ML19330C042
| ML19330C042 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 08/05/1980 |
| From: | NRC OFFICE OF THE EXECUTIVE LEGAL DIRECTOR (OELD) |
| To: | Sholly S AFFILIATION NOT ASSIGNED |
| Shared Package | |
| ML19330C040 | List: |
| References | |
| ISSUANCES-SP, NUDOCS 8008070456 | |
| Download: ML19330C042 (1) | |
Text
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O Sholly Interrogatory SER 10 Page Cl-14 discusses a pending schedule for implementation of automatic closure of the PORY on low pressure. Will such a requirement be implemented by the Licensee before Restart? If not, why not?
RESPONSE
i The pressurizer PORV at TMI-l is designed to automatically close at reactor system pressures of less than 2450 psia.
In addition, a block valve upstream o'f the PORY is also provided as a backup means of isolation.
Fol' lowing a small break LOCA the operator is instructed to immediately close the block valve. This action would terminate water loss from the system in the event that the LOCA was produced by a stuck open PORY. As discussed on page Cl-14 of the staff SER for TMI-l restart, the NRC B&O Task Force recommended that a system which will cause the block valve to close when the RCS pressure has decreased below a preset pressure be installed at all B&W plants. This system is not required to be installed before restart.
As discussed in Section' II.X of the TMI-2 action plan and as further clarified in a letter from D. Eisenhut, NRC, to all operating reactor licensees.
May 7, 1930, the.decis, ion to implement the automatic block valve will be delayed pending the results of studies of inadvertant PORV' actuation
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probability to confirm that the system is necessary. Metropolitan Edison is required to complete the. probability studies by January 1,1981.
Analyses by B&W indicate, however, that the core will be adequately cooled in the event that the.PORY sticks open even if the operator fails to close the block valve.' The.NRC staff will therefore, not require that the automatic closure system be installed unless the studies described show that overall plant safety will be increased.
8008070 'f6 6
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