ML18033A984

Informs of Plans to Implement Rev 4 to BWR Owners Group Emergency Procedures Guidelines Into Emergency Operating Instructions

ML18033A984
Person / Time
Site:	Browns Ferry
Issue date:	10/10/1989
From:	Michael Ray TENNESSEE VALLEY AUTHORITY
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
TAC-44285, NUDOCS 8910170347
Download: ML18033A984 (14)

Text

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ACCESSION NBR)8910170347 DOC.DATE: 89/10/10 NOTARIZED: NO DOCKET FACIL:50-260 Browns Ferry Nuclear Power Station, Unit 2, Tennessee 05000260 AUTH. NAME AUTHOR AFFILIATION RAY,M.J. Tennessee Valley Authority

,RECIP.NAME RECIPIENT AFFILIATION Document Control Branch (Document Control Desk)

SUBJECT:

Informs of plans to implement Rev 4 to BWR Owners Group R emergency procedures guidelines into instructions.

CODE'003D COPIES RECEIVED'LTR L ENCL L OR/Licensing Submittal: Suppl 1 to NUREG-0737(Generic Ltr 82-33) SIZE'ITLE:

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TOTAL NUMBER OF COPIES REQUIRED: LTTR 22 ENCL 21

0 TENNESSEE VALLEY AUTHORITY CHATTANOOGA. TENNESSEE 37401 5N 157B Lookout Place 00T 10 1999 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555 Gentlemen:

In the Matter of Docket No. 50-260 Tennessee Valley Authority BROWNS FERRY NUCLEAR PLANT (BFN) STATUS OF IMPLEMENTATION OF BWR OWNERS GROUP EMERGENCY PROCEDURES GUIDELINES REVISION 4 INTO BFN EMERGENCY OPERATING INSTRUCTIONS (TAC NO. 44285)

References:

1. NRC Safety Evaluation of "BWR Owners Group - Emergency Procedure Guidelines, Revision 4," dated September 12, 1988

2. NRC Inspection Report 88-200, dated September 28, 1988

3. Response to NRC Inspection Report 88-200, dated May 31, 1989

4. Letter from BWROG to USNRC (Mr. A. Thadani) dated September 18, 1989 (BWROG 8969)

The purpose of this letter is to inform NRC of TVA's plans to implement the BWR Owners Group (BWROG) Emergency Procedures Guidelines (EPGs) Revision 4 into the BFN Emergency Operating Instructions (EOIs).

The principal differences between Revision 3 and Revision 4 of the BWROG EPGs are presented in the staff's Safety Evaluation Report (Reference 1) and summarized below:

Revision 4 provides more detailed guidance to establish a containment vent initiation pressure.

Revision 4 addresses hydrogen control for Mark I containments.

Anticipated Transient Without Scram (ATWS) guidelines were revised in Revision 4. In Revision 3, reactor pressure vessel (RPV) water level was allowed to decrease only to the top of active fuel (TAF). It will be difficult to control reactor pressure vessel (RPV) water level exactly at TAF. In Revision 4, the EPGs are revised to give a range between TAF and minimum steam cooling RPV water level.

In Revision 4, the containment flooding contingency replaces the spray cooling contingency.

Revision 4 reduces the number of cautions to only seven.

Improved guidance is provided on venting, though it is acknowledged that the Commission is considering modifications as part of the Mark I program.

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I 00T 10 1S89 U.S. Nuclear Regulatory Commission The BFN EOIs are symptom based procedures for abnormal conditions of the plant. They are based on the NRC approved BNROG EPGs Revision 3 and have portions of Revision 4 incorporated. Reference 2 documents the NRC inspection of the BFN EOIs including simulator scenarios. NRC concluded that the BFN EOIs, when used by trained operators, can function adequately to mitigate the consequences of an accident. TVA replied to the inspection items in Reference 3 and committed to additional enhancements before the restart of Unit 2. Below is a summary of the status of the BFN EOIs in relation to the major items of BNROG EPGs Revision 4:

Containment Ventin Current BFN EOIs require venting at 55 psig drywell pressure regardless of other parameters. The basis for this action is to maintain operability of main steam relief valves. This was the limiting case from the review of the BNROG guidelines. This is in accordance with Revision 4. Loss of these valves seriously jeopardize the ability to adequately cool the core. A recalculation based on the capability of containment isolation valves to open against these pressures has been performed. TVA performed the required calculations per Revision 4. These calculations show that a change to the venting criteria will not be necessary.

Containment H dro en Control Current BFN EOIs require primary containment hydrogen monitoring; and nitrogen addition is required if hydrogen is indicated. This nitrogen is added by the containment atmospheric dilution system as instructed by a system operating instruction. Revision 4 requires a separate hydrogen control section for EOI-2. TVA is developing additional information for hydrogen control to be included in an abnormal operating instruction (AOI) which references EOI-2. This change is in accordance with the present BFN design basis. The change to the AOI will be accomplished prior to restart of Unit 2. Revision 4 requires venting and nitrogen addition at the same time, containment sprays, and emergency depressurization. These will not be included in the AOI but will be addressed in final Revision 4 implementation.

