ML20117C551
| ML20117C551 | |
| Person / Time | |
|---|---|
| Site: | 05000000, Susquehanna |
| Issue date: | 10/19/1983 |
| From: | Kelly G NRC |
| To: | Greenman E NRC |
| Shared Package | |
| ML20114F930 | List:
|
| References | |
| FOIA-84-616 NUDOCS 8505090457 | |
| Download: ML20117C551 (7) | |
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007 1 91983 MEMORANDUM FOR:
Edward G. Greenman, Chief, Projects Branch No. 1, Division of Project and Resident Programs THROUGH:
Ebe McCabe, Chief, Reactor Projects Section 1D(32 FROM:
Gene Kelly, Project Engineer, Reactor Projects Section ID
SUBJECT:
SUSQUEHANNA UNIT I (DN 50-387) POTENTIALLY GENERIC ISSUE MOV THERMAL OVERLOAD BYPASS CIRCUITRY ANNUNCIATOR-DESIGN
REFERENCES:
(1) PP&L Prompt LER (fax) 50-387/83-129 dated 10/7/83 (2) Reg. Guide 1.106, Rev. 1, March 1977 (3) Draft Sec. 5.e from Inspection Reports 0-387/83-21 (4) LER 50-387/83-111 dated 9/2/83 Gary Rhoads, SRI at Susquehanna, verbally described on 10/7/83 the Ref. 1 prompt LER occurrence of 9/27 which was included in Tuesday's 10/11 daily report. The problem concerns lack of reliable annunciator indication for motor-operated valve (MOV) operability at Unit I whenever bypass circuitry (required by Ref. 2) is in.effect but thermal overloads are actuated. A simplified logic schematic for typical MOV protective / control circuitry is attached.
The problems described in the Ref. 3 inspection report involve HPCI MOV HV-IF059, which supplies cooling water to the HPCI turbine's barometric condenser and the pump's lube oil cooler (simplified flow diagram is attached). This valve was subject to previous (Ref. 4 occurrence on 8/5) motor winding damage attributable to insulation degradation, and the motor was replaced. Ref. 4 also alluded to' entry into Tech. Spec. LCO 3.5.1 which allows for a 14-day HPCI out-of-service period before requiring shutdown. The more recent Ref. 1 LER does not address Tech. Spec. impact; however, it does commit to a future LER 83-140 which will presumably consider this. The information available at this time indicates that HPCI MOV-59 was rendered inoperable and remained undetected for approximately three weeks. Since this exceeds the LCO limit, a possible violation may have occurred.
Further complicating this is the fact that : (1) LCO 3.5.1 allows inoperability of HPCI for 14 days providing that Core Spray, LPCI, ADS, and RCIC are available; (2) manual control of MOV-59 was possible, and (3) FSAR Sections 6.3.2.2.1 and 7.3.1.1 indicate that certain HPCI turbine condenser equipment is not essential for HPCI operability (although the pump lube oil cooling would be).
However, while the licensee could not reasonably have been expected to find or prevent this problem, questions as to the design adequacy (bypassed / inoperable status annunciation) have been raised.
Regarding the generic inplications, Ref. 1 is clear in specifying that all other MOV's at Unit I are potentially affected. All existing DC and AC valve motors have been inspected and found satisfactory.
Interim measures have been 8505090457 841002 PDR FOIA DARFIEL84-616 PDR a
Chief, Projects Branch No. 1, DPRP 2
implemented for proper surveillance testing, and an engineering evaluation of bypass circuit (and annunciator) design is underway. A 14-day follow-up to Ref. 1 is due by end of month.
I have prepared the enclosed generic data sheet and a draft TIA addressing this issue, for your consideration. By copy of this memo to the Regional Enforcement Specialist, a determination regarding possible violation of. Tech. Specs. or Part 50 GDC is requested.
I will continue to pursue this problem with the SRI, keeping you informed.
Q-Eugene M. Kelly Project Engineer Reactor Projects Section ID
Enclosures:
1.
Generic Issue Data Sheet 2.
Draft TIA Attachments:
1.
Refs. I and 4 2.
Logic Schematic 3.
R. Starostecki T. Martin S. Ebneter H. Kister R. Keimig D. Holody G. Rhoads C. Petrone W. Bateman W. Cook
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LER Followup Review a.
