ML19260C221
| ML19260C221 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 11/06/1979 |
| From: | Lainas G Office of Nuclear Reactor Regulation |
| To: | Reid R Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 7912260082 | |
| Download: ML19260C221 (1) | |
Text
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NUCLEAR REGULATORY COMMISSION E
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NOV 6 1979 MEMORANDUM FOR:
R. Reid, Chief Operating Reactors Branch #4 Division of Operating Reactors FROM:
G. Lainas, Chief Plant Systems Branch Division of Operating Reactors
SUBJECT:
DAVIS-BESSE 1 - RELAY SOCKET CONTACT FAILURES (TAC 12016)
In accordance with your request per TAC 12016, we have reviewed the relay failures at the Davis-Besse Nuclear Power Plant (LER #79-077/
031-0) in which pins on control relays were not making proper contact with their sockets. Similar failures have been previously reported; via LERs, at other nuclear power facilities (Monticello and Duane Arnold). Since this evidenced a potentially generic problem with regard to the reliability of these plug-in type relays, we drafted a proposed IE Bulletin (enclosed) which has been sent to the Office of I&E for their consideration. We will keep you informed of actions taken en this matter.
Please advise me if this satisfies your concerns.
D T
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/G.Laina Chief
/
Plant Systems Branch Division of Operating Reactors
Enclosure:
As stated
Contact:
R. Ker all, X28215 cc w enclosure:
D. 'isenhut I6i6 073 G. Lainas F. Rosa
'. Thomas G. Vissing D. Tondi R. Kendall O
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OCT 2 41979 MEMORANDUM FOR:
E. Jordan, Assistant Director Division of Reactor Operations Inspection Office of Inspection and Enforcement FROM:
Darrell G. Eisenhut, Acting Director Division of Operating Reactors Office of Nuclear Reactor Regulation
SUBJECT:
RELAY SOCKET CONTACT FAILURES
REFERENCE:
1.
Memorandum from Eisenhut to Jordan "LER on Monticello AGASTAT Relay Socket Contact Failure (LER #78-029/0lT-0)"
By letter dated February 13, 1979, Reference 1, we informed you of the failure of an AGASTAT *CR0095 relay socket at the Monticello Nuclear Power Plant.
In this event, one of the socket contacts became disengaged from the socket resulting in the failure of an ATWS-RPT high pressure instrument channel from the Protection System.
Simil ar failures in non-safety related circuits were also experienced at the Monticello Plant. At that time, we recorrnended an information notice to the licensee.
On July 5,1979, Davis-Besse Nuclear Power Station, Unit 1, reported similar failures, (LER *79-077/031-0), in which pins on control relays were not making proper contact with their sockets.
These failures prevented the proper operation of a Safety System Auxiliary Feedwater Pump Turbine Steam Inlet Valve (MS106).
The subject relays are Deutsch 4AX1603 and #99699-7825W, and the socket base used to accommodate these relays is a Deutsch =29-401091 The problem was corrected by bending the relay pins slightly outwarJ so that good contact was made between the relay pins and the socket base.
This second occurrence of this type of failure (bad connections between relay pins and relay socket contacts) evidences a pctentially generic problem with regard to the reliability of plug-in type relays used in safety systems. Specifically, the capability of these types of connections to withstand seismic and vibrational forces is questioned.
As such, the Plant Systems Branch suggests the issuance of the proposed IE Bulletin (enclosed) to all licensees requesting ir. formation regarding the number of failures of plug-in type relays experienced, the associated model numbers of relays and sockets involved, and the seismic qualifi-cation of these components in Class lE systems.
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ENCLOSURE s
E. Jordan OCT 2 41979 Please keep us informed of actions taken on this matter.
~}3 v'. - f i c..u / g.
o Darrell G. Eisenhut, Acting Director Division of Operating Reactors Office of Nuclear Reactor Regulation
Enclosure:
Proposed IE Bulletin
Contact:
R. Kendall, X28218 cc w/ enclosure:
D. Eisenhut B. Grimes R. Satterfield F. Rosa G. Lainas V. Thomas D. Tondi R. Scholl P. Shenanski
[ R. Kendall 1414 n f g-PSB Section A iUiV Ur>
ENCLOSURE 3
PROPOSED IE BULLETIN RELAY SOCKET CONTACT FAILURES Description of Circumstances:
TP is Bulletin was prompted by reports from licensees, i.e., LERs, on incidents where plug-in type relays failed to energize, thus disabling the associated circuits and components. Specifically, bad connections between relay pins and their base contacts and socket contact failures have been experienced.
These failures evidence a potentially generic problem with regard to the reliability of plug-in type relays in safety related systems.
Actions to be Taken by Licensees:
For all power reactor facilities with a construction permit or an operating license:
1.
Describe, by model number, all mechanical plug-in type relays and sockets used in Class lE circuits at your facility.
2.
State whether and describe how the relay and relay socket combina-tions identified in 1 above were seismically qualified. Where qualification was not done by testing, provide the technical basis and analysis employed for the qualification determination.
For facilities with an operating license only:
3.
List all failures of clug-in type relays experienced at your facil ity.
Include the manufacturer, the model numbers of the subject relays and sockets, whether or not the relay was mechani-cally restrained, and the associated circuits and/or compone. :s which were rendered inoperable due to these failures.
List those failures of safety related systems separate fron those in non-safety related systems.
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