ML19338D390
| ML19338D390 | |
| Person / Time | |
|---|---|
| Issue date: | 09/27/1979 |
| From: | Satterfield R Office of Nuclear Reactor Regulation |
| To: | Baer R, Parr O, Stolz J Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML19338D384 | List: |
| References | |
| IEB-79-21, NUDOCS 8009230086 | |
| Download: ML19338D390 (2) | |
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ENCLOSURE 5 8
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UtJITED STATES NUCLEAR REGULATORY COMMISSION l,.
j WASHINGTON, D. C. 20555
,f SEP 2 71979 1
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MEMORANDUM FOR: John F. Stolz, Chief, Light Water Reactors Branch #1, DPM Robert L. Baer, Chief, Light Water Reactors Branch #2, DPM Olan D. Parr, Chief, Light Water Reactors Branch #3, DPM Lester Rubenstein, Acting Chief, Light Water Reactors Branch f4, DPM FROM:
Rodney M. Satterfield, Chief, Instrumentation & Control Systems Branch, DSS p
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SUBJECT:
FOLLOW-UP ACTION WITH NEAR TEPfi OL APPLICANTS ON CONCERNS RAISED IN IE BULLETIN 79-21 The enclosed generic question should be forsarded to the fiear Term OL Applicants so that the concerns raised in IE Bulletin 79-21 may be addressed in our review of level measurement systems.
Please advise if you have additional questions on this matter, Rodne{y M. Satte field, Chief i
Instrumentation & Control Systems Branch, DSS
Enclosure:
As stated
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H. Denton F, Schroeder D. Eisenhut R. Denise V Moore G, Lainas D. Tondi T. Dunni.ng I S
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ENCLOSURE
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LEVELMENUREMENTERRORSDUETOENVIRONMENTALTEMPERATUREEFFECTSON
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LEVEL INSTRUMENT REFERENCE LEGS
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On June 72, 1979, Westinghouse Electric Corporation reported to NRC, a potential safety hazard under.10 CFR 21." This' report addresses errors 1_
generated in the ste'am generator level indication sensors following.
high energy pipe break accidents inside containment..Further; the -
report implies that previous analyses 'of peak containment tempecatdrac and pressure may.have been nonconservative.
Breaks of this type can result in heatup of the steam generator level measurement reference leg resulting in a decrease of the water column density with a consequent increase in the indicated steam generator water level (i.e., indicated level exceeding actual level)1 IE Bulletin 79-21 includes further information on this problem and addresses appropriate actions which are to be taken by licensees of operating plants.
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Applicants for an operating license are requested to submit a response to the following questions and to revise their safety analysis report consistent with. this response?c~-.(. T ?
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Describe the liquid level measuring systems within containment that are used to initiate' safety actions or are used to provide post -
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accident conitoring information. Provide a description of the type' of reference leg used i.e.',open~c51umn or sealed reference leg.
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Provide iinivaluation.of the effect of. post, accident ambient temperatures
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on the indicated water level to. determine the change in indicated level relative to' actual' water 1evel This evaluation must include other
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sources of'arror including the effects of varying fluid' pressure and -
flashing of refe'rence ~1eg tols, team on the water level measurements.
c 3. Trovide an analysis of the iipa'ct th~a~t Die 7evel faasurement errors ~ in control and protection systems (2 above) have on the assumptions used in the plant transient and accident analysis.
This should include a review of all safety and control setpoints derived frem level signals to verify that the setpoints. will, initiate the action. required by the piant safety, analyses t!)roughout.the range of ambient.terperatures ' -,----
encountered by the ' instrumentation; includin'g accide'nt' temperatures.s-If this analysis demonstrates that level measurement errors are greater than assumed in the safety analysis, address the corrective action to be taken. _. The corrective actions considered..sho.uld, include design char;es that could be made to ensure that containment temperature effects are automatically accounted for. These measures may include setpoint changes as an acceptable corrective action for the short term. However, some fonn of temperature compensation or modification to eliminate or reduce temperature er.rors should be investigated as a long term solution.
Review and indicate th[ required revisions, as necessary, of emergency 4,
procedures to includ:. specific information obtained from the review and evaluation of Items 1, 2, and 3 to ensure that the operators are instructed on the potential for and magnitude of erroneous level sicnals. Provide 9 copy of tables, curves, or correction factors that wouTd be applied to post-f.ccident monitoring systems that will be used by plant operators.
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