ML060260191

American Society of Mechanical Engineers (ASME)Section XI Code Relief Request - Snubber Examination and Testing

ML060260191
Person / Time
Site:	Sequoyah
Issue date:	01/25/2006
From:	Pace P Tennessee Valley Authority
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
Download: ML060260191 (15)

Text

January 25, 2006 10 CFR 50.55a U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555 Gentlemen:

In the Matter of )

Docket Nos. 50-327 Tennessee Valley Authority )

50-328 SEQUOYAH NUCLEAR PLANT (SQN) - AMERICAN SOCIETY OF MECHANICAL ENGINEERS (ASME) SECTION XI CODE RELIEF REQUEST -

SNUBBER EXAMINATION AND TESTING Enclosed is a request for relief from ASME Section XI Code.

TVAs relief request proposes to perform snubber examination and testing in accordance with the SQN Technical Requirements Manual (TRM) as an alternative to the ASME Section XI Code requirements. The proposed request for relief is a continuation of the previously approved relief request from SQNs second 10-year inspection interval and is being submitted for applicability during SQNs third 10-year inspection interval that is scheduled to begin on June 1, 2006.

TVA has reviewed snubber examination and functional test requirements as contained in the ASME Section XI Code and has compared the code requirements with SQNs snubber examination and test program as contained in the SQN TRM.

Based on this review, TVA concludes that ASME code requirements would introduce redundant requirements to SQNs TRM snubber inspection and test program and in some cases result in confusion created by differences in snubber grouping. These differences potentially lead to misinterpretation when selecting test samples, applying acceptance criteria, corrective action, and examination schedules for failed snubbers. Accordingly, pursuant to 10 CFR 50.55a(a)(3)(i), TVA is requesting relief from ASME Section XI Code requirements for snubbers.

U.S. Nuclear Regulatory Commission Page 2 January 25, 2006 provides the proposed request for relief and provides a copy of SQNs TRM snubber inspection and test program.

Please direct questions concerning this issue to me at (423) 843-7170 or J. D. Smith at (423) 843-6672.

Sincerely, Original signed by James D. Smith for:

P. L. Pace Manager, Site Licensing and Industry Affairs Enclosures cc (Enclosures):

Mr. Douglas V. Pickett, Senior Project Manager U.S. Nuclear Regulatory Commission Mail Stop O-8G9a One White Flint North 11555 Rockville Pike Rockville, Maryland 20852-2739

E1-1 ENCLOSURE 1 Sequoyah Nuclear Plant Units 1 and 2 SNUBBER RELIEF REQUEST Components:

American Society of Mechanical Engineers (ASME),Section XI Code Class 1, 2, and 3, Snubbers.

Code Requirements:

ASME Boiler and Pressure Vessel Code,Section XI, 2001 Edition, 2003 Addenda, Subarticles:

IWA-4530(b), Preservice Inspection and Testing IWF-5200(a) and (b), Preservice Examinations and Tests IWF-5300(a) and (b), Inservice Examinations and Tests IWF-5400, Repair/Replacement Activities IWA-6210(c), Records and Reports IWA-6230, Summary Report Preparation IWA-6240, Summary Report Submittal IWA-2100, Examination and Inspection IWA-4530(b), IWF-5200(a) and (b), IWF-5300(a) and (b), and IWF-5400 requirements provide the methodology and corrective actions for examination and functional testing of snubbers.

IWA-6210(c), IWA-6230, and IWA-6240 require inservice inspection summary reports for Class 1 and 2 snubbers be prepared and filed with the regulatory authority. IWA-2100 requires Authorized Nuclear Inservice Inspector (ANII) involvement for snubber examination and testing.

Code Requirement From Which Relief Is Requested:

In accordance with 10 CFR 50.55a(a)(3)(i), relief is requested from the ASME Boiler and Pressure Vessel Code,Section XI, 2001 Edition, 2003 Addenda, requirements for preservice and inservice examinations and tests of snubbers:

E1-2 IWA-4530(b) requires preservice inspection and testing to be in accordance with IWF-5200 following repair/replacement of a snubber.

