ML20215N401

Special Rept:On 860808,during Shutdown for Maint,Found Unidentified Wires in Environmentally Qualified Limitorque motor-operated Valves.Caused by Mfg Deficiency.Wires Replaced

ML20215N401
Person / Time
Site:	Oconee
Issue date:	10/20/1986
From:	Tucker H DUKE POWER CO.
To:	Grace J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
NUDOCS 8611050355
Download: ML20215N401 (5)

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• 4 1 Duur POWER GOMPANY P.O. BOX 33189 CHARLOT12. N.C. 28242 HALB. TUCKER - a *1 TEMNM i wwme. =v , yJ (704) 373-4831 l , p p 3\

l October 20, 1986 l

Dr. J. Nelson Grace, Regional Administrator U. S. Nuclear Regulatory Commission Region II 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323

Subject:

Oconee Nuclear Station Docket Nos. 50-269, -270, -287

Dear Dr. Grace:

By letter dated August 12, 1986, Duke Power Company (Duke) committed to provide to the NRC a Special Report documenting the findings of an investigation into the possible existence of unidentified wiring in Environmentally Qualified Limitorque Valve Operators. Accordingly, please find attached a Special Report concetning this incident.

Very truly yours,

/JBLLMs

• Hal B. Tucker PFG/35/slb Attachment xc: Mrs. Helen Pastis Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Washington, D. C. 20555 Mr. J. C. Bryant NRC Resident Inapector Oconee Nuclear Station 8611050355 861020 PDR ADOCK 05000269 S PDR h '

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L Duke Power Company Oconee Nuclear Station Special Report Possible Existence Of Unidentifed Wires l Within Environmentally Qualified Limitorque Valve Operators 4 ABSTRACT 4

Based upon results from'an inspection at other Duke Power facilities (McGuire l Nuclear Station and Catawba Nuclear Station), Oconee Unit's 1 environmentally qualified Limitorque Motor Operated Valves were inspected on Augsut 8, 1986, while the unit was shutdown for maintenance. In this inspection,' unidentified; wires were

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found in several of the valve. operators. Further inspection of Units' 2 and 3 valve operators' revealed the existence of unidentified wires in them as well. All three units have operated at 100% power while the unidentified wires were installed.

At the time of discovery, Unit I was shutdown for a Steam Generator tube leak repair. Units 2 and 3 were operating at 100% power.

The corrective action taken was to begin replacing all unidentified and questionable wires with Environmentally Qualified wire. A Justification for continued operation was submitted to the NRC by a Duke letter dated August 12, 1986.

The cause for this incident has been assessed to be a manufacturing deficiency.

1 The supplier of the valve' operators did not ensure that only environmentally

qualified wiring was utilized during the manufacturing process. A contributing.

cause is an inadequate procedure used during a Modification to replace questionable wires on Limitorque Operators in containment.

There were eight different types of wire found on the Environmentally Qualified Limitorque Operators. Seven of the wires have been qualified under various test reports to perform as necessary in the Locations in which they were found. The e eighth wire, Hypalon, was evaluated to be acceptable for the application in which it was found to be in. Thus the health and safety of the public was not endangered by this incident.

RACKGROUND The initial requirements of the Equipment Qualification (EQ) program were provided in 1967 by 10 CFR 50 Appendix A. The requirements given in 10 CFR 50. Appendix A were " Structures, systems, and components important to safety shall be designed to accommodate the effects of and to be compatible with the environmental conditions-

, associated with normal operation, maintenance, testing, and postulated accidents, including loss-of-coolant accidents". In 1978 IE Circular 78-08 was issued to

. address concerns of potential deficiencies in EQ by various Licensees. On February 8, 1979, IE Circular 78-08 was upgraded to Bulletin 79-01 due to the apparent i widespread EQ deficiencies throughout the industry.

The EQ program that we comply with now stems from Bulletin 79-01. The requirements for Environmental Qualification of electrical equipment important to safety are now provided in 10 CFR 50.49.- The EQ program must include and be based on temperature, pressure, humidity, chemical effects, radiation, aging, and other effects.

