ML17054D079
| ML17054D079 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 09/12/1977 |
| From: | NRC OFFICE OF INSPECTION & ENFORCEMENT (IE) |
| To: | |
| References | |
| IEB-77-02, IEB-77-2, NUDOCS 7909050215 | |
| Download: ML17054D079 (10) | |
Text
NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON D.
C.
20555 'E Bulletin 77-02 Date: September 12, 1977 Page 1 of 2 POTENTIAL FAILURE MECHANISM IN CERTAIN WESTINGHOUSE (W) AR RELAYS WITH LATCH ATTACHMENTS Description of Circumstances:
Westinghouse recently reported that a number of AR Relays, with a latch attachment to provide a seal-in feature, have failed during the system check out of the Solid State Protection System (SSPS) at W Nuclear Instrumentation Control Division in Hunt Yalley, Maryland. Westinghouse has determined that contacts of these AR Relays can reopen after the.
re'lay coil is de-energized even though the latch mechanism is engaged.
Normal operation calls for the contacts to remain closed so that under
, abnormal conditions Safeguards
- actions, once initiated, go to completion.
The failure mechanism has been found to be caused by insufficient manu-facturing tolerances which prevent full travel af the relay contact assembly which is essential for proper relay operation.
This reduction of contact movement resulted from a design change made in the relay contact assembly in mid-1973 by the W Control Products Division, Beaver, Pennsylvania.
In addition to the tolerance problem, it was determined that excessive tightening of the contact cartridge terminal screw may also contribute tb the malfunction of the contacts during relay opera-tion where tolerances are marginal.
AR Relays using latch attachments
'nd produced prior to mid-1973 are not a matter of concern in this issue.
The enclosed W Technical Bulletin, NSD TB 77-10 was sent to all affected Westinghouse plants notifying them of the problem and of the corrective actions being taken.
The technical bulletin describes in detail the action developed by W to correct the identified problem.
The technical bulletin also provides specific wiring instructions to assure that design tolerances are not reduced by excessive tightening of electrical terminals on the relay.
V C(
IE Bulletin 77-02 Date:
September 12, 1977 Page 2 of 2 Action to Be Taken By Licensees and Permit Holders:
For all power reactor facilities with an operating license or a con-struction permit:
Describe what action you have taken to determine whether the relays of the type and vintage described in the enclosed
'I< Bulletin are in use or planned for use in safety related systems at your facility.
(2)
Describe what action you plan to take regarding replacement of any relays of the type and vintage described which are in use or planned for use in safety related systems.
Further instruction pertaining to replacement procedures can be obtained from the M Nuclear Service Department in Monroeville, Pennsylvania.
(3)
Report to this office in writing within 45 days for facilities with an operating license and withfn 60 days for facilities with a construction permit, the results of findings with regard to Item 1
ol 2.
Approval of NRC requirements for reports concerning possible generic problems has been obtained-from the U. S.
Genera'l Accounting Office.
(GAO approval B-180225 (R0072) expires 7/dl/80).
Enclosures:
1.
Extract From lh Technical Bulletin NSD-77-10 Entitled "AR Relays with Latch Attachment" 2.
List of-IE Bulletins issued in 1977
COPY identified by bo th:
The above design change was made in mid-1973 and suspect rela b
c re ays can e
2.
Manufactures code date - (located on undersid f
1 b
an be viewed only by removing the relay).
Decode as follows-: - S-rsi e o re ay base which 1,
!A=Z, I=3, T=4, C=5, H=6, G=7, E=S, A=9, R=O (Example - GGI=7/?3) round add-on Removing each contact cartridge:
The moveable contact ll b button (A square, integral moveable assembl is th ac area ws be good pre-change style).
yes e
RECOMMENDED ACTION A.
The following plants are to notify NSD if they have replaced an with latche original equipment relays with latches o
h dd d hes that have been identi fied as being made after 6/73 (HGI) and have the round, add-on contact button Sh 1 d is status, atl AR relays with latches must be identi-on.
ou any doubt fied per thy method above.
Operating plants may postpone this action until a reasonable opportunity exists (i.e. shutdown),
since testin In an this design deficiency is detectable during period f
d g.
y event, replacement parts will be made av 1 bl ic sa eguar s
soon as they are qualified.
var a
eas 1.
Solid State Protection System:
OHI 81 North Anna P~l 5, 82 D.C. Cook Pl 5 82 Joseph Far ley 81 Salem ~l
& 02 Ringhals 82 Sequoyah PT 5 <2 Beaver Valley 81 2.
Auxiliary Safeguards Cabinet:
D.C. Cook
<1 Beaver Valley 81 B.
The followin 1
g p ants will have contact cartridges available to them by the latter part of 1977 as replacements for all AR 1
~
latch attachments.
Theref a
re ays with this time
- herefore, no customer action is required at 1.
Solid State Protection System: William McGuire bl 8 82 OHI PrZ Joseph Farley >2 Watts Bar >1 5 82 Almaraz fl 5 >2 Virgil C.
Surrmer Lemoniz Nl ASCO Prl Byron
"'1 5 42 Braidwood Il E 82 Ringhal s 3
8 84 Beaver Valley k2 Marble Hill-<1 5, 82 Millstone 8
'RSKO Catawba Pl 8 82 Commanche Peak
<1 Enclosure 1
Page 2 of 3
COPY V
- 2. Auxiliary Safeguards Cabinet: William NcGuire 81
& 82 OHI kl
& n"2 Joseph Farley hl
& 82 Almaraz 81 8 82 Yirgil C.
Summer Lemoniz 81
& 82 Byron ~l
& k2 Braidwood 81
& P2 Beaver Yalley 82 Angra 01
- 0. C. Cook 42 l'lorth Anna
<1
& 82 C.
On all future applications of AR relays with latch attachments, use only the approved contact cartridge that will result from the resolution of this problem.
Once qualified, it will have a unique identification code.
D.
Upon installation of any contact cartridge, new or existing, or the changing of any wire terminations to any AR relay, the maximum torque applied to the terminal screws shall not exceed 10 inch-pounds.
COPY Encl osur e 1
Page 3 of 3 1 IV I
al
IE Bulletin 77-02 LISTING OF IE BULLETINS ISSUED IN 1977 Bulletin No.
Subject First Date Issued Issued To 70-01 Pneumatic Time 4-29-77 Delay Set Point Drift All Holders of Operating License (OL} or Construc-tion Permit (CP)
Enclosure 2
Page 1 of 1
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