ML20236T517

Proposed Tech Specs Re one-time Extension to Functional Test Frequencies for Hydraulic & Mechanical Snubbers

ML20236T517
Person / Time
Site:	Oconee
Issue date:	07/20/1998
From:	DUKE POWER CO.
To:
Shared Package
ML15112A669	List: ML20236T517
References
NUDOCS 9807280236
Download: ML20236T517 (14)

Text

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ATTACHMENT 1 4

TECHNICAL SPECIFICATION Remove Page Insert Page 4.18-2 4.18-2

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9807280236 980720 l PDR ADOCK 05000269 i P PDR

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l and extending the piston rod in the tension mode direction. All snubbers connected to an inoperable common hydraulic fluid reservoir shall be counted as inoperable snubbers.

Snubber operability will be verified in accordance with the following schedule:

No. Inoperable Snubbers Subsequent Visual per Inspection Period Inspection Period 0 18 months 2 25%

1 12 months 25 %

2 6 months t 25%

3,4 4 months i 25%

5,6,7 2 months 25 %

28 1 month 2 25%

Note: (1) The required inspection interval shall not be lengthened more than two steps per inspection.

(2) Snubbers may be categorized in two groups, " accessible" or " inaccessible,"

based on their accessibility during reactor operation. These two groups may be inspected independently according to be above schedule.

(3) Hydraulic and mechanical snubber inspection schedules are independent.

4.18.2 The seal service life of hydraulic snubbers shall be monitored to ensure that the seals do not exceed their expected service life by more than 10% between surveillance inspections.

The maximum expected service life for the various seals, seal materials, and applications shall be estimated based on engineering information, and the seals shall be replaced so that the maximum expected service life is not exceeded by more than 10% during a period when the snubber is required to be OPERABLE. The seal replacements shall be documented and the documentation shall be retained in accordance with Specification 6.5.1.m.

4.18.3 At least once every 18 months', a representative sample, a minimum of 10% of the total of I hydraulic snubbers in use in the plant, shall be functionally tested either in place or in a bench test. For each hydraulic snubber that does not meet the functional test acceptance criteria of Specification 4.18.4, an additional minimum of 10% of the hydraulic snubbers shall be functionally tested until none are found inoperative or all have been functionally tested.

The representative sample selected for functional testing shall include the various j configurations, operating environments and the range of size and capacity of hydraube {

snubbers. The representative sample shall be selected randomly from the total population l

of safety-related hydraulic snubbers.

'A one-time extension of the snubber functional test frequency to a maximum of 25 months is allowed for Oconee Unit 3 during operating cycle 17. This extension also applies to the functional testing of mechanical snubbers required by Technical Specification 4.18.5. j Oconee 1,2 and 3 4.18-2 Amendment No. (Unit 1)

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Amendment No. (Unit 2) >

Amendment No. (Unit 3)

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TECHNICAL SPECIFICATION MARKUP i

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and extending the piston ned in the tension mada direction. All anubbers connected to an inoperable comenon hydraulic auld reservoir shau be oounted as inoperabie snubbers.

Snubber operability wHl be verified in acconiance with the followin6 schedule:

No.InoperableSnubbers Subsequent Visual perInspection Pedod Inspection Pedod 0 18 anonths *2S%

1 12 months *2S% -

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6 months

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3,4 4 months *25%

5,6,7 2 months *2S%

28 1 month *25%

Note: (1) h requhed inspection interval shall not be lengthened more than two steps perinspection.

(2) Snubbers may be categodzed in two groups, "a===fhie" or 'ipm---sble!'

based on their a===Ihility durly reactor operation. 'Ihese two groups may be htW Indeperyently aseding to be above schedule.

(3) Hydraulic and me&anical snubber, inspection s&edules are independent.

4.18.2 The seal service life of hydraulic snubbers shall be monitored to ensure that the seals do not av-d their expected service life by more than 10% bcta;;a surveillance laaaa'+ tons.

"Ihe maximum aw;-*ad service life for the vadous senk, seal matedals, and applications shall be estimated based on erghaLg; information, and the seals shall be replaced so that the maximum aw;=*ad service life is not ev-ded by more than 10% during a pedod wheri the snubber is required to be OPERABLE. The seal rep 1=<== ants shan be documented and the documentation shall be retained in accordance with Specification 6.S.I.m. -

4.18.3 Atleast once every 18 ivw.tative sample, a minimum of 10% of the total of [

hydraulic anubbers in use in the plant, shan be functionally tested either in place or in a bench test. For each hydraulic snubber that does not meet the functional test acceptance l

' criteda of Spar 46ation 4.18.4, an additional minimum of 10% of the hydraulic snubbers shall be functionally tested until none are found inoperative or aH have been functionally tested.

