ML18038B186
| ML18038B186 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 03/09/1995 |
| From: | Salas P TENNESSEE VALLEY AUTHORITY |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| TAC-M89249, TAC-M89250, NUDOCS 9503140145 | |
| Download: ML18038B186 (26) | |
Text
PR.IC3R.I EY' ACCELERATED RIDS PROCESSING REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)
ACCESSION NBR: 9503140145 DOC. DATE: 95/03/09 NOTARIZED: NO DOCKET FACIL:50-260 Browns Ferry Nuclear Power Station, Unit 2, Tennessee 05000260 50-296 Browns Ferry Nuclear Power Station, Unit 3, Tennessee 05000296 AUTH. NAME AUTHOR AFFILIATION SALAS,P. Tennessee Valley Authority RECIP.NAME RECIPIENT AFFILIATION Document Control Branch (Document Control Desk)
SUBJECT:
Provides addi info for NRC review of 940330 submittal of TS 318,re qualification of Agastat relays used in analog transmitter/trip sys,per 950119 request.
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I Tennessee Valley Authority, Post Office Box 2000, Decatur, Alabama 35609 March*9, 1995 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555 Gentlemen:
In the Matter of Docket Nos. 50-260 Tennessee Valley Authority 50-296 BROWNS FERRY NUCLEAR PLANT (BFN) - SUPPLEMENTAL INFORMATION ON TECHNICAL SPECIFICATION (TS) 318 - ANALOG TRANSMITTER/TRIP SYSTEM (ATTS)~ LEVEL 1 REACTOR WATER LEVEL SETPOINTSg AND VARIOUS CALIBRATION FREQUENCIES (TAC NOS ~ M89249 AND M89250)
This letter provides additional information for the NRC staff's review of the subject proposed TS amendment. TS 318 was originally submitted for staff review by letter, dated March 30, 1994. In a January 19, 1995 letter, the staff requested TVA provide additional information regarding TS 318 and the qualification of the Agastat relays used in the ATTS.
The enclosure to this letter contains a response to the staff's request.
In summary, the Agastat output relays in the Unit 2 ATTS, and proposed for the Unit 3 ATTS, are safety related and are located in a mild environment. The Staff has requested TVA justify the qualified lifetimeand of these relays and the surveillance testing to adequacy of the qualification identify aging-related failures. The overall issue regarding the level of qualification for equipment important to safety and located in a mild environment has been thoroughly addressed as part of the development of the final rule on environmental qualification of electric equipment important to safety (10 CFR 50.49).
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U.S. Nuclear Regulatory Commission Page 2 March 9, 1995 As part of that rulemaking, the Staff determined that environmental qualification (including the determination of a qualified lifetime) was not required and that the current quality assurance requirements were sufficient to ensure adequate performance of this equipment. The qualification testing performed on these relays is above and beyond the requirements for mild environment equipment and is sufficient for TVA's use in determining an expected service life for the Agastat relays. TVA has not identified any instances of Agastat relay failures in the ATTS during its review of BFN equipment failure databases. The service life of these relays will be adjusted, as necessary, as a result of the current program for trending equipment failures. TVA is also unaware of any regulatory requirements for TS surveillance testing to identify aging-related failures. Incipient age related failures of Agastat relays would be detected by the current trending program prior to the occurrence of concurrent failures that could defeat redundancy.
In addition, the generic review and NRC approval of the specific installation of the ATTS is documented in Licensing Topical Report NEDO-21617-A. TVA's installation of the ATTS meets or exceeds these requirements.
There are no commitments contained in this letter. If you have any questions, please contact me at (205) 729-2636.
Sincerel Pe o Salas Manager of Site Licensing Enclosure cc: see page 3
,t U.S. Nuclear Regulatory Commission Page 3 March 9, 1995 cc (Enclosure):
Mr. Mark S. Lesser, Acting Branch Chief U.S. Nuclear Regulatory Commission Region 101 II Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323 NRC Resident Inspector Browns Ferry Nuclear Plant Route 12, Box 637 Athens, Alabama 35611 Mr. J. F. Williams, Project Manager U.S. Nuclear Regulatory Commission One White Flint, North 11555 Rockville Pike Rockville, Maryland 20852
ENCLOSURE TENNESSEE VALLEY AUTHORITY BROWNS FERRY NUCLEAR PLANT (BFN)
UNITS 1 q 2 AND 3 TECHNZCAL SPECZFICATZON (TS) 3 18 ANALOG TRANSMITTER/TRIP SYSTEM@
LEVEL 1 REACTOR WATER LEVEL SETPOZNTS AND VAR1OUS CALIBRATION FREQUENCIES BACKGROUND OF TS 318 TS 318 was originally submitted for staff review by letter, dated March 30, 1994. The proposed change:
- 1. Reflected the installation of an Analog Transmitter/Trip System (ATTS) on Unit 3, which is similar to the system previously installed on Unit 2.
