid mounted pump P-I1058 delivers water from these sources to the seismic standpipe and from the standpipe to the SFP.

T-266, T-267 and T-268 are QC Ill, Seismic Category I1.P-1058 is QC III-FPS and Seismic Category Ill.

  • As discussed in SONGS Units 2 and 3 Mitigation Strategies, the 10" City Water Line Supply Line can be used as an alternate source of SFP makeup water.
      *Another makeup path is available using the Seismic Category I Demineralized Water Storage Tank (T-351) located in the North Industrial Area along with Seismic Category I portable diesel driven Fire Pump (P-I1065) using strategically staged hoses between the tank, pump, Seismic Category I standpipe and the Spent Fuel Pool. The hoses are pressure tested annually and are inspected for location quarterly per SONGS Units 2 and 3 procedures.                                   _

The Mitigatio~n Strategies are sequenced to assure the strategies can be deployed in 2 hours or less. The capability to achieve this time requirement was evaluated in a formal study and further demonstrated in the field using actual staff, procedures and equipment. Operation Once the LAR is approved, a turnover to Operations of ISFPCS is acceptable. The SFPCS will remain functional until the complete scope of the modification has been turned over to Operations and both systems may continue to be available for several weeks depending on system performance and other plant conditions.

SFP BUILDING __________PRIMARY FLOW SPENT FUEL POOL PRMR ET XHNE SHOS _ CONNECTION (OUTSIDE FUEL HANDLING SLOG)CHLR 

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  • CHILLUFt CRO8STIIE TO OTHER UNIT I1 SECONDARY FLOW PROPOSED SPENT FUEL POOL COOLING AND INVENTORY MAKEUP (DECOMMISSIONING)

'I" S0UTHEI*N CALIFORNIA U IU~'J'I\~Manager, Regulatory Affairs An EDISON INThqRNAgTONAL".' Cornpany 10 CFR 50.90 January 12, 2016 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555-0001

Subject:

Docket Nos. 50-361 and 50-362 Response to a Second Request for Additional Information Regarding Amendment Applications 270 and 255 SProposed Changes to Specific Regulatory Guide Commitments San Onofre Nuclear Generating Station, Units 2 and 3

References:

1) Letter from T. J. Palmisano (SCE) to the U. S. Nuclear Regulatory Commission (NRC) dated August 20, 2015;

Subject:

Docket Nos. 50-361 and 50-362, Amendment Applications 270 and 255, Proposed Changes to Specific Regulatory Guide Commitments, San Onofre Nuclear Generating Station, Units 2 and 3 (ADAMS Accession No. ML15236A018)

2) Letter from M. Vaaler (NRC) to T. J. Palmisano (SCE) dated December 22, 2015;

Subject:

San Onofre Nuclear Generating Station, Units 2 and 3-Second Request for Additional Information Regarding the License Amendment Request to Make Changes to Specific Regulatory Guide Commitments Related to the Implementation of "Cold and Dark" Status (CA NOS. L53073 and L53074) (ADAMS Accession No. ML15348A367)

Dear Sir or Madam:

By letter dated August 20, 2015 (Reference 1), Southern California Edison (SCE) submitted a License Amendment Request (LAR), consisting of Amendment Applications Nos. 270 and 255, to Facility Operating License Numbers NPF-1 0 and NPF-1 5 for San Onofre Nuclear Generating Station (SONGS) Units 2 and 3, respectively. The LAR proposed to revise the Updated Final Safety Analysis Report (UFSAR) to revise specific Regulatory Guide commitments. By letter dated December 22, 2015 (Reference 2), the NRC provided a Second Request for Additional Information (RAI) regarding Reference 1. The response to the Second RAI is 

       *contained in Enclosure 1 to this letter.

