[Federal Register Volume 74, Number 181 (Monday, September 21, 2009)]
[Notices]
[Pages 48103-48104]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E9-22600]
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NUCLEAR REGULATORY COMMISSION
[Docket No. 50-298; NRC-2009-0398]
Nebraska Public Power District; Cooper Nuclear Station; Exemption
1.0 Background
Nebraska Public Power District (NPPD or the licensee) is the holder
of Facility Operating License No. DPR-46 which authorizes operation of
the Cooper Nuclear Station (CNS). The license provides, among other
things, that the facility is subject to the rules, regulations, and
orders of the Nuclear Regulatory Commission (NRC, the Commission) now
or hereafter in effect.
The facility consists of a boiling-water reactor located in Nemaha
County, Nebraska.
2.0 Request/Action
Title 10 of the Code of Federal Regulations (10 CFR), Part 50,
paragraph 50.54(o), requires primary reactor containments for water-
cooled power reactors to be subject to the requirements of Appendix J
to 10 CFR Part 50. Appendix J specifies the leakage test requirements,
schedules, and acceptance criteria for tests of the leak-tight
integrity of the primary reactor containment and systems and components
that penetrate the containment. Appendix J, Option B, ``Performance-
Based Requirements,'' Section III.A., ``Type A Test,'' requires, among
other things, that the overall integrated leakage rate must not exceed
the allowable leakage rate (La) with margin, as specified in the
Technical Specifications (TSs). The overall integrated leakage rate is
defined in 10 CFR Part 50, Appendix J as ``the total leakage rate
through all tested leakage paths, including containment welds, valves,
fittings, and components that penetrate the containment system.'' This
includes the contribution through the four main steam (MS) lines and
the MS inboard drain line (penetration X-8). The MS Pathway includes
leakage from the MS line penetrations plus the MS inboard drain line.
Option B, Section III.B of 10 CFR Part 50, Appendix J, ``Type B and
C Tests,'' requires, among other things, that the sum of the leakage
rates at accident pressure of Type B tests and pathway leakage rates
from Type C tests be less than the performance criterion (La) with
margin, as specified in the TSs.
By application dated October 13, 2008, as supplemented by letters
dated April 8, May 29, June 12, and September 1, 2009, the licensee
requested exemption from Option B, Section III.A requirements in order
to permit exclusion of MS Pathway leakage from the overall integrated
leak rate test measurement. The licensee also requested exemption from
Option B, Section III.B requirements in order to permit exclusion of
the MS Pathway leakage contributions from the sum of the leakage rates
from Type B and Type C tests. The licensee's application included a
license amendment request to revise the radiological assessment
calculation methodology for the design basis loss-of-coolant accident
at CNS through application of the alternative source term, in
accordance with the provisions of 10 CFR 50.67 and 50.90, and to revise
the TSs accordingly.
The NRC previously granted a license amendment (Amendment No. 226,
dated October 31, 2006) and an exemption (letter to licensee dated
October 30, 2006) from (1) Option B, Section III.A requirements in
order to permit exclusion of MS isolation valve (MSIV) leakage from the
overall integrated leakage rate measured when performing a Type A test,
and (2) Option B, Section III.B requirements in order to permit
exclusion of the MSIV leakage from the combined leakage rate of the
penetrations and valves subject to Type B and Type C tests. The only
difference in the current exemption request is the inclusion of the
leakage contribution from the MS inboard drain line with the MSIV
leakage in the MS Pathway.
The MS leakage effluent has a different pathway to the environment,
when compared to a typical containment penetration. It is not directed
into the secondary containment and filtered through the standby gas
treatment system as is other containment leakage. Instead, the MS
leakage is collected and treated via an alternative leakage treatment
(ALT) path having different mitigation characteristics.
In performing accident analyses, it is appropriate to group various
leakage effluents according to the treatment they receive before being
released to the environment (e.g., from MS pathways). The proposed
exemption would more appropriately permit ALT pathway leakage to be
independently grouped with its unique leakage limits. In this manner,
the CNS containment leakage testing program will be more consistent
with the limiting assumptions used in the associated accident
consequence analyses.
