ML17037C175

Letter Regarding Approved Model Technical Specifications Relating to Hydraulic Snubbers and an Enclosed Copy of Revised Model Technical Specifications and Bases

ML17037C175
Person / Time
Site:	Nine Mile Point
Issue date:	12/24/1975
From:	Lear G Office of Nuclear Reactor Regulation
To:	Rhode G Niagara Mohawk Power Corp
References
Download: ML17037C175 (14)

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DISTRIBUTION:

NRC PDR 0~0 ~

Local PDR e Docket ORBft3 Rdg Docke No. 50-220 KRGoller/TJCarter GLear JGuibert Niagara Mohawk Power Corporation BCBuckley ATTN: Mr. Gerald K. Rhode Cparrish Vice President - Engineering OELD 300 Erie Boulevard West OI6E (3)

Syracuse, New York 13202 ACRS (16)

TBAbernathy Gentlemen: JRBuchanan DEisenhut RE: NINE MILE POINT UNIT 1 Gray file By letter dated October 24, 1975, we transmitted to you approved model technical specifications relating to hydraulic snubbers which have been incorporated into your Nine Mile Point Unit 1 Technical Specifications. As a result of comments that we received from licensees and further consideration by ourselves, we have revised the model technical specifications slightly to provide some relaxation and clarification of the requirements. The revisions consist of:

(1) deleting the requirement for periodic disassembly and inspection of snubbers, (2) provisions for installing additional safety related snubbers without prior NRC approval; and, in order to clarify the intent of the specifications, (3) specifying that the visual inspection of snubbers should include the fluid reservoir, fluid connections, and any linkage connections to associated piping and anchors, and (4) enlarging the scope of Table 3.6.1 in the model technical specifications to identify safety related snubbers that are (a) in high radiation areas, (b) especially difficult to remove, (c) inaccessible during normal operation, and (d) accessible during normal operation. A copy of the revised model technical specifications and bases are enclosed.

In order that we may proceed with amending your license to incorporate these technical specification changes we request that you submit an application for license amendment to reflect the enclosed revised model technical specifications and to identify the safety related snubbers and their accessibility as required by Table 3.6.1 of the revised model technical specifications. The rationale that you use for characteri2;ing a snubber as "especially difficult to remove" or "inaccessible during normal operation" should be stated in your submittal.

Sincerely, O

DrrIC E 3P OR@t?,q Operatin Reactors Br nch 83 ORB83 dIIRNAME JGuibert:k 3e'ATE3e'RBS f """""j'75 '

of Reactor L2 censing GLeer K 12/ /g /7S 12 j'""j 12/ (4f /7S Form AEC 318 (Rev. 9.33) hZCM 0240 Q U, 81 ODVERNMENT PRINTINO DPPICEI IOT4 ddd I dd

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Niagara Mohawk Power Corporation CC:

Arvin E. Upton, Esquire LeBoeuf, Lamb, Leiby 5 MacRao 1757 N Street, N. N.

Washington, D. C. 20036 Anthony Z. Roisman, Esquire Roisman, Kessler and Cashdan 1712 N Street, N. N.

Washington, D. C. 20036 Dr. William Seymour, Staff Coordinator New York State Atomic Energy Council New York State Department of Commerce 112 State Street Albany, New York 12207 Oswego City Library 120 E. Second Street Oswego,. New York 13126 Mr. Robert P. Jones, Supervisor Town of Scriba R. D. 84 Oswego, New York 13126

LIMITING CONDITION FOR OPERATION

( i 9 0 SURVEILLANCE RE UI <.hKNT 3.6.X H draulic Snubbers 4.6.I. H draulic Snubbers

1. During all modes of operation The following surveillance requirements except Cold Shutdown and Refuel, apply to. all hydraulic snubbers listed all hydraulic snubbers listed in ~

in Table 3.6.1.

Table 3.6.1 shall be operable except as noted in 3.6.I.2 through 3.6.I.4 below. 11 hydraulic snubbers whose seal aterial has been demonstrated by 2 From and after the time;that perati'ng experience, lab testing r analysis to be compatible

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a hydraulic snubber is determined i ith the operating environment to be inopcrablc, continued reactor operation is permissible hall be visually inspected. This only during the succeeding 72 i spection shall include, but not hours unless the snubber. is sooner necessarily limited to, inspection made operable. of the hydraulic fluid reservoir, fluid connections, and linkage

3. If the requirements of 3.6.I.1 connections to thc piping and anchor to verify snubber operability

, and 3.6.I.2 cannot bc met, an orderly shutdown shall be initiated in accordance with the following and the reactor shall be in a cold shutdown condition within schedule.'umber 36 hours. of Snubbers Next Required Found Inoperable Inspection

