ML20059M660

Forwards Revised Task Action Plan for Evaluation of Loss of SFP Cooling Events & Estimate of Staff Resources Required to Complete Action Plan Tasks

ML20059M660
Person / Time
Site:	Susquehanna
Issue date:	11/15/1993
From:	Varga S Office of Nuclear Reactor Regulation
To:	Callan L Office of Nuclear Reactor Regulation
Shared Package
ML17158A025	List: ML20059M660
References
NUDOCS 9311190218
Download: ML20059M660 (7)

Text

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ENCLOSURE

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M 0, l k UNITED STATES i ( Li,' '[ f NUCLEAR REGULATORY COMMISSION

%, - 1 j w Asmucion. o c. :osss-oooi i November 15, 1993 MEMORANDUM FOR: Leonard J. Callan Acting Associate Director for Projects Office of Nuclear Reactor Regulation William T. Russell i Associate Director for Inspection and Technical Assessment  !

Office of Nuclear Reactor Regulation FROM: Steven A. Varga, Director Division of Reactor Projects - I/II Office of Nuclear Reactor Regulation Ashok C. Thadani, Director -

Division of Systems Safety and Analysis Office of Nuclear Reactor Regulation

SUBJECT:

RE'llSED TASK ACTION PLAN FOR EVALUATION OF LOSS OF SPENT FUEL P0OL COOLING EVENTS On October 29, 1993, the staff issued a task action plan for evaluation and resolution of technical issues related to postulated loss of spent fuel pool cooling events. After consider 4 tion of early technical findings and clarification of the work score necessary to characterize the risk associated with the loss of normal spent fuel cooling, the staff has revised the action plan and accelerated the schedule for certain tasks. The revised action plan is included as Enclosure 1.

On November 27, 1992, a 10 CFR Part 21 notification was filed to notify the NRC of pottntial weaknesses in the design of SFP cooling systems at Susquehanna steam Electric Station (SSES). The notification stated that a lass-of-coolant accident (LOCA) could create an inability to adequately cool the SFP. The loss of SFP cooling is assumed to result from piping failure in the SFP cooling or the service water system cooling the SFP heat exchangers caused by LOCA-induced hydrodynamic effects, or from a long-term loss of offsite power (LOOP) coincident with the LOCA. The effects of the LOCA are assumed to prevent necessary access to the reactor building for restoration of a method of SFP decay heat removal. Subsequent boiling of the SFP is assum d to cause failure of equipment necessary for accident mitigation due to the environmental conditions caused by SFP boiling within the reactor building.

Based on these equipment failures, severe offsite consequences are assumed to resul t .

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CON 1AC1:

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. 1 The concerns regarding the design of SFP cooling systems that were identified in the 10 CFR Part 21 notification may have generic implications. The .

concerns appear to be relevant to boiling water reactors (BWRs) with Mark I '

and Mark 11 containment designs due to the location of the SFP within the J reactor building. However, certain concerns may be applicable to BWRs with Mark III containments and pressurized water reactors (PWRs), which have separate fuel handling buildings. This task action plan (Enclosure 1) is intended to focus NRC staff actions to (1) determine the safety significance of the identified concerns, (2) determine the facilities where the concerns are applicable, (3) evaluate the adequacy of present spent fuel pool cooling ,

system designs, and (4) evaluate adequacy of current NRC guidance for SFP cooling system design. Enclosure 2 is an estimate of staff resources required to complete the action plan tasks.

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Ashok C. Thadani, Director

d. M Steven A. Va. ga, D ec or Division of Systems Safety and Analysis Division of Reacto' rojects - I/II ,

Office of Nuclear Reactor Regulation Office of Nuclear Re ctor Regulation f Enciosures:

1. Revised Spent Fuel Pool Task Action Plan

2. Staff Resource Estimate cc w/ enclosures:

T. Murley ,

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SPENT FUEL POOL TASK ACTION PLAN. REVISION 1 ENCLOSL'RE 1 I TASK TASK: LC (EVALUATION OF SCENARIOS RESPONSIBLE DUE ITEM PRESENTED IN 10 CFR PART 21 ORGANIZATION DATE STATUS.

• NO. REPORT)

LC-1 Conduct inspection of SSES to review licensee DSSA/SCSB 10/20/93 Compl.

hydrodynamic and piping load information in DE/EMEB thru detail. 10/22/93 LC-2 Review 10 CFR Part 21 report and subsequent DRPE/PDI-2 11/12/93 .

correspondence. Identify all scenarios and  !

related technical issues.

LC-3 Evaluate the capability of the SFP cooling DSSA/SPLB 01/21/94 i i and water make-up systems to provide adequate  ;

cooling to the SFP during all anticipated '

operating and accident conditions. The review will include the following considerations:

(1) the potential for failure of safety-related equipment due to the effects of spent fuel pool boiling (2) the time available for performance of mitigating actions prior to the onset of spent fuel pool boiling ,

(3) the rate of water loss during spent fuel pool boiling  ;

(4) the availability of alternate spent  ;

fuel pool cooling methods (5) the availability of adequate spent I fuel pool makeup water ,

(6) the availability and capacity of the ultimate heat sink (7) the adequacy of instrumentation to monitor spent fuel pool conditions (8) the ability of the reactor building ventilation and drainage systems to accommodate the water vapor and condensation resulting from a boiling '

spent fuel pool (9) the potential for failure of spent fuel pool cooling systems due to post-LOCA environmental conditions ,

