ML19319E077
| ML19319E077 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 01/20/1976 |
| From: | SACRAMENTO MUNICIPAL UTILITY DISTRICT |
| To: | |
| Shared Package | |
| ML19319E076 | List: |
| References | |
| NUDOCS 8003310587 | |
| Download: ML19319E077 (5) | |
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RANCHO SECO UNIT I TECHNICAL SPECIFICATIONS Regulatory Docket File 4.14 SAFETY SYSTEMS HYDRAULIC SNUBBERS Applicability ggg'Ja i,tM Tha 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 experience, laboratory testing or analysis to be compatible with the operating environment shall be visually inspected.
This inspection shall include, but not necessarily be limited to, inspection of the hydraulic fluid reservoir, fluid connections and linkage con-nections to the piping and anchor to verify snubber operability in accordance with the following schedule:
Number of Snubbers Found inoperable during inspection Next Required or during inspection Interval inspection Interval 0
18 months + 25%
1 12 months T 25%
2 6 months T 25%
3,4 4 months T 25%
5,6,7 2 months T 25%
>8 1 month i25%
The required inspection interval shall not be lengthened more than one step at a-time.
Snubbers may be categorized in two groups, " accessible".or " inaccessible" based on their accessibility for inspection during reactor operation.
These two groups may be inspected independently according to the above schedule.
2.
All hydraulic snubbers whose seal materials are other than ethylene propylene or other material that has been demonstrated to be compatible with the operating environment shall be visually inspected for operability every 31 days.
3.
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-interval.
4.
At each refueling interval, at least one unit for each type of seal which is exposed to the nest adverse environment (radiation and tempera-tures), shall be. disassembled and seal material physical properties ifphysicalpropertiesnotedindicatesealsareaproachinge[nd [
. evaluated, i
useful, life, as recommended by snubber manufacturer, all seal 4s0 kw
similar atmosphere shall be replaced not later than the next refueling
- interval, in addition, if seal replacement is necessary, per above requirements, a sample unit from an area having less harsh environment 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 seismie 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.
in-All safety related hydraulic snubbers are visually inspected for overall tegrity and operability. The inspection will include verification of proper orientation, adequate hydraulic fluid level and proper attachment of snubber to piping and structures.
level of snubber The inspection frequency is based upon maintaining a constant protection. Thus the required Inspection interval varies inversely with the observed 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 interval has elapsed may be used as a new reference point to determine the next inspection.
However, the results of such early inspections performed before the original required time interval has elapsed (nominal time less 25t) 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 lab tests, or analysis to be compatible with the operating environment experience, should be inspected more frequently (every month) until material compatibility is confirmed or an appropriate changeout is completed.
Examination of defective snubbers at reactor facilities and material tests per-formed at several laboratories (Reference 1) has shown that millable sum poly-urethane deteriorates rapidly under the temperature and moisture conditions in many snubber locations.
Although molded polyurethane exhibits greater present resistance to; these conditions, it also may be unsuitable for application in the higher temperature environments.
Data are not currently available to precisely Lab tests and
. define an upper temperature limit for the molded polyurethane.
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.
4-47a
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To further increase the assurance of snubber reliability, tests should be per-formed once each refueling cycle.
These tests will include disassembling to verify proper seal integrity.
Observed failures on these sampics should requirc testing of additional units.
Snubbers in high radiation areas or those especially difficult to remove need not be selected for tests provided operability was previously verified by test inspections during the previous interval.
Five such units will be selected for inspection and the testing shall include one such snubber each refueling interval.
To complement the visual external inspections, disassembly and internal examination for component damage and abnormal seal degradation should be performed.
The examination of snubbers, each refueling cycle, selected from relatively severe environments should adequately serve this purpose.
Any observed wear, breakdown or deterioration will provide a basis for additional inspections.
(1)
Report H. R. Erickson, Bergen Paterson to K. R. Goller, NRC, October 7, 1974 Subj ect :
Hydraulic Shock Sway Arrestors 4-47b
w TABLE 4.14-1 Snubbers Accessible During Power Operations Lict No.
