ML19317D691
| ML19317D691 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 06/30/1975 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML19317D684 | List: |
| References | |
| NUDOCS 7912060915 | |
| Download: ML19317D691 (5) | |
Text
j LIMITING CONDITION FOR OPERATION SURVEILIANCE REQUIRDENT 3.6.I Hydraulic Snubbers 4.6.I Hydraulic Snubbers i
1.
During all modes of operation The following surveillanc*e requirements j
except Cold Shutdown and Refuel, apply to'all hydraulic snubbers except 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 seal material has been dcconstrated by 2.
The hydraulic snubbers listed operating experienec, lab testing in Tabic 3.6.I are not required or analysis to be cc:pa'tible to protect the primary coolant with the operatin; cnvironment system or any other safety shal.1 be visually ir.spected to related system or component verify their operability in and are therefore exempt from accordance with the follo'ing these specifications.
schedule:
l 3.
From and after the time that Number of Snubbers Next Required l
a hydraulic snubber is determined Found Inoperable Inspection to be inoperabic, continued During Inspection Interval reactor operation is permissible or During Inspection only during the succeeding 72 Interval i
j hours unless the snubber is sooner i
made operabic.
0 18 months 1 230 33 1
12 sonths + 25%
i 4.
If the requirements of 3.6.I.1 2
6 nonths T 23',
and 3.6.I.3 cannot be met, an 3,4 124 days
[23%
orderly shutdown shall be initiated 5,6,7 62 6cys
+ 23',
and the reactor shall be in a
>8 31 days
[250 cold shutdown condition within
- 36. hours.
The required inspc.-:icn interval shall not be lengt't..:ned nore than 5.
If a hydraulic snubber is deternined one step at a tinc.
to be inoperable while the reactor is in the shutdown or refuel mode, Snubbers may be cat.;orized in the snubber shall be made operable two groups, "accesi:. sic" or prior to reactor startup.
"inaccessibic" basc. on their accessibility for. :.nspection i
during reactor oper.. tion.
These two groups r.a: be inspected independently according to the l
l above schedule.
h l
2.
All hydraulic snubbers whose seal i
materials have not been i
demonstrated to be cocpatible with the operating environment shall be visually inspected l
j j
for operability every 31 days.
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LIM' IRING CONDITION FOR OPEF 10N SURVEILLANCE REO'
~! DENT 4.6.I ilydraulic Snubbers (ccnt'd) 3.
The initial inspection shall be perforr.ed within 6 months from the date of issuance of these specifi-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.
l 4.
Once cach refueling cycle, a repre-sentative sampic of 10 snubbers or approximately 10% of the snubbers, whichever is less, shall be i
functionally tested for operability ;
e including verification of proper i
piston mcvement, lock up and biced. l For each unit and subsequent i
unit found inoperabic, an additional!
10% or ten snubbers shall be so
- 11 tested until no more failures are found or all units have been tested.,
5.
Once cach refueling cycle at 1 cast
,two representative snubbers from a relatively severe environment shall be completely disassembled i
and examined for damage and i
abnormal seal degradation.
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1 TABLE 3.6.I i
N;w Boston Edison Co. No.
Location Elevation S-1-3Q-1 kain Steam Line A 24'9" S-1-30-2 Main Steam Line A 24'9" S-1-30-3 Main Stean Line B 24'9" S-1-30-4 Main Steam Line B 24'9" S-1-30-S Main Stean Line C 24'9" S-1-30-6 Main Steam Line C 24'9" S-1-30-7 bbin Stcan Line D 24'9" S-1-30-8 hhin 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-IS To Stop Valves 39'3" S-1-10-16 To Stop Valves 24'9" S-1-3-17 Steam By-Pass 40'3" S-1-3-18 Steam By-Pass 40'3" S-1-3-19 Steam 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 Point 21' S-1-10-26 A Train Over 2nd Point 21' S-1-10-27
/ Train Over 2nd Point 21' S-1-10-28 A Train Over 2nd Point 21' S-1-10-29 A Train over 1st Point 21' S-1-3-38 Air Ejectors 34' S-1-3-39 Air Ejectors 25' l
S-1-3-40 Air Ejectors 34' l
S-1-3-41 Air Ejectors 34' S-1-3-42 Air Ejectors 35' l
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BASES.:
3.6.I and 4.6.I Ilydraulic Snubbers Snubbers are designed to prevent unrestrained pipe motion under dynamic loads as cight occur during an carthquake or severe transient, while allowing normal thermal motior,during startup and shutdown. The consequence of an inoperable snubber is cn increase in the probability of structural damage to piping as a result of a seismic 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 er component be operable during reactor operation.
Because the snubber protection is required only during relatively low probcbility cvents, a period cf 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 peruit an orderly shutdown consistent with standard operating procedures.
Since plant startup should not commence with knowingly defective safety related equipment, Specification 3.6.I.5 prohibits startup with inoperabic snubbers.
All safety related hydraulic snubbers are visually inspected for overall integrity and operability. The inspection will include verification of proper orientation, adequate hydraulic fluid level and proper attachment of snubber to piping and
.11 structures.
The inspection frequency is based upon maintaining a constant level 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 time interval for the next required inspection.
Inspectiou perlormed before that interval has elapsed may be used as a new reference point to cctermine the next inspection.
However, the results of such cc.rly inspections pericrc.cd oefore the original required time interval has elapsed (nominal time less 251) may not bc used to lengthen the required inspection interval.
Any inspection whose results j
require a shorter inspection interval will override the previous schedule i
Experience at operating facilities has shown th.t the required surveillance program j
should assure an acceptable level of snubber performance provided that the seal materials are compatible with the operating environment.
I Snubbers containing scal
- material which has not been demonstrated by operating experience, lab tests or analysis to be compatible with the operating envircnment should be inspected more frequently (every month) until material compatability is confimed or an appropriate changeout is completed.
i Examination of defective snubbers at reactor facilities and material tests performed at several laboratories (Reference 1) has shown that millable gum polyureth.nc deteriorates rapidly under the temperat'ure and moisture conditions present in many snubber locations. Although molded polprethane 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 deilne en upper temperature limit for the molded polyurethanc.
1.ab tests and in-plant experience indicate that seal materials are availabic, primarily ethylene propyJene t
151a
BASES:
3.6.1 and 4.6.I_
s Hydraulic Snubbers (cont'd) e-4nr the most severe conditions componnds, which should give satisfactory performance expected in reactor installations.
functional tests show;.'
To further increase the assurance of snubber reliability,These tests will~ include stroking of the be performed once each refueling cyc1:.
lock-up and biced.
Ten percent or
- movement, snubbers to verify proper piste.
ten. snubbers, whichever is less, represents an adequate sample for such tests.
11 Observed failures on these samples should require testing of additional units.
Snubbers in high radiation areas or those especially difficult to remove need not be selected for functional tests provided operability was previously verified.
To complement the visual external inspections, disassembly and internal examination The for component damage and abnormal seal degradation should be performed.
examination of two units, each refueling cycle, selected from relatively severe cnvironments should adequately serve this purpose.
Any observed wear, breakdown or deterioration will provide a basis for additional inspections.
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I Report H. R. Erickson, Bergen Paterson to K. R. Goller, NRC, October 7, 1974 (1)
Subject:
- ydraulic Shock Sway Arrestors 151b 4