- 2. Revised the Units 1 and 3 Reactor Vessel Water Level Safety Limit to reflect the analytical limit provided by General Electric. In addition, the Level 1 Low Reactor Vessel Water Level setpoint was revised to provide a more conservative limit. These changes were previously approved for the Unit 2 TSs.
- 3. Added or corrected Unit 2 instrument identifiers to enhance the useability of the TSs.
- 4. Revised calibration frequencies and functional test descriptions for the Unit 2 Reactor High Water Level, Reactor Core Isolation Cooling (RCIC) and High Pressure Coolant Injection (HPCI) Turbine Steam Line High Flow, and Drywell Pressure instrument. channels.
- 5. Revised the calibration frequency for the differential pressure instrumentation, which actuates the pressure suppression chamber-reactor building vacuum breakers, in the Units 1, 2, and 3 TSs to reflect current calculations. In addition, tables that specify the minimum number of instrument channels per trip system, function, trip level setting, actions required, remarks, functional test, and instrument check were added.
U.S. Nuclear Regulatory Commission Page 4 March 9, 1995 JEM: SMK: MTN cc (Enclosure):
P. P. Carier, BR 4G-C E. S. Christenbury, ET 11H-K K. N. Harris, LP 3B-C R. W. Huston, Rockville Office-C R. D. Machon, PAB 1E-BFN J. P. Maciejewski, LP 3B-C T. J. McGrath, LP 3B-C T. W. Overlid, BR 4J-C E. Preston, POB 2C-BFN
. C. M. Root, CFC 1D-BFN (w/o Enclosures)
T. D. Shriver, PAB 1A-BFN H. L. Williams, EDB 1A-BFN ~
RIMS, WT 3B-K n Atechspectts-318.smk
- 6. Corrected the capitalization of terms used on the affected Units 1, 2, and 3 TS pages in order to conform with the current TS Definitions section. This part also corrected spelling and capitalization of other words on the same pages.
The staff requested additional information regarding TS 318 in a September 21, 1994 letter to TVA'. A response to each of the staff's requests was provided by TVA on November 18, 1994 . From November 28 through December 2, 1994, the NRC technical reviewer for this proposed TS change conducted a review of calculations and supporting documentation at the BFN site. After subsequent investigation of industry experience by the NRC's technical reviewer, the NRC requested additional information regarding TS 318 and the qualification of the Agastat relays used in the ATTS on January 19, 19953,.
The Agastat output relays in the Unit 2 ATTS, and proposed for the Unit 3 ATTS, are safety related and are located in a mild environment; As discussed below, the overall issue regarding the level of qualification for equipment important to safety and located in a mild environment has been thoroughly addressed as part of the development of the final rule on environmental qualification of electric equipment important to safety (10 CFR 50.49). TVA's conformance to these requirements and its program for safety related equipment located in a mild environment, including the Agastat relays, are also discussed.
REQUIREMENTS FOR EQUIPMENT IMPORTANT TO SAFETY LOCATED IN A MILD ENVIRONMENT The Agastat output relays used in the Unit 2 ATTS and proposed for the Unit 3 ATTS, are safety related and located in a mild environment. As with the vast majority of components, both safety related and non-safety related, random failures of these components are expected to occur, be detected and corrected during the life of the plant. The requirements for nuclear power plant equipment important to safety being able to perform their safety functions is embodied in General Design Criteria 1, 2, 4, and 23 of Appendix A, "General Design Criteria for Nuclear Power Plants," to 10 CFR Part 50. The nuclear industry and NRC have used a variety of methods to ensure that these general requirements are met for electric equipment important to safety.
Prior to 1971, qualification was based on the fact that the electrical components were of high industrial quality.