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& representative sample selected for functional testing shall include

• the vadous configurations, operating environments and the range of size and capacity of hydraulic snubbers, h representative sample shall be selected randomly from the total population of safety-related hydraulic snubbers. -

\ A cust-Tm(. L YTE"s'0" of Tt*e scuoscor cancisounv7G s7 Moucows ro g OcOMil N"0 but Mb OM/grig r1Avinun or 25 hostnf is Anowco FQt -

cyca n. Ta<s e mussoa mso Mnas rvrae raucroouacnviu er ttcwtwwu suusstes Gaaotto by TrcHuscu, snccertenvou eigg Oconee 1,2, and 3 4.18-2 Amendment No228(Unit I)

Amendment No229(Unit 2)

Amendment No.225(Unit 3)

. In addition to the regular sample, hydraulic snubbers which failed the previous f'anctional test shall be ratested during the next test period.

If a spare hydraulic snubber has been installed in place of a failed i

hydraulic snubber, then both the failed hydraulic snubber (if it is .

repaired and installed in another position) and the spara hydraulic

) snubber shall be ratested. Test results of these hydraulic snubbers

!' may not be included for the re-sampling, and failures shall not require i additional testing of other snubbers.

I-If any hydraulic snubber selected for functional testing either fails to lockup or fails to move, i.e., frozen in place, an engineering evaluation will be performed to determine if the mode of failure could affect other snubbers of the same design. If this is determined, then reporting requirements under 10CFR Part 21 will be examined for applicability.

When a snubber is found inoperable, an engineering evaluation will be performed in accordance with appropriate Station Procedure.

4.18.4 The hydraulic snubber functional test shall verify that:

1. Activation (restraining action) is achieved within the specified range of velocity or acceleration in both tension and compression.

2. Snubber bleed, or, release rate, where required, is within the

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specified range in compression or tension. For hydraulic snubbers specifically required not to displace under continuous load, the ability of the hydraulic snubber to withstand load without displacement shall be verified.

l 4.18.5 The requirements of Specification 4.18.3 shall also apply to mechanical I enubbers commencing with the Unit 2 refueling outage for Cycle 7 )

operation.

The mechanical anubber functional test shall verify that:

1. The force that initiates free movement of the snubber rod in either tension or compression.is less than the specified maxistum drag force.

2. Activation (restraining action) is achieved within the specified range of velocity or acceleration in both tension and compression. (Measuring the time required to travel a known distance, under load, is an acceptable method.) j

3. Snubber release rate, where required, is within the specified range in compression or tension. For snubbers specifically required not to displace under continuous load, the ability of the snubber to withstand load without displacement shall  ;

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pog mfonMEROM ONc4 A 101/101/98 4.18-3 10/19/81

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Attachment 3 f

Technical Justification

Background

This license amendment request became necessary due to two forced outages and one prolonged shutdown of Oconee Unit 3.

These delays moved the refueling outage window for oconee Unit 3 to the period between late August 1998 and mid-October 1998. Delaying the beginning of the outage until October 13, 1998, involves a coast down but avoids a concurrent refueling outage with Catawba Unit 2 allowing better utilization of resources needed for both refueling outages. The outage begins when the generator breaker is opened.

As a result of the outage schedule change and the lengthened duration of the operating cycle, the Technical Specification surveillance requirements were reviewed to ensure compliance with the Technical Specifications. This review indicated that seven instrument channel calibrations and a manual stroke test of two valves were required to be completed before the refueling outage. A request to extend the surveillance intervals for these surveillance was submitted to the NRC on July 16, 1998.

It'was subsequently determined, during a review performed as a part of the Oconee Recovery Plan initiative, that functional tests of hydraulic and mechanical snubbers had not been identified for inclusion in the July 16, 1998, amendment request. Duke has investigated the apparent causes for not including these two surveillance in the earlier Technical Specification amendment request. This investigation found that these surveillance had been inappropriately coded in the Work Management System (WMS) as

" condition based" requiring only a refueling outage rather than being coded for the 18 month interval required by Technical Specifications. Since the review performed for the July 16, 1998, amendment request was based on an 18 month interval calculated by the WMS, these surveillance were overlooked. As a follow-up to this investigation, all other Unit 3 " condition based" surveillance were reviewed and it has been verified that all surveillance needing an extension have been identified. Duke has initiated a investigation to determine the root cause of these omissions. Appropriate corrective action will be implemented.

