Text

Proposed Tech Specs,Adding Footnote to 3/4.7.10 to Allow Util to Conduct Visual Insp of Inaccessible Snubbers at Next Scheduled Refueling Outage
	ML19325F132
Person / Time
Site:	North Anna
Issue date:	11/01/1989
From:	; VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	;
Shared Package
ML19325F131	List: ML19325F130; ML19325F132;
References
	NUDOCS 8911140211
	Download: ML19325F132 (29)
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ATTACHMENT 1 i

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I PROPOSED TECHNICAL SPECIFICATIONS CHANGES I

NORTH ANNA UNITS 1 AND 2 l

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P REVISED PAGES FOR CURRENT NORTH ANNA r

1 TECHNICAL SPECIFICATION 0 i

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PL' ANT SYSTEMS Lo; o

3/4.7.10 SNUBBERS o LIMITING CONDITION FOR OPERATION

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.3.7.10 All snubbers utilized on safety related systems shall be OPERABLE.

For those snubbers utilized on non-safety related systems, each snubber shall be OPERABLE if a failure of that snubber or the failure of the non-safety related system would have an adverse effect on any safety related system.

APPLICABILITY: MODES 1, 2, 3 and 4.

(MODES S and 6 for snubbers located on systems required OPERABLE in those MODES).

ACTION:-

With one or more snubbers inoperable, within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> replace or restore the inoperable snubber (s) to OPERABLE status and perform an engineering evaluation per Specification 4.7.10.c on the supported component or declare the supported system inoperable and follow the appropriate ACTION statement for that system, j

SURVEILLANCE REQUIREMENTS 4.7.10 Each snubber shall be demonstrated OPERABLE by performance of the following. augmented inservice inspection program and the requiremente of

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Specification 4.0.5.

a.

Visual Inspections The first inservice visual inspection of snubbers shall be performed l

after four months but within 10 months of commencing POWER OPERATION and shall include the snubbers defined in 3.7.10.

If less than two (2) snubbers are found inoperable during the first inservice visual inspection, the second inservice visual inspection shall be performed 12 months 25% from the date of the first inspection.

Otherwise, i

subsequent visual inspections shall be performed in accordance with the,

i following schedule:**

No. Inoperable Snubbers Subsequent Visual per Inspection Period Inspection Period *#

0 18 months a 25%

1 12 months 25%

2 6 months 1 25%

3, 4 124 days i 25%

5.6,7 62 days 1 25%

8 or more 31 days i 25%

Early inspections (i.e., those performed before 75% of the current i

inspection period has elapsed) may be used to set new reference surveillance dates for the current inspection period.

However, the results of s9ch early inspections cannot be used to increase the current inspection period (period may onl stay the same or decrease as determined by the table in 4.7.10.a)y

The inspection interval shall not be lengthened more than one step at a time.

The provisions of Specification. 0.2 are not applicable.

NORTH ANNA - UNIT 1 3/4 7-28

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p-PLANT SYSTEMS x

3/4.7.10 SNUBBERS j

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, LIMITING CONDITION FOR OPERATION (Continued) i I

- T he visual inspection period established by the inspection performed in July j

i 1989_ may be nodified with a one-tine extension to perform the required snubber j

surveillance during the cycle 9 refueling outage. At that time the basis for i

calculating the inspection interval will be:

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No. Inoperable Snubbers Subsequent Visual i

per Inspection Period Inspection Period *#

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O 18 months + 25%

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1 12 months + 25%

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6 months + 25%

t 3, 4 124 days + 25%

5,6,7 62 days + 25%

n 8 or more 31 days + 25%

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This change is a one-time extension, and the option available expires at the completion of the cycle 9 refueling outage.

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NORTH ANNA - UNIT 1 3/4 7-28a q.

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NORTH ANNA i

MERITS TECHNICAL SPECIFICATIONS l

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MERITS FORMAT t

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This specification will be relocated to Chapter 16 (Technical Requirements) of the UFSAR in accordance with the MERITS program.

Therefore, no

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corresponding changes in the MERITS format have been included.

