ML20138R198

SER Conditionally Accepting Util Responses to Generic Ltr 83-28,Items 4.2.1 & 4.2.2 Re Preventive Maint Program for Reactor Trip Breaker & Maint & Testing,Respectively

ML20138R198
Person / Time
Site:	Three Mile Island
Issue date:	12/12/1985
From:	NRC
To:
Shared Package
ML20138R186	List: ML20138R185 ML20138R198
References
GL-83-28, NUDOCS 8512310041
Download: ML20138R198 (5)

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SAFETY EVALUATION rep 0RT THREE MILE ISLAND NUCLEAR STATION. UNIT 1 TFACTOR TRIP SYSTEM RELIABILITY ITEMS 4.2.1 AND 4.2.2 0F GikERIC LETT R 83-28

1. INTRODUCTION On July.8, 1933, the 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 program of preventive maintenance and surveillance testing is implemented for the reactor trip breakers (RT8s)'in pressurized water reactors. In particular, Item 4.2 of the letter required the licensees and applicants to submit a. description of their preventive maintenance and surveillance program to ensure reliable reactor. trip breaker operation.

The description of the submitted program was to include the following:

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

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

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

Gpu Nuclear Corporation, the licensee for Three Mile Island Nuclear Station Unit 1 (TMI-1) submitted responses to the Generic Letter on November 8, 1983, and June 24, 1985. This report presents an evaluation of the adequacy of those responses and of the licensee's preventive maintenance and surveillance programs for RT8s.

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2. EVALUATION CRITERIA

?.1 periodic M31nten nce Prceran in2 primary criteria for an r.cceptable periodic maintenance program are contain.:d in !!:inteasaca instre: tion GEI-50 99EI*, Pcvar Circuit Breu'<ers,-n ;cs AK-2/05-15, 'M-2/.3/2.$./3A-25, AKU-2/3/2A/3A-25,' O.J Service Advice 115-9.3s and 115-3.20, oy Gencral Electric, and NRC IE Information h~otice No. S5-59. Tne NRC Staff, Equipment-Qualification Branch, has reviewed these items and endersed the maintenance program they describe.

The criteria include those items in.the General Electric instructions and advi,ories that relate to the safaty function of the breaker, supplementeel by these nassureme1ts shi:h i.:ust be takan to accumulate data fcr trending.

Tho:e items identified for caintenar.ce at siv month intervals that should

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be included 'in the licensee's RTS maintenance progran are:

1. Verification of breaker cleanliness and insulatico structure; all feroign materials, such as paint, dust, or cil, should be removed to prevent electrical breakdown between points of different pcter.ttal; 2.

Verif' cation of breaker physical condition, includir.g viring insulation and termination, all retaining rings, pole bases, arc quencher, stationary and movable contacts, and tightness cf nuts and bolts; 3.

Verif. cation of proper manual operatten of the breaker, including checks for excessive fricticn, trip bar-freedom, latch engagement, operating mechanism alignment and freedom, and ur.dervoltage trip (UVT) cavice armature freedom; 4

Verification of the optimum fice: m of the armature; i

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5. Verification of proper trip latch engagement as specified in Service Advice 175-9.3S, Item #S2.

6. Verification of undervoltage pick-up setting, as specified in Service Advice 175-9.3S, Item #S3, and drop'out

• voltage;

7. Verification that the trip torque required on the trip shaft is less 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 175-9.3S Item #55;

9. Verification of proper trip response time as specified in Service Advice 175-9.3S. Item #S6;

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 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 j in addition to the breaker insulation resistance are acceptable and recommended trending parameters to forecast breaker operation degradation l

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or failure. If subsequent experience indicates that any of these parameters 1,s not useful as a tool to anticipate failures or degradation, the licensee may, with justification and NRC approval, elect to remove that parameter from those to be tracked. .

3. EVALUATION 3.1 Evaluation of the Licensee Position on Item 4.2.1 The licensee intends to naintain a 6 month maintenance interval until

, sufficient information is available to assess the breaker performance.

That may change to a 12 month maintenance interval if performance found acceptable. The licensee confirmed that his periodic maintenance program includes the 12 items mentioned in paragraph 2.1 of this report. The staff finds the licensee position of Item 4.2.1 acceptable, provided the licensee confirms that the UVT 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 is a participant in the B&W Owners Group Reliability Monitoring Program. The licensee provides B&W with trending data of undervoltage device trip response time, trip shaft operating torque, undervoltage device pickup voltage, and undervoltage device dropout voltage. B&W will compile the licensee's data as well as the other member

• utilities and perform a trend analysis. The analyzed data will be reviewed by the Gp0N on a six month Dasis to determine if action is warranted. The staff finds the licensee position on Item 4.2.2 acceptable. .

4. CONCLUSIONS Based on a review of the licensee response!, the staff finds 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 e

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rivet-armature clearance is measured with the UVT armature down in the energized position, as recomended in IE Notice No. 85-58.

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