6564 Federal Register / Vol. 62, No. 29 / Wednesday, February 12, 1997 / Notices

NUCLEAR REGULATORY

COMMISSION

[Docket No. STN 50–530]

Arizona Public Service Company, et

al., (Palo Verde Nuclear Generating

Station, Unit 3); Exemption

I.

On November 25, 1987, the

Commission issued Facility Operating

License No. NPF–74 to Arizona Public

Service Company, Salt River Project

Agricultural Improvement and Power

District, El Paso Electric Company,

Southern California Edison Company,

Public Service Company of New

Mexico, Los Angeles Department of

Water and Power, and Southern

California Public Power Authority for

the Palo Verde Nuclear Generating

Station, Unit 3. The license provides,

among other things, that the licensee is

subject to all rules, regulations, and

orders of the Commission now or

hereafter in effect.

II.

Several sections of Title 10 of the

Code of Federal Regulations discuss

requirements for fuel that is used in

light water nuclear power reactors.

Since these requirements refer to

specific cladding types of zircaloy or

ZIRLO, the use of fuel clad with other

zirconium-based alloys, or any other

cladding material, that do not conform

to these two designations requires an

exemption from the code.

Specifically, 10 CFR 50.44,

‘‘[s]tandards for combustible gas control

system in light-water-cooled power

reactors,’’ contains requirements for the

control of hydrogen gas that may be

generated after a postulated loss-ofcoolant accident in light-water nuclear

power reactors fueled with uranium

oxide pellets within cylindrical zircaloy

or ZIRLO cladding. Section 50.46 of

Title 10 of the Code of Federal

Regulations, ‘‘[a]cceptance criteria for

emergency core cooling systems for light

water nuclear power reactors,’’ contains

acceptance criteria for emergency core

cooling systems (ECCS) for light-water

nuclear power reactors fueled with

uranium oxide pellets within

cylindrical zircaloy or ZIRLO cladding.

Appendix K to Part 50, ‘‘ECCS

Evaluation models,’’ contains the

required and acceptable features for

ECCS evaluation models to meet the

requirements of 10 CFR 50.46.

Paragraph I.A.5 of Appendix K states

that the rates of energy release,

hydrogen concentration, and cladding

oxidation from the metal-water reaction

shall be calculated using the Baker-Just

equation. The Baker-Just equation

presumes the use of Zircaloy or ZIRLO

clad fuel.

Testing of advanced clad materials is

necessary to provide data to justify fullcore use of clad materials and a

subsequent rule change to implement

the advanced clad designs.

III.

By letter dated September 12, 1996, as

supplemented by letter dated December

13, 1996, Arizona Public Service

Company (APS, or the licensee),

submitted a request for exemption from

the requirements of 10 CFR 50.44, 10

CFR 50.46, and Appendix K to Part 50,

to allow use of three lead fuel

assemblies (LFAs) that contain

advanced zirconium-based cladding

materials. These assemblies would be

used to evaluate the performance of the

advanced cladding materials for three

fuel cycles, which are cycles 7, 8, and

9.

Pursuant to 10 CFR 50.12(a), ‘‘[t]he

Commission may, upon application by

any interested person or upon its own

initiative, grant exemptions from the

requirements of the regulations of this

part, which are—(1) Authorized by law,

will not present an undue risk to the

public health and safety, and are

consistent with the common defense

and security. (2) The Commission will

not consider granting an exemption

unless special circumstances are

present. Special circumstances are

present whenever—* * * (ii)

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 * * *’’.

As discussed in Section II. above, three

separate sections of Title 10 to the Code

of Federal Regulations establish

requirements for performance of fuel

used in light-water nuclear power

reactors. These regulations refer to the

use of zircaloy or ZIRLO cladding

material, but do not specify what

constitutes zircaloy. Therefore, the use

of fuel that is clad with other zirconiumbased alloys may not be within the

regulatory basis for use of other alloys

and would, in effect, place the licensee

outside the applicability of these

sections of the code. The licensee would

require an exemption to these portions

of the code to allow use of advanced

zirconium-based alloys in its reactor.