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I ATTACHMENT 2 DISCUSSION AND SAFETY EVALUATION i

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o Prw-d Technimi Somelfistion Channa No. 220 j

One time Extension of Surveillance iniarval for i

Visual inapaction of inaccansible Safety Ratated Snubbars l

l 1.0 INTRODUCTON i

Surveillance Requirement (SR) 4.7.10a specifies the visual inspection Interval for snubbers; SR 4.7.10b specifies the acceptance criteria for i

visual inspections. Based on the results during the last Unit 1 visual snubber inspection, conducted June 27 July 11,1989, the next inspection interval for innocessible safety related snubbers we.s determined to bo six j

months, or no later than February 23,1990.

i The proposed change will allow the required snubber surveillance to be performed during the next scheduled Unit i refueling outage, and i

eliminate the need for a mid cycle shutdown solely for the purpose of i

performing the surveillance. This safety evaluation provides technical justification for an one time extension of the current visuai inspection nterval from six months i 25%, to the Cycle 9 refueling outege (currently scheduled for March 8,1991).

2.0 TECHNICAL SPECIFICATIONS CHANGE The Technical Specifications must be revised in two places to implement the proposed amendment. The basis for this section remains unchanged.

A footnote " " ' will be placed after the first paragraph in Surveillance Requirement 4.7.10a and an explanation added. The explanation will read:

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"The visual inspection period established by the inspection l

performed in July 1989 may be modified with a one time l

extension to perform the required snubber surveillance during the cycle 9 refueling outage. At that time the i

basis for calculating the inspection interval will be:

No. Inoperable Snubbers Subsequent Visual c

oar Inmosction Parlod Insnaction Parlod 0

18 months + 25%

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12 months + 25%

2 6 months + 25%

3,4 124 days + 25%

5,6,7 62 days + 25%

8 or more 31 days + 25%

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l This change is a one time extension, and the option available expires at the completion of the cycle 9 refueling outage.

3.0 DISCUSSION The safety function of Surveillance Requirement 4.7.10e (visual inspection requirement) is to insure that no observable deficiencies exist with any snubber installation that would render a snubber inoperable. Snut,bers J

are required to ensure that the structural integrity of the reactor coolant j

system and other safety related systems is maintained during and following a seismic or other event initiating dynamic loads.

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Snubber Inservice inspection requirements consist of visual inspection and functional testing. Visual inspection is intended to detect potential impaired operability caused by leakage, corrosion or degradation due to environmental exposure. Functional testing typically involves removing the snubber and testing on a specially designed test stand to verify its ability to operate within specified performance limits. In general, functional testing is intended to provide a 95% confidenco level, that at least 90 percent of the snubbers are operab'e within acceptable limits.

The

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periormance of the visual inspection is a separate process which is complimentary to the functional testing program and provides additional j

confidence in snubber operability.

The proposed one time visual inspection extension proposed is based on providing a 95% confidence level, that 90 to 100 percent of snubbers are operable, as defined by the l

visual inspection accept;ijpe criteria, j

Current visual inspection acceptance criteria assure: (a) that there are no visual Indications of damage or impaired operability, (b) attachments to the foundation or supporting structure are secure, and (c) in those locations where snubber movemer t can be manually induced without disconnecting

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the snubber, that the snubber has freedom of movemont and is not frozen i

l up. Criterion "a" is verified during visual laspections by observing reservoir fluid level. Adequate fluid level indicates lack of leakage. Historically, as shown in an attachment, the majority of failures identified as a result of visual inspections are related to fluid level. Only rarely has a snubber been declared inoperable due to a mounting deficiency, which is the l

concern addressed by criteria "b" and *c".

The visual examination and functional test results for North Anna Unit 1, (Tables 1 A through 1F of the attachment) were reviewed and summarized by year and by failure / degrade mode for hydraulic and mechanic snubbers. The percent of snubbers which failed and the percent degraded were calculated and listed in separate summary tables (Tables 1G and 1 H). A total of eight tables were prepared. (Note: the tables in the attachment correspond in format to those found in e Brookhaven National Laboratory (BNL) report discussed below for ease of comparison.) The 1

1 tables illustrate that the percent failure rates found for visually examined i

snubbers at NAPS Unit 1 are low. The higher failure rates found for l

functionally tested snubbers indicate that failed snubbers are being identified primarily by testing and not by visual examination. The average l

percentage of visually examined and functionally tested snubbers compares favorably with the averages evaluated in the Snubber Utility Group (SNUG) data base.