Additionally, several concerns with the details in Reference 1 were identified in a recent NRC inspection. These concerns have been addressed in a revision to Reference 1, Attachment A, Proposed Changes to Specific Regulatory Guide Commitments, Spent Fuel Pool 'Island' Description. The revised information is provided as Enclosure 2 to this letter. P. O. Box 128 *-{ San Glemente, CA 92672

Document Control Desk The additional information provided in the enclosures does not affect the conclusions of the No Significant Hazards Consideration or the Environmental Consideration provided in Reference 1. There are no new regulatory commitments in this letter or the Enclosures. If you have any questions or require any additional information, please contact me at (949) 368-7418. Sincerely,

Enclosures:

1. Response to NRC Second Request for Additional Information
2. Revision to Attachment A of Proposed Changes to Specific Regulatory Guide Commitments cc: M. L. Dapas, Regional Administrator, NRC Region IV M. G. Vaaler, NRC Project Manager, SONGS Units 2 & 3 S. Y. Hsu, California Department of Public Health, Radiologic Health Branch 2

ENCLOSURE 1 RESPONSE TO NRC SECOND REQUEST FOR ADDITIONAL INFORMATION SAN ONOFRE NUCLEAR GENERATING STATION, UNITS 2 AND 3

SECOND REQUEST FOR ADDITIONAL INFORMATION PROPOSED CHANGES TO SPECIFIC REGULATORY GUIDE COMMITMENTS SOUTHERN CALIFORNIA EDISON SAN ONOFRE NUCLEAR GENERATING STATION. UNITS 2 AND 3 DOCKET NOS. 50-361 AND 50-362 By letter dated August 20, 2015 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML15236A018), as supplemented by responses to an initial request for additional information provided by letter dated November 19, 2015 (ADAMS Accession No. ML15327A410), Southern California Edison (SCE) requested an amendment to the facility operating licenses for the San Onofre Nuclear Generating Station, Units 2 and 3 (SONGS). The proposed amendment would revise Appendix 3A of the Updated Final Safety Analysis Report (UFSAR) to more fully reflect the permanently shutdown status of SONGS. The revision would include a limited set of exceptions and clarifications to referenced Regulatory Guides to reflect the significantly reduced decay heat loads in the SONGS Units 2 and 3 spent fuel pools and to support corresponding design basis changes and modifications that will allow for implementation of the "cold and dark" strategy outlined in the SONGS Post-Shutdown Decommissioning Activities Report (PSDAR). The following additional information is necessary to complete the NRC staff's technical review: REQUESTS FOR ADDITIONAL INFORMATION

4. Design Feature Technical Specification for Drainage Prevention General Design Criterion (GDC) 61, "Fuel Storage and Handling and Radioactivity Control,"

of Appendix A, "General Design Criteria for Nuclear Power Plants," to Title 10 of the Code of Federal Regulations(10 CFR), Part 50, states in part that fuel storage facilities shall be designed to prevent a significant reduction in fuel storage coolant inventory under accident conditions. In addition to capabilities described in the SONGS UFSAR, this criterion has been incorporated in the SONGS Facility Operating License as Technical Specification (TS) 4.3.2, "Drainage," in Section 4, "Design Features," which states: The spent fuel storage pool is designed and shall be maintained to prevent inadvertent draining of the pool below Technical Specification 3.1.1 value (23 feet above the top of irradiated fuel assemblies seated in the storage racks). The requirements of 10 CFR 50.36(c)(4), "Design Features,"specify that the design features to be included in the TSs are those features of the facility such as materials of construction or geometric arrangements, which, if altered or modified, would have a significant effect on safety and are not included in other portions of the TSs. In Attachment 3 to the letter dated November 19, 2015, SCE provided a spent fuel pooi level correlation that indicated the centerline of the spent fuel pool cooling suction line was located at an elevation below the level specified in TS 4.3.2. Since the spent fuel pool cooling suction line could drain or siphon coolant from the spent fuel pool volume inside the fuel transfer and cask loading area gates, the level specified in TS 4.3.2 (23 feet above the top of irradiated fuel assemblies seated in the storage racks) does not conform with the geometric arrangement of drainage prevention features provided for spent fuel pool piping penetrations and attached piping. Accordingly, please propose a revision to TS 4.3.2 that conforms to the geometric arrangement of piping penetrations and siphon protection design features within the spent fuel pool, or explain how inadvertent drainage to the level specified in TS 4.3.2 through the spent fuel pool cooling system suction piping and the independent spent fuel pool cooling system suction line is not possible. sCE Response The existing spent fuel pool (SFP) suction line configuration has not changed since the original plant design, construction, operation and licensing. The Safety Evaluation Report related to the operation of San Onofre Nuclear Generation Station Units 2 and 3 (Reference 1) Section 9.1 3 states that the NRC has reviewed the design of the Spent Fuel Pool and found it acceptable. 

