ML16138A656
| ML16138A656 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 01/26/1989 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML16138A655 | List: |
| References | |
| NUDOCS 8902020321 | |
| Download: ML16138A656 (9) | |
Text
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0 UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO.172 TO FACILITY OPERATING LICENSE DPR-38 AMENDMENT NO. 172TO FACILITY OPERATING LICENSE DPR-47 AMENDMENT NO. 169TO FACILITY OPERATING LICENSE DPR-55 DUKE POWER COMPANY OCONEE NUCLEAR STATION, UNITS 1, 2 AND 3 DOCKET NOS. 50-269, 50-270 AND 50-287
1.0 INTRODUCTION
By letter dated September 3, 1987 (Ref. 1), as supplemented on February 27 (Ref. 5), September 9 (Ref. 6), and September 20, 1988 (Ref. 8), Duke Power Company (DPC or the licensee) proposed revisions to the Technical Specifications (TS) for Oconee Nuclear Station, Units 1, 2, and 3. The revisions to the TS would provide an alternative method for specifying the values of cycle-specific control rod position limit curves and axial imbalance (with imbalance being related to the axial flux difference between the top and bottom of the core) limit curves for affected TS. The purpose of the submittal was to obtain approval of the concept and the wording of affected TS, not to obtain approval of specific limiting curves for any Oconee Station current or future reload fuel cycle. The Oconee units are being used as the lead-plants to develop an acceptable alternative to specifying the values of cycle-specific parameters limits in the TS.
The elements of the DPC concept consist of three separate actions to revise the station's TS: (1) the addition of the definition of a named formal report called the Core Operating Limits Report (COLR) that includes the values of cycle-specific parameter limits that have been established using an NRC-approved methodology and consistent with all applicable limits of the safety analysis; (2) the addition of an administrative reporting requirement to submit the formal report on cycle-specific parameter limits to the Commission for information; and (3) the modification of individual TS to note that cycle-specific parameters shall be maintained within the limits provided in the defined formal report. There would be no prior staff review of the COLR. Thus, no staff amendment to the station's TS would be required for future reloads which alter these parameters. The COLR would be submitted to the NRC, the Regional Administrator, and the Resident Inspector upon issuance for each reload cycle.
This concept and procedure would only apply to those TS specified by TS 6.9, which are included in the COLR, and whose limit values and limit curves exhibit only nominal cycle-to-cycle variations. These limit values and limit curves may be generated, prior to implementation, as a function of cycle burnup or generated, after cycle operation begins, for implementation during a particular portion of the cycle. Revisions to TS that are not included in this
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-2 concept, but which would be required by a core reload or other considerations, would be processed in accordance with the current license amendment procedures.
The analytical methods and procedures, which will be used by DPC, have been documented in topical reports (Refs. 2 and 3).
These topical reports have been reviewed and approved by the NRC. DPC currently uses these analytical methods and procedures to calculate cycle-specific control rod position limit curves and axial imbalance limit curves for the Oconee Units' TS. The staff review of these cycle specific limit curves consists of confirmation that the new limits have been calculated using approved methods. The new limits are reviewed by the staff by also noting the trends from previous cycles and staff experience with other reloads. The proposed revisions to the form of the TS and associated COLR permit the staff to continue to trend cycle-specific limit values. It should be noted that, in some cases, audit calculations are performed for the staff by consultants to independently verify a vendor's or licensee's determination of TS limit values or curves (see Reference 4 for an example).
The staff evaluation of this DPC proposal regarding certain cycle-specific TS and the COLR follows.
2.0 EVALUATION There are two regulations which must be considered in the staff's evaluation of the DPC proposal. These are 10 CFR 50.36 and 10 CFR 50.59. The first of these, 10 CFR 50.36, is directly concerned with TS. This regulation specifies that an applicant must submit proposed TS with an application for a license authorizing operation of a production or utilization facility. The licensee.
application must meet the guidance of this regulation. The second regulation, 10 CFR 50.59, provides guidance on making changes, performing tests, and performing experiments by the holder of a license authorizing operation of a production or utilization facility.
The pertinent sections of 10 CFR 50.36 for this evaluation are:
"... the technical specifications will be derived from the analyses and evaluation included in the safety analysis report, and amendments thereto, submitted pursuant to Section 50.34....
"Limiting conditions for operation are the lowest functional capability or performance levels of equipment required for safe operation of the facility....
-3 10 CFR 50.36.(c)(3)
"Surveillance requirements are requirements relating to test, calibration or inspection to assure that the necessary quality of systems and components is maintained, that facility operation will be within the safety limits, and that the limiting conditions of operation will be met."
"Administrative controls are provisions relating to...
and reporting necessary to assure operation of the facility in a safe manner..
The current method of controlling reactor physics parameters to assure conformance to 10 CFR 50.36 is to specify the specific value(s) determined to be-within specified acceptance criteria (usually the limits of the safety analyses) using an approved calculation methodology. The alternative contained in this DPC concept controls the values of cycle-specific parameters and assures conformance to 10 CFR 50.36, which calls for specifying the lowest functional performance levels acceptable for continued safe operation, by specifying the calculation methodology and acceptance criteria. This permits operation at any specific value determined by the licensee, using the specified methodology, to be within the acceptance criteria. The COLR will document the specific values of parameter limits resulting from DPC's calculations including any mid-cycle revisions to such parameter values.
