DCL-92-157, Comment on Proposed Rule 10CFR50 Re Loss of All Alternating Current Power & Draft Reg Guide 1.9,task DG-1021.Endorses Comments Submitted by NUMARC

Comment on Proposed Rule 10CFR50 Re Loss of All Alternating Current Power & Draft Reg Guide 1.9,task DG-1021.Endorses Comments Submitted by NUMARC

ML20102A517
Person / Time
Site:	Diablo Canyon
Issue date:	07/09/1992
From:	Rueger G PACIFIC GAS & ELECTRIC CO.
To:	Chilk S NRC OFFICE OF THE SECRETARY (SECY)
References
FRN-57FR14514, RTR-REGGD-01.009, RTR-REGGD-1.009, RULE-PR-50, TASK-DG-1021, TASK-RE 57FR14514-00024, 57FR14514-24, DCL-92-157, NUDOCS 9207270093
Download: ML20102A517 (4)

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s /s Re: Docket No. 50-275, OL-DPR-80 Docket No. 50-323, OL-DPR-82

\ V Diablo Canyon Units 1 and 2 Comments on the Proposed Amendment to 10 CFR 50.63, " Loss of All Alternating CLrrent Power"

Dear Mr. Chilk:

In response to your request for coments on a proposed amendment to 10 CFR 50.63, " Loss of All Alternating Current Power," noticed in the Federal Register on April 21, 1992 (57 FR 14514), Pacific Gas and Electric Company provides the enclosed coments.

PG&E endorses the cements submitted by the Naclear Managemer.t and Re::::rces Council (NUMARC) to the NRC on Jaly 2,1992, on the proposed amendmect to 10 CFR 50.63 and dran Regulatory Guide DG-1021, as they apply gentrically to the nuclear industry. En losed are additional commenps hat are more site-specific to the Diablo Canyon Power Plant.

Diablo C!nyon's lechnical Specifications currently contain a requirement to maintain erirgency diesel generator (EDG) reliability goals and reporting requirements for not satisfying the requirement. Also, PG&E has reiterated the comitment to maintain the required EDG reliability requirements in a recent submittal to the NRC on the Station Blackout rule. Therefore, we, like NUMARC, see no need or basis for this proposed regulation.

Alternatively, we recomend the regulation be revised to include the equivalent results-oriented approach of the Maintenance Rule (10 CFR 50.65). Applying this approach would allow decreased frequency of load testing, when so justified by exceeding reliability goals, thereby increasing the overall availability of the EDGs.

Sincerely, 1

GrebryM.Rueger 58095/85K 9207270093 92o7o9 PDR PR

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50 57FR14514 PDR

PG&E Letter No. OCL-92-157 July 9, 1992 cc: -Ann P. Hodgdon John B. Martin Philip J. Morrill Harry Rood CPUC Diablo Distribution Enclosure 5809S/85K/ALN/1572 O

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PG&E Letter No. DCL-92-157 ENCLOSURE COMMENTS ON THE PROPOSED AMENDMENT T0 10 CFR 50.63 LOSS OF ALL ALTERNATING CURRENT POWER The following comments are provided cn the proposed amendment to 10 CFR 50.63 imposing new requirements related to emergency diesel generator testing and monitoring against performance-based criteria.

NRC Statement "The proposed amendments would require licensees to test and monitor emergency diesel generators (EDG) accinst criteria that indicate possible degradation from the EDG target levals selected for determining the specified station blackout duration." (57 FR 14514, Summary)

PG&E Comment Since the COPING period determined by 10 CFR 50.63 was predicated upon the selection / commitment to an EDG reliability (0.950 at Diablo Canyon), it is our understanding that the requirement to test and monitor the EDG to said reliability was already requireu within 10 CFR 50.63.

Also, the Diablo Canyon Technical Specifications require testing and monitoring the EDGs against such criteria.

NRC Statement "However, the SB0 rule did not require licensees to monitor and maintain these reliability values." (57 FR 14514, Need for Amendnient)

PG1E Comment We disagree that the Station Blackout (SB0) Rule did not invoke the requirement for monitoring and maintaining the reliability value determined within the SB0 Rule. Furthermore, in PG&E Letter DCL-92-084 (Revised Response to Station Blackout), dated April 13, 1992, to the NRC, PG&E has clearly committed to monitoring and maintaining the EDGs to the reliability value of 0.950. The NRC subsequently approved our April 13 submittal on May 29, 1992.

PG1E Comment on Monitoring of EDG Performance Fur plants such as Diablo Canyon where there ara more than two EDGs within a unit, the extension of the three failures to "all EDGs assigned to a nuclear unit" is unjustified and too restrictive.

In a unit with two ED3s, three failures in the last 20 demands of either EDG is justified, in that one EDG has had at least 2 failures in 20 demands.

58095/85K Therefore, this failure rate would be in violation of a reliability of 0.950 (i.e., equ-' tc i failure in 20 demands). However, at Diablo Canyon whera functiona! ( there are three EDGs for each unit, three failures occurring, one by each Ead, is 1 failure in 20 demands on each EDG; thereby, the reliability requirement of 0.950 fcr station blackeut would still be maintained.

It is recomended that the statement "for all EDGs assigned to a nuclear unit" be deleted from this regulation. Specifically, the following should be deleted from the propated change to 6 50.63(a)(3)(i): " ... or at any nuclear unit (i.e. combining the performance data for all emergency diesel genera + ors assigned to a given nuclear unit rather than based on each individuti emergency diesel generttor)."

PG1E Coment on Frequency of Testing It is noted that the pending Maintenance Rule focuses on performance-based regulation (PBR). One concept of PBR is that of potentially reducing maintenance, if the reliability goals are being met to increase the overall availability of equipment.

In applying such a concept here, it would be appropriate to decrease the frequency of EDG testing if the reliability goals are being exceeded. For example: with I or less failures in 40 tests, the frequency of testing should be decreased from monthly to quarterly.

In so doing, the PBR concept of reducing maintenance when reliatility goals are met to increase overall availability of the component would oe carried over to EDG testing. Note that one of the most significant chailenges to potentially damaging an EDG is a loss-of-offsite-power event when an EDG is operatino in parallel with the grid during mcnthly load testing. Recognizing that the ultimate goal of reliability is availability, by reducing the frequency of load testing the overall availability of the EDG can thereby be increased.

PC&E Com.ent on Implementation Diablo Canyon Technical Specifications require that PG&E maintain the EDGs at 0.950 or greater reliability. If this reliability goes below 0.950, the frequency of testing must increase. In addition to writing a Special Report for any EDG failure, we must also expand this report if the number of failures exceeds 7 in the last 100. Considering these Technical Specifications, it further justifies that there is no real basis for the proposed regulation.

.The proposed regulation invokes so-called TARGET reliability points. However, we already Fave such points clearly defined in our Technical Specifications.

Although the proposed regulation TARGET points are less severe than those in the Technical Specifications, the proposed new requirements still have the appearance of unnecessary regulation. It is also unclear if these TARGET points are to be invoked within the Technical Specifications.

58095/85K ,