ML20151A536

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Model Tech Specs 3.6.1 & 4.6.1 for Hydraulic Snubbers
ML20151A536
Person / Time
Site: Yankee Rowe
Issue date: 06/30/1975
From:
Office of Nuclear Reactor Regulation
To:
Shared Package
ML20151A535 List:
References
NUDOCS 8011030763
Download: ML20151A536 (5)
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LIMITING CONDITIO." FOR OPERATION SURVEILLECE REQUIRDENT 3.6.I Hydraulie Snubbers' 4.6.I Hydraulic Snubbers .~
1. During all modes of. operation The-following surveillance requiremen except Cold Shutdown and Refuci, apply to'all hydraulic snubbers excep-all hydraulic snubbers shall be , those listed'in~3.6.I.2.

operabic except as noted in .

3.6.I.2 through 3.6.I.5 below. 1. All hydraulic snubbcrs whose scal; material has been dctonstrated by

2. The hydraulic snubbers listed operating.cxperience, l'cb testing-in Tabic 3.6.I are not required

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or analysis to be cc:patible to protect the. primary coolant with the operating cnvironecnt systen or any other safety shall be visually it.spected to related system or component . verify their operability in and are therefore exempt from accordance'with the following these specifications. schedule:

-3. From and after thc.'tino that Number of Snubbers Next Required i a hydraulic snubber is determined Found Inoperable Inspection l

to be inoperabic, continued During Inspection Interval l reactor operation is per=issible or-During Inspection i only during the succeeding 72 Interval:

j hours unless the snubber is sooncr- .

made operabic. 0 18 nor.ths 1 250 31 l -

12 conths + 25',

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4. If th'c requirencnts of 3.6.I.1 2 6 conths 7 25',

and 3.6.I.3 cannot be met, an .

3,4 124 days -+?%,

. orderly shutdown shall be initiated 5,6,7 62 dcys 7c '

and the reactor shall be in a ~

>8 31 days T 2 5'.,

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cold shutdown condition within 36, hours. The required insp e i:n intervcil shall not bc lengtc. ned uore than

5. If a hydraulic snubber is deternined one step at a tinc.

to be inoperabic while'the reactor is in the, shutdown or refuel code, Snubbers may be c:.t.;0rized in the snubber shall be cade operable two groups , "accesi .:, c or prior to reactor startup. " inaccessible" base, on their accessibility fop :.:.spection I

during reactor oper..:icn.

. These two groups ta:' be inspected.

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independently according to the l '. above schedule.

i 2. All hydraulic snub',.ers whose seal I materials have not been i deiaonstrated to bc :capatible with the operatik; nreir:n=ent shall be visually.1 :spegted for operability' eve y 31 days.

8011030'7

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. LIN1k'1SO CONDTTION 'FOR 'OPERAT.10N SURVEILIANCE RE00fREMEhT ,

. ,4e60I: Hydraulic" Snubbers (cont'd)o

3. The;initialcinspection'shall.be performed within 6 conths from the ,

date of issuance of these specifi-4 cations. For thc1 purpose of entering;;

the schedule-in specification 4.6.I.1, it shall be assumed that -

Lthe facility had been on a 6 r.onth .

linspection. interval. '

4. ~ 0nc.c cach refueling cycle, a repre- li

.sentativo sample of.10 snubbers or.

.approxima'tcly 10%'of the snubbers, I whichever is~1ess, shall bc  ;

functionally l tested forioperability: f; including verification 'of' proper !4 piston movement, 1cck up and biced, l' For each unit and subsce,uent i unit found inoperabic, an addi icnal:

10% or ten' snubbers.sha'.1.bc so '

tested'uatil no acre failures are found' or all units have been tested, i a

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5. Once cach refueling cycle at. least .,

,two representative s ,ub':ers 'fren 1 a relatively severe env rcr.cen:

shall be completely disassembled.  ;

and examined for damage and i abnormal seal degradation. i G

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~ TABLE 3.6.I d'

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New Boston Edison Co.'No. . Location

  • Elevation l 4

S-1-3Q-1 }!ain Steam Line ' A 24'9" S-1-30-2 Main Stcas Line A 24'9"-

S-1-30-3

S-1-30-7 Main Stcan Line D- 24'9" S-1-30-8 Main Stcan Line D 24'9" S-1-10-9 From Stop Valves 28'6" S-1-10-10 ,From Stop Valves 28'6" <

S-1-10-11 To,Stop Valves 39' ,

S-1-20-12 To.Stop Valves 39'

  • S-1-10-13 .To Stop Valves 39'3" S-1-3-14 To Stop_ Valves 24'9" S-1-3-15 To Stop Valves 39'3" S-1-10-16 To Stop Valvcs- 24'9"

,' S-1-3-17 Stcan By-Pass 40'3" S-1-3-IS- Stcan By-Pass 40'3" S-1-3-19 Stcan By-Pass . 38'7"-

S-1-10-20 '

B Train Occr 2nd Point -

21' S-1-10-21 D Train Over 2nd' Point. 21' S-1-10-22 . B Train Over 2nd Poin: 21' S-1-10-23 B Train Over 2nd' Point 21' S-1-10-24 B Train Over 2nd Point 21' '

A Train Over 2nd Pdint'-

S-1-10-25 21' S-1-10-26 A Train Over 2nd Point 21' S-1-10-27 A Train Cver 2nd Poin 21' S-1-10-2S A Train Over 2nd Point 21' S-1-10-29 A Train over 1st Point ,21' .

