Southern Nuclear Operating Company, Inc.; Edwin I. Hatch Nuclear Plant, Units 1 and 2; Exemption, 8738-8740 [2014-03215]

Agencies

• NUCLEAR REGULATORY COMMISSION

[Federal Register Volume 79, Number 30 (Thursday, February 13, 2014)]
[Notices]
[Pages 8738-8740]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2014-03215]


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NUCLEAR REGULATORY COMMISSION

[Docket Nos. 50-321 and 50-366; NRC-2008-0585]


Southern Nuclear Operating Company, Inc.; Edwin I. Hatch Nuclear 
Plant, Units 1 and 2; Exemption

1.0 Background

    The Southern Nuclear Operating Company, Inc. (SNC, the licensee) is 
the holder of the Renewed Facility Operating License Nos. DPR-57 and 
NPF-5 which authorize operation of the Edwin I. Hatch Nuclear Plant, 
Units 1 and 2 (HNP). The licenses provide, among other things, that the 
facility is subject to the rules, regulations, and orders of the U.S. 
Nuclear Regulatory Commission (NRC) now or hereafter in effect.
    The HNP facility consists of two boiling-water reactors located in 
Appling County, Georgia.

2.0 Request/Action

    Pursuant to Sec.  50.12 of Title 10 of the Code of Federal 
Regulations (10 CFR), Specific Exemptions, SNC has, by letter dated 
April 23, 2013, requested an exemption from the fuel cladding material 
requirements in 10 CFR 50.46, ``Acceptance criteria for emergency core 
cooling systems [ECCS] for light-water nuclear power reactors,'' and 
Appendix K to 10 CFR Part 50, ``ECCS Evaluation Models,'' (Appendix K).
    The SNC's letter of April 23, 2013, constitutes the licensee's 
second request for an exemption from the above fuel cladding material 
requirements in order to irradiate two GE14 Lead Test Assemblies (LTAs) 
in the HNP. The LTAs include a limited number of fuel rods manufactured 
with an advanced cladding alloy, known as Global Nuclear Fuel (GNF) 
Ziron, which is outside of the cladding materials specified in the 
regulations (i.e. zircaloy or ZIRLO\TM\). By letter dated November 7, 
2008, the NRC approved an earlier SNC request for an exemption in order 
to irradiate these two GE14 LTAs in the HNP Unit 2 reactor for cycles 
21, 22 and 23. These two LTAs have now completed operation in cycles 21 
and 22; however, SNC decided not to include them in the Unit 2 cycle 23 
core loading in order to allow sufficient time to perform pool-side 
inspections. Since the original exemption request applied only to the 
operation of the LTAs in the Unit 2 reactor for cycles 21-23, SNC has 
requested a second exemption in order to continue irradiation of the 
LTAs in either of the HNP reactors for one or more additional cycles, 
up to GNF's approved peak pellet exposure.

[[Page 8739]]

    The regulation in 10 CFR 50.46 contains acceptance criteria for an 
ECCS for reactors fueled with zircaloy or ZIRLO\TM\ cladding. In 
addition, Appendix K requires that the Baker-Just equation be used to 
predict the rates of energy release, hydrogen concentration, and 
cladding oxidation from the metal-water reaction. The exemption request 
relates solely to the specific types of cladding material specified in 
these regulations. As written, the regulations presume the use of 
zircaloy or ZIRLO\TM\ fuel rod cladding. Thus, an exemption from the 
requirements of 10 CFR 50.46, and Appendix K is needed to irradiate a 
lead test assembly (LTA) comprised of different cladding alloys at HNP.

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 the public health 
and safety, and are consistent with the common defense and security; 
and (2) when special circumstances are present. Under 10 CFR 
50.12(a)(2), special circumstances include, among other things, when 
application of the regulation in the particular circumstances 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 insert two lead test 
fuel assemblies with fuel rod cladding that does not meet the 
definition of zircaloy or ZIRLO\TM\, as specified by 10 CFR 50.46, and 
Appendix K, in either of the HNP reactors for one or more additional 
cycles, up to GNF's approved peak pellet exposure. 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

