ML19254E901
| ML19254E901 | |
| Person / Time | |
|---|---|
| Site: | Trojan File:Portland General Electric icon.png |
| Issue date: | 09/19/1979 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML19254E898 | List: |
| References | |
| TAC-07390, TAC-7390, NUDOCS 7911050036 | |
| Download: ML19254E901 (3) | |
Text
9/19/79 SAFETY EVALUATION ?.E? ORT STEAM GENE?ATOR ATER FAP.MER TROJAN NUCLEAR ?LANT DCCKET NO. 50-344 SE?TEMBER 1979
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1.0 INT:CCUCT:CN S eam generat:r water hacer has occurred in certain nuclear pcwer plar.ts as a result of the rapid c ndensati:n cf steam ir a steam genera cr feedwater line and the consequent acceleration of a slug of water hich upcn i. pact within the piping system causes undue stresses in the piping and its support system. The significance of these events varies from plant to plant.
Since a total loss of feedwater could affect the ability of the plant to cool down after a react:r shutdown, the NRC is concerned about these events occurring, even thouch an event with potentially sericus conseque :ces is unlikely to happen.
Because of the c0ntinuing occurrence of water ha.- er events, the NRC, in September 1977, informed all PWR licensees that water ha=er events due to the rapid condensation of steam in the feedwater lines of steam generators represented a safety concern and that further actions by licensees for Westinghouse and Combustion Engineering designed nuclear steam supply systems are warranted to assure that an acceptably low risk to public safety due to such events is maintained. Accorcingly, these licensees were requested to submit proposed hardware and/or proce-du*al cdifications, if any, which would be necessary to assure that the feedwater lines and feedrings remain filled with water during normal as well as transient operating conditiens. At the same time, the NRC provided eacn PWR licensee with a copy of its censultant's report, "An Evaluation of PWR Steam Generator Water Hammer", NUREG-0291.
The means employed at the Trojan Nuclear Plant to reduce the potential for steam generator water hammer include J-tubes, automatic initiation of auxiliary feedwater flew and a downward turning elbcw on each steam generator nozzle that eliminates the horizontal feedwater piping at the entrance to the steam generators.
2.0 EVALUATION Our consultant, EG&G Idaho Inc., prepared the attached evaluation of steam generator water ha=er at the Trojan Nuclear Plan as part of our technical assistance program.
(Letter from J. A.
Dearien,
EG&G, to R. E. Tiller, DCE, dated September 10, 1979.) We have rene,ed t.-is re: Ort together with the licensees submittals listed
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4.1 J. L. Williams, Portland General Electric Ccepany (PGEC), letter to W. R. Butler, NRC, Subject
" Transmittal of re;crt entitled
'Re;crt of Stea-Generat:r Feedwater F1 rer Cesign Considerations for Trojan Nuclear Plant of the PGEC'", August 6,1975.
4.2 J. L. Williams, PGEC, letter to W. R. Eutler, NRC, Subject -
" Transmittals of re;crt entitled ' Report cn Testing of Auxiliary Feedwater Addition, Fellowing J-Tube Mcd4fication to the Steam Generat:rs cf the Trojan Nuclear Plant'", October 21, 1975.
4.3 A. J. Perter, PGEC, letter to A. Schwer.cer, NRC, ~ubject -
" Transmittal cf report entitled 'Reper en Testi g of J-Tube Modification to the Stear Generators with React e Decay Heat at the Trojan Nuclear Plant'", July 12, 1976.
4.4 J. M. Conner, Dynamic Res cnse of :ne Trojan Feedwater Pice Due to Feecwater Water Hamer for PGEC, Becntel Power Corporation, August, 1975.
4.5 J. 3. Eleck, et.al, An Evaluation of PWR Steam Ger.erator Water Ha-- er, Creare, Inc. NUREG-C29i (Decen:er i976).
4.6 W. E. Bennett, Waterha rer in Steam Generator Feedwater Lines, Westinghcuse Tecnn1 cal Bulletin, NSD-TE-75-7 (June 10,1975).
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