E7-24975. Calvert Cliffs Nuclear Power Plant, Inc.; Calvert Cliffs Nuclear Power Plant, Unit No. 1; Exemption

1.0 Background

Calvert Cliffs Nuclear Power Plant, Inc. (the licensee), is the holder of Renewed Facility Operating License Nos. DPR-53 and DPR-69, which authorize operation of the Calvert Cliffs Nuclear Power Plant, Unit Nos. 1 and 2 (Calvert Cliffs 1 and 2), respectively. The license provides, among other things, that the facility is subject to all rules, regulations, and orders of the Nuclear Regulatory Commission (NRC, the Commission) now or hereafter in effect.

The facility consists of two pressurized-water reactors located in Calvert County, Maryland.

2.0 Request/Action

Title 10 of the Code of Federal Regulations (10 CFR), Part 50, Section 50.46, “Acceptance criteria for emergency core cooling systems for light-water nuclear power reactors,” requires, in part, that “Each boiling or pressurized light-water nuclear power reactor fueled with uranium oxide pellets within cylindrical zircaloy or ZIRLO ^TM cladding must be provided with an emergency core cooling system (ECCS) that must be designed so that its calculated cooling performance following postulated loss-of-coolant accidents [LOCAs] conforms to the criteria set forth in paragraph (b) of this section.” Appendix K, “ECCS Evaluation Models,” to 10 CFR Part 50 requires, in part, that the rate of energy release, hydrogen generation, and cladding oxidation from the metal/water reaction shall be calculated using the Baker-Just equation. The Baker-Just equation assumes that the cladding material is composed of either zircaloy or ZIRLO ^TM.

By letter dated February 23, 2007, the licensee requested an exemption from the requirements of 10 CFR 50.46 and Appendix K to 10 CFR Part 50 to allow the use of lead fuel assemblies (LFAs) clad with advanced zirconium-based alloys manufactured by Westinghouse Electric Company and M5 ^TM alloy manufactured by AREVA. The advanced zirconium-based and M5 ^TM alloys are proprietary alloys and are chemically different from either zircaloy or ZIRLO ^TM fuel cladding materials, which are approved for use. Therefore, a plant-specific exemption from these regulations is required to support the use of LFAs that are not manufactured with zircaloy or ZIRLO ^TM.

Previously, by letter dated April 11, 2003, the NRC staff approved the irradiation of 8 LFAs, four Westinghouse LFAs and four AREVA LFAs, for 2 operating cycles in the core of Calvert Cliffs 2. These LFAs were inserted into the Unit 2 core in April of 2003 and remained there during Operating Cycles 15 and 16. Subsequently, by letter dated November 9, 2006, the NRC staff approved the irradiation of 4 LFAs, two Westinghouse LFAs and two AREVA LFAs, for a third operating cycle in either Calvert Cliffs 1 or Calvert Cliffs 2. The licensee subsequently inserted these 4 LFAs into the core of Calvert Cliffs 2 during their spring 2007 refueling outage for operating cycle 17 which is currently ongoing. The remaining 4 LFAs, two Westinghouse LFAs and two AREVA LFAs, were discharged to the spent fuel pool for detailed post-irradiation examinations during the spring 2007 Unit 2 refueling outage.

In the licensee's letter of February 23, 2007, the licensee requested the exemption to support the re-insertion of the remaining 4 LFAs, two Westinghouse LFAs and two AREVA LFAs, for a third operating cycle. These LFAs would be placed in high-duty core locations in Calvert Cliffs 1 for operating cycle 19 in order to gain high burnup experience. The licensee requested to irradiate the LFAs beyond the current burnup limit to a peak rod average of 70,000 MWD/MTU for Calvert Cliffs Unit 1.

3.0 Discussion

Pursuant to 10 CFR 50.12, the Commission may, upon application by any interested person or upon its own initiative, grant exemptions from the requirements of 10 CFR Part 50, when (1) the exemptions are authorized by law, will not present an undue risk to public health or safety, and are consistent with the common defense and security; and (2) when special circumstances are present. Under Section 50.12(a)(2), special circumstances include, among other things, when application of the specific regulation in the particular circumstance would not serve, or is not necessary to achieve, the underlying purpose of the rule.

Authorized by Law

This exemption would allow the licensee to re-insert up to four LFAs, two Westinghouse LFAs and two AREVA LFAs, which contain some fuel rods clad with advanced zirconium-based and M5 ^TM alloys that do not meet the definition of Zircaloy or ZIRLO ^TM as specified by 10 CFR 50.46, into the core of Calvert Cliffs 1. As stated above, 10 CFR 50.12 allows the NRC to grant exemptions from the requirements of 10 CFR Part 50. The NRC staff has determined that granting of the licensee's proposed exemption will not result in a violation of the Atomic Energy Act of 1954, as amended, or the Commission's regulations. Therefore, the exemption is authorized by law.

