[Federal Register Volume 65, Number 105 (Wednesday, May 31, 2000)]
[Proposed Rules]
[Pages 34599-34602]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-13515]


=======================================================================
-----------------------------------------------------------------------

NUCLEAR REGULATORY COMMISSION

10 CFR Part 50

[Docket No. PRM-50-71]


Nuclear Energy Institute; Receipt of Petition for Rulemaking

AGENCY: Nuclear Regulatory Commission.

ACTION: Petition for rulemaking; Notice of receipt.

-----------------------------------------------------------------------

SUMMARY: The Nuclear Regulatory Commission (NRC) has received and 
requests public comment on a petition for rulemaking filed by the 
Nuclear Energy Institute. The petition was docketed on April 12, 2000, 
and has been assigned Docket No. PRM-50-71. The petitioner requests 
that the NRC amend its regulations to allow nuclear power plant 
licensees to use zirconium-based cladding materials other than zircaloy 
or ZIRLO, provided the cladding materials meet the requirements for 
fuel cladding performance and have received approval by the NRC staff. 
The petitioner believes the proposed amendment would improve the 
efficiency of the regulatory process by eliminating the need for 
individual licensees to obtain exemptions to use advanced cladding 
materials which have already been approved by the NRC.

DATES: Submit comments by August 14, 2000. Comments received after this 
date will be considered if it is practical to do so, but the Commission 
is able to assure consideration only for comments received on or before 
this date.

ADDRESSES: Mail comments to: Secretary, U.S. Nuclear Regulatory 
Commission, Washington, DC 20555-0001, Attention: Rulemakings and 
Adjudications Staff.

[[Page 34600]]

    Deliver comments to: 11555 Rockville Pike, Rockville, Maryland, 
between 7:30 a.m. and 4:15 p.m. on Federal workdays.
    For a copy of the petition, write to David L. Meyer, Chief, Rules 
and Directives Branch, Division of Administrative Services, Office of 
Administration, U.S. Nuclear Regulatory Commission, Washington, DC 
20555-0001.
    The petition, this notice of receipt, and any comments received on 
the petition are available on the NRC's rulemaking website at http://ruleforum.llnl.gov. This site also provides the capability to upload 
comments as files (any format), if your web browser supports that 
function. For information about the interactive rulemaking website, 
contact Ms. Carol Gallagher, (301) 415-5905 (e-mail:[email protected]).

FOR FURTHER INFORMATION CONTACT: David L. Meyer, Chief, Rules and 
Directives Branch, Division of Administrative Services, Office of 
Administration, U.S. Nuclear Regulatory Commission, Washington, DC 
20555-0001, Telephone: 301-415-7162 or Toll Free: 1-800-368-5642 or 
email: [email protected].

SUPPLEMENTARY INFORMATION:

The Petitioner

    The petitioner is the Nuclear Energy Institute (NEI). NEI claims 
representational responsibility for establishing unified nuclear 
industry policy on matters affecting the nuclear energy industry, 
including regulatory aspects of generic operational and technical 
issues. NEI's members include all utilities licensed to operate 
commercial nuclear power plants in the United States, nuclear plant 
designers, major architect/engineering firms, fuel fabrication 
facilities, materials licensees, and other organizations and 
individuals involved in the nuclear energy industry.

The Petitioner's Request

    The petitioner states that the NRC's current regulations require 
uranium oxide fuel pellets, used in commercial reactors, be contained 
in cladding material made of zircaloy or ZIRLO. The petitioner 
indicates that the requirement to use either of these materials is 
stated in 10 CFR 50.44 and 10 CFR 50.46.
    The petitioner notes that subsequent to promulgation of these 
regulations, commercial fuel vendors have developed and continue to 
develop materials other than zircaloy or ZIRLO that NRC reviews and 
approves for use in commercial power reactors. Each of these approvals 
requires the NRC to grant an exemption to the license of the utility 
that requests use of fuel in these cladding materials. The petitioner 
requests that NRC amend its regulations to allow licensees discretion 
to use zirconium-based cladding materials other than zircaloy or ZIRLO, 
provided that the cladding materials meet the fuel cladding performance 
requirements and have been reviewed and approved by NRC staff.

Petitioner's Interest

    The petitioner states that safe and reliable operation of nuclear 
power plants, including fuel performance is very important to its 
members, the country, and the international community. The petitioner 
states that the NRC regulates the use of radioactive materials and 
allows nuclear power plant licensees to use a variety of cladding 
materials once the material has been determined to have the required 
characteristics. The petitioner states that for the past nine years, 
NRC has permitted the use of cladding materials other than zircaloy or 
ZIRLO after approving a formal exemption request. The petitioner 
further notes there have been at least eight requests for exemptions 
during that time frame and each exemption costs in excess of $50,000. 
The petitioner states that the requests for exemption have become 
increasingly more frequent, causing significant administrative 
confusion and a potentially adverse affect on efficient and effective 
use of NRC, licensee, and vendor resources.

