[Federal Register Volume 69, Number 150 (Thursday, August 5, 2004)]
[Notices]
[Pages 47465-47467]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 04-17853]
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NUCLEAR REGULATORY COMMISSION
[Docket No. 50-382]
Entergy Operations, Inc., Waterford Steam Electric Station, Unit
No. 3; Exemption
1.0 Background
Entergy Operations, Inc. (Entergy or the licensee) is the holder of
Facility Operating License No. NPF-38 which authorizes operation of
Waterford Steam Electric Station, Unit 3 (Waterford 3). 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 or the Commission) now or hereafter in effect. The
facility consists of a pressurized water reactor located in St. Charles
Parish, Louisiana.
2.0 Request/Action
Pursuant to title 10 of the Code of Federal Regulations (10 CFR)
section 50.12, ``Specific Exemptions,'' Entergy, in a letter dated
April 30, 2004, as supplemented by letter dated June 8, 2004, requested
an exemption to 10 CFR 50.46, ``Acceptance Criteria for Emergency Core
Cooling Systems for Light-Water Nuclear Power Reactors'', and Appendix
K to 10 CFR part 50, ``ECCS Evaluation Models.'' The regulation in 10
CFR 50.46 contains acceptance criteria for the emergency core cooling
system (ECCS) for reactors fueled with zircaloy or ZIRLO\TM\ cladding.
Appendix K to 10 CFR part 50 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. This 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
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cladding. Thus, an exemption from the requirements of 10 CFR 50.46 and
Appendix K to 10 CFR part 50 is needed to irradiate lead test
assemblies (LTAs) comprised of a developmental alloy (Optimized
ZIRLO\TM\) at Waterford 3.
3.0 Discussion
3.1 Material Evaluation
3.1.1 Fuel Mechanical Design
Tin is a solid solution strengthener and [alpha]-phase stabilizer
present entirely in the base [alpha]-phase zirconium crystalline
structure. Potential impacts of a reduced tin content on material
properties include: (1) A reduced tensile strength; (2) an increased
thermal creep rate; (3) an increased irradiation growth rate; (4) a
reduced [alpha] [rtarr][alpha]+[beta] phase transition temperature; and
(5) an improved corrosion resistance. The stated reduction in tin
content of Optimized ZIRLO\TM\ will not affect the size, shape, or
distribution of any second-phase or inter-metallic precipitates nor the
overall microstructure of this developmental zirconium alloy. With a
consistent microstructure, Optimized ZIRLO\TM\ will exhibit many
material characteristics similar to those of the licensed ZIRLO\TM\.
In response to a Request for Additional Information (RAI), Entergy
provided details of the planned post-irradiation examinations of the
LTAs. Measured parameters include rod profilometry, rod wear, assembly
and rod growth, assembly bow, grid cell dimensions, and oxide
thickness. As a result of these post-irradiation examinations, any
negative aspects of the low tin alloy's performance, including the
potential impacts of a reduced tin content identified above, will be
identified and resolved. Furthermore, significant deviations from model
predictions will be reconciled.
The fuel rod burnup and fuel duty experienced by the LTAs in
Waterford 3 will remain well within the operating experience base and
applicable licensed limits for ZIRLO\TM\.
Utilizing currently-approved fuel performance and fuel mechanical
design models and methods, Entergy and Westinghouse Electric
Corporation (Westinghouse) will perform cycle-specific reload
evaluations to ensure that the LTAs satisfy design criteria.
Based upon LTA irradiation experience of similar low tin versions
of ZIRLO\TM\, expected performance due to similar material properties,
and an extensive LTA post-irradiation examination program aimed at
qualifying model predictions, the NRC staff finds the LTA mechanical
design acceptable for Waterford 3.
3.1.2 Core Physics and Safety Analysis
The Waterford 3 exemption request relates solely to the specific
types of cladding material specified in the regulations. Due to similar
material properties, any impact of Optimized ZIRLO\TM\ on the safety
analysis models and methods is expected to be minimal. Utilizing
currently-approved core physics, core thermal-hydraulics, and non-loss-
of-coolant accident (LOCA) safety analysis models and methods, Entergy
and Westinghouse will perform cycle-specific reload evaluations to
ensure that the LTAs satisfy design criteria.
Fuel management guidelines will require that LTAs be placed in non-
limiting core locations. In response to an RAI, Entergy described how
power-peaking margins would be used to ensure that LTAs will not be
limiting.
Based upon the use of approved models and methods, expected
material performance, and the placement of LTAs in non-limiting core
locations, the NRC staff finds that the irradiation of up to four LTAs
in Waterford 3 will not result in unsafe operation or violation of
specified acceptable fuel design limits. Furthermore, in the event of a
design-basis accident, these LTAs will not promote consequences beyond
those currently analyzed. Based upon results of metal-water reaction
tests and ring-compression tests, which ensure the applicability of
ECCS models and acceptance criteria and the use of approved LOCA models
to ensure that the LTAs satisfy 10 CFR 50.46 acceptance criteria, the
NRC staff considers the LTAs acceptable for use at Waterford 3 as
proposed by Entergy.
