ML20043A366

Proposed Tech Specs Re Surveillance Requirements for Visual Insp of Snubbers

ML20043A366
Person / Time
Site:	Limerick
Issue date:	05/16/1990
From:	PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:
Shared Package
ML20043A363	List: ML20043A362 ML20043A366
References
NUDOCS 9005210259
Download: ML20043A366 (7)

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-s ,t ATTACHMENT ~1-a i

.i' LIMERICK GENERATING STATION.

' UNIT 1- Ti e--t DOCKET.N0.-

50-3523 .

LICENSE N0. NPF-39 t

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" TECHNICAL SPECIFICATIONS ' CHANGE REQUEST- t

.NO. 90-11 .. ,;

=i "One-Time Extension of the' Visual [

' Inspection Period for Snubbers"-

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Supporting.Information for Change;- 4:lpages- '

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i 9005210259 900516 gDR ADOCK 05000352 9, PDC I i o

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_ Docket No. 50-353

,, License No. NPF-85 REQUESTED CHANGE Philadelphia Electric' Company (PECo), Licensee under Facility Operating License NPF-39 for Limerick Generating Station.(LGS), Unit 1, requests-that the Technical Specifications (TS) contained in Appendix-A to the Operating License be amended as proposed herein to allow a one-time extension of.the visual inspection period for' snubbers. The proposed change is indicated with~a vertical bar in the margin of page 3/4 7-12, and is contained in Attachment 2.. The current reduced visual inspection period for the affected snubbers, including the:25% grace period,. expires on July-14, 1990. This proposed change would extend the inspection period-to the:end of the upcoming refueling outage, currently scheduled to begin in September, 1990.  !

Accordingly, we request your prompt attention to this Change Request.and that the changes proposed herein be effective upon issuance-of-the Amendment, j This Change Request provides a discussion of the proposed TS change, a-safety assessment of the proposed change, information supporting a finding of No Significant  !

Hazards Consideration, and'information supporting an Environmental Assessment.

DISCUSSION OF CHANGE i

This request for a one-time increase of the visual inspection period for j snubbers from the current TS required reduced period of 12 months plus 25%_(i.e., 15 i months)totheendofthenextUnit1refuelingoutage-(i.e.,atotal_periodof ,

approximately 18 months) involves <three (3) mechanical snubbers (snubber nos.:DCA-  :

185-E01-H2, -H3, and - H6)-attached to a 2 inch drain line on the "B" train of the 'l Reactor Recirculation system suction piping. .In April,=1989 -during the second' LGS- '

Unit 1 refueling outage.-the required visual inspection'of. snubbers was performed in  !

accordance with TS section 4.7.4b. During this inspection, mechanical snubber no.

DCA-185-El-H2 (size PSA-1/4) was identified as having an_ alignment problem, and was  :

removed for functional testing and replaced with;a new-snubber. 'The results of_the functional test and tear-down inspection indicated that it was locked-up rigid with {

rust and corrosion inside the snubber housing, torque carrier, capstan spring,. and  !

on other internal components (there had been no' indications' of external corrosion). i Snubber DCA-185-El-H2 was then classified as a visual inspection failure and, in -

accordance with TS section 4.7.4b, the visual inspection frequency for the: snubbers .

on the associated system was reduced from 18 months + 25% to 12 months + 25%. '

In order to ensure the operability of the asseciated DCA-185-El Drain Piping at that time, a re-inspection and evaluation of the remaining snubbers-(DCA-185-El-H3 and -H6) were performed. These snubbers had previously met the: visual ' inspection i acceptance criteria. The results of the snubber inspection showed that DCA-185-El-H3 failed a functional test (drag value in compression was 0.5% greater _than allowable '

limit of 2.0%) but had no signs of internal corrosion. Snubber DCA-185-El-H6 passed a hand stroke test and was classified as operable witnaut the need for functional testing.

Snubbers DCA-185-El-H2 and H3 were original plant equipment, and snubber DCA-185-El-H6 had been replaced during the first Unit I refueling outage due to internal corrosion, s

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In this case we determined through visual inspection, that the as-found-

' condition of one snubber (H2) was unacceptable. Subsequent funct.ional testing 1

i revealed'a failure mode (i.e., internal corrosion)_which was unrelated'to the-original. visual-inspection discrepancy (i.e., alignment). Tests and inspections on j '

snubbers H3 and H6 reinforce the conclusion that new information resulting from a y

' visual inspection of these snubbert prior to:the next refueling outage is unlikely l since little information as to r tual snubber functionality was derived from-the past i visual inspections. Furthermore, the' probability that corrosion problems will j initiate and progress to a point where_ snubber performance is unacceptable pr.ior to  ;

the'next refueling outage is low since snubbers H2 and H3 have been replaced with'new -!

snubbersduringthelast(i.e.,second)UnitIrefuelingoutage,andsnubberH6was- :i replaced with a new snubber during the first Unit 1 refueling outage. In addition, there is no anticipated source of corrosion-at the location of these snubbers in the inerted containment during an operating cycle, ,

