ML20058E268
| ML20058E268 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 11/01/1990 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20058E261 | List: |
| References | |
| NUDOCS 9011070101 | |
| Download: ML20058E268 (3) | |
Text
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO.110 TO FACILITY OPERATING LICENSE NO. NPF-6 ENTERGY OPERATIONS. INC.
ARKANSAS NUCLEAR ONE. UNIT NO. 2 DOCKET NO. 50-368 INTRODUCTION By letter dated August 22, 1989, as supplemented July 5, 1990, Arkansas Power and Light Company requested changes to the Technical Specifications (TSs) appended to Facility Operating License No. NPF-6 for Arkansas Nuclear One, Unit No.2(ANO-2). The proposed amendment would change the allowable minimum setpoint value on the Pressurizer Code Safety Valves as listed in TSs 3.4.2 and 3.4.3, and would change the allowable minimum setpoint range value on the Main Steam Line Code Safety Valves as listed in TS Table 3.7-5.
The change would specify an operability range for the safety) valves from -3% to +1% of the required setpoint.
(Previously it was 11%.
If the "as found" setpoint exceeded the 11% band, then adjustment of the setpoint to within the t1% band would be required. A change would also be made to the corresponding Bases section.
In addition, the licensee, in a letter dated July 2, 1990, requested a change to the TS Bases Section 3/4.3.3.3 to correct a reference included therein.
EVALUATION The Code of Federal Regulations, 10.CFR 50.55a, requires, in part, that certain safety valves be tested in accordance with the American Society of Mechanical Engineers (ASME)Section XI Code requirements.
The current Technical Specifications 3.4.2 and 3.4.3 require that the Pressurizer Code Safety Valves have a lift setpoint of 2500f plus or minus 1%.
Technical Specification Table 3.7-5 requires that the main steam line safety valves have a lift setpoint as specified within a range of from plus to minus 1%. When a surveillance identifies drift in the "as found" setpoints outside the TS-limits for any of these code safety valves, ASME Code Section XI requires resetting, repair, or replacement of the valve and further requires that additional valves in the system be tested.
In addition, the licensee is required to submit a Licensee Event Report in accordance with 10 CFR 50.73 whenever the TS requirements have not been met.
The-licensee, in its submittal, indicated that the specified tolerance for these valves is occasionally exceeded during surveillance testing, usually in the minus direction and results in the additional testing of other valves, beyond 9011070101 901101 PDR ADOCK 05000360 ?
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e that normally required. This results in an impact on plant schedule and additional radiation exposure to plant staff performing the tests. The ASME has recognized the potential for code safety valves to experience setpoint drift; i.e., ASME/ ANSI OM-1987 requires that a valve be repaired or replaced and the cause of failure be determined and corrected only if the valve exceeds its set pressure by 3% or greater. Thus the staff feels that the licensee's proposed change in the specified operability range of from -3% to +1% of the specific setpoint is not inconsistent with available ASME Code guidance.
Further, in the licensee's design basis analyses, the pressurizer code safety valves and the main steam line safety valves both were assumed to open at a
' pressure 1% above the setpoint. Hence, if the valves lifted at a setpoint less than this analyzed value, then the resultant peak pressure would be bounded by the limiting case established by the plus 1% tolerance. The licensee also performed an analysis of the minus 3% tolerance and determined that there would be no impact on the system response results derived by the original analyses.
The licensee did determine, however, that for one postulated event, the steam generator tube rupture, with a loss of offsite power, the offsite dose could increase by ar much as 10% above previous estimates, but the result would still remain withia 10 CFR Part 100 limits and would be below the estimated offsite doses cairdlated for the bounding case of a Loss of Coolant Accident. The licensee indicated that the increased dose would be caused by the increased release of steam through the main steam line code safety valves associated with the affected steam generator prior to its isolation.
Following the isolation, only steam from the intact steam generator would be released and this steam would have a lower assumed concentration of radioactive material.
The staff has reviewed the licensee's justification for the proposed TS revision as discussed above and has determined that this revision indicates a change in the definition of operability of the valves but not in the design basis requirement to have the setpoints maintained within plus or minus 1%. This TS revision of the pressurizer code safety valve and main steam line code safety setpoint tolerance, as requested, would have acceptably low safety significance and would not exceed the. limits of any of the accident analyses. Therefore, this rrvision is considered acceptable.
The staff has also reviewed the licensee's proposed change to the ANO-2 TS Basis 3/4.3.3.3tocorrectthereferenceforRegulatoryGuide(RG)1.12
" Instrumentation for Earthquakes." The current TS Basis lists the date of the RG as April 1974. The proposed modification changes the date to March 1971, which is the revision date of the RG cited in the ANO-2 Safety Analysis Report -
and-more significantly, the plant was designed in accordance with the 1971 revision of the RG. Therefore, the staff finds this change to TS Basis 3/4.3.3.3 to be acceptable.
ENVIRONMENTAL CONSIDERATION The amendment involves a change in a requirement with respect to the installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and changes in surveillance requirements. The
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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 exposures. 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.
Accordingly, the amendment meets the eligibility) criteria for categorical exclusionsetforthin10CFRSection51.22(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 emendment.
CONCLUSION
'The staff has concluded, based on the considerations discussed above, that:
(1) there is reasonable assurance that the health and safety of the will not be endangered by operation in the proposed manner, and (2) public such activities will be conducted in compliance with the Commission's regulations, and the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.
Dated:
November 1, 1990 Principal Contributor: Chester Posiusny, Jr.
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