ML20198R740

Clarifies Initial 831105 Response to Generic Ltr 83-28,Item 3.2.3 Re Diesel Generator Fast Starts,Per Conversations W/ Ja Norris.Tech Spec Change Submitted Requesting Per Engine Application of Failure Criteria

ML20198R740
Person / Time
Site:	Zion  File:ZionSolutions icon.png
Issue date:	06/03/1986
From:	Leblond P COMMONWEALTH EDISON CO.
To:	Harold Denton Office of Nuclear Reactor Regulation
References
1729K, GL-83-28, NUDOCS 8606100192
Download: ML20198R740 (4)

Text

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j C8 7%-Commonwrith Edison l G ') One Fast Nabonal Address Plaza.

Reply to. Post OfficeChicago.

Box 767 Ilknots Chicago. Illinois 60690 June 3, 1986 Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, DC 20555

Subject:

Zion Nuclear Power Station Units 1 and 2 Generic Letter 83-28, Item 3.2.3 NRC Docket Nos. 50-295 and 50-304 References (a): November 5, 1983 letter from P. L. Barnes to H. R. Denton.

(b): February 29, 1980 letter from H. R. Denton to D. L. peoples.

(c): November 18, 1985 letter from cordell Reed to H. R. Denton.

Dear Mr. Denton.

Reference (a) provided Commonwealth Edison Company's initial response to Generic Letter No. 83-28. Subsequent conversations with J. A.

Norris of your staff have resulted in the need to clarify Commonwealth Edison Company's response to Item 3.2.3 for Zion Station.

Item 3.2.3 of Generic Letter 83-28 stated;

3. Licensees and applicants shall identify, if applicable, any post-maintenance test requirements in existing Technical Specifications which are perceived to degrade rather than enhance safety.

Appropriate changes to these test requirements, with supporting justification, shall be submitted for staff approval.

Zion Station's response to this item was contained in reference (a) and stated;

3. Our present Technical Specifications coupled with the Zion l Confirmatory Order of 2/29/80 have an adverse effect on diesel generator reliability due to less and less time allowed to perform maintenance on individual engines, because of the "per unit" application of the failure related requirements. When an individual engine is a " bad actor" all engines on that unit suffer increased testing and reduced maintenance time. In the case of "0" diesel, both units suffer. A Technical Specification change has j been submitted requesting a "per engine" application of failure l criteria. ,

0 8606100192 860603 PDR ADOCK 05000295 i P PDR l

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i EMr. H. R. Denton June 3, 1986 The Zion Confirmatory Order was transmitted with reference (b).

Item B.6 of this order stated;

6. The licensee shall perform diesel generator testing in accordance with Regulatory Guide 1.108 with a corresponding change in the allowable outage time stipulated in the Limiting Condition of Operation as follows:

Numbers of DG Failures Test Interval (Days Allowable In Prior 100 Tests (R.G. 1.108) Outage Time 0 or 1 30 As is

. 2 14 As is 3 7 As is 4 3 32 hr.

5 3 8 hr.

6 or more 3 None*

• Plant must achieve hot shutdown within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and in cold 1

shutdown within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.

This requirement holds the potential for increasing the required test frequency for all of a unit's diesel generators to once every 3 days.

In addition, the allowable outage time is reduced, thus minimizing the opportunity for maintenance and maximizing the potential for a forced unit shutdown.

Zion has two dedicated diesel generators (D/G) per unit and one D/G that swings between the two units. This situation can easily produce a condition where each D/G is at least 98% reliable, but there are four failures on a given unit in the last 100 starts. This condition is illustrated in the Attachment.

The forced reduction in allowable outage time, the increased test frequencies, and the higher potential for a forced unit shutdown are all considered to degrade plant safety. This was the intent of Zion's response to Item 3.2.3.

Commonwealth Edison Company has submitted numerous requests to amend or delete the Confirmatory Order. The most recent request was contained in reference (c) which proposes that the entire confirmatory order be deleted. This request supercedes the Technical Specification change referred to in reference (a). However, the deletion of the order would also include the removal of Item B.6. This action would rescind the detrimental requirements described above and in the Attachment.

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Mr. H. R. Denton June 3, 1986 If any further questions arise concerning this matter, please direct them to this office.

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i Very truly yours,  ;

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P. C. LeBlond Nuclear Licensing Administrator I la l Attachment I

cc: Region III Inspector - Zion J. A. Norris - NRR I

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ATTACHMENT EXAMPLE OF THE APPLICATION OF ITEM B.6 Unit 1 D/G 1A D/G 1B D/G 0 Total Starts Starts

• Starts Starts 1 1 - failure 1 - success 1 - success

, . 5 - failure 20 - failure 30 - failure 40 - failure 10 0 - - - - ------- - - - - - - - - - - - -- --

100 - success j 100 - success 85 - failure 1

100 - success D/G 0 reliability = 98%

D/G 1A reliability = 98%

D/G IB reliability = 98%

Number of Unit 1 failures in last 100 starts = (lA D/G failures) + (IB D/G failures) + (O D/G failures)-b 2 = 2 + 1 + 1 = 4 I Note; an 0 D/G failure is counted as 1/2 per unit.

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Four failures requires a test frequency for each of the three D/G of once per three days and a maximum allowable outage time of 32 hours3.703704e-4 days <br />0.00889 hours <br />5.291005e-5 weeks <br />1.2176e-5 months <br />. However, the D/G'reliabilities are 98%. These additional restrictions are unnecessary and detrimental, especially for D/Gs of 98% reliability.

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