ML19290E109
| ML19290E109 | |
| Person / Time | |
|---|---|
| Site: | Yankee Rowe |
| Issue date: | 02/27/1980 |
| From: | Vandenburg D YANKEE ATOMIC ELECTRIC CO. |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| TASK-03-07.B, TASK-03-08.D, TASK-3-7.B, TASK-3-8.D, TASK-RR WYR-80-24, NUDOCS 8003040277 | |
| Download: ML19290E109 (2) | |
Text
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TwX 7tO 390-0739 YANKEE ATOMIC ELECTRIC COMPANY s.3.2.1
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February 27, 1980 United States Nuclear Regulatory Commission Washington, D.C.
205F5 Attention: Of fice of Nuclear Reactor Regulation Re fe re nce :
(a) License No. DPR-3 (Docket No. 50-29)
Subject:
Basis for Continued Operation During Evaluation of Asymmetric LOCA Loads Gentlemen:
This letter puts forth Yankee's evaluation of the basis for continued operation of the Yankee Nuclear Power Station during the period when the plant is being evaluated for the affects of LOCA loads on systems components and structures.
At the time of the licensing of Yankee Nuclear Power Station, the explicit consideration of the mechanical and structural effects of a loss of coolant accident was not a design requirement. The facility was designed and constructed to ensure that a LOCA would not occur.
Followdre are sone of the design bases and conservatisms affecting the reactor coolant pressure boundary:
1.
The plant was designed for a pressure of 2300 psia at 5500F.
It currently operates at 2000 psig nominal, affording a direct reduction in pressure stress; 2.
The pipe, fittings and welds received NDE equivalent to current day practice; 3.
Each hot leg was cold sprung to reduce operating stresses; 4.
The plar.t is base loaded, which reduces the number of fatigue cycles; 5.
The PWR primary system environment in genertl is benign, and Yankee plant history in particular is free from service induced piping failures in the primary system; 9
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s U.S. Nuclear Regulatory Commission February 27, 1980 Attention: Office of Nuclear Reactor Regulation Page 2 8
6.
In-service inspections have shown primary system welds to be f ree f rom unacceptable indications 7.
There are numerous industry studies that support the extremely low probability of large pipe breaks in systems fabricated to quality standards.
The issuance of a new design requirement does not suddenly alter the real or perceived safety of a facility unlecs there is a credible technical basis behind the requirement.
It is our technical judgement that there is no new information supporting a change to the conclusion that a LOCA is highly improbable for the Yankee Nuclear Power Station.
For this reason we believe continued operation while we evaluate the effects of a newly imposed design requirement imposes no undue risk to the health and safety of the public.
Very truly yours, YANKEE ATOMIC ELECTRIC COMPANY M."
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D. E. Vandenburgh Senior Vice president JRII/kaf