ML17158A164

Requests Addl Info Re Standby Gas Treatment Sys Performance at Susquehanna Steam Electric Station,Units 1 & 2

ML17158A164
Person / Time
Site:	Susquehanna
Issue date:	03/07/1994
From:	James Shea Office of Nuclear Reactor Regulation
To:	Byram R PENNSYLVANIA POWER & LIGHT CO.
References
TAC-M85337, NUDOCS 9403100171
Download: ML17158A164 (9)

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UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 2055&0001 Harch 7, 1994 Docket Nos.

50-387 and 50-388 Hr. Robert G.

Byram Senior Vice President-Nuclear Pennsylvania Power and Light Company 2 North Ninth Street Allentown, Pennsylvania 18101

SUBJECT:

REQUEST FOR ADDITIONAL INFORHATION (RAI) CONCERNING STANDBY GAS TREATHENT SYSTEH PERFORMANCE, SUS(UEHANNA STEAN ELECTRIC STATION, UNITS 1

AND 2 (TAC NO. 85337)

The NRC staff is reviewing information on spent fuel pool cooling issues raised in a report filed pursuant to 10 CFR Part 21 on November 27, 1992.

In

'rder to thoroughly and methodically evaluate the issues, the staff developed a Task Action Plan, dated November 15, 1993.

By letter to Hessrs.

Lochbaum and Prevatte dated November 17,

1993, a copy of the Task Action Plan was forwarded to you.

Item LC-9 of the action plan provided for a review of that portion of the existing licensing basis for Susquehanna Steam Electric Station (SSES),

Units 1 and 2, as it related to cooling of the spent fuel pool.

The staff has completed the licensing basis review.

The review examined the existing licensing relationship between loss-of-coolant accidents (LOCA), loss-of-offsite power events and loss of spent fuel pool cooling events.

The review also examined the existing licensing basis for various systems that might be used to mitigate a loss-of-spent fuel pool cooling event.

The staff is preparing a comprehensive summary of the licensing basis review and expects that it will be available in the near future.

As a result of the licensing basis review,

however, the staff has determined that additional information regarding the performance of the standby gas treatment system (SGTS) is required for the staff to complete the overall spent fuel pool cooling review.

The request for additional information is included as an enclosure.

Section 3.2. 1 of the SSES Safety Evaluation Report (SER),

NUREG-0776, "Safety Evaluation Report Related to the Operation of Susquehanna Steam Electric

Station, Units 1 and 2," evaluated compliance of the SSES design to the requirements of General Design Criteria 2 related to seismic events.

The SER noted,six exceptions to the guidance of Regulatory Guide (RG) 1.29.

The second of those, in Section 3.2. 1(2) of the SER, determined that a nonseismic spent fuel pool cooling loop was acceptable based on the Seismic Category I

makeup supply from the emergency service water system.

Section 3.2. 1(2) of the SER further states:

"The nonseismic Category I classification of the cooling loop at the

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<., Hr. Robert G. Byram March 7 1994 handling area is ventilated by the seismic Category I standby gas treatment system which has engineered safety feature filters that meet the recommendations of Regulatory Guide 1.52, "Design, Maintenance Testing Criteria for Atmosphere Cleanup System Air Filtration and Adsorption Unit of Light-Mater-Cooled Nuclear Power Plants." Section C.l.a of RG 1.52 states: "The design of an engineered-safety-feature atmospheric cleanup system should be based on the maximum pressure differential, radiation dose rate, relative humidity, maximum and minimum temperature, and other conditions resulting from;the postulated DBA and on the duration of such condition." Appendix 9A of the SSES Final Safety Analysis Report (FSAR) evaluates the offsite dose consequences of a boiling spent fuel pool following a seismic event. In that analysis, the'icensee takes no credit for any filtration of the vapor coming off of the sp'ent fuel pool. ',The offsite dose consequences are determined to be within the requirements of 10 CFR Part 100. In the

SER, the staff acknowledges the acceptable offsite 'dose consequences evaluated by the licensee.

However, the staff cl'early links the acceptability of the nonseismic fuel pool cooling loops for a seismic event with the acceptable operation of the SGTS under boiling spent fuel pool conditions. I The staff concludes, therefore, that the ability of the SGTS to ventilate the fuel handling area during a boiling-,spent fuel pool event following a seismic event is considered within the existing licensing basis of the facility. As stated

above, the staff expects to have a comprehensive summary of the licensing basis as it relates to the issues raised in the Part 21 report available in the near future.

