ML20024G641
| ML20024G641 | |
| Person / Time | |
|---|---|
| Site: | Monticello  |
| Issue date: | 07/11/1975 |
| From: | Ziemann D Office of Nuclear Reactor Regulation |
| To: | Mayer L NORTHERN STATES POWER CO. |
| References | |
| NUDOCS 9102130563 | |
| Download: ML20024G641 (7) | |
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Arthur P,enquist, Erquire The T.nylronmental Conservation
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Ant hony .1;oi st:an, Esquire i
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' BASES :_
3.6.1 and 4.6.1_
[lydraulieSnubbers_(cont'd) conditions compounds, which should give satisfactory performance under the most expected in reactor installations, l
h ld To further increase the assurance of snubber reliability, functional tests be perforced once each refueling cycle.
lock-up and bleed. Ten percent or snubbers to verify proper piston movement, ten. snubbers, whichever for such tests.
I Observed failures on these sa ples should require testing of additional un Snubbers in high radiation areas or those especially difficult to remove ified.
not be selected for functional tests provided operab i
The for component damage and abnormil seal degradat l
r environtents should adequately serve this purpose.or deterioration l
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l Report H. R. Erickson, Bergen Paterson to K. R. Goller, NRC, Oc l
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Subject:
Hydraulic Shock Sway Arrestors l
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BASES:
3.6.! and 4.6.1 Hydraulic Snubbers Snubbers are designed to prevent unrestrained pipe motion under dynamic loads as might occur during an earthquake or severe transient, while allowing normal thermal The consequence of an inoperabic snubber is motion during startup and shutdown.
an increase in the probability of structural damage to piping as a reruit of a seismic It is therefore required that all hydraulic or other event initiating dynamic loads.
snubbers required to protect the primary coolant system or any other safety system or co:ponent be operabic during reactor operation.
Because the snubber protection is required only during relatively low prob:bility IcplaceLents.
In case a events, a pericd 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 c.
shutdown is required, the allowance 0136 hours0.00157 days <br />0.0378 hours <br />2.248677e-4 weeks <br />5.1748e-5 months <br /> to reach a cold shutdcwm ccndition will permit an orderly shutdown censister.t with stanaard operating procei..re:.
Since plant startup should not ce==ence with hnowin;;y defective safety ra;atcd equipment, Specification 3.6.1.5 prohibits startup with inoperable snubbers.
All safety related hydraulic snubbers arc visually inspected for overall integrity The inspection will include verification of proper orientation, and operability.
adequate hydraulic fluid level and proper attachment of snubben to piping and structures.
The inspection frequency is based upon maintaining a constant icyc1 of snubber Thus the requircd 2nspection interval varies inversely with the observed protectien.
The number of inoperable snubbers found during a required inspection snubber failures.
determines the time interval for the next required inspection, inspections performed interval has elapsed may be used as a new reference point to determine before that However, the results of such early inspections perfor:cd before the next inspection.
the original required time interval has elapsed (nominal time less 25'.) may not be used to lengthen the required inspection interval. Any inspection whose results require a shorter inspection interval will override the previous schedu.le.
I Experience at operating facilities has shown that the required surveillance program should assure an acceptab4e level of snubber performance provided that the seal f
materials are co:patibic with the operating environment.
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Snubbers containing seal material which has not been demonstrated by operating experience, lab tests or analysis to be compatibic with the operating environment should be inspected more frequently (every month) until material compatability is confirmed or an appropriate changeout is ceepleted.
Examination of defective snubbers at reactor facilities and material tests perfor=ed at several laboratories (Reference 1) has shown that millable gum polyurethane deteriorates rapidly under the te=perature and moisture conditions present in Although molded polyurethane exhibits greater resistance many snubber locations.
to these conditions, it also may be unsuitable for application in the higher Data are not currently available to precisely define temperature environments.
Lab tests and in-plant an upper temperature limit fer the molded polyurethane.
experience indicate that seal materials are available, primarily ethylene propylene l
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TABLE 306. !
Snubber No.