4. If a hydraulic snubber is determined During Inspection or During Inspection Interval to be inoperable while the reactor is in the shutdown or refuel mode, Interval the snubber shall be made operable prior to reactor startup. 0 18 months + 25~o

.1 12 months + 25~o

5. Snubbers may be added to safety 2 6 months + 25'o related, systems without prior 3,4 124 days'2

+ 25~o License Amendment to Table 3.6.1 5,6,7 days + 25'o provided that safety evaluations, >8 31 days + 25'o documentation and reporting are provided in accordance with 10 Thc required inspection interval CFR 50.59 and that a revision to shall not be lengthened more than

.'fable 3,6.1 is included with a one step at a time:

subsequent License Amendment request. 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 t!>at has been demonstrated to be compatible with the operating environment shall be visually inspected for operability every 31 days .

,~4 LIMITPilG. CONDITION FOR OPERA'I SURVEILLANCE (U "".MEhT 4,6,I --Hydraulic Snubbers (cont'd)

The initial inspection shall be performed within 6 months from the date of issuance of these specifi-cations. For the purpose of entering'he schedule in Specification 4.6.I.l, it shall be assumed that the facility had been on a 6 month inspection interval.

'l 4, Once each refueling cycle, a repre-sentative sample of 10 snubbers or approximately 10~~ of the snubbers, whichever is less, shall be functionally tested for operability including verification of proper piston movement, lock up and bleed.

For each unit and subsequent unit found inoperable, an additional 10~ or ten snubbers shall be so tested until no more failures are found or all units have been tested.

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BASBS:

3. 6. I and 4. 6. I H draulic Snubbers Snubbers are designed to prevent unrestrained pipe motion under dynamic loads as might occur during an earthquake or severe transient, while ale.owing normal thermal motion during startup and shutdown. The consequence of an inoperable snubber is ap 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.

Because the snubbe'r protection is required only during relatively low prob"bility 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 or rcplacerI>ents. 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 shutdoim condition will permit an orderly shutdown consistent with standard operating procedures.

Since plant startup should not commence with knowi.ngly defective safety related equipment, Specification 3,6.I.4 prohibits startup with inoperable 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 Stl'Uctul'CS .

The inspection frcquenc> is based upon maint'aining a constant level of snubber protection. Thus the required inspection interval varies inversely with thc observed snubber failures. The number of inoperable snubbers found during a required inspection determines the time interval for thc next required inspection. Inspections;1crformed before that interval has elapsed may be used as 'e>> reference point to determine the next inspection. However, thc 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 reqllircd inspection 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 >>hich has not been demonstrated by operating experience, lab tests or analysis to be compatiUle with the operating environment should be inspected more frequently (every month) until materi .1 compatibility is confirmed or an appropriate changeout i.s completed.

examination of defective snubbers at reactor facilitics and material tests perfor ed at several laboratories (Reference 1) has shown that millable gna polyurethane deteriorates rapidl> under the temperature and moisture conditions present in many snubber locations. Although molded pol>urethane exhibits greater resistance to these conditions, it also may be unsuitable for application in the higher temperature environments. Data are not currently availablc to precisely define

'an upper temperature limit for the molded polyurctllanc. Lab tests and in-plant experience indicate that seal materials, are available', pr'imari:1>'thylene propvpene

0 BASES:

3.6,I and 4.6.I H draulic Snubbers (cont'd) compounds, which should give satisfactory performance under the most severe conditions expel.ted in reactor installations.

To further increase the assurance of snubber reliability, functional tests should be performed once each refueling cycle, These tests will include stroking of the s nubbcrs to verify proper piston movement, lock-up and bleed. Ten percent or t en snubbers, whichever is less, represents an adequate sample for such tests.

Observed failures on these samples should require .testing of additional units.

Those snubbers designated in Table 3.6.1 as being in high radiation areas or e specially difficult to remove need not be selected, for'unctional tests provided operability was previously verified.

(1) Report H. R. Erickson, Bergen Paterson'to K. R. Gollcr, NRC, October 7, 1974

Subject:

Hydraulic Shock Sway Arrestors

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Table 3.6.1 SAFETY RELATED HYDRAULIC SNUBBERS Location Elevation Snubber in High Snubbers Snubbers Snubbers Snubber No. Accessible Radiation Area Especially Inaccessible During Shutdown Difficult to During Normal , During Normal Remove Operation Operation 1 Main Steam Line X

2 Main Steam Line 3 RHR 953'50'64'64'22' 4 RHR etc, Recirculatory pipe

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