Your response to the enclosed questions is requested by March 25, 1994. This request affects fewer than 10 respondents and, therefore, is not subject ':to'ffice of Management and Budget review under P.L. 96-511. If you have any questions, please contact me at (301) 504-1428. Sincerely, /s/ Joseph W. Shea, Project Manager Project Directorate I-2 Division of Reactor Projects - I/II Office of Nuclear Reactor Regulation

Enclosure:

Request for Additional Information cc w/enclosure: See next page DISTRIBUTION w/encl osure Docket File JCalvo NRC and Local PDRs CHiller PDI-2 Reading MO'Brien SVarga JShea MVir i1io SJones RCl ark

JWhite, RGN-I OGC LPrividy, RGN-I ACRS(10)

GKelly, SPSB EWenzinger, RGN-I GHubbard, SPLB OFFICE PD I-2/ PD I.2/D P CHI I HAHE HO J ee 3/ /94 Q/7 94 94 DATE OFFICIAL CO COPY DOCUMENT NAME: SBGTRAI. LTR

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Mr. Robert G. Byram March 7, 1994 fuel pool cooling and cleanup system is acceptable since the fuel handling area is ventilated by the seismic Category I standby gas treatment system which has engineered safety feature filters that meet the recommendations of Regulatory Guide 1.52, "Design, Maintenance Testing Criteria for Atmosphere Cleanup System Air Filtration and Adsorption Unit of Light-Water-Cooled Nuclear Power Plants." Section C. l.a of RG 1.52 states: "The design of an engineered-safety-feature atmospheric cleanup system should be based on the maximum pressure differential, radiation dose rate, relative humidity, maximum and minimum temperature, and other conditions resulting from the postulated DBA and on the duration of such condition." Appendix 9A of the SSES Final Safety Analysis Report (FSAR) evaluates the offsite dose consequences of a boiling spent fuel pool following a seismic event. In that analysis, the licensee takes no credit for any filtration of. the vapor coming off of the spent fuel pool. The offsite dose consequences are determined to be within the requirements of 10 CFR Part 100. In the SER; the staff acknowledges the acceptable offsite dose consequences evaluated by. the licensee. However, the staff clearly links the acceptability of the nonseismic fuel pool cooling loops for a seismic event with the acceptable operation of the SGTS under boiling spent fuel pool conditions. The staff concludes, therefore, that the ability of the SGTS to ventilate the fuel handling area during a boiling spent fuel pool event following a seismic event is considered within the existing licensing basis of the facility. As stated

above, the staff expects to have a comprehensive summary of the licensing basis as it relates to the issues raised in the Part 21 report available in the near future.

Your response to the enclosed questions is requested by March 25, 1994. This request affects fewer than 10 respondents and, therefore, is not subject to Office of Management and Budget review under P.L. 96-511. If you have any questions, ease contact me at (301) 504-1428. Si cer

Enclosure:

Request for Additional Information cc w/enclosure: See next page se W. Shea, Project Manager roj ct Directorate I-2 ivision of Reactor Projects - I/II ffice of Nuclear Reactor Regulation

Pennsylvania Power 8 Light Company Susquehanna Steam Electric Station, Units 1 h 2 CC: Jay Silberg, Esq.

Shaw, Pittman, Potts

& Trowbridge 2300 N Street N.W. Washington, D.C. 20037 Bryan A. Snapp, Esq. Assistant Corporate Counsel Pennsylvania Power 5 Light Company 2 North Ninth Street Allentown, Pennsylvania 18101 Mr. J. M. Kenny Licensing Group Supervisor Pennsylvania Power E Light Company 2 North Ninth Street Allentown, Pennsylvania 18101 Mr. Scott Barber Senior Resident Inspector U. S. Nuclear Regulatory Commission P.O. Box 35 Berwick, Pennsylvania 18603-0035 Mr. Thomas M. Gerusky, Director Bureau of Radiation Protection Resources Commonwealth of Pennsylvania P. 0. Box 2063 Harrisburg, Pennsylvania 17120 Mr. Jesse C. Tilton, III Allegheny Elec. Cooperative, Inc. 212 Locust Street P.O. Box 1266 Harrisburg, Pennsylvania 17108-1266 Regional Administrator, Region I U.S. Nuclear Regulatory Commission 475 Allendale Road King of Prussia, Pennsylvania 19406 Mr. Harold G. Stanley Superintendent of Plant Susquehanna Steam Electric Station Pennsylvania Power and Light Company Box 467 Berwick, Pennsylvania 18603 Mr. Herbert D. Woodeshick Special Office of the President Pennsylvania Power and Light Company Rural Route 1, Box 1797 Berwick, Pennsylvania 18603 George T. Jones Manager-Engineering Pennsylvania Power and Light Company 2 North Ninth Street Allentown, Pennsylvania 18101 Robert G. Byram Senior Vice President-Nuclear Pennsylvania Power 5 Light Company 2 North Ninth Street Allentown, Pennsylvania 18101 Mr. David A. Lochbaum 80 Tuttle Road