An evaluation was performed to determine-if the as-found snubber test results would have any adverse affects on the attached piping-or components. The results.of j this evaluation indicated that the piping thermal expansion stresses.for all- y components except one elbow were' greater than the standard allowable' thermal stress  ;

limit but below the ASME code allowables for. consideration of plastic hinge i

' formation. The consequences of these results are that the potential may have: existed for hinge formation at this elbow. Because of'this potential. visual and dye penetrant examinations were performed on the elbow and' piping in the areas of high calculated stress. The results of the non-destructive examination-revealed no rejectable indications or other adverse conditions such-as yielding, bulging, or hinge formation. This evaluation supports this Change-Request because:the.results demonstrate the conservatism associated with-the the snubber and piping system assessment. ] ,

l; SAFETY ASSESSMENT '

The consequences of this proposed change with respect to the piping and- -[

components that the affected snubbers are protecting, and the impact on postulated accidents from extending the inspection interval from 15 months to the end of the '

next refueling outage (approximately 18 months) were evaluated. The following 1 postulated accidents were considered in this evaluation as producing loads that could affect the subject snubbers. ~

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Seismic events Safety Relief Valve Discharge  !

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. Loss of Coolant Induced Loads Postulating the worst case condition, that is, lock-up of the three affected snubbers, could result in plastic hinge formation at the drain line elbow described above. Failure of this elbow, which is located at the connection'of the drain line t to the Reactor Recirculation suction piping downstream of the suction isolation valve, is highly unlikely since additional plastic deformation'would probably occur prior to failure. Nevertheless, assuming that the drain line did fail at this elbow, the resulting leakage from the reactor coolant system would be isolable, and would be recognized by plant operators via plant parameters and alarms such as drywell- l 1

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4 pressure-and temperature, drywell unit cooler condensate flow, or flow from the drywell floor' drain collection tank. Accordingly, this postulated transient would be, within analyzed conditions Land could be mitigated by the plant _ operators in-accordance with existing procedures. In addition,-' assuming worst case drain line

- pipe loading conditions due to lock-up of the affected snubbers, we have concluded -

that the associated Reactor RecircOation suction pipe and -isolation valve would not be adversely affected.

.We have evaluated this proposed change with respect to the criteria in 10 CFR 50.59 and have concluded that an unreviewed safety question.is involved since j

t extending lthe. reduced visual inspection period for the affected snubbers.may increase the incidence of undetected, snubber failures and, as discussed below, reduce the '

margin of safety as described.in-the TS Basis. This reduction of-the margin of-safety is,-however, not significant.

The margin.of safety as described in TS Basis 3/4.7.4 will be reduced. The TS' .;

Basis indicates that the reliability of equipment performance with regar_d to'the use-

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of snubbers is based, in part, on visual inspections, functional testing, and service life. .Since previous snubber testing results' required'a reduction of the. inspection '

interval in accordance with TS, then we conclude that-the margin of: safety is maintained only if the inspection. intervals are reduced. Therefore, any testing intervals greater than those specified'in the.TS for'given-visual inspection failure rates could cause a reduction-in a' margin of safety as currently described in the TS Basis. Since the requested extension .is limited to three-snubbers attached to one segment of inaccessible 2 inch diameter: piping,Jthe probability that a one time t extension of the visual inspection. period.for these.. snubbers will significantly-increase the incidence of undetected snubber failures is low.'.Moreover, even1though there may be small' reductions in localized margin of safety because of undetected snubber failures, the overall reduction in the margin of safety will not be-significant.

Information Supporting a Finding of No Significant Hazards Consideration l We have concluded that the proposed change to the LGS' Unit l'TS to allow a one-time extension of the visual inspection period for snubbers does not constitute a Significant Hazards Consideration. In support of this determination, an evaluation of each of the three standards set forth in 10 CFR 50.92 is provided below.

(1) The proposed change does not involve a significant increase in the i probability or consequences of an acci, dent previously evaluated.

Lengthening the inspection interval for snubbers will not change the i probability of accidents since-snubbers do not cause-accidents. ,

Additionally, even though there may be slight reductions in local' safety ~1 margins,.the overall effects will be that the consequences of accidents previously evaluated will be unchanged.

(2) The proposed change does not create the possibility of a new or different kind of accident from any accident previously evaluated.

The proposed change only concerns extending inspection period for certain snubbers. These snubbers, whether operable or inoperable, do not change 1

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M plant operation and therefore the proposed change willtnot create the possibility of a new or,different kind.of accident from any accidentc

previously evaluated.-

-(3) The proposed change'does not~ involve a-significant-reduction in-a margin

- of safety.: .

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Lengthening-the' inspection intervat increases the chance that_ inoperable.