The conclusions discussed above are i

consistent with those identified in the BNL report.

Virginia Power has coropared the visual inspection results obtained from h

data gathered on North Anna Unit 1 hydraulic and mechanical snubbers to j

that reported by Brookhaven National Laboratory (BNL) and submitted to i

the NRC in a June 12,1989 letter entitled, "Davalonment of Altornative Snubber Surveillance Raoulraments' Recommanded Interim Sn@hg Syveillance Plan " The results drawn from this report and the Virginia PC ser data are addressed in detail in an attachment.

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in brief, the BNL report indicates the acceptable number of inoperable snubbers for various facilities. The number is considered acceptable provided that the number of inoperable snubbers identified after a visual inspection of a 100% sample size is less than the valut in Column (c) in Table 2 of the BNL re sort. During the last inspection, two inoperable Unit 1 snubbers were ident fled; the upper limit of inoperable snubbers in the t

table is six. Thus, in accordance with the BNL guidance, the next inspection period may be increased to twice the past inspection period and the next inspection period may be skipped. Further, the snubbers in the group may be visually examined only every other outage as long as the results of the visual examination meet the requirements of Column (c).

Since the one time extension of 12 months is much shorter than that which I

could be technically justified (i.e.,36 months) based on the BNL report, this one time change appears to be well within the scope of the BNL guidance.

It is recognized that the NRC is currently evaluating the applicaollity of the i

methodology presented in the BNL report. Further, we understand that a generic letter is currently under consideration to address this issue.

However, the proposed omendment request focuses primarily on the l

schedular aspect of the testing, and North Anna Unit 1's visual inspection history, it is noted that North Anna's visual inspection history han been of limited value in identifying potential snubber concerns and thus a schedular delay would not have a significant impact in terms of timely Identification of snubber problems. The functional tact requirement, which remains unchanged, has historically been the better mechanism for identifying snubber enncerns. We do recognize the BNL work that has taken placa and note that North Anna Unit 1's snubber history compare.=

favorably with the results provided in the Brookhaven studies. This provides further assurance that a one time extension would continue to assure thnt the basis for the surveillance.cquirement was met.

4.0 10 CFR 50.59 EVALUATION When tested Sainst the criteria of 10 CFR 50.59, the proposed change

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was found it de no unreviewed safety questions. The basis for this determination,s u follows:

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The proposed action would not ircrease the probaollity of an accidant (i.e., earthquake) evaluated in the UF?AR because the probability of a seismic event is not affected by enubber testing.

The proposed amendment will have a negligible effect on accidenta caused by i

abnormal tranetent loads and on heatup or cooldown operat;on.

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The proposed action would no1 increase the consequences of an accident previously evaluated in the UFSAH because tile proposed r

amendment will continue to ensure that the required number of snubbers to periorm their safety re!cted function will be operable in the inspection Interval. This determination is supported by the conclusions drawn from the data gathered on NAPS hydraulic and mechanical snubbers and that reported in the BNL report.

l The proposed action might be viewed as increasing the probability of a f

malfunction of equipment important to safety bocause the additional time between inspections provides some incremental additional oppor1 unity for an undetected snubber failure to occur. However, this qualitative increase is acceptable because the historic cata both for North Anna Unit 1 and industry clearly illustrates that the number of degraded snubbers identified thro.;gh visual means has been very low.

l The proposed action would not create a possibility for a malfunction of equipment of a different type than any evaluated previously in the UFSAR because this proposed amendment doo3 not add or modify any t

existing equipment.

The proposed action would not increase the consequences of a f

malfunct on of equipment important io safety because the proposed l

change does not involve a modincation to any of the equipment l

affected or a change in operation of existing systems.

The proposed action would not create a possibility for an ace! dent of a different type than any evaluated previously in the UFSAR.

The proposed amendment does not add or modify any existing equipment.

The proposed action would not reduce any margin of safety as defined

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in the basis for any Technical Specifications because the proposed amendment will continue to ensure, with 95 percent confidence, that 90 to 100 percent of the snubbers are operable (i.e., the visual inspection

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acceptance cliteria will continue to be met).

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Based on the above, it is concluded that the proposed Technical Specircation does not constitute an unreviewed safety question.

