ML20205Q732
| ML20205Q732 | |
| Person / Time | |
|---|---|
| Site: | South Texas  |
| Issue date: | 04/16/1999 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20205Q724 | List: |
| References | |
| NUDOCS 9904220041 | |
| Download: ML20205Q732 (3) | |
Text
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o ner UNITED STATES g
j NUCLEAR REGULATORY COMMISSION o
2 WASHINGTON, D.C. 20066 4001 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NOS.106 AND 93 TO FACILITY OPERATING LICENSE NOS. NPF-76 AND NPF-80 STP NUCLEAR OPERATING COMPANY DOCKET NOS. 50-498 AND 50-499 SOUTH TEXAS PROJECT. UNITS 1 AND 2 i
1.0 INTRODUCTION
By application dated January 26,1999, STP Nuclear Operating Company, et al. (the licensee),
requested changes to the Technical Specifications for the South Texas Project (STP), Units 1 and 2. The proposed changes would revise the inspection requirements for its reactor coolant pump (RCP) flywheels. This issue was addressed in the Westinghouse Topical Report, WCAP-14535, " Topical Report on Reactor Coolant Pump Flywheel Inspection Elimination,"
which was approved by the staff with certain conditions. These conditions are specified in the safety evaluation report (SER) dated September 12,1996, for WCAP-14535. The licensee intended to apply this topical report to its STP, Units 1 and 2, and change the RCP flywheels inspection intervals in accordance veith the conclusion of the SER on WCAP-14535.
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2.0 BACKGROUND
The function of the RCP in the reactor coolant system (RCS) of a pressurized water reactor (PWR) is to maintain an adequate cooling flow rate by circulating a large volume of primary coolant water at high temperature and pressure through the RCS. A concern over overspeed of the RCP and its potential for failure led to the issuance of Regulatory Guide (RG) 1.14 in 1971. Since then, all licensees for PWR plants, with very few exceptions, have adopted the guidelines of RG 1.14 to conduct their RCP flywheel examinations. These requirements are normally specified in the individual plant's TS as is the case for STP.
' 3.0 EVALUATION in the SER on Westinghouse Topical Report WCAP-14535, the staff stated that the evaluation methodology for RCP flywheels in WCAP-14535 is appropriate and the criteria are in accordance with the design criteria of RG 1.14. In addition, the staff specified:
(1) Ucensees who plan to submit a plant-specific application of this topical report for flywheels made of SA 533 8 material need to confirm that their flywheels are made of SA 533 B material. Further, licensees having Group-15 flywheels need to demonstrate that the material properties of their A516 material are equivaient to SA 533 B material, and its reference temperature, RTuoy, is less than 30'F.
ENCLOSURE 9904220041 990416 PDR ADOCK 05000498 P
o 4
2-(2) Licensees who plan to submit a plant-specific application of this topical report for their flywheels not made of SA 533 B or A516 material need to either demonstrate that their flywheel material properties are bounded by those of SA 533 B material, or provide the minimum specif:ed ultimate tensile stress, S, the fracture o
toughness, K, and the reference temperature, RT
, for that material. For the latter, the licensees should employ these material specific properties, and use the methodology in the topical report, as extended in the two responses to the staff's request for additional information, to provide an assessment to justify a change in inspection schedules for their plants.
(1) Licensees meeting either (1) or (2) above should either conduct a qualified in-place ultrasonic testing (UT) examination of the volume from the inner bore of the flywheel to the circle of one-half the outer radius or conduct a surface examination (MT and/or PT) of exposed surfaces defined by the volume of the disassembled flywheels once every 10 years. The staff considers this 10-year inspection requirement not burdensome when the flywheel inspection is conducted during scheduled Inservice Inspection or RCP motor maintenance. This woulo provide an appropriate level of defense in depth.
Further, the staff required:
Licensees with Group-10 flywheels need to confirm in the near term that their flywheels have an adequate shrink fit of the flywheel at the maximum overspeed.
The licensee confirmed in its submittal that the flywheels for STP, Units 1 and 2, are made of SA 533 B material. Hence, only (1) and (3) apply. The staff further verified that the flywheels for STP, Units 1 and 2, do not belong to either Group 10 or Group 15 flywheels, for which additional analyses need to be performed. Therefore, the plant-specific applicability of WCAP-14535 to STP, Units 1 and 2, has been established, and the 10-year inspection requirement with details specified in (3) is acceptable. Hence, the staff accepts the licensee's proposed changes to Surveillance Requirement 4.4.10 for both units.
4.0 STATE CONSULTATION
In accordance with the Commission's regulations, the Texas State official was notified of the proposed issuance of the amendments. The State official had no comments.
5.0 ENVIRONMENTAL CONSIDERATION
The amendments change surveillance requirements. The NRC staff has determined that the amendments involve 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 amendments involve no significant hazards consideration, and there has been no public comment on such finding (64 FR 11968, March 10,1999).
Accordingly, the amendments meet the eligibility criteria for categorical exclusion set forth in i
s
! 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 issucnce 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 amendments will not be inimical to the common defense and security or to the health and safety of the public.
1 Principal Contributor: S.Sheng Date: April 16, 1999 4
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