The staff concludes that the DPC concept meets the intent of this regulation because 10 CFR 50.36 (1) does not specify that numerical values are required to be used for Limiting Conditions for Operation (LCO), (2) does not prohibit the specification of an LCO limit by referencing another document, and (3) does allow for the submittal of reports to assure the safe operation of the facility.
The regulation embodied in 10 CFR 50.59 allows the holder of a license authorizing operation of a production or utilization facility to do the following:
(i) make changes in the facility as described in the safety analysis report, (ii) make changes in the procedures as described in the safety analysis report, and (iii) conduct tests or experiments not described in the safety analysis report, without prior Commission approval, unless the proposed change-, test or experiment involves a change in the technical specifications incorporated in the license or an unreviewed safety question."
-. 4 The DPC proposal does not involve an unreviewed safety question because all limit curves in COLR will be generated by using analytical methods and procedures that are specified in the TS and have been reviewed and approved by the staff. The proposal does not involve a TS revision because the TS need not be revised when cycle-specific limit curves are changed.
Only the COLR will be revised so that the appropriate COLR for the cycle in question will be applicable in accordance with the definition of the COLR which would be provided in the TS Definition Section. No prior approval of COLR would be required when cycle-specific revisions are necessary. Therefore, the staff concludes that the DPC concept, concerning the use and revisions to COLR, does not constitute a TS revision and is fully in conformance with the provisions of 10 CFR 50.59 and does not require the staff to issue a future license amendment.
In addition to meeting the requirements of the regulations specified in 10 CFR 50.36 and 10 CFR 50.59, the DPC concept on an alternative formulation of TS meets the characteristics listed below:
(1) The TS provide a limit value or curve which has been assumed to be an initial condition of, or is the result of, the plant safety analysis.
Plant operation beyond the TS limit would place the plant in an unanalyzed state and thus result in an unreviewed safety question. Thus there is a need for the limit value or limit curves to appear in the TS.
(2) The limit values or limit curves are cycle-specific and are usually changed each cycle.
(3) The limit values or limit curves are calculated by methods and procedures that have been reviewed arid approved by the NRC for use at the plant.
(4) The limit values or curves are the result of usually complex calculations.
The NRC review of such limit values or curves consists of comparison with previous values and observing trends from cycle-to-cycle and plant-to-plant.
In some instances, the staff performs audit calculations to independently confirm the accuracy of calculation of a particular parameter by a licensee or vendor.
These characteristics recognize that (1) there is a need to provide the limit value or curves in the TS, (2) the staff performs only a limited review of the limit values or curves, (3) the limit values or curves may change each cycle, and (4) approved methods and procedures are used to calculate the limit values or curves. Thus the staff concludes that these characteristics provide an acceptable basis for-determining which TS should be treated by DPC's alternate formulation of TS.
-5 In sum, the staff finds the DPC approach acceptable as follows:
(1) The limit values or limit curve remain quantitatively identified in TS as limits on plant operation.
(2) A TS revision is not required each cycle. This assumes that there are no other TS revision for the cycle or unreviewed safety questions. The implication of this is that a significant savings in resources can be made by the NRC in not having to review and issue a license amendment for a reload in which only minor changes to cycle-specific parameters are needed. There is also a significant resource.savings to the licensee in not having to support a reload licensing effort.
(3) The report containing the cycle specific parameters will still be available to the staff, after its implementation at a plant, for use in trending parameters.
(4) Licensees no longer need to operate their plants with restrictive bounding limit values or curves. Use of the Duke concept will allow more flexible and optimum cycle design and operation.
(5) Licensees will perform a safety analysis for each cycle.regardless of whether or not the alternative TS formulation is used.
(6) The new alternative forms of the TS are considered to be improvements to the TS and thus in line with the Commission's stated policy for improving TS (see 52FR3788 of February 6, 1987).
(7) The DPC concept recognizes the limited nature of the NRC's review of some of the more complex cycle dependent TS and the trivial changes encountered, in most cases, in some TS limit values.
3.0 TECHNICAL SPECIFICATIONS The acceptable wording for the revisions to the affected TS for the Oconee station are as follows:
(1) Definition 1.9 CORE OPERATING LIMITS REPORT The CORE OPERATING LIMITS REPORT is the unit-specific document that provides core operating limits for the current reload cycle. These cycle-specific core operating limits shall be determined for each reload cycle in accordance with Specification 6.9.
Plant operation within these core operating limits is addressed in individual specifications.
-6 (2) Technical Specification 3.1.3.5 and Bases 3.1.3.5 Except for physics tests...
during the approach to criticality. The regulating rods shall then be positioned within the acceptable operating limits for regulating rod position provided in the CORE OPERATING LIMITS REPORT.
Bases (The Duke Power Company's submittal of September 3, 1987 is acceptable with regard to the wording of the last sentence of the last paragraph on Technical Specification Page 3.1-9.)