3.2 Regulatory Evaluation
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 if: (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) special circumstances are present.
3.2.1 10 CFR 50.46
The underlying purpose of 10 CFR 50.46 is to establish acceptance
criteria for ECCS performance. The applicability of the ECCS acceptance
criteria has been demonstrated by Westinghouse. Ring-compression tests
performed by Westinghouse on Optimized ZIRLO\TM\ (documented in
Appendix B of Addendum 1 to WCAP-12610-P-A) demonstrate an acceptable
retention of ductility up to 10 CFR 50.46 limits of 2200 [deg]F and 17
percent Equivalent Cladding Reacted.
Utilizing currently approved LOCA models and methods, Westinghouse
will perform cycle-specific reload evaluations to ensure that the LTAs
satisfy 10 CFR 50.46 acceptance criteria. Therefore, granting the
proposed exemption will not defeat the underlying purpose of 10 CFR
50.46.
3.2.2 10 CFR Part 50, Appendix K
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 LTA cladding for determining acceptable fuel
performance. Metal-water reaction tests performed by Westinghouse on
Optimized ZIRLO\TM\ (documented in Appendix B of Addendum 1 to WCAP-
12610-P-A) demonstrate conservative reaction rates relative to the
Baker-Just equation. Therefore, granting the proposed exemption will
not defeat the underlying purpose of Appendix K, Paragraph I.A.5.
3.2.3 Special Circumstances
In summary, the NRC staff reviewed the licensee's request of
proposed exemption to allow up to four LTAs containing fuel rods
fabricated with Optimized ZIRLO\TM\. Based on the NRC staff's
evaluation, as set forth above, the NRC staff considers that granting
the proposed exemption will not defeat the underlying purpose of 10 CFR
50.46 or Appendix K to 10 CFR Part 50. Accordingly, special
circumstances, are present pursuant to 10 CFR 50.12(a)(2)(ii).
3.2.4 Other Standards in 10 CFR 50.12
The staff examined the rest of the licensee's rationale to support
the exemption request, and concluded that the use of Optimized
ZIRLO\TM\ would satisfy 10 CFR 50.12(a) as follows:
(1) The requested exemption is authorized by law:
No law precludes the activities covered by this exemption request.
The Commission, based on technical reasons set forth in rulemaking
records, specified the specific cladding materials identified in 10 CFR
50.46 and 10 CFR part 50, Appendix K. Cladding materials are not
specified by statute.
(2) The requested exemption does not present an undue risk to the
public
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health and safety as stated by the licensee:
The LTA reload evaluation will ensure that these acceptance
criteria [in the Commission's regulations] are met following the
insertion of LTAs containing Optimized ZIRLO\TM\ material. Fuel
assemblies using Optimized ZIRLO\TM\ cladding will be evaluated
using NRC-approved analytical methods and plant specific models to
address the changes in the cladding material properties. The safety
analysis for Waterford 3 is supported by the applicable Technical
Specifications. The Waterford 3 reload cores containing Optimized
ZIRLO\TM\ cladding are required to be operated in accordance with
the operating limits specified in the Technical Specifications. The
LTAs utilizing Optimized ZIRLO\TM\ cladding will be placed in non-
limiting core locations. Thus, the granting of this exemption
request will not pose an undue risk to public health and safety.
The NRC staff has evaluated these considerations as set forth in
Section 3.1 of this exemption. For the reasons set forth in that
section, the NRC staff concludes that Optimized ZIRLO\TM\ may be used
as a cladding material for no more than four LTAs to be placed in non-
limiting core locations during Waterford 3's next refueling outage, and
that an exemption from the requirements of 10 CFR 50.46 and 10 CFR part
50, Appendix K does not pose an undue risk to the public health and
safety.
(3) The requested exemption will not endanger the common defense
and security:
The common defense and security are not affected and, therefore,
not endangered by this exemption.
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 Entergy an exemption from the
requirements of 10 CFR 50.46 and 10 CFR part 50, Appendix K, to allow
the use of Optimized ZIRLO\TM\ as a cladding material in four LTAs in
the capacity described in their April 30, 2004, submittal, as
supplemented by letter dated June 8, 2004, up to a lead rod average
burnup of 60,000 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 (69 FR 31848 dated June 7, 2004).
This exemption is effective upon issuance.
Dated in Rockville, Maryland, this 28th day of July, 2004.
For the Nuclear Regulatory Commission.
James E. Lyons,
Deputy Director, Division of Licensing Project Management, Office of
Nuclear Reactor Regulation.
[FR Doc. 04-17853 Filed 8-4-04; 8:45 am]
BILLING CODE 7590-01-P