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' Attachment 3 Technical Justification L 1 Technical Specification Section 4.0 specifies an 18 month surveillance frequency as having a maximum-interval of 22 months and 15 days. Technical Specification Sections 4.18.3 and 4.18.5 establish the surveillance requirements for hydraulic and mechanical type snubbers, respectively. The requirements of both sections are identical in that they both require functional testing of a representative sample, a minimum of 10 percent of each snubber type (i.e.,

hydraulic or mechanical), at least once every 18 months.

The maximum surveillance interval will be exceeded on August 27, 1998, for both the hydraulic and mechanical snubber functional tests. The lengthened operating cycle will result in the surveillance interval for these tests being exceeded before the start of the refueling outage.

Snubbers are used as supports and restraints for piping systems and components. The function of snubbers is different from rigid supports ~and restraints since they provide no load path or force transmission during normal plant operations but function as rigid supports when subjected to dynamic transient loads, i

To verify that a snubber can operate within specific performance limits, Oconee Nuclear Station (ONS) performs functional testing that involves removing the snubber and l testing it on a specifically designed test stand. Hydraulic snubbers are tested for activation velocity and bleed rate, and mechanical snubbers are tested for drag and acceleration rate. Ten percent of the total snubber population are tested during each refueling outage. ONS separates the

,, snubber population into hydraulic and mechanical and tests a minimum 10% representative sample from each group. The l representative sample includes the various configurations, operating environments and the range-of size and capacity of l . snubbers. For each snubber that does not meet the i

functional test acceptance criteria, an additional minimum 10% sample of that snubber type will be tested until none is found inoperable or all the snubbers of that type have been functionally tested. Functional testing in this manner provides a 95% confidence level that 90% to 100% of the snubbers operate within the specified acceptance limits.

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Technical Justification l

The snubber functional tests cannot be performed at power ,

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l sample of randomly selected snubbers of each snubber type, l l

A significant portion of the snubbers that would be selected are inside containment at locations that are inaccessible due to radiation and/or high temperatures. These snubbers  !

can only be functionally tested at Cold Shutdown.

Considering the previous hydraulic and mechanical snubber functional test dates and the need to operate until October i 13, 1998, the maximum allowed interval of 22 months and 15 days would be exceeded.by 2 months and 1 day. Therefore, an extension is needed.

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Description of the Technical Specification Change i This Technical Specification amendment request involves a l one time change to the function test frequency for hydraulic and mechanical snubbers.

To support the operation of Oconee Unit 3 to the scheduled  ;

refueling outage, a one-time extension of the interval )

between surveillance to a maximum of 25 months is necessary )

for the hydraulic snubber functional test of Technical Specification 4.18.3. This change also applies to Technical ;

Specification 4.18.5 (mechanical snubber functional tests) i which refers to and uses the surveillance interval of l Technical Specification 4.18.3.  !

Technical Justification The Technical Justification for this amendment request is in two parts to separately address the hydraulic and mechanical snubbers.

Hydraulic Snubbers A review of the previous two performances of the Oconee Unit  !

3 hydraulic snubber functional tests found no failures and the performance of all tested snubbers was within allowable tolerances. In each case, the representative sample which were functionally tested consisted of 10 % of the hydraulic 3

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I Attachment 3 Technical Justification snubber population since the tested snubbers met acceptance criteria.

The latest visual inspections of the Unit 3 hydraulic snubbers' revealed no evidence of damage or potential problems with any snubber and provide added confidence that

.the' hydraulic. snubbers will-remain operable during the extension.

The performance history for the last two functional tests of safety-related hydraulic snubbers at Oconee Units 1 and 2 L was also reviewed. This review found no inoperable hydraulic snubbers of the 42 functionally tested.

A review of industry operating experience data found no information which suggests a problem with the safety-related hydraulic snubbers installed at ONS.

Oconee Unit 3 has experienced no seismic or severe dynamic event that would challenge the snubbers' capability to l remain operable.

Based on the past performance of the hydraulic snubbers and industry experience with similar snubbers, there is a high l level of confidence that no adverse effects on the l operability of the snubbers, or the systems or components l supported by;those. snubbers, will occur as a result of the brief extension. Thus, a one-time extension of the hydraulic snubbers to a maximum of 25 months should not result in degradation of the capability of the snubbers to  ;

l operate within the specified acceptance limits.  !

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Mechanical Snubbers j The. previous two performances of the Oconee Unit 3 mechanical snubber functional tests were reviewed. The <

. earliest functional test performed during the end-of-cycle  !