IWF-5200(a) and (b) requires preservice examinations and tests in accordance with ASME/ANSI OM Part 4, 1987 Edition, OMa-1988 Addenda, using the VT-3 visual examination method in accordance with IWA-2213.

IWF-5300(a) and (b) requires inservice examinations and tests in accordance with ASME/ANSI OM Part 4, 1987 Edition, OMa-1988 Addenda, using the VT-3 visual examination method in accordance with IWA-2213.

IWF-5400 references IWF-5200 for snubber examination and test requirements.

IWA-6210(c) requires the preparation of preservice and inservice inspection summary reports for Class 1 and 2 snubbers.

IWA-6230 requires the preparation of an inservice inspection summary report after each refueling outage.

IWA-6240 requires the submittal of summary reports to the regulatory authority.

IWA-2100 requires Authorized Nuclear Inservice Inspector (ANII) involvement for snubber examination and testing.

As an alternative to the above code requirements, TVA proposes to perform examination and testing of snubbers in accordance with the SQN Technical Requirements Manual (TRM).

Basis for Relief:

Sequoyah Nuclear Plants (SQN) Units 1 and 2 are required to update to the 2001 Edition, 2003 Addenda, of the ASME Section XI Code for SQNs third 10-year snubber test and inspection interval. The code requirements contain snubber inspection and testing methodologies that are nearly identical to the methodologies prescribed in SQNs TRM for examination and testing of snubbers. Compliance with ASME code would introduce a redundant set of snubber requirements and present unnecessary confusion in sample selection, data collection, acceptance criteria, and corrective actions. Additional confusion is created by the difference in snubber grouping.

E1-3 ASME Section XI addresses Class 1, 2, 3, and Metal Containment (MC) component supports while the SQN TRM addresses all safety-related snubbers which include Class 1, 2, 3, and MC component supports. Approximately half of the snubbers at SQN would be required to be tested in accordance with ASME Section XI, while the other half would be tested in accordance with the TRM. Introducing two nearly redundant sets of snubber requirements present unnecessary confusion in sample selection, snubber grouping, data collection, acceptance criteria, and corrective actions. Accordingly, the administration of overlapping programs and criteria to the varied population of snubbers becomes difficult to apply.

One programmatic area that should be noted is the snubber examination schedules. Examination schedules that are in SQNs TRM snubber program adopt the provisions provided in NRC Generic Letter (GL) 90-09, "Alternative Requirements for Snubber Visual Inspection Intervals and Corrective Actions."

The purpose of the GL was to provide alternative guidance to snubber inspection schedules that were excessively restrictive. The alternative schedule was to alleviate the expenditure of unnecessary resources and prevent radiological exposure associated with the over restrictive examination schedules. The implementation of ASME/ANSI OM Part 4, 1987 Edition, OMa-1988 Addenda, would return the examination schedule for approximately half of the snubbers in SQNs snubber examination program to the frequency which existed prior to the publication of GL 90-09. This would essentially cancel the relaxation provided by GL 90-09.

Alternate Examination and Test:

SQN will perform examination and testing of snubbers as required by SQN TRM (TR 3/4.7.9, "Snubbers). SQN will continue to submit reports of any adverse conditions for snubbers in accordance with TVAs Corrective Action Program.

Justification For The Granting Of Relief:

The current snubber program for SQN is defined by the TRM (TR 3/4.7.9) and provides for a level of quality and safety equal to or greater than the ASME code. The ASME code provides for failure mode grouping of snubbers that fail visual examination, meaning only those snubbers identified as being in that group would require shortened examination intervals. Under SQNs TRM snubber program, all snubbers in the population would be placed in a shortened inspection interval. On this basis, SQNs TRM snubber program is more

E1-4 conservative in corrective action than the ASME code. As previously discussed, administering different criteria to a varied population of snubbers can create confusion while selecting test samples, applying acceptance criteria, corrective action, and examination schedules for failed snubbers. This situation could increase the possibility of applying the wrong action, thus creating a nonconformance, an inoperability, or even a violation of the TRM.

In order to eliminate any misinterpretation or confusion in administering requirements for snubbers, and to remove the possibility of applying contradicting requirements to the same snubber(s), TVA proposes to examine and test snubbers in accordance with SQNs TRM (TR 3/4.7.9). The SQN TRM for testing and examination of snubbers provides an equal or greater level of quality and safety than the ASME Code.

