ML20058N017
| ML20058N017 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 09/27/1993 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20058N009 | List: |
| References | |
| NUDOCS 9310070284 | |
| Download: ML20058N017 (3) | |
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, fg UNITED STATES i i9M[iE NUCLEAR REGULATORY COMMISSION (gg5' j
WASHINGTON, D.C. 20555-0001 yoj SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO.150 TO FACitITY OPERATING LICENSE NO. NPF-6 ENTERGY OPERATIONS. INC..
ARKANSAS NUCLEAR ONE. UNIT NO. 2 DOCKET N0. 50-368
1.0 INTRODUCTION
By letter dated May 7, 1993, Entergy Operations, Inc. (the licensee) submitted a request for changes to the Arkansas Nuclear One, Unit No. 2 (ANO-2)
Technical Specifications (TSs).
The requested changes would reduce the maximum allowable linear power level-high trip setpoints associated with inoperable steam line safety valves listed in TS Table 3.7-1 and revise the associated Bases.
l 2.0 BACKGR0'.IND i
AN0-2 has five main steam line code safety valves on each main steam header and there are two main steam headers.
The main steam line code safety valves ensure that secondary system pressure will be limited to less than 110% of design pressure (as allowed by the ASME Code), during the most severe, anticipated operational transient.
To prevent main steam pressure from exceeding 110% of design pressure under these conditions, these valves must be capable of discharging all of the steam energy produced by the steam generators.
If one or more of these valves is inoperable, reactor power needs to be adjusted to prevent the steam produced from exceeding the degraded steam relief crpacity.
Currently, TS Table 3.7-1 requires the linear power level-high trip setpoint be reduced to:
99.5% when one main steam line code safety valve is inoperable on any operating steam generator, 74.0% when two are inoperable, and 48.6%
when three are inoperable.
The licensee states that the values were j
calculated in accordance with Standard Technical Specifications (NUREG-0212) l assuming a maximum steam relief capacity of 125% of the steam generated at i
100% powed.
In the May 7, 1993 application, the licensee states that the actual maximum steam relief capacity of the valves is 116.5% of the steam generated at 100%
power.
Since the actual steam relief capacity of the valves is less than that assumed when the original specification was developed, an amendment is necessary to ensure that the maximum allowable pressure is not exceeded during anticipated operational transients when the steam relief capacity is degraded.
9310070284 930927 PDR ADOCK 05000368 P
i The new linear power level-high trip setpoints proposed by the licensee are 91.0%, 67.7%, and 45.0%.
3.0 EVALUATION In its application, the licensee provided a calculation to support the new J
linear power level-high trip setpoints.
The NRC staff has reviewed the calculation and the proposed Bases change (the Bases outlines the calculation).
The full power (100%) steam flowrate is increased by 2% for conservatism and divided by 2 to obtain the flowrate per steam line.
- Next, the total rated flowrate in the steam line (the sum of the rated flowrates of the five individual valves) is divided by the modified full power (100%) steam flowrate discussed above.
The result of this division is about 114%.
- Then, i
to account for degraded relief capacity, the 114% is multiplied by the ratio of the operable rated flowrate in the degraded steam line (sum of the rated i
flowrates of the operable valves) to the total rated flowrate in the steam line.
This computation is repeated for 1, 2 or 3 inoperable valves, assuming that the valves with the highest rated flowrate become inoperable first. The results of this computation (91.0%, 67.7% and 45.0%) are the new allowed reactor power levels assuming 1, 2 and 3 inoperable safety valves.
Operation with more than 3 inoperable valves is not allowed per TSs.
The NRC staff has reviewed the calculation and finds that the ratio of the available rated relieving capacity to the total steam flowrate at 100% power
(+ 2% for conservatism), which is about 114%, is an appropriate correction to the 125% value assumed previously. The staff also finds that, by assuming the inoperable valves with the highest flowrate become inoperable first, the calculation is sufficiently conservative. Accordingly, the staff finds that the proposed TSs and Bases are acceptable.
4.0 STATE CONSULTATION
In accordance with the Commission's regulations, the Arkansas State official was notified of the proposed issuance of the amendment. The State official had no comments.
5.0 ENVIRONMENTAL CONSIDERATION
The amendment changes a requirement with respect to installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20. 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 (58 FR 34074). Accordingly, the amendment meets 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 amendment.
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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:
T. Alexion, PDIV-1 Date: September 27, 1993 l
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