    In regard to the fuel mechanical design, the exemption request 
relates solely to the specific types of cladding material specified in 
the regulations. The underlying purpose of 10 CFR 50.46 is to establish 
acceptance criteria for ECCS. In Section VI of its letter dated April 
23, 2013, SNC provides a technical basis supporting the applicability 
of the 50.46 Paragraph (b) fuel criteria to GNF-Ziron. Experimental 
results from tests conducted on GNF-Ziron samples exposed to loss-of-
coolant accident (LOCA) conditions were provided by SNC. While these 
tests differ from the post-steam oxidized ring-compression testing 
(which forms the basis of the 10 CFR 50.46 post-quench ductility 
criteria), these results provide reasonable assurance that the 17 
percent oxidation and 2200 degree Farenheit criteria are valid for GNF-
Ziron and meet the underlying purpose of the rule, which is to maintain 
a degree of post-quench ductility in the fuel cladding material.
    As discussed in the NRC Research Information Letter 0801, 
``Technical Basis for Revision of Embrittlement Criteria in 10 CFR 
50.46,'' ADAMS Accession No. ML081350225, based on an ongoing LOCA 
research program at Argonne National Laboratory, cladding corrosion 
(and associated hydrogen pickup) has a significant impact on post-
quench ductility. Post-irradiation examinations provided by the 
licensee demonstrate the favorable hydrogen pickup characteristics of 
GNF-Ziron as compared with standard zircaloy. Hence, the GNF-Ziron fuel 
rods would be less susceptible to the detrimental effects of hydrogen 
uptake during normal operation and their impact on post-quench 
ductility.
    Paragraph I.A.5 of Appendix K to 10 CFR Part 50 states that the 
rate of energy release, hydrogen generation, 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 LTA cladding for determining acceptable fuel 
performance. Metal-water reaction tests performed by GNF on GNF-Ziron, 
as described in the application for exemption, demonstrate conservative 
reaction rates relative to the Baker-Just equation. Thus, application 
of Appendix K, Paragraph I.A.5 is not necessary for the licensee to 
achieve its underlying purpose in these circumstances.
    High temperature perforation test results were included in the 
application. These test results illustrate similar burst 
characteristics of GNF-Ziron as compared with standard zircaloy. In 
addition, the licensee provides further comparisons of material 
properties between GNF-Ziron and zircaloy. Based upon this comparison 
of material properties, GNF and SNC believe that currently approved 
methods and models are directly applicable to GNF-Ziron. Based upon the 
material properties provided in SNC's letter dated April 23, 2013, the 
NRC staff finds the use of current LOCA models and methods acceptable 
for the purpose of evaluating LTAs containing a limited number of GNF-
Ziron fuel rods. The staff notes that Section V of GNF's technical 
basis document (Enclosure 2 of the April 23, 2013 application) states 
that the GNF fuel rod thermal mechanical code PRIME03 is now being used 
to assess fuel rod performance. The PRIME03 code, which accounts for 
exposure-dependent fuel thermal conductivity, replaces the legacy 
GESTRM fuel rod performance code. While not explicitly approved for 
GNF-Ziron, the use of PRIME03 is consistent with the approved GNF 
reload methodology and therefore acceptable.
    Through the mechanical testing and a comparison of material 
properties provided by SNC, the staff has reasonable assurance that 
anticipated in-reactor performance will be acceptable. Further, the 
licensee has demonstrated that the use of current methods and models 
are reasonable for evaluating the cladding's performance in response to 
anticipated operational occurrences and accidents. Nevertheless, as 
with any developmental cladding alloy, the NRC staff requires a 
limitation on the total number of fuel rods clad in a developmental 
alloy in order to ensure a minimal impact on the simulated progression 
and calculated consequences of postulated accidents. This limitation is 
directly related to the available material properties (both 
unirradiated and irradiated) used to judge the cladding alloy's 
anticipated in-reactor performance. Based on the material properties 
data presented within the application attachments, the NRC staff finds 
the HNP LTA program acceptable with respect to achieving the underlying 
purpose of 10 CFR 50.46 and Appendix K to 10 CFR Part 50.
    Based upon results of metal-water reaction tests and mechanical 
testing which ensure the applicability of ECCS models and acceptance 
criteria, the limited number and anticipated performance of the 
advanced cladding fuel rods, and the use of approved LOCA models to 
ensure that the LTAs satisfy 10 CFR 50.46 acceptance criteria, the NRC 
staff finds it acceptable to grant an exemption from the requirements 
of 10 CFR 50.46 and Appendix K to 10 CFR Part 50 for the use of two 
LTAs in either of the HNP reactors for one or more additional cycles, 
up to GNF's approved peak pellet exposure.

[[Page 8740]]

Consistent With Common Defense and Security

    The proposed exemption would allow the licensee to insert two lead 
test fuel assemblies with fuel rod cladding that does not meet the 
definition of zircaloy or ZIRLO\TM\ as specified by 10 CFR 50.46, and 
Appendix K, into either of the HNP reactors for one or more additional 
cycles, up to GNF's approved peak pellet exposure. This change 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, 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 emergency core cooling system 
performance. The wording of the regulations in 10 CFR 50.46 and 
Appendix K is not directly applicable to Ziron, even though the 
evaluations discussed above show that the intent of the regulations is 
met. Therefore, since the NRC staff finds that the underlying purpose 
of 10 CFR 50.46 and Appendix K is achieved with the use of Ziron, the 
special circumstances required by 10 CFR 50.12 for the 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 SNC an exemption from the 
requirements of 10 CFR 50.46, and 10 CFR Part 50, Appendix K, to allow 
the limited use of two LTAs with selected rods clad with GNF-Ziron 
cladding in either of the HNP reactors for one or more additional 
cycles, up to GNF's approved peak pellet exposure.
    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 (79 FR 4983; January 30, 2014).
    This exemption is effective upon issuance.

    Dated at Rockville, Maryland, this 4th day of February 2014.

    For the Nuclear Regulatory Commission.
Michele G. Evans,
Director, Division of Operating Reactor Licensing, Office of Nuclear 
Reactor Regulation.
[FR Doc. 2014-03215 Filed 2-12-14; 8:45 am]
BILLING CODE 7590-01-P