Because relief is sought from the ASME Section XI snubber examination and test requirements, TVA does not plan to include a third party for ASME Section XI snubber examination or test activities. The ASME code would require Authorized Nuclear Inservice Inspector (ANII) involvement. The SQN TRM snubber program does not require (ANII) involvement for examination and test requirements. The SQN TRM snubber program is directed by a designated snubber program engineer.

The snubber program engineer provides oversight of the TRM snubber program during implementation. Included in the oversight are responsibilities for serving as the TRM test director in accordance with TVAs procedure for conducting a test, and for reviewing the TRM examination and test data.

By reviewing and evaluating the TRM examination and test data, the snubber program engineer provides an acceptable level of quality and safety without third party inspector participation. ANII involvement for snubber repair and replacement activities is maintained as required by TVAs ASME Section XI Repair and Replacement Program.

Because relief is sought from the ASME Section XI requirements for the preparation and submittal of summary reports for snubber examinations and tests, TVA does not plan to prepare snubber summary reports for submittal to NRC. The SQN TRM is implemented by site procedures (surveillance instructions) that retain inspection and test results for snubbers. On-site retention of the snubber inspection and test results in a summary report format is considered acceptable for recording this data. Performance of each test or inspection is documented and retained with the site procedure as a summary report with data similar to the requirements prescribed in the ASME Section XI Code.

E1-5 ASME Section XI VT-3 certification required by personnel performing snubber visual examinations is an additional certification as compared to the SQN TRM snubber program training qualifications. Personnel performing the TRM visual examinations are trained specifically on the TRM implementing instructions prior to performing the examinations. Training and documentation of personnel to the visual acceptance criteria, specifically in the TRM implementing instructions, provides an acceptable level of quality and safety. TVA does not plan to require VT-3 certification. In lieu of VT-3 certification, TVA plans to implement visual requirements that meet ASME Section XI, 2001 Edition, 2003 Addenda, Paragraph IWA-2321(a), Visual Acuity, for inspection personnel.

==

Conclusion:==

Based on the above justification, SQN's examination and testing of snubbers in accordance with the SQN TRM 3/4.7.9 will provide an acceptable level of quality and safety.

Therefore, pursuant to 10 CFR 50.55a(a)(3)(i), it is requested that relief be granted.

TVAs request for relief is applicable to SQNs third 10-year interval and is a continuation of SQNs relief request previously approved in NRC Safety Evaluation Report dated May 16, 1996 (TAC NOS M93947 and M93948).

E2-1 ENCLOSURE 2 Sequoyah Nuclear Plant Units 1 and 2 TECHNICAL REQUIREMENTS MANUAL (TRM)

E2-2 TR 3/4.7 PLANT SYSTEMS TR 3/4.7.9 SNUBBERS LIMITING CONDITION FOR OPERATION TR 3.7.9. All safety-related snubbers shall be OPERABLE.

APPLICABILITY: MODES 1, 2, 3, and 4. (MODES 5 and 6 for snubbers located on systems or partial systems required OPERABLE in those MODES.)

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 on the attached component or declare the attached system inoperable and follow the appropriate Technical Specification ACTION statement for that system.

SURVEILLANCE REQUIREMENTS TR 4.7.9. Each safety-related snubber shall be demonstrated OPERABLE by performance of the following augmented inservice inspection program and the requirements of Technical Requirement 4.0.5.

a.

Inspection Groups The snubbers may be categorized into two major groups based on whether the snubbers are accessible or inaccessible during reactor operation. These major groups may be further subdivided into subgroups based on design, environment, or other features which may be expected to affect the OPERABILITY of the snubbers within the subgroup. Each subgroup may be tested independently in accordance with TR 4.7.9.d through TR 4.7.9.h.

b.

Visual Inspection Schedule and Lot Size All of the safety-related snubbers shall be included in one population, or they shall be categorized as accessible or inaccessible for visual inspection. If used, the accessible or inaccessible categories shall be considered separately for visual inspections.

When recombining categories into one population, the shorter interval of the categories shall be used.

