ML20210D663

Forwards Results of Investigation of Allegation 147 Re Different Electrical Vitalities W/Common Support.Nrr Requested to Assume Lead for Evaluation & Closeout

ML20210D663
Person / Time
Site:	Diablo Canyon
Issue date:	03/12/1984
From:	Bishop T NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
To:	Eisenhut D Office of Nuclear Reactor Regulation
Shared Package
ML20210D653	List: ML20210D649 ML20210D658 ML20210D663 ML20210D675 ML20210D700 ML20210D709 ML20210D716 ML20210D726 ML20210D749
References
FOIA-86-197 NUDOCS 8609190295
Download: ML20210D663 (5)

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'g h 'f.[g[5 1450 MAHIA LAf4E SUITE 710 WA L NUr CRE E K. C,11.t FOR *Jt A 94596 If,AR 12 584 MEMORANDUM FOR: D. G. Eisenhut, Director Division of Licensing, NRR FROM: T. W. 31s'ncp. Director Division of Reactor Safety and Projects, Region V

SUBJECT:

ALLEGATIONS REGARDING THE SUPPORTING OF DIFFERENT ELECTRICAL VITALITIES PROM A COMMON SUPPORT; ALLEGATION NO. 147, ATS No. RV *4-A-0015 Region V has recently examined the subject concern. The results of our investigation are attached. As noted under " Action Required," we indicated that this matter vauld be referred to NRR for use in your evaluation of acceptability of at FSAR amendment request, to be submitted. by the licensee.

Accordingly, Regian V requests that NRR assume lead responsibility for the evaluation and cicsaout of this issue. If you have any questions regarding this matter, please contact D. F. Kirse$ of Region V.

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T. W. Bishop, Director Division of Reactor Safety and Projects Enclosure cc: G. Knighton, LH3, NRR H. Schierling. LB3, liRR Allegation File No. 147 gg7 PDH

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Allegation er Concern Number: 147 h

i ATS No. RV 84 A 0015

, Characterization Cable tray and coaduits of independent and redun. dant trains were installed on ccamon raceway supports. (No specific examples were given by the allegers).

Implied Significance to Plant Design, Construction, or Operation i The required independence of circuits that are essential to emergency reactor shutdown, containment and reactor heat removal, or otherwise essential in i

preventing significant release of radioactive materials to the env.ironment is i

compromised by the possibility of conaon failure through the coneon suppsrt.

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- t Assessment of Safety Significance This issue was reviewed by; (1) by review of NRC regulatory requirements and industry standards within the topic area, (2) examination of approved licensee commitments as stated in the FSAR, and (3) extensive field inspections of 1

Class I raceway supports to determine if common supports had in fact been I

utilized. .

There is no generic requirement by the KRC to install redundant circuits cn ,

t separate supports. Indeed, most facilitlen, even those mast recently ,

licensed, such a,s Washington Nu'elear Project Number 2 (GNP 2), feature common i

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supports of redundant safety related electrical divisions, The requirements are that the redundant safety related e.lectrical circuits asust be (1) electric 311y independent of each other and (2) physically separated frca each other in order to preclude in the .first. case comon elect rical f ailure: that wcuid rend:tr both circuits incperablat or it. the second case that conmon harms

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h such as fire or missile hazards would affect both circutts. With respect to sopports, if the support is seis'nically designed to vithstand the daci n 3basic earthquake with its total load imposed, it ir, acceptable.

The adequacy of tha tray cupporting system is revie'wed with respect to the i

1 ability to perform the intended safe.ty function m6er the postulated f.eismic event. This review of safety related receway supporticg systens does noti require inclusion of the independence criteria. The ERC plsition is expressed in PEGULATORY GUIDC 1.29 which requires that ss,fety related electrscal cystema t

have supports that are designcd to withstand F.he efit'ects of tLe safe shutdown cartbquake and remain functional. There is ' no racnt. ion in this P,ECUIATORY GUIDI of any re4airemeat t.o provide independent cupports.

