ML14183A373
| ML14183A373 | |
| Person / Time | |
|---|---|
| Site: | Robinson  |
| Issue date: | 03/16/1998 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML14183A372 | List: |
| References | |
| NUDOCS 9803190408 | |
| Download: ML14183A373 (4) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 205-001
.SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 178 TO FACILITY OPERATING LICENSE NO. DPR-23 CAROLINA POWER & LIGHT COMPANY H. B. ROBINSON STEAM ELECTRIC PLANT. UNIT NO. 2 DOCKET NO. 50-261 1.0 INTROD2UCTION By letter dated December 17, 1997, as supplemented by letters dated February 6, 1998 and March 12, 1998, the Carolina Power & Light Company (the licensee) submitted a request for changes to the H. B. Robinson Steam Electric Plant, Unit No. 2 (HBR), Technical Specifications (TS). The requested changes revise TS Section 5.6.5, *Core Operating Limits Report,' and associated TS bases, to reflect approval of a new method for correlation of departure from nucleate boiling (DNB) parameters based upon DNB test data for high thermal performance (HTP) fuels. The approved method is contained in Siemens Power Corporation Topical Report, EMF-92-153(P)(A), "HTP: Departure from Nucleate Boiling Correlation for High Thermal Performance Fuel.' The February 6 and March 12, 1998 submittals contained clarifying information and did not alter the initial no significant hazards consideration determination published in the Federal Register on January 28, 1998.
2.0 EVALUATION In order to ensure that integrity of the fuel cladding is maintained, overheating of the fuel clad must be prevented under all operating conditions. It is known that by ensuring that regions of the core remain below the upper limit of the nucleate boiling heat transfer regime, fuel clad temperatures can be maintained at acceptable values. Operation beyond the upper limit of the nucleate boiling regime is termed departure from nucleate boiling. For pressurized water reactors, such as HBR, operational limits are developed to ensure that regions of the core do not achieve or proceed beyond DNB for all normal operations and expected transients. These safety limits are expressed in terms of a ratio of power needed to achieve DNB to actual core power. This ratio is known as the Departure from Nucleate Boiling Ratio (DNBR). Plant safety limits are expressed in term of the DNBR.
Appropriate safety limit (SL) DNBR values are calculated using analytical methods capable of predicting core conditions under various operating conditions. The approved analytical methods are listed in Section 5.6.5, 'Core Operating Limits Report,' in the HBR Technical Specifications. The licensee has proposed to change the analytical methods used to calculate the SL DNBR for one type of fuel currently in use and to revise Section 5.6.5 of the TS accordingly.
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Specifically, the licensee currently references ANF-1224(P), 'Departure from Nucleate Boiling Correlation for High Thermal Performance Fuel" (ANFP) as the approved.methodology for the correlation used to evaluate the DNBR safety limit for HTP fuel. For HTP fuel, the ANFP correlation gives a DNBR safety limit of 1.154. ANF-1224(P) is currently listed in TS 5.6.5 as an approved methodology for use in developing the periodic Core Operating Limits Report.
The licensee has proposed to use a new NRC-approved correlation described in EMF-92 153(P), "HTP: Departure From Nucleate Boiling Correlation for High Thermal Performance Fuel..This correlation was submitted to the NRC by the Siemens Power Corporation in September 1992. Use of the new correlation results in a SL DNBR for HTP PWR fuels of 1.141.
As documented in its safety evaluation (SE) dated December 23, 1993, the NRC staff reviewed the topical report and approved it for use in license applications. The staff conditioned use of the correlation on the successful satisfaction of several conditions. Those conditions are that:
(1) the HTP critical heat flux correlation is applicable to fuels whose design characteristics fall within the values for certain parameters specified in Table 2 of the December 1993 SE.
(2) the application of the HTP correlation for DNB analysis is restricted to the operating conditions specified in Table 1 of the December 1993 SE.
In the amendment application, the licensee stated that both of these conditions are satisfied by application of the HTP correlation to the HTP fuel at HBR. In a supplemental submittal dated February 6, 1998, the licensee specified expected HBR values for each of the parameters listed in Table 1 and Table 2 of the December 1993 SE. The staff reviewed the values specified by the licensee and confirmed they fell within the allowable ranges specified in the December 1993 SE.
Although the EMF-92-153(P) correlation determined a new DNBR safety limit for HTP fuel, the safety limit curves in Figure 2.1.1-1 of the TS are unchanged. The curves In Figure 2.1.10-1 represent the loci of points of thermal power, reactor coolant system pressure and reactor vessel inlet temperature for which the minimum DNBR is not less than the safety limit as determined by an appropriate correlation. For HBR, the TS bases and Updated Final Safety Analysis Report present DNBR safety limits for HTP fuel assemblies and standard mixing vane fuel assemblies, both of which are used at HBR. The DNBR safety limit for standard mixing vane fuel is determined by a separate, approved, correlation and has a current value of 1.17.
This value is more restrictive than either the existing or proposed safety limit for HTP fuel assemblies. As a result, the safety limit curves in Figure 2.1.1-1, which ensure that the most restrictive DNBR safety limit (in this case the standard mixing vane fuel safety limit) is not violated, remain unchanged.
Subsequent to the staffs December 1993 SE on EMF-92-153(P), the vendor issued EMF-92 153(P)(A) Revision 0 and Supplement I in March 1994 which reflected the approved version of
the methodology and incorporated the staffs SE. The licensee proposed to revise TS Section 5.6.5 and Bases Sections 2.1.1, 3.2.2 and 3.4.1 to reference the topical report EMF-92 153(P)(A) Revision 0 and Supplement I and the new HTP DNBR safety limit value of 1.141.
Use of NRC-approved methodology will ensure that values for cycle specific parameters are determined such that all applicable limits (e.g., nuclear limits, fuel thermal and mechanical limits, and transient analysis limits) of the safety analysis are met. The staff has determined that this topical report is appropriate for use at HBR. Therefore, the TS change is acceptable The licensee also revised the Bases Section 2.1.1 to reflect reference to the correct methodology by which the DNBR limit for the standard mixing vane fuel is determined. This methodology, XN-NF-621 (P)(A) Revision 1, *Exxon Nuclear DNB Correlation for PWR Fuel Designs,* Exxon Nuclear Company, September 1983, was included in the TS by amendment 141 which implemented the COLR on July 15, 1992. However, the reference to XN-NF-621 was inadvertently omitted from the Bases at that time. Thus, the licensee is now revising the Bases to delete reference to a previous methodology (XN-NF-71 1) and insert reference to XN NF-621, which as described above, is already included in the TS. The staff finds this administrative correction acceptable.
Based on the licensee's demonstration that it met the conditions in the December 1993 SE for use of Topical Report EMF-92-153 in licensing applications, thus demonstrating an acceptable basis for plant safety limits, the staff concluded the licensee's proposed changes are acceptable.
3.0 STATE CONSULTATION
In accordance with the Commission's regulations, the State of South Carolina official was notified of the proposed issuance of the amendment. The State official had no comments.
4.0 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 amendment also changes record keeping and reporting requirements. 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 (63 FR 4309).
Accordingly, the amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9) and (c)(1 0). 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.
-4 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 Contributors: JShea LKopp Date: March 16, 1998