The visual inspection interval for the population or each category shall be determined based upon the criteria provided in Table 4.7.9-1., 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 the amendment which incorporated this change was issued by the NRC.

SEQUOYAH - UNITS 1 AND 2 3/4 7-5 October 1, 1998 TECHNICAL REQUIREMENTS Revision Nos. 1

E2-3 Table 4.7.9-1 SNUBBER VISUAL INSPECTION INTERVAL NUMBER OF UNACCEPTABLE SNUBBERS Population Column A Column B Column C or Category Extended Interval Repeat Interval Reduce Interval (Notes 1 and 2) (Notes 3 and 6) (Notes 4 and 6) (Notes 5 and 6) 1 0 0 1 80 0 0 2 100 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 1000 or greater 29 56 109 Note 1: The next visual inspection interval for a snubber population or category 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 or jointly. 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 size 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 described by interpolation.

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.

Note 4:

If the number of unacceptable snubbers is equal to or less than the number in 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 and C.

Note 6:

The provisions of Technical Requirement 4.0.2 are applicable for all inspection intervals up to and including 48 months.

SEQUOYAH - UNITS 1 AND 2 3/4 7-6 October 1, 1998 TECHNICAL REQUIREMENTS Revision Nos. 1

E2-4 PLANT SYSTEMS SURVEILLANCE REQUIREMENTS (Continued)

c.

Visual Inspection Performance and Evaluation Visual inspections shall verify (1) that there are no visible indications of damage or impaired OPERABILITY, (2) bolts attaching the snubber to the foundation or supporting structure are secure, and (3) snubbers attached to sections of safety-related systems that have experienced unexpected potentially damaging transients since the last inspection period shall be evaluated for the possibility of concealed damage and functionally tested, if applicable, to confirm operability.

Snubbers which appear inoperable as a result of visual inspections may be determined OPERABLE for the purpose of establishing the next visual inspection interval, providing that (1) the cause of the rejection is clearly established and remedied for that particular snubber and for other snubbers that may be generically susceptible and (2) the affected snubber is functionally tested in the as-found condition and determined OPERABLE per TR 4.7.9.e. Hydraulic snubbers with inoperable single or common fluid reservoirs which have uncovered fluid ports shall be declared inoperable.

Also, snubbers which have been made inoperable as the result of unexpected transients, isolated damage, or other such random events, when the provisions of TR 4.7.9.g and TR 4.7.9.h have been met and any other appropriate corrective action implemented, shall not be counted in determining the next visual inspection interval.

d.

Functional Test Schedule, Lot Size, and Composition At an interval commensurate with each refueling outage, a representative sample of 10% of the total of the safety-related snubbers in use in the plant shall be functionally tested either in place or in a bench test. The representative sample selected for functional testing shall include the various configurations, operating environments, and the range of size and capacity of snubbers within the groups or subgroups. The representative sample should be weighted to include more snubbers from severe service areas such as near heavy equipment. Unless a failure analysis as required by TR 4.7.9.f indicates otherwise, the sample shall be a composite based on the ratio of each group to the total number of snubbers installed in the plant. Snubbers placed in the same location as snubbers which failed the previous functional test shall be included in the next test lot if the failure analysis shows that failure was due to location.

The security of fasteners for attachment of the snubbers to the component and to the snubber anchorage shall be verified on snubbers selected for functional tests.

The provisions of Technical Requirement 4.0.2 are applicable to the interval for performing functional tests. During plant operating MODES 1 through 4 (and MODES 5 and 6 for snubbers located on systems or partial systems required OPERABLE in those MODES), administrative controls are required for performing snubber functional surveillance testing for the purpose of satisfying the functional test interval requirement.

SEQUOYAH - UNITS 1 AND 2 3/4 7-7 October 1, 1998 TECHNICAL REQUIREMENTS Revision Nos. 1

E2-5 PLANT SYSTEMS SURVEILLANCE REQUIREMENTS (Continued)

e.

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

1.

Activation (restraining action) is achieved within the 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 where required, is present in both tension and compression within the specified range.

3.

The force required to initiate or maintain motion of the snubber is within the specified range in both directions of travel.

4.

For snubbers specifically required not to displace under continuous load, the ability of the snubber to withstand load without displace-ment shall be verified.