Location Elevation 24'9" S-1-30-1 Hsin Steam Line A S-1-30-2 Main Steam Line A 24'9" 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 Steam Line D 24'9" S-1-30-8 Main Steam Line D 28'6" S-1-10-9 From Stop Valves 28'6" S-1-10-10 Prom Stop Valves 39' S-1-10-11 To Stop Valves 39' S-1-20-12 To Stop Valves 39'3" S-1-10-13 To Stop Valves 24'9" S-1-3-14 To Stop Valves 39'3" S-1-3-15 To Stop Valves 24'9" S-1-10-16 To Stop Valves 40'3" S 1-3-17 Steam By-Pass 40'3" S-1-3-18 Steam By-Pass 38'7" S 1-3-19 Steam By-Pass S-1-10-20 B Train Over 2nd Point 21' S-1-10-21 B Train Over 2nd Point 21' 21' S-1-10-22 B 1 rain Over 2nd Point S-1-10-23 B 1 rain 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 A 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' 34' S-1-3-38 Air Ejectors 25' S-1-3-39 Air Ejectors 34' S-1-3-40 Air Ejectors 34' S-1-3-41 Air Ejectcrs 35' S-1-3-42 Air Ejectors l
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'N SURVEILIANCE RE00' NEhT o
yM9TINGCOND2TIONFOROPERN 4.6.1 Hydraulic Snubbers _ (cont'd) 3.
The initial inspection shall be perforced within 6 conths from the date of issuance of these specifi-cations.
For the purpose of entering the schedule in Specification 4.6.1.1, it shall be assumed that the facility had been on a 6 month inspection interval.
4.
Once each refueling cycle, a repre-sentative sample of 10 snubbers or approximately 10% of the snubbers, whichever is less, shall be functionally terted for operability including verification of proper piston movement, lock up and bleed.
For each unit and subsequent unit t'ound inoperabic, an additional 10% or tea snubbers sha'.1 be so
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tested until no more failures are found.or all unitt have been tested.
5.
Once each refueling cycle at Icast from
,two representative snubbers a relatively severe env:ronment shall be completely disassembled 2nd examined for damage and abnormal seal degradation.
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- fMITING COND2 TION FOR OPERNa40M SURVEII. LANCE.dQUIREMENT 1,
3.6.! Hydraulic Snubbers 4.6.I Hydraulic Snubbers 1.
During all modes of operation 1he following surveillance requirement i 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 snubbers whose seal mat *erial has been demonstrated by 2.
The hydraulic snubbers listed operating experience, lab testing in Table 3.6.I are not required or analysis to be ccapatible to protect the prir.ary coolant with the operating environment system or any other safety shall be visually inspected to related syften or component Verify their operability in.
and are therefore exempt from accordance with the following schedule:
these specifications.
3.
From and after the time that Number of Snubbers Next Required a hydraulic snubber is detemined Found Inoperable Inspection i
to be inoperabic, continued During Inspection Interval l
reactor operation is permissible or During Inspection only during the succeeding 72 Interval hours unless the snubber is sooner made operable.
0 18 months 1 2 5',
33 1
12 months + 25'.
4 If the requirements of 3.6.1.1 2
6 months 7 25',
and 3.6.I.3 cannot be net, an 3,4 124 days 7 2M orderly shutdown shall be initiated 5,6,7 62 days 7 2y.
and the reactor shall be in a
>8 31 days 7 2.%
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cold shutdown condition within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />.
The required inspection interval shall not be lengthened more than 5.
If a hydraulic snubber is determined one step at,a tico, to be inoperable while the reactor is in the shutdown or refuel mode, Snubbers may be cato2ori:ed in the snubber shall be made operabic two groups, " access.ble" or
" inaccessible" based on their prior to reactor startup.
accessibility ft,r inspection during reactor operation.
These two groups may be inspected independently according to the above schedule.
2.
All hydtaulic snubbers whose seal,
materials have not been demonstrated to be compatible with the operating environment shall be visually inspected for operability every 31 days.
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