ML20024G127
| ML20024G127 | |
| Person / Time | |
|---|---|
| Site: | Monticello  |
| Issue date: | 05/20/1976 |
| From: | Ziemann D Office of Nuclear Reactor Regulation |
| To: | Mayer L NORTHERN STATES POWER CO. |
| References | |
| NUDOCS 9102070558 | |
| Download: ML20024G127 (3) | |
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MAY l' 01976 yckeeno.50-263 tJ
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ATTNI. Mr. L. 9. Mayer, Nasager Woclear Support Services Winn[N(selletMatt:SthFleer 414 eapolie Minnesota-HA01 r. *. a
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Gentlemes RE: MONTICELLO NUCLEAR CENERATIFC PLANT A recent investigation at a BWR-4 plant identified a design deficiency that could potentially disable the long ters core and containment cooling system following a postulated loss-of-coolant accident (LOCA). This design deficiency involves the potential for RER (LPCI) pumps to operate in excess of dssign flow (runout) during a postulated LOCA. Operation of the RHR (LPCI) pumps under this condition could result la damage to the pumps due to cavitation and/or motor overload.
Pump runout conditions could occur in situations where the RRR (LPCI) pumps discharge to flow paths with too little system flow resistance. The following examples describe situations that could potentially result la RHR (LPCI) pump runout conditions and a subsequent reduction or loss of long teru heat removal capabilityt a.
For BWR-3 and SWR-4 plants with Loop Selection Logic Systens (LSLS), a single failure in the LSLS could result, fu (1) four LPCI pumps injecting into a broken recirculation loop, or (2) four LPCI pumps injecting into both recirculation loops simultaneously, with one loop broken.
In addition, operation with three pumps providing flow (one pump I
inoperable as allowed per Technical Specifications) to the l
unbroken loop may closely approach runout conditions.
b.
For EVR-3 and BWR-4 plants with the LPCI modification, the single failure of a recirculation loop discharge valve..to close could result in two LPCI pumps injecting,into the intact (unbroken) loop at flow rates in excess of design.
In addition, the two LPCI pumps which would normally P '
discharge into thesbroken recirculation loop may.also exceed design flow rates.
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You are therefore requested, withis 30 days of receipt of this letter, to sobett the followies informaties:
o An analysis of the abovementlemed or any other Petet.tict -
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RER (LPCI) peep ruseet situations which arG applicable to year feet!!ty te deseemise if less term heat removal
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capaht!!ty eeeld be impaired felicwing a LOCA.
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A schedule for making system design modifiestions if any
.g are meessoary.
A description of the testing program that will be used c.
to verify that the required design modifications:
(1) adequately protect the RBR (LPCI) pumps frt.a potential runout conditions, and (2) essure that LPCI systes core reflood performance is in accordance with the current ECCS analysis for your facility.
One signed original and 39 copies of your answer will be necessary.
This request for generle information was approved by CAO under a blanket clearance number 3-180225 (R0072); this clearance expires.kly 31, 1977 Sincerely, t
Oricinal Sicned by:
Denniu L. Ziecann Dennis L. Ziesann, Chief Operating Reactors Branch #2 Division of Deerating Reactors DISRIB'JTION NRC PDR JRBuchanan Local PDR ACRS (16)
Docket VStello ORB #2 Reading MHFletcher ERGoller JGuibert TJCarter OELD - Slevis OI6E (3)
DLZiemann RPSnaider RMdiggs (2)
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J Anthony Z. Roissan, Esquire cc Gerald Charnoff, Esquire Roisman, Kessler and Cashdan Shaw, Pittman, Potts and 1712 N Street, N. W.
4 Trowbridge 1800 M Street, N. W.
Washington, D. C.
20036 Washington, D. C.
20036
'lhe Environmental Conservation Library Arthur Renquist, Esquire Minneapolis Public Library Vice President - Law W, '
300 Nicollet Mall Nortnern States Power Company 414 Alcollet bb11 Minneapolis, Minnesota 55401 l
Minneapolis, Minnesota 55401 lloward J. Vogel, Esquire Legal Counsel 2750 Dean Parkway Minneapolis, Minnesota 55416 Mr. Steve J. Gadler 2120 Carter Avenue St. Paul, Minnesota 55108 l
Daniel L. Ficker, Esquire Assistant City Attomey Criminal Division 638 City llall St. Paul, Minnesota 55102 Mr. Kenneth Drugan a
Environmental Planning Consultant Office of City Planner li' Grace dullding 421 Wabasha Street i
St. Paul, Minnesota 55102 Sandra S. Gardebring, Esquire Special Assistant Attorney General Minnesota Pollution Control Agency 1935 W. County Road B2 4
Roseville, Minnesota 55113 a.
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