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1.0 INTRODUCTION

The purpose of this evaluration is to provide technical justification for sn one time extension of the current visual inspection interval for inaccessible i

safety related snubbers from 6 months i 25%, uniil the Cycle 9 refueling outage.

l Virginia Power has reviewed and evaluated the information gathered to date on the NoNh Anne Unit I visual inspection snubber history, the potential likelihood ot nu..;*g a deficient snubber through visual inspection techniques, and the conclusions drawn from the Brookhaven National Laboratory Report, dated June 12,1989. Based on that review, sdequate assurance exists that an one time extension of the current visual inspection Interval for inaocessible safety related snubbers from 6 months 125%, until the Cycle 9 refueling outage (currently scheduled to begin i

December 27,1990) will provide a confidence level of 95% that at least 90% of the snubbers in the plant are operable at any time.

2.0 OPERATING PLANT DATA i

2.A SNUG DATA BASE The Snubber Utility Group (SNUG) was formed to share technical information about the maintenance, inspection and testing of snubbers. As part of its information exchange, SNUG has assembled a computerized data base that tracks the results of member utility snubber inspection and testing. The data base contains a summary by year of the number of snubbers tested, the numbers and types of failures and the criteria used for evaluation. Participation in this data base is voluntary and it is, therefore, not necessarily a complete set of records.

Of i5e fifty seven plants which participate in the SNUG data base, fifty havt provided updated oata during 1988 and the remaining seven plants have updated within the last two years. The remaining fifteen plants have chosen not to panicipate in the SNUG data base to date. While the data l

base does not contain all existing inspection and test data, i; is SNUG's judgement that the results indicated are generally reflective of snubber performance within the industry.

The SNUG data base information sent to BNL in January 1989 consisted of the following:

1.

Test and inspection reports formatted to print all data for a given year.

i (The previous report format only printed the data where failures or degraded conditions existed even though all dat3 was summed for I

the totals and grand totals).

2.

Data base file on floppy disk containing the data frnm the reports discussed in item 1 above.

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SNUG data base Program Users Manual.

The visual examination and functional test results ccntained in the data base were reviewed and summarized by BNL in tables by year and by l

failure / degrade mode for hyriraulic, large hydraulic and mechanical snubbers, in addition, the percent of snubbers which failed and the i

percent degraded were calculated and listed in separete summary tables, i

A W11 of eight tables were prepared and included in the BNL report as l

listwa below:

SNUG DATA BASE l

Iable D e s e rIo t io r, 1A Visual Examination Results Hydraulic Snubbers 1B Visual Examination Results Large Hydraulic Snubbers l

10 Visual Examination Results Mechanical Snubbers i

1D Functional Test Results Hydraulic Snubbers

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1E Functional Test Results Large Hydraulic Snubbers

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1F Functional Test Results Mechanical Snubbers i

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1G Visual Examination Results % Failed and % Degraded r

l 1H Functional Test Results % Failed Upon reviewing and analyzing the data in the tables, BNL found that there has been c significant increase in both the quantity and percentage of visually examined snubbers found to De failed / degraded in the last three years, it has been postulated that this increase may be due to one or more

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of the following: (c) the snubbers are approaching the end of their service livss; ('u) a changa in methodology in categorization end/or inspection techniques; and (c) plants having large numbers of failed / degraded snubbers have only recently started reporting to the data baso. BNL recommended that SNUG be requested to explain the reasons for the sharp increase in reported enubber visual examination failures / degrades during the last thre; years. We understand that an industry response is I

currently being prepared to address this recommendation.

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The nyerage percentage of visually examir,ed failed /dograd6d snubbers since 1975 is shown in Table 1G as:

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SNL'G DATA B&SE i

Highest %

i Failed is Ava. % Itallerj Ava % Dnararia Degraded Hydraulic Sr'ubbers 0.3%

2.0%

4.1(1986)

Large Hydraulic Snusbers 0.1%

4.1%

13.4 % (1986)

Mechanical Snubbers 0.0%

1.3%

P.5% (1986) j The average percentage of functionally tested failed snubbers since 1976 is shown in Table 1H as:

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SNUG DATA BASE i

Ava. % Failed Hlaheat % Egugd l

Hydraulic Snubbers 12%

39 % fj976)

Large Hydraulic Snubbers 25%

84 % (1982)

Mechanical Snubbers 10%

18% (1984)

I The percent failure rates found for visually examined snubbers are very low. The high failure rates founo for functionally tested snubbers indicate that failed snubbers are being found primarily by testing and not by visual examination.

