GO2-83-110, Final Deficiency Rept,Condition 296 Re Loose Internal Assembly Screws on GE Type Hfa Relays.Caused by Design or QC Deficiency by Relay Manufacturer.Also Reportable Under Part 21

Final Deficiency Rept,Condition 296 Re Loose Internal Assembly Screws on GE Type Hfa Relays.Caused by Design or QC Deficiency by Relay Manufacturer.Also Reportable Under Part 21

ML20083B691
Person / Time
Site:	Columbia
Issue date:	11/29/1983
From:	Sorensen G, Sorensen G WASHINGTON PUBLIC POWER SUPPLY SYSTEM
To:	Martin J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
References
REF-PT21-83 10CFR-050.55E, 10CFR-50.55E, 296, G2-83-1101, GO2-83-1101, NUDOCS 8312210250
Download: ML20083B691 (3)

Text

_ _ _ _ _ ____-__ _

i RECGVB)

!!r.C Washington Public Power Supply System P.O. Box 968 3000 GeorgeWashingtonWay Richland, Washington 99352 l'13 DEC -7 li A l').L509 3f2 5000 November 29, 1983 G02-83-1101 REC:GW,'r Mr. J. B. Martin Regional Administrator j i U.S. Nuclear Regulatory Commission l Region V l 1450 Maria Lane, Suite 210 Walnut Creek, California 94596 i

l

Subject:

NUCLEAR PROJECT N0. 2 10CFR50.55(e) CONDITION #296 LOOSE INTERNAL ASSEMBLY SCREWS ON HFA RELAYS

Reference:

Telecon dated November 17, 1983, R.T. Johnson to Tolbert Young, same subject.

In accordance with the provisions of 10CFR50.55(e), your office was informed by the reference of the subject condition. The attachment provides the Project's final report on Condition #296.

If there are any questions concerning this matter, please contact Roger Johnson, WNP-2 Project QA Manager, at 377-2501, extension 2712.

% bk j G. C. Sorensen l Manager, Regulatory Programs JGT/kd

Attachment:

As stated cc: W.S. Chin, BPA N.D. Lewis, EFSEC A. Toth, NRC Resident Inspector Document' Control Desk, NRC 8312210250 831129 PDR ADOCK 05000397 S PDR Y Th7

J',

WASHINGTON PUBLIC POWER SUPPLY SYSTEM NUCLEAR PROJECT NO. 2 DOCKET N0. 50-397 LICENSE N0. CPPR-93 10CFR50.55(e) CONDITION #296 LOOSE INTERNAL ASSEMBLY SCREWS ON HFA RELAYS FINAL REPOP,T Description of Deficiency All the GE Co. Type HFA auxiliary relays used in safety-related systems at WNP-2 were replaced with new Class 1E qualified " Century" series HFA relays because of the HFA coil bobbin failures reported in GE Service Advice Numbers 721-PSM-152.1, 152.2, and 152.2A. When the relays were energized following replacement, test personnel noticed that some of these relays exhibited excessive hum and vibration.

Further inspection of these relays revealed that the two inner assembly screws which connect the mounting plate to the magnetic core and coil assembly were loose. Of a group of 58 HFA's inspected, approximately 60% were found with these assembly screws not torqued to the recommended 19-21 inch-pounds. Some of the relays had screws loose enough so that the normally-open contact wipe was lost.

Safety Implication '

On the HFA relay, the magnetic core pole face acts as a stop for the armature stop screw and is the reference point for the normally-open contact wipe adjust-ments. Even a small amount of looseness can result in less than minimum normally-open contact wipe as specified in the relay setting instructions. Since the seismic qualification was performed with properly adjusted contacts, a relay with less than minimum contact wipe does not fall within the component qualification limits. Further loosening could result in loss of contact for the normally-open contacts, and eventually to total loss of relay function if the core and coil assembly came loose from the mounting plate. Such failures of the HFA relays could cause a large variety of safety system failures in various safety systems in which they are used at WNP-2.

There are a total of 261 of the HFA relays used in the safety systems at WNP-2.

These safety systems are as follows:

ADS - Automatic Depressurization Syste' RHR - Residual Heat Removal System LPCS - Low Pressure Core Spray System RCIC - Reactore Core Isolation Cooling System HPCS - High Pressure Core Spray System RPS - Reactor Protection System The condition is considered to be a reportable deficiency under 10CFR50.55(e) and Part 21 criteria.

Cause of Deficiency The screws which were found loose were the two inner assembly screws which connect the mounting plate to the magnetic core and coil assembly. This entire assembly is fastened to the relay case with four screws which are accessible.

j.

10CFRCO.55(e) Condition #296 LOOSE INTERNAL ASSEMBLY SCREWS ON HFA RELAYS Page 2 GE Co. Service Advice 721-PSM-152.1 recommends checking the four external screws for tightness during routine relay maintenance inspections but does not address the two inner assembly screws. The inner assembly screws are not accessible without disassembling the relay and hence would not normally be checked for tight-ness when installing the relay or during routine relay maintenance. Hence, we conclude that these screws were intended by the relay manufacturer not to require retightening for the life of the relay if properly assembled at the factory. There-(

fore, the cause of this deficiency is either a design deficiency or a quality control deficiency by the relay manufacturer.

Corrective Action l All " Century" series Type HFA relays procured on Purchase Order No. 52637 will be

( disassembled, plate to core assembly screws properly torqued, reassembled, and contact and pickup calibration checked in accordance with Procedure SLT-S108.0-3 and FDI No. TCJN. This deficiency will be referred to the relay manufacturer for I his evaluation as a potential 10CFR50 Part 21 reportable defect and to confirm his recommendations on torque values and periodic checks on the subject core to mounting plate inner assembly screws. The work will be completed to meet safety system operating requirements for fuel load.

Actions to Prevent Recurrence There are no generic considerations for this deficiency at WNP-2 because all HFA relays used in safety systems at WNP-2 are covered by this report. Any possible generic effects to other nuclear plants using HFA relays will be evaluated by the relay vendor.

_ _ _ _ - _ - _ _ _ _ _ - _ _ _ _ _ _ _ _ -