S-1-3-3S Air Ejectors. 34' .

S-1-3-39 Air Ejectors 2S' S-1-3-40 Air Ejectors 34' S-1-3-41 Air Ejectors

  • 34' S-1-3-42 Air Ejectors 35' O

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  • BASES:

>13.6.Iand'4.6!I *

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llydraulic Snubbers '

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Snubbers are designed to prevent unrest' rained pipe' action under dynamic' loads as

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might occur during an carthqua,ke'or severe transient, while. allowing nor:al-thermal motion during startup and . shutdown. The consequence of an inoperabic. snubber is. .i an increase in' the probability of structural damage to piping as a .rcsult of a seismic l or other event initiating dynamic loads. It is therefore required that all. hydraulic snubbtrs required.to protect the pri ary. coolant system or any other safety system or component be operabic during reactor operation. l L

Because the snubber protection is required only'during relitively low probchility l cvents, 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 er replaccrents. In case a j 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.rcach a cold shutdown ecndition .c will permit. an orderly shutdown consistent with standard operating procedurcs.  !~

Since plant startup should.not con =ence with knowingly" defective safety rciated  ;

equipment, Specification 3'.6.I.S prohibits s.tartup with incierabic snubbers.  ;

All safety related hydraulic snubbers are visually inspected for overall integrity and operability. The inspection.will include verification of. proper' orient: tion, adequate' hydraulic fluid 1cyc1 and proper attachment of snubber to piping and structures. ,

The inspection frequency is based upon naintaining a constant icycl of . snubber protection. Thus the required inspection' interval varies inversely with th: observed snubber failures. The number of inoperabic snubbers found during a required inspecticn determines the tino interval for the next required inspection. Inspection 8 perfcraed' before that interval has clapsed nay be used as a new reference point to dr;crcino the next inspoetion. However, the results of such cr.rly inspections pericrc.;d'before the original required time interval has clapsed (nominal tine less 25L) may not bc used to lengthen the required inspection interynl. Any inspection whos~e results t, require a shorter inspection interval will override the previous schedule.

Experience at operating facilitics has shewn tht.t the required surveillance program

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should assure an acceptable Icyc1 of snubber porformance provided that the scal.

materials are compatibic with the operating environment.

Snubbers containing seal material which has not been demonstrated by operating  :

experience, lab tests or analysis to be compatible with the operating environment should be inspected more frequently (cycry onth) until catorial compatability

is confirmed or an appropriate changeout is completed.

Examination of defective snubbers at-reactor faci 11 tics and material tests performed at several laboratorie s (Reference 1) has shown that millabic gum polytrothanc ,

deteriorates rapidly under the temperature and noisture conditions present in many snubber locations. Although colded polyurethane exhibits greater resistance to those conditions, it also cay be unsuitabic for application in the higner temperature environments. Data are not currently available to precisely deilne an upper temperature limit for the nolded polyurethane. Lab tests and in-plant experience indicate that seal catorials are available, primarily ethylene propy.lene l

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BASESJ 3.6.I and 4.6.I - . ,

i Hydraulic Snubbers (cont'd) componnds, which should give satisfactory performance .,4e.r the most severe conditions expected in reactor installations.

To further increase the assurance of snubber relinkiilty, functional tests shoul.'

These tests wi11' include stroking of the be perforced once cach refueling cyc1 t.

snubbers to verify proper pistr. cove cat, lock-up and biced. Ten percent or ten. snubbers, whichever is less, represents an adequate sample l'or such tests. ,

Observed failurcs on these sampics should require testing of ad? tional ur.its.

Snubbers in high radiation areas or those especially difficult to recove need not be sc1ceted for functional tests provided operability was previously verified.

To complenent the visual exter.a1 inspections, disassembly and internal ex;mination The for component damage and abnorail seal degradation should be performed.

c'xamination of two units, each refueling cycle, selected from relative.y severe enviro..ments .should adeq2ately serve this purpose. Any observed wear, breakdown or deterioration will provide a basis for additicaal inspections.

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-(1) Report H. R. Erickson, Bergen Paterson to K. R. Coller, NRC, October 7, 1974

Subject:

Mydraulic Shock Sway Arrestors IS1b a'

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