ML19338F544
| ML19338F544 | |
| Person / Time | |
|---|---|
| Site: | Midland |
| Issue date: | 10/10/1980 |
| From: | Jackie Cook CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| References | |
| 10CFR-050.55E, 10CFR-50.55E, 9770, IEB-79-05C, NUDOCS 8010200501 | |
| Download: ML19338F544 (2) | |
Text
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/ M Consumcis Wiler-F
!. 3 James W Cook 00 f~
Mce l>csident, AfsJ!and ovuject s
Genera'l of feces: 1945 West Paenall Road, Jackson, Michigan 49201 *(517) 788-0640
~ Oct'ober. 10,-1980 i-Mr J'G Keppler, Regional Director L
Office of Inspection and Enforcement US' Nuclear Regulatory Commission Region III 799 Roosevelt Road Glen Ellyn, IL 60137 MIDLAND NUCLEAR PLANT.-
UNIT NO 1, DOCKET No 50-329 UNIT NO 2, DOCKET NO 50-330 SMALL BREAK / REACTOR COOLANT PUMP OPERATION INTERACTION FILE:
0.h.9' 28 UFI:
73*10*01, h2*kO*0l*20., 02342(S) SERIAL:
9770
References:
S H Howell letters to J G Keppler; Midland Nuclear Plant; Unit No 1, Docket No 50-329; Unit No 2, Docket No 50-330; Small Break / Reactor Coolant Pump Operation Interaction:
- 1) Serial ' Hove-221-79; dated August 15, 1979
- 2) Serial Hove-271-79; dated October 19, 1979
- 3) Serial Hove-25-80; dated February 8,1980 This letter, as were the referenced letters, is an interim 50.55(e) report concerning a potentially unsafe situation with respect to the tripping of l.
reactor coolant' pumps during certain primary system high void fraction conditions.
-Small break LOCA analyses conducted following the TMI accident identified.a need to trip the RCPs promptly after breaks of specific sizes. - This action was necessary to eliminate the possibility of uncovering the core and-exceeding 10CFR50 Appendix K limits if the RCPs became: inoperable after the RCS reached high void fraction conditions.. Actions taken by the operating plantsias ~a result 1of this analysis were to modify operating procedures to l
require prompt' manual trip. of the RCPs 'if _the' low pressure ESFAS --setpoint was reached.
Long term requirements specified by IE Bulletin 79-05C included
'the.incerporation.of safety grade automatic RCP trip circuitry initiated to
' assure pump trip for events necessary based:upon the existing analyses.
. The' Midland des'ign vill 'be -modified to incorporate safety Grade automatic k.
RCP trip. circuitry. Initiation of pump trip will _be based-upon an RCS L
pressure as low 'as _ possible without precluding actuation _ where required.
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- The lover the(actuation pressure, the fever non-LOCA events vill result in
-a pump trip...Quantification.of this setpoint avaits further analytical work
- ongoing by:B&W. ~At'a minimum,-it isl desired that.the final setpoint be'below-the existing low pressure ESFAS value-(1500 psig).
soioso oSol:
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Serial:
0770-
. Requiring an RCP trip during any transient ~is not an. optimal solution since
'it results in plant conditions which respond to operator control in a more sluggish manner.. Consumers PowerJ Company is 'therefore-participating in a
'B&W generic: program to. develop more accurate computer models to predict postismall' break.LOCA conditions. It is hoped.that these more sophisticated
- analyses, coupled vith results from future LOFT tests, vill' be able to justify.
continued RCPJoperation 'for all: transient. conditions.
The engineering, procurement and construction activities are scheduled to support completion of the required modifi, cations by November 30, 1981.
Another report, either interim or. final, vill be submitted on or before Mgy 30, 1981.
WRB/lr CC: Director of Office of Inspection
& Enforcement Att Mr Victor Stello, USNRC (15)
Director, Office of Management Information & Program Control, USNRC (1)
R J Cook, NRC Resident Inspector Midland Nuclear' Plant Site'(1)-
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