ML19323H836

Part 21 Rept Re Defective Emergency Diesel Generator Exhaust Silencer Support Sys.Seismic Design Calculated W/Base Support Plate.Drawings Did Not Indicate Base Plate.Util Informed NRC of Defect on 790302.Problem Corrected

ML19323H836
Person / Time
Site:	North Anna
Issue date:	05/29/1980
From:	Wild P STONE & WEBSTER, INC.
To:
References
REF-PT21-80-224-001 NUDOCS 8006160261
Download: ML19323H836 (5)

Text

,

s .

STONE 6 WEBSTER ENGINEERING CORPORATION 245 SUMMER STREET. BOSTON. M ASSACHUSETTS A ADDRESS ALL CORRESPONDENCE TO P.O. BOX 2323. SOSTON. M ASE 02107 W.U. TELEX:S40001 oma h NsfeuCTion o e ations

• • '*'*A u.,

• • "'On".*.

i"2'",*;

WABMINGToN*". "O.C.

SC-2AV-ooj Mr. Victor Stello, Director May 29, 1980 Office of Inspection and Enforcement U.S. Nucleae Regulatory Commission Washington, DC 20555

Dear Sir:

NOTIFICATION OF DEFECT, 10CFR21 NORTH ANNA UNIT 2 VIRGINIA ELECTRIC AND POWER COMPANY Stone & Webster Engineering Corporation (S&W), pursuant to the provisions of 10CFR21, hereby provides notification of a " defect" concerning the North Anna Nuclear Power Station, Unit 2, owned by Virginia Electric and Power Company and for which S&W provided both engineering and construc-tion services.

In accordance with the reporting requirements of Section 21.21(b)(3),

the following information is submitted:

(i) Name and address of the individual informing the Commission:

Mr. P. A. Wild, Director of Engineering Stone & Webster Engineering Corporation Post Office Box 2325 Boston, MA 02107 (ii) Identification of the facility, or the basic component supplied for such facility, which contains a defect:

North Anna Nuclear Power Station, Unit 2 Emergency Diesel Generator Exhaust Silencer Support System - Seismic Protection (iii) Identification of firm constructing facility or supplying basic component which contains a defect:

Basic component supplied by Colt Industries, Fairbanks-Morse Engine Division.

• ooeieo 237

.VS 2 May 29, 1980 (iv) Nature of the defect and the safety hazard which could be created by such defect:

The diesel generator exhaust silencer support system contained a departure from the technical requirements specified in the procurement document. The specification for the diesel generator contains the following provision:

The-diesel generators must withstand the Design Basis Earthquake (D3E). The DBE acceleration values are specified.

Review of the diesel generator manufacturer's seismic calculations revealed that the calculations were based on a design which utilized a plate under the exhaust silencer support system. However, the plate was not indicated on the manufacturer's installation drawings and was not installed. Analysis indicated that the support system, as installed, could not withstand the forces imposed by the DBE.

Under the adverse conditions of a seismic event, the exhaust silencer could collapse and become blocked, thereby degrading the performance of the diesel generator.

The diesel generators are necessary, under design basis events, to assure the capability to shut down the reactor and maintain it in a safe shutdown condition. Since power to safety-related components is supplied by the diesel generators, degradation of their performance represents a major reduction in the degree of protection provided to the public health and safety and represents a substantial safety hazard.

(v) Date on which information of such defect was obtained:

May 29, 1980 (vi) In the case of a basic component which contains a defect, the number and location of all such components in use at, supplied for, or being supplied for facilities subject to the regulations:

North Anna Unit 2 - two systems North Anna Unit 1 - two systems

-(vii) Corrective action which has been taken; name of individual or organization responsible; and length of time taken to complete the action:

Corrective action was taken by Virginia Electric and Power Company and S&W and completed on 2/4/79 (Unit 1) and 5/17/79 (Unit 2).