L 15. refueling outage identified one-mechanical snubber I

' failure in the.first 10 % sample tested. As the result of l the failed snubber, a second 10 % representative sample of i

-mechanical snubbers was tested. There were no failures in  ;

the second sample test-group. Other than the one failed j snubber, there were no failures and the performance of all other tested snubbers was within allowable tolerances.

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Technical Justification Functional testing in this manner provides a 95% confidence level that 90% to 100% of the snubbers operate within the specified acceptance limits.

The latest performance of the functional tests performed during the end-of-cycle 16 refueling outage found no failures. Further, the performance of all tested snubbers was within allowable tolerances. The representative sample which was functionally tested consisted of 10 % of the mechanical snubber population since the tested snubbers met acceptance criteria.

The latest visual inspections of the Unit 3 mechanical snubbers revealed no evidence of damage or potential problems with any snubber and provide added confidence that the mechanical snubbers will remain operable during the extension.

The performance history for.the last two functional tests of safety-related mechanical snubbers at Oconee Units 1 and 2 was also reviewed. This review found two failures out of the 56 snubbers tested. Engineering evaluation of the affects of these failures determined that the snubber failures did not cause the supported systems to be inoperable.

A review of industry operating experience data found no information which suggests a problem with the mechanical snubbers installed at ONS.

Oconee Unit 3 has experienced no seismic or severe dynamic event that would challenge the snubbers' capability to remain operable.

Based on the past performance of the mechanical snubbers and industry experience with similar snubbers, there is a high level of confidence that no adverse effects on the operability of the snubbers, or the systems or components supported by those snubbers, will occur as a result of the brief extension. Thus, a one-time extension of the mechanical snubbers to a maximum of 25 months should not result in degradation of the capability of the snubbers to l operate within the specified acceptance limits, l

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Attachment 3 ,

Technical Justification Based on the information in this attachment and the Bases of the Technical Specifications, Duke Energy Corporation concludes that the proposed amendment will not present an undue risk to public health and safety.

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ATTACHMENT 4 NO SIGNIFICANT HAZARDS CONSIDERATION EVALUATION This proposed change has been evaluated against the standards in 10 CFR 50.92 and has been determined to involve no significant hazards, in that operation of the facility in accordance with the proposed amendment would not:

1. Involve a significant increase in the probability or consequences of an accident previously evaluated?

No. A review of the previous two hydraulic and mechanical snubber functional tests, discussed in this amendment request concluded that no adverse effects should occur as a result of the one-time extension. As a consequence, there should be no adverse affects to the piping systems and components which are restrained by snubbers for seismic and pipe whip events.

There is a high level of confidence that the snubbers should be available to perform their intended function during the requested extension period. Thus, the probability and consequences of an accident previously evaluated will not be significantly increased.

2. Create the possibility of a new or different kind of accident from the accidents previously evaluated?

i l No. Since the one-time extension should not cause any adverse effects on the snubbers' capability to restrain

! piping systems and components, a new or different kind l of accident from the accidents which were previously l evaluated will not occur. The snubbers should be i available to perform their intended function during the requested extension period.

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l ATTACHMENT 4 NO SIGNIFICANT HAZARDS CONSIDERATION EVALUATION

3. Involve a significant reduction in a margin of safety?

No. The margin of safety will not be significantly reduced by this amendment request because the snubbers and the systems supported by the snubbers should be 1 available to perform their intended function during the I requested extension period. In addition, the review of functional tests which are discussed in the amendment request concluded that no adverse effects should occur as a result of the one-time extension.

I Duke has concluded, based on the above information, that ,

there are no significant hazards involved in this amendment i request. i i

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1 ENVIRONMENTAL IMPACT ANALYSIS Pursuant to 10 CFR 51.22 (b), an evaluation of the proposed amendment has been performed to determine whether or not it meets the criteria for categorical exclusion set forth in 10 CFR 51.22 (c) 9 of the regulations. The proposed amendment does not involve:

1) A significant hazards consideration.

This conclusion is supported by the determination of no ,

significant hazards.

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2) A significant change in the types or significant increase in the amounts of any effluents that may be released offsite.

This amendment will not change the types or amounts of any effluents that may be released offsite.

3) A significant increase in the individual or cumulative occupational radiation exposure.

This amendment will not increase the individual or cumulative occupational radiation exposure.

In summary, this amendment request meets the criteria set forth in 10 CFR 51.22 (c) 9 of the regulations for categorical exclusion from an environmental impact statement.

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