ML20245J260

Provides Addl Info Re Proposed Amend to Tech Specs Section 3.15, Auxiliary Electric Power Sys. Info Answers & Resolves Questions Raised by NRC Re Tech Spec Amend Request

ML20245J260
Person / Time
Site:	Zion  File:ZionSolutions icon.png
Issue date:	08/10/1989
From:	Hunsader S COMMONWEALTH EDISON CO.
To:	Murley T Office of Nuclear Reactor Regulation
References
NUDOCS 8908170611
Download: ML20245J260 (3)

Text

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x Commonwealth Edison

,' 7 72 West Adams Street, Chcago, ll!.nois X3 dress Reply to: F5st DffTc6B5iiT07-

• Chcago. tilinois 00690- 0767 August 10, 1989 Dr. Thomas E. Murley Director of Nuclear Reactor Regulation US Nuclear Regulatory Commission Washington, DC 20555 Attn: Document Control Desk

Subject:

Zion Nuclear Power Station, Units 1 and 2 Proposed Amendment to Technical Specifications Section 3.15. " Auxiliary Electric Power System" License Nos. DPR-39 and DPR-48 BC Docket Roi.,_50-295 and 50-304

Reference:

(a) July 6, 1989 letter from G.E. Trzyna to US NRC/NRR (b) August 4, 1989 letter from G.E. Trzyna to US NRC/NRR 3

Dear Dr. Murley:

Reference (a) provided data to support the proposed Technical Specification amendment which would allow a 45 day outage of the "0" Diesel Generator (DG) during the forthcoming Unit 1 Refueling outage. Subsequent to your review of that submittal, several telephone conference calls between CECO /NRR personnel indicated the need for clarification to some items.

Reference (b) provided this clarification. On August 9, 1989, an additional conference call was held with NRR personnel.

The purpose of this letter is to provide the additional information requested.

With respect to reference (b), the following items listed in the document are being revised or added under Category 1 to ensure that plant operations will be conducted in a safe and prudent manner during Unit I refueling outage.

a. The following item of Category 1 is being revised:

Item 6. Change from "No mid-loop operations are planned for this outage while fuel is in the vessel" to "No mid loop or reduced RCS inventory operations, as defined in Generic Letter 88-17, will be performed during this outage period while fuel is in the vessel.

b. The following items are being added to Category 1:

Item 8. During the cooldown period on Unit 1, both high pressure safety injection systems will be available for  ;

operation. l 8908170611 890810 PDR f1 DOCK 0500029b P PDC I g .

- Lbr.T.E.Hurley - 2 - August 10,'1989

, Item 9. Maintenance will be performed on the.1A Centrifugal

, Charging pump during the' outage period. Though, it is powered by the "0" Diesel Generator, it will have no effect on plant operations during the'"0" Diesel Generator.out-of-service period.

+

Item 10. The IB Centrifugal Charging pump, which is powered from Bus 149, will be available~for operation during the outage period whenever-fuel.is in the vessel. However, maintenance will be performed on the pump during the

. period when fuel is not in'the vessel.

Item 11 Intermediate head safety injection 1A and IB will be available for operation.untillthe reactor vessel head is-removed. However, maintenance will be performed on the pumps during the period when. fuel is not in the vessel.

Item 12. General maintenance on ESF buses 148 and 149 will not be performed during the Unit-1 refueling outage period until after "0". Diesel Generator has been returned to l an OPERAPLE status. However, maintenance will be performed on 3F busses 147 and 137 during the "0" Diesel Generator out-of-service period.

Item 13. 1B and IC Service Water pumps will be available for operation during the "0" Diesel Generator out-of-service period.

Item 14. Unit 1 and 2 Component Cooling Hater System pumps and heat exchangers will be operated in accordance with Zion Station Technical Specification Section'3.8.5. A during the unit I refueling' outage.

Item 15. Gravity flow from the RHST will always be available to the reactor while the level is.below the reactor vessel flange and fuel is in the vessel,

c. The following information is being provided for Category 2.

QUntlRO: Previous submittals have discussed core nielt frequency as a basis for judging the merits of the proposed Technical Specification change allowing a 45 day outage on the "0" diesel generator. Does this basis change, when one considers frequency of serious release (as'an induce to public l risk) instead?

Antw_er: The Zion Probabilistic Safety Study (lPSS) indicates that the dominant contributor (by nearly a decade) to serious release frequency.is a seismic induced loss of all AC power.

Further, the two major. vehicles for that event are a failure of the service water system due to crib house failure and.a failure of all dieseis and related switch gear due to' auxiliary building.

structural follure. These events are insensitive to the duration of the "0" diesel generator outage ~as depicted in this submittal. Other transient induced contributors ~to frequency of serious release are low enough in relative frequency that one may readily judge that the effects of extending the "0" diesel

l. outage as requested will have a negligible impact on that frequency.

v

., 7 6, ; Dr. T.E. Murley' -

34 - August 10, 1989-It is-Edison's' understanding that this information answers and resolves the questions raised by the;NRC Staff regarding.the-Technical =

Specification Amendment request.

Please direct any questions'regarding this submittal.to.this office.

Very.' truly your s, b'I == =&

S.C. Hunsader Nuclear. Licensing Administrator scl/0242T:1-3 cc: Chandu Patel-NRR Resident Inspector-Zion J.. Hinds-RIII l