ML20244B882
| ML20244B882 | |
| Person / Time | |
|---|---|
| Issue date: | 03/31/1982 |
| From: | Tedesco R Office of Nuclear Reactor Regulation |
| To: | Plessett M Advisory Committee on Reactor Safeguards |
| Shared Package | |
| ML20234E460 | List:
|
| References | |
| FOIA-87-40 ACRS-GENERAL, NUDOCS 8204220523 | |
| Download: ML20244B882 (1) | |
Text
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! 'n NUCLEAR REGULATORY COMMISSION
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en MJ9.Q,g QS FROM: Robert L. Tedesco, Assistant Director for Licensing }
Division of Licensing i
SUBJECT:
MARK III FROTH IMPINGEMENT LOADS ON THE HCU FLOOR In recent ACRS meetings, a question has been raised regarding the effects of the Mark III pool swell froth impingement on the, hydraulic control unit (HCU) modul es. The HCU floor is located approximately 20 feet above the surface of the pool and consists of both solid concrete and grating sections. The froth impingement load specification proposed by GE for the HCU floor (15 psid) was found to be unacceptable by the staff, and an alternate space-dependent load specification has been specified in our acceptance criteria. Each of the Mark III plants will be required to evaluate the suppression pool dynamic loads in accordance with the staff's acceptance criteria, which will include the structural analysis of the HCU floor and other structures and piping located above the pool.
The components of the HCU modules are designed to a variety of standards, depend-ing on the function, and are not environmentally qualified. Since the froth impingement load occurs at about 1.5 to 2.0 seconds after a DBA-LOCA, at which time control rod insertion is less than 90% complete, there is a potential for an incomplete scram due to (1) froth impingement on the bottom o'f the HCU modules '
located on grating could cause a failure of the accumulator injection line, or (2) wetting of the HCU module might cause a failure of the valve on the accumulator injection line.
We are currently pursuing this matter with the Mark III applicants and we will keep you informed of our progress.
Dc0 Robert L. Tedesco, Assistant Director ,
for Licensing )
Division of Licensing )
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