ML19206A529
| ML19206A529 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 12/19/1977 |
| From: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | Herbein J METROPOLITAN EDISON CO. |
| Shared Package | |
| ML19206A530 | List: |
| References | |
| NUDOCS 7904200105 | |
| Download: ML19206A529 (2) | |
Text
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.... - *,e Cecember 19, 1977 Cocket Mc. 50-320 Metropciitan Ediscn Company ATTN: Mr. J. G. Hertein Vice President P. O. Ecx 542 Reading, PA 19603 Gentlemen:
Enclosed is IE Bulletin No. 77-07 wnich recuires action by you with regard to your pcwer reactor facility (ies) with a constructicn pernit.
Shculd you have questions regarding this Bulletin er the acticns required of you, please contact this office.
Sincerely, kf f bm- -
Scyce H. Grier Director
Enclosures:
1.
IE Eulletin 77-07 2.
List of IE Sulletins Issued in 1977 cc w/encis:
R. L. Wayne, CA Manager, Cesign 1 Construction T. Gary Brougnten, Safety & Licensing Manager G. P. Miller, Sucerintendent R. W. Heward, Jr., Project Manager
- 2. C. Arnold, Vice President, Generaticn Gerald Charnoff, Esquire Miss Mary V. Southard, Chairman Citizens for a Safe Envircnment
,,-.. a n o O(.... s 3 M1 7304200/07
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e UNITED STATES
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NUCLEAR REGULATCRY CCMMISSICN OFFICE OF INSPECTICN AND ENFCRCE iENT WASHINGTCN, D. C.
205E5 IE Sulletin No. 77-07 Date: December 19, 1977 Page 1 of 3 CONTAINMENT ELECTRICAL PENETRATION ASSE'4SLIES AT NUCLEAR FCWER PLANTS UNCER CONSTRUCT!CN Description of Circumstances.
On Octcber 3, 1977, Northeast Nuclear Energy Ccm:any re;crted to the NRC Region I Office that two central valves installed inside c:ntainment at Millstone Unit No. 2 demonstrated abncrmal operational characteristics.
The licensee re:orted that an unexpected closure of a letdcwn ficw stop valve occurred. While investigating this pecblem, the normally closed safety injection recirculation return line drain valve was fcund to be in the open ;osition. Investigation of these events revealed the cause for failure to be electrical snorts between conductors within a contain-ment lcw voltage penetration assembly.
The licensee subsequently determined that the wiring for. bath of the valves shared the same icw vcitage medule in an electrical penetrstion.
Electrical tests by the licersee revealed that 15 of the 55 conductors in the suspect connector module exhibited decreased insulation resis-tance between conductors. Based en tnis finding, it is believed that an electrical path between adjacent circuits in the c:nnector mcdule was established. This resulted in s:uricus coeraticn of the valves. Similar resistance checks performed on the retaining icw voltage modules within the affected penetration assembly revealed 17 additicnal conductors with reduced insulation resistances. All conductors with resistances less than 20 megahms were disconnected and their circuits were reconnected through spare conductors.
Examinaticn of the three remaining icw voltage penetration assem lies identified 7 additional c:nductors with resistances of less than 20 megchms. Each of these circuits were also reconnected through a scare conductor.
Investigation showed that the reduced insulation resistance was ;r:bably caused by moisture accumulation within the ;enetration assembly together with small fissures in the e:cxy seals surrcunding eacn c:nductor in the mccule. The licensee believes that meisture penetrating these cracks bI/ ~ I.S $