ML20148K134

Revised Model Tech Specs 3.6.1 & 4.6.1 Re Hydraulic Snubbers

ML20148K134
Person / Time
Site:	Yankee Rowe
Issue date:	12/18/1975
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20148K132	List: ML20148K128 ML20148K134
References
NUDOCS 8012020724
Download: ML20148K134 (5)

Text

'masw,w,m,-nnmmerv. .v am m an.us..,..a wr~rrrrc-~mn 3,6.I h'draulic Snubbers 4.6.I  !!yd r. ~ic Snubbers

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1. During all modes of operation The follcwing surveillance requirem

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cxcept Cold Shutdown.and Refuel, ' apply to all hydraulic snubbers list:

. all hydraulic snubbers listed in in Tabic 3.6.',

Tabic 3.6.1 shall be upcrabic cxcept as noted in 3.6.I.2 through -

3.6,I.4 below. 1. All hydraula. e snubbers whose sea;.

material has been d.:monstrated .;

2. 'Fr6 r and after the tire that pperating ' experience, lab testi:..

a hydraulic sunbber is determined pr nalysis to be cccpatible to be inoperabic, continued 'i'ith the. operating ent,ironment reactor operation is permissibic ghallbevisuallyinspecf.cd. Th only during the succeeding 72 gnspectionsha)) , include , but no t

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hours unicss t.ne snubber is soonc:

made operable, of the hydraulic fluid reservoir, fluid connections, and linkar,c 3, i f the require.nents of 3.6.1. j connections to the piping and and 3. 6.1. ca nno t b e t:e t , an anchor to verify. snubber cpe:, i o rd e r]'v shutdown shall be initiated in accord:'nt o wit h the fc1)o.. :.g and the reactor shall be in a s ch ed u l e .'

cold shutdmen condition within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />. Nu:aber of Snubters Next Hequirva round )noperabic. Inspection

4. If a hydraulic snubber is determined l>uring 1:spection Interval to be inoperab} c chile the rer.ctor '

r During Inspection is.jn the shuidcun or refue) uode, Interval

the snubber shall be nade opernb'e prior.16.reacto: Startun. '

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12 tenths * '" '

5. Snubbers nav be "dded to ,afety 2 6 no n t h ; i ?.~-

rc)ated sys'ter.:s wi heut ).rior 3,4 ): .i dcys 1E License Amenth.cnt t'o 'labic 3.6.1 5 , 6 , ~/ 62 days i 25 provided that safety evaluations, fS 31 days 1 2 Ec documentation and reporting are . . -

provided in accordance eith 30 The required inspection inteca CFR 50.59 and that a revision to shall not be lengthened more ti .

Tabic 3.6.1 i's inc}uded with a one st'ep at a tir.o.

subsequent 1.icense Amendment request. Snubbers uay be categori:cd in tWo groups , "aCCes 5i ble" c1

" inaccessible" based on thei:

i accessibility for inspection l during reactor operation.

l These two groups nr.y be inspect l independently according to the above schedule.

l 2. All hydraulic snubbers uhese sc l materials are other th:.n ethylc l ,

prc, lene or other naterial t r. ,

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has , een demonstrated to bc l compatible with the e y ratinL environment shall be visually inspected for operability everf 31 days.

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,', . . 4,6.I liyd r.a".'-_i_c. Snua'a crs (co~n t ' d) -

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,3. The initial inspection shall bc perforced within 6 months from th';

date of issuance of these specifi-

. cations. For.the purpose of enterl

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the schedule in Specification 4.6.I.1, it shall be assuned that the facility had been on a 6 mont.

inspe c t' ion ,in t erv al .

4. On\ ce cach refueling cycle, a reprc sqntative sampic of 10 snnbbers cr a}iproxir::t ely 10% of the snubbers y

, ultichever is Icss ,_ shall be fubetionally tested Tor operabili:

including verification of proper pis t on' mover:en t , lock up and - iccJ For cach ur.it and subsequent unit found inopciabic, nn adcli? ) c:

104 or ten snu'abcrs sh:111 be so tested until no it. ore failures are found or all units have been test:

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BASES:

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5.6.I'and 4.6.1 . .