NRC letter to TVA dated Scptcmbcr 21, 1994, Rctlucst for Additional Information - TS 318 TVA letter to NRC, dated Novcmbcr 18, 1994, Supplcmcntal Information on Technical Spccilication gS) No. 318 - Analog Transmitterffrip System, Lcvcl 1 Reactor Water Lcvcl Sctpoints, and Various Calibration Fretlucneics s
NRC lcttcr to TVA, dated January 19, 1995, Request for Additional Information E-2
During the late 1970s, the NRC undertook a program to reevaluate the qualification of electric equipment in operating nuclear power plants. As a part of this program, more definitive criteria for environmental qualification of electric equipment important to safety was developed by NRC. A document entitled "Guidelines for Evaluating Environmental Qualification of Class 1E Electrical Equipment in Operating Reactors" (Division of Operating Reactor Guidelines) was issued in November 19794.
Section 7.0 of the DOR Guidelines regarding aging states that, "Implicit in the staff position in Regulatory Guide 1.89 with regard to backfitting IEEE Std. 323-1974 is the staff's conclusion that the incremental improvement in safety from arbitrarily requiring that a specific qualified life be to demonstrated for all Class lE equipment is not sufficient justify the expense for plants alreadyexclude constructed and operating.
equipment using This position does not, however, material that have been identified as being susceptible to significant'degradation due to thermal and radiation aging.
Component maintenance or replacement schedules should include considerations of the specific aging characteristics of the component materials. Ongoing programs should exist at the plant to review surveillance and maintenance records to assure that equipment which is exhibiting age-related degradation will be identified and replaced as necessary."
By its Memorandum and Order CLI-80-21, dated May 23, 1980, the Commission directed the staff to proceed with a rulemaking on environmental qualification of safety-related equipment and to address the question of backfit. As a result, on January 20, 1982, NRC published in the Federal Register a notice
.of proposed rulemaking on environmental qualification of electric equipment for nuclear power plants . The proposed rule made no distinction between equipment located in a harsh or mild environment. It was during this timeframe that environmental qualification tests were performed of the Agastat relays (Models ETR and EGP) currently in use at BFN, since to it appeared that located'n a mild electric equipment important safety and environment might require formal qualification if the proposed rule was not revised in this regard.
In response to the proposed rule, the Nuclear Utility Group on Equipment Qualification, which consisted of 21 utilities, provided comments on the proposed rule6 on March 25, 1982. As noted therein, other regulatory approaches besides "qualification" are designed to assure equipment operability Thc DQR Guidclincs were included as an enclosure to IE Bulletin 79%1B, Environmental Qualilication of Class 1E Equipmcnt, dated January 14, 1980 47 FR2876 Letter from thc Nuclear Utility Group on Equipment Qualification to NRC, dated March 25, 1982, Regarding Notice of Proposed Rulcmaking Regarding Environmental Qualilication of Electric Equipment for Nuclear Power Plants (47 Fcd. Rcg. 2876 January 20, 1982)
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(i.e., the single failure criterion and the concepts of redundance, diversity, independence, testability and defense-in-depth). In addition, other NRC rules assure appropriate control of activities which may affect the performance of such equipment. Further, licensee actions to assure equipment operability include extensive quality assurance measures, component and system pre-operability checks and tests, operating experience reviews, preventive maintenance, surveillance and in-service inspections and operability checks.
Thus, "qualification" is not the only method, or even the most significant method, of providing assurance of equipment operability. Accordingly, the Nuclear Utility Group on Equipment Qualification requested the Staff's concepts and applications reflected in the proposed rule be reconsidered and integrated with other industry practices and other Commission regulations.
With specific regards to the qualification of equipment located in a mild environment, the Nuclear Utility Group on Equipment Qualification stated that the concept of qualification was used historically by both the nuclear power industry and NRC to not provide a degree of assurance that common mode failures will occur during accident conditions which impose significant additional stresses not present during normal operation or during surveillance testing. Qualification can serve the necessary significant accident stresses that are not present during normal operation or surveillance testing (such as equipment in containment) is not vulnerable to such accident stress conditions during the period of its needed operation. Qualification need not be required for that class of equipment which is exposed to accident stresses that are not significantly different from those present during normal operation or surveillance testing.
Consequently, the Nuclear Utility Group on Equipment Qualification requested the proposed rule be modified to apply different requirements to equipment located in harsh and mild environments and the Staff recognize that for equipment located in mild environments, adequate assurance of operability is achieved through the use of continuing activities such as operating experience reviews, preventive maintenance, surveillance and periodic testing techniques.
