NRC Generic Letter 1985-03
| ML031150576 | |
| Person / Time | |
|---|---|
| Issue date: | 01/02/1985 |
| From: | Eisenhut D Office of Nuclear Reactor Regulation |
| To: | |
| References | |
| GL-85-003, NUDOCS 8501290633 | |
| Download: ML031150576 (1) | |
1__.-.. e t norl
- A-dIudry 1Y o TO ALL BOILING WATER REACTOR LICE SEES AND APPLICANTS
Gentlemen:
SUBJECT: CLARIFICATION OF EQUIVALENT CONTROL CAPACITY FOR
STANDBY LIQUID CONTROL SYSTEMS (Generic Letter 85-03)
3 Paragraph (c) (4) of 10 CFR 50.62 states, in part:
Each boiling water reactor must have a standby liquid control system (SLCS) with a minimum flow capacity and boron content equivalent in control capacity to 86 gallons per minute of
13 weight percent sodium pentaborate solution.
The "equivalent in control capacity" wording was chosen to allow flexibility in the implementation of the requirement. For example, the equivalence can be obtained by increasing flow rate, boron concentration or boron enrichment.
The 86 gallons per minute and 13 weight percent sodium pentaborate were values used in NEDE-24222, "Assessment of BWR Mitigation of ATWS, Volumes I and II,"
December 1979, for BWR/4, BWR/5 and BWR/6 plants with a 251 inch vessel inside diameter. That different values would be equivalent for smaller plants was recognized in NEDE-24222:
The flow rates given here are normalized from a 251-inch-diameter vessel plant to a 218-inch-diameter vessel plant, i.e., the 66 GPM control liquid injection rate in a 218 is equivalent to 86 GPM in a 251. This is done to bound the analysis...(pp. 3-12)
The important parameters to consider in establishing equivalence are vessel boron concentration required to achieve shutdown and the time required to achieve that vessel boron concentration. The minimally acceptable system should show an equivalence in these parameters to the 251 inch diameter vessels studied in NEDE-24222.
There are no reporting requirements associated with this generic letter.
Sincerely, Original signed by Darrell G. EisenhUt Darrell G. Eisenhut, Director Division of Licensing Office of Nuclear Reactor Regulation OELD 144 VWShields ORAL 1/23/85/
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