Hydraulic Snubbers

• Snubbers are designed to prevent unrestrained pipe motion under dynanic loads as

'might occur during an carthqyah n 'severo transient, while allowin; rormal thornal motion during startup and shur'.wn. The consequence of an inoperabic snubber is an incr..ase in the probability of Mtructural damage to piping as a rcsult of a seismic or other event initiating dynamic loads. It is therefore required that all hydraulic snubbers required to protect the pcinary coolant system or any other safety systen or component be operabic during reactor operation. ,

Because the snubber protection is required only during relatively low probability events, a period of 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> is allowed for repairs or replacements. In case a shutdown is required, the allowance of 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> to reach a cold shutdown condition will pcrait an orderly shutdown consistent with standard operating procedures.

Since plant startup should not commence with kncuingly defective safety related equipment, Specification 3.6.1.4 prohibits startup with inoperabic snubbers'.

All safety related hydranlic snubbers are visually inspNted for ovem11 integrity and operability. The inspection will include verification of proper orientation, adequate hydraluic fluid Icvel and proper attacMen of snubbar to piping and structures.

The inspection frequency is based upon naintaining a constant Jovc1 of s ubber protection.

Thus the required inspection interval varles inversely with the observed snubber failures. 'ihe number of inoperable snubbers found during a required inspection determines the time interval for the next required inspection. Inspoeticas perforned before that interval has clapsed nay be used.as a new referenec point to determine t'he next inspection. H oucve r, the original required time interval has elapsed (nninal ti:10the less results 256 nayofnot such be early inspe used to lengthen the required inspection interval. ' Any inspection whose resu1~

require a shorter inspection interval will override the previous schedule.

Experience at operating facilitics has shown that the required surveillance program should assure an acceptable Jevel of snubber performance provided that the seal materials are compatible with the operating environment.

Snubbers containing seal material which has not been de.onstrated by operating experience, Jab tests or analysis to be compatible with the operating environtent should be inspected more frequently (every month) until material compatibility is confirmed or an appropriate changcout is completed.

Exar..ination of defective snubbers at reactor facilities and material tests performed at several laboratories (Referance i) has shown that millabic gua polvurethane deteriorates rapidly under the temperature and noisture conditions present in many snubber locations.

Although molded polyurethane exhibits gr : _er resistence to these conditions, it temperature environments. also nay be unsuitable for application in the higher Data are not currently availabic to precisely define an up" 7 temperature limit for the nolded po'yurethane. Lab tests and in-plant expermaco indicate that seal materials are available, prinarily othylene propylene 151a

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- , BASES:

'3.6.I and 4.6'.I . . .

.. liydraulic Snubbers (cont'd) " ,

compoun'ds, which should give satisfactory performance under the most. severo conditions expected in reactor installations. 3 l

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To further increase the assurance of snubber reliability,, functional tests should 1 be performed once cach refueling cycle. These tests wil!1 include stroking of the s nubbers to verify proper piston covement, lock-upandbgced. Ten percent or, ~

t en snubbers, whichever is less, represents an adequate j,a:nple for such tests.

Observed failures on these sa::ples shou]d require .testin Those snubbers desigr.ated-in Tabic 3.6.1 as beinp. inradiation higi)' ofareas additional oi- up,its.

e specially difficult to reuove need not be selected for functional tests provided cperability was previously verified.

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(1) Report 11. R. Erickson, Bergen Paterson 'to K. P,. Go!1er, NRC, Octobur 7,197.1

Subject:

ilydraulic Shock Sway Arrestors

t Table 3.6.1- .

SAFETY RELATED iiYDi'AULIC SNUP.BERS

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e Snubber in iiigh Snubbers Snubbers Snubbers

. -ation Elevation Inaccessible Accessibic P.adiatic a Area Especially Durinj: Shutdown Difficult to During Nor::.21 During No:a.

Renere Operation Operation' 1 Main Steam Linc 953' - x

<< 2 Main Steam Line 950' x 964' v.

3 RIIR 4 RilR 964' ctc. Recirculatory 922' x

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