The information provided by the

licensee in its September 12, 1996, letter

demonstrates that the predicted

chemical, mechanical, and material

performance characteristics of the

advanced zirconium-based cladding is

within the parameters approved for

zircaloy under anticipated operations

occurrences and postulated accidents.

In addition, nominal fuel performance

characteristics of the advanced

zirconium-based clad test rods continue

to be the same as, or superior to, those

experienced with existing Zircaloy-4

fuel rods. The information provided in

the licensee’s December 13, 1996, letter

demonstrated that although two of the

three proposed lead fuel assemblies will

be in relatively high power and rodded

positions during Unit 3 Cycle 7, these

assemblies will not be in limiting (the

highest power) regions of the core. The

licensee also proposes to include up to

six fuel rods that have already been

exposed for three fuel cycles in one of

the three fuel assemblies. These rods are

being tested to determine the effects on

the cladding of extended burnup. These

rods will be measured after Cycle 6, and

before use in Cycle 7, to ensure that end

of cycle (EOC) 7 maximum

circumferentially averaged oxide

thickness projected for each rod

transferred will remain below the

approved oxide thickness limit, and that

adequate shoulder gap will exist at EOC

7 for each rod using conservative

assumptions for fuel rod and fuel

assembly growth. The staff concludes

that the use of advanced zirconiumbased cladding materials in three lead

fuel assemblies in non-limiting core

locations will not present an undue risk

to the public health and safety, and is

consistent with the common defense

and security.

The underlying purpose of 10 CFR

50.44 is to ensure that adequate means

is provided for the control of hydrogen

gas that may be generated following a

loss of coolant accident (LOCA). The

hydrogen produced in a post-LOCA

scenario comes from cladding oxidation

in a metal-water reaction. Most of the

high temperature oxidation occurs

during that portion of the LOCA

scenario that results in a molecular

phase of zirconium (the beta-phase) that

allows a significantly higher diffusion

coefficient for oxygen than that

molecular phase of zirconium that exists

during normal operation (the alphaphase). The beta-phase oxidation

resistance of the proposed alloys is

expected to be as good as, or better than,

that of the existing Zircaloy–4. In

addition, the elemental composition

used in the proposed alloy to improve

the corrosion resistance of the alphaphase of these alloys will also improve

the corrosion resistance of the betaphase of these alloys as well. The staff

therefore concludes that the beta-phase

oxidation rate of the proposed alloys

will be at or lower than that of the
Federal Register / Vol. 62, No. 29 / Wednesday, February 12, 1997 / Notices 6565

existing Zircaloy–4. A strict

interpretation of the rule in this instance

would conclude that the criteria of 10

CFR 50.44 are not met by advanced

zirconium-based alloys, since these

alloys are not specifically zircaloy or

ZIRLO. Since the advanced zirconiumbased alloys meet the underlying

purpose of the rule, strict application of

the rule to only apply to zircaloy or

ZIRLO cladding is not necessary to

achieve the underlying purpose of the

rule. Since strict application of 10 CFR

50.44 is not necessary to meet the

underlying purpose of the rule, special

circumstances exist to grant an

exemption from this regulation to allow

a reactor to contain three lead fuel

assemblies containing fuel rods clad

with advanced zirconium-based alloys.

