[Federal Register Volume 71, Number 165 (Friday, August 25, 2006)]
[Notices]
[Pages 50475-50477]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E6-14106]


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NUCLEAR REGULATORY COMMISSION

[Docket No. 50-285]


Omaha Public Power District, Fort Calhoun Station, Unit 1; 
Exemption

1.0 Background

    The Omaha Public Power District (OPPD, licensee) is the holder of 
Facility Operating License No. DPR-40 which authorizes operation of the 
Fort Calhoun Station, Unit 1 (FCS). The license provides, among other 
things, that the facility is subject to all rules, regulations, and 
orders of the Nuclear Regulatory Commission (NRC, Commission) now or 
hereafter in effect.
    The facility consists of a pressurized-water reactor located in 
Washington County, Nebraska.

2.0 Request/Action

    Title 10 of the Code of Federal Regulations (10 CFR) 50.46, 
``Acceptance criteria for emergency core cooling systems for light-
water nuclear power reactors,'' requires, among other items, that 
``[e]ach boiling or pressurized light-water nuclear power reactor 
fueled with uranium oxide pellets within cylindrical zircaloy or ZIRLO 
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 
to 10 CFR Part 50, ``ECCS Evaluation Models,'' requires, among other 
items, 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 regulations of 10 CFR 50.46 and 10 
CFR Part 50, Appendix K, make no provisions for use of fuel rods clad 
in a material other than zircaloy or ZIRLO. Since the chemical 
composition of the M5 alloy differs from the specifications for 
zircaloy or ZIRLO, a plant-specific exemption is required to allow the 
use of the M5 alloy as a cladding material or in other assembly 
structural components at FCS.

[[Page 50476]]

Therefore, by letter dated August 11, 2005, as revised by letter dated 
November 8, 2005, and as supplemented on April 12, 2006, the licensee 
requested the use of the M5 advanced alloy for fuel rod cladding and 
other assembly structural components at FCS.

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.

Authorized by Law

    This exemption results in changes to the operation of the plant by 
allowing the use of the M5 alloy as fuel cladding material or for other 
assembly structural components in lieu of zircaloy or ZIRLO. 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 and 10 CFR Part 50, 
Appendix K, are to ensure that facilities have adequate acceptance 
criteria for the ECCS, and to ensure that cladding oxidation and 
hydrogen generation are appropriately limited during a LOCA and 
conservatively accounted for in the ECCS evaluation model, 
respectively. Topical Report (TR) BAW-10227P, ``Evaluation of Advanced 
Cladding and Structural Material (M5) in PWR [pressurized-water 
reactor] Reactor Fuel,'' which was approved by the NRC on February 4, 
2000, demonstrated that the effectiveness of the ECCS will not be 
affected by a change from zircaloy to M5. In addition, TR BAW-10227P 
demonstrated that the Baker-Just equation (used in the ECCS evaluation 
model to determine the rate of energy release, cladding oxidation, and 
hydrogen generation) is conservative in all post-LOCA scenarios with 
respect to the use of M5 advanced alloy as a fuel rod cladding material 
or in other assembly structural components. Based on the above, no new 
accident precursors are created by using M5 advanced alloy, thus, the 
probability of postulated accidents is not increased. Also, based on 
the above, the consequences of postulated accidents are not increased. 
In addition, the licensee will use NRC-approved methods for the reload 
design process for FCS reloads with M5. Therefore, there is no undue 
risk to public health and safety due to using M5.

Consistent With Common Defense and Security

    The proposed exemption requested results in changes to the 
operation of the plant by allowing the use of the M5 alloy as fuel 
cladding material or in other assembly structural components in lieu of 
zircaloy or ZIRLO. This change to the fuel material used in the plant 
has no relation to security issues. Therefore, the common defense and 
security are not impacted by this exemption request.