- I.D. No.
List No.
I.D. No.
1 MS 20528 SW 1 30 4SW 20024-3A 2
MS 20521 SW 11 31 4SW 26101-2 3
MS 20520 SW 3 32 4SW 26101-6 4
MS 20521 SW 13 33 4SW 25023-5A 5
MS 20520 SW 5 34 4SW 26101-8A 6-MS 20521 SW 14 35 4SW 25023-8A 7
-MS 20520 SW 13A 36 4SW 26100-3 8
MS 20520 SW 6 37 45W 26100-1A 9
-MS 20526 SW 9 38 4SW 26022-13A 10 95W 30709-3A 39 45W 26025-43 11 9SW 30708-4 40 4SW 23620-3A-12 9SW 30708-5A 41 4SW 53520-3 13 95W 30709-4 42 4SW 29101-1A 14 9SW 30709-3 101 MS 20520 SW 19 15 SSW 20530-7A 102 MS 20521 SW 20 16 SSW 20529-3A 103 MS 20521 SW 22 17 SSW 53520-3 104 MS 20520 SW 21 18 SSW 32141-1A 105 10 SW 20553-1A 19 5SW 32141-2 106 SSW 20529-1A 20 10 SW 20530-3A 107 5SW 20529-4A 21 12 SW 20530-3A 108 SSW 20530-8 22 7SW 32120-1B 109 7SW 30800-6 23
'7SW 32120-1A 110
-75W 30800-8 24 75W 32120-1C 111 7 SW 30800-12 25 MS 20550 SW 1 112 75W 30800-14 26 MS 20558 SW 1 113 7SW 30804 27 MS 20532 SW 1 114 7SW 30805-2 28~
MS 20531 SW 1 115 SSW 23803-4A 29-7SW 32140-2 116 4SW 60014-4A
- Numbers 1 to 99 designate Bergan-Patterson units Numbers 101-to 199 designate Grinnel units PS, P6 and P7 are on the Pressurizer Surge Line SS-l ' to SS-24' are _on the Reactor Coolant Pumps 4-47c.
TABLE 4.14-1 Snubbers Inaccessible During Power Operations
' List No.
- I.D. No.
List No.
I.D. No.
PS 1 SW 10' BsW-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 SW 20025-3 128 1 SW 21005-8
)
51 1 SW 20025-1A 129 1 SW 23822-7B l
52
~ 1 SW 26020-5A 130 1 SW 21028-2 53 1 SW 26524-4A 131 1 SW 26020-6A l
54 1 SW 50060-8A 132 1 SW 20082-12A I
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 21501-20 59 1 SW 50063-2A 137 1 SW 21501-28 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 l
65 1 SW 29125-7C SS-5 SS-5 l
66 MS 20523 SW2 SS-6 SS-6 67 MS 20521 SW17 ss_7 33_7 68 1-SW 21925-9A SS-8 SS-8 69 1 SW 50050-2A ss_9 SS-9 70 MS.20520 SW 18 33_10 ss_10 71 MS 20522 SW2 ss_11 33_11 72 1 SW 50060-3A SS-12 SS-12
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73 1 SW 32140-4 SS-13 SS-13
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74 1 SW 32140-2 ss_14 33_14 l
75 1 SW 32141-4 SS-15 SS-15 l
76 1 SW 32141-2 SS-16 SS-16 77 1 SW 50053-2A ss-17 SS-17 117 1 SW 22000-12 SS-18 SS-18 118 1 SW 22000-2A SS-19 SS-19 l
i 119 1 SW 22001-2 SS-20 SS-20 120 1 SW 21007-7 SS-21 SS-21 p
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 l
!* Numbers -l to 99 designate Bergan-Patterson units L Numbers 101 to 199 designate Grinnel units PS,.P6 and P7'are on the Pressurizer Surge Line S5-1 to 55-24 are on the. Reactor Coolant Pumps.
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