ML19209B087
| ML19209B087 | |
| Person / Time | |
|---|---|
| Site: | Zion File:ZionSolutions icon.png |
| Issue date: | 08/13/1979 |
| From: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Brian Lee COMMONWEALTH EDISON CO. |
| References | |
| NUDOCS 7910090151 | |
| Download: ML19209B087 (1) | |
Text
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- pskanacyg'o UNITED STATES E ' g [a e NUCLEAR REGULATORY COMMISSION g
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799 ROOSEVELT ROAD
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GLEN ELLYN,ILLINOls 6o137 o
Docket No. 50-295 Docket No. 50-304 Commonwealth Edison Company h@l AITN:
Mr. Byron Lee, Jr.
Vice President Post Office Box 767 Chicago, IL 60690 Gentlemen:
Enclosed is IE Bulletin No. 79-21 which requi.as action by you with regard to your PWR power reactor facilities with an operating license.
Should you have any questions regarding this Bulletin or the actions required by you, please contact this office.
Sincerely, (b ?&
ames G. Keppler /,
Director
Enclosures:
1.
List of IE Bulletins Issued in the Last 6 Months cc w/encls:
Mr. N. Wandke, Plant Superintendent Central Files Director, NRR/DPM Director, NRR/ DOR,
PDR Local PDR NSIC TIC Mr. Dean Hansell, Office of Assistant Attorney General 1115 290 jg/
7910090
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Accession No:
7908090193 SSINS No:
6820 UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFCRCEMENT WASHINGTON, D.C.
20555 August 13, 1979 IE Bulletin No. 79-21 TEMPERATURE U FECTS ON LEVEL HEASUREMENTS Description of Circumstances:
On June 22, 1979, Westinghouse Electric Corporation reported, to NRC, a potential sub!,tantial safety hazard under 10 CFR 21.
ihe report, Enclosure No.1, addresses the effect of increased containment temperature on the reference leg water column and the resultant effe-t on the indicated steam generator water level.
This effect would cause the indicated steam generator level to be higha-than the actual level anc could delay or prevent protection signals and could, also, provide erroneous ir. formation during post-accident monitoring.
Enclosure No. 1 addresses only a Westinghouse steam generator reference leg water column; however, sa'ety re'.ated liquid level measuring systems utilized on other steam generators and reactor coolant systems could be affected in a similar manner.
Actions To Be Taken By Licensees:
For all pressurized water power reactor facilities with t_.1 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, neludad, i.e., open column or sealed reference leg.
2.
On those systems described in Item 1 above, evaluate the effect of post-accident ambient t'mperatures on the indicated water level to determine any change in indicated level relative to actual 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 rer its of this evaluation should be presented in a tabular form similar to Tab'.as 1 and 2 of Enclosure 1.
3.
Review all safety and control setpoints derived from level signals to verify that the setpoints will initiate the action required by the plant safety analyses throughout the range of amb't " ^ ' * * -~" " %
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instrumentation, including accident 1
<7 JUPLICATE DOCUMENT these setpoints.
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June 22,1979 NS-TMA-2ic4 Mr. Victor Stel
Director, Offiu.
' Wspection and Enforcement U.S. Nuclear Regulatory Comission East West Towers Building 4350 East Wes_t Highway Bethesda, Maryland 20014
Dear Mr. Stello:
Subject:
Steam Generator Water Level This is to confirm my telephone onversation of June 21, 1979 with Mr.
Norman C. Moseley, Director, Civision 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 reconmended that they incorporate those corre:tiens in the steam generator low water level protection system setpoints and emergency operating procedures for operating plants as appropria te.
High energy line breaks 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 apparent increase in the indicated stea.m generator ster level (i.e., apparent level exceeding actual level). This potential level bias could result 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 generator 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
' pres.orizer pressure; containment pressure and safe injection.
For other high energy line breaks which d'h, "' " - ~ 4 h r w - - g bias to the steam generator water le' JUPLICATE DOCD1 E.NT I
level does not provide the primary t1 would not interfere with needed prot' Entire document previously entered into system under:
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