ML19339B323
| ML19339B323 | |
| Person / Time | |
|---|---|
| Site: | Yankee Rowe |
| Issue date: | 06/08/1976 |
| From: | Johnson W YANKEE ATOMIC ELECTRIC CO. |
| To: | NRC COMMISSION (OCM) |
| References | |
| WYR-76-74, NUDOCS 8011060743 | |
| Download: ML19339B323 (2) | |
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YANKEE ATOMIC El.ECTRIC COMPANY urR 16-ra Wh 20 Turnpike Road Westborough, Massachusetts 01581 Y~auxus
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e June 8, 1976
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References:
(a) Docket 50-29 License DPR-3 R
Y Q (b) USNRC letter to YAEC, dated 6/7/76 6
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Dear Sir:
Reference (b) requested Yankee Atomic Electric Company to reassess the adequacy of the reactor vessel supports in light of a newly identified loading phenomena.
This new loading was observed as a result of improved analytical techniques which allow time dependent forces in the reactor vessel and reactor shield cavity to be calculated.
Yankee has been studyjna this issue for several months.
Part of this study has been the fuadir' probability study of a commercial rea coolant system to determ
._ relative probability of a failure of t.
reactor coolant systeu et t:e location necessary to produce the loadings discussed in Reference (b).
The resnits of this study, which are in final draft form, show that the probability of the specific break is four to five times lower than the overall probability of a reactor coolant piping design basis rupture.
Based on this low probability, and the design bases specified for the Yankee Nuclear Power Station, we arc of the opinion that the reactor vesst.1 support reassessment falls under the backfitting rule of 10CFR50.109.
Our present estimate is that two months will be required to review the probability study.
When that review is finished, we propose to meet with you, discuss the issue further, and assecs, at that time, the future course of action necessary to address your ccncerns in this matter.
We trust this information will be satisfactory, however, if you desire additional information, please feel free to contact us.
Very truly yours, YANKEE ATOMIC ELECTRIC COMPANY gg
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r W. P. Johnson Vice President 510e ugf p
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U.S. NUCLE An HECULAToRT AMISSioN DOCKET NUMBE R vv so-z9 NBC DISTRIBUTION ron PART 50 DOCKET MATERIAL FROM:
Yankee Atomic Elec Co oATE oF DOCUMENT TO: NRC 6-8-76 Westborough, Mass W P Johnson DATE RECEIVEo 7 14-76 i4LE TT E n ONoTonizEo enoe NeuT r onu NUusEn or CoriEs nECE vED EoniceNAL WUNC LAS$1FIE D OCory one signed DESCHieTeoN ENCLOSU R E
- Ltr re our 6-7-76 Itr.... furnishing info Concerning reacect vessell supports........
MNT MME:
Yankee Rowe DISTRIBUTION FOR REACTOR VESSEL SUPPORT INFO FOR OPERATING REACTORS PER MR. TRAMMELL 7-12-76 SAFETY FOR ACTION /INFORMATION
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