ML20138R205

Safety Evaluation Conditionally Accepting Util Response to Generic Ltr 83-28,Items 4.2.1 & 4.2.2 Re Periodic Maint Program & Parameter Trending,Respectively

ML20138R205
Person / Time
Site:	Arkansas Nuclear
Issue date:	12/17/1985
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20138R176	List: ML20138R175 ML20138R205
References
GL-83-28, NUDOCS 8512310044
Download: ML20138R205 (3)

Text

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UNITED STATES g )

, NUCLEAR REGULATORY COMMISSION '

r,. j WASHINGTON, D. C. 20555

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SAFETY E'/ALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION CONCERMING THE REACTOR TRI'P SYSTEM RELIABILITY ITEMS 4.2.1 AND 4'.2.2 0F GENERIC LETTER 83-28 -

FOR f.

ARXANSAS NUCLEAR ONE, UNITS 'l & 2 ARKANSAS F0'IER AND LIGHT COMPj" jY,'

DOCKET NOS. 50-313 & 50-368

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INTRODUCTION On July 8,1983, th'e Nuclear Regulatory Commission (NRC) issued Generic Letter (GL) 83-28. This letter addressed intermediate-term actions to be taken by licensees and applicants aimed at assuring that a comprehensive i

. program of preventive maintenance and surveillance testing is implemented for the reactor trip breakers (RTBs) in pressurized water reactors. In u

L particular, Item 4.2 of the letter required the licensees and applicants to submit a description of their preventive maintenance and surveillarce program

' to ensure reliable reactor trip breaker operation. The description of the I

submitted program was to include the following:

I GL, Item 4.2.1 A planned program of periodic maintenance, including

' lubrication, housekeeping, and other items recommended by the equipment supplier.

1 GL, Item 4.2.2 Trending of parameters affecting operation and measured during testing to forecast degradation of operation.

l Arkansas Power and Light Company, the licensee- for Arkansas Nuclear One, Units'

' I and 2, subnitted responses to the Generic Letter on July 8,1983,'and April 23, 1985. This report presents an evaluation of the adequacy of those 5

responses and of the licensee's preventive maintenance and surveillance programs for RTBs.

f 2. EVALUATION CRITERIA 2.1 Periodic Maintenance Program '

j The primary criteria for an acceptable periodic maintenarce program are.

contained in Maintenance Instruction GEI-50299EI*, Power Circuit Breakers, Types AK-2/2A-15, AK-2/3/2A/3A-25, AKU-2/3/2A/3A-25," ar.d Service Advice 175-9.35 and 175-9.20, by General Electric, and NRC IE Information Notice No. 85-58. We have reviewed these items and endorsed the maintenance program 8512310044.851217 PDR ADOCK 05000313 "

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i they describe. The criteria include those items in the General Electric instructions and advisories that relate to the safety function of the breaker, supplemented by those measurements which must be taken to accumulate data for trending. Those items identified for maintenance at six month j intervals that should be included in the licensee's RTB maintenance program 4

are:

i 1. Verification of breaker cleanliness and insulation structure; all j foreign materials, such as paint, dust, or oil, should be removed to j prevent electrical breakdown between points of different potential; l1 l

2. Verification of breaker physical condition, including wiring insulation and termination, all retaining rings, pole bases, are quencher, stationary and movable contacts, and tightness of nuts and bolts;

3. - Verification of proper manual operation of the creaker, including checks for excessive friction, trip bar freedom, latch engagement, operating i; mechanism alignment and freedem, and undervoltage trip (UVT) device h armature freedom; 1

4 Verification of the optimum freedom of the armature;

5. Verification of proper trip latch engagement as specified in-Service Advice 175-9.35, Item #S2. ,

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6. Verification of undervoltage pick-up setting, as specified in Service Advice 175-9.3S, Item #S3, and dropout voltage; j

7 Verification that.the trip torque required on the trip shaft is less j

a than 1.5 pound-inches, as specified in Service Advice 175-9.3S, Item #S4; "Before" and "After" maintenance torque values should be recorded;

8. Verification of positive tripping by checking the adjustment between the UVT device'and trip paddle as specified in Service Advice 175-9.35, Item

1. S5; i 9. Verification of proper trip response. time as specified in Service Advice

-175-9.3S, Item #S6; t 10. Shunt Trip Attachment (STA) operation verification;

11. Examination and cleaning of breaker enclosure;

12. Functional test of the breaker prior to returning it to service. ,

2.2 Trending of Parameters Generic Letter Item 4.2.2 specifies that the licensee's preventative maintenance and surveillance program is to include trending of parameters affecting operation and measured during testing to forecast degradation of -

operation. The parameters measured during the maintenance program described a .

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above which are applicable for trending are undervoltage trip attachment dropout voltage, trip torque, and breaker response time for undervoltage trip. The staff position is that the above three parameters in addition to the breaker insulation resistance are acceptable and recommended trending l

parameters to forecast breaker operation degradation or failure. If subsequent experience indicates that any of these parameters is not useful as

, a tool to anticipate failure.s or degradation, the licensee may, with justification and NRC approval, elect to remove that parameter from those to

! be tracked.

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{ 3. EVALUATION

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. 3.1 Evaluation of the Licensee' Position on -Item 4.2.Y '

The licensee states that his preventive maintenance-program for RTBs contains all the elements detailed in Section 2.1 of the SE. The licensee states that while maintenance is currently performed at six-month intervals, it is anticipated that the maintenance interval will be extended to 12 months after ore complete cycle of satisfactory operation using the new Mobil 28 j[ lubricated trip shaft bearings. We have determined the licensee position on Item 4.2.1 to be acceptable, provided the licensee confirms that the UVT l

device roller rivet-armature clearance is measured with the UVT armature down

, in the energized position, as recommended in IE Notice No. 85-58.

3.2 Evaluation of the Licensee's Position on Item 4.2.2 The licensee states that Arkansas Power and Light is a participant in and j

supports the activities of the B&W Owners Group for a Reactor Trip Breaker Reliability Monitoring Program, which is attempting to identify the most effective parameters to forecast breaker degradation or failure. That

' program includes collection of data on trip torque, breaker undervoltage trip

' response time and undervoltage trip pick up and dropout voltage. The licensee is providing these data to the B&W Owners Group Availability Group, which will perform trend analysis. We have determined the licensee position on Item 4.2.2 to be acceptable.

l 4. CONCLUSIONS Based on a review of the licensee responses, we have determined the licensee positions on Items 4.2.1 and 4.2.2 of Generic Letter 83-28 to be acceptable, provided the licensee confirms that the UVT device roller rivet-armature clearance is measured with the UVT armature down in the energized position,

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as recommended in IE Notice No. 85-58.

Dated: December 17, 1985 ^

The fo~llowing NRC personnel have contributed to this Safety Evaluation:

N. Romney and G. Vissing e

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