ML19319B480
| ML19319B480 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 09/06/1977 |
| From: | Stolz J Office of Nuclear Reactor Regulation |
| To: | Roe L TOLEDO EDISON CO. |
| References | |
| NUDOCS 8001220890 | |
| Download: ML19319B480 (3) | |
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~s Distribution SEP 61977 DocketW LWR #1 NRC PDR Local PDR JStolz Decket No. 50-346 LEngle EHylton Attorney, OELD OI&E (3)
TBAbernathy Toledo Edison Coreany JRBuchanan ATTH: Mr. Lowell E. Roe ACRS (16) en 0
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Vice President, Facilities EReeves' g gv Develo ment U
Edison Plaza
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300 Edison Avenue
[ID _J, Toleco, Ohio 43552 lj g
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SUBJECT:
STEAM GEhERATOR FEECWATER FLOW IHSTABILITY (OAVIS BESSE, UNIT 1)
The EC staff continually reviews experience frc::: operating reactors tc assure that an adequate level of safety is :naintained at each individual ncclear plant and for the total population of nuclear plants. As new technical information and coerating experience becanes available, the
- RC evaluates whether such information could significantly alter the previously ceter lined levels of safety.
In this regard, we have noted Inat there have been abcut 50 reported water ha-;aer avents in lit:ht water reactnes sone of wtich resulted in structural damage to safety significant systens. Of t%se, apprcximately 20 water hamers have occurred cue to the rapid condensation of steam in feedwater lines in plants with Westinghouse and Combustion Engineering designed steain generators. Ubile for tne most part da::: age fror's these events has been liaited to picir.g supports, one event in the feedwater line of a pressurizec reater reactor did result in a significant piping failure. None of the events to date nas resulted in an adverse icpact on the health and safety of the cuolic.
It is cossible, however, that water has:::ers could lead to acre severe consequences; although it would ne expected that the probability of such events is very low.
Because of the continuing occurrence of water hamer events, the HRC staff has been evaluating available operating experience, actively discussing with nuclear stean suoply vendors and architect / engineering firus ways of reducing the. frequency and consequences of such events, ano utilizing technical consultants to more definitely examine water harmer pheno =:ena.
A copy of the report of our principal consultant, CREARE, is provided for your information in Enclosure I to this letter.
Mi, As a result of our efforts to cate, we believe that, water ha::;oers due te the rapid condensatica of steam in the feedwater lines of steam genera *wrs represent a sah v wnr. era.
xcoroingly, licensees of faciiities witn orrscs >
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e-o SEP 6 1977 Toledo Ed,ison Coccany destinghouse or Combustion Engineering design steam generators are being requested to take further actions, including possible design modifications, to assure an acceptably low risk to the health and safety of the public free such events. Your facility is not included in this category since it utilizes B&W steam generators which have not exhibited a propensity for water haarers based on operating experier.ce to date.
The staff will continue to monitor operating experience to assess the possible effects of water hamer on tne safety of nuclear power plants. While existing Technical Specifications contain reporting requirer. tents applicaole to water ha:mers, the staff has developed additional guidance regarding the tyce of events to be reportad.
',7 Specifically, all damaging water hamer events occurring in safety-related systems, or occurring in other systems that affect safety-related systeas, should be reported. A femat for the reports is provided in Enclosure 2 to this letter. Danaging water hamer events are those events that result in:
(a) daraage to pipe supports or pipe insulation, (b) pipe displacenent, or (c) failure of pipes or components.
Approved by GAO, B-180225 (20072), clearance expires July 31, H30.
Approval was given under a blanket clearance specifically for identified generic proolens.
Sincerely, Origin 21 stened Sf John F. Stulz John F. Stolz, Chief Light Water hactors Branch #1 Division of Project !!anagement
Enclosures:
1.
Report by CREARE on Water Hassaer Phenomena-2.
Fomat for Report 0
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M Toledo Edi, son Company ces: Donald H. Hauser, Esq.
The Cleveland Electric Illuminating Coepany P. O. Box 5000 Cleveland, Ohio 44101 Gerald Charnoff Esq.
Shaw, Pittman, Potts and Trowbridge 1800 M Street, N. W.
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Washington, D. C.
20036 Leslie Henry, Esq.
Fuller, Seney, Henry and Hodge 300 Madison Avenue Toledo, Ohio 43604
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