ML20206J453

Revs to Catawba Nuclear Station Selected Licensee Commitments Manual

ML20206J453
Person / Time
Site:	Catawba
Issue date:	04/22/1999
From:	DUKE POWER CO.
To:
Shared Package
ML20206J448	List: ML20206J443 ML20206J453
References
PROC-990422, NUDOCS 9905120229
Download: ML20206J453 (11)

Text

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AUXILIARY SYSTEMS

~O 16.9-13 SNUBBERS COMMITMENT:

All snubbers shall be OPERABLE. The only snubbers excluded from the requirements are those installed on non safety-related systems and then only if their faliure or failure of the system on which they are installed would have no adverse effect on any safety-related system.

APPLICABILITY: -

MODES 1,2,3, and 4. MODES 5 and 6 for snubbers located on systems required OPERABLE in those MODES.

REMEDIAL ACTION:

With one or more snubbers inoperable, within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> replace or restore the inoperable snubber (s) to OPERABLE status and perform an engineering evaluation per TESTING REQUIREMENT 16.9-13.g on the attached component or declare the attached system inoperable and follow the appropriate Technical Specification O ACTION statement for that system.

TESTING REQUIREMENTS:

Each snubber shall be demonstrated OPERABLE by performance of the following augmented inservice inspection program,

a. Insoection Tvoes As used in this specification, " type of snubber" shall mean snubbers of the same design and manufacturer, irrespective of capacity.

b. VisualInspections Snubbers are categorized as inaccessible or accessible during reactor operation. Each of these categories (inaccessible and accessible) may be inspected independently according to the schedule determined by Table 16.9-13A. The visual inspection interval for each category of snubber shall be determined based upon the criteria provided in Table 16.9-13A and the first inspection interval determined using this criteria shall be based upon the previous inspection interval as established by the requirements in effect before Technical Specification Amendment 88 (Unit 1) and 82 (Unit 2).

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TESTING REQUIREMENTS (con't) -

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c. VisualInsoection Acceptance Criteria Visual inspections shall verify that: (1) the snubber has no visible indications of damage or impaired OPERABILITY, (2) attachments to the foundation or supporting structure are functional, and (3) fasteners for the attachment of the snubber to the component and to the snubber anchorage are functional.

Snubbers which appear inoperable as a result of visual inspections shall be l classified as unacceptable and may be reclassified acceptable for the purpose of establishing the next visual inspection interval, provided that: (i)  !

the cause of the rejection is clearly established and remedied for that particular snubber and for other snubbers irrespective of type that may be generically susceptible; and (ii) the affected snubber is functionally tested in the as-found condition and determined OPERABLE per Testing Requirement 16.9-13f. All snubbers found connected to an inoperable common hydraulic fluid resen/oir shall be counted as unacceptable and may be reclassified as acceptable for determining the next inspection interval provided that criterion

-(i) and (ii) above are met. A review and evaluation shall be performed and documented to justify continued operation with an unacceptable snubber. If continued operation cannot be justified, the snubber shall be declared inoperable and the REMEDIAL ACTION requirements shall be met.

d. Refuelina Outaoe inspections At each refueling, the systems which have the potential for a severe dynamic event, specifically, the Main Steam System (upstream of the main steam isolation valves) the main steam safety and power-operated relief valves and piping, Auxiliary Feedwater System, main steam supply to the auxiliary feedwater pump turbine, and the letdown and charging portion of the CVCS System shall be inspected to determine if there has been a severe dynamic event, in the case of a severe dynamic event, mechanical snubbers in that system which experienced the event shall be inspected during the refueling outage to assure that the mechanical snubbers have freedom of movement and are not frozen up. The inspection shall consist of verifying freedom-of-motion using one of the following: (1) manually induced snubber movement; or (2) evaluation of in-place snubber piston setting; or (3) stroking the mechanical snubber through its full range of travel. If one or more mechanical snubbers are found to be frozen up during this inspection, those snubbers shall be replaced or repaired before retuming to power. The requirements of Testing Requirement 16.7-13b. are independent of the requirements of this Testing Requirement.