(3) Technical Specification 3.1.11 Bases (The Duke Power Company's submittal of September 3, 1987 is acceptable with regard to the wording of the second paragraph of the Bases on Technical Specification Page 3.1-23.)
(4) Technical Specification 3.5.2.2.d.2.c 3.5.2.2.d.2.c Position the remaining rods...
limits of Specification 3.5.2.2.a and within the acceptable operating rod position withdrawal/insertion limits for regulating rod position provided in the CORE OPERATING LIMITS REPORT.
(5) Technical Specification 3.5.2.3 3.5.2.3 The worths of single inserted control rods during criticality are limited by the restrictions of Specification 3.1.3.5 and the control rod position limits provided in the CORE OPERATING LIMITS REPORT.
(6) Technical Specification 3.5.2.5.c 3.5.2.5.c Position limits are specified for regulating and axial power shaping control rods. Except for physics tests or exercising control rods, the regulating control rod insertion/withdrawal limits shall be maintained within the acceptable operating limits for regulating rod position provided in the CORE OPERATING LIMITS REPORT for the particular number of operating reactor coolant pumps (4, 3, 2).
10
-7 (7) Technical Specification 3.5.2.6 3.5.2.6 Reactor power imbalance shall be monitored on a frequency not to exceed two hours during power operation above 40 percent rated power. Except for physics tests, imbalance shall be maintained within the acceptable operating limits for reactor power imbalance provided in the CORE OPERATING LIMITS REPORT.
(8) Technical Specification 3.5.2.6 Bases (The Duke Power Company's submittal of September 3, 1987 is acceptable with regard to the wording of the first sentence of the second paragraph of Technical Specification Page 3.5-11.)
(9) Technical Specification 3.5.2 Bases (The Duke Power Company's submittal of September 3, 1.987 is acceptable with regard to the wording of (1) the first sentence of the first paragraph and (2) the last paragraph of Technical Specification Page 3.5-12.)
(10) Technical Specification 6.9 6.9 CORE OPERATING LIMITS REPORT Specifi cati on 6.9.1 Core operating limits shall be established prior to each reload cycle, or prior to any remaining part of a reload cycle, for the following:
(1) Power Dependent Rod Insertion Limits for Specifications 3.1.3.5, 3.5.2.2.d.2.c, 3.5.2.3, and 3.5.2.5.c.
(2)
Power Imbalance Limits for Specification 3.5.2.6.
and shall be documented in the CORE OPERATING LIMITS REPORT.
6.9.2 The analytical methods used to determine the core operating limits shall be those previously reviewed and approved by the NRC, specifically:
(1) DPC-NE-1002A, Reload Design Methodology II, October 1985.
(2) NFS-1001A, Reload Design Methodology, April 1984.
-8 6.9.3 The core operating limits shall be determined such that all applicable limits (e.g., fuel thermal-mechanical limits, core thermal-hydraulic limits, ECCS limits nuclear limits such as shutdown margin, and transient and accident analysis limits) of the safety analysis are met.
6.9.4 The CORE OPERATING LIMITS REPORT, including any mid-cycle revisions or supplements shall be provided, upon issuance for each reload cycle, to the NRC Document Control Desk with copies to the Regional Administrator and Resident Inspector.
The staff has reviewed the DPC's alternative method for specifying the values of cycle-specific control rod position limit curves and axial imbalance limit curves for affected TS. Affected TS (control rod position limit curves and axial imbalance limit curves) would no longer contain the numerical values for these limits but would reference the values in a COLR. The COLR will be a defined term, and its requirements will be specified by Specification 6.9.
Based on the evaluation discussed above, the staff concludes that DPC's alternative method for formulating cycle-specific TS is acceptable providing that the formulation and wording of Section 3 for the definition of the COLR, affected Specifications, and Specification 6.9 are followed.
4.0 ENVIRONMENTAL CONSIDERATION
These amendments involve a change in the installation or use of facility com ponents located within the restricted area as defined in 10 CFR Part 20. The 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 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.
5.0 CONCLUSION
The Commission made a proposed determination that the amendments involve no significant hazards consideration which was published in the Federal Register (53 FR 50325) on December 14, 1988, and consulted with the state of South Carolina.
No public comments were received, and the state of South Carolina did not have any comments.
99 The staff 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, and (2) 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.
6.0 REFERENCES
- 2. "Reload Design Methodology II," DPC-NE-1002A, Duke Power.Company, October 1985.
- 3. "Reload Design Methodology," NFS-1001A, Duke Power Company, April 1984.
- 4. "Implementation of LOCA Linear Heat Generation Limits by Restricting Control Rod Operation," BNL Memorandum from P. Neogy to J. F. Carew, dated March 26, 1986.
- 7. Letter from D. B. Matthews (NRC) to H. B. Tucker (DPC), dated August 23, 1988.
- 8.
Letter from Hal B. Tucker (DPC) to USNRC, dated September 20, 1988.
Principal Contributors:
Helen N. Pastis, PD#II-3/DRP-I/II Daniel B. Fieno, SRXB/NRR Dated: January 26, 1989