ML17300A808
| ML17300A808 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 05/04/1987 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML17300A807 | List: |
| References | |
| GL-83-28, NUDOCS 8705070254 | |
| Download: ML17300A808 (12) | |
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ENCLOSURE I SAFETY EVALUATION REPORT PALO VERDE NUCLEAR GENERATING STATION UNITS 1
2 AND 3 REACTOR TRIP SYSTEM RELIABILITY ITEMS 4.1 4.2.1 AND 4.2.2 OF GENERIC LETTER 83-28 1.
INTRODUCTION On July 8,
- 1983, the Nuclear Regulatory Comnission (NRC) 1ssued Generic Letter (GL) 83-28.
Th1s letter addressed intermed1ate-term act1ons to be taken by licensees and appl1cants aimed at assuring that a
comprehensive program of preventive maintenance and surve1llance test1ng 1s 1mplemented for the reactor trip breakers (RTBsg 1n pressurized water reactors.
In particular, Item 4.2 of the letter required the licensees
'and applicants ko submit a descr1pt1on of the1r preventive maintenance and surveillance program to ensure re11able reactor tr1p breaker operat1on.
The description of the submitted program was to include the follow1ng:
GL, Item 4.1 All vendor-recownended reactor tr1p breaker mod1f1cations shall be rev1ewed to ver1fy that either:
each mod1ficat1on
- has, in fact, been implemented, or a wr1tten evaluat1on of the technical reasons for not 1mplementing a mod1f1cation ex1sts.
GL, Item 4.2.1 A planned program of periodic ma1ntenance, 1nclud1ng lubrication, housekeeping, and other 1tems recommended by the equipment supplier.
GL, Item 4.2.2 Trend1ng of parameters affect1ng operation and measured dur1ng testing to forecast degradat1on of operat1on.
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- Company, the appl)cant for Palo 'Verde, Un)ts 1, 2 and 3, submitted responses to Items 4.2.1 and 4.2.2 of the Generic Letter on November 5,
1983, April 19,
- 1985, and April 3, 1986.
This report presents an evaluation of the adequacy of those responses and of the applicant's preventive ma1ntenance and surveillance programs for RTBs.
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- 2. l Per1od1c Maintenance Pr ram The primary criteria for an acceptable periodic maintenance program are contained in Maintenance Instruction GEI-50299EI, "Power Circujt Breakers.,
Types AK-2/2A-15, AK-2/3/2A/3A-25, AKU-2/3/2A/3A-25," and Service Advice 175-9.3S and 1759.20, by General Electric, and NRC IE Information Notice No. 85-58.
The NRC Staff'as reviewed these items and endorsed the.maintenance program 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 intervals that should be included in the licensee's RTB maintenance program are:
l.
Ver1ficat1on of breaker cleanl1ness and 1nsulation structure; all fore1gn mater1als, such as pa1nt, dust, or o1l, should be removed to prevent electrical breakdown between po1nts of d1fferent potent1al; 2.
Ver1ficat1on of breaker physical cond1tion, includin'g wir1ng insulat1on and terminat1on, all retaining r1ngs, pole bases, arc
- quencher, stat1onary and movable contacts, and t1ghtness of nuts and bolts; 3.
Verification of proper manual operation of the breaker, 1ncluding checks for excess1ve fr1ct1on, tr1p bar freedom, latch engagement, operating mechan1sm alignment and freedom, and undervoltage tr1p (UVT) device armature freedom; 4.
Ver1f1cat1on of the opt1mum freedom of the armature; 5.
Verif1cat1on of proper tr1p latch engagement as spec1f1ed 1n Serv1ce Advice 175-9.3S, Item gS2.
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6.
Ver1f1cat1on of undervoltage p1ck-up sett1ng, as spec1f1ed in Serv1ce Adv1ce 175-9.3S, Item ¹S3, and dropout voltage; 7.
Ver1f1cat1on that the tr1p torque required on the tr1p shaft 1s less than 1.5 pound-inches, as spec1fied 1n Service Adv1ce 175-9.3S, Item ¹S4; "Before" and "After" maintenance torque values should be recorded; 8.
Ver1f1cat1on of pos1t1ve tr1pping by checking the ad)ustment between the UVT device and trip paddle as spec1f1ed 1n Serv1ce Adv1ce 175-9.3S, Item ¹S5; 9.
Ver1f1cation of proper tr1p response time as spec1fied in Service Advice 175-..9.3S,. Item ¹S6; r
10.
Shunt Trip Attachment (STA) operation verif1cation; ll.
Examination and cleaning of breaker enclosure; 12.
Funct1onal test of the breaker pr1or to return1ng it to service.
2.2 Trend1n of Parameters Generic Letter Item 4.2.2 spec1f1es that the l1censee's preventative maintenance and surve1llance program is to 1nclude trend1ng of parameters affecting operat1on and measured during test1ng to forecast degradation of operation.
The parameters measured during the maintenance program descr1bed above which are applicable. for trending are undervoltage tr1p attachment dropout voltage, tr1p torque, and breaker response t1me for undervoltage tr1p.
The staff pos1t1on 1s that the above three parameters in addit1on to the breaker 1nsulation resistance are acceptable and recommended trend1ng parameters to forecast breaker operation degradat1on or failure. If subsequent experience indicates that any of these parameters 1s not useful as a tool to anticipate failures or degradation, the licensee may, w1th )ustification and NRC approval, elect to remove that parameter from those to be tracked.
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3.
EVALUATION 3.1 Evaluation of the A
11cant's Pos1t1on on Item 4.1 e
I The app11cant has conf1rmed that there are no app11cable vendor-recommended equ1pment mod1f1cat1ons.
The staff finds the appl1cant pos1t1on on Item 4.1 to be acceptable.
3.2 Evaluat1on of the A
11cant's Pos1tion on Item 4.2.1 The applicant's responses conf1rmed that the period1c maintenance program for both of the Reactor Trip Breakers (General Electr1c Hodel AKR-30 and Westinghouse Type DS-206) used. at Palo Verde 1ncludes all of the 1tems 11sted 1n Paragraph 2.1 of this SER, w1th the except1on of the measurement of breaker undervol tage tr1p response t1me; the app11cant
)ust1f1es net perform1ng that measurement by h1s dec1s1on to replace the undervoltage tr1p attachments at refuel1ng intervals.
The appl1cant's responses also stated that Palo Verde's per1od1c ma1ntenance on the RTBs 1
will be performed at s1x'month 1ntervals.
The staff finds that the applicant's
)ust1f1cat1on for not measur1ng the breaker undervoltage trip response time is satisfactory and that the Palo Verde per1od1c ma1ntenance program 1s acceptable.
3.3 Evaluat1on of the A
11cant's Position on Item 4.2.2 The applicant will trend undervoltaae trip attachment dropout voltage, trip force and breaker insulation resistance; he does not trend breaker undervoltage trip response time.
As noted in Paragraph 3.2, the applicant replaces the undervoltaqe trip attachment on a refueling interval basis.
The applicant will perform any appropriate preventive or corrective maintenance if the analysis of the trend data indicates need for such action.
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CONCLUSIONS Based on a rev1ew of the appl1cant's responses, the staff f1nds the appl1cant's pos1t1on on Items 4.l, 4.2.1 and 4.2.2 of Gener1c Letter 83-28 to be acceptable.
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