Justification for Petition

    Sections A through D below contain the detailed discussion provided 
by the petitioner to support his request. The text contained in each of 
these sections reflects the petitioner's point of view word for word.

A. The Current Regulation Given the Diversity of Commercially Available 
Fuel Cladding Materials is too Narrow and Restrictive

    The beneficial use of zirconium (Zr) has been recognized for many 
years. It has a very low neutron cross-section when separated from 
hafnium with which it is typically found in nature. It also has 
excellent corrosion resistance to oxidizing environments, such as steam 
and water. Certain impurities were found to decrease this corrosion 
resistance and early programs were established to develop alloys that 
produced more consistent corrosion resistance.
    Primary additives were tin, as used initially in a variety of 
zirconium-based alloys commonly referred to as zircaloy, and niobium 
(Nb) favored in Canada and Russia.
    Beginning in approximately the mid-1980's, nuclear fuel vendors 
began developing new alloy variations to improve cladding corrosion 
resistance in support of higher burnup fuel management strategies. The 
new alloy variants were initially within the ASTM [American Society for 
Testing and Materials] specifications for existing zirconium-based 
cladding. As fuel cycle burnups were projected to increase further, 
additional alloys were developed, some of which involved formulations 
outside the ASTM specifications for existing cladding material.
    The tin (Sn) additive-based alloys were generally favored in the 
U.S. and were successfully developed in both BWR [boiling water 
reactor] and PWR [pressurized water reactor] reactors. Early Zr-Sn 
alloys tended to use relatively high tin concentrations until long term 
corrosion tests showed that there was an increase in the corrosion rate 
as a function of time. Subsequent developments of the alloy, currently 
defined as Zircaloy-2 and Zircaloy-4, limited tin concentration to 
between 1.2 percent and 1.7 percent. Most of the early zircaloy 
compositions were at a nominal 1.5 percent Sn. Subsequent testing of 
the alloy in high rated PWR plants has shown that the lower tin 
concentrations provide even better performance. Current zircaloy 
compositions tend to focus on a mean Sn composition of about 1.3 
percent. That value has been established by producers to minimize the 
risk of manufacturing a product below the ASTM specified range. 
However, there is significant data to show that lower Sn compositions 
would provide even better corrosion resistance.
    Excellent corrosion performance has also been achieved with the 
niobium additive-based alloys; however, these appear to be more 
sensitive to the coolant composition. For example, the corrosion 
resistance is superior to the tin additive-based alloy under PWR 
environments but tends to suffer from nodular-type oxidation under BWR 
conditions. The alloy is much less temperature sensitive and the oxide 
thickness is generally less than that of the corresponding corrosion 
layer on zircaloy irradiated under identical conditions. The optimum 
niobium content is probably about one percent, or such as is found in 
M5 or ZIRLO cladding alloys.
    The major variant on the Zr-Sn and Zr-Nb systems is the Zr-Sn-Nb 
system developed in the US as ZIRLO and in Russia as E635.

[[Page 34601]]

    As a result of these development programs, cladding materials now 
available include zircaloy, ZIRLO, Alloy A, M5, and Duplex. All of 
these alloys are zirconium-based. Since zircaloy and ZIRLO are 
currently the only cladding materials provided for in the regulations, 
utilities must obtain an exemption from the applicable regulatory 
requirements to use these other cladding materials. Exemption requests 
will become more frequent as use of new cladding materials becomes more 
prevalent. Once a specific cladding material is approved for use by 
NRC, the subsequent exemption requests do not increase safety or 
confidence in the performance of the cladding. They are strictly an 
administrative process necessitated by the restrictive language of the 
current regulations.
    The rule should be modified to address the currently available 
alloys as well as those that may be developed in the future.

B. A More General Description of Cladding Material Facilitates 
Technical Improvements

    Currently, a licensee desiring to use fuel with cladding materials 
other than zircaloy or ZIRLO must obtain NRC approval through an 
exemption request. The time delay in obtaining approval as well as 
expenses incurred in preparing exemption requests might cause some 
licensees to defer adopting new cladding materials despite performance 
advantages to be gained. The proposed amendments would permit use of 
improved cladding materials without expending NRC, licensee, and vendor 
resources to develop, review, and approve exemption requests for 
cladding materials that fully meet NRC performance requirements.
    Since the current industry interest focuses on cladding materials 
for which the performance criteria in Sec. 50.46(b) remain applicable, 
a new Sec. 50.46(e) is proposed that provides a clear tie between the 
approved cladding material alloy mentioned in Secs. 50.44 and 50.46 
with the criteria noted in Sec. 50.46(b).
    Similarly, to facilitate technical innovation, the NRC staff often 
encourages licensees and vendors to conduct Lead Test Assembly (LTA) 
Programs to demonstrate the performance of the new fuel assembly 
materials. It has been the past practice of the NRC not to require 
licensees to obtain approval of the LTA Program before placing the LTAs 
in the reactor. It is not the intent of industry to change that 
practice by making reference to approved cylindrical zirconium-based 
alloys in Secs. 50.44 and 50.46.