    "We have reviewed the design of the spent fuel cooling and cleanup system and conclude that it meets the requirements of... General Design Criteria 61 as related to fuel storage systems design with provisions for containment of radioactive materials and decay heat removal. We further conclude that the system design meets the guidelines of Regulatory Guides 1.13, "Spent Fuel Storage Design Basis" regarding...prevention of excessive fuel pool water loss."

The content of the Units 2 and 3 Design Features Technical Specifications were initially based on plant elevation (specifically referenced 60' 6"). During the licensing of high density racks (Amendment No. 87 for SONGS Unit 2 and No. 77 for SONGS Unit 3 / March 10 1989 - May 1, 1990) a decision was made to revise the limit to 23 feet above the spent fuel assemblies. That value corresponds to Standard and improved Technical Specification content and the initial SONGS Limiting Condition for Operation (LCO) value, which preserves the conditions to use generic decontamination factors when calculating dose consequences of a Fuel Handling Accident (FHA) addressed historically by Regulatory Guide 1.25 and currently by Regulatory Guide 1.183. The analysis that credits these decontamination factors is associated with fuel handling operations and thus is more appropriately tied to the LCO than the Design Feature. SCE recently surveyed peer decommissioning plants and the results further Suggest that the LCO limit of 23 feet (SONGS TS 3.1.1) applicable during fuel movement is used to protect this safety analysis input. After re-reviewing the cited requirements, related guidance, peer Technical Specification content and previous interactions with the NRC, SCE considers the existing configuration, TS content, and other characteristics to fully meet the fundamental functional requirements and the GDC. Among those characteristics are the following: 

 *The safety purposes of the LCO minimum level include decontamination of releases from a FHA, shielding and cooling under a variety of conditions.
 *While the current system is in operation, the suction line has to remain available. SONGS Units 2 and 3 UFSAR Section 9.1.3.3 "Safety Evaluation" notes that: "Inadvertent draining of the SEP, including siphoning, below approximately 23 feet above the stored fuel is prevented by design features (siphon breakers and check valves, etc.) and Administrative Controls." These include low pool level and high sump level alarms..
 *The suction line is a moderate (i.e., not high) energy line designed to Seismic Category I requirements and thus not postulated to fail as noted in the SONGS Units 2 and 3 UFSAR Appendix 3.6B.
 *Consistent with the classification of the spent fuel pool and liner, the existing suction line from the pool through the first isolation valve (MU 102) is classified as safety-related. The balance of the line is classified as Augmented Quality (III-AQ) which imposes most Appendix B criteria (design control, etc. as described in the SONGS Units 2 and 3 Q-List, 90034).

There are also administrative requirements to close valves or take other manual actions if required. , 

 *Finally, and perhaps most importantly, oversight of the SEP conditions (level, radiation levels, etc.) are the most safety significant focus of the SONGS staff. Thus, malfunction of the system will be promptly recognized and corrected.

In conclusion, the cited Technical Specification Design Feature is used in conjunction with an LCO which is applicable "during movement of fuel assemblies in the spent fuel pool." SCE will maintain appropriate design features, administrative controls, alarm values and alarm response protocols; therefore, the value in the Technical Specification Design Features 4.3.2, while quite conservative, does not need to be changed.

5. Makeup Water In its response to RAI-SBPB-01, SCE described that any liner leaks into the leak chase would be limited to approximately 50 gallons/minute, which is within the capacity of the identified makeup capability, and that such leaks could also be mitigated by shutting the leak chase drain valves if appropriate to do so.

