ML19323G566

Forwards Comments on Draft Rept Re Probabilistic Safety Analysis for Dc Power Supply Requirements at Nuclear Power Plants.No Major Problems Exist W/Content of Draft Rept

ML19323G566
Person / Time
Issue date:	04/04/1980
From:	Novak T Office of Nuclear Reactor Regulation
To:	Baranosky P NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES)
References
NUDOCS 8006040448
Download: ML19323G566 (2)

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MEMORANDUM FOR:

P. Baranowsky. Task Leader, PAS M.',. S. B i?!f d

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CGNENTS ON DRAFT REPORT Olt PROBABILISTIC SAFETY..S s W;w S.

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-.Vq ANALYSIS FOR DC POWER SUPPLY REQUIREMENTS.AT NUCLEAR y %,.

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a Enclosure COMMENTS ON DRAFT DC POWER SUPPLY REQUIREMENTS l

1.

Pg. 8:

Major assumption number 2 on page 8 states that "only relatively high probability initiating events and DC power system failures which require initiation of shutdown cooling were analyzed in this study." The way the assumption is written may lead a reader to believe only high probability DC power system failures are considered, not all DC power system failures.

The phrase "relatively high probability" needs to be expanded upon so that a reader can understand which events are included or excluded.

2.

Pg. 18:

The AFWS design assumed in the analysis is a 3-train system, but many operating plants have only 2-train systems.

Discuss the probabilistic ti impact of 2 trains.

3.

Pg. 20: The discussion of the HPI system implies that after receiving a safety injection signal, all three charging pumps are operating. At many nuclear units two charging pumps start on an SIS and the pump normally operating shuts off.

Discuss the impact of two rather than three operating pumps.

4.

Pg. 41:

The analysis assumes that the HPI pumps cannot reach a discharge head equal to safety valve pressure setpoint, but all B&W plants and about half of the W plants have high head centrifugal pumps capable of lifting the safety valves.

Discuss the impact of these high pressure pumps and 'N fact that " feed and bleed" is not considered.

" Feed and bleed" would have an impact on paths 4, 8,15,18, 22, 29, 32, and 36 in Figure 11.

5.

Pg. 1 :

Your summary implies that the major goal of the report is.to demonstrate (pro or con) that the failure of the DC power supply system represents a small contribution to the probability of a core melt accident.

The summary should note that your analysis process precludes discovering rare events which may cause core melt but rather concentrates on the more probable concerns which may lead to serious core damage.

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e APR 4 1980 NQA Main Committee Letter Ballot #29 on Proposed IEEE Standard 467-1979, Quality Assurance Program Requirements for the Design and Manufacture of Class 1E

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Instrumentation and Electric Equipment for Nuclear Power Generating Stations" (Draft 6, December 1979).

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Disapproved i

Crisinal Signed by I

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l W. M. Morrison, Member NQA

Enclosure:

Comments I

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R. B. Minogue R. G. Smith G. A. Arlotto i

W. M. Morrison i

E. C. Wenzinger D. F. Sullivan T. G. Scarbrough 1

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W. M. Morrison's Coments on Proposed IEEE Standard 467-1979, Ouality Assurance Program Requirements for the Design and Manufacture of Class 1E Instrumentation and Electric Equipment for Nuclear Power Generating. Stations (Draft 6, December 1979)

Comments on Draft 5, Rev. 4 of the proposed standard that were enclosed with my

" Disapproved" ballot dated July 15, 1979 have not been resolved to my satisfaction and, thus, are applicable to Draft 6.

As previously stated, the proposed standard contains only general requirements and does not provide details o~n the implemen-tation of these requirements by manufacturers of Class IE instrumentation and electric equipment.

For example, only nine of the eighteen sections of the proposed standard describe additional controls beyond ANSI N45.2-1977 or the N45.2 daughter standards.

Supplement 1, " Supplementary Requirements for Class 1E Standard Catalog Items," does provide useful controls in this area.

However, this supplement and the nine sections mentioned above do not constitute sufficient material to warrant publication of a separate IEEE standard.

Some of the changes that have been made to the latest draft provide improved gui-dance, while others are basically editorial.

The minimal improvement in guidance as a result of these changes is not sufficient to justify my support.

In regard to Section 18.0, Audits, the proposed standard significantly weakens the requirements of ANSI N45.2.

Specifically, an evaluation which determines the need for an audit is stated as acceptable in the proposed standard for meeting internal audit requirements.

The basis for audit requirements is to provide a means to verify the compliance of an organization with all aspects of its Quality Assurance Program.

Clearly, an evaluation to determine the need for an audit does not ade-quately ensure this compliance.

Therefore, the guidance provided in the proposed standard that allows an " evaluation to determine the need for an audit" to meet the requirements for internal audits should be deleted.

Similarly, the proposed standard allows the use of periodic evaluations to satisfy external audit requirements.

The required frequency of external audits may be j

reduced through the use of periodic evaluations; however, the use of these evaluations to eliminate the requirements for external audits is unacceptable. The proposed standard should be revised to state that external audits are required.

Also, the interval between these audits may be determined by the use of periodic evaluations but the maximum allowed interval between audits shall be three years.

The proposed standard should be revised to reference the NQA-1 document to further the ongoing effort to provide consistent QA guidance throughout the industry.

Since the proposed standard currently references ANSI N45.2 and its daughter standards, additional guidance should be provided by referencing all applicable daughter standards.

In particular, Sections 2.0, Quality Assurance Programs, 4.0, Procure-ment Document Control, and 18.0, Audits, should reference ANSI N45.2.6-1978, j

ANSI N45.2.13-1976 and ANSI N45.2.12-1977, respectively.

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