ML17158A300

Requests Addl Info Re Util Capability to Mitigate,In Manner Consistent W/Licensing Basis of Plant,Effects of Loss of SFP Cooling Initiated by Design Basis Seismic Event

ML17158A300
Person / Time
Site:	Susquehanna
Issue date:	05/19/1994
From:	Chris Miller Office of Nuclear Reactor Regulation
To:	Byram R PENNSYLVANIA POWER & LIGHT CO.
References
GL-91-18, TAC-M85337, NUDOCS 9405310051
Download: ML17158A300 (7)

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Docket Nos. 50-387 and 50-388 UNITED STATES NUCI EAR REGULATORY COMMISSION WASHINGTON, D.C. 2055&4001 May 19, 1994 Hr. Robert G.

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

SUBJECT:

REQUEST FOR ADDITIONAL INFORMATION (RAI) CONCERNING LOSS OF SPENT FUEL POOL COOLING INITIATED BY THE DESIGN BASIS SEISMIC EVENT, SUSQUEHANNA STEAM ELECTRIC STATION, UNITS 1

AND 2 (TAC NO. H85337)

The purpose of this letter is to request additional information regarding Pennsylvania Power

& Light Company's (PP&L's) capability to mitigate, in a manner consistent with the licensing basis of Susquehanna Steam Electric Station (SSES),

the effects of a loss of spent fuel pool (SFP) cooling initiated by the design basis seismic event.

Recent PP&L responses to requests for additional information have not satisfactorily resolved this concern.

As a result of a licensing basis review, the NRC staff concluded that acceptance during original licensing of SSES of a SFP cooling loop not qualified to seismic Category I standards was based on the provision of a standby gas treatment system (SGTS) qualified to =seismic Category I standards and capable of operating under the conditions resulting from the postulated design basis accident (DBA).

Unless SFP cooling is promptly restored using a

system qualified to seismic Category I standards, the conditions resulting from a design basis seismic event with a loss of offsite power (LOOP) include those associated with a boiling SFP.

PP8L performed

analyses, which were reviewed by the NRC staff during an audit at PP&L headquarters on February 7,

1994, evaluating the effects of a single boiling SFP coincident with a loss of coolant accident on the SGTS.

These analyses indicated that the SGTS at SSES will be degraded and eventually rendered inoperable by the conditions resulting from a boiling SFP.

Subsequently, PP8L submitted a letter dated May 4, 1994, which documented the results of a similar analysis that assumed both SFPs boil following a design basis seismic event.

These results indicate that degradation of the SGTS due to excessive accumulation of condensate could begin as early as 17 hours1.967593e-4 days <br />0.00472 hours <br />2.810847e-5 weeks <br />6.4685e-6 months <br /> following the onset of boiling.

A separate PP&L evaluation indicates that SFP cooling capability is inadequate to prevent SFP boiling following a design basis seismic event with a LOOP.

PP8L provided the results of this evaluation in a letter dated Hay 5, 1994.

One evaluated configuration assumed that both units were initially at power A

and that no free communication existed between the SFPs.

As a result of this

analysis, which assumed the design basis seismic event, a

LOOP, and a single failure affecting the SFP cooling mode of the residual heat removal

system,

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Hr. Robert G.

Byram May 19, 1994 1

Elsewhere in the Hay 5, 1994, letter, PP&L committed to complete a procedure change to assist in mitigating the effects of a 'boiling SFP.

If a loss of spent fuel pool cooling occurs, SFP cooling cannot be restored, and no source term is present, this proposed procedure change specifies venting the refueling floor directly to atmosphere.

The Hay 5, 1994, letter specifically identifies a seismic event as an instance where this procedure change may be implemented.

Although the NRC staff recognizes that direct venting of the refueling floor to atmosphere is unlikely to cause offsite doses to exceed 10 CFR Part 100 site evaluation criteria and the action is consistent with the current design and operation of SSES, the proposed action is clearly not consistent with the basis for staff acceptance of a SFP cooling system not qualified to seismic Category I standards during licensing.