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 would not serve the underlying purpose of the rule or is 
not necessary to achieve the underlying purpose of the rule. In this 
circumstance neither 10 CFR 50.46 nor 10 CFR Part 50, Appendix K, 
explicitly allows the use of M5 as a fuel rod cladding material or in 
use of other assembly structural components.
    The underlying purpose of 10 CFR 50.46 is to ensure that facilities 
have adequate acceptance criteria for the ECCS. On February 4, 2000, 
the NRC staff approved TR BAW-10227P in which Framatome demonstrated 
that the effectiveness of the ECCS will not be affected by a change 
from zircaloy to M5. The analysis described in the TR also demonstrated 
that the ECCS acceptance criteria applied to reactors fueled with 
zircaloy fuel rod cladding are also applicable to reactors fueled with 
M5 fuel rod cladding.
    The underlying purpose of 10 CFR Part 50, Appendix K, paragraph 
I.A.5, is to ensure that cladding oxidation and hydrogen generation are 
appropriately limited during a LOCA and conservatively accounted for in 
the ECCS evaluation model. Appendix K requires that the Baker-Just 
equation be used in the ECCS evaluation model to determine the rate of 
energy release, cladding oxidation, and hydrogen generation. In TR BAW-
10227P, Framatome demonstrated that the Baker-Just model is 
conservative in all post-LOCA scenarios with respect to the use of the 
M5 advanced alloy as a fuel rod cladding material or in other assembly 
structural components, and that the amount of hydrogen generated in an 
M5 core during a LOCA will remain within the FCS design basis.
    The M5 alloy is a proprietary zirconium-based alloy comprised of 
primarily zirconium (~99 percent) and niobium (~1 percent). The 
elimination of tin has resulted in superior corrosion resistance and 
reduced irradiation-induced growth relative to both standard zircaloy 
(1.7 percent tin) and low-tin zircaloy (1.2 percent tin). The addition 
of niobium increases ductility, which is desirable to avoid brittle 
failures.
    The NRC staff has reviewed the licensee's advanced cladding 
material, M5, for PWR fuel mechanical designs as described in TR BAW-
10227P. In the safety evaluation for TR BAW-10227P dated February 4, 
2000, the NRC staff concluded that, to the extent specified in the NRC 
staff's evaluation, the M5 properties and mechanical design methodology 
are acceptable for referencing in fuel reload licensing applications. 
Therefore, since the underlying purposes of 10 CFR 50.46 and 10 CFR 
Part 50, Appendix K, paragraph I.A.5 are achieved through the use of 
the M5 advanced alloy as a fuel rod cladding material or in other 
assembly structural components, the special circumstances required by 
10 CFR 50.12(a)(2)(ii) for the granting of an exemption from 10 CFR 
50.46 and 10 CFR Part 50, Appendix K, exist.

Summary

    The NRC staff has reviewed the licensee's request to use the M5 
advanced alloy for fuel rod cladding and in other assembly structural 
components in lieu of zircaloy or ZIRLO. Based on the NRC staff's 
evaluation, as set forth above, the NRC staff concludes that the 
exemption is authorized by law, will not present an undue risk to 
public health and safety, and is consistent with the common defense and 
security. In addition, the NRC staff concludes that the underlying 
purposes of 10 CFR 50.46 and 10 CFR Part 50, Appendix K, are achieved 
through the use of the M5 advanced alloy. Therefore, pursuant to 10 CFR 
50.12(a), the NRC staff concludes that the use of the M5 advanced alloy 
for fuel rod cladding and in other assembly structural components is 
acceptable and the exemption from 10 CFR 50.46 and 10 CFR Part 50, 
Appendix K, is justified.

4.07 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

[[Page 50477]]

the public health and safety, and is consistent with the common defense 
and security. Also, special circumstances are present. Therefore, the 
Commission hereby grants OPPD an exemption from the requirements of 10 
CFR 50.46 and 10 CFR Part 50, Appendix K, for the Fort Calhoun Station, 
Unit 1.
    Pursuant to 10 CFR 51.32, the Commission has determined that the 
granting of this exemption will not have a significant impact on the 
quality of the human environment (71 FR 46927; published on August 15, 
2006). This exemption is effective upon issuance.

    Dated at Rockville, Maryland, this 17th day of August 2006.

    For the Nuclear Regulatory Commission.
Catherine Haney,
Director, Division of Operating Reactor Licensing, Office of Nuclear 
Reactor Regulation.
 [FR Doc. E6-14106 Filed 8-24-06; 8:45 am]
BILLING CODE 7590-01-P