ML19317G876
| ML19317G876 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 07/31/1975 |
| From: | SACRAMENTO MUNICIPAL UTILITY DISTRICT |
| To: | |
| Shared Package | |
| ML19317G875 | List: |
| References | |
| NUDOCS 8004020537 | |
| Download: ML19317G876 (4) | |
Text
L
_ RANCHO SECO UNIT 1 i
1 TECHNICAL SPECIFICATIONS (J
4.14 SAFETY SYSTEMS HYDRAULIC SNUBBERS-Applicability
^
The following surveillance requirements apply to hydraulic snubbers listed in Table 4.14-1.
Objective To verify that the hydraulic snubbers will perform their design function.
Specification 1.
All hydraulic snubbers whose seal material has been demonstrated by operating expertence, laboratory testing or analysis to be compatible with the operating environment shall be visually inspected to verify their operability in accordance with the following schedule:
/'
Number of Snubbers Found Inoperable during Inspection Next Required or during Inspection Interval Inspection interval 0
18 nonths + 25%
1 12 months T 25%
2 6 months T 25%
3, 4 4 months + 25%
5, 6, 7 2 months T 25%
>8 1 month + 25%
The required inspection interval shall not be lengthened more than one step at a time.
Snubbers are catagorized in two groups, " accessible" or " inaccessible" during reactor operation. These two groups are inspected independently uccirding to the above schedule.
2.
The initial inspection shall be performed within 6 months from the date of issuance of these specifications.
For the purpose of entering the schedule in Specification 4.14.1, it shall be assumed that the facility had been on a 6 month inspection.
3 All hydraulic snubbers whose seal materials have not been demonstrated to be compatible with the operating environment shall be visual!,
inspected for operabili ty monthly.
4.
At each refueling interval, at least one unit containing ethelene pro-pylene seals and one unit containing polyurethane seals, which are exposed to the mn-t adverse environment (radiation and temperatures),
shall be disassembled and seal material phys: cal properties evaluated.
If physical 'roperties noted Indicate seals are approaching end of useful life, as recommended by snubber manufacturer, all seals in units in a 4-47 8004020 N h
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similar' atmosphere shall ba replaced not later than the next refueling interval.
In addition, if seal replacement is necessary, per above requirements,' sample units from areas having less harsh environnent shall be disassembled and need for seal replacement determined.
BASES:
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 motion during.startup and shutdown.
The consequence of an inoperable snubber is an increase in the probability of structural damage 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 primary coolant system or any other safety system or component be operable during reactor operation.
All safety related hydraulic snubbers are visually inspected for overall in-tegrity and operability. The inspection will include verification of proper orientation, adequate hydraulic fluid level and proper attachment of snubber to piping and structures.
The inspection frequency is based upon maintaining a constant level of snubber protection. Thus the required inspection interval varies inversely with the obscived snubber failures.
The number of Inoperable snubbers found during a required inspection determines the time interval for the next required inspection.
Inspections performed before that interva) has elapsed may be used as a new reference point to determine the next inspec+ ion.
However, the results of such early inspections performed before the original required time interval has elapsed (nominal time less 25%) may not be used to lengthen the required inspec-tion interval.
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 performance provided that the seal materials are compatible with the operating environment.
Snubbers containing seal material which has not been demonstrated by operating experience, lab tests, or analysis to be compatible with the operating environnent should be inspected more frequently (every month) until material compatibility is con'irmed or an appropriate changeout is completed.
Examinat ion of defective snubbers at reactor facilities and material tests per-formed at several laboratories (Reference 1) has shown that millabic gum poly-urethane de.eriorates rapidly under the temperature and moisture conditions present in many snubber locations.
Although molded polyurethane exhibits greater resistance to these conditions, it also may be unsuitable for application in the higher temperature environments.
Data are not currently available to precisely define an upper temperature limit for the molded polyurethane.
Lab tests and in plant experience indicate that seal materials are available, primarily ethylene propylene compounds, which should give satisfactory performance under the most' severe conditions expected in reactor installations.
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T furth[rIncrcsathacssurcncocfsnubb;rrelitbility,tsstsshouldbaper-
' f rmed onco cach - refueling cycle. Thsse tests will includa disassembling to verify proper seal integrity.
Observed failures on-these samples should require
.. testing of additional. uni ^s.
Snubbers in high. radiation areas or those especially dif ficult. to remove need not be selected for tests provided operability was-previously verified. To complement the visual external inspections, disassembly tnd internal r xamination for component damage and abnormal seal degradation should be performed.
The examination of two units, each refueling cycle, selected from relatively severe environments should acequately serve this purpose.
Any
- observed wear., breakdown or deterioration will provide a basis for additional inspections.
9 (1)
Report H. R. Erickson, Bergen Paterson to K. R. Coller, NRC, October.7, 1974
Subject:
Hydraulic Shock Sway Arrestors l.
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D TABLE 4.14-1 Snubbers Inaccessible During Power Operations List No.
.I.D.
No.
List No.
I.D. No.
PS 1 SW 10' B&W-5 125 1 SW 21021-3 P6 1 SW 10 B&W-6 126 1 SW 23823-7A P7 1 SW 10" B&W-7 127 1 SW 21025-9A
.50 1 Eni 20025-3 128 1 SW 21005 51 1 SW 20025-1A 129 1 SW 23822-7B 52 1 SW 26020-5A 130 1 SW 21028 53 1.SW 26524-4A 131 1 SW 26020-6A 54 1 SW 50060-8A 132 1 SW 20082-12A 55 1 SW 22000-9 133 1 SW 26521-2A 56 1 SW 26021-5A 134 1 SW 21025-6 57 1 SW 26021-7A 135 1 SW 23823-13A 58 1 SW 26021-11A 136 1 SW 21001-20 59 1 SW 50063-2A 137 1 SW 21001-28 60 1 SW 23823-8 138 1 SW 50050-6A.
61 1 SW 23620-15A SS-1 SS-1 62 1 SW 23626-3A SS-2 SS-2 63 1 SW 29122-28A SS-3 SS-3 64 1 SW 29125-7A SS-4 SS-4 65 1 SW 29125-7C SS-5 SS-5
-66 MS 20523 SW2 SS-6 SS-6 67 MS 20521 SW17 SS-7 SS-7 68 1 SW 21925-9A SS-8 SS-8 69 1 SW 50050-2A SS-9 SS-9 70 MS 20520 SW 18 SS-10 SS-10 71 MS 20522 SW2 SS-11 SS-11 72 1 SW 50060-3A SS-12 SS-12 l
73 1 SW 32140-4 SS-13 SS-13 74 1 SW 32140-2 SS-14 SS-14 75 1 SW 32141-4 SS-15 SS-15 76 1 SW 32141-2 SS-16 SS-16 77 i SW 50053-2A SS-17 SS-17 l
117 1 SW 22000-12 SS-18 SS-18 118 1 SW 22000-2A SS-19 SS-19 119 1 SW 22001-2 SS-20 SS-20
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l 120 1 SW 21007-7 SS-21 SS-21 121 1 SW 21022-5 SS-22 SS-22 122 1 SW 21006-6A SS-23 SS-23 123 1 SW 23626-1A SS-24 SS-24 124 1 SW 21022-1 i
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