ML19339C033
| ML19339C033 | |
| Person / Time | |
|---|---|
| Site: | Midland |
| Issue date: | 11/03/1980 |
| From: | Fiorelli G NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Jackie Cook CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| References | |
| NUDOCS 8011170181 | |
| Download: ML19339C033 (1) | |
Text
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UNITED STATES 0,,
NUCLEAR REGULATORY COMMISSION
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REGION 111 5
j 799 ROOSEVELT ROAD g
GLEN ELLYN, ILLINOIS 60M7
.es NOV 3_1980 0,
8 Ei w
.h N3 Docket No. 50-329 m(
Ms Docket No. 50-330 S'3"
'M Mz3 N9, V tr Consumers Power Company
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ATTN:
Mr. James W. Cook.
F3 N,5 Vice President h
a Midland Project 1945 West Parnall Road Jackson, MI 49201 Centlemen: -
Thank you for your inte. rim report dated October 10, 1980, pursuant to 5
10 CFR 50.55(e) regarding small break / reactor coolant pump operation interaction. We will review your final report on this matter upon receipt.
Your cooperation with us is appreciated.
Sincerely,
) C .r W l
- O G. Fiorel 1, Chief
~
Reactor Construction and Engineering Support Branch l
CC: Director, RCI/IE Director, AEOD Chief, OEB/MPA IE Files 3
i cc w/ltr dtd 10/10/80:
j Central Files PDR 1
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Ronald Callen, Michigan Public Service' Commission Myron M. Cherry, Chicago l
8 011170 l${ -
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Consun1ers POW'Cr
.iernes w cook Company m, ~a,.,. -w,u Generan omces 1945 West Parnett Road, Jackson, %chegan 49201 *(517)788 0640 October 10, 1980 Mr J G Keppler, Begicnal Director Office of Inspection and Enforcement US Huclear Regulatory Commission Region III 799 Roosevelt Road Glen Ellyn, IL 60137 MIDLA';D NUCLEAR PLANT -
UNIT NC 1, DOCKET NO 50-329 UNIT NO 2, DOCKET No 50-330 SMALL BREAK / REACTOR CCCLANT PUMP OPERATION INTERACTION FILE:
0.L.9.28 UFT:
73*10*01, 42*LO*01*20, 023h2(S) SERIAL:
9770
References:
S E 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 Howe-221-79; dated August 15, 1979
- 2) Serial Hove-271-79; dated October 19, 3979
- 3) Serial Hove-25-80; dated' February 8,1960 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 reactor coolant pumps during certain primary system high void fraction conditions.
Small break LOCA analyses conducted following the TIG 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 plants as a result of this analysis were to modify operating procedures to require prompt manual trip of the RCPs if the low pressure ESFAS setpoint was reached.
Long term requirements specified by IE Eulletin 79-05C included the incorporation of safety grade automatic RCP trip circuitry initiated to assure pump trip for events necessary based upon the existing analyses.
The Midland design vill be modified to incorporate safety grade automatic RCP trip circuitry. Initiation of pump trip vill be based upon an RCS pressure as lov as possible without precluding actuation where required.
The lower the actuation pressure, the fever non-LOCA events vill result in a pump trip. Quantification of this setpoint avaits further analytical work ongoing by ELW. At a minimum, it is desired that the final setroint be below the existing low pressure ESFAS value (1500 psig).
OCT "
GU gologooroi
1 2
Serial:
9770 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 Consum.ers Power Company is therefore participating in a sluggish manner.
generic program to develop more accurate computer models to predict B&'n' It is hoped that these more sophisticated post small break LOCA conditions.
analyses, coupled with results from f uture LOPI tests, will be able to justify continued RCP operation for all transient conditions.
The engineering, procurement and construction activities are scheduled to 30, 1981.
support completion of the required modifications by November either interim or final, vill be submitted on or before Another report, May 30,19cl.
WRE/1r CC: Director of Office of Inspection
& Enforcement Att Mr Victor Stello, USNRC (15)
Director, Of fice of Management Infcr ation & Program Control, USNRC (1)
R J Cook, NRC Resident Inspector Midland Nuclear Plant Site (1)
,