NRC staff acceptance was based on a

filtered release from the boiling SFP.

The NRC staff has also identified that Appendix 9A of the SSES Final Safety Analysis Report, which contains PP&L's analysis for the design basis seismic event, states that the SFPs will be operated in a manner that ensures the SFPs will not boil until at least 25 hours2.893519e-4 days <br />0.00694 hours <br />4.133598e-5 weeks <br />9.5125e-6 months <br /> following a loss of cooling.

However, no administrative controls are in place with regard to control of the time to the onset of boiling.

Clearly, a

discrepancy exists between the SSES licensing basis with regard to spent fuel pool cooling following a design basis seismic event and the current design and operation of SSES.

Generic Letter 91-18, "Information to Licensees Regarding Two NRC Inspection Manual Sections on Resolution of Degraded and Non-Conforming Conditions and On Operability," provides guidance for resolution of degraded or non-conforming conditions.

The NRC staff recognizes that resolution of the discrepancies identified above may involve changes to design or procedural guidance at SSES.

The staff requests that you identify your course of action with regard to the above discrepancy.

Your response to the above items is requested by Hay 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, please contact me at (301) 504-1428.

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Byram May 19, 1994 Elsewhere in the Hay 5, 1994, letter, PPIlL committed to complete a procedure change to assist in mitigating the effects of a boiling SFP.

If a loss of spent fuel pool cooling occurs, SFP cooling cannot be restored, and no source term is present, this proposed procedure change specifies venting the refueling floor directly to atmosphere.

The Hay 5, 1994, letter specifically identifies a seismic event as an instance where this procedure change may be implemented.

Although the NRC staff recognizes that direct venting of the refueling floor to atmosphere is unlikely to cause offsite doses to exceed 10 CFR Part 100 site evaluation criteria and the action is consistent with the current design and operation of SSES, the proposed action is clearly not consistent with the basis for staff acceptance of a SFP cooling system not qualified to seismic Category I standards during licensing.

NRC staff acceptance was based on a

filtered release from the boiling SFP.

The NRC staff has also identified that Appendix 9A of the SSES Final Safety Analysis Report, which contains PPSL's analysis for the design basis seismic event, states that the SFPs will be operated in a manner that ensures the SFPs will not boil until at least 25 hours2.893519e-4 days <br />0.00694 hours <br />4.133598e-5 weeks <br />9.5125e-6 months <br /> following a loss of cooling.

However, no administrative controls are in place with regard to control of the time to the onset of boiling.

Clearly, a

discrepancy exists between the SSES licensing basis with regard to spent fuel pool cooling following a design basis seismic event-and the current design and operation of SSES.

Generic Letter 91-18, "Information to Licensees Regarding Two NRC Inspection Manual Sections on Resolution of Degraded and Non-Conforming Conditions and On Operability," provides guidance for resolution of degraded or non-conforming conditions.

The NRC staff recognizes that resolution of the discrepancies identified above may involve changes to design or procedural guidance at SSES.

The staff requests that you identify your course of action

'with regard to the above discrepancy.

Your response to the above items is requested by Hay 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, please contact me at (301) 504-1428.

Sincerely,~ Pwm Charles L. Miller, Director Project Directorate I-2 Division of Reactor Projects - I/II Office of Nuclear Reactor Regulation cc:

See next page

4

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Mr. Robert G.

Byram Pennsylvania Power

& Light Company Susquehanna Steam Electric Station, Units 1

& 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

& Light Company 2 North Ninth Street Allentown, Pennsylvania 18101 Mr. J.

M. Kenny Licensing Group Supervisor Pennsylvania Power

& 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. William P. Dornsife, Director Bureau of Radiation Protection Pennsylvania Department of Environmental Resources P. 0.

Box 8469 Harrisburg, Pennsylvania 17105-8469 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 Vice President-Nuclear Operations 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 Vice President-Nuclear Engineering Pennsylvania Power and Light Company 2 North Ninth Street Allentown, Pennsylvania 18101