On April 20, 1982, in Generic Letter 82-09~, the Staff responded to a number of technical questions from licensees and clarified certain aspects of the proposed qualification requirements. In this letter the Staff stated that equipment environmental qualification for existing equipment located in mild environments could be demonstrated and maintained by the use of the following three programs:
- 1. A periodic maintenance, inspection, and/or replacement program based on sound engineering practice and NRC letter to All Power Reactor Liccnsccs, Applicants for an Operating License, NSSS Vendors and Reactor Vendors, dated April 20, 1982, Environmental Qualification of Safety-Related Electrical Equipment (Generic Lcttcr 8249)
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recommendations of the equipment manufacture which is updated as required by the results of an equipment surveillance program; 2 A periodic testing program to verify operability of safety-related equipment within its performance
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specification requirements (system level testing of the type typically required by the plant technical specifications may be used); and 3 ~ An equipment surveillance program which includes periodic inspections, analysis of equipment and component failures, and a review of the results of preventive maintenance and periodic testing programs.
It should be noted that the Agastat relays in the Unit 2 ATTS are currently covered by programs that satisfy these requirements.
Specifically, TVA is currently committed to either replace the Agastat relays in the ATTS after 20 years of service or document the acceptability of a longer service life. This service life is based upon a laboratory test report that documents acceptable performance for these relays under design environmental conditions equivalent to 20 years of service at 24'C (754F), 95 percent relative humidity, 2 x 10'ads, and 27,500 mechanical cycles. The relays were also subjected to a seismic test that bounds the BFN seismic spectra. TVA has evaluated Agastat's recommended replacement schedule and industry reports of Agastat relay failures. The 20-year service life of the Agastat relays will be modified, as required, as discussed in Item 3, below.
2 ~ Surveillance testing is performed on the Unit 2 ATTS in accordance with the frequencies specified in the BFN Unit 2 TSs (i.e., the majority of instrument channels are tested monthly or quarterly with the maximum period of 18 months).
3 ~ Site Standard Practice 6.4, Equipment History and Failure Trendin'g, establishes the requirements and processes for collecting equipment maintenance history, trending equipment reliability, as well as maintenance identifying repetitive and generic history data bases.
failure trends from the The final rule on environmental qualification of electric equipment important to safety (10 CFR 50.49) was published on January 21, 1983. Safety related electrical equipment that is required to remain functional during and following a design basis E-5
accident and is located in a harsh environment is required to be environmentally qualified. The qualification program for this equipment must include and be based:
- l. on the time dependent temperature and pressure at the location of the equipment for the most severe design basis accident for which this equipment is required,
- 2. humidity present during the design basis accident, 3 ~ chemical effects of the most severe environment,
- 4. radiation dose, including the total does expected during the normal life of the component. plus the radiation environment associated with the most severe design basis accident,
- 5. preconditioning of the equipment by natural or artificial aging. The equipment must be replaced or refurbished at the end of this designated life unless an ongoing qualification program demonstrates additional life,
- 6. submergence, if required,
- 7. synergic effects, and
- 8. margin.
The final rule did not cover the electric equipment locatedwith in a mild environment. The supplementary information provided the final rule stated that "The Commission has concluded that the general quality and surveillance requirement applicable to electric equipment as a result of other Commission regulations, including 10 CFR 50, Appendix B (see for example, Regulatory Guide 1.33, "Qualify Assurance Program Requirements (Operation)."
Revision 3) are sufficient to ensure adequate performance of electric equipment important to safety located in mild environments. Since it has been concluded that no further environmental qualification requirements are needed for such equipment provided they fully satisfy all other applicable regulations, the Commission has determined that no additional requirements are necessary."
As a result of the final rule, the environmental qualificat'ion testing of the Agastat relays and the determination of a qualified life is not required since they are located in a mild environment. Thus, the qualification testing performed on these relays is above and beyond the requirements for mild environment equipment and is sufficient for TVA's use in determining an expected service life for"the Agastat relays. In addition, the programs discussed in Generic Letter 82-09 for demonstrating and maintaining the equipment environmental qualification for existing equipment located in mild environments are also not required. The general quality and surveillance requirements, which the NRC has stated are sufficient to ensure adequate performance of electric equipment important to safety located in E-6
mild environments, are specified in TVA's Nuclear Quality Assurance Plan.
