ML20147D619

Responds to Items Discussed in 871207 Telcon Re Mods to ATWS Protection Sys Described in Util

ML20147D619
Person / Time
Site:	Zion  File:ZionSolutions icon.png
Issue date:	02/26/1988
From:	Trzyna G COMMONWEALTH EDISON CO.
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
4237K, NUDOCS 8803040072
Download: ML20147D619 (3)

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Commonwealth Edison f One First N';:ional Plaza, CNeago, Illinois e

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v 4 /) Add60690 0767 ress Reply to: Post Omce Box 767 February 26, 1988 U.S. Nucle'ar Regulatory Commission Washington / DC. 20555 Attn: Document Control Desk

Subject:

Zion Nuclear Power Station Units 1 and 2 .

l AWS Protection-10CFR 50.62 NRC Docket Nos. 50-295 and 50-304

References:

(a) January 9, 1987 letter from P.C. LeBlond to H.R. Denton (b) July 21, 1987 letter from P.C. LeBlond to US. NRC Gentlemen: .

A description of the proposed modification for Zion Station of the ,

ATWS protection system in accordance with 10CFR 50.62 requirements was originally described in a June 5, 1986 letter from P.C. LeBlond to H.R.

Denton. References (a) and (b) provided supplementary information in response to NRC concerns. This submittal provides a response to items that were discussed in a December 7, 1987 conference call between representatives from NRR and Commonwea1th Edison.

Commonwealth Edison's response to the specific concerns resulting from the December 7, 1987 conference call are addressed below:

1) Diverse Relays Commor. wealth Edison has decided that the Potter and Brumfield MDR series relay will be used for AWS applications rather than than NBFD-type relay which is used in the present reactor protection system.

2) A WS Armed Annunciator and Arming Setpoint A permissive annunciator light will be pro % which will operate as follows: (a) light is lit when AWS is not armed, ie, reactor power below 40%; (b) light is out when AWS is armed, ie, reactor power greater than 40%.

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- 3) A'NS Annunciators commonwealth Edison has reviewed the proposed modification and has concluded that separate annunciators will be used to indicate status of ATWS instrumentation. One. annunciator will operate as described in No.

2 above, and a separate annunciatorcwill be used to indicate when then ATWS system is in a "Test" mode.

The following issue is one of recent origin and was not discussed in the December 7, 1987 conference call.

4) Request to Change Isolation Device for ATVS  !

The correspondence indicated in Reference (b) previously transmitted the design of the proposed modification. This letter indicated that the W 7300 series isolators would be employed in the design. -

Commonwealth Edison's engineering department has reevaluated the proposed design and has recommended.that W?l00 series isolators be used instead of the M7300 series. This recommendation is based on the following justifications:

a) The V7300 series isolator cabinet is located about 40 ft away from the reactor protection cabinet. It would be necessary i to extend the current loop approximately 40 ft. to utilize the V7300 cabinet hardware. Ceco engineering recommends that the current loop be maintained as compact as possible to minimize adverse interferences. 3 1

b) The use of the V7100 series isolators would allow the ATWS circuitry to be installed in the reactor protection cabinet i in order to limit the size of the current loop.

1 Additionally, the M7100 isolator located in the reactor I l

protection cabinet would be dedicated entirely to ATWS

' circuitry to preclude interferences from other plant systems.

c) The V7100 series isolator has proven to be very reliable over l

the past 15 years at Zion Station. Even if it were to fail, the failure would be in the same conservative mode as the W7300 isolator.  !

l Schedules for implementation of the ATWS Mitigation System were not l discussed in the December 7, 1987 telephone conversation. In light of the recent changes in the proposed modification discussed above and the requirement for integrated outage planning, the following dates are the proposed implementation schedules:

Unit 1-Summer 1989 refueling outage Unit 2-Spring 1990 refueling outage i,

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Please direct any further questions regarding this matter to this office.

Very truly yours,

.J .

G. E. Trzyna Nuclear Licensing Administrator

/klj cc: Zion Resident Inspector J.A. Norris-NRR 4237K i

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