ML20031C216

Safety Review Approving Proposed Tech Spec Change 92, Allowing Replacement of Reactor Vessel Closure Studs

ML20031C216
Person / Time
Site:	Yankee Rowe
Issue date:	10/02/1970
From:	Burger A US ATOMIC ENERGY COMMISSION (AEC)
To:
References
NUDOCS 8110060642
Download: ML20031C216 (4)

Text

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...Q,.A UNITED STATIS gl ATOMIC ENERGY COMMISSION ( 'i

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WASHINGTON.- D.C. 20545

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Fila (Occhet No.f50-29) g TERU:

R. d' Shhe=hl,,.. Chief, 023 #1,'DRL

.. 'p,}, geb -A SAFETY REVIEW OF PROPOSED CHANCE No. 92 - YANKEE ATOMIC ELECTRIC COMPANY -

YANKEE ATOMIC POWER STATION

, Py' letters dated August 31, and Septe=ber 15, 1970,. Yankee Ato ic Electric

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Company requested cu:hori::ation of 2roposed Change No. 92 to 'the Technical Specifications of Facility License No. DPR-3 for the Yankee _ Kuclear Power S:ation.

'he proposed change would allou. replace =ent of'the.5-1/4 inch

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dic=eter reactor vessel closure studs with 4-3/4 inch dia=eter studs.

Threaded sleeves will be inserted in the reactor vessel flange which will; receive the replacement studs.

'"hread damage -- sny vessel closure stud hole or stud would be repaired by installation or a threaded bushing into the vessel flange and a replace-'

= ant stud of reduced dia eter.

The =ethod of ins:cIlation and the higher strength =aterial of the s= aller dicater stud would be the sc=e as those used for the si=ilar replace =ent stud No. 36, which hcs previously been evaluated and found acceptable in Change No. 84.

Eased on our calculations, we had determined that the pro-posed 4-3/4 ine't dic=eter stud was equal to the e::1 sting 5-1/4 inch dia=eter -

stud in design and effectiveness. We have now deter =ined th:t our previous conclusions till hold even if all existing 5-1/4 inch diameter studs were replaced in the =anner proposed.

In this deter =ination, we hcVe considered the vessel =anufacturer's cnalysis which shows that the reduction in the ligc=ent between stud holes by insertion of two adjacent threaded seves vill have no insignificant effect on the liga =ent strength; also, that the tailable fatigue life of each replace =ent stud (allowable 300 cycles of hectup and cooldown) will exceed the lifetime of the reactor vessel.

The licensee proposes a vole =etric examination of cll replacement reactor vessel studs to be performed during every refueling outage. We find that the proposed surveillance require =ent is acceptable.

In view of the foregoing, ve have concluded that the proposed chcnge does not involve significant hazcrds considerations and there is reasonable cssurance thc: the hecith and scfety of the public will not be endangered by operc ion in the =cnner proposed.

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p.. /Qw A. Burger.

Operc ing Reactor Branch #1 Division of Reactor Licensing 8110060642 701002~

PDR ADOCK 05000029.

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