ML19209B103
| ML19209B103 | |
| Person / Time | |
|---|---|
| Site: | Midland |
| Issue date: | 08/13/1979 |
| From: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Howell S CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| References | |
| NUDOCS 7910090174 | |
| Download: ML19209B103 (1) | |
Text
k UNITED STATES
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8 NUCLEAR REGULATORY COMMISSION n
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aE REGION 111
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799 ROOSEVELT ROAD GLEN ELLYN. ILLINOls 60137 Docket No. 50-329 Docket No. 50-330 AUu,1 e uts Consumers Power Company ATTN:
Mr. Stephen H. Howell Vice President 1945 West Parnall Road
- Jackson,
'9201 Gentlemen:
The enclosed IE Bulletin No.
-21 is forwarded to you for information.
No writtea response is required.
If you desire additional information regarding this matter, please contact this office.
Sincerely, James G. Keppler
~~
Director
Enclosures:
8 1.
IE Bo'.letin No. 79-21
' IE Bulletins Issued 2.
List in the Last 6 Months cc w/enels:
Central Files L
'etor, NRR/DPM Dit: : tor, NRR/ DOR PDR Local PDR NSIC TIC Ronald Callen, Michigan Public Fervice Commission Dr. Wayne E. North Myron M. Cherry, Chicago 1116 012 7910090 4
Accession No:
7908090193 SSINS No:
6820 UNITEC STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
_20555 August 13, 1979 IE Bulletin No. 79-21 TEMPERATURE EFFECTS ON LEVEL MEASUREMENTS Description of Circumstances:
On June 22, 1979, Westinghouse Electric Corporation reported, to NRC, a potential substantial safety hazard under 10 CFR 21.
The report, Enclosure No.1, addresses the et rect of increased containment temperature on the reference leg water column and the resultant effect on the indicated steam gent:rator water level.
This effect would cause the indicated steam generator level to be higher than the actual level and could delay or prevent protection signals and could, also, provide erroneous information during post-accident monitoring.
Enclosure h;. 1 addresses only a Westinghouse steam generator reference leg water column; however, safety re"ted liquid level measuring systems utilized on other steam generators and.eactor coolant systems could be affected in a similar manner.
Actions To Be Taken By Licensees:
For all pressurized water power reactor facilities with an operating license:*
1.
Review the liquid level measuring systems within containment to determine if the signals are used to initiate safety actions or are used to provide post accident monitoring information.
Provide a description of systems that are so employed; a description of the type of reference leg shall be included, i.e., open column or sealed reference leg.
2.
On those systems described in Item 1 above, evaluate the effect of post-accident ambient temperatures on the indicated water level to determine any change in indicated level relative to cctual water level.
This evaluation must include other sources of error including the effects of varying fluid pressure and flashing of reference leg to steam on the water level measurements.
The results of this evaluation should be presented in a tabular form similar to Tables 1 and 2 of Enclosure 1.
Review all safety and control setpoints derived from level signals $o verify 3.
that the setpoints will initiate the action required by the plant safet analyses throughout the range of ambient t.
instrumentation, including accident 1" these setpoints.
DUPLICATE DOCUMEST-ntire document Previously entered r
" Boiling water reactors have been request into system under:
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hh NRC to provide similar information.
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June 22,1979 NS-TM-2104 Mr. Victor Stello Director, Office of Inspection and Enforcement U.S. Nuclear Regulatory Comission East West Towers Building 4350 East West Highway Bethesda, Mary 1rnd 20014
~
Dear Mr. Stello:
Subject:
Steam Generator Water Level This is to confirm my telephone conversation of June 21,1979 wi.h Mr.
Norma C. Moseley, Director, Division of Reactor Operation and Insoec-tion and Mr. Samuel E. Bryan, Assistant Director for Field Coordination.
In that conversation, I reported that Westinghouse had informed its utility customers of corrections that should be applied to indicated steam generator water level and reconriended that they incorporate those ccrrecticns in the steam generator low water levei protection system setpoints and emergency operating procedures for operating plants as appropriate.
High energy line breakc inside containment can result in heatup of the steam generator level measurement reference leg.
Increased reference leg water column temperature will result in a decrease of the water column density with a consequent appcrent increase in the indicated steam generator water level (i.e., apparent level exceeding actual level). This potential level bias could res.it in delayed protection signals (reactor trip and auxiliary feedwater initiation) which are based on low-low steam generator water level.
In the case of a feedline rupture, this adverse environment could be present and could delay or prevent the primary signal arising from declining steam gen 6rator water level (low-low steam generator level).
The following is a list of backup signals available in those Westinghouse plants which take credit in their Final Safety Analysis Reports for steam generator water level trip with
_ an adverse containment environment:
overtemperature delta T; high pressurizer pressure; containment pressure and safety injection.
For other high energy line breaks which i
bias to the steam generator water le DUPLICATE DOCUMENT level does not provide the primary t would not interfere with needed prot Entire document previously entered into system under:
h
}f ANO No. of pages:
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