5.

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.

f.

Functional Test Failure Analysis and Additional Test Lots If any snubber selected for functional testing either fails to lock up or fails to move due to manufacture or design deficiency, all snubbers of the same design subject to the same defect shall be functionally tested. If more than two snubbers do not meet the functional test acceptance criteria, an additional lot equal to one-half the original lot size shall be functionally tested for each failed snubber in excess of the two allowed failures. An engineering evaluation shall be made of each failure to meet the functional test acceptance criteria to determine the cause of the failure. The result of this analysis shall be used, if applicable, in selecting snubbers to be tested in the subsequent lot in an effort to determine the operability of other snubbers which may be subject to the same failure mode. (Selection of snubbers for future testing may also be based on the failure analysis.) Testing shall continue until not more than one additional inoperable snubber is found within a subsequent required lot or all snubbers of the original inspection group have been tested, or all suspect snubbers identified by the failure analysis have been tested, as applicable.

The discovery of loose or missing attachment fasteners will be evaluated to determine whether the cause may be localized or generic. The result of the evaluation will be used to select other suspect snubbers for verifying the attachment fasteners, as applicable.

Snubbers shall not be subjected to prior maintenance specifically for the purpose of meeting functional test requirements.

SEQUOYAH - UNITS 1 AND 2 3/4 7-8 October 1, 1998 TECHNICAL REQUIREMENTS Revision Nos. 1

E2-6 PLANT SYSTEMS SURVEILLANCE REQUIREMENTS (Continued)

g.

Functional Test Failure - Attached Component Analysis For snubber(s) found inoperable, an engineering evaluation shall be performed on the components which are restrained by the snubber(s). The purpose of this engineering evaluation shall be to determine if the components restrained by the snubber(s) were adversely affected by the inoperability of the snubber(s) and in order to ensure that the restrained component remains capable of meeting the designed service.

h.

Functional Testing of Repaired and Spare Snubbers Snubbers which fail 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.

These snubbers shall have met the acceptance criteria subsequent to their most recent service, and the functional test must have been performed within 12 months before being installed in the unit.

i.

Snubber Service Life Program The service life of hydraulic and mechanical snubbers shall be monitored to ensure that the service life is not exceeded between surveillance inspections. The maximum expected service life for the various seals, springs, and other critical parts shall be determined and established based on engineering information and shall be extended or shortened based on monitored test results and failure history. Critical parts shall be replaced so that the maximum service life will not be exceeded during a period when the snubber is required to be OPERABLE. The parts replacements shall be documented, and the documentation shall be retained in accordance with Appendix B, Table 2, of the Nuclear Quality Assurance Plan.

j.

Exemption From Visual Inspection or Functional Tests Permanent or other exemptions from the surveillance program for individual snubbers may be granted by the Commission if a justifiable basis for exemption is presented and if applicable snubber life destructive testing was performed to qualify snubber operability for the applicable design conditions at either the completion of their fabrication or at a subsequent date.

SEQUOYAH - UNITS 1 AND 2 3/4 7-9 October 1, 1998 TECHNICAL REQUIREMENTS Revision Nos. 1

E2-7 TRB 3/4.7 PLANT SYSTEMS BASES TRB 3/4.7.9 SNUBBERS Snubbers are designed to prevent unrestrained pipe or component motion under dynamic loads as might occur during an earthquake or severe transient, while allowing normal thermal motion during startup and shutdown. The con-sequence of an inoperable snubber is an increase in the probability of structural damage to piping or components as a result of a seismic or other event initiating dynamic loads. It is therefore required that all snubbers required to protect the primary coolant system or any other safety system or component be operable during reactor operation.

Because the snubber protection is required only during relatively low probability 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 to replace or restore the inoperable snubber(s) to operable status and perform an engineering evaluation on the supported component or declare the supported system inoperable and follow the appropriate limiting condition for operation statement for that system. The engineering evaluation is performed to determine whether the mode of failure of the snubber has adversely affected any safety-related component or system. Individual snubbers may be removed from service for functional testing during plant operating MODES 1 through 4 (and MODES 5 and 6 for snubbers located on systems or partial systems required OPERABLE in those MODES) provided administrative controls established herein are met.

