ML16138A690
| ML16138A690 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 12/15/1989 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML16138A689 | List: |
| References | |
| NUDOCS 9001020019 | |
| Download: ML16138A690 (4) | |
Text
S pB REG&
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, 0. C. 20555 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO.180 TO FACILITY CPERATING LICENSE DPR-38 AV!ENDMENT KO.180 TO FACILITY OPERATING LICENSE DPR-47 AMENDMENT NO.177 TO FACILITY OPERATING TICENSE DPR-55 DUKE POWER COMPANY OCONEE NUCLEAR STATION, UNITS 1,2 AND 3 COCKETS NO5.
50-269, 50-270 AND 50-287
1.0 INTRODUCTION
Ry letter dated September 25, 1989, Duke Power Company, the licensee for operation of Oconee Nuclear Station (ONS),
Units 1, 2 and 3, requested an amendment to the ONS Units 1, 2 and 3 Technical Specifications (TSs) to support operation of Unit 3 at full rated power during Cycle 12.
Specifically, the TS change request is to (1) revise the flux/flow/imbalance safety limits in Figure L.1-2 by reaucing the allowable thermal power level and imbalance for the three-and four-reactor coolant pump operations, (2) remove specifications associated with two-pump operation from the TSs including Figures 2.1-2 and 2.3-2, and Table 2.3-1, and (3) minor editorial changes to reflect the use of the VIPRE code for the core thermal hydraulic aralysis ano revise the radial peaking factor from 1.71 to 1.714.
2.0 EVALUATION In support of the Unit 3, Cycle 12 operation, the licensee, in Attachment 3 of the September 25, 1989 letter, provided the Oconee Unit 3, Cycle 12 Reload Report, DPC-RD-2C14. The Cycle 12 core will use 52 fresh Batch 14 Mark-B8 fuel assemblies, and 125 fuel assemblies from the previous cycles with the majority being Batches 12B and 13 fuel assemblies, i.e., Mark-85Z and Mark-B7 assenblies. Forty-four of the 52 Batch 14 assemblies have burnable poison rod assemblies (BPRAs) inserted. Thirty-six (36) of the EPRAs are new, and the remaining 8 are once burned.
The Batch 14 Vark-B8 assemblies are similar to the Mark-B7 fuel previcusly reloaded into Cycle 11.
Both fuel designs have intermediate zircaloy spacer grids. New features for Mark-88 include a debris fretting resistant fuel rod design, which utilizes a lengthened solid lower end plug extendina below the bottom end grid, and a slightly reduced fuel rod prepressurization level to compensate for the reduction in plenum volume. The Mark-B8 fuel also has higher initial enrichment than that loaded in the previous cycles. Because of variation in the shuffle pdttern and changes in the radial flux and burnup 9000102001 9 8 9 12 1 5 PDR ADOCK 05000269 PNU
-2 distributions, the physics parameters and the ejected and stuck rod worths are different between Cycles 11 and 12.
These physics characteristics were calculated with the approved CASMO-2 based reload design methods. The resulting rod worth and shutdown margin are shown in Tables 5-1 and 5-2 of the Reload Report.
With the recent approval of Topical Report DPC-NE-2003A, "Oconee Nuclear Station Core Thermal Hydraulic Methodology Using VIPRE-01," the Cycle 12 thermal hydraulic analysis was done with the VIPRE-01 code.
Of the 177 fuel assemblies in the core, only 4 assemblies have Inconel spacer grids and the remainder (Mark-8Z design) have zircaloy spacer grids. The Mark-BZ fuel assemblies have a slightly higher pressure drop than the other assemblies as a result of the increased flow resistance of the zircaloy spacer grids. The Cycle 12 transition ccre was conservatively analyzed at the limiting thermal design conditions for the limiting two-pump coastdown transient and a flux to flow trip setpoint of 1.07.
The resulting minimum departure from nucleate boiling ratio (DNBR) is greater than the BWC critical heat flux correlation limit of 1.18.
