ML19296C346
| ML19296C346 | |
| Person / Time | |
|---|---|
| Site: | Vermont Yankee File:NorthStar Vermont Yankee icon.png |
| Issue date: | 02/08/1980 |
| From: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | Rich Smith VERMONT YANKEE NUCLEAR POWER CORP. |
| References | |
| NUDOCS 8002250631 | |
| Download: ML19296C346 (1) | |
Text
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o UNITED STATES E ' y
,,g NUCLEAR REGULATORY COMMISSION r
REGION I
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O 631 PARK AVENUE s
KING OF PRUSSIA, PENN3YLVANIA 19406 February 8,1980 Docket No. 50-271 Vermont Yankee Nuclear Power Corporation ATTN:
Mr. Robert L. Smith Licensing Engineer 25 itesearch Drive Westborough, Massachusetts 01581 Gentlemen:
The enclosed IE Bulletin No. 80-04 is forwarded to you for information. No written response is required.
If you desire additional information regarding this matter, please contact this office.
Sincerely, M
n Boyce H. Grier Director
Enclosures:
1.
List of Recently Issued IE Bulletins CONTACT:
D. L. Caphton (215-337-5253) cc w/encls:
W. F. Conway, Plant Superintendent Ms. J. Abbey, Technical Secretary Mr. J. E. Griffin, President 8002250 Ql
ENCLOSURE 1 UNITED STATES SSINS No.:
6820 NUCLEAR REGULATORY COMMISSION Accessions No.:
OFFICE OF INSPECTION AND ENFORCEMENT 7910250504 WASHINGTON, D.C.
20555 IE Bulletin No. 80-04 Date: February 8, 1980 Page 1 of 3 ANALYSIS OF A PWR MAIN STEAM LINE JREAK WITH CONTINUED FEEDWATER ADDITION Description of Circumstances:
Virginia Electric and Power Co. submitted a report to the Nuclear Regulatory Commission dated September 7, 1979 that identified a deficiency in the original analysis of containment pressurization as a result of reanalysis of steam line break for North Anna Power Station, Units 3 and 4.
Stone and Webster Engineering Corporation performed a reanalysis of containment pressure following a main steam line break and determined that, if the auxiliary feedwater system continued to supply feedwater at runout conditions to the steam generator that had experienced the steam line break, containment design pressure would be exceeded in approximately 10 minutes.
The long term blowdown of the wate" supplied under runout conditions by the auxiliary feedwater system had not been considered in the earlier analysis.
On October 1, 1979, the foregoing information was provided to all holders of operating licenses and construction permits in IE Information Notice No. 79-24. The Palisades facility did an accident analysis review pursuant to the information in the notice and discovered that with offsite power available, the condensate pumps would feed the affected generator at an excessive rate.
This excessive feed was not considered in the analysis for the steam line break accident.
On January 30, 1980, Maine Yankee Atomic Power Company informed the NRC of an error in the main steam line break analysis for the Maine Yankee plant.
During a review of the main steam line break aralysis, for zero or low power at the end of core life, the licensee identified an incorrect postulation that the startup feedwater control valves would rr. main positioned "as is" during the transient.
In reality, the startup feetwater ;ontrol valves will ramp to 80% full open due to an override signal resulting from the low steam generator pressure reactor trip signal.
Reanalysis of the event shows the opening of the startup valve and associated high feedwater addition tc the affected steam generator would cause a rapid reactor cooldown and resultar.t return-to power, a condition outside the plant design basis.
Actions to be Taken by the Licensee:
ForallpressurizedwaterpowerreacE DUPLICATE DOCUMENT reactors listed in Attachment 1:
Entire document previously entered into system under:
ANO No. of Pages:
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