ATNS - Revision 4 allows the operator to lower level to between TAF and the minimum steam cooling RPV water level (below TAF). The existing BFN EOIs lowers level until 18 inches above TAF is reached. The widened RPV water level (Revision 4) control range is intended to provide operational flexibility while still assuring adequate core cooling. A concern has been identified by the Systems Branch of NRR on the relation of power oscillations and the further lowering (below TAF) of water level for ATNS events. An evaluation was performed for the BNROG and submitted to NRC by Reference 4 which indicated that existing ATNS actions are still adequate with the widened control range. TVA will implement the widened control band in conjunction with final implementation of Revision 4 of the EPGs into the BFN EOIs.

U.S. Nuclear Regulatory Commission Containment Floodin Revision 4 of the EPGs removed core cooling without level restoration (core spray) as a means of providing adequate core cooling and replaced this contingency -with primary containment flooding. Core cooling, without level restoration, is a contingency procedure entered only when reactor pressure is less than 100 psig and reactor level decreased to approximately the TAF and is continuing to decrease. This procedure is used under conditions where core submergence cannot be maintained, in cases such as large breaks and limited availability of other injection systems. This contingency was replaced with primary containment flooding which ensures core submergence. This would be an extremely unlikely event and no plans presently exist to implement this contingency prior to startup. However, BFN EOIs do provide for alternate injection systems (including those from outside primary containment). These alternate injection systems are used before core cooling without level restoration, and in combination with the BFN EOI-2 Suppression Pool Level Procedure, would either ensure core submergence without containment flooding, or would flood containment to 108 ft. which is 21 ft. above the top of the core (el. 608). Flooding beyond 108 ft. is prohibited to allow the continued capability of venting containment and preclude the release of large amounts of radioactive water through the vents. The only major changes that would occur when Revision 4 is adopted are actions to vent both reactor vessel and primary containment. These actions would affect present design bases for some events and require further evaluation.

Cautions TVA has implemented all the applicable cautions in the BFN EOIs in accordance with BWROG EPGs Revision 4, Containment Ventin (Hardened Vent) The calculations associated with containment venting are discussed above. The Commission on September 1, 1989 issued guidance for Hark I containments in this area under Generic Letter 89-16: Installation of Hardened Wetwell Vent. TVA is performing the analysis to provide the required response to the generic letter.

Both Revision 3 and Revision 4 of the EPGs contained an alternate means of injecting boron following a failure to scram. This is used if the standby liquid control system does not operate. This contingency is very plant specific. BFN does not presently have a method of accomplishing this task, but different alternatives are being pursued and TVA will have a method in place prior to Unit 2 restart.

The BFN EOIs are not currently in a flowchart format. In addition, the BWROG EPGs Revision 4 do not require a flowchart format. BFN personnel have evaluated the use of flowcharts and do not intend 'to use them at this time.

Based on current industry information, NRC inspections have noted problems with the development and use of these flowcharts. TVA believes that flowcharts are not needed to support Unit 2 restart based on the symptom based procedures currently in place along with the unique layout of our procedures and training BFN operators have and continue to receive on the EOIs. TVA will continue to evaluate the use and need of flowcharts.

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OT 10 1%8 U.S. Nuclear Regulatory Commission TVA shares the staff's view that Revision 4 of the EPGs is an improvement over earlier versions of the EPGs. In the response to NRC Inspection Report 88-200, TVA committed to implement Revision 4 in 1990 at BFN. This commitment was made after a careful assessment of the time required to write the new EOIs and the necessary classroom and simulator time to train BFN operators before implementing the change. Our available simulator and classroom training time are being fully utilized to train BFN operations personnel on startup procedures and scenarios in preparation for Unit 2 restart. Although TVA is pursuing the preparation of the Revision 4 procedures in an expeditious manner, it is TVA's intention to minimize the changes to procedures during the restart period and maximize the use of the plant and simulator to reinforce the knowledge of existing procedures. TVA anticipates the BNROG EPGs Revision 4 to be incorporated into the BFN EOIs near the Unit 2 restart date. After completion of startup/power ascension activities, TVA will perform the necessary retraining of operations personnel to complete the implementation of BHROG EPGs Revision 4 into the BFN EOIs.

The enclosure lists the commitments contained in this letter.

If you have any questions, please telephone Patrick P. Carier at (205) 729-3570.

Very truly yours, TENNESSEE VALLEY AUTHORITY Manager, Nucl ar Licensing and Regulatory Affairs Enclosure cc: See page 5

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OGT 10 1889 U.S. Nuclear Regulatory Commission cc (Enclosure):

Hs. S. C. Black, Assistant Director for Projects TVA Projects Division U.S. Nuclear Regulatory Commission One White Flint, North 11555 Rockville Pike Rockville, Maryland 20852 Mr. B. A. Wilson, Assistant Director for Inspection Programs TVA Projects Divis)on U.S. Nuclear Regulatory Commission Region II 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323 NRC Resident Inspector Browns Ferry Nuclear Plant Route 12, Box 637 Athens, Alabama 35609-2000

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Enclosure Browns Ferry Nuclear Plant Emergency Operating Instructions Commitments Contained In Letter

l. TVA is developing additional information for hydrogen control to be included in an abnormal operating instruction (AOI) which references EOI-2. This change is in accordance with the present BFN des,ign basis. The change to the AOI will be accomplished prior to restart of Unit 2".

2. BFN does not presently have an alternate means of injecting boron following a failure to scram, but different alternatives are being pursued and TVA will have a method in place prior to Unit 2 restart.

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