I Limitorque valve motor operators utilize internal wiring to connect various limit l and torque switches to control valve operation. All components utilized within the L operator must be environmentally qualified when used in a 10 CFR 50.49 application, i -

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' ' Specici Rsport .i Page Two j f

DESCRIPTION OF OCCURRENCE In 1964-65 Limitorque began manufacturing valve operators for Oconee. Duke specified the-functional application for each valve and Limitorque installed jumpers to conform to these specifications. At this time'there were no specific guidelines for an Equipment Qualification (EQ) program. However, the vendor, Babcock and Wilcox (B&W) issued a report showing the required manufacturing specifications for electric motor operators.

Part of the response of Duke Power for Bulletin 79-01 was to replace equipment that-did not meet the requirements of the EQ program. .A Modification was initiated to replace questionable wires on the- in-containment valve motor operators and the Reactor Building cooling units.

The Limitorque Operators have _ jumpers that go between the limit switch ' compartment i

and the torque switch compartment. These jumpers are standard on all Limitorques.

i There are also jumpers between limit switches and jumpers between torque switches

< that are installed to conform to the required functional application. These

- jumpers are also installed by Limitorque.

l When the modification was completed on Unit 3, there was no requirement to change the jumpers between the limit and torque switches. This was.because Duke was pursuing qualification of these jumpers from Limitorque. Due to this fact the limit to torque switch jumpers were not replaced on Unit 3.

, On Units 1 and 2 there was a requirement to replace these jumpers. No documentation had been received from Limitorque, so Design-felt that it .was best to replace them. The modification was implemented only on valves in containment.~

On January 14, 1986, the NRC issued Information Notice 86-03 concerning Environmental Qualification deficiencies in Limitorque Operators which had been-

. discovered at Zion in late September 1985, and subsequently at Sequoyah. Design Engineering (DE) reviewed the Information Notice for applicability to Duke Power.

, Their main concerns were for McGuire and Catawba since a modification had been

! implemented at Oconee supposedly alleviating the possibility of any deficiencies.

Realizing potential applicability, Design Engineering requested Limitorque to

. provide the control wiring manufacturer and style for operators supplied to Duke to j

j ensure traceability as required by 10 CFR 50.49.

.Limitorque responded on May 16, 1986, to the request for operator information.

Their information indicated that during the early years of manufacture, the i specific type of wiring used was not retained in their records. However, company l policy was to use type TW or TEW PVC insulated sire (TW, TEW, and TFF are all types j of PVC insulated wire). The company later switched to Raychem Flantrol wiring. In

. 1978, the~ company again switched to Rockbestos SIS.

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! Based on the Limitorque information, DE concluded that Limitorque Operators containing the PVC wire were used only outside of containment at all of the Duke nuclear units. DE evaluated the worst case outside containment harsh environment , ,

as either a pipe rupture temperature excursion to 260 degrees F or post-acc! dent recirculation radiation of 3.1E 6 Rads (Total-Integrated Dose). The PVC wire was I then evaluated by DE and determined to be qualified.for. use in the harsh ,

environment. This evaluation was concluded on July 25, 1986. At this time, DE was' satisfied that Limitorque Operators were environmentally qualified.

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On July 28, 1986, the NRC began an inspection of DE's environmental qualification data for Limitorque Operators. This inspection ended on July 31, 1986, and concluded that data was complete. The NRC then inspected several operators at McGuire Nuclear Station. During that inspection, unidentifiable wiring was found within a Limitorque Operator. Catawba was notified of this finding and began inspection of Limitorque Operators on August 5, 1986. Unidentifiable w1 ring was also found in the Catawba operators.

Oconee was notified of these findings and began inspection on August 8, 1986. The in-contninment valves on Unit 3 had unidentified wires between the limit switches and the torque switches. An unidentifiable small black wire was, also, found in several operators in containment on all three units. All environmentally qualified valves in and outside of containment were included in this inspection. All unidentifiable and type TW or TEW jumper wires are being replaced with qualified wire at the time of inspection.