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t TASK TASK: LC (EVALUATION OF SCENARIOS RESPONSIBLE 00E t ITEM PRESENTED IN 10 CFR PART 21 ORGANIZATION DATE STATUS f10. REPORT)  ;

LC-4 Evaluate the data from the SSES inspection DE/EMEB 12/15/93 and determine susceptibility of the spent DSSA/SCSB  !

fuel pool cooling system piping and the plant t service water system piping to failure as a  !

result of LOCA-induced hydrodynamic or seismic stresses. Provide results to Plant Systems Branch and the Risk Assessment Branch. l LC-5 Determine the accessibility of the reactor DRSS/PRPB 12/10/93 building under post-LOCA conditions for performance of the manual valve manipulations  ;

required to align the residual heat removal  !

system and essential service water system for  ;

spent fuel pool cooling and spent fuel pool  !

makeup water, respectively. Provide results to Plant Systems Branch. ,

LC-6 Evaluate the adequacy of the plant procedures DRCH/HHFB 01/21/94 l and training to support the alignment of the i residual heat removal system and essential  ;

service water system for spent fuel pool l cooling and spent fuel pool makeup water, respectively. Provide results to Plant j Systems Branch. .

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LC-7 Perform risk Tssessment of loss of spent fuel DSSA/SPSB 02/18/94 pool cooling scenarios associated with LOCA initiating events (including LOCA/ LOOP). I consider results of tasks LC-3 through LC-6. l Technical assistance support is required.

f LC-8 Write Safety Evaluation of SSES Spent Fuel DSSA/SPLB 02/25/94 I

Pool Cooling System Susceptibility to scenarios identified in Part 21 Report. '

Provide to ORPE/PDI-2.

. LC-9 Determine SSES licensing basis for loss of OP.PE/PDI-2 12/01/93 spent fuel pool cooling requirements.

LC-10 Evaluate SSES SFP cooling configuration DSSA/SPLB 01/21/94 against licensing basis requirements ,

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TASK RESPONSIBLE DUE ITEM TASK: COM (COMMUNICATION PLAN) ORGANIZATION DATE STATUS N0.

COM-1 issue Information Notice 93-83 00RS/0GCB 10/07/93 Compl.

COM-2 Communications with Lochbaum and Prevatte DRPE/PDI-2 Contin.

(Lead)

COM-2a Provide Copy of Action Plan to L&P DRPE/PDI-2 11/19/93 COM-2b Provide periodic status update DRPE/PDI-2 Periodic COM-2c Provide copies of all external correspondence DRPE/PDI-2 Contin.

regarding staff action on loss of spent fuel pool cooling evaluation. 03/11/94 i COM-2d Provide copies of staff safety evaluation DRPE/PDI-2 03/15/94 COM-3 Provide briefings to Representative Lehman DSSA & PDI-2 11/05/93 Compl. l staff l

COM-3a Provide briefings to additional congressional DSSA & PDI-2 TBD inquiries COM-4 Prepare letter for Commission describing DSSA & PDI-2 11/25/94 action plan i COM-5 Prepare formal response to public inquiries DRPE/PDI-2 As concerning SSES or generic action Required l

l COM-6 Issue Generic Communications as necessary DORS /0GCB TBD {

based on outcome of action GA-4 1

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TASK RESPONSIBLE DUE '

ITEM TASK GA (GENERIC APPLICABILITY) ORGANIZATION DATE STATUS NO.  ;

GA-1 Conduct initial screen of BWR for scenario DRPE/PDI-2 10/22/93 Comp 1.

applicability. Develop screen criteria in -

conjunction with DSSA/DE. Provide screen s results to DSSA.

GA-2 Conduct initial review of historical and D.'*/SPLB 10/22/93 Compl.

current regulatory requirements.

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GA-3 Conduct initial screen of PWRs for scenario DRPE/PDI-2 10/22/93 Comp 1.

applicability. Develop screen criteria in conjunction with DSSA/DE. Provide screen results to OSSA 1 GA-4 Evaluate need for generic communication for DSSA/SPLB 01/07/94

• information collection. Commence generic r communication development if required. {

GA-5 Develop options for resolution of spent fuel DSSA/SPLB TBD f

pool cooling issues, including issuance of additional Generic Communications, i development of a proposed rule, or  !

documentation of the acceptability of the  !

existing regulatory basis for spent fuel pool cooling and support systems.

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ENCLOSURE 2 i i

STAFF RESOURCE ESTIMATE  !

The following resources requirements are estimated for the completion of the action items in '

Enclosure 1. The estimates do not include estimates for contractor resources. The need for l contract resources will be evaluated as relevant branches perform the assigned tasks. i STAFF DIVISION BRANCH RESOURCE ESTIMATE

-l DRCH Human Factors Branch (HHFB) 120 staff-hours .

DSSA Risk Assessment Branch (SPSB) 160 staff-hours and $80.000 for technical assistance support '

DSSA Plant Systems Branch (SPLB) 400 staff-hours .

DSSA Containment System Branch 80 staff-hours  !

(SCSB)

DE Mechanical Engineering Branch 120 staff-hours (EMEB) l DRPE Project Directorate I-2 450 staff-hours (PDI-2) .

DORS Generic Communications Branch- TBD (0GCB)

DRSS Radiation Protection Branch 120 staff-hours (PRPB)- l t

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