28. North Anna Nuclear Power Station Unit 1 Current visualinspection acceptance crit 9rla assure: (a) that there are no visual indications of damage or impaired operability, (b) attachments to the foundation or supporting structure are secure, and (c) in those locations where snubber movement can be manually induced without disconnecting the snubber, that the snubber has freedom of movement and is not frozen l

up. Criterion "a"is verified during visual inspections by observing reservoir fluid level. Adequate fluid level indicates lack of leakage. Historica'ly, as shown in the attached Tables 1 A through 1F, the majority of failures identified as a result of visual inspections are related to fluid level. Only

l rarely has a snubber been declared inoperable due to a mounting j

det:ciency, which is the concern addressed by criteria 'b' and "c".

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i Tables formatted in the same manner as the BNL tables have been j

created for North Anna to better illustrate and compare the plant specific Informction with that in the BNL report. The visual examination and functional test results for North Anna Unit 1, shown in Tables 1 A through 1F, have been reviewed and summarized by year and by failure / degrade mode for hydraulic and mechanic snubbers, in addition, the percent of l

snubbers which failed and the parcent degraded were calculkted and i

listed in separate summary tables ' Tables 1G and 1H). A total of eigM I

tables were prepared as listed below (attached):

NORTH ANNA POWER STATION UNIT 1 j

f lable DeaeriotIoa 1A Visual Examination Results - Hydraulic Snubbers j

f 1B Visual Examination Resuys Large Hydraulic Snubbers 10 Visual Examination Resul' Mechanical Snubbers 1D Functional Test R9sults Hydraulic Snubbers t

1E Functional Test Results - Large Hydraulic Snubbers i

1F Functional Test Results Mechanical Snubbers 1G Visual Examination Results % Failed and % Degraded 1H Functional Test Results - % Failed The aver ge percentage of visually examined fallad/ degraded snubbers at NAPS Unit 1 since 1978 is shown in Table 1G as:

NORTH ANNA POWER STATION UNIT 1 Highest %

Failed &

Avg. % Failed Avg. *4 Degraded Degraded Hydraulic Snubbers

<0%

< O'.<

< 0% (1981)

Large Hydraulic Snubbers 0%

0%

NA Mechanical Snubbers 0%

0%

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O' The average percentage of functionally tested failed snubbers at NAPS Unit t since 1978 is shown in Table 1H ss:

NORTH ANNA POWER STATION UNIT 1 Ava. % Failed Hichent % Failed Hydraulic Snubbers 8%

16%

(1982)

Large Hydraulic Snubbers 21 %

40 %

(1983)

Mechanical Snubbers 0%

0%

NA The percent failure rates found for visually examined snubbers at NAPS Unit 1 are very low. The high failure rates found for functionally tested snubbers indicate that failed snubbers are being identified primarily by testing and not by visual examination. The average percentage of visually examinod and functionally tested snubbers compares favorably with the averages evaluated in the SNUG data base. The conclusions discussed above are exactly those identified in the BNL report.

Conclusions Based on 'he information outlined above, the following conclusions support an one4ime extension of the NAPS Unit 1 inaccessible safety related snubber surveillance interval:

1)

The percent failure rates for visually examined snubbers are very low.

2)

The percent failure rates for functionally tested snubbers are significantly higher which indicate that failed snubbers are being found primarily by l

testing and not by visual inspection. Virginia Power will continue to conduct functional testing in accordance with the current T6chnical i

Specifications.

3)

The curient NAPS Unit 1 sample plan for functional testing and interim visual inspection of snubbers meets the NRC's requirements that at least l

90 to 100 percent of the snubbers be demonstrated to be operable, with 95% confidence level.

l 4)

A large sample sirs (t00%) of snubbers was previously visually inspected I

at NAPS Unit 1 with acceptable results (only two failures) therefore, the possibility of undisecvered failure is low and the function of the total population of snubbers is reasonably assured by functional test requirements.