The historical purpose of equipment qualification is summarized in the Electric Power Research Institute (EPRI) Equipment Qualification Reference Manual . It states that: "One aspect of defense-in-depth is a tolerance for single, randomly occurring failures provided by designed-in redundancy of safety related systems. Qualification aims at eliminating "common cause" failures (Systematic, nonrandom, concurrent failures). that can defeat redundancy by incapacitating the two or more paths or trains available for providing essential safety functions."
SPECIFIC NRC REQUESTS AND TVArS RESPONSES NRC REQUEST TVA is requested to provide the following information regarding Agastat relays used in the Browns Ferry Nuclear Plant ATTS:
- 1. Demonstrate the effectiveness of relay surveillance testing to fully exercise relay capability and detect aging-related failures.
TVA RESPONSE The safety function of the Agastat relays in use in the Unit 2 ATTS is to change state (i.e., from an energized condition to a de-energized condition or vise versa). The change of state allow electrical contacts to open ori close in order to provide the necessary logic function for the process variable input. Typical connection and functional block diagrams are shown on the attached figure.
The calibration and testing techniques used for the ATTS are addressed in NEDO-21617-A . In the NRC review'f this Topical Report, the Staff stated that repeat its review of this topical report it "does not intend to when it appears as a reference in specific license applications, except to assure that the report is applicable to the specific plants involved. Should regulatory criteria or regulations change such that our conclusions concerning this topical report are invalidated, you will be notified and will be given the opportunity to revise and resubmit your topical report for review, should you so desire." With specific regards to the NRC lcttcr to All Power Reactor Liccnsccs, Applicants for an Operating License, NSSS Vendors and Reactor Vendors, dated April 20, 1982, Environmental Qualification of Safety-Rclatcd Electrical Equipment (Generic Lcttcr 8249)
NEDO-21617-1, Analog TransmittcrfI'rip Unit System for Engineered Safeguard Sensor Trip Inputs, Dcccmbcr 1978 NRC lcncr to General Electric Coinpany, dated Junc 27, 1978, Rcvicw of Gcncral Electric Topical Rcport NEDO-21617, Analog Transmitterffrip Unit System for Engincercd Safeguard Sensor Trip Input" E-7
surveillance testing techniques, the Staff states, "The testing advantages for this equipment are significant. The only demerit in this method is that the transmitter itself is not tested as frequently. However, the likelihood of an undetected failure of the transmitter is minimized by the ability to compare the output of one transmitter to identical divisional transmitter output at any time".
the'ther With specific regards to the application of these techniques at BFN, each ATTS instrument channel listed in the BFN TSs that contains an Agastat relay is periodically demonstrated to be operable by the performance of a surveillance instruction. In some cases, the energizing or de-energizing of the Agastat relay is specifically checked and included in the acceptance criteria for the surveillance instruction.
Failure of the relay to change state'would result in the channel being declared inOperable and a maintenance request being issued to replace the relay. Even when the actual change of state of the relay is not verified, the failure of the instrument channel to produce a trip signal when subjected to a simulated input signal would also result in the channel being declared inoperable and a maintenance request being issued to determine the cause of the failure.
Maintenance would identify an Agastat relay that would not change state and would replace the relay.
TVA has not identified any instances of Agastat relay failures in the ATTS during its review. of BFN equipment failure databases. As previously discussed, random failures of Agastat relays are expected to occur, be detected and corrected during the remaining life of the plant. Site Standard Practice 6.4, Equipment History and Failure Trending, establishes the requirements and processes for collecting equipment maintenance history, trending equipment reliability, as well as identifying repetitive and generic failure trends from the maintenance history data bases.
Aging related failures would either be identified as part of the root cause investigation of an individual relay failure or through the identification of a trend of increasingly frequent failures of the same type, of relay.
TVA is also unaware of any regulatory requirements for TS surveillance testing to identify aging-related failures.
Incipient age related failures of Agastat relays would be detected by this trending program prior to the occurrence of concurrent failures that could defeat redundancy by incapacitating the two or more paths or trains available for providing essential safety functions. It should also be noted that normally energized relays would be expected to fail in the safe condition (i.e., in the tripped condition) and the Standby Liquid Control System is also designed to make the reactor subcritical from rated power to a cold shutdown at any time in core life with the control rods remaining withdrawn in the rated power pattern.
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NRC REQUEST 2 ~ Justify a qualified relay lifetime of 20 years in light of relatively recent vendor recommendations which suggest a much shorter qualified lifetime, or propose a different qualified lifetime, including appropriate justifications.
