ML20037B358
| ML20037B358 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 12/17/1975 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20037B357 | List: |
| References | |
| NUDOCS 8009150630 | |
| Download: ML20037B358 (5) | |
Text
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,o 11h1 TIS CONDITION FOR OPERKi N
' SURVEI LLANCE '...:QUIREMENT-
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13.6.1 Hydraulic Snubbers 4.6.I Hydraulic Snubbers 1.
During all modes of operatien The following surveillance requirements except Cold Shutdoun and, Refuel,.
apply to all hydraulic snubbers liste,d.
- p all hydraulic snubbers listed in -
_in Table'3.6.1.
- d' Table 3.6.1'shall' be operable except as_noted in 3.6.I.2 through All hy' raulic snubbers whose seal d
1.
3.6 I.4 below.
caterial has been demonstrated by operating experience, lab testing 2.
From and after the tire that-a hydraulic snubber is determined or analysis -to be' compatible -
to be inoperable, -continued with the operating environrent reactor. operation is permissible shall be visually. inspected. %is only during the succeeding 72 inspection shall include, but not hours unicss the snubber is sooner necessarily limited to, inspection
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made operable.
of the hydraulic fluid reservoir, fluid connections, and linkage 3.
If the requirements of 3.6.1.1 connections to the piping and anchor 'to verify snubber.operabildt and ' 3.6.I.2 cavot be met, an in accordance with the following orderly shutdown shall be initiated and the rc; etor shall be ina schedule cold shutdown condition within
.Next Required Number of Snutbers 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />.
Found Inoperable' Inspection 4.
II a hydraulic snubber is determined During Inspection Interval r'During Inspection to be inoperable while the reactor
-Interval is in the shutdown or refuel. mode, the snubb'er sL.111 be made operable 0
18 nonths i ?5; prior to reactor startup.
1 12 nonths + 254.,
2 6 months [25%
5 '.
Snubbers cay be added to safety s
3,4 124*deys _ r 250 related systems without prior 1
License Anendment to Table 3.6.;
5,6,7 62' days 2
provided that safety evaluations, 3.S.
31 days y 25%
documentation and reporting'are The required inspert'on. interval.
provided in accordance with 10 shal); w t be len.shened mora than CFR 50.59 and that a revision to Tabic 3.6.1 is included with a one step at a time.
subsequent License Amendment Snubbers r.ay be categoriaed in request.
two groups, " accessible" or
" inaccessible" based on their accessibility for inspection during reactor operation.
Thesc tuo groups nay be inspected independent'ly according to the above schedule.
7 2.
All hydraulic snubbers those seal materials are other than ethyl m propylene or other cateria] th'.
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LIMITI51 COSDITION FOR OPERNI
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SURVEILLUCE JUIPEfENT 4.6.I Hydraulic Snubb rs (cont'd) 3.
The initial inspection shall be performed within 6 months frca the date of issuance of these specifi-cations. For the purpose of enterin; the schedule in Specificatior.
4.6.1.1, it shall be assumed that the facility had been on a 6 month inspection interval.
'ts 4.
Once cach refueling cycle, a repre-sentative sample of 10 snubbers or approximately 10% of the snubbers, whichever is less, shall be functionally tested for operability including verification of proper pisten rovement, lock up and bleed.
For each unit and subsequent unit found inoperable, ar additionn) 10', or ten snubbers shal: be so tested until no r;re failures are found or all units have been tested.
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BASES: _
3.6.'I and 4.6.I Hydraulic Snubbers
-Snubbers are designed to prevent unrestrained pipe notion under.dynnnic -loads as
" y nigh occur during an earthquake or severe transient _,_while clicwing nomal thernal:
motion during startup cnd shutdoun.
The consequence of aniinoperabic srnbber'is -
'1 an increase in the probability of st=ctural d::'.gc to piping as a result.of a scistic or other event initiating dyn:cnic Ictds.
It'is therefore rcquired th :Lcal hydraulic
' snubbers required to protect the prinary ecolcnt systen or any other scfety system-or?cc:penent be operable during reactor operatica.
Because the snubber protection is required only-during relatively lou probability events, a period of 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />s-is allowed for repairs or replacencnts.
In casc a shutdoun'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 shutdounicendition.
will perait an orderly shutdown consistent with standard opercting procedures.
Since plant startup should not cc=ence with knc. ingly defective safcty related equipacnt, Specification 3.6.I.4 prohibits stcrtup with inopert bic snubbers.
All-safety related hydraulic snubbers nre visually inspected for overall. integrity '
and operability.
The inspection vill include verification of: proper orientation,_
adequate' hydraulic fluid-level.and proper attachnent of snubber to piping and structures.
The inspection frequcncy is based upon r.aintaining a constant icyc1_of snubber protection.
Thus the required inspection interv d varies inversely with'the observed snubber fcilures.
The nuubt of hoperabic uubbers found.during a required inspectica determines the tire interval for the next require,d inspecticn.
Inspectiou perfom ed' before that intersal has elapsed nay be used as a new refercnce point to deter :ine
- the next ' inspection.
However, the.results of such enr)y inopections perfomed.before the criginal required time interval has clapsed (noninal tine less 254) ncy'nct'bc.
used to lengthen the required inspection interynl. Any inspection whose results require a shorter inspection interval vill override the prcvicus schedulo.
Experience at operating fccilitics has shown that the required surveillanec progra-should assure an acceptable level of snubber perfornance provided that the seal materials are compatibic with the operating environment.
Snubbers centcining seal nutcrial thich has not bcea demonstrated by operating experience, Inb tests or cnalysis to be corpatirle with the operating envircn.ent should be inspected nore frequently (ev3ry =onth) until caterial eo:patibility is confined or an appropriate chanycut is cc:pleted.
Exanination of defective snubbers at : A tor faci]itics and natcrial tests perforacd at several laboratories (Reference 1) has shown that nillabic gum polyurethr.no deteriorates _ rapidly under the temperature and noisture conditions present in nany snubber locations.
Althcugh nolded polyurethanc exhibits greater resistance to these conditions, it also rcy be unsuitable for application in the higher tenperature envirorcents.
Dcta are not currently avsilable to precisely define a uppr tercjeratun limit fer the meided polyureth..c.
- .:. te m a d in-;a.r.:
experienn indicate :Fnt seal -raterisls are avai nble, pri=rily' c9yletie' 7 rep.lene 4
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BASES:
-3.6.I and 4.6.I llydraulic Snubbers (cont'd) compounds, which should give satisfactory performance under the most severe conditions
. expected in reactor installations.
To further increase the assurance of snubber reliability, functional tests should be performed once each refueling cycle.
These tests will incluue stroking of the 3
s nubbert to verify proper piston movenent, lock-up cnd bleed. Ten percent or'
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ten snubbers, uhichever is less, represents an_ adequate sample for such tests.
Observed failures on these samples should require. testing of additional units.
Those snubbers designated in Table 3.6.1 as being in high radiation areas or e specially difficult to remove need not be selected for functional tests provided operability scas previously verified.
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