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NORTH ANNA UNIT 1 SNUBBER INSPECTION INFORMATION FORMATTED IN THE BNL-STYLE TABLES 1 A THROUGH 1H l

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Tamr2 la-SWWERRY OF CIGNIFICANF TISNaL EERNINETION ErESOLTS

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1 1

1 YSa8 m 9

9 9

9 Tot.at 7

7 7

8 8

8 FAILURE MODE 5

6 7

8 9

9 1

2 3

4 5

6 7

8 TOTAL NUM83ER OF SNUSSERS 298 293 298 298 298 298 3@

3%,

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l NUMBER OF SNUMBERS INSPECTED l

298 293' 298 298 298 298 300 1*

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OTHER (Rod Eve Bound by Pipe Clarp) 1 31 JZ i

F RESERVOIR EMPTY 1

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3 AM D4MAGED I

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LD NO LEAK i

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UE Insufficient SEAL LEAK 1

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Fluid FITTING LEAK 2

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Subtotal 2

25 9

2 1

13 46 I

99 D

CORROSION E

DAMAGED (Reservoir) 2 2

l GM LEAK (RESERVOIR NOT EMPTY)

RO LOOSE / MISSING PARTS AD FITTING LEAK DE Low Fluid NO LEAK i

E SEAL LEAK i

D OTHER I

PLUG IN VENT LEAK (RESERVOIR EMPTY)

Subtotal 2

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L 4 21 2sl 111 1 12 1 i i 13 i L 461 1 l-toi 1

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Visual inspection of snubbers was not reouired in 1988; however, during

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routine maintenance activities the part was discovered to be uncovercJ.

This failure was counted against the 1989 results.

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J Added jam nuts at all threaded load studs per Grinnell; not considered I

operabilit, probles:.

t TABLE ID- - *Y OF CIGNIFICANT VIEWEL EIBIEIIIATION RE3gLTS FOR LAEGE BYBEAULIC 355335E5 (GREATER Team S In stanETER OR 138 mIFs) g1 1

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1 1

1

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1

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1 1

4 YEAR _

9 9

Tetal 7

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8 8

8 fFAILDRE30005 5

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8 9

8 1

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4 3

6 7

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TOTAL NUMBER OF SNUBBERS 36 36 36 36 36 36 36 NA i

i NUMBER OF SNUBBERS INSPECTED u

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36 36 36 252 OTHER F

RESERVOIR EMPTY

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16 24 AM DAMAGED j

IO LOOSE / MISSING PARTS LD NO LEAK UE Insufficient SEAL LEAK

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CORROSION i

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QO LOOSE / MISSING PARTS AD FITTING LEAK 1

DE Low Fluid NO LEAK l

E SEJ.L LEAK j

D OTHER (rto, une )

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Comanon Accumulator (Reservoir) serves as snakeup I

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s r b E

A E

6 A

I a l

M 5 0 F

3 0

m 3

' )

g 2

O Q to O Q to la 19 5

J 4

l w

< S EQQW EOQW

{

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=

TABLE ID-5WWERY OF CIGNIFICANF MONEL EISEEIMO2 TEST RESULTS FOR NYBR&BLIC - (WF TO S* IN BI4fETER) 1 1

,1 1

1 1

,1

,1 1

1 1

1

,I

,I L i

YEAR _

9 9

Total 7

7 7

8 8

8 I

FAILURE Ness 5

6 7

ft 9

0 1

2 3

4 5

6 7

8 i

i.

4 Y

l j

TOTAL NUMBER OF SNUBBERS 447 447 447 447 447 M4 f

NUMBER OF SNUBBERS INSPECTdD 1

32 447 31 20 15 546

's OTHER

{

T'LEED DAMAGED

{

HIGH ACCELERATION l

HIGH BLEED 1

17 18 HIGH DRAG - BREAKANAY l

i HIGH DRAG - RUNNING HIGH DRAG l

5.

6 l

l HIGH LOCKUP - SEAL RELATED HIGH LOCKUP l

HI/LO AUTO LOCKUP

~

i LOCKED UP LON ACCELERATION i

(

LON FLUID LON LOCKUP 14 14 LON/MO BLEED 4

35 2

41 NO ACTIVATION i

NO LOCKUP a5~ab FAILURE 1

l

[ VALVE CHATTERING i

I esass TUFab 1

i 1

11 1 I

I I

s1 1

I I

Combination of accessible & inaccessible.

