ML19317F638

Confirms Discussion W/Util That Instrumentation Ground Grid Sys at Facility Acceptable for Power Operation in Mode 1. Conclusions Based on SER & Util Commitment to Monitor Instrumentation Sys

ML19317F638
Person / Time
Site:	Davis Besse
Issue date:	09/26/1977
From:	Vassallo D Office of Nuclear Reactor Regulation
To:	Roe L TOLEDO EDISON CO.
References
TAC-10996, NUDOCS 8001220923
Download: ML19317F638 (3)

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Docket Fi R. Vollmer NRC PDR M. Ernst Local POR W. Gammill SEP 2 6 IT7 LWR 1 File K. Seyfrit R. Boyd ELD R. DeYoung IE (3)

Docket No. 50-346 D. B. Vassallo F. J. Williams bec: J. R. Buchanan, J. Stolz NSIC Toledo Edison Company L. Engle T. B. Abernathy, ATTN: Mr. Lowell E. Roe E. Hylton TIC Vice President Facilities R. Mattson ACRS (16)

Development D. Ross-EJison Plaza J. P. Knight 300 Madison Avenue R. Tedesco Toledo, Ohio 43652 H. Denton V. Moore Gentlemen:

SUBJECT:

INSTRUMENT-STATION GROUND GRID SYSTEM - DAVIS-BESSE UNIT 1 (REF: TOLEDO EDIS0N CDMPANY LETTERS FROM L. ROE TO D. VASSALLO DATED AUGUST 30, 1977 AND SEPTEMBER 16,1977)

This letter will confim the discussions held between D. Vassallo and L. Roe during which we concluded that the presently installed instrument-station ground grid system at Davis-Besse, Unit 1 is acceptai,.e for Davis-Besse 1 proceeding to facility power operation in Mode 1 based on our review of your safety evaluation and comitments in your referenced i

letters.

Our conclusion is based on our safety evaluation and your comitments listed below:

(1) The Davis-Besse, Unit 1 instrumentation systems have functioned properly with no abnormalities encountered during the pre-operational testing period and for four months following fuel loading, testing, criticality, and zero power testing.

1 (2) No inadvertent ties have been identified between the Safety Features Actuation System instrument ground and the station ground and therefore, one cannot postulate station electrical faults that will adversely affect the engineered safety features of the facility.

i (3) Your analysis presented at the August 25, 1977 meeting,and subse-quently documented in your letters referenced above, for the effect j

of ground currents introduced into the station grounding grid 1

from the worst possible postulated station electrical fault condition with the inadvertent ties between the present instrument and station ground systems showed that safety systems will still y.A perfom as intended.

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(4) You will continue to analyze and test the instrumentation systems to identify and eliminate any inadvertent ties between the instrinnent and station ground grid and will provide to the NRC by no later than the end of the first scheduled refueling outage the results of your analysis, testing and corrective actions that have been implemented to assure ' hat the installation meets the design criteria.

(5) You will carefully monitor the instrumentation systems for any spurious operations and degrading conditions requiring corrections. Normal instrumentation monitoring will meet the definitions of a channel check (every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />),

channel functional test (every 30 days), and daily heat balance check will be conducted as specified in the facility technical specifications for instrumentation systems. Also, l

you will maintain a record of your monitoring of these systems and will report in a timely manner any abnormalities to NRC (Inspection & Enforcement, Region 3).

Based on items 1, 2, and 3 above and the comitments made by the Toledo Edison Company in items 4 and 5 above, we conclude that the likelihood of any degrading conditions on safety related instrumentation due to the presence of any remaining cross-connections between the instrument and stat 1on ground that could adversely affect the health and safety of the public during operation of Davis-Besse, Unit 1 in Mode 1 is acceptably small.

Sincerely, G

D. B. Vassallo, Assistant Director for Light Water Reactors Division of Project Management cc: See Page 3 l

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Tbledo Edison Company 3-SEP 2 6 1977 cc: Donald H. Hauser Esq.

The Cleveland Electric Illuminating Company P. O. Box 5000 Cleveland, Ohio 44101 Gerald Charnoff, Esq.

Shaw, Pittman, Potts & Trowbridge 1800 M Street, N. W.

Washington, D. C.

20036 Leslie Henry, Esq.

Fuller, Seney, Henry and Hodge 300 Madison Avenue Toledo, Ohio 43604 i

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