Safety-related snubbers are visually inspected for overall integrity and operability. The inspection will include verification of proper orientation, adequate fluid level if applicable, and attachment of the snubber to its anchorage. The removal of insulation or the verification of torque values for threaded fasteners is not required for visual inspections.

The inspection frequency is based upon maintaining a constant level of snubber 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 25 percent) may not be used to lengthen the required inspection interval. Any inspection whose results require a shorter inspection interval will override the previous s schedule.

When the cause of the rejection of a snubber in a visual inspection is clearly established and remedied for that snubber and for any other snubbers that may be generically susceptible and operability verified by inservice functional testing, if applicable, that snubber may be exempted from being counted as inoperable. Generically susceptible snubbers are those which are of a specific make or model and have the same design features directly related to rejection of the snubber, or are similarly located or exposed to the same environmental conditions such as temperature, radiation, and vibration. Test groups may be established based on design features and installed conditions which may be expected to be generic. Each of these groups are tested separately unless an engineering analysis indicates the group is improperly constituted. All suspect snubbers are subject to inspection and testing regardless of test groupings.

SEQUOYAH - UNITS 1 AND 2 B 3/4 7-4 October 1, 1998 TECHNICAL REQUIREMENTS Revision Nos. 1

E2-8 PLANT SYSTEMS BASES SNUBBERS (Continued)

To further increase the assurance of snubber reliability, functional tests shall be performed at an interval commensurate with each refueling outage. These tests will include stroking of the snubbers to verify proper movement, activation, and bleed or release. The performance of hydraulic snubbers generally depends on a clean, deaerated fluid contained within variable pressure chambers, flowing at closely controlled rates. Since these characteristics are subject to change with exposure to the reactor environment, time, and other factors, their performance within the specified range should be verified.

Mechanical snubbers which depend upon overcoming the inertia of a mass and the braking action of a capstan spring contained within the snubber for limiting the acceleration of the attached component (within the load rating of the snubber) are not subject to changes in performance in the same manner as hydraulic snubbers. Pending the development of information regarding the change during the service of the snubber of the acceleration/resistance relationship and the optimum method for detecting this change, these mechanical snubbers may be tested to verify that when subjected to a large change in velocity the resistance to movement increases greatly. The performance change information was developed in order to establish test methods to be used during and after the first refueling outage.

Ten percent of the total population of snubbers is an adequate sample for functional tests. The initial sample is to be proportioned among the groups in order to obtain a representative sample. Observed failures of more than two snubbers in the initial lot will require an engineering analysis and testing of additional snubbers selected from snubbers likely to have the same defect. A thorough inspection of the snubber threaded attachments to the pipe or components and the anchorage will be made in conjunction with all required functional tests.

Snubbers may be removed from service for functional surveillance testing in MODES 1 through 4 (and MODES 5 and 6 for snubbers located on systems or partial systems required OPERABLE in those MODES) to satisfy the required testing interval, provided the following administrative controls are implemented:

1. TR 3.7.9 ACTION statement shall be met

2. Snubbers on trained systems or portions of trained systems may be removed only on the scheduled train work week. Snubbers on non-trained systems or portions on non-trained systems may only be removed following a documented risk assessment. Snubbers may not be removed from service for testing on one train of a system while the other train has been declared inoperable for any reason.

3. No more than one snubber may be removed from service at a time on any line and attached piping which is analyzed as a seismic subsystem.

Multiple snubbers may be removed for testing simultaneously only if separated by a seismic anchor.

A list of individual snubbers with detailed information of snubber location and size shall be available at the plant in accordance with Section 50.71(c) of 10 CFR Part 50. The accessibility of each snubber shall be determined based upon the existing radiation levels and the expected time to perform a visual inspection in each snubber location as well as other factors associated with accessibility during plant operations (e.g., temperature, atmosphere, location, etc.), and the recommendations of Regulatory Guide 8.8 and 8.10. The addition or deletion of any hydraulic or mechanical snubber shall be made in accordance with Section 50.59 of 10 CFR Part 50.

SEQUOYAH - UNITS 1 AND 2 B 3/4 7-5 October 1, 1998 TECHNICAL REQUIREMENTS Revision Nos. 1