The licensee performed the reload analysis using the approved reload design methodology described in DPC-NE-1002A, "Oconee Nuclear Station Reload Design Methodology II."
The flux/flow/imbalance safety limit change is necessary because of the minor changes in the power peaking and control rod worth. The changes in safety limits also affect the limiting safety system settings.
The flux/flow/imbalance safety limit change is a result of maneuvering analysis on fuel depletion, integral rod worth, and power maneuver. For the four-pump operation, the maximum power imbalance is reduced from the current value of 49.5 percent to 48 percent. For three-pump operation, the maximum allowable power level is reduced from 88.07 percent to 84.9 percent. The calculation of the allowable power level for the three-pump operation is based on an assumed reactor coolant system flow rate of 74.7 percent of the rated flow, a flux/flow trip setpoint of 1.07, and a power measurement uncertainty of 5 percent. This method is the same as that for the previous cycles except that the power uncertainty of 5 percent is obtained using the square root of sum of the squares method to account for the uncertainties associated with heat balance error, TS allowance for calibration of the excore detectors to the heat balance, transient nuclear instrument error, and an allowance for the uncertainty of the flux/flow imbalance trip function hardware. Since the error adjustment of the flux/flow/imbalance safety limits would result in a setpoint of 79.9 percent, the same as the current Reactor Protection System (RPS) maximum allowable setpoint, the RPS allowable setpoint inFigure 2.3-2 was unchanged.
The analysis employs analytical techniques and design bases established in reports that were previously accepted by NRC. All of the accidents analyzed in the Final Safety Analysis Report (FSAR) have been reviewed for Cycle 12 operation. A comparison of the key parameters for accident analysis, such as Doppler and moderator coefficients, rod worth and boron reactivity worth, is provided in Table 7.1 of the reload report. A review of these key parameters by the licensee has determined that the Cycle 12 characteristics were conservative compared to those analyzed for previous cycles. Therefore, no new accident analyses were performed. The TS modifications required for Cycle 12 operation are justified.
-3 Other TS changes are essentially editorial changes. The change of the enthalpy rise factor from 1.71 to 1.714 is to be consistent with the actual value used in the analysis. Because the licensee's proposal does not include two-pump operation, TS items associated with two-pump operations are to be deleted. The Cycle 12 reload report also indicated that the figures for operating limits on rod index and axial power imbalance have been removed from the TSs and included in the cycle-specific Core Operating Limits Report (COLR).
This removal was approved by NRC in Amendments Nos. 172, 172, and 169 to the operating licenses for ONS, Units 1, 2 and 3, issued January 26, 1989.
Since Oconee Units 1, 2 and 3 have common TSs, the changes on Unit 3 also affect Units 1 and 2. The September 25, 1989, letter indicated that changes which affect Units 1 and 2 will be implemented upon Unit 3 Cycle 12 startup.
Even though there is no supporting analysis to justify the TS changes for Units 1 and 2, we find that they are acceptable because (1) the flux/flow/imbalance safety limit change is in a more restrictive, conservative direction, and (2) other changes are only editorial changes.
The NRC staff has reviewed the licensee's request for TS changes to support the Unit 3, Cycle 12 operation. We have found that the TS changes are either editorial or supported by the reload safety analysis performed with approved methods, and therefore are acceptable. The TS changes are also acceptable for Units 1 and 2.
3.0 ENVIRONMENTAL CONSIDERATION
These amendments involve changes in requirements with respect to the installation or use of facility components located within the restricted area as defined in 10 CFR Part 20. We have 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 these amendments involve no significant hazards consideration, and there has been no public comment on such finding.
Accordingly, the amendments meet the eli ibility 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 these amendments.
4.0 CONCLUSION
The Commission made a proposed determination that the amendments involve no significant hazards consideration which was published in the Federal Register (54 FR 46146) on November 1, 1989, and consulted with the State of South Carolina. No public comments were received, and the State of South Carolina did not have any comments.
We have 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, and (2) such activities
-4 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.
Principal Contributor:
Y. Hsii, SRXB/DST Dated: December 15, 1989