TVA RESPONSE With specific regard to the relays used in ATTS, the qualification tests and associated margins and conformance to applicable IEEE standards and Regulatory Guides are addressed in NEDO-21617-A. In the NRC review of this Topical Report, with specific regards to the area of equipment qualification, the Staff states that "the qualification of the equipment to the requirements of IEEE 323-1974 is part of the generic review of the qualification program for all Class IE equipment in GESSAR scope. Therefore, the acceptability of this equipment for newer plants will be based on the outcome of this generic review."
The information required to be provided by each applicant that uses Topical Report NEDO-21617-A as licensing basis is listed in Section 5.4. With specific regards to the environmental interface, Section 5.4.3 states the environment at each location where the retrofit hardware will be located must be compared toThis the maximum environment as stated in the topical report. comparison was provided by TVA as part of the original submittal of TS 318 for staff review on March 30, 1994.
As discussed above, the generic review and subsequent rulemaking resulted in requirements for the establishment of a qualified life for equipment important to safety that is located in a harsh environment, not for the Agastat relays used by BFN in a mild environment. Thus, the qualification tests previously reviewed by TVA do not represent regulatory required documentation, but rather provided supplemental information for TVA to determine expected service life. The documentation of industry events cited by the Staff do not provide the level of detail (i.e., normal operating or previously experience peak transient temperatures inside the relay cabinets) that would be necessary for TVA to establish an accurate comparison of the Agastat relay service life at these facilities versus that which can be expected at BFN.
TVA has not identified any instances of Agastat relay failures in the ATTS during its review of BFN equipment failure databases. As previously discussed, random failures of safety related equipment that is located in a mild environment, including Agastat relays, are expected to occur, be detected and corrected during the remaining life of the plant. TVA will continue to monitor industry events in accordance with its Nuclear Experience Review Program and trend any failure of BFN's Agastat relays in accordance with II E-9
Site Standard Practice 6.4 and adjust the service life of the relays as appropriate.
NRC REQUEST
- 3. Justify the ability of Agastat relay qualification testing referenced by TVA to adequately address the following failure mechanisms:
- a. Off-gas coating and oxidation of relay contacts, and
- b. Bobbin failures caused by internal heating, resulting in restricted armature movement.
TVA RESPONSE As previously discussed, the qualification tests previously reviewed by TVA do not represent regulatory required documentation, but rather provided supplemental information for TVA to determine expected service life. The qualification tests on the Agastat. relays were performed in accordance with IEEE 323-1974. IEEE 323-1974 was endorsed by the Staff as an adequate methodology for determining the qualification of electrical equipment important to safety and located in a harsh environment in the supplementary information provided with the publication of the final rule for the environmental qualification of electric equipment important to safety. Regulatory Guide'1.89'lso states that: "The procedures described by IEEE Std 323-1974 are acceptable to the NRC staff for satisfying the Commission's regulations pertaining to the qualification of electric equipment for service in nuclear power plants In summary, the Agastat output relays in the Unit 2 ATTS and proposed for Unit 3 are safety related and are located in a mild environment. The overall issue regarding the level of qualification for equipment important to safety and located in a mild environment has been thoroughly addressed as part of the development of the final rule on environmental qualification of electric equipment important to safety (10 CFR 50.49). As part of that rulemaking, the Staff determined that environmental qualification (including the determination of a qualified lifetime) was not required and that the current quality assurance requirements were sufficient to ensure adequate performance of this equipment. The qualification testing performed on these relays is above and beyond the requirements for mild environment equipment and is sufficient for TVA's use in determining an expected service life for the Agastat relays. TVA has not identified any instances of Agastat relay failures in the ATTS during its review of BFN equipment failure databases. The Regulatory Guide 1.89, Environmental Qualification of Certain Electric Eiiuipment Important to Safety for Nuclear Power Plants, Revision 1, dated Junc 1984
1 service life of these relays will be adjusted, as necessary, as a result of the current program for trending equipment failures.
TVA is also unaware of any regulatory requirements for TS surveillance testing to identify aging-related failures.
Incipient age related failures of Agastat relays would be detected by the current trending program prior to the occurrence of concurrent failures that could defeat redundancy.
The generic review and NRC approval of the specific installation of the ATTS is documented in Licensing Topical Report NEDO-21617-A. TVA's proposed installation of the ATTS on Unit 3 meets or exceeds these requirements.
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