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l TESTING REQUIREMENTS (con't) j O e. Functional Tests 1 During the first refueling shutdown and at least once per 18 months thereafter during shutdown, a representative sample of snubbers of each type shall be 3 tested using one of the following sample plans. The large-bore steam l generator hydraulic snubbers shall be treated as a separate type (population) i for functional test purposes. A .10% random sample shall be tested at least  !

once per 18 months during refueling with continued testing based on a failure evaluation. The sample plan shall be selected prior to the test period and ,

cannot be changed during the test period. The NRC shall be notified in j writing of the sample plan selected for each snubber type prior to the test j period or the sample plan used in the prior test period shall be implemented:

1) At least 10% of all snubbers shall be functionally tested either in-place or in a bench test. For each snubber of a type that does not meet the i functional test acceptance criteria of Testing Requirement 16.9-13f, an I additional 10% of all snubbers shall be functionally tested until no more failures are found or until all snubbers have been functionally tested; or

2) A representative sample of all snubbers shall be functionally tested in O accordance with Figure 16.9-13A. "C"is the total number of snubbers of a type found not meeting the acceptance requirements of Testing Requirement 16.9-13f. The cumulative number of snubbers tested is denoted by "N". At the end of each day's testing, the new values of "N" and "C" (previous day's total plus current day's increments) shall be plotted on Figure 16.9-13A. If at any time the point plotted falls in the " Accept" region, testing of snubbers of that type may be terminated. When the point plotted lies in the " Continue Testing" region, additional snubbers of that type shall be tested until the point falls in the " Accept" region or all the snubbers of that type have been tested; or

3) An initial representative sample of 55 snubbers shall be functionally tested. For each snubber type which does not meet the functional test acceptance criteria, another sample of at least one-half the size of the initial sample shall be tested until the total number tested is equal to the initial sample size multiplied by the factor,1 + C/2, where "C" is the number of snubbers found which do not meet the functional test acceptance criteria. The results from this sample plan shall be plotted using an " Accept"line which follows the equation N = 55(1 + C/2).

Each snubber point should be plotted as soon as the snubber is tested. If the point plotted falls on or below the " Accept" O

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TESTING REQUIREMENTS (con't)

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line, testing may be terminated. If the point plotted falls above the

" Accept" line, testing must continue until the point falls in the " Accept" region or all the snubbers of that type have been tested.

Testing equipment failure during functional testing may invalidate that day's testing and allow that day's testing to resume anew at a later time provided all snubbers tested with the failed equipment during the day of equipment failure are retested. The representative sample selected for the functional test sample plans sha'i be randomly selected from all snubbers and reviewed before beginning the testing.

The review shall ensure, as far as practicable, that they are representative of the various configurations, operating environments, range of size, and capacity of snubbers. Snubbers placed in the same location as snubbers which failed the previous functional test shall be retested at the time of the next functional test but shall not be included in the sample plan. If during the functional testing, additional sampling is required due to failure of only one type of snubber, the functional test results shall be reviewed at that time to determine if additional samples should be limited to the type of snubber which has failed the functional testing.

f. Functional Test Acceptance Criteria The snubber functional test shall verify that:

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1) Activation (restraining action) is achieved within tne specified range in both tension and compression, except that inertia dependent, acceleration limiting mechanical snubbers may be tested to verify only that activation takes place in both directions of travel;

2) Snubber bleed, or release rate where required, is present in both tension and compression, within the specified range;

3) For mechanical snubbers, the force required to initiate or maintain motion of the snubber is within the specified range in both directions of travel; and

4) For snubbers specifically required not to displace under continuous load, the ability of the snubber to withstand load without displacement.

Testing methods may be used to measure parameters indirectly or parameters other than those specified if those results can be correlated to the specified parameters through established methods.

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TESTING REQUIREMENTS (con't)

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FunctionalTest Failure Analysis '

An engineering evaluation shall be made of each failure to meet the functional test acceptance criteria to determine the cause of the failure. The ,

results of this evaluation shall be used, if applicable, in selecting snubbers to be tested in an effort to determine the OPERABILITY of other snubbers irrespective of type which may be subject to the same failure mode.

1 For the snubbers found inoperable, an engineering evaluation shall be performed on the components to which the inoperable snubbers are attached. The purpose of this engineering evaluation shall be to determine if the components to which the inoperable snubbers are attached were adversely affected by the inoperability of the snubbers in order to ensure that  ;

the component remains capable of meeting the designed service.

