[Federal Register Volume 67, Number 175 (Tuesday, September 10, 2002)]
[Notices]
[Pages 57461-57462]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 02-22915]


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NUCLEAR REGULATORY COMMISSION

[Docket No. 50-339]


Virginia Electric and Power Company, North Anna Power Station, 
Unit 2; Exemption

1.0 Background

    The Virginia Electric and Power Company (the licensee) is the 
holder of Facility Operating License No. NPF-7, which authorizes 
operation of the North Anna Power Station, Unit 2. 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 one pressurized-water reactor located in 
Louisa County in the Commonwealth of Virginia.

2.0 Request/Action

    Title 10 of the Code of Federal Regulations (10 CFR), part 50, 
Section 50.44 requires reactors fueled with Zircaloy or ZIRLO cladding 
to control any hydrogen gas that may be generated after a postulated 
loss-of-coolant accident (LOCA). 10 CFR 50.46 identifies design 
requirements for calculating the performance of the emergency core 
cooling system (ECCS) for reactors containing fuel with Zircaloy or 
ZIRLO cladding. Finally, Appendix K to 10 CFR part 50 requires the 
Baker-Just equation, which is only applicable for fuels using Zircaloy 
cladding, be used to predict the rates of energy release, hydrogen 
concentration, and cladding oxidation from the metal water reaction.
    By letter dated February 11, 2002, as supplemented by letter dated 
May 16, 2002, the licensee submitted a request for a license amendment 
to irradiate a Framatome lead test assembly during Cycle 16 at North 
Anna, Unit 2. The lead test assembly to be used is one of four lead 
test assemblies that have been used for the past three operating cycles 
at North Anna, Unit 1. Included in this proposed license amendment was 
a request for an exemption from the requirements of 10 CFR 50.44, 
50.46, and Appendix K to 10 CFR part 50 that would allow the licensee 
to use a lead test assembly that consisted of two advanced zirconium-
based alloys, M4 and M5, for the fuel rod cladding. The licensee 
included the following license condition in its submittal:

    Virginia Electric and Power Company may operate one lead test 
assembly containing advanced zirconium-based alloys for one cycle, to a 
lead rod burnup not exceeding 75,000 MWD/MTU.

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. In accordance with 10 CFR 
50.12(a)(2)(ii), special circumstances exist whenever an application of 
a particular regulation under the circumstances is not necessary to 
achieve the underlying purpose of the rule.
    The underlying purpose of 10 CFR 50.44 is to ensure that means are 
provided for the control of hydrogen gas that may be generated 
following a LOCA. The licensee has provided means for controlling 
hydrogen gas and has previously considered the potential for hydrogen 
gas generation stemming from a metal-water reaction. The chemical 
similarity of the lead test assembly containing advanced zirconium-
based cladding with that of the Zircaloy cladding ensures that previous 
calculations of hydrogen production resulting from a metal-water 
reaction would not be significantly changed. As such, the licensee has 
achieved the underlying purpose of 10 CFR 50.44.
    The underlying purpose of 10 CFR 50.46 and 10 CFR part 50, Appendix 
K, is to establish requirements for the calculation of ECCS 
performance. The licensee has performed a calculation demonstrating 
adequate ECCS performance for North Anna, Unit 2, and has shown that 
the lead test assembly does not have a significant impact upon the 
calculation. The peak cladding temperature of the lead test assembly 
was significantly lower than the resident Westinghouse fuel. Using the 
Baker-Just equation, the result conservatively predicted local cladding 
oxidation of the lead test assembly of only a few percent. Also, the 
maximum hydrogen generation was unchanged with the inclusion of the 
lead test assembly. Therefore, the coolable geometry was maintained 
following a LOCA.
    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 advanced zirconium-based alloys for determining acceptable 
fuel performance. The underlying intent of this portion of the 
Appendix, however, is to ensure that analysis of fuel response to LOCAs 
is conservatively calculated. Due to the similarities in the chemical 
composition of the advanced zirconium-based alloys and Zircaloy, the 
application of the Baker-Just equation in the analysis of advanced 
zirconium-based clad fuel is justified and will conservatively bound 
all post-LOCA scenarios. Thus the underlying purpose of the rule will 
be met, and special circumstances exist, allowing the staff to grant an 
exemption from Appendix K to 10 CFR Part 50 that would allow the 
licensee to apply the Baker-Just equation to advanced zirconium-based 
alloys.
    The staff confirmed that the licensee used approved LOCA methods to

[[Page 57462]]

perform the calculations that demonstrated adequate safety performance 
of ECCS systems. These methods include: (1) RSG LOCA-BWNT LOCA 
evaluation model (BAW-10168, Rev. 3), (2) RELAP5/MOD2-B&W code (BAW-
10164, Rev. 3), (3) the BEACH implementation of RELAP5 (BAW-10166, Rev. 
4), and (4) REFLOD3B (BAW-10171-PA, Rev. 3). The licensee documented 
calculations based on these models to demonstrate that existing North 
Anna calculations based on the current fuel design conservatively bound 
the LOCA performance of the lead test assembly as calculated by the 
NRC-approved methods. Results of comparative LOCA calculations with the 
same plant operating parameters demonstrated that the LOCA 
calculational methods used are acceptable for the lead test assembly at 
North Anna, Unit 2. Therefore, the licensee has achieved the underlying 
purpose of 10 CFR 50.46 and 10 CFR Part 50, Appendix K.
    The lead test assembly meets the same design bases and requirements 
as the resident Westinghouse fuel for the North Anna, Unit 2, Cycle 16 
core. No safety limits or setpoints have been altered as a result of 
the use of the lead test assembly. The lead test assembly will be 
placed in a core location that will not experience the most limiting 
power peaking during the aforementioned operating cycle. The advanced 
cladding has been irradiated and tested for corrosion resistance, 
tensile and burst strength, and creep characteristics. The results 
indicate that the advanced cladding should be acceptable for reactor 
service. Therefore, granting the exemption requests will not present an 
undue risk to public health and safety or be inconsistent with the 
common defense and security.
    Based on the previously acceptable performance of the four lead 
test assemblies at North Anna, Unit 1, and the subsequent approval of 
the advanced cladding material M5, the staff concludes that the 
licensee has demonstrated that the lead test assembly will perform 
adequately under LOCA conditions, and thus the lead test assembly is 
acceptable for operation in North Anna, Unit 2, Cycle 16. In addition, 
based on the special circumstances described above, the staff approves 
of an exemption from the requirements of 10 CFR 50.44, 10 CFR 50.46, 
and 10 CFR Part 50 Appendix K for the lead test assembly in North Anna, 
Unit 2.

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 50.44, 10 CFR 50.46, and Appendix K to 10 
CFR Part 50, for North Anna Power Station, Unit 2. This exemption only 
applies to the one lead test assembly containing advanced zirconium-
based alloys for the one operating cycle, with a lead rod burnup not 
exceeding 75,000 MWD/MTU.
    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 (67 FR 53813).
    This exemption is effective upon issuance.

    Dated at Rockville, Maryland, this 4th day of September 2002.

    For the Nuclear Regulatory Commission.
John A. Zwolinski,
Director, Division of Licensing Project Management, Office of Nuclear 
Reactor Regulation.
[FR Doc. 02-22915 Filed 9-9-02; 8:45 am]
BILLING CODE 7590-01-P