ML19206A559
| ML19206A559 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 12/19/1977 |
| From: | Herbein J Metropolitan Edison Co |
| To: | Grier B NRC Office of Inspection & Enforcement (IE Region I) |
| References | |
| GQL-1750, NUDOCS 7904200139 | |
| Download: ML19206A559 (1) | |
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PCST CFFICE BOX 542 REAclNG, PENNSYLVANIA 19603 TELEFHONE 215 - 329 4601 December 1;, 1977 GQL 1750
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Office of Inspecticn & Inforcenent 2.e.,a, n -r 631 Park Avenue idng of Prussia, Pennsylvania 19106 tear Sir:
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In response to ycur letter dated :Tovenber h,1977, and the action requested in II Eulletin 77-Ok cencerning the design perfer ance cf a systen for cen-trolling pH cf centainment sun; vater following a 1CCA, we wish to advise c.w.
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- 2 eat Re-eval Systen (3uilding Spray ;crtien) utilices a d
3 crated '4ater and Sodiu: Hyd cxide Solutien for heat and iodine rencvs.1 as described in Chapter o cf the ?SAR. Frcser :H centrci is inherent in the design cf the syste= and requires ne separate system for pH centrcl
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has concluded in Sur.-lenent 1 of the ~'C-2 Safe
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6.0, paragraph 6.2.3, page 6-1) that it Osa neet the design criteria with a sin 21e active failure er.d is therefore accen. table.
Very truly yours,
_., c.. G. rerten J. G. Herbein Vice ? resident cc: Dr. "rnst 7c1genau, Director Office of ~.nspection a.nd Enforcement U. S..!uclear Regulate:/ Cc=icsicn Washington, J. c.
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.s"J December 19, 1977 Docket No. 50-320 Metropolitan Ediscn Ccmpany ATTN: Mr. J. G. Herbein Vice President P. O. Box 542 Reading, PA 19603 Gentlemen:
Enclosed is IE Sulletin No. 77-07 which requires action by you with regard to your pcwer reactor facility (ies) with a construction permit.
Should you have questions regarding this Bulletin er the actions required of you, please contact this office.
Sincerely, 4W
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[,Boyce H. Grier U'
Director
Enclosures:
1.
IE Sulletin 77-07 2.
List of IE Bulletins Issued in 1977 cc w/encis:
R. L. Wayne, QA Manager, Design & Ccnstruction T. Gary Brcughton, Safety & Licensing Manager G. P. Miller, Superintendent R. W. Heward, Jr., Project Manager R. C. Arnold, Vice President, Generation Gerald Charnoff, Esquire Miss Mary V. Southard, Chairman Citizens for a Safe Environment 7904200los c.-.
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UNITED STATES NUCLEAR REGULATORY CCMMISSION OFFICE OF INSPECTICN AND ENFORCEMENT WASHINGTON, D. C.
20555 IE Bulletin No. 77-07 Date: December 19, 1977 Page 1 of 3 CCNTAINMENT ELECTRICAL PENETRATICN ASSEMBLIES AT NUCLEAR POWER PLANTS UNDER CONSTRUCTICN Description of Circunstances:
On October 3,1977, Northeast Nuclear Energy Com::any reported to the NRC Region I Office that two control valves installed inside containment at Millstone Unit No. 2 demonstrated abnormal operational characteristics.
The licensee reported that an unexpected closure of a letdown flow stoo valve occurred. While investigating this problem, the normally closed safety injection recirculation return line drain valve was found to be in the open position.
Investigation of these events revealed the cause for failure to be electrical shorts between conductors within a contain-ment low voltage penetration assembly.
The 1icensee subsequently datermined that the wiring for both of the valves shared the same low voltage module in an electrical penetration.
Electrical tests by the licensee revealed that 15 of the 85 conductors in the suspect connector module exhibited decreased insulation resis-tance between conductors. Based on this finding, it is believed that an electrical path between adjacent circuits in the connector module was established. This resulted in spurious operation of the valves. Similar resistance checks performed on the remaining low voltage modules within the affected penetration assembly revealcd 17 additional conductors with reduced insulation resistances. All conductors with resistances less than 20 megohms were disconnected and their circuits were reconnected through spare conductors.
Examination of the three remaining low voltage penetration assemblies identified 7 additional conductors with resistances of less than 20 m gohms.
Each of these circuits were also reconnected through a spare canductor.
Investigation showed that the reduced insulation resistance was probably caused by moisture accumulation within the penetration assembly together with small fissures in the e:: oxy seals surrounding each conductor in the module. The licensee believes that moisture penetrating these cracks
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