LERs83-129 and 83-140,'Themal Overload Bypass Circuit Design In NRC Inspection Report 387/83-21, a problem with HPCI Valve IF059 was discussed.
Further licensee review of the issue resulted in a prompt report on October 7 with a followup report on October 21, discussing a
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problem with the control room indication of themal overload actuation.
The control circuitry is designed such that when the themal overloads are bypassed (the nomal plant conditions) the alam signifying that an overload condition exists is also bypassed.
The bypass exists on all ECCS motor operated valves to meet the requirement of Regulatory Guide 1.106 Revision 1.
This Regulatory Guide proposes three solutions to a perceived problem of using thermal overloads on intemittently operated motors.
The licensee used proposal 1.a which continuously bypasses the thermal overload protection devices and temporarily places the overloads in force only when the valve motors are undergoing periodic or maintenance testing.
The 1F059 valve was only found to be inoperable when it was attempted to be opened on September 27, 1983 and would not open.
It is postulated that the valve motor actually was damaged on September 6,1983, the last time the system was run prior to the attempt on September 27, but because of the instrumentation design the opergtors had no knowledge of the inoperability of the valve.
To assure that no other valves in the ECCS Systems were inoperable, the licensee checked the integrity of other DC Motor Operated Valve (MOV) thermal overload heater coils, and later AC MOV thermal overloads.
Procedures have also been changed to assure that the MOV test switches are left in the test position for at least30 seconds following all valve closures during testing to assure that the control roem annunciators will alarm if a themal overload condition exists.
The licensee is reviewing the design of the bypass circuitry to detemine a more acceptable design.
LER 83-140 discussed the actual reason the MOV failed.
The failure mechanism was isolated to the torque switch failing to properly operate, which resulted in the motor remaining energized long after the valve was fully shut.
This caused increased currents resulting in overloads and
_ overload heater malfunctions, and burnt motor windings, scored amatures and brushes.
The licensee disassembled the torque switch spring pack and found the following discrepancies:
Excessive grease in the spring pack.
One Belville washer was installed backwards.
The thrust washer / sleeve gap was too small.
10 A combination of these three discrepancies apparently caused the torque switch to fail to open at the proper torque.
The inspector then re-viewed the Work Authorizations previously perfonned on this valve to see if maintenance done by the licensee had caused the discrepancies noted in the torque switch spring pack.
The review found no evidence that work performed by the licensee caused the problem.
The licensee also reviewed past maintenance history and could not detennine anything improperly done by plant maintenance.
The licensee then reviewed all other Work Authoriza-tions perfonned on motor operated valves (MOV) to see if other past MOV problems may have been caused by improperly assembled spring packs.
The licensee identified 7 other MOV failures of overloads, motors, and/or torque switches which they felt may have been caused by spring pack prob-lems, and have initiated Work Authorizations to look at the spring packs on these valves.
This item will continue to be reviewed under the NRC open item 387/83-21-05.
- b. LER 83-130, Containment Isolation Valve Initiating Signals On October 7,1983, the licensee reported that a review of Technical Specifications uncovered discrepancies concerning the initiating signals for ten containment isolation valves.
Eight of the affected valves are in the Residual Heat Removal System and two are in the Reactor Water Clean-up System.
The licensee stated in LER 83-130 that a design review had been performed and verificd thtt thc currcr t at-built ccr.ditiom, zithca;!.
different from Technical Specifications, are the approved design.
The discrepancies were caused by the failure to make the proper FSAR and Technical Specification changes after the design was revised.
The licensee reported on October 21, 19E3, that further investigation had identified additional discrepancies between the FSAR tables for isolation signals and the design drawings and Technical Specifications for an additional eleven valves.
The licensee stated that two of the valves required modi-fication of the valves circuitry.
The inspector conducted an independent review of the Technical Specifications, FSAR and the design drawings in order to determine if further discrepancies existed.
In addition to the deficiencies identified by the licensee in LER 83-130, the inspector identified several other discrepancies.
The inspector met with licensee representatives on October 20 to bring all of the items to their atten-
^ tion and also later discussed the items with the NRR Technical Specifica-tion reviewer.
The licensee is currently preparing revisions for the FSAR and an amendment to the Technical Specifications in order to correct the deficiencies.
10 CFR 50.55(d) requires that at or about the time of completion of the construction of the facility, the anplicant will file any additional information needed to bring the original applicatien for license up-to-date.