Tha adequacy of safety related electrical systems with rcspect te electrical independence and pbysical separation is defined in .1EEE 30ft and IEEE 384 (EMLATORY GUIDE 1.75). These standards stt';e tne requirunents for physical separat. ion of redundant circaits in terms of siistance or berriers bat remain i

silent ec to any requirements of the raceway supporting system.

The speMiic separations of IEEE 384 (REGULAT0hY GUIDE 1.75) were e,ot imposed upon the licecsee beccuse the license:'s proposed wethods as stated in the l'SAR Amend:1ent 24 wcre fouc& aedept.able by the NRC Staff. (See Suppletent No.

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1 to the Safety F.yaluktion of the Diablo Canyon Nuclear Power Station Units 1 and 2) dated 31 January, 1975.

i The specific requireeents are stated in FSAR Secti<n 8.3 3 " Analysis of A-C Power Systems", Separation Criteria for Class I Systems" on page 8.3-19.

On page 8.3a28 of the ESAR under the title " Supports" is a reference to l

reccion 3 10 for the seismic design and a statement that " Class I supports are oot shared by mutually redund,1nc Class I circuits".

T'aerefore, the inspector concludes that althcugh there is no fire regulatory requirement to support differen.t divisions on separate support systems, the

. licensee added this commitment to the FSAR to provide additional conservatism.

. t An hKC inspector conducted extensive examinationg of Unit I areas containing large contentraticas of cafety related electrical cable raceway to determine s

whether the elleged condition existeC. The inspector observed that aeveral raceway supports in the esble spreading room supported ccaduit of redundant 1

} Class I divisions.

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1 At the inspector's request the licensee evaluated this situation. The licensee stated by letter (DCL-84-064) dated Fettuary 17, 1934, that " supports in the cable spreading ruon under the ccattol room and the K area, elevatica 100'" sere exceptions to the design approach of assuring that mutually redundant Class I conduits and trays were not supported by shared s6pport systems. This response from the licensee gino stated that Section 8.3.1 of the FSAR was in process of 'being updated to reflect this plant condition. JThe licensee's re ponse.hewever d,1,d not address the degree of compliance Vith the ,

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FSAR commitment and the engineering justifictaion for failure to implement the i

FSAR Commitment. The licensee supplied additional infonmation related to this issue by Letter No. DCl-84-092, dated March 7. 1984. The enclosure to this

, Letter states that "The FSAR statement that Class I supports are not shared by -

hutually redundant circuits was a design conservatise established by PG&E;

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l however, deviation from this design standard was found to be required to show

! seismic quali.fication of raceways to the revised seismic spectra generated during the Diablo Canyou Phase 1 Verification Program. Prior to acceptance of this design standard change, reviews were performed which showed that no f regulatory requirements, including those st.ated earlier, were impacted. The 1

4 design of supports has sufficient margin to assure that loss of a single ,

I support will not cause 'los s of safety functien. As stated in the previous submittal on this issue, an FSAR change will be submitted to clarify Page 8.3-28." Thus, it appears that the licensee had evaluated this change in

design criteria, for compliance with regulatory requirements, with the result j that the deviation from the additional conservatism, previously committed to J

in the FSAR, was justified based on analysis of regulatory requirements and i

j industry standards. Furthermore, the licensee's engineering had brought ttis l issue to the attentica of the organization responsible for submitting requests I

for amendment of the FSAR. Although an amendment request had not yet been i

i submitted this item was scheduled for inclusion in an amendment request.

Therefore, the staff feels that the licensee acted in responsible manner as

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regards this situation; however, a more timely action to resolve the FSAR discrepancy would have been desirable. The staff feels tha't this situation l

does not represent a breakdown in the design process.

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The failure to comply with the above referenced FSAR commitment is considered to be a Deviation.

Staff Position Inspection of Unit I cable spreading room area indicated that the licensee did not comply with the provisions of the FSAR with respect to independence of supports for redundant safety related circuits. This represents a Deviation from in ESAR commitment.

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. Action Required The matter of acceptability of the installed supports will be referred to the Office of Nuclear Reactor Regulation for use in their evaluation of the FSAR change, which PG&E will submit. No further regional action is anticipated.

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