ML19208B416

Requests Submittal by 790924 of Procedures Implemented to Reduce Risk of ATWS Events During Interim Period Before Required Plant Mods as Determined by NRC Are Completed. Includes Operator Training Procedures for ATWS Events

ML19208B416
Person / Time
Site:	Sequoyah
Issue date:	08/17/1979
From:	Varga S Office of Nuclear Reactor Regulation
To:	Parris H TENNESSEE VALLEY AUTHORITY
References
FOIA-80-587, REF-GTECI-A-09, REF-GTECI-SY, TASK-A-09, TASK-A-9, TASK-OR NUDOCS 7909200236
Download: ML19208B416 (3)

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NUCLEAR REGULATORY COMM:SFION a

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E WASHINGTON, D. C. 2C5E4 k *.... p AUG 171979 Docket Nos.: 50-327/328 i

Mr. H. G. Parris Manager of Power Tennessee. Valley Authority 500A Chestnut Street Tower II Chattanooga, Tennessee 37401

SUBJECT:

INTERIM ACTIONS NEEDED FOR PLANT OPERATION PENDING-FINAL RESOLUTION OF ANTICIPATED TRANSIENTS WITH FAILURE TO SCRAM (ATWS)

(Sequoyah)

In December 1978 the Nuclear Regulatory Comission (NRC) staff issued Volune 3 of NUREG-0460 which describes the proposed type of plant modifications the staff believes are necessary to reduce the risk from anticipated transients with failure to scram (ATWS) to an acceptable level. The NRC's Regulatory Requirements Feview Comittee completed its review in January 1979, and concurrea with the staff's approach described in Volume 3 of NUREG-0460 insofar as it applies to Sequoyah.

The staff has issued requests for the industry to supply generic analyses to confirm the ATWS mitigation capability described in Volume 3 of NUREG-0460.

Subsequently, the staff plans to present its reccmendations for rulernaking.

on ATWS to the Comission. The Comissicn would, by rulemaking, detemine the required modifications to resolve ATWS concerns and the required schedule for the implementation of such modifications. Sequoyah would, of course, be subject to the Comission's decision in this matter.

Based on considerations described in pages 42 through 45, Volume 3 of NUREG-0460, the staff generally concluded that plants with opera;ing licenses can continae to operate without undue risk to the health and safety of the public during the estimated 2 to 5 year period needed to implement the necessary modifications.

However the staff believes the following steps should be taken as a prudert couru prior to the issuance of an operating license in order to further reJuce the risk from ATWS events during the interim period before the required plant modifications as detemined by the Comistica aru completed.

1.

Emergency procedures should be developed to train operatart to' recognize an ATWS event, including consideration of scran indicatcrs. cod position indicators, flux monitors, pressurizer level and pressure indicators,.

pressurizer relief valve and safety valve position indicators, coolant average temperature, containment temperature and pressure indicators, sten E generator level, pressure and flow indicators, and any other alams annu;ciatec in the control room including alams not processed through th( electrical portion of the reactor scram system. The emergency procedures sheuld be sufficiently simplified and unambiguous to pemit prompt AWS #4 cognition.

y/b lbb 7909200 J'yS W

Mr H. G. Parris ggg 17 7979 2.

The operator should be trained to take actions in the event of an ATWS including consideration of manually scramming the reactor by using the manual scram buttons, prompt actuation of the auxiliary feedwater system to assure delivery of the full capacity of this system, and initiation of turbine trip. These actions must be taken inmediately following the occurrence of the event. The operator should also be trained to promptly initiate boration by actuation of the high pressure safety injection system to bring the plant to a safe shutdown condition.

We require that you submit your procedures for our review. Please submit them by September 24, 1979. Our review will include a visit to your plant to detemine the feasibility of implementing your proposed procedures through operator simulation of the steps. Our evaluation must conclude that acceptable procedures and operator training are in place prior to the issuance of an operating licens.

Si ncerely,

_. m oa pSteven A. Vargs, Ac g Assistant Director for Ligh ater Reactors Division of Project Management cc: See next page e

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Tennessee \\ iiey Authority AUG 171979 ces:

Hecbert S. Sanger, Jr. Esq.

General Counsel Tennessee Valley Authority 400 Commerce Avenue EllB33 Knoxville, Tennessee 37902 Mr. E. G. Beasley Tennessee Valley Authority 400 Commerce Avenue W10Cl31 C Knoxville, Tennessee 37902 Mr. Michael Harding Westinghouse Electric Corporation P. O. Box 355-Pittsburgh, Pennsylvania 15230 Mr. David Lamoert Tennessee Valley Authority 400 Chestnut Street Tower II Chattanooga, Tennessee 37401 a 'ks;

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