NOTE: Feilure mode numbers may be combinations front same test.

i i

i l

1

-~.

. - =

TABLE 10-SENGERY OF CIGNIFICENT FEMCTIGEAL RZABEIERTION TEST RESULT 5

~

FOR (GREATER TERN S* IN DIASETER OR 130 KIPS)

~

i

'd i

1

,1 1

1 1

1 l

-l N

YEAR _

~

9 9

Totes 7

7 7

8 S

S S

S

- FAILURE Bigot 5

6 7

8 9

9 1

2 3

4 5

6 7

8 l'

o n

TOTAL NUMBER OF SNUBBERS 36 36 36 NA i

NUMBER OF SNUBBERS INSPECTED 5

14 19 I

OTHER (No fluid in valve block) 9 2

ELEED DAMAGED

{

HIGH ACCELERATION 1

HIGH BLEED HIGH DRAG - BREANANAY t

HIGH DRAG - RUNNING HIGH DRAG MIGH LOCKUP - SEAL RELATED i

l HIGH LOCRUP i

Nf/LO AUTO LOCKUP I

LOCKED UP I

F LOW ACCELERATION i

i LOW FLUID l

LOW LOCKUP i

4 LOW /NO BLEED 7

7

[

NO ACTIVATIOff l

NO LOCKUP SEAL FAILURE VALVE CHATTERING Istamp foraL i

I i

I 1

i i

I 2g g7 g g

9 l

NOTE:

In 1989, per DCP 86-09, the M111waukee L.B. Snubbers with external accumulators f

and fluid lines were deleted and/or replaced w/ Taylor's whic.h have all internal fluid supply.

I 1

-... ~

- _ _ _ - ~ _ _ _ _., _ _ - -. - - - -.. - _ _ _ _ _ _,

o I

TABLE 1F-SENGERRY OF BIGNIFICANT FENCTIOERL EIANIM& TION TEST RESULTS FOR secuhu1 CAL sugassas

'N 1

9}9 1

1 1

1

,1 1 11

,1 1

' i YE&B _

9 9

Total 4

7 7

7 8

8 8

i FAILURE MODE 5

6 7

8 9

0 1

2 3

4 5

6 7

e 1

i TOTAL NUMBER OF SNUBBERS 4

4 M

NUMBER OF SNUBBERS INSFiin iw A

8 l

{

OTHER j

ELEED l

DAMAGED

_HIGH ACCELERATION HIGH BLEED

/

HIGH DRAG - BREAKAWAY HIGH DRAG - RUNNING i

MIGH DRAG I

HIGH LOCKUP - SEAL RELATED l

HIGH LOCKUP 5

l HI/LO AUTO LOCKUP l

LOCKED UP

[

LOW ACCELERATION l

LOW FLUID LOW LCCKUP j

LOW /NO BLEED NO ACTIVATION NO LOCKUP 1

l SEAL FAILURE i

VALVE CHATTERING 5

t l

1eaAmp

..L i

1 i

i i

1 i

i I

I I

I L

i I

a NOTE: No functional test failures.

l,

[

r i

i i

I

.. s -.. -.

- -.--..-.= --... -..-

Tasts l a rsac e FmItas a m Bea m -

VIM NW i

1 1

,1 1

1 1

1 I

i fRRE 9

9 9

9 gag.g o

7 7

7 8

8 8

8 e

3 e

a e

a FAILURE IWSB 5

6 7

8 9

9 1

2 3

4 5

6 7

8 Ages TOTAL NUMBER OF SNUBS---

I I

i l

1l P

F g

298 298 298 298 296 298 3W JW l

.NUNBER OF SNUB 9 ;; i-Kisy 298 298 298 298 295 295 JW I

l N

_ NUMBER FAILED I

Y NUMBER DEGRADED 1

1 2

2 2

)

D TOTAL FAILED E DSGRAvsy 3

1 1

4 R

PERCENT FAILED n

A PERCENT DEGRADED o

{

U PERC5 i FAILED & DBGRADED i

L j

I l

C l

TOTAL NUMBER OF SNUBBERS 36 36 36 16 16 16 1A l

NUMBER OF SNUBBERS INSFKsmy 36 36.

