ML20054H372

Forwards Page 4 of Encl 2 Inadvertently Omitted from Re Independence of Reactor Protection Sys

ML20054H372
Person / Time
Site:	Maine Yankee
Issue date:	06/14/1982
From:	Nelson C Office of Nuclear Reactor Regulation
To:	Garrity J Maine Yankee
References
NUDOCS 8206230324
Download: ML20054H372 (3)

Text

m g

Yw 7

. \\>oc-< ret 3 c5 T'\\S-0 4 JUN 141982 Distribution:

2 DocketNo.50-h09 Docket File NRC PDR Local PDR ORB #3 Rdg DEisenhut JHel temes Mr. John H. Garrity, Senior Director PKreutzer Nuclear Engineering and Licensing CNel son Maine Yankee Atomic Power Company MConner 83 Edison Drive Augusta, Maine 04336 E O)

NSIC

Dear Mr. Garrity:

ACRS (10)

It has come to our attention that Page 4 of Enclosure 2 was inadvertently omitted from our March 31, 1982 letter regarding the independence of the Reactor Protection System. Since this page could affect your future actions on this subject, it is enclosed with this letter.

Please accept our Apo for any inconvenience this oversi~ght .as caused you.

\\ t'Or /, q, n8c

-1 Sincerely, h :.s I[if x

orignat e'@d

y@ ~

(

2-Oh! Q

[:

Christian Nelson, Project Manager f' g; -

/y Operating Reactors Branch #3 fz f'

/g's u

\\

Division of Licensing

• ~

O s

Enclosure:

/c As stated I

cc w/ encl:

See next page l

l l

I l

l l

8206230324 820614 PDR ADOCK 05000309 P

pgp DL:0RB#3 DL:0RB#3 DL:0RB#3 g[.RB#3

.. %....j[. 15dia7E" FKreutzer Cr.

n. s EL I

runuue >..g.....j......

.j....j.g.j...h.......

j

... 7..j........F...............

ons>

nac ronu ais oow nacu o24o OFFICIAL RECORD COPY usam i_m-m

1 Maine Yankee Atomic Power Com,pany4.,

E. W. Thurlow President Judith M. Barrows, Presid;nt cc:

Maine Yankee Atomic Power Company SAFE POWER FOR MAINE Edison Drive Post Office Box 2204.

_~

Augusta, Maine 04336 Augusta, Maine 04330 Mr. Donald E. Vandenburgh First Selectman of Wiscasset Vice President - Engineering Municipal Building Yankee Atomic Electric Company U. S. Route 1 20 Turnpike Road Wiseasset, Maine 04578 Westboro, Massachusetts 01581 John A. Ritsher, Esquire Atomic Safety and Licensing Board Ropes & Gray U.S. Nuclear Regulatory Commission 225 Franklin Street Washington, D. C.

20555 Boston, Massachusetts 02110 David Santee Miller, Esq.

Mr. Rufus E. Brown 213 Morgan Street, N. W.

Deputy Attorney General Washington, D. C.

20001 State of Maine Augusta, Maine 04330 Mr. Paul Swetland Resident Inspector / Maine Yankee Mr. Nicholas Barth c/o U.S.N.R.C.

Executive Director P. 0.> Box E Sheepscot Valley Conservation Wiscasset, Maine 04578 Association, Inc.

P. O. Box 125 Mr. Charles B. Brinkman

~

Alan, Maine 04535 Manager - Washington Nuclear Operations Combustion Engineering Inc.

Wiscasset Public Library Association 4853 Cordell Avenue, Suite A-1 High Street Bethesda, Maryland 20014 Wiscasset, Maine 04578 Mr. Robert H. Groce Mr. Torlet H. Macdonald, Jr.

Senior Errgineer - Licensing Of fice of Energy Resources Maine Yankee Atomic Power ' Company State H6use Station #53 1671 Worcester Road Augusta, Maine 04333 Framingham, Massachusetts 01701 Robert M. Lazo, Esq., Chairman

' Atomic Safety and Licensing Board U.S. Environmental Protection Agency U.S. Nuclear Regulatory Commission Region I Office Washington, D. C.

20555 ATTN:

Regional Radiation Representative JFK Federal Building Dr. Cadet H. Hand, Jr., Director Boston, Massachusetts 02203 Bodega Marine Laboratory University of California Bodega Bay, California 94923 Mr..E. C. Wood, Plant Manager y

Maine Yankee Atomic Power Company State Planning Officer P. O. Box 3270 Executive Department Wiscasset, Maine 04578 189 State Street Augusta, Maine 04330 Regional Administrator Nuclear Regulatory Commission, Region I Office of Executive Director for Operations 631 Park Avenue Kini; of Prussia, Pennsylvania 19406

s.

m

~

e) Acceptance criteria for perturbations which vi:uld be allowed within the redundant vital bus without interfering with any protection system actions, f) Justification that the faults and surges used during the

~

testing exceed the maximum worst-case failures which could occur within the protection systems circuits.

5.

Locic Matrix Circuitry Failure Due to a Vital Bus Sinole Failure Each plant must be reviewed to assure that, with a channel in bypass, a single failure of a vital bus will not prevent the

' protection system from performis g its protective function.

As stated in item 4 above, the CE reactor protection system forms six logic matricies (AB, AC, AD, BC, BD and CD) from all possible coincidences of two combinations of the four protection channel

. bistables and associated contacts.

Due to the vital bus arrange-6ment a single failure of a vital bus coincident with the bypass of a channel could prevent the required protective function of the RPS.

Looking at figuN1, assume that a channel A trip parameter is bypassed.

This results in negating the AB, AC and AD logic l

matricies protecti've functions.

This now leaves the BC, BD, and CD logic matricies for protection.

However, as shown in figure 1, these remaining matricies are being supplied by a corrrnon vital bus.

It can now be postulated that a. single failure (fault, surge, etc.) within the common vital bus system might propogate through the logic matrix power supplies into the matrix circuitry. This could thereby cause a failure (welding of contacts) of the remaining logic matricies such that the required protective function cannot be per-

. _,, _, _ - _ _. _. -.