If any snubber selected for functional testing either fails to lock up or fails to move, i.e., frozen-in-place, the cause will be evaluated and, if caused by l manufacturer or design deficiency, all snubbers of the same type subject to the same defect shall be functionally tested. This Testing Requirement shall be independent of the requirements stated in Testing Requirement 16.9-13e for snubbers not meeting the functional test acceptance criteria.

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h. Functional Testino of Repaired and Replaced Snubbers Snubbers which fall the visual inspection or the functional test acceptance criteria shall be repaired or replaced. Replacement snubbers and snubbers which have repairs which might affect the functional test results shall be tested to meet the functional test criteria before installation in the unit.

Mechanical snubbers shall have met the acceptance criteria subsequent to their most recent service, and the freedom-of-motion test must have been performed within 12 months before being installed in the unit,

l. Snubber Service Life Proaram The service performance of all snubbers shall be monitored. If a service lifetime limit is associated (established) with any snubber (or critical part) based on manufacturer's information, qualification tests, or historical service results, then the service life shall be monitored to ensure that the service life is not exceeded between surveillance inspections. Established snubber service life shall be extended or shortened based on monitored test results and failure history. The replacements (snubbers or critical parts) shall be documented and the documentation shall be retained. Records of the service lives of all hydraulic and mechanical snubbers, including the date at O

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- TESTING REQUIREMENTS (con't)

O which the service life commences, and associated installation and maintenance records shall be retained for the duration of the Unit Operating License.

REFERENCES:

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1. Letter from NRC to Gary R. Peterson, Duke, Issuance of Improved Technical Specifications Amendments for Catawba, September 30,1998. 4 BASES:

All snubbers are required OPERABLE to ensure that the structural integrity of the Reactor Coolant System and all other safety-related systems is maintained during and following a seismic or other event initiating dynamic loads.

The Remedial Action (72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> requirement) was previously a Technical Specification Action Statement and as such shall not be revised without NRC review / approval as an Unreviewed Safety Question. The original Technical Specification provided the 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> period rather than immediately entering the Action Statement for the supported system (as generally required per Technical Specification LCO 3.0.6). Since the SLC is unchanged from the original Technical Q Specification the Remedial Action is to be used in lieu of TS LCO 3.0.6 to provide the same 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> period.

The Remedial Action requires that an inoperable snubber be replaced or restored within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />, and an engineering evaluation be performed per TESTING REQUIREMENT 16.9-13g on the attached component. This TESTING REQUIREMENT is applicable to snubbers which fall to meet the functional test criteria provided in 16.9-13f. An evaluation is required of each failure to determine the cause, and the potential for applicability of the failure mode to other snubbers.

Likewise an evaluation is required to determine if the attached components have been adversely affected by the functional failure of the snubber. It is noted that the evaluation is only required for snubbers that are inoperable due to a failure of the l

snubber itself to meet the functional requirements. A snubber which is inoperable  !

due solely to being disconnected from the supported component does not necessitate a component or system evaluation, provided that the snubber itself meets the requirements of 16.9-13f. In this case the only action required is that the snubber be completely restored within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> and the cause of the disconnection determined and evaluated for generic implications.

Snubbers are classified and grouped by design and manufacturer but not by size.

For example, mechanical snubbers utilizing the same design features of the 2-kip, 10-kip, and 100-kip capacity manufactured by Company "A" are of the same type.

The same design mechanical snubbers manufactured by Company "B" for the Chapter 16.9-13 Page 6 of 11 04/22/99

. l BASES (cont'd)

O purposes of this Commitment would be of a different type, as would hydraulic snubbers from either manufacturer.  !

A list of individual snubbers with detailed information of snubber location and size and of system affected shall be available at the plant in accordance with Section 50.71(c) of 10 CFR Part 50. The addition or deletions of any hydraulic or -

mechanical snubber shall be made in accordance with Section 50.59 of 10 CFR Part 50.