Of the deficiencies identified, many concerned cases where the Final Safety Analysis Report was not updated by the licensee at the time of completion of the construction of Unit 1.
The licensee received their license on July 17, 1982.
As of October 21, 1983, the following deficiencies had not been corrected:
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Appendix A Data Shrat No.:
TI 2500/3 4/1/80 POTENTIALLY GENERIC ISSUE DATA SHEET Facility Susquehanna Unit 1 Docket No. 50-387 Date of Event 8/5 and 9/27/83 Inspection- (or other Report) 50-387/83-21 1.
Brief Description of Issue (Not required if included in supporting data)
LER's 50-387/83-111 (9/2/83) and 129 (10/7/83) describe separate instances involving the cooling water supply MOV HV-15Cr059 for HPCI Turbine barometric condenser and pump lube oil cooler.
In the first case, valve motor winding burnout was attributed to insulation breakdown.
In the second, a defective torque switch caused a locked rotor and motor burnout again. Also, a potential generic problem was identified in LER 83-129 as described in the October 12, 1983 Kelly to Greenman memo.
Probable motor damage occurring after the early September surveillance cycling of this valve rendered the HPCI system inoperable (and undetected) for approximately a three-week period between surveillances which was in excess of the 14-day Tech. Spec. LCO limit. This occurred because the valve motor's thermal overload bypass circuitry prevented the system 's out-of-service annunciation from indicating such, d
2.
How Found (If appropriate)
Preventive maintenance activity on HPCI Turbine and HPCI System surveillance testing.
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3.
Why Considered Potentially Generic (i.e. - reference applicable criteria or give reason)
Generic design of protective and control logic annunciator circuitry for MOV's.
GMK 4.
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- c. nhnade/r. Ke11v E. McCabe/E. Greenman Re.gion Originator
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Section Chief / Branch Chief 5.
Other Region Reporting that the Problem has also been identified by them Region
, Chief Reporting
, Docket No.
6.
Evaluation by IE:HQ Bulletin /
/ Circular /
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Infomation Notice /
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Other
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No further action required
/
/
SSINS N3.:
6835 IN 84-13
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UNITED STATES
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NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT
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WASHINGTON, D.C.
20555 February 28, 1984 IE INFORMATION NOTICE 84-13:
POTENTIAL DEFICIENCY IN MOTOR-OPERATED VALVE CONTROL CIRCUITS AND ANNUNCIATION Addressees:
All holders of a nuclear power reactor operating license (OL) or construction permit (CP).
Purpose:
This information notice is provided to alert licensees to a specific design in the circuitry used for control and annunciation of certain safety-related electric motor-operated valves (MOVs).
This design may, under thermal overload (TOL) bypass condition, preclude timely detection of a failure of a safety-related motor.
Affected licensees may elect to modify their design to provide con-tinuous TOL trip annunciation and indication.
No specific action or response to this notice is required.
Description of Circumstances:
On September 2, 1983, Pennsylvania Power and Light Company's (PP&L's) Susquehanna Steam Electric Station reported a condition related to a failed MOV which supplies cooling water to the barometric condenser of the high pressure coolant injection (HPCI) turbine and to the HPCI lube oil cooler pump.
The TOL had tripped when the valve torque switch malfunctioned.
This condition was not indicated or annunciated to the control room operator.
Investigation into the valve failure found a burned out electric motor.
This condition went unde-tected for approximately three weeks.
PP&L identified seve'n previous MOV failures involving overloads, electric motors, and/or valve torque switches.
The present control circuit design at Susquehanna does not annunciate a motor overload condition or a burned out motor if the key lock bypass switch is in a
" bypass" position.
The purpose of the bypass feature around the TOL device is to avoid spurious trips of MOVs under accident demand situations.
One of the positions in Regulatory Guide 1.106 is that the TOL should not preclude completion of the safety function.
At Susquehanna, the key lock bypass switch is normally kept in the bypass position.
This continuous bypass of the TOL during normal operation is one means of complying with Regulatory Guide 1.106 since a tripped TOL will not inhibit operation of the MOV.
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IN 84-13 February 28, 1984 Page 2 of 2 However, with the Susquehanna design, with the key lock in the bypass position, there is no indication of a tripped TOL.
In such designs, emphasis is placed on assuring operability of the safety function rather than on protecting individual components from damage.
However, good engineering practice would retain the TOL protection for normal or test functions of the M0V.