~ l

.f L

VS 3 May 29, 1980 Each exhaust line was modified to provide a parallel exhaust path originating within the service building structure. Each diesel generator's exhaust can be aligned to discharge from a seismically supported unmuffled exhaust line in addition to the existing muffled exhaust arrangement. A flexible self-detaching fabric connector

- has been incorporated in the exposed portion of each muffled exhaust line downstream from each exhaust line service building penetration. The flexible connectors will prevent poteerially damaging muffled exhaust line movemencs, introduced from external sources, from being transmitted back to the associated unmuffled exhaust line within the building structure. Operating the diesels in this vendor-approved manner presents no operational reliability problems.

In order to reduce the low pitch operating drone of diesels during periodic operations,.the unmuifled exhaust lines are secured by manually operated high temperature i valves.

t (viii) Advice related to the defect that has been given to purchasers or licensees:

No other actions, apart from the specified modifications,

.were necessary to bring the systems into compliance with the specification.

) I'dentification of this defect and the filing of this report are results of a review of 10CFR50.55(e) Reports and Licensee Event Reports filed by S&W clients since January 6,1978. This review, committed to in our letter to NRC of September 6,1979, resulted from the NRC special in-spection of May 1-4, 1979. NRC has been previously advised of the problem with the emergency diesel generator exhaust silence support system by the following notifications and reports made by Virginia Electric and Power Company:

1. Notification on January 31, 1979 in accordance with 10CFR50.55(e) 4 with respect to North Anna Unit 2.

2. 10CFR21 report contained in Vepco letter Serial No. 061 dated February 5, 1979, with respect to North Anna Unit 2, including a statement that similar components existed on North Anna Unit ~1.

3. . License :. cat report No. LER 79-005/0lT-0 contained in Vepco 1etter Serial No. 083, dated February 12, 1979, with respect to. North-Anna Unit 1.

f u

e .' e e

VS 4 May 29, 1980

4. Written report in accordance with 10CFR50.55(e) contained in VEPCo letter Serial No. 061A dated March 2,1979, with respect to North Anna Unit 2.

If you require any further information, please contact S. B. Jacobs at 617-973-5264.

Very truly yours, P. A. Wild Director of Engineering JBS:mra d ,

i i

. ,4 .

ATTACED IS A PART 21 REPORT FROM IE IMIL UNIT - ROOM 359E/W PART 21 IDEMIFICATION 10. 70 4 4Y-oo/ CGPANY NAFE h @

DATE OF lETER 69# o DOCET ID, to - 3 39 DATE DISTRIBtJTED 5/3slf'd ORIGINAL REFORT _ SUPPLEIMARY &

~ ~

DISTRIPETION: .. 3

_ ~, . : ~

FUEL CYCLE & SAFEGUARDS (S)

REACTOR (R)( _ _

f%TERIALS(M)

NRR/ DOR, DIRECTOR (2) AD/FFFEI- AD/SG-IE NRR/DPM DIRECTOR (2) tESS/FGE AD/ROI AD/ROI(2) REGIONS REGIONS AD/RCI IEFILES NRR/ DOR,DIPECTOR REGIONS PDR NMSS/SG SS-881 IEFILES LPDR PDR

/N CENTPAL FILES-SS-396 LPDR CENTRALFILES(CHRON) TEPA PDR GAL FILES (CHRON)

IE FILES (2)

TERA 1.PDR CENTPAL FILES 016 TEPA LOEB/FPA FT4B5715 CENTRAL FILES (CHR0tD AE0r; - fMB-762 CENTPAL FILES - SS-396 LDEB/tPN f1857k5 AEOD tiiBB-7602 L0EB/fPA FiiB 5715

. AE00 !IDJ-76C2 ACTION:

PRELIMINARY EWALATION OF THE ATTACHED REPORT INDICATES LEAD RESPONSIBILITY FOR FOLLGi-UP .AS SH0'41 BELG4:

JEO tm E EE OMC RCI SG FFFSI PEy,