ML20133N203

Submits Util Schedule for Resolution of Concerns Associated W/Use of Pipestress Code at Facility,Per 790312 Telcon

ML20133N203
Person / Time
Site:	Maine Yankee, 05000000
Issue date:	03/12/1979
From:	Nelson C Office of Nuclear Reactor Regulation
To:	Reid R Office of Nuclear Reactor Regulation
Shared Package
ML20133M133	List: IA-85-301, Forwards Draft Temporary Instruction Providing Guidance for Inspecting & Evaluating Licensee & CP Holder Responses to IE Bulletin 79-14, Seismic Analysis for As-Built.... Comments Requested by 790723.Supporting Documentation Encl ML20133M130 ML20133M162 ML20133M174 ML20133M190 ML20133M211 ML20133M223 ML20133M232 ML20133M247 ML20133M261 ML20133M293 ML20133M428 ML20133M451 ML20133M483 ML20133M505 ML20133M523 ML20133M555 ML20133M575 ML20133M607 ML20133M621 ML20133M635 ML20133M646 ML20133M662 ML20133M685 ML20133M699 ML20133M722 ML20133M737 ML20133M757 ML20133M771 ML20133M786 ML20133M842 ML20133M853 ML20133M891 ML20133M908 ML20133M919 ML20133M959 ML20133M996 ML20133N121 ML20133N130 ML20133N148 ML20133N166 ML20133N203 ML20133N381 ML20133N390 ML20133N407 ML20133N418 ML20133N421 ML20133N434 ML20133N440
References
FOIA-85-301 NUDOCS 8508130407
Download: ML20133N203 (2)

Text

M UNITED 5TATES h+#  %^*t NUCLEAR REGULATORY COMMisslON

',, WASHINGTON, D. C. 20566

% j March 12,1979 Docket No. 50-309 NOTE T0: Robert W. Reid, Chief, Operating Reactors Branch #4, DOR FROM: Chris Nelson, Project Manager, Operating Reactors Branch #4, DOR

SUBJECT:

USE OF STONE & WEBSTER PIPESTRESS CODE FOR THE MAINE YANKEE FACILITY In response to my phone request of March 9,1979 Yankee Atomic Power -

Company provided, by phone on March 12, 1979 the following schedule T ZsD.

for resolution of concerns associated with the use of PIPESTRESS code is'; g .

at Maine Yankee: ;g;n;g -

1.

Systems - Systems affected have been identified - They are all those analyzed by S&W including Class I piping attached to reactor coolant piping and Class 2 ECCS piping. ,

2. Preliminary Analysis - Analyses to categorize piping stress levels as below code allowables; above allowables but below yield; or above yield will be complete by April 2,1979. S&W transfer to information to key cards will take until March 23, 1979.

3 Final Analysis - No schedule proposed for check of hanger design or final modifications.

.tu -

Chris Nelson, Pfoject Manager Operating Reactors Bianch f4 Division of Operating Reactors 8508130407 850703 FOIA PDR I HERRMAN85-301 PDR I

1

_ _ . _ _ _ _ _ __ __ - - _ . - - ~ - - - - -

March 12, 1979 DAILY HIGHLIGHT ,

QUESTIONABLE PIPE STRESS CODE USED BY STONE & WEBSTER ON FIVE PLANTS I '

In continuing its followup on an initial Licensing Event Report of l October 27, 1978 on Beaver Valley, 00R learned for the first time '

on March 8,1979 that Stone & Webster used an unconservative version .

of its PIPESTRESS code to calculate seismic stresses on safety-related-pipes and pipe supports. Algebraic sumation was used instead of the accepted techniques of summation of absolute values or taking the square .

root of the sum of the squares of the absolute values (SRSS). The code version used resulted in predicting stresses significantly lower than ,

would be predicted by currently accepted techniques. Use of a newer code, NUPIPE, considered to be acceptably conservative, yielded unacceptable stresses in two of the three pipe runs then at issue. .

~

Because of the potential generic aspects of this matter, Duquesne Light h Company and Stone & Nebster were asked to identify whether any other , n safety related piping systems could have unacceptable stresses when -

/

analyzed by NUPIPE or another code acceptable to us. Further, Stone and Webster was also asked to identify any other plants that used the

'nconservative version of PIPESTRESS to calculate stress levels in

'ety-related piping. Four other plants are involved: Fitzpatrick,

..aine Yankee, and Surry Units 1 and 2. ~ '

Efforts '<!:r: initi:ted by Stone & Webster on March 9,1979 to obtain the requested information on an expedited basis. D0R dispatched technical staff to the Stone & Webster Boston offices over the weekend, as did Duqu3sne Light Company, to monitor this effort. Also on March 9 00R called the other licensees to inform them of this potential problem and to request that they also infom the NRC of any safety systems that could be adversely affected, the extent of possible overstresses, and the schedule for forwarding this infomation. A preliminary response from all licensees has been requested by Monday, March 12.

At the present time three of the five plants are operating and two are shut down. (Surry Unit 2 is shut down for steam generator replacement. Beaver Valley shut down March 9 and Duquesne Light Company.has indicated that the plant will not be restarted without prior notification of DOR).

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