ML19329E450
| ML19329E450 | |
| Person / Time | |
|---|---|
| Site: | Midland |
| Issue date: | 12/19/1977 |
| From: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Howell S CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| References | |
| NUDOCS 8006160254 | |
| Download: ML19329E450 (1) | |
Text
\\
1 m
e l
n CEC 191977 Docket No. 50-329 Docket No. 50-330 1
TlHS DOCUMENT CONTAINS Consueers Pover Coepany P00p quggy PAGES ATTN:
Mr. Stephen R. Howell Vice President 1945 k*est Parnall Road 1
Jackson, h1 46201 j
i Centlement I
i Enclosed is IE Bulletin Iro. 77-07 which requires action by you with regard to your power resetor facility with a construction permit.
I Should you have questions regarding this Bulletin or the actions required of you, please contact this office.
I i
Sincerely,
)
l 1
r James G. Keppler Director l
Enclosures:
i
- 1. IE Sulletin No. 77-07 l
- 2. List of It tviletins Issued in 1977 cc w/ecci:
Central Files l
Reproduction Unit NRC 20b l
-i Ronald Callen, Michigsn Public Service Coimission l
Dr. 'Jayne E. North Myron H. Cherry, Chicago 81so 26 L/
/D E&P 8
0 I
RIII g { RII{
j orr.c
- fd7ishman/1s Kh,}er uw
.. in. - e. ;
j.
12/19/77 NRC roam 333 (9 76) NRCM 0240 W us e. sovsanwsme rninvins orricas eers -ene-eae
y
<~
IE Bulletic No. 77-07
.DecerSer L9., 19 77 CONTAIhMENT ELECTRICAL PENETP.ATION ASSEM3 LIES AT NUCLE.Ut ?0VER PLANTS UNDER CONSTRUCTION Description of Circumstancas:
On October 3,1977, Northeasc M".; ear Energy Conpany reported to the NRC Region 1 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 letdewn flow stop valve occurred. '4hile investigating this problem, the normally closed safety injection recirculation return lina drain valve was found to be in the open position. IcVestigation of thase events revealed the cause for failure to be electrical shorts betueen conductors within a contain-manc Icv voltage penetration assembly.
ThS licensee subsequently determined that the wiring for both of the valves shared the sa e Icv voltage module in an electrical penetration.
Electrical tests by the licensee revealed that 15 of the 85 conductors in the suspect connector cedule exhibited decreased insulation resis-tance bet.een conduct' ors. Eased on this finding, it is believed that an electrical path between adjacent circuits in the connector module was es tablished. This resulted in spurious operation of the valves. Similar resistance checka perforced on the remaining Icv voltage modules within the affected penetration assembly revealed 17 additional conductors with reduced insulation resistances. All conductors with resistances less
)
than 20 megoh=s were disconnected and their circuits were reconnected through spara conductors.
Examination of the three remaining Icw voltage penetration asse=blies identified 7 additional conductors with resistances of less than 20 megohes. Each of these circuits were also reconnected through a spare conductor.
Investigation showed that the reduced insulation resistance was probably caused by moisture accuculation within the penetration assenbly together with scall fissures in the epcxy seals surrounding each conductor in the module. The licensee believes that moisture penetrating these cracks qqgiZ 00IOh
t IE Bulletie No. 77-07 Dececher 19, 1977 reduced the insulation resistance between adjacent conductors. To prevent further degradation from noisture buildup within the penetration assenblies, the licensee re-established a dry nitrogen pressure of 24 PSIG in the, penetrations.
Subsequently phe liceesee reported that a second event of a similar nature occurred on October 14, 1977. In this instance the sample iso-latidn valve for the pressurizer surge line failed to close on coe=ted.
Investigation into this event indicated that electrical shorts heeveen conductors due to a moisture accumulation problem were the probable cause,for valve misoperation. The shorted wires were disconnected and the valve was de-energized in the closed position.