. snubbers will;gol undetected for a longer period of time.D This could result in a system that is"not; configured as-designedL(with, regard to-

.dynamicorrigid' restraints)gand..theremay!be"localincreasestinpiping' and support" loads / stresses.-

However' considering=the fact that prior:to startup-f'or'the~ current nit-1:

operating'cyclei twoLof the.affected snubbers were. replaced with operable; a isnubbers and'the third affected snubber was' tested and verifiedtoperable.

'theretis:a high' confidence-level that these three snubbersiwill not adversely affect Recirculation systemLoperability. Therefore'. the .j proposed change does not involvera significant reduction in a margin:of;

. safety..

INFORMATION SUPPORTING AN ENVIRONMENTAL ASSESSMENT-

.An environmentaliassessment is not required for,the change proposed.by' thisi-o L Change. Request because' the = requested l change conforms to,thei criteria - for ;" actions- j eligibleJfor! categorical: exclusion'P as:specified in -10 CFR 51'.22(c)(9). Thei requested change ^will' have:no' impact;on the : environment.: :The proposed change does' not involve'a3significant~ hazards consideration as-' discussed in the preceding q section. The proposed changeLdoes-not-involve aLsignificant change:inLthe. types or.ai a significant-increase-in the amounts of:any effluents that'mayfbe released offsite. 4 11n addition, the proposed changeLdoes not involve >a significant increase'in individual:or cumulative occupational radiation exposure.:

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CONCLUSION .;

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The Plant Operations ~ Review Committee and the' Nuclear Review Board haverreviewed this. proposed change'to'the TS and have concluded that'it'does; involve a unreviewed safety question but'does not involve ~a significant hazards consideration.'and will not endanger the health and safety of the public. ,

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-ATTACHMENTc-2 ~ '

LIMERICK' GENERATING -STATION :

l UNIT ul .

DOCKET.NO. 50-352: ,

1 LICENSE-: NO. ' NPF-39 -: n v.; .

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= PROPOSED TECHNICAL SPECIFICATIONS: CHANGE REQUEST;

-NO. 90-11-.1'- ll9 d

List of Attached' Change:Page-.  ;

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.3/4'7-12 >

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• 9.,LANJ SYSTEMS-

, JURVEILLANCE' REQUIREMENTS (Continued) q y

Lf No Inoperable' Snubber of' .. .

.Each Type on..Any System -Subsequent' Visual- -i per Inspection Period: Ins)ection Period *#** . b. 1 0 .13 months + 25%- d"

-1 12 months i 25%.

2 6 months i 25%! o 3.4- 124 days + 15%: 1

. 5,6,~7L 62 days 325%'

8 or more -31 days + 25%' 1 s

ic. . Visual--Inspection Acceptance Criteria-Visual inspectionsEshal1Lv'erify (1)Lthat,there are.no visible indications ofi '

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damageorimpairedOPERABILITY,'(2)Lattachmentstothe.foundationor .

supporting structurelare secure, and (3) fast _eners'for; attachment:.of thet i snubber to the component'andtto the snubbercanchorage are secure. Snubbers = '

.which appear inoperable as a'resultfofsvisual, inspections may be determined:

.0PERABLE.for the purpose;of establishing the'next; visual inspection 1 j

linterval,.providing that: (1):theLcauseofthe'rejectionisclearly... .

established and= remedied for that particularssnubber and for'other snubbers.  ;

-irrespective of type on-that system that may be generically susceptible;- 4 9

and/or'(2) the affected snubber.istfunctionallyctested in the as found'

condition and determined OPERABLE'per Specifications:4.7.4f; Fv those! "

' snubbers common'to more than one system,2the-0PERABILITY ofisuch snubbers- -

. shall: be considered in assessing..the surveillance sch'edulet for rach.of the related systems.-

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d. Transient' Event' inspection  !.

4 An inspection shall be< performed of all snubbers attached to1 sections of; i g systems.that have experienced unexpected, potentially damaging transients, as determined fromia review of operational data orJa: visual . inspection of.

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the. systems, within 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />s-for. accessible systems;and 6 months for  !

P inaccessible systems following'this'determinatione In addition to' satisfying the visual inspection acceptance criteria,Lfreedom-of-motion-of mechanical snubbers shall be> verified.using at least one of the following:

(1) manually induced- snubber' movement; or. (2) evaluation of in-place snubber piston setting;'or (3)' stroking the mechanical snubber through;its full.

range of travel..  :.

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The inspection interval for each type of snubber on a given system shall not:be; ,

lengthened more than one step at a time unless.a' generic > problem has.been

• identified and corrected;-in that event.the inspection interval _may be lengthened' on step the first time and'two steps ~thereafter if no inoperable snubbers of that-type are-found on that system.

1. 'The provisions of Specification 4.0.2 are not applicable.

[ Those surveillances on inaccessible snubbers which must be performed on or before l July 14, 1990 and are required by. Specification 4.7.4.b may be delayed for a-period not to extend beyond the end of the next Unit I refueling outage.

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