The visual inspection frequency is based upon maintaining a constant level of l snubber protection during an earthquake or severe transient. Therefore, the required inspection interval varies inversely with the observed snubber failures and is determined by the number of inoperable snubbers found during an inspection. In order to establish the inspection frequency for each type of snubber, it was assumed that the frequency of snubber failures and initiating events are constant with time and that the failure of any snubber on that system could cause the system to be unprotected and to result in failure during an assumed initiating event. 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 25%) may not be used to lengthen the required inspection interval. Any inspection Q whose results require a shorter inspection interval will override the previous schedule. The acceptance criteria are to be used in the visualinspection to determine OPERABILITY of the snubbers.

To provide assurance of snubber functional reliability, one of three functional testing methods are used with the stated acceptance criteria:

1. Functionally test 10% of a type of snubber with an additional 10% tested for each functional testing failure, or

2. Functionally test a sample size and determine sample acceptance using Figure 16.9-13A, or

3. Functionally test a representative sample size and determine sample acceptance or rejection using the stated equation.

Figure 16.9-13A was developed using "Wald's Sequential Probability Ratio Plan" as described in " Quality Control and Industrial Statistics" by Acheson J. Duncan.

Permanent or other exemptions from the inspection program for individual snubbers may be granted by the Commission if a justifiable basis for exemption is presented and, if applicable, snubber life testing was performed to qualify the snubber for the O

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BASES (cont'd)

O' applicable design conditions. Snubbers so exempted shall be listed in the list of individual snubbers indicating the extent of the exemptions.

The service life of a snubber is established via manufacturer input and information through consideration of the snubber service conditions and associated installation and maintenance records (newly installed snubbers, seal replaced, spring replaced, in high radiation area, in high temperature area, etc.).

The requirement to monitor the snubber service life is included to ensure that the snubbers periodically undergo a performance evaluation in view of their age and operating conditions. These records will provide statistical bases for future consideration of snubber service life.

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t TABLE 16.9-13A

! SNUBBER VISUAL INSPECTION INTERVAL l

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NUMBER OF UNACCEPTABLE SNUBBERS Population Column A Column B Column C or Category Extend Interval Repeat Interval Reduce Interval (Notes 1 and 2) (Notes 3 and 6) (Notes 4 and 6) (Notes 5 and 6)

! 0 1 0 1 l l 80 0 0 2 l 100 0 1 4 150 0 3 8 200 2 5 13 300 5 12 25 400 8 18 36 500- 12 24 48 750 20 40 78 O 'ooo or sraater 29 Se 109 Note 1: The next visual inspection interval for a snubber population or category l

size shall be determined based upon the previous inspection interval and the number of unacceptable snubbers found during that interval.

Snubbers may be categorized, based upon their accessibility during power operation, as. accessible or inaccessible. These categories may be examined separately orjointly. However, the licensee must make and document that decision before any inspection and shall use that decision as the basis upon which to determine the next inspection interval for that category.

Note 2: Interpolation between population or category sizes and the number of unacceptable snubbers is permissible. Use next lower integer for the value of the limit for Columns A, B, or C if that integer includes a fractional value of unacceptable snubbers as determined by l Interpolation.

l Note 3: If the number of unacceptable snubbers is equal to or less than the number in Column A, the next inspection interval may be twice the previous interval but not greater than 48 months.

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, , TABLE 16.9-13A (Continued)

SNUBBER VISUAL INSPECTION INTERVAL Note 4: If the number of unacceptable snubbers is equal to or less than the numberin Column B but greater than the number in Column A, the next inspection interval shall be the same as the previous interval.

Note 5: If the number of unacceptable snubbers is equal to or greater than the number in Column C, the next inspection interval shall be two-thirds of the previous interval. However, if the number of unacceptable snubbers is less than the number in Column C but greater than the number in Column B, the next interval shall be reduced proportionally by interpolation, that is, the previous interval shall be reduced by a factor that is one-third of the ratio of the difference between the number of unacceptable snubbers found during the previous interval and the number in Column B to the difference in the numbers in Columns B a'nd C.

Note 6: The provisions of SLC 16.2.6 are applicable for all inspection intervals l up to and including 48 months.

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8 7

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1 C 5 4 -

j CONTINUE i TESTING l 3 '

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ACCEPT 1 r J

0 10 20 30 40 50 60 70 80 90 100 N

FIGURE 16.9-13A SAMPLE PLAN 2) FOR SNUBBER FUNCTIONAL TEST O

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