No Undue Risk to Public Health and Safety

The underlying purposes of 10 CFR 50.46 is to establish acceptance criteria for ECCS performance. Previously, the Westinghouse safety evaluation (WCAP-15874-NP, Revision 0, “Safety Analysis Report for Use of Improved Zirconium-based Cladding Materials in Calvert Cliffs Unit 2 Batch T Lead Fuel Assemblies,” dated April 2002) and approved Framatome ANP Topical Report (BAW-10227P-A, “Evaluation of Advanced Cladding and Structural Material (M5) in PWR Reactor Fuel,” Framatome Cogema Fuels, February 2000) demonstrated the acceptability of the advanced zirconium-based and M5 ^TM cladding under LOCA conditions. The unique features of the LFAs were evaluated for effects on the LOCA analysis. The results showed that the LFAs would not adversely affect the ECCS performance. Since the four LFAs will be located at high-duty other than LOCA-limiting core locations, the licensee concludes that the LOCA safety analyses will remain bounding for these LFAs for Calvert Cliffs 1.

Paragraph I.A.5 of Appendix K to 10 CFR Part 50 states that the rates of energy, hydrogen concentration, and cladding oxidation from the metal-water reaction shall be calculated using the Baker-Just equation. Since the Baker-Just equation presumes the use of zircaloy clad fuel, strict application of the rule would not permit use of the equation for the advanced zirconium-based and M5 ^TM alloys for determining acceptable fuel performance. The underlying intent of this portion of the Appendix is to ensure that analysis of fuel response to LOCAs is conservatively calculated. The Westinghouse safety evaluation and approved AREVA topical report show that, due to the similarities in the chemical composition of the advanced zirconium-based and M5 ^TM alloys and zircaloy, the application of the Baker-Just equation in the analysis of the advanced zirconium-based and M5 ^TM clad fuel rods will continue to conservatively bound all post-LOCA scenarios. Thus, the application of Appendix K, Paragraph I.A.5 is not necessary to achieve its underlying purpose in these circumstances.

Based on the acceptable performance of 8 LFAs in the Calvert Cliffs 2 reactor core during operating cycles 15 and 16, the staff concludes that the licensee has demonstrated that the four LFAs will perform adequately under LOCA conditions, and thus the LFAs are acceptable for operation for Calvert Cliffs 1 operating cycle 19. Based on the above, the staff concludes that it is acceptable to grant an exemption from the requirements of 10 CFR 50.46, and Appendix K to 10 CFR Part 50 for Calvert Cliffs 1.

Based on the above, no new accident precursors are created by the exemption to allow use of advanced zirconium-based and M5 ^TM alloy clad fuel, thus, the probability of postulated accidents is not increased. Also, based on the above, the consequences of postulated accidents are not increased. Therefore, there is no undue risk [since risk is probability × consequences] to public health and safety.

Consistent With Common Defense and Security

The proposed exemption would allow the use of LFAs with advanced cladding materials. This change to the plant core configuration has no relation to security issues. Therefore, the common defense and security is not impacted by this exemption.

Special Circumstances

Special circumstances, in accordance with 10 CFR 50.12(a)(2)(ii), are present whenever application of the regulation in the particular circumstances is not necessary to achieve the underlying purpose of the rule. The underlying purpose of 10 CFR 50.46 and Appendix K to 10 CFR Part 50 is to establish acceptance criteria for ECCS performance. The licensee stated that the wording of the regulations renders the criteria of 10 CFR 50.46 and Appendix K inapplicable to the advanced zirconium-based and M5 ^TM alloy clad fuel, even though the approved Westinghouse safety evaluation and AREVA topical report shows that the intent of the regulations are met. Therefore, since the underlying purpose of 10 CFR 50.46 and Appendix K to 10 CFR Part 50 is achieved with the use of the advanced zirconium-based and M5 ^TM alloy clad fuel, the special circumstances required by 10 CFR 50.12(a)(2)(ii) for granting of an exemption from 10 CFR 50.46 and Appendix K exist.

4.0 Conclusion

Accordingly, the Commission has determined that, pursuant to 10 CFR 50.12(a), the exemption is authorized by law, will not present an undue risk to the public health and safety, and is consistent with the common defense and security. Also, special circumstances are present. Therefore, the Commission hereby grants the licensee an exemption from the requirements of 10 CFR 50.46 and 10 CFR Part 50, Appendix K with respect to the use of LFAs with advanced zirconium-based and M5 ^TM alloy clad fuel.

Pursuant to 10 CFR 51.32, the Commission has determined that the granting of this exemption will not have a significant effect on the quality of the human environment (72 FR 71449).

This exemption is effective upon issuance.

Dated at Rockville, Maryland, this 17th day of December 2007.

For the Nuclear Regulatory Commission.

Catherine Haney,

Director, Division of Operating Reactor Licensing, Office of Nuclear Reactor Regulation.