For design basis events that could cause a minor liner leak, such as a fuel handling accident, estimate the time available to take mitigating actions prior to the spent fuel water level decreasing to the point shielding may be ineffective (e.g., 10 feet above the top of stored fuel). Based on the available time, provide justification that appropriate makeup can be delivered to the spent fuel pool with a high probability of success before shielding of the fuel becomes ineffective. SCE Response There are no design basis events that result in penetration of the liner. The subject of a FHA not leading to liner failure was addressed in the "licensing of the high density racks (License Amendment Request Licensing Report Section 4.6.4.3.2, Reference 2 and Safety Evaluation Technical Report Section 4.3, Reference 3) and it was demonstrated that the dropped fuel assembly would not adversely impact the SFP liner and the liner would not be perforated. The SEP design is such that the steel liner is in direct contact with the concrete floor or walls. The leak chases are embedded into the concrete. Nevertheless, SCE has calculated the time for a non-mechanistic liner penetration causing a 50 gpm leak not terminated by isolation of the leak chases to reach a level of 10 feet above the fuel assemblies. With both gates open (the current and most likely configuration); the leak would drain the pool to 10 feet in -70 hours. The installed makeup systems can be started promptly and, if unavailable, the multiple back-up Mitigation Strategies can be placed in-service in less than two hours which has been demonstrated using minimum on-site staffing.

6. Island Spent Fuel Pool Cooling System In its response to RAI-SBPB-O1, SCE described that the proposed independent spent fuel pool cooling system independently takes suction from the spent fuel transfer pool through a pipe that extends from the operating floor down to the same elevation as the existing spent fuel pool cooling suction line.

GDC 61 states in part that fuel storage facilities shall be designed with a residual heat removal capability having reliability and testability that reflects the importance to safety of decay heat and other residual heat removal. Since the proposed independent spent fuel pool cooling system would draw water vertically from the transfer canal, address the effect of the suction design and location on the reliability of spent fuel pool cooling compared to the existing cooling system. Specifically, explain whether available net positive suction head would be adequate to restore forced cooling following an extended loss of cooling with the resulting increase in spent fuel pool temperature and whether transfer gate closure would interfere with cooling for an extended period. Justify the adequacy of the proposed independent cooling system design relative to GDC 61 considering these potential limitations on cooling system reliability. SCE Response: The concern associated with suction design and location relative to restart of the pumps after an extended loss of cooling has been evaluated for reliability. It is likely that the SFP would never reach temperatures where pump restart is challenged (i.e. greater than 1900 F) however, SCE has not performed a formal and rigorously conservative analysis to determine the equilibrium temperature possible as the fuel continues to decay. Rather than relying on calculation outcomes alone, primary pump NPSH concerns have been addressed by establishing temperature limits for restart and by a procedure provision to add cold water via the makeup system before pump restart, if required. Throttling secondary flow is also considered for continued chiller operation. Temperature monitoring will also indicate approach to limits and allow for any necessary actions to maintain adequate suction conditions for the pumps and chillers. There are no current plans to install a transfer gate. Provisions will exist for conditions if a transfer gate is installed. In this case, a temporary suction line would be connected to flanged connections to move the suction to the main part of the spent fuel pool as part of the system design. References

1) NUREG-071 2, Safety Evaluation Report related to the operation of San Onofre Nuclear Generating Station, Units 2 and 3,dated February, 1981
2) Letter From F. R. Nandy, SCE to the Nuclear Regulatory Commission dated April 19, 1 989,

Subject:

Spent Fuel Pool Reracking Amendment Application Nos. 78 and 64 (PCN-287)

3) Letter from L. E. Kokajko, NRC to H. B. Ray, SCE dated May 1, 1990,

Subject:

Issuance of Amendment No. 87 to Facility Operating License No. NPF-1 0 and Amendment No. 77 to Facility Operating License No. NPF-15, San Onofre Nuclear Generating Station Unit N~s. 2 and 3 ENCLOSURE 2 REVISION TO ATTACHMENT A OF PROPOSED CHANGES TO SPECIFIC REGULATORY GUIDE COMMITMENTS SAN ONOFRE NUCLEAR GENERATING STATION, UNITS 2 AND 3