Such a design would permit the TOL protection for the motor to be reinstated under test conditions.
Corrective Action Taken by Licensee:
1.
Following the discovery of this situation, PP&L inspected all AC and DC motors of the MOVs and found them satisfactory.
2.
Shift supervisors were instructed that the key lock bypass switch should remain in the "open" (test) position for at least thirty (30) seconds following a valve closing operation, before the switch was placed back to the " normal" (bypass) position.
This would assure indication in the control room if the overload relay actuated to protect the motor of the MOV against a TOL condition.
3.
As an interim measure PP&L implemented a surveillance testing program, and is presently evaluating the bypass circuit design and possible changes to provide for continuous annunciation and indication of TOL trip conditions.
Other licensees may elect to provide similar capability.
If you have any questions regarding this matter, please contact the Regional Administrator of the appropriate NRC Regional Office, or this office.
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[s,JAwardL. Jordan,Iirector Division of Emergency Preparedness and Engineering Response Office of Inspection and Enforcement Technical
Contact:
W. Laudan, IE (301) 492-9759
Attachment:
List of Recently Issued IE Information Notices I
Attachment IN 84-13 February 23, 1984 LIST OF RECENTLY ISSUED IE INFORMATION NOTICES Information Date of Notice No.
Subject Issue Issued to 84-12 Failure of Soft Seat Valve 2/27/84 All power reactor Seals facilities holding an OL or CP 84-11 Training Program Deficienc-2/24/84 All power reactor ies facilities holding an OL or CP 84-10 Motor-Operated Valve Torque 2/21/84 All power reactor Switches Set Below the facilities holding manufacturer's Recommended an OL or CP Value 84-09 Lessons Learned from NRC 02/13/84 All power reactor Inspections of Fire Pro-facilities holding tection Safe Shutdown an OL or CP Systems (10 CFR 50, Appendix R) 83-63 Pontential Failures of 2/15/84 All power reactor Supp 1 Westinghouse Electric facilities holding Corporation Type SA-1 an OL Or CP 84-08 10 CFR 50.7, " Employee 2/14/84 All power reactor Protection" facilities holding an OL or CP; and NMSSS & AE 84-07 Design-Basis Threat and 02/03/84 All power reactor Review of Vehicular Access facilities holding an OL or CP; and certain fuel fabri-cation & processing facilities using or possessing a formula quantity of SNM 84-06 Steam Binding of Auxiliary 01/25/84 All power reactor Feedwater Pumps facilities holding an OL or CP 84-05 Exercise Frequency 01/16/84 All power reactor facilities holding an OL or CP 84-04 Failure of Elastomer Seated 01/18/84 All power reactor Butterfly Valves Used Only facilities holding During Cold Shutdowns an OL or CP l
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FEB 2 91984 MEMORANDUM FOR:
D. G. Eisenhut, Director, Division of Licensing, NRR J. Heltemes, Director, Office for Anaysis and Evaluation of Operational Data T. T. Martin, Director, Division of Engineering and Techni-cal Programs, Region I FROM:
R. W. Starostecki, Director, Division of Project and Resident Programs, Region I
SUBJECT:
EXTENSION OF TMI-1 SALP ASSESSMENT PERIOD In order to provide a more current assessment of license performance prior to an NRC Commission decision on the restart of TMI-1 (currently projected for June 1984), we are hereby extending the assessment period by four months, from Sep-tember 30, 1983 to January 31, 1984.
Consequently, the assessment will cover a sixteen (16) month period.
Please review the SALP input you previously provided, update the material as necessary for the four 6dditional months and submit the update to E.L. Conner of my staff by March 16,=1984.
If no update of your previous input in required, please advise Mr. Conner (FTS 488-1355) of that fact. We expect to have a SALP Board meeting on April 2,1984.
Your efforts and cooperation are appreciated.
p:!..*. :.1. CO:od By R. W. Starostecki, Director I
Division of Project and Resident Programs cc:
T. Murley, RI J. Allan, RI DPRP Branch Chiefs DETP Branch Chiefs DPRP Section Chiefs DETP Section Chiefs J. Stolz, NRR J. Van Vliet, NRR RI:DPRP RI-RP RE : PRP y
imig Stlr'bstecki
'lf 1:39 9 0FFICIAL RECORD COPY TMI2/23/84 - 0011.0.0 11/29/80 ya