ML19309B284
| ML19309B284 | |
| Person / Time | |
|---|---|
| Site: | Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png |
| Issue date: | 02/26/1980 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML19309B283 | List: |
| References | |
| TASK-05-13, TASK-5-13, TASK-RR NUDOCS 8004030366 | |
| Download: ML19309B284 (10) | |
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SAFETY EVALUATION REPORT STEAM GENERATOR WATER HAMMER HADDAM NECK PLANT DOCKET NO. 50-213 L
Steam generator water hammer has occurred in certain nuclear power plants as a result of the rapid condensation of steam in a steam i
generator feedwater line and the consequent acceleration of a slug of water which upon impact within the piping system causes undue l
stresses in the piping and its suppcrt system.
The significance of these events varies from plant to plant. Since a total loss of feecwater could affect the ability of the plant to cool down after a reactor shutdown, the NRC is concerned about these events occurring, even though an event with potentially serious consequences is unlikely to happen.
Because of the continuing occurrence of water hammer events, the NRC, in September 1977,' informed all PWR licensees that water har:ner events due to the rapid condensation of steam in the feed-water 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 assur hat an acceptably low risk to public safety due to such events is maintained. Accordingly, these licensees were requested to sub.it proposed hardware and/or procedural modifications, if '
any, v.ich would be necessary to assure that the feedwater lines and feedrings remain filled with water during normal as well as transient operating conditions. At the same time, the NRC provided each PWR licensee with a copy of its consul: ant's report, "An Evaluation of PWR Steam Generator Water Hamner," NUREG-0291, Tne principal feature of the Haddam Neck Plant that reduces the potential for steam generator water hammer is the favorably short length of feecwater piping adjacent to the steam generator.
It consis s of a downward turning elbow connected directly to the no::le of the steam generator.
2.2 EVAL *,:ATION C.:r consultant, EG&G Idaho, Inc., precared :ne attached evaluation cf s: ear generator water ha=er i: :ne Haddt-Neck Diant as part c' c;r te:hnical assistance progra.
. Letter 'ror J. A.
Dearien,
EG&G,
- R E. Tiller, DOE, dated Dece ::er 25,197:.'
We nave reviewed
- nis report together with tne licensee's su: 'ttals listed under i te-4.0 8004030 366
3.0 CONCLUSION
_a Based on our knowledge of water hamer phenomena, and our review of the licensee's responses and the enclosed evaluation report, we concur with our consultants' conclusion that the potential for damaging steam generator water hanner is sufficiently low to permit continued operation of this facility.
However, even though steam generator water hacrer is not likely to occur, the licensee should be vigilant and monitor for water hamers that might impose signifi-cant stresses on the piping systems or their supports. We will continue to monitor reports from the licensee for indications of possible water harrer.
If such indications appear in the future, this matter will be reexamined and may result in additional require-ments to reduce the probability of steam generator water hammer at this facility.
We have concluded that steam generator water hammer is not likely to occur at this facility and, therefore, we find no undue risk
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to the health and safety of the public as a result of the continued operation of the Haddam Neck Plant.
1.0 REFERENCES
4.1 D. C. Switzer, Connecticut Yankee Atomic Power Compant (CY),
lettar to R. A. Purple, flRC, "Haddam Neck Plant, Secondary Syste-Fluid Flow Instability," July 15, 1975.
4.2 R. H. Graves, OY, ietter t: J. P. O'Reilly, NRC, " Reportable Occurrence - Cadated Repor: - Previous Report Dates 7-27-76 and 3-27-76," November 17, 1976.
4.3
- 3. C. Switzer, CY, letter o A. Schwencer, URC, "Haddam Neck
?lar.:, Steat Generator Water Hammer," January 3,1978.
4.4
'. l. G. Counsil, CY, letter o D. Z. Ziemann, NRC, "Haddam Neck
?lant Additional Information - Steam Generator Water Hammer,"
dated Novemoer 26, 1979.
4.5 J. B. Block, e; al, An Evaluation of PWR Steam Generator Water
-iam er, Creare, :n:., NURE3-0291 (Decemoer 1976) 4.6
.:. E. Benne::, Waterna mer in Steam Generator Feedwater Lines,
.ies-ir.gnouse Tecnn: cal Bul;e:1r., 35D-T5-75-7 (June 10, 1975).
- 1 e:
-::a:n ent:
E3;3 is :e :a:ed 12/21 i
EGsG usano, une.
P O. Box 7625
. Idaho Falts. Ic.a.% r.Ac.
Decenber 28, 1979
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Mr. R. E. Tiller Director Reactor Operations and Programs Oivision Idaho Operations Office - COE Idab Falls, ID 83401 HADDAM HECK (C0llNECTICUT YA'iKEE) PCNER STATION STEAM GENERATOR WATER HAMliER TECH!{ICAL EVALUATI0ii (AE257) - JAD-261-79 Ref:
J. A.
Dearien Ltr to R. E. Tiller,
JAD-225-79, PWR Steam Generator Water Ha.=nr Reviews (A5257), Noveroer 8,1979
Dear Mr. Tiller:
Tne attachnent cocpletes the assessnent of tne effectiveness of the existing mans to reduce t..e poter.:ial for stean generator water hariner at the Haddam lieck Fower Statier..
The assesst.)ent has shcwn that conditior.s concutive to steam generator water har.ner have occurred thrcugh August 1979 at the Haddam Neck Plant and it is certain that no wa:er hamer events have been ob '
j served since 1975.
He.vever, infer aticn is not availaole to confirm wnether tne several water hammer ever.ts puroorted to have occurred prior to 1975 were steam generator water ha:rers or feedwater line transients caused by abrupt valve or pamp action. The concitions conducive to steam generator water harer are encountered during norm 1 operating transients and during stanuo and shutdown.
Such conditions would also be expected in the future during the normal and accident operating situations addresse: in this review.
Based on the operating history since 1975, we have concluded that the po-tential for damaging stean genera:or water har.er is sufficiently low to pen.it continued operation of tnis facility.
This transmittal constitutes completion of tne SER for the Hadcam lieck (Connecticut Yankee) Plant, Task A5257 on the Miles ene Chart in the reference.
very truly yours, cap-! F-nd Gy T, A. &n:::n J. A.
Dearien,
Manager Ocde Assessren: and A::lica:icas Program L'E : n Attachmen :
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S. D. MacKay, NE~
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