The underlying purpose of 10 CFR

50.46 is to specify acceptance criteria

for ECCS performance at light-water

nuclear power reactors. The fuel rods

clad with the advanced zirconium-based

alloys will be identical in design and

dimensions to the fuel rods clad with

the existing Zircaloy–4. The advanced

cladding materials used in the proposed

fuel assemblies were chosen to improve

corrosion resistance exhibited in exreactor autoclave corrosion tests in both

high-temperature water and steam

environments. Fuel rods clad with

similar types of advanced zirconiumbased alloys have been successfully

irradiated in high-temperature PWRs in

Europe. The mechanical properties of

the advanced zirconium-based alloy

clad meets all the mechanical

requirements of the existing Zircaloy–4

procurement specifications. Thus the

cladding and structural integrity of the

fuel rods and fuel assemblies with

advanced zirconium-based alloy

cladding will be maintained. In

addition, although the staff has not yet

reviewed and generically approved the

overall behaviors of alloys A and F to

meet the limits of ECCS performance

criteria requirements, the three lead fuel

assemblies will be placed in nonlimiting locations within the core. Based

on the above considerations, the staff

concludes that the lead fuel assemblies

will perform acceptably under

postulated LOCA conditions. Thus, the

underlying purpose of the rule has been

met. A strict interpretation of the rule in

this instance would conclude that the

criteria of 10 CFR 50.46 are not met by

advanced zirconium-based alloys, since

these alloys are not strictly zircaloy or

ZIRLO. Since the advanced zirconiumbased alloys meet the underlying

purpose of the rule, strict application of

the rule to only apply to zircaloy or

ZIRLO cladding is not necessary to

achieve the underlying purpose of the

rule. Therefore, special circumstances

exist to grant an exemption from 10 CFR

50.46 that would allow the licensee to

apply the acceptance criteria of 10 CFR

50.46 to a reactor containing a limited

number of fuel rods with advanced

zirconium-based alloys.

Paragraph I.A.5 of Appendix K to 10

CFR Part 50 states that the rates of

energy release, hydrogen concentration,

and cladding oxidation from the metalwater 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

composition of the advanced zirconiumbased alloys and Zircaloy/ZIRLO, the

application of the Baker-Just equation in

the analysis of advanced zirconiumbased clad fuel will conservatively

bound all post-LOCA scenarios. Thus,

the underlying purpose of the rule will

be met. Thus, special circumstances

exist 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.

IV.

Accordingly, the Commission has

determined, pursuant to 10 CFR

50.12(a)(i), that an exemption as

described in Section III above 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. The

Commission has determined, pursuant

to 10 CFR 50.12(a)(2)(ii), that special

circumstances exist, as noted in Section

III above. Therefore, the Commission

hereby grants Arizona Public Service

Company, et al., an exemption from 10

CFR 50.44, 10 CFR 50.46, and Appendix

K to 10 CFR Part 50 for use of lead fuel

assemblies.

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 (62 FR 3925).

This exemption is effective upon

issuance.

For the Nuclear Regulatory Commission.

Dated at Rockville, Maryland this 4th day

of February 1997.

Frank J. Miraglia, Jr.,

Acting Director, Office of Nuclear Reactor

Regulation.

[FR Doc. 97–3463 Filed 2–11–97; 8:45 am]

BILLING CODE 7590–01–P

[Docket Nos. 50–315 and 50–316]

Indiana Michigan Power Company;

Donald C. Cook Nuclear Plant, Unit

Nos. 1 and 2 Environmental

Assessment and Finding of no

Significant Impact

The U.S. Nuclear Regulatory

Commission (the Commission) is

considering issuance of amendments to

Facility Operating License Nos. DPR–58

and DPR–74, issued to Indiana

Michigan Power Company, (the

licensee), for operation of the D. C. Cook

Nuclear Plant, Units 1 and 2, located in

Berrien County, Michigan.

Environmental Assessment

Identification of the Proposed Action

By letter dated February 26, 1996, the

licensee requested amendments to the

Technical Specifications (TS) to allow

an increased limit for the nominal

enrichment of new (unirradiated)

Westinghouse fabricated fuel stored in

the new fuel storage racks. The

proposed changes would allow for the

storage of fuel with an enrichment not

to exceed a nominal 4.95 weight percent

(w/o) U–235, subject to certain integral

fuel burnable absorber (IFBA)

requirements, in the new fuel storage

racks. Plant operation using the higher

enriched fuel will be demonstrated to be

acceptable by a cycle specific reload

safety evaluation performed prior to

each fuel loading.

Need for Proposed Action

The licensee intends to use higher

enrichment fuel in subsequent fuel load

cycles which does not currently meet

the new fuel storage limits in the TSs.

By increasing the fuel enrichment, the

licensee will implement the fuel

strategies developed for D.C. Cook Units

1 and 2.

Environmental Impact of the Proposed

Action

The Commission has completed its

evaluation of the proposed revision to

the TSs and concludes that storage of

fuel enriched with U–235 up to 4.95

weight percent at D.C. Cook Units 1 and

2 is acceptable. The safety

considerations associated with higher

enrichments have been evaluated by the

NRC staff and the staff has concluded