ML20002C462
| ML20002C462 | |
| Person / Time | |
|---|---|
| Site: | Big Rock Point File:Consumers Energy icon.png |
| Issue date: | 05/22/1975 |
| From: | Sewell R CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8101100333 | |
| Download: ML20002C462 (4) | |
Text
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. N Division of Reactor Licensing chet 50-155 D
US Nuclear Regulatory Commission co License DPR-6 Washington, DC 20555 Big Rock Point Plant Gentlemen:
Several questions have been transmitted to Consumers Power Company verbally regarding our May 15, 1975 letter to the Nuclear Regulatory Commission. The purpose of this letter is to formally document the verbal responses to these questions.
The first question regarded the statement at the bottom of the first page of the May 15 letter. Specifical3y, information was requested regarding the areas in which a technical audit would be per-formed. These areas were:
1.
Verification of completeness of the Tank Fo.ce in meeting their charter (refer to Response No 1, first Items 1 and 2).
2.
Check on the process used by the Task Force to decide which specific components should be investigated.
3 Review the following analyses:
a.
SUNTAC analysis for containment pressure - temperature envelope.
b.
Analysis of radiation doses.
c.
Analysis of containment water level.
h.
Review engineering analysis for equipment that is described in Special Report 21 by " Qualified by Engineering Analyses."
The technical audits in these areas will be completed prior to returning the plant to service. Any discrepancies identified having safety significance vill be corrected prior to returning the plant to service.
t 81011003 M 5745
. Division of R:tetor Lictnsing 2
Docket 50-155, License DPR-6 Big Rock Point Plant May 22, 1975 The motor operator environmental testing was described on Page 18 of the attachment to the May 15, 1975 letter. There was a question whether the motor operators that were actually tested were identical to the motor operators that were listed as being represented.
With one exception, these motor operators were identical to the motor operators tested, this exception being MO-7050, the motor operator for the main steam isolation valve. This motor operator was larger than the motor operator tested but similar in design features with identical materials used in the critical components; ie, motor, seals and switches.
It was concluded that the testing performed was adequate because of the similarity of design features and because MO-7050 is required to operate within the first two minutes of the postulated accident.
Table I of Response No 2 states in places under the column titled Humidity, " Assume 100."
This assumption was applied for specifi-cation purposes to all components evaluated that were located within containment.
This assumption is considered conservative and was used in lieu of specifically calculating the actual humidity conditions. All equipment evaluated within the containment was evaluated to 100 percent relative hunidity.
On Page 32, the response regarding solenoid valve evaluation (humidity) states in part, "...high humidity or submerging them in water could cause the solenoid coil to short out..." The intent of this statement was to convey that the high humidity or the submergence con-dition might not cause these solenoids to short out.
If this were the case, the solenoid would operate normally. If the solenoid coil shorted out, the solenoids would fail such that the valves they operated would fail in the safe direction. No specific consideration was given possible " hot short" failures under the containment environmental con-ditions because of the satisfactory cable testing as described else-where in the attachment to the May 15 letter and because of the lack of congestion of other electrical equipment in these areas where these solenoids are located.
Item F on Page 32 describes the evaluation performed on June-tion boxes. The Regulatory Staff has requested amplification of this evaluation. These junction boxes are covered type boxes and the cover is sealed with a rubber gasket. Pressure is not expected to build up in these junction boxes in that the openings for conduit are not sealed.
Therefore, there is no concern for collapse of these boxes during a pressure transient. Some of the connections in these junction boxes are mechanical terminations (" States" terminal blocks) that are not in-sulated.
These terminations are well separated with areas between the terminations to prevent short-circuiting. In addition, the boxes i
themselves provide an adequate spray-tight enclosure.
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8 Division of Re:ctor Licensing 3
-Docket 50-155, License DPR-6 Big Rock Point Plant Nhy 22, 1975 On Page 30,.the evaluation of the concsinment level switches was described. Some confusion existed with respect to the pressure evaluation. This description of the evaluation meant to convey that the existing level switches were compared to a similar newer model switch which has been environmentally qualified. This comparison'showed.
that the pressure switch housing had been thickened. However, the re-mainder of the pres 3ure switch was identical. Based on this comparison, it was concluded that the level switch would perform satisfactorily under the postulated environmental conditions. This level switch hous-ing is not exposed to a differential pressure during the postulated accident. Further, it is noted that the working pressure of the level s
-switch housing exc seds the pressures analyzed for the break spectrum, although it is slightly less than the containment presse e envelope used in other specifications, On Page 30, regarding PS-706hA and PS-7064B, clarification was requested as to the basis of the statement that these pressure switches will not be adversely affected by radiation. This statement was based on past experience and knowledge of the performance of the materials used in the construction of these pressure switches. This knowledge and the fact that these pressure switches are required only in the early minutes of a postulated LOCA lead to the conclusion that these pressure switches "will not be adversely affected by radiation."
k Yours very truly, 0
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JJC RBS/ds Ralph B. Sewell Nuclear Licensing Administrator l
CC: JGKeppler, USNRC l
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CONTROL NO:- 5 9 45 FILE:-
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50-155 DESCRIPTION:
ENCLOSURES:
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Ltr re our request concerning their 5-L5-75 ler..... resp'onding' to questions. concerning technical audits.....
DONO REAIOV$
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