ML19319D772
| ML19319D772 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 07/01/1975 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML19319D762 | List: |
| References | |
| NUDOCS 8003250772 | |
| Download: ML19319D772 (5) | |
Text
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,1.IMITfNG CONDITIO" FOR OPE..fION SURVEILLW.c REOUIRDENT 3.6.I Hydraulic Snubbers 4.6.I Hydraulic Snubbers 1.
During all modes of operation The following surveillance requirene 0
except Cold Shutdown and Refuel, apply to'all hydraulic snubbers exec all hydraulic snubbers shall be those listed in 3.6.I.2.
operable except as noted in 3.6.I.2 through 3.6.I.5 below.
1.
All hydraulic snubbcrs whose sea material has been dcconstrated b 2.
The hydraulic snubbers listed operating experience, lab test:.n in Tabic 3.6.I are not required or analysis to be ec:patible to protect the primary coolant with the operatin; cnvironment system or any other safety shall be visually inspected to related system or component verify their operability in and are therefore exe pt from accordance with the following these specifications, schedule:
3.
Frem and after the tine that Numbel of Snubbers Next Required l
a hydraulic snubber is deterained Found Inoperable Inspection j
to be inoperabic, continued During Inspection Interval l
reactor operation is permissible or During Inspection
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only during the succeeding 72 Interval' l
hours unless the snubber is sooner I
made operabic.
0 18 nonths + 250 yy 1
12 sonths + 27; l
4.
If the requirements of 3.6.I.1 2
6conths[2Z and 3.6.I.3 cannot be net, an 3,4 124 days 12n orderly shutdown shall be initiated 5,6,7 62 6ays
-+ 2M and the reactor shall be in a
~>8 31 days
~ 2 3',
cold shutdown cendition within
- 36. hours.
The required idspcc icn intervcil shall not be lengd..ned more th 5.
If a hydraulic snubber is determined one step at a tine, to be inoperable while the reactor is in the shutdown or refuel mode, Snubbers may be c:c.z;arized in the snubber shall be made operable two groups, "accese..i.0" or
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prior to reactor startup.
" inaccessible" basce on their accessibility for.:.nspection during reactor oper.;; ion.
These two groups t v be inspectc independently according to the r
l above schedule.
8 2.
All hydraulic snubbers whose see i.
materials have not '.seen i
demonstrated to be ec patible with the operating envirencent shall be visually inspected j
for operabillty every 31 days.
I 137a I
1 0003 sso ? ? 2 i
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'.1,IM"ITING CONDITION FOR OPERATION SURVEILIANCE REOUIREMENT 4.6.I Hydraulic Snubbers (cont'd) 3.
The initial inspection shall be performed within 6 onths from the date of issuance of these specifi-4 cations.
For the purpose of entering the schedule in Specification 4.6.I.1, it shall be assumed that the facility had been on a 6 month inspection interval.
4.
Once cach refueling cycle, a repre-sentative sampic of 10 snubbers or approximately 10% of the snubbers, whichever is less, shall be functionally tested for operability including verification of proper i
P ston movement, lock up and biced.
For each unit and subsequent unit found inoperabic, an additional lot or ten snubbers sha 1 be so tested until no = ore failures are l
found or all units have been tested.
5.
Once cach refueling cycle at least
,two representative snub'.5crs fron a relatively severe env ror.nent shall be conpletely disassembled and exaained for damage and abnormal seal degraa:ica.
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137b O
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' TABLE 3.6.I ~
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i New Boston Edison Co. No.