Attachment A Spent Fuel Pool 'Island' Description Back~Qround Due to the significant reduction in Spent Fuel Pool (SEP) heat load since final plant shutdown and the reduction in potential boundary dose consequences for the few remaining credible events, the SEP cooling functional requirements are reduced. Based on industry decommissioning experience, the use of independent non-plant systems for providing SFP cooling will reduce the potential for decommissioning activities to inadvertently damage installed plant SEP-related components which could result in a loss of SEP cooling or pool inventory. San Onofre Nuclear Generating Station (SONGS) Units 2 and 3 will design and install an independent SEP cooling and purification system. This SEP cooling and purification system is referred to as the SEP Island. To safely maintain SEP cooling, the SEP Island design includes features that support cooling function reliability including component redundancy, redundant power sources, and system cross-tie capabilities. Current SFPCS Each unit of the current Spent Fuel Pool Cooling System (SFPCS) consists of two loops, the Spent Fuel Pool (SEP) cooling loop and the purification loop. The SFPCS is normally controlled manually from the main control panel. Main Control Room alarms for high SEP temperature, high and low SEP level, low SEP pump discharge pressure and, high radiation S.in the SEP area, are provided to alert the operator to abnormal circumstances. A local alarm for low SEP level is also provided. The SFPCS consists of two 100% capacity SEP pumps and two 100% capacity SEP heat exchangers. The two SEP pumps are connected to a common suction header and a common return header. The SEP05 also includes appropriate valves, piping, and instrumentation. SEP water is circulated by the SEP pumps through the SEP heat exchangers where it is cooled. The heat is rejected to the Component Cooling Water (CCW) System, which, in turn, rejects heat to the Salt Water Cooling system and ultimately to the Pacific Ocean. Neither the CCW nor SWC systems are otherwise impacted by this modification. The SFPCS includes a purification loop that has been administratively removed from service and the resin removed. The Independent Spent Fuel Pool Cooling System (ISFPCS) will be installed, tested and provide run-in time prior to removing the current system from operation. Thus, the ISFPCS will be operating and the current Spent Euel Pool Cooling System will be maintained as a fully-functional back-up. SEP Island System Overview ISEPCS is shown in the attached schematic. The design will include one primary loop per SEP. Each primary loop includes two 100% capacity pumps with a common intake and discharge header and a single heat exchanger. Replacement heat exchangers are readily available. There will be one secondary loop per SEP with a common intake and discharge he ader. The secondary loop is a closed system that uses air cooled chillers to cool the secondary side water. Each secondary loop will consist of two 100% capacity pumps. Both

the primary and independent fromsecondary loop the current pumpsTo SEPCS. share common provide intakereliability, increased and discharge headers the chiller units but are on the secondary loops include excess capacity with the ability to cross-tie between each SFP's secondary loops. Equipment for the secondary loop (which includes two chillers, a surge tank, two secondary pumps, electrical distribution panel, piping, valves, electrical wiring, conduit and instrumentation) is being added (i.e., is not re-purposed existing equipment). Except for some conduit, wiring and the small portion of piping to and from the primary heat exchanger, the secondary equipment will be installed outdoors between the Unit 2 and 3 fuel handling buildings. Piping installation and inspections will be performed per ANSI B31.1-2007. The ISEPCS primary cooling loop will be installed on the refueling floor in the new fuel area. The ISFPCS primary loop takes suction from the upender pit area of the SFP, pumps the warm water through a stainless steel, plate and frame, heat exchanger for cooling and then returns it to the SEP through the existing sparger. The ISEPCS suction has been located separate from that of the SFPCS to facilitate construction and testing without impacting SFPCS operation. The 1SFPCS is independent of the SFPCS except for a portion of the primary discharge, piping from the heat exchanger to the sparger connection. The new equipment will be installed inside the existing New Fuel Room. The primary pumps will add to the heat loading in the room. However, the existing HVAC equipment has sufficient margin available to appropriately control the environment to within its design temperature. To support fuel movement during future pool-to-pad campaigns or otherwise, the ISFPCS includes a side-stream purification loop including a new ion exchanger for purification. SEP Island Redundancy The SEP Island includes'two 100% capacity primary loop pumps. One heat exchanger is available, with a replacement heat exchanger readily available for installation in either SEP. The secondary loop provides two 100% capacity pumps and two chillers with excess capacity. Cross-tie capability is provided such that two chillers provide sufficient capability for both SFPs. SEP Island Electrical Power The SEP Island primary and secondary pumps, chillers, and other components will initially be powered from the existing plant electrical distribution system that has EDG backup power. Separately from the ISEPCS, Southern California Edison (SCE) is planning to install a non-safety Seismic Category Ill Decommissioning Power Ring System to facilitate decommissioning of various planit systems. This ring will be powered from offsite sources with a manual backup diesel generator. The Decommissioning Power Ring System will also power the ISEPCS. The transition to powering the ISFPCS from the Decommissioning Power Ring System will not occur until a manual start diesel back-up is available.

