05000289/LER-1980-012-01, /01T-0:on 800627,during Review of Environ Qualification of Equipment Required to Operate During Main Steam Line Break Per IE Bulletin 79-01B,found That post- Accident Analysis Exceeded Previous Figures

/01T-0:on 800627,during Review of Environ Qualification of Equipment Required to Operate During Main Steam Line Break Per IE Bulletin 79-01B,found That post- Accident Analysis Exceeded Previous Figures

ML19320C254
Person / Time
Site:	Crane
Issue date:	07/11/1980
From:	Mitchell D METROPOLITAN EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML19320C252	List: 05000289/LER-1980-012, Forwards LER 80-012/01T-0 05000289/LER-1980-012-01, /01T-0:on 800627,during Review of Environ Qualification of Equipment Required to Operate During Main Steam Line Break Per IE Bulletin 79-01B,found That post- Accident Analysis Exceeded Previous Figures
References
IEB-79-01B, IEB-79-1B, LER-80-012-01T, LER-80-12-1T, TLL-334, NUDOCS 8007160526
Download: ML19320C254 (2)

LER-1980-012, /01T-0:on 800627,during Review of Environ Qualification of Equipment Required to Operate During Main Steam Line Break Per IE Bulletin 79-01B,found That post- Accident Analysis Exceeded Previous Figures

Event date:
Report date:
2891980012R01 - NRC Website

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g,during a main steam line break per IE Bulletin 79-OlB it was determined that I

, o,,, l post accident pressure and temperature in the Intermediate Buildine exceeded the go,,,gprevious analysis figures. The unit is presently in a long term cold shutdown I

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NARRATIVE

REPORT TMI-I LER 80-012/01T-0 I.

EXPLANATION OF OCCUPRENCE As part of the environmental qualification of equipment required to operate during a main steam line break stated in IE Bulletin 79-OlB, a review of the Analysis of the Intermediate Building Environment following a Postulated Main Steam Line Break was initiated. This analysis in report form was submitted by Nuclear Services Corporation (NSC) to Met-Ed on July 5, 1973.

The analysis was based upon the steam lines containing saturated steam instead of super heated steam. The energy level after an accident will be higher than used in the existing report. An investigation of the free venting area was also undertaken because the report by NSC did not identify where the venting areas existed. This analysis assumed that there is 167 square feet of venting area in the Intermediate Building.

The only known venting areas that would be available in the event of a main steam line break are the double doors opening out into the Turbine Building on el. 305 and the grating used for the reactor purge system on el. 322.

The double doors will be forced open by the differential pressure developed as a result of the main steam line break. This venting area is 75 square feet.

The intake grating for the reactor purge system is within a 24 gauge galvanized steel enclosure. The differential pressure caused by the event could collapse the enclosure over the grating eliminating 87 square feet of venting area.

II.

CAUSE OF THE OCCURRENCE This event was due to a reanalysis performed as a part of the work required by IE Bulletin 79-OlB.

Basing the analysis on super heated steam and with a smaller venting area, there will be higher post accident pressure and temperature than postulated by the existing report.

This will affect the environmental qualification requirements for safety related equipment in the Intermediate Building.

III.

CIRCUMSTANCES SURROUNDING THE OCCURRENCE The unit is in a long term cold shutdown condition with core cooling being provided by the Decay Heat System. This precludes a main steam line break from occurring.

IV.

CORRECTIVE ACTION TO BE TAKEN TO PREVENT RECURRENCE The Intermediate' Building environment following a main steam line break will be analyzed using super heated steam and the proper venting area. The new environmental data will be used in evaluating qualification of safety related equipment in response to Bulletin 79-013.