Location Elevation S-1-3Q-1 Main Steam Line A 24'9" S-1-30-2 Main Steam Line A 24'9" S-1-30-3
' Main Steam Line B 24'9" S-1-30-4 Main Steam Line B 24'9" S-1-30-5 Main Steam Line C 24'9" S-1-30-6
' Main Steam Line C 24'9" S-1-30-7 Main Stcan Line D 24'9" S-1-30-8 Main Steam 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 Valves 24'9" S-1-3-17 Otrn Py-Pass 40'3" S-1-3-18 Steam By-Pass 40'3" S-1-3-19 Stcan By-Pass 38'7" S-1-10-20 B Train Over 2nd Point 21' S-1-10-21 B Train Over 2nd Point 21' S-1-10-22 B Train Over 2nd Point 21' S-1-10-23 B Train Over 2nd Point 21' S-1-10-24 B Train Over 2nd Point 21' S-1-10-25 A Train Over 2nd P6 int 21' S-1-10-26 A Train Over 2nd Point
21' S-1-10-27 A Train Over 2nd Point 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-25' S-1-3-40 Air Ejectors 34' S-1-3-41 Air Ejectors 34' S-1-3-42 Air Ejectors 35'
- 1 137c a
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-BASES :
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3.6.I and 4.6.I Hydraulic Snubbers 4
Snubbers are designed to prevent unrestrained pipe motion under dynamic loads as might occur during an earthqua.ke or severe transient, while allowing normal thermal motior. during startup and shutdown. The consequence of an inoperabic snubber is an increase in the probability of structural da. age to piping as a result of a seismic or other event initiating dynamic loads.
It is therefore required that all hydraulic snubbers required to protect the prinary coolant system or any other safety system or component be operable during reactor operation.
Becausethesnubberprotectionisrequiredon[yduringrelativelylowprobability 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 er 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 permit an orderly shutdown consistent with standard operating procedures.
Since plant startup should not cor=cace with knowingly defective safety related equipment, Specification 3.6.I.S prohibits startup with inoperabic snubbers.
All safety related hydraulic snubbers are visually inspected for overall inte ;rity and operability.
The inspection will include verification of proper orientation, adequate hydraulic fluid Icvel and proper attach =ent of snubber to piping and structures.
The inspection frequency is bastd upon.aintaining a constant Icyc1 of snubier protection. Thus the required in.spection interval varies inversely with thz observed snubber failures. The number of inoperabic snubbers found during a required inspectica determines the time interval for the next required inspection.
Inspections peric=cd before that interval has el.psed may be used as a new reference point to detemine the next inspection.
However, the results of such c rly inspections peric =c.d oefore the original required time interval has clapsed (nominal ti=e less 251) =ay not be used to lengthen the required inspection intervcl. Any inspection whose results require a shorter inspection interval will override the previous schedule.
Experience at operating facilities has shown that the required surveillance program should assure an acceptable level of snubber perfor:ance provided that the seal materials are compatible with the operating environment.
Snubbers containing seal raterial which has not been demonstrated by operating experience, lab tests or analysis to be co:patible with the operating envircnment' should be inspected more frequently (overy conth) until material compatability is confimed or an appropriate changeout is completed.
Examination of defective snubbers at reactor facilitics and material tests perfo =ed at several laboratories (Reference 1) has shown that millable gum polyureth:.no deteriorates rapidly under the te=perature and noisture conditions present in mahy snubber locations.
Although colded polyurethanc exhibits greater resistance to these conditions, it also may be unsuitabic for application in the' higher temperature environments. Data are not currently available to precisely define an upper temperature limit for the solded polyurethanc.
Lab tests and in-plant cxperience indicate that seal materials are availabic, primarily ethylene propy.lene ISla
s BASES:
3.6.I and 4.6.I s
=
Hydraulic Snubbers (cont'd) compoonds, which should give satisfactory. performance c?4er the most severe conditions expected in reactor installations.
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To further increase the assurance of snubber reliability, functional tests shoul_'
be performed once each refueling cycle.
U.ese tests will include stroking of the snubbers to verify proper piste. =ovement, lock-up and biced. Ten percent or ten. snubbers, whichever is less, represents an adequate sample for such rests.
Observed failures on these samples should require testing of additional units.
Snubbers in high radiation areas or those especially difficult to re ove need not be selected for functional tests provided operability was previously verified.
To complement the visual external inspections, disassembly and internal examination for component datage and abnormil seal degradation should be performed.
The examination of two units, each refueling cycle, selected from relatively severe environments should adequately serve this purpose.
Any observed wear, breakdcun or deterioration will provide a basis for additional inspections.
(1)
Report H..R. Erickson, Bergen Paterson to K. R. Go11er, NRC, October 7, 1974
Subject:
- ydraulic Shock Sway Arrestors l
l l
l 151b
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