[Federal Register Volume 66, Number 93 (Monday, May 14, 2001)]
[Notices]
[Pages 24409-24410]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 01-12035]


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NUCLEAR REGULATORY COMMISSION

[Docket No. 50-289]


Amergen Energy Company, LLC, Three Mile Island Nuclear Station, 
Unit 1; Exemption

1.0  Background

    AmerGen Energy Company, LLC (the licensee or AmerGen) is the holder 
of Facility Operating License No. DPR-50 which authorizes operation of 
the Three Mile Island Nuclear Station, Unit 1 (TMI-1). The license 
provides, among other things, that the facility is subject to all 
rules, regulations, and orders of the U.S. Nuclear Regulatory 
Commission (NRC, the Commission) now or hereafter in effect.
    The facility consists of a pressurized-water reactor located in 
Dauphin County in Pennsylvania.

2.0  Purpose

    Title 10 of the Code of Federal Regulations (10 CFR), Part 50, 
Section 50.44, ``Standards for combustible gas control system in light-
water-cooled power reactors,'' requires, among other items, that each 
boiling or pressurized light-water nuclear power reactor fueled with 
oxide pellets within cylindrical zircaloy or ZIRLO cladding must, as 
provided in paragraphs (b) through (d) of that section, include means 
for control of hydrogen gas that may be generated, following a 
postulated loss-of-coolant accident (LOCA) by--(1) Metal-water reaction 
involving the fuel cladding and the reactor coolant, (2) Radiolytic 
decomposition of the reactor coolant, and (3) Corrosion of metals.
    Section 50.46, ``Acceptance criteria for emergency core cooling 
systems for light-water nuclear power reactors,'' requires, among other 
items, that each 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 LOCAs conform to the criteria set 
forth in paragraph (b) of that section. ECCS cooling performance must 
be calculated in accordance with an acceptable evaluation model and 
must be

[[Page 24410]]

calculated for a number of postulated LOCAs of different sizes, 
locations, and other properties sufficient to provide assurance that 
the most severe postulated LOCAs are calculated.
    Appendix K of 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 (Baker, L., Just, L.C., ``Studies of 
Metal Water Reactions at High Temperatures, III. Experimental and 
Theoretical Studies of the Zirconium-Water Reaction,'' ANL-6548, page 
7, May 1962) and implicitly assumes that either zircaloy or ZIRLO shall 
be used as the fuel rod cladding material.
    Sections 50.44, and 50.46, and Appendix K of 10 CFR Part 50, make 
no provisions for use of fuel rods clad with other than zircaloy or 
ZIRLO. The licensee has requested the use of Framatome Cogema Fuels 
(FCF) ``M5'' advanced alloy for fuel rod cladding for the TMI-1 Cycle 
14 operation. In order to accommodate the high fuel rod burnups that 
are required for today's modern fuel management schemes and core 
designs, FCF developed the M5 advanced fuel rod cladding and fuel 
assembly structural material. 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 
resistence and reduced irradiation induced growth relative to both 
standard Zircaloy and low-tin Zircaloy. The addition of niobium 
increases ductility. Since the chemical composition of the M5 alloy 
differs from the specifications of Zircaloy or ZIRLO, a plant-specific 
exemption is required to allow the use of the M5 alloy as a fuel rod 
cladding material at TMI-1. The M5 would also be used for fuel assembly 
spacer grids, fuel rod end plugs and fuel assembly guide and instrument 
tubes.

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. Special circumstances are 
present whenever application of the regulations 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.
    The underlying purpose of Section 50.46 is to ensure that 
facilities have adequate acceptance criteria for ECCS. FCF demonstrated 
in its topical report, BAW-10227P-A, ``Evaluation of Advanced Cladding 
and Structural Material (M5) in PWR Reactor Fuel,'' dated September 30, 
1997, and approved on February 4, 2000, that the effectiveness of the 
ECCS will not be affected by a change from zircaloy fuel rod cladding 
to M5 fuel rod cladding. The analysis described in BAW-10227P-A also 
concludes that the ECCS acceptance criteria applied to reactors fueled 
with zircaloy fuel are also applicable to reactors fueled with M5 fuel 
rod cladding.
    The underlying purposes of Section 50.44 and Appendix K, paragraph 
I.A.5, are to ensure that cladding oxidation and hydrogen generation 
are appropriately limited during a LOCA and conservatively accounted 
for in the ECCS evaluation model. Specifically, 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 BAW-10227P-A, FCF demonstrated that the Baker-Just model 
is conservative in all post-LOCA scenarios with respect to the use of 
M5 advanced alloy as fuel rod cladding material. The licensee has 
stated that the amount of hydrogen generated in an M5-clad core will 
remain within the TMI-1 design basis. The NRC staff has reviewed the 
FCF's advanced cladding and structural material, M5, for pressurized 
water reactor fuel mechanical designs as described in BAW-10227P-A. In 
its February 4, 2000, safety evaluation, the NRC staff concluded that, 
to the extent specified and with limitations noted in the NRC staff's 
evaluation, the assumptions related to M5 material properties and 
mechanical design methodology are acceptable for referencing in fuel 
reload licensing applications. The NRC staff has determined that since 
the licensee and FCF have ongoing processes which assure that LOCA 
analysis input values for peak cladding temperature-sensitive 
parameters bound the as-operated plant values for those parameters at 
TMI-1 and also have ongoing processes to determine mixed-core penalties 
as needed, the methodologies and analyses described in BAW-10227P-A 
apply to TMI-1 and the plant can be safely operated within the bounds 
of those analyses with mixed- and full-core loadings of M5 clad fuel 
and other M5 core structures. The NRC staff further concluded that 
since fuel assemblies which utilize the two different alloys (M5 and 
zircaloy) and which will be co-resident in the core have only slight 
geometry differences, there will be virtually no thermal-hydraulic 
effect, and a mixed core penalty in LOCA evaluations would not have to 
be assessed to compensate for the material differences. Therefore, 
based on the information described above, the NRC staff has determined 
that the underlying purposes of Section 50.44, and 50.46, and Appendix 
K of 10 CFR Part 50 have been achieved through the use of M5 advanced 
alloy as fuel rod cladding material and core structure material, and 
that the special circumstances required by 10 CFR 50.12(a)(2)(ii) for 
granting exemptions from 50.44, and 50.46, and Appendix K of 10 CFR 
Part 50 exist.

4.0  Conclusion

    Accordingly, the Commission has determined that, pursuant to 10 CFR 
50.12(a)(ii), the exemption is authorized by law, will not endanger 
life or property or common defense and security, and is, otherwise, in 
the public interest. Also, special circumstances are present. 
Therefore, the Commission hereby grants AmerGen Energy Company, LLC, an 
exemption from the requirements of 10 CFR 50.44, 10 CFR 50.46, and 
Appendix K to 10 CFR Part 50, for Three Mile Island Nuclear Station, 
Unit 1, as to the use of M5 cladding and core structures in lieu of 
Zircaloy or ZIRLO as currently specified or implied in those 
regulations.
    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 (66 FR 23279).
    This exemption is effective upon issuance.

    Dated at Rockville, Maryland, this 8th day of May 2001.

    For the Nuclear Regulatory Commission.
John A. Zwolinski,
Director, Division of Licensing Project Management, Office of Nuclear 
Reactor Regulation.
[FR Doc. 01-12035 Filed 5-11-01; 8:45 am]
BILLING CODE 7590-01-P