Watchung, New Jersey 07060 Mr. Donald C. Prevatte 7924 Woodsbluff Run Fogelsville, Pennsylvania 18051

ENCLOSURE RE VEST FOR ADDITIONAL INFORMATION REGARDING LOSS OF SPENT FUEL POOL COOLING EVENTS 1. Based on the staff's evaluation of the licensing basis for Susquehanna Steam Electric Station (SSES), the staff concluded that the basis for acceptance of a non-seismic Category I spent fuel pool (SFP) cooling system was the provision of the seismic Category-I SFP makeup system and the provision of the seismic Category I standby gas treatment system (SGTS), which has engineered safety feature filters that meet the recommendations of Regulatory Guide (RG) 1.52, "Design, Testing, and Maintenance Criteria for Post Accident Engineered-Safety-Feature Atmosphere Cleanup System Air Filtration and Adsorption Units of Light-Water-Cooled Nuclear Power Plants." The regulatory position of Section C. l.a of RG 1.52 states in part that the design of an engineered-safety-feature atmospheric cleanup system should be based on the relative humidity, maximum temperature, and other conditions resulting from a postulated design basis accident. The offsite consequences of a total loss of SFP cooling caused by a seismic event were analyzed in Appendix 9A of the SSES FSAR. This analysis assumed that the residual heat removal (RHR) system was unavailable for spent fuel pool cooling, resulting in boiling of both spent fuel pools. Therefore, the. staff concluded that boiling of both spent fuel pools following a seismic event constituted a design basis accident. The staff reviewed an analysis by Pennsylvania Power & Light Company (PP&L), which evaluated the effect of spent fuel pool boiling on the SGTS during an inspection at PP&L's corporate headquarters on February 7, 1994. The staff determined that the analysis is not bounding for the design basis seismic event leading to boiling of both SFPs because the analysis assumed that only one SFP boiled. In addition, the staff identified the following aspects of the evaluation to be non-conservative during an audit on February 7, 1994: A) The SFP receiving cooling contributed significantly in the analysis to mitigating the effects of the boiling SFP. The significance of this effect was increased by the use of a lumped parameter model in the analysis and the use of a high heat transfer coefficient for condensation on the surface of the cooled pool. B) The volume of gas collected from the refueling floor atmosphere was significantly diluted and cooled by air flow from the remainder of the reactor building prior to entering the SGTS. The portion of the total inleakage flow from the refueling floor (one third of the total assumed in the analysis) is smaller than expected based on the construction of that portion of the reactor building and the area of the secondary containment boundary adjacent to the refueling floor. C) All entrained liquid droplets were removed from the air stream prior to entering the SGTS. Due to the absence of moisture removal devices in the recirculation plenum, substantial carryover of entrained liquid droplets would be expected.

The staff requests that PPKL provide an evaluation of SGTS operation for adesign basis seismic event with both SFPs boiling for an extended duration, justifying any deviation from the described design basis event. The licensee is also requested to justify use of the non-conservative assumptions identified above in the design basis evaluation of SGTS operation. Consistent with the licensing basis, the evaluation should consider the effects of humidity, temperature, and condensate collection on all portions of the SGTS. 2. The staff requests that PP&L provide an assessment of the capability of the emergency diesel generators to support the additional loading imposed by operating one loop of RHR in the SFP cooling assist mode and operating an alternate decay heat removal method described in procedure ON-l(2)49-001, "Loss-of RHR Shutdown Cooling," on the unit affected by operation of the RHR loop in the SFP cooling assist mode. The staff requests that the assessment bound all evaluated loss of SFP cooling events involving an extended loss of offsite power.

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