ML19296C339
| ML19296C339 | |
| Person / Time | |
|---|---|
| Site: | Seabrook  |
| Issue date: | 02/08/1980 |
| From: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | Tallman W PUBLIC SERVICE CO. OF NEW HAMPSHIRE |
| References | |
| NUDOCS 8002250618 | |
| Download: ML19296C339 (1) | |
Text
, naa T fC-jo UNITED STATES E
g,,
NUCLEAR REGULATORY COMMISSION g.g ] gg -[g c
REGION I o, 5de.) I 631 PARK AVENUE
%,
- O*****,o#
KING OF PRUSSIA, PENNSYLVANIA 19406 February 8,1980 Docket Nos. 50-443 50-444 Public Service Company of New Hampshire ATTN:
Mr. W. C. Tallman President 1000 Elm Street Manchester, New Hampshire 03105 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, n
Boyce H. Grier Director
Enclosures:
1.
List of Recently Issued IE Bulletins CONTACT:
D. L. Caphton (215-337-5253) cc w/encls:
John DeVincentis, Project Manager 8002250 6/2'
ENCLOSURE 1 UNITED STATES SSINS No.:
6820 NUCLEAR REGULATORY COMMISSION Accessions No.:
OFFICE OF INSPECTION AND ENFORCEMENT 7910250304 WASHINGTON, D.C.
20555 IE Bulletin No. 80-04 Date: February 8, 1980 Page 1 of 3 ANALYSIS OF A PWR MAIN STEAM LINE BREAK 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 mirutes.
The long term blowdown of the water supplied under runout conditions by.he 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 analysis, for zero or low power at the end of core life, the licensee identified an incorrect postulati n that the startup feedwater control valves would remain positioned "as is" during the transient.
In reality, the startup feedwater control 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 to the affected steam generator would cause a rapid reactor cooldown and resultant return-to power, a condition outside the plant design basis.
Actions to be Taken by the Licensee:
For all pressurized water power react DUPLICATE DOCUMENT reactors listed in Attachment 1:
Entire document previously entered into system under:
ANO No. of pages: