ML15112A855
| ML15112A855 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 03/19/1979 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML15112A854 | List: |
| References | |
| NUDOCS 7904060078 | |
| Download: ML15112A855 (3) | |
Text
SRUNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT NO. 71 TO FACILITY OPERATING LICENSE NO. DPR-38 AMENDMENT NO. 71 TO FACILITY OPERATING LICENSE NO. DPR-47 AMENDMENT NO. 68 TO FACILITY OPERATING LICENSE NO. DPR-55 DUKE POWER COMPANY OCONEE NUCLEAR STATION, UNITS NOS. 1, 2 AND 3 DOCKETS NOS. 50-269, 50-270 AND 50-287 Introduction By letter dated February 21, 1978, Duke Power Company (DPC) requested revisions to the Oconee Nuclear Station, Units Nos. 1, 2 and 3 Technical Specifications to incorporate changes to the Oconee Unit No. 1 pressuri zation heatup and cooldown limitations. None of the atypical weld material that was reported as possibly being used in the Oconee Unit No.
3 reactor vessel welds was reported for the Oconee Unit No. 1 reactor vessel.
Discussion/Evaluation By letter dated February 21, 1978, DPC submitted a proposed amendment to Technical Specification 3.1.2 for Oconee Unit 1 revising the pressure temperature operating limits. The new limits were proposed for operation through 8 effective full power years (EFPY). They were based on the results of tests on Capsule OCI-E specimens recently removed from Oconee Unit 1.
These test results are reported in the Babcock and Wilcox Report, BAW-1436, September.1977. Copies of this report were enclosed in DPC's February 21, 1978 letter for NRC review.
We have reviewed the BAW-1436 report. Data shows that weld metal is the limiting material.
The weld metal in Capsule OCI-E is identified as Procedure Qualification (PQ) number )F-112. At a fluence of 1.5 x 1018 n/cm2 it showed an increase in RTNDTkl) of 1240F. This report also includes fluence calculations based on data from dosimeters removed from the reactor vessel with Capsule OCI-E. The maximum fluence (E 7 1 mev) on the vessel wall at the one-quarter thickness (1/4T) location after 10 EFPY is calculated to be 3.2 x 1018 m/cm2.
We conclude that the mechanical properties data and the fluence values reported are acceptable.
790406007 (1)RTNDT is the symbol for reference temperature. The reference temperature is the greater of the nil ductility temperature or 600F less than the temperature at which 50 ft-lbs Charpy energy exists in a given material.
-2 In a letter dated August 31, 1977, DPC submitted information to NRC on Oconee Unit 1 reactor vessel materials. This letter lists six different weld metals used in the vessel beltline region: WF-25, SA-1073, SA-1135, SA-1229, SA-1430, SA-1493, and SA-1585. All of these welds are estimated to receive the maximum fluence on the vessel wall.
Also, we note that the surveillance weld, WF-112, is not identical to any of these welds; i.e., it was not made from the same weld wire and flux. Therefore, it is prudent to employ the upper limit damage predictions of Regulatory Guide 1.99, Revision 1, to establish the changes in RTNDT used in calculating the pressure-temperature operating limits. The operating limits submitted by DPC are calculated for an RTNDT shift of 1650F at the end of the operating period. We calculate by maintaining the RTNDT shift at 1650F, but using the Regulatory Guide to predict radiation damage and assuming an initial RTNDT of 200F, that the resulting fluence will be 1.9 x 1018 n/cm 2.
The reactor vessel wall at 1/4T location is expected to reach this fluence level in 6 EFPY.
We conclude that the proposed pressure-temperature operating limits and chanaes to Technical Specification 3.1.2 are acceptable but only through 6 EFPY instead of 8 EFPY as proposed by DPC. DPC has agreed to this change. For this operating period the proposed pressure-temperature operating limits are in accordance with the fracture toughness re quirements of Appendix G, 10 CFR Part 50.
Compliance with Appendix G in establishing safe operating limitations will ensure adequate safety margins during operation, testing, maintenance and postulated accident conditions and constitute an acceptable basis for satisfying the requirements of NRC General Design Criterion 31, Appendix A, 10 CFR Part 50.
Environmental Consideration We have determined that the amendments do not authorize a change in effluent types or total amounts nor an increase in power level and will not result in any significant environmental impact. Having made this determination, we have further concluded that the amendments involve an action whi-ch is insignificant from the standpoint of environmental impact and, pursuant to 10 CFR §51.5(d)(4), that an environmental impact statement or negative declaration and environmental impact appraisal need not be prepared in connection with the issuance of these amendments.
Conclusion We have concluded, based on the considerations discussed above, that:
(1) because the amendments do not involve a significant increase in the probability or consequences of accidents previously considered and do not involve a significant decrease in a safety margin, the amendments do
-3 not involve a significant hazards consideration, (2) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, and (3) such activities will be conducted in compliance with the Commission's regulations and the issuance of these amendments will not be inimical to the common defense and security or to the health and safety of the public.
Dated: March 19, 1979