C. The Regulation as Applied to Nuclear Power Plant Fuel Loading Incurs 
Unwarranted Implementation Costs

    The implication of the current rule language that only the use of 
zircaloy or ZIRLO clad fuel is appropriate requires utilities to 
request, and NRC to approve, exemptions to use other cladding 
materials. Each exemption request is estimated to cost approximately 
$50,000, exclusive of NRC's cost. It is also estimated that the 
proposed change to the regulations could avoid at least thirty 
exemption requests over the next 8 to 9 years.

D. The Proposed Amendment Allows the Use of Alternative Materials That 
Meet the Cladding Performance Requirements

    The existing regulations address only zircaloy and ZIRLO cladding 
materials. The regulation needs to be generalized to avoid unnecessary 
burdens on the developers of new cladding alloys and utilities who will 
use those alloys. The language of this proposed amendment will 
encompass all zirconium-based cladding material for which the ECCS 
performance criteria of Sec. 50.46(b) are applicable.
    The proposed wording does not eliminate current NRC practices 
regarding review and approval of new cladding materials brought forward 
by fuel vendors. It does permit the NRC regulation to be more 
efficiently applied to those cladding materials demonstrated to meet 
the acceptance criteria of Secs. 50.46(b)(1) and (b)(2).
    Experience has shown that qualification of an acceptable material 
can only be achieved by testing. An applicant must perform high-
temperature oxidation and quenching tests of the cladding material to 
demonstrate that the 2200-degrees F peak cladding temperature and 17 
percent oxidation limits protect the cladding against embrittlement and 
prevent the oxidation from becoming autocatalytic. This is demonstrated 
by heating the cladding to various high temperatures for a variety of 
time periods and quickly quenching the cladding in a cold water bath.
    These tests must demonstrate that failure did not occur until 
beyond the temperature limits and that no autocatalytic oxidation was 
observed. As long as the tests confirm that the 2200-degrees F and 17 
percent oxidation are conservative for the cladding material, then the 
material design is acceptable for LOCA [loss-of-coolant accident] 
licensing analyses up to currently approved burn up limits.
    Providing a new more general description of the fuel cladding is 
consistent with the NRC movement toward a performance-based, rather 
than prescriptive, regulatory philosophy.

Conclusion

    The petitioner believes the foregoing reasons support why NRC 
should amend Secs. 50.44 and 50.46, as stated above, to allow the use 
of other zirconium-based alloys in addition to those specified in the 
current regulation.
    The petitioner recognizes that the stated goal of the existing 
regulations is to ensure adequate coolability for reactor fuel in case 
of a design-basis accident. However, the petitioner asserts that the 
proposed amendment does not degrade the ability to meet that goal. 
Rather, it removes an unwarranted licensing burden without increasing 
risk to public health and safety.

Proposed Amendments

    According to the petitioner, the proposed amendments would continue 
to allow nuclear power plant licensees the discretion to use zircaloy 
or ZIRLO cladding to encase the uranium dioxide fuel pellets. The 
proposed amendments also would allow nuclear power plant licensees to 
use other cladding materials with material properties that meet 
accepted requirements for fuel cladding performance. The petitioner 
identifies the proposed amendments as follows:

PART 50--[AMENDED]

    1. Section 50.44, paragraphs (a), (b), and (c)(1) are revised to 
read as follows:


Sec. 50.44  Standards for combustible gas control system in light-
water-cooled nuclear power reactors.

    (a) Each boiling or pressurized light-water nuclear power reactor 
fueled with oxide pellets within approved cylindrical zirconium-based 
alloy cladding, must . . .
    (b) Each boiling or pressurized light-water nuclear power reactor 
fueled with oxide pellets within approved cylindrical zirconium-based 
alloy cladding must . . .
    (c)(1) For each boiling or pressurized light-water nuclear power 
reactor fueled with oxide pellets within approved cylindrical 
zirconium-based alloy cladding, it must be shown that . . .
    2. Section 50.46(a)(1)(i) is revised to read as follows:


Sec. 50.46  Acceptance criteria for emergency core cooling systems for 
light-water nuclear power reactors.

    (a)(1)(i) Each boiling or pressurized light-water nuclear power 
reactor fueled with uranium oxide pellets within approved cylindrical 
zirconium-based alloy cladding must be provided with an

[[Page 34602]]

emergency core cooling system (ECCS) that must be designed so that its 
calculated cooling performance following postulated loss-of-coolant 
accidents conforms to the criteria set forth in paragraph (b) of this 
section. . . .
    3. In Section 50.46, a new paragraph (e) is added to read as 
follows:
    (e) Approved cylindrical zirconium-based alloys are those whose 
performance has been evaluated and determined by the NRC to conform to 
the acceptance criteria of paragraphs Sec. 50.46(b)(1) and (b)(2).

    Dated at Rockville, Maryland this 24th day of May, 2000.

    For the Nuclear Regulatory Commission.
Annette L. Vietti-Cook,
Secretary of the Commission.
[FR Doc. 00-13515 Filed 5-30-00; 8:45 am]
BILLING CODE 7590-01-P