ML20238F296
| ML20238F296 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 08/28/1998 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20238F294 | List: |
| References | |
| NUDOCS 9809030255 | |
| Download: ML20238F296 (4) | |
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7 A
9 000 k
UNITED STATES
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NUCLEAR REGULATORY COMMISSION 2
WASHINGTON, D.C. 20066 4 001 o
.....g SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 235 TO FACILITY OPERATING LICENSE NO. DPR-77 AND AMENDMENT NO. 225 TO FACILITY OPERATING LICENSE NO. DPR-79 TENNESSEE VALLEY AUTHORITY SEQUOYAH NUCLEAR PLANT. UNITS 1 AND 2 DOCKET NOS. 50-327 AND 50-328
1.0 INTRODUCTION
The Tennessee Valley Authority (WA, the licensee) requested amendments to Operating Licenses DPR-77 and DPR-79 for Sequoyah Nuclear Plant (SON), Units 1 and 2, respectively, in a letter to the U.S. Nuclear Regulatory Commission (NRC) dated February 13,1998. The amendments would revise the SON Units 1 and 2 Technical Specifications (TSs) by relocating the mechanical snubber requirements from Section 3.7.9 of the TS, and its bases, to the SON Technical Requirements Manual (TRM). This change does not alter the requirements for operability or surveillance testing of the snubbers. This amendment also deletes License Condition 2.C.(19), for Unit 1 only. This condition is a one-time snubber-related action that was completed and no longer needs to be included in the SON Operating License.
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2.0 BACKGROUND
WA re' quested the proposed change to remove requirements from the SON TSs that do not meet the criteria in 10 CFR 50.36 for specifications that are required to be contained in the TSs.
In the Commission's Final Policy Statement on Technical Specifications improvements for Nuclear Power Reactors, published in the Federal Reaister. Page 39132, Volume 58, Number 139, the NRC stated that TSs that do not meet any of the screening criteria for retention may be proposed for removal from the TSs and relocated to licensee-controlled documents, such as the Final Safety Analysis Report or TRM. This change will allow revisions to the snubber requirements in accordance with 10 CFR 50.59 without requiring a license amendment request and adds flexibility to processing necessary changes.
The License Condition deletion for Unit 1 is proposed to remove requirements from the SON License that are no longer necessary. The License Condition states the following:
l Within 12 months after issuance of the license, WA shall provide a Technical i
Specification listing of mechanical snubbers. In the interim, WA will conduct a comprehensive mechanical snubber inspection program implemented by plant instructions.
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l 3.0 EVALUATION j
i Snubbers are active devices used for supporting piping system transients, such as water
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hammer, pipe failure, or a seismic event. The restraining action of the snubbers ensures that l
the initiating event failure does not propagate to other parts of the failed system or to other safety systems.' Snubbers also allow normal thermal expansion of piping and nozzles to eliminate excessive thermal stresses during startup and shutdown.
The current SQN TSs requirements provide actions for inoperability and surveillance to verify the operability of safety-related snubbers. The current action for an inoperable snubber is to replace or return the snubber to operable status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> and perform an engineering evaluation of the attached component. The attached system is declared inoperable if the 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> expires or the evaluation indicates that the system is inoperable. The current surveillance provide requirements for an augmented inservice inspection program including visual and functional tests. This specification also contains program allowances for inspection interval, lot size, inspection evaluation, lot composition, acceptance criteria, failure analysis, attached component analysis, service life, and exceptions from visual or functional tests.
Current TS Bases discussions contain the basis for requiring snubbers,'the basis for the allowed snubber outage time, and clarifications regarding the application of the snubber surveillance requirements.
The proposed changes are consistent with the Westinghouse plant improved Standard TSs (NUREG-1431) and 10 CFR 50.36. NUREG-1431 does not include requirements for verification of snubber operability and the criteria in 10 CFR 50.36 for features required to be retained in TSs do not apply to the SON snubbers, as discussed below. NRC's Final Policy Statement recommends that TSs that do not meet the screening criteria for retention may be relocated to a licensee-controlled document. The following discussions address the applicability to the 10 CFR 50.36 criteria:
Criterion 1: Installed instrumentation that is used to detect, and indicate in the control room, a significant abnormal degradation of the reactor coolant pressure boundary.
l The snubbers are not installed instrumentation nor do they have the ability to detect abnormal degradation of the reactor coolant pressure boundary. Therefore, the SON safety-related snubbers do not satisfy Criterion 1.
Criterion 2: A process variable, design feature, or operating restriction that is an initial L
condition of a Design Basis Accident (DBA) or Transient that either assumes, the failure l
of or presents a challenge to the integrity of a fission product barrier.
The snubbers are a design feature that is associated with maintaining the integrity of safety-related piping systems during accident transients. However, the snubbers are not explicitly considered in the accident analysis and are not considered a required initial condition for a DBA 4
or Transient to maintain the integrity of a fission product barrier. The availability of the l
snubbers is assured based on the performance of periodic inspections and testing. Therefore, the SQN snubbers do not satisfy Criterion 2.
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Criterion 3: A structure, system, or component that is part of the primary success path and which functions or actuates to mitigate a DBA or Transient that either assumes the failure of or presents a challenge to the integrity of a fission product barrier.
Safety-related snubbers are design features thst function during accidents or transients to prevent the propagation of an event to systems that are part of the primary success path for accident mitigation. However, snubbers are not explicitly considered in the accident analysis, but are a structural design feature whose operation is assured by an inspection program. The SQN snubbers are not a primary success path for accident mitigation; therefore, they do not satisfy Criterion 3.
Criterion 4: A structure, system, or component, which operating experience or probabilistic safety assessment has shown to be significant to public health and safety.
Operational experience or probabilistic safety assessment have not shown the SON snubbers to be significant to the public health and safety. Therefore, the snubbers do not satisfy -
Criterion 4.
The proposed relocation of the snubber requirements to the SQN TRM is acceptable based of the above discussions. The TRM has been incorporated into the Final Safety Analysis Report by reference and the relocated requirements will be controlled in accordance with 10 CFR 50.5g to ensure changes are not implemented that would reduce the functionality or testing of l
the snubbers without prior NRC review. TVA has approved the SQN TRM, which includes l
these requirements for the snubbers.
l The deletion of License Condition 2.C.(19) for Unit 1 is an editorial change that will hot impact the function of SON safety-related features. The action to provide a listing of mechanical snubbers and an interim inspection program was satisfied previously such that this condition is no longer applicable to SQN and the current requirements for safe operation. The snubber listing was added to the SQN Unit 1 TSs in August 1981 but was later removed by Amendment No. 39, dated June 20,1985 in response to NRC Generic Letter 84-13.
4.0 STATE CONSULTATION
in accordance with the Commission's regulations, the Tennessee State official was notified of the proposed issuance of the amendments. The State official had no comments.
5.0 ENVIRONMENTAL CONSIDERATION
The amendment changes a requirement with respect to installation or use of a facility 4
component located within the restricted area as defined in 10 CFR Part 20 and changes surveillance requirements. The NRC staff has determined that the amendment involves no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure. The Commission has previously issued a proposed finding that the amendment involves no significant hazards consideration, and there has been no public comment on such finding (63 FR 17235, dated April 8,1998). Accordingly, the L
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4 amendments meet the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9). Pursuant to 10 CFR 51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendments.
6.0 CONCLUSION
The Commission has concluded, based on the considerations discussed above, that: (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributor: Ronald W. Hernan Dated: August 28, 1998 I
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