CAUSE OF OCCURRENCE The cause for this incident is attributed to a manufacturing deficiency.

Limitorque Corporation did not ensure that only environmentally qualified components were supplied with the operators. The unidentifiable insulation was determined to be Hypalon from analysis by Duke Power and CHEM-BAC Laboratories, Inc.

A contributing cause to the incident is attributable to a procedure deficiency.

The implementation procedure for the modification said, " Inspect the limit switch hookup wire in each M.O.V. If the hookup wire is not from an XJ type of cable, replace it with conductors from a Duke Power cable mark number XJ type cable." The procedure should have given reference drawing numbers and a list of the specific

jumpers to be replaced.

CORRECTIVE ACTIONS l

Following the inspection performed on Unit 1, a limited inspection was made on Units 2 and 3. Based on the results of all inspections and evaluations of unidentified wires, a "Just'Ification for Continued Operation " (JCO) .for Units 2 and 3 were developed. These JCO's were submitted to the NRC along with a brief-

! report regarding this particular situation by a letter dated August 12, 1986.

On August 16, 1986 Unit I was returned to service following its maintenance outage, I at which time all Environmentally Qualified Limitorque Operators had been inspected and all unidentified and questionable wires were replaced. For Unit 2, all environmentally qualified Limitorque Operators were inspected and all unidentified L and questionable wires were replaced prior to the restart of the unit following its l . shutdown for refueling. Unit 2 was shutdown for refueling on August 16, 1986 and l was returned to service on October 14, 1986. On October 2, 1986, Unit 3 was l shutdown for maintenance due to equipment problems which brought the unit to cold l shutdown ' conditions. As a result all Environmentally Qualified Limitorque Operators for Unit 3 were inspected and all unidentified and questionable wires were replaced during the shutdown. In addition to the above, all Environmentally Qualified Limitorque Operators in the warehouse will be inspected and all unidentified and questionable wires will be replaced. Further, while Units 2 and 3 were operating, operation procedures were revised to preclude any unwanted actuations of in-containment Environmentally Qualified Limitorque

SpCcici Rep rt Page Four Operators that had not been inspected and rewired. These revisions include positioning the valve in its Engineered Safeguards (ES) position and removing power to the valve operator, or de-energizing the valve operator within 30 minutes following a containment isolation event, a time frame well before any insolution would became ineffective.

ANALYSIS OF OCCURRENCE The environmental conditions within the reactor building after an accident are of such an extreme nature.that certain specifications for wiring in vrdve operators are required. The synergistic effects of high radiation and high temperature are considered to be the most detrimental.

There were eight different. types of wire found on the Environmentally Qualified Limitorque operators at Oconee. These types were:

1. ITI hook-up wire

2. Rockbestos Firewall SIS

3. - Houston Wire and Cable XLPE

4. Vulkene (XLPE)

5. Thick insulation field run cable

6. High temperature braided wire

7. PVC (TFF & TW)

8. Hypalon The first seven types of insulation have been qualified under various test reports to perform as necessary in the locations in which they were found.

The eighth type, Hypalon, has been aged to a 40 year qualified like at 150 degrees C (302 degrees F) with no significant change in electrical properties (Reference OkoniteReportyo. 110E). EPRI Report NP-2129 indicates a recommended service limit of 5 X 10 Rads. Hypalon is susceptible to synergistic effects of elevated temperatures and radiation. Based upon the Oconee postulated environment, it is a conservative evaluation that no radiation / temperature synergistic effects would occur to render this type insulation ineffective prior to 15 hours1.736111e-4 days <br />0.00417 hours <br />2.480159e-5 weeks <br />5.7075e-6 months <br /> after a loys of coolant accident (LOCA),~ at which time the accumulated dose approaches 1 X 10 Rads. With the revision to the operator procedures to preclude unwanted.

actuations, the intended safety function of these valves (containment isolation) would not have been impaired. Therefore, the health and safety of the public were not endangered.

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