ML19319A666
| ML19319A666 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 12/18/1975 |
| From: | Purple R Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML19319A665 | List: |
| References | |
| NUDOCS 7911210605 | |
| Download: ML19319A666 (5) | |
Text
LI!41TIUG CONDITIC.1 FOR OPERM'C'(
SURVEllIR:CE nrQUIRE!5t;T
-3s6;I 1:ydraulic SnuSbers 4.6.I Ilydraulic Snubber:
1.
During all modes of operation The following surveillance requiremen except Cold Shutdown.and Refuel, apply to all hydraulic snubbers liste al' hydraulic snubbers listed in in Tabic 3.6.1.
Tabic 3.6.1 shall be opernbic except as noted in 3.6.I.2 through 1.
All hydraulic sn bbers whose seal 3.6.I.4 below.
material has been demonstrated by 2.
From and after the tire that pcrating experience, lab testing a hydraulic snubber is deternined or analysi.; to be conpatibic to be inoperabic, continued with the operating env,ironnent reactor operation is permissibic shall be visually inspected.
Tai only during the succeeding 72 inspection shall include, but not hours unless the snubber is sconcg necessarily lim ted to, inspectic made operabic.
of the hydraulic fluid reservoir, fluid connections, and linkage 3.
If the requirements of 3.6.I.1 connections to the piping and and 3.6.I.2 cannot be met, an anchor to verify snubber cperabi:
orderly shutdown shall be initiated in accordance with the folicwi:n; and the reactor shall be in a s ch edu l e.'
cold shutdo.n condition within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />.
Number of Snubbers Next Required Found Inoperable..
Inspection 4.
If a hydre.ulic snubber is determined During Inspection Interval to bc inoperabic while the reactor r D;n ing Inspection is in the shut down or refuel noJc, Interval the snubber shall be cade operable 0
18 months.125l prior to reactor startup.
1 12 conths 4 2R 2
6 months 1 75; 5.
Snubbers nav be added to safety related sys'tems withcut prior 3,4 124 d::ys 1 2F License Amend = cat to Tabic 3.6.3 5,6,7 62 days
+ 21
>8 31 dars
+ 25' provided t hat safety evaluatiens,
documentation and reporting are provided in accordance with 10 The required inspection interra.
CFR 50.59 and that a rcrision to shal).not be lengthened more the Table 3.6.1 is included with a one step at a time, subsequent License Amendmant request.
Snubbers may be categorized in two groups, " accessible" or
" inaccessible" based on their accessibility for inspection during reactor operation.
These two groups may be insr.:et independen iy according to the above scheuule.
2.
All hydraulic snubbers uhese sc materials are other than ethyle propylene or other caterial tr.r has been denonstrated to bc compatibic with the operating environment shall be visually inspected for operabili ty every 7 d'11T10 60f
LIi1ITI!;G' CO.NDITICM FO'l OPERATION SURYF.1LL*d:CE '*QUIREMEhT
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4.6.I liydraulic Snubbers (cont'd)
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3.
The initial inspection shall be perforced within 6 cenths from th date of issuance of these specifi-cations. For the por ose of catcr the schedule in Specification 4.6.I.1',
it shall be asst =cd thet the facilitiy had been on a 6 cont' inspection interval.
4.
Once cach refueling cycle, a repr sentative sampic of 10. snubbers o.
approximately 10*. of the snubbers whichever is Icss,. shall be functionally tested Tor operabili including verifiention of proper piston novement, lock up ant' bice For each unit and subsequent unit found inoperabic, an additi".:
10" or ten snubbers shall be so tested until no tore failures are found or all t; nits have been tes*
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3.6.1 and 4.'6.1 Hydraulic Snubbers
~ Snubbers are designed to prevent unrestrained pipe motion under dynamic loads as eight occur during an carthqi.take or severe transient, while allowing normal thermal motion during startup.and shutdown.
The ccusequence of an in6perable snubber is cn increuse in the probability of structural damage to piping as a result of a scismic cr other event initiating dynamic loads.
It is therefore required that all hydraulic
-snubbers required to protect the primary coolant system or any other safety system cr component be operabic during reactor operation.
Because the snubber protection.s required only during relatively low probability i
cysnts, a p3riod 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 replaconents.
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 permit an orderly shutdovm consistent with standard operating procedures.
RSince plant startup should not commence with knowingly defective safety related equip.r.ent, Specification 3.6.1.4 prohibits startup uith inoperabic snubbers.
All safety reinted hydraulic snubbers are visually inspected for overall inter.rity end operability.
The inspection will include verification of proper orientation, adequate hydraluic fluid Icvel and proper attachment of snubber to piping and structures.
Tha inspection frequency is based upon naintaining a constant 1cyc1 of snubber protection.
Thus the required inspection interval varies inversely with the obser/cd snubber failures.
The nunber of inoperabic snubbers found during a required inspection deternines tho' tine interval for the next required inspection.
Inspections performed befor's that interval has elapsed may be used as a new reference point to determine the next inspection.
the original required time interval has elapsed (ncminal time Icss 25.) nay not b used to lengthen the required inspection interval.
Any inspection whose results 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 level of snubber performance provided that the seal materials are compatibic with the operating environment.
Snubbers containing seal material which has not been danonstrated by operating experienec, lab tests or analysis to be c,ompatibic with the operating environment shculd be inspected more frequently (every month) until material compatibility is confirmed or an appropriate changeout is completed.
Examination of defective snubbers at reactor'facilitics and material tests performed at stveral-laboratorios (Reference 1) has shown that nillable gum polyurethane dateriorates rapidly under the temperature and moisture conditiens present in many snubber locations.
Although molded polyurethane exhibits greater resistence
- ti these conditions, it also may be unsuitable for application in the higher
.t;;perature environments.
Data are not currently available to precisely defino an' upper temperature limit for the molded'polyurethanc.
Lab tests and in-plant cxp;rience. indicate that seal ~ materials are availabic, primarily othylene propylene ISla 4
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'3.6.I and 4.6.I f
!!ydraulic Snubbers '(cont'd)-
.'co ipounds Which should give satisfactory performa'nce under the cost severe conditions expected in reactor installations.
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To further increase the assurance of snubber reliability,, functional tests should be perfor:ned once cach refuelin;; cycle.
These tests will include stroking of the s nubbers to verify proper piston move. ment, lock-up and b ced.
Ten percent or, t en snubbers, whichever is less, represents an adequate {veple for such tests.
Observed fr.ilures on these sampics should require.testin4 of ad'ditional units.
'lhose snub *ocrs designated in Tabic 3.6.1 as being in higil radiation areas' oi-e specially. difficult to rer.pyc need not be sc1ceted for functional tests provided operobility was previously verified.
Sf.-
41)
Report II. R. !irickson, Bergen Prtcrson to K. -R. Coller NRC, October 7,1974
Subject:
- llydraulic' Shock Ss,ay _ Arrestors
- 4..
,7 Tabic 3.6.1
(
c SAFETY RELATED iiYDRAULIC SNU3BERS
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Snubber No.
Location
-Elevation Snubber in Iligh Snubbers Snubbers Snubbers naux'tien Area Especially Inaccessible Accessible Dt in Shutdown Difficult to During Normal During Nor:
Reaeve Operation Operation x
1 Main Steam Line 953' x
2 Main Steam Line 950' x
J 3
Rf!R 964' 4
Iti!R 964' ctc.
Recirculatory 922' x
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