ML20094F327

Interim Deficiency Rept Re Cracked Concrete Pedestals Supporting Diesel Generator Exhaust Silencer Tank.Initially Reported on 840702.Support Sys for Exhaust Silencers & Diesel Generator Trains Redesigned

ML20094F327
Person / Time
Site:	Seabrook
Issue date:	07/30/1984
From:	Devincentis J PUBLIC SERVICE CO. OF NEW HAMPSHIRE, YANKEE ATOMIC ELECTRIC CO.
To:	Starostecki R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
References
SBN-700, NUDOCS 8408100013
Download: ML20094F327 (3)

Text

1 SEABROM STAM Engineering Omce-IPUBLIC Companyof NewSERVICE Hampsher e 1671 Worcester Road Framingham, Massachusetts 01701 (617) - 872 - 8100 July 30, 1984 SBN-700 T.F. Q2.2.2 United States Nuclear Regulatory Commission Region I 631 Park Avenue King of Prussia, PA 19406 Attention: Mr. Richard W. Starostecki, Director Division of Project and Resident Programs

References:

(a) Construction Permits CPPP.-135 and CPPR-136, Docket I Nos. 50-443 and 50-444 (b) Telecon of July 2, 1984, A. L. Legendre (YAEC) to J. Beall (NRC Region 1)

Subject:

Interin 10CFR50.55(e) Report; Diesel Generator Exhaust Silencer Pedestal Cracking

Dear Sir:

On July 2, 1984, we reported a potential 10CFR50.55(e) deficiency to Region I [ Reference (b)] regarding cracked concrete pedestals supporting the Diesel Generator Exhaust Silencer Tank.

It has been determined that this item is reportable under 10CFR50.55(e).

The following information is being filed pursuant to the interim reporting provision of 10CFR50.55(e)(3).

A. Description of Deficiency The set of concrete pedestals which support the exhaust silencer tank for Diesel Generator A, cracked during operational testing.

The cracking occurred because the pedestal base plate details did not account for the thermal expansion of the exhaust silencer's steel support saddles. The support saddles, which experience temperatures in excess of 2000F, expanded more than the anchor bolt clearances provided at the base plate. Excessive restraining forces developed in the anchor bolts and at the corners of the concrete pedestals where the anchor bolts are located.

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United Ststss'Nuclter Regulstory Ccamiesicn July 30, 1984 Attention: Mr. Richard W. Starostecki, Director . Page 2 In addition, temperatures in excess of 2000F were experienced by the' top portion of the concrete pedestal. These temperatures are greater than the maximum recommended concrete temperatures for

. sustained operation.

B. Analysis of Safety Implications If left undetected, the cracked foundation for the exhaust silencer may not be capable of supporting imposed shear loads in the event of a seismic disturbance. Should a seismic event occur of sufficient magnitude to over stress the silencer anchorage, the integrity of the silencer shell could be compromised, thus exceeding the original design criteria for the exhaust silencer. The failure of the exhaust silencer could potentially compromise the performance of the diesel generator units.

C. Corrective Action The support system for the exhaust silencers for both diesel generator trains have been redesigned. The original concrete pedestal will be replaced by a steel pedestal. The support saddles will not be insulated. The revised design also includes sufficient

^ bolt clearances to accommodate baseplate saddle temperatures up to 5000F and exial silencer expansion consistent with exhaust temperatures of 10000F. Th2 steel pedestal will enhance heat dissipation and limit concrete temperatures at the base of the steel

, pedestal to within recommended limits.

We will notify your office when the above actions are completed.

Very truly yours, YANKEE ATOMIC ELECTRIC COMPANY 1 M John DeVincentis Engineering Manager I cc: Atomic Safety and Licensing Board Service List l

Director, Office of Inspection and Enforcement US Nuclear Regulatory Commission Washington, DC 20555 l

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, William S. Jordan, III v Dfana Curran Harmon, Weiss & Jordan 20001 S Street N.W. Brentwood Board of Selectmen Suite 430 RED Dalton Road Washington, D.C. 20009 Brentwood, New Hampshire 03833 Roy P. Lessy, Jr., Esquire Office of the Executive Legal Director Edward F. Meany U.S. Nuclear Regulatory Commission Designated Representative of Washington, DC 20555 the Town of Rye 155 Washington Road Robert A. Backus, Esquire Rye, NH 03870 116 Lowell Street P.O. Box 516 -

Calvin A. Canney Mancehster, NH 03105 City Manager City Hall Philip Ahrens, Esquire 126 Daniel Street Assistant Attorney General Portsmouth, NH 03801 Department of the Attorney General Augusta, ME 04333 Dana Bisbee, Esquire Assistant Attorney General Mr. John B. Tanzer Office of the Attorney General Designated Representative of 208 State House Annex the Town of Hampton Concord, NH 03301 5 Morningside Drive Hampton, NH 03842 Anne Verge, Chairperson Board of Selectmen Roberta C. Fevear Town Hall Designated Representative of South Hampton, NH 03842 the Town of Hampton Falls Drinkwater Road Patrick J. McKeon Hampton Falls, NH 03844 Selectmen's Office 10 Central Road Mrs. Sandra Gavutis Rye, NH 03670 Designated Representative of the Town of Kensington Carole F. Kagan, Esq.

.RFD 1 Atomic Safety and Licensing Board Panel East Kingston, NH 03827 U.S. Nuclear Regulatory Commission Jo Ann Shotwell, Esquire Assistant Attorney General Mr. Angie Machiros Environmental Protection Bureau Chairman of the Board of Selectmen Department of the Attorney General Town of Newbury One Ashburton Place, 19th Floor Newbury, MA 01950 Boston, MA 02108 Town Manager's Office Senator Gordon J. Humphrey Town Hall - Friend Street U.S. Senate Amesbury, Ma. 01913 Washington, DC 20510 (Attn: Tom Burack) Senator Gordon J. Humphrey 1 Pillsbury Street Diana P. Randall Concord, NH 03301 70 Collins Street (Attn: Herb Boynton)

SEabrook, NH 03874 Richard E. Sullivan, Mayor Donald E. Chick City Hall Town Manager Newburyport, MA 01950 Town of Exeter 10 Front Street Exeter, NH 03833

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