SEP Island Seismic Desiqn The SEP Island is designed to be non safety-related and Seismic Category Ill. The SFP* Island will be designed and installed such that the potential failure of any of its components (e.g. a suction or return piping) during a seismic event will not damage safety-related SSCs (e.g., the spent fuel storage racks) nor have an effect on the SEP water inventory resulting in uncovering of the spent fuel. SEP Island Quality Class The SEP Island is designed to meet the same Quality Group and Quality Class as the existing configuration. The SEP Island will be Quality Group D and Quality Class III-AQ. System Capacity The SFPCS primary heat exchangers are capable of removing 31 M-BTU/hr. They were sized based on decay heat loads associated with an operating' plant and therefore are far in excess needed currently for SONGS Units 2 and 3. The new ISFPCS primary heat exchanger is capable of removing 3.0 M-BTU/hr. It was sized based on current heat loads as reported in Table 9.1-lB of the UFSAR. The current heat load from all stored fuel and one dry storage container is conservatively projected to be approximately 2.6 M- BTU/hr for the limiting pool (SONGS Unit 2) and will continue to decrease over time as the fission products decay further. Instrumentation and Controls The current SFPCS provides Main Control Room alarms for high SEP temperature, high and low SEP level, low SEP pump discharge pressure and high radiation in the SEP area to alert the operator to abnormal circumstances. Additional level indication is available locally and in the Main Control Room/Command Center. Control for the primary and secondary loops of the ISFPCS is provided via the programmable logic controllers (PLCs) and local manual operation. Indications for primary loop process pressure, temperature and flow, ion exchanger flow, and SEP level will be provided in the Main Control Room/Command Center. The cooling water supplied by the chiller system is maintained at least 5 psid above the primary side pressure in the heat exchanger. If the differential pressure falls below 5 psid the primary pump is automatically shutdown to prevent migration of radioactivity from the primary to secondary side of the ISFPCS in the event of a leak in the heat exchanger. This trip also prevents the dilution of the SEP boron concentration by unborated water from the secondary side. If the temperature in the secondary side exceeds 100°F, the secondary pump shuts off. All other ISFPCS control functions are performed manually and locally. SEP Make-up Due to the significant reduction in SEP heat load since the final plant shutdown, and the reduction in potential boundary dose consequences in the few remaining credible events, the