36 36 36 36 36.

j N

NUMBER FAILED l

Y NUMBER DEGRADED LD TOTAL FAILED & E--2";3 -

AR PERCENT FAILED DA PERCENT DEwsADED j

GU PEin.

. FAILED & seuuAsis o

o o

l EL l

I c

j iWi&L M OF SNUSSERS 4

4 4

4 0

]

NUMBER OF SNUBBERS Issa -Ks my a

i t

1 1

1 i

W IRBSEE FAILED E

_ - = DAGREE E-C 7072L F11 LED & DEGR&DED N,PEREEIff FAILED

)

A FEan:ss? DEGRADED

}

O FERCEIIT FAILED & DOGRADED o.

O oI o

n n

i I

l C

Counted w/'89 Inspection.

A 7

L i

1

TRELE BE N FalLEB emuumamme MMBL TM BNTS

~

I 1

1 1

1

,1 1

11, I j1 1

1 1

YB&B _

9 9

Total 7

7 7

8 8

-8 8

8 FAILORE NOWE 5

6 7

8 9

9 1

2

'3 4

5 6

7 8

ages TOTAL NUMBER OF SNUBS M

&&7

_447 447 447 44]

> NUMBER OF SNUBB m i

_ Ki sD 1

32 447 31 20 11:

646 j

N NUMBER FAILED 0 I 5

1 46, 2

0 0

53 Y

D D

PERCENT FAILED l

l l

1 02 I I

I 116r I l iar l 6t l or I ni l _ l A

U j

L i

I C

l TOTAL NUMBER OF SNUB 8ges 36 Je j

NUMBER OF SNUSSERS ImmFKssu s

14 19 l

N NUMBER FAIL M 2

2 4

i Y

l LD l

AO PERCENT FAILED l

I I

1 I

I I

I I40Z1 1 14d I

j RA GU i

EL l

I C

ivi-AL NUMBER OF SNUBBERS 4

4 i

I

, NUMB 5pt OF SNUBSERS INSPECTED I

4 4

l M

NUMBER FAILED l

0 0

E C

l N

PsEsaws FAILED 1

1 I

I I

l l

l 02 1 l

l oil f

l i

N i

I l

C l

A j

L

1.

.,1

'4 i

o i

i I

i t

?

f i

ATTACHMENT 3 i

f 10 CFR 50.92 EVALUATION l

t l

l l

s r

l I

i i-l i

r l

f t

t t

1

't i

i i

i t

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'O o

9

=

10 CFR 50.92 EVALUATION The proposed change in the North Anna Technical Specifications does not involve a significant hazards consideration. The basis for this determination is as follows:

The proposed change v'll allow the required visJal surveillance for inaccessible mty relatt i snubbers to be performed during the next scheduled refueling uviage, and eliminate the need for a mid-cycle shutdown for the purpose of performing the surveillance.

This schedular adjustment does not involve a significant increase in the probability or consequences of an accident previously evaluated g

because the accident conditions and assumptions are not affected by the proposud Technical Specification Change. The additional time u

bstween surveillance could o witatively be considered to increase the probability of an undetected failure, however, both the plant-b specific and generic industry data illustrate that the number of failures p-identified through visual inspection is acceptably low and warrant the one-time incremental increase in the surveillance interval.

=

The possibihty of a new or different kind of accident from any accident previously evaluated is not created. The proposed change does not add to or modify any equipment or system design nor does it involve m

any changes in the operation of any plant system. The absence of a hardware change means that the accident initiators remain unaffected, so no unique accident probability is created.

The proposed amendment does not involve a significant reduction in the margin of safety as defined Iri the basis for any Technical Specifications because the proposed amendment will continue to m_

ensure, with 95% confidence, that 90 to 100 percent of the snubbers are operable. This conclusion is supported by the calculations reported in the Bf 4L report. Further, since a large sample size (100%)

r.c of snubbers has been previously visually inspected with acceptable results, the oossibility of an undiscovered failure is low and the function of the total population of snubbers is reasonably assured.

b L

E W

mm

'.

ML19325F132

Text

1.0 INTRODUCTION

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