In discussions on the issue with the licensee and the electrical penetration vendor, General Electric Company, NRC staff determined that maintenance of nitrogen pressure is essential to the integrity of both high and Iov voltage penetration assemblies. The Ceneral Electric Company sperf fies in its panetration assembly maintenance and operation manual that a 15 PSIG dry nitrogen pressure should be maintained on lov voltage units while 30 PSIG should be maintained on high voltage units.
Action To Be Taken By Applicants of all Fever Reactor Facilities With a Construction Fermit:
Containment Electrical 7enetrations - Tor safety related systems 1.0 Do you have containment electrical penetrations that are of the G. E. Series 100, or are otherwise similar in that they depend upon an epcxy sealant and a dry nitrogen pressure environ =ent to ensure that the electrical and prassure characteristics are maintained so as to ensure the functional capability as required by the plant's safety analysis report; namely, (1) to ensure adequate functioning of electrical safety-related equipment and (2) to ensure containment leak ti htness? If you do use pene-trations of this type at your facility describe the manufacturer and model number of these units.
1.1 If you do not have penetratio.n assemblies of the type (s) referenced in Item 1.0 above, describe the type (s) of penetrations e.g.,
manufacturer and nodel nu=her new in use or planned for use in safety systems at your facility.
e A
~ -
S IE Sulletin No. 77-07 Dece bar 19, 1977 1.2 Do the transition connector pins ichedded in the epcxy as discussed in Item 1.0 above, have an insulation jacket?
2.0 For these penetrations referenced in Item 1 above, has the manufacturer's prescribed nitrogen pressure been maintained at all ti=es during shipping, storage and installation?
3.0 Is there a need, as determined by either the vendor or yourself, to maintain penetrations pressurized during norcal operation, to assure functionability during a LOCA.
3.1 What ceasures have you taken to ensure that penetrations of this type vill perform their design function under 1,0CA conditions?
(design reviews, analyses or tests)?
3.2 Are the seasures that provide this assurance adequate to safisfy the Com=ission's regulations (GDC 4. Appeedix A to Part 50; QA Criteria, Appendix B to Part 50)7 4.0 Provida your response to Ite=s 1.0 through 3.2 abeve in writing within 30 days.
Responses should be submitted to the Director of the appropriate NRC Regional Office. A copy of your response should be forwarded to the U. S. Nuclear Regulatory Cot =ission.
Office of Inspection and Enforcement, Division of Reactor Construction Inspection, Washington, D. C.
20555.
Approved by GAO, 3180225 (R0072); clearance expires 7-31-80.
Approval was given under a blanket clearance specifically for identified generic problems.
4 m
O
i IE Bulletin No. 77-07 December 19, 1977 LISTING OF IE BULLETINS ISSUED IN 1977 Bulletin Subject Date Issued Issued To No.
77-06 Potential Problems with 11/22/77 All Power Containment Electrical Reactor Facilities Penetration Assemblies with an Operating License (OL)77-05A Supplement 77-05A to 11/14/77 All Power IE Bulletin No. 77 Reactor Facilities Electrical Connector with an Operating Assemblies License (OL) or Construction Permit (CP) 77-05 Electrical Connector 11/8/77 All Power Assemblies Reactor Facilities with an Operating License (OL) or Construction Permit (CP) 77-04 Calculational Error 11/4/77 All PWR Power Affecting the Design Reactor Facilities Performance of a System with an Operating for Controlling pH of License (CL) or Contain=ent Sump Water Construction Follcwing a LOCA Permit (CF) 77-03 On-Line Testing of 9/12/77 All W Power the W Solid State Reactor' Tacilities Protection System with an Operating License (OL) or Construction Permic (CP) s 77-02 Potential Failure 9/12/77 All Holders of Mechanism in Certain Operating Licenses W AR Relays with (OL) or Construction Latch Attach =ents Permits (CP) 1 of 2 90
3 e
IE Bulletin No. 77-07 December 19, 1977 LISTING OF IE BULLETINS ISSUED IN 1977 Bulletin Subject Date Issued Issued To No.
77-01 Pneumatic Time 4/29/77 All Holders of Delay Relay Set Operating Licenses Point Drift (OL) or Construction Permits (CP)
I 1
2 of 2 o