SFP makeup functional requirements are reduced. Based on industry decommissioning experience, the use of independent systems for providing SEP cooling and inventory makeup, will reduce the potential for decommissioning activities to inadvertently damage installed plant SFP-related components which could result in a loss of SEP cooling or pool inventory. SCE will modify existing equipment to provide independent SEP makeup capability during decommissioning. To ensure the SEP inventory makeup is mnaintained, the SEP Enhanced Inventory Makeup design will include features that enhance makeup function reliability including redundancy, redundant power sources, and system cross-tie capabilities. The mechanical portion of the SONGS Units 2 and 3 permanent SEP Enhanced Inventory Makeup system will be seismically-qualified, and also has proceduralized the use of multiple and diverse means to provide backup spent fuel pool makeup to support the function of maintaining level within the pool. The robust design and construction of the spent fuel pool, multiple and diverse means for makeup, and the available time for response measures should a challenge to the stored fuel occur provides adequate defense-in-depth to protect public health and safety allowing the SEP Make-up system to be classified as Quality Group 0, important to safety. The SEP Makeup system being installed and the ISEPCS are both shown in the attached schematic. Each pool's permanent SEP Enhanced Inventory Makeup system relies on re-purposing the permanently installed Primary Plant Make-up Water Storage Tank located in the associated Rad Waste Building, with a combination of re-purposed smaller pump and new larger Seismic Category 1 qualified electric pumps and piping. The SONGS Mitigating Strategies include a tank (located in the North Industrial Area and previously associated with Unit 1) designed and constructed to ASME Rules and has a capacity of 150,000 gallons. This mitigation strategy also relies on a dedicated 2500 gpm diesel driven pump, on wheels that is located directly adjacent to the tank and positioned for use. The diesel driven pump equipment was purchased with seismic qualification. The mitigation system also includes hose connects from the fire pump to a Seismic Category I Eire Riser via a connection accessible through a door on the plant east road at grade (el. 30 ft). Another hose from a Fire Riser connection located adjacent to the door into the Fuel Pool Operating Deck (at elevation 60 ft.) directs the water into the Spent Fuel Pool. The hoses between the Tank and Pumper and Pumper and Riser are safely stored to preclude any damage during a seismic event. These hoses are routinely inspected and tested, procedures are in place for setup and use, and dry runs have been conducted showing installation of the backup mitigation makeup system can be done in less than 2 hours. All components are either installed or safely stored for use with minimal manual action. The previous Unit 2/3 Makeup Source, the Refueling Water Storage Tank (RWST) also required manual actions to align the system. The manual action for the previous SONGS Units 2 and 3 RWST could be accomplished in approximately one half hour when boiling could occur within two and one half hours, and the manual actions for the current mitigating strategies are less than two hours when boiling could occur after one hundred hours. In addition to the Seismic Category I make-up source, currently there are numerous other sources of makeup for the SFPs, including:

  • As provided in SONGS Units 2 and 3 procedures, the Nuclear Service Water connections located on the SEP operating level can be used via hoses to fill the pool.

These connections are QC III, Seismic Category I1. 

      *As provided in SONGS Units 2 and 3 Mitigation Strategies, water from Fire Water Tanks T-102 and T-103 via Fire Pumps P-220 (diesel driven), P-221 or P-222 (both of which are motor driven) can be provided through the installed fire system piping to 2 fire hose cabinets located on the Spent Fuel Pool Operating level. The tanks, pumps and piping are QC III-FPS and Seismic Category II.
      *As provided in SONGS Units 2 and 3 Mitigation Strategies, makeup to the SFPs can be provided using water from one or more of the following sources: Demineralized Water Tanks T-266, T-267 or T-268, all are located at a higher elevation at the Makeup Demineralizer Area at the south end of the plant. Skid mounted pump P-I1058 delivers water from these sources to the seismic standpipe and from the standpipe to the SFP.

T-266, T-267 and T-268 are QC Ill, Seismic Category I1.P-1058 is QC III-FPS and Seismic Category Ill.

  • As discussed in SONGS Units 2 and 3 Mitigation Strategies, the 10" City Water Line Supply Line can be used as an alternate source of SFP makeup water.
      *Another makeup path is available using the Seismic Category I Demineralized Water Storage Tank (T-351) located in the North Industrial Area along with Seismic Category I portable diesel driven Fire Pump (P-I1065) using strategically staged hoses between the tank, pump, Seismic Category I standpipe and the Spent Fuel Pool. The hoses are pressure tested annually and are inspected for location quarterly per SONGS Units 2 and 3 procedures.                                   _

The Mitigatio~n Strategies are sequenced to assure the strategies can be deployed in 2 hours or less. The capability to achieve this time requirement was evaluated in a formal study and further demonstrated in the field using actual staff, procedures and equipment. Operation Once the LAR is approved, a turnover to Operations of ISFPCS is acceptable. The SFPCS will remain functional until the complete scope of the modification has been turned over to Operations and both systems may continue to be available for several weeks depending on system performance and other plant conditions.

SFP BUILDING __________PRIMARY FLOW SPENT FUEL POOL PRMR ET XHNE SHOS _ CONNECTION (OUTSIDE FUEL HANDLING SLOG)CHLR 

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  • CHILLUFt CRO8STIIE TO OTHER UNIT I1 SECONDARY FLOW PROPOSED SPENT FUEL POOL COOLING AND INVENTORY MAKEUP (DECOMMISSIONING)}}
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