The licensee has analyzed the MS Pathway leakage separately from
the overall containment integrated leakage, local leakage across
pressure retaining, leakage limiting boundaries, and containment
isolation valve leakage in its dose consequence analyses. Specifically,
the alternative source term design-basis accident analyses use the MS
piping, MS drain lines, and main condenser as an alternate means for MS
Pathway leakage treatment. The dose consequences were found to be
within the acceptance criteria of 10 CFR 50.67, ``Accident source
term,'' and the guidance of NRC Regulatory Guide
[[Page 48104]]
1.183, ``Alternative Radiological Source Terms for Evaluating Design
Basis Accidents at Nuclear Power Reactors,'' dated July 2000.
Therefore, the separation of the MS Pathway from the other
containment leakage pathways is warranted because a separate
radiological consequence term has been provided for these pathways. The
revised design-basis radiological consequences analyses address these
pathways as individual factors, exclusive of the primary containment
leakage. Therefore, the NRC staff finds the proposed exemption from
Appendix J, to separate MS leakage from other containment leakage, to
be acceptable.
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. The licensee's exemption
request was submitted with a license amendment request to use the
alternative source term methodology for use in calculating the dose
consequences of the design-basis loss-of-coolant accident analysis. The
NRC staff will issue the proposed amendment in conjunction with the
exemption. The exemption and amendment together would implement the
alternative source term methodology. The special circumstances
associated with the MS Pathway leakage testing are fully described in
the licensee's application dated October 13, 2008, as supplemented by
letters dated April 8, May 29, June 12, and September 1, 2009, and
discussed below.
Authorized by Law
This exemption would permit exclusion of the MS Pathway leakage
contribution from the overall integrated leakage rate Type A test
measurement and from the sum of the leakage rates from Type B and Type
C tests. 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
The underlying purposes of 10 CFR Part 50, Appendix J, Option B,
Sections III.A and III.B are to ensure that containment leak-tight
integrity is maintained (a) as tight as reasonably achievable and (b)
sufficiently tight so as to limit effluent release to values bounded by
the analyses of radiological consequences of design-basis accidents.
Based on the above, no new accident precursors are created by exclusion
of the MS Pathway leakage contribution from the overall integrated
leakage rate Type A test measurement and from the sum of the leakage
rates from Type B and Type C tests, thus, the probability of postulated
accidents is not increased. Also, based on the above, the consequences
of postulated accidents are not increased. Therefore, there is no undue
risk to public health and safety.
Consistent With Common Defense and Security
The proposed exemption would exclude the MS Pathway leakage
contribution from the overall integrated leakage rate Type A test
measurement and from the sum of the leakage rates from Type B and Type
C tests. This change to the operation of the plant has no relation to
security issues. Therefore, the common defense and security is not
impacted by this exemption.
Special Circumstances
Special circumstances include, in part, the special circumstances
defined in 10 CFR 50.12(a)(2)(ii), which states, ``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.''
The underlying purpose of 10 CFR Part 50, Appendix J, is to ensure
that containment leak-tight integrity is maintained as tight as
reasonably achievable and sufficiently tight so as to limit effluent
release to values bounded by the analyses of radiological consequences
of design-basis accidents. The intent of the rule is not compromised by
the licensee's proposed action because the containment leak rates will
continue to be limited by CNS's TSs. The proposed action will
appropriately permit ALT pathway leakage to be independently grouped
with its unique leakage limits and maintain the accident dose analyses
consequences within the acceptance criteria of 10 CFR 50.67.
Therefore, since the underlying purposes of 10 CFR Part 50,
Appendix J, is achieved, the special circumstances required by 10 CFR
50.12(a)(2)(ii) for the granting of an exemption from 10 CFR Part 50,
Appendix J, Option B, Sections III.A and III.B exist.
4.0 Conclusion
Accordingly, the Commission has determined that, pursuant to 10 CFR
50.12, 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 NPPD an exemption (1) from the
requirements of 10 CFR Part 50, Appendix J, Option B, Section III.A, to
allow exclusion of the MS Pathway leakage from the overall integrated
leakage rate measured when performing a Type A test; and (2) from the
requirements of 10 CFR Part 50, Appendix J, Option B, Section III.B, to
allow exclusion of the MS Pathway leakage from the combined leakage
rate of all penetrations and valves subject to Type B and C tests for
CNS.
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 (74 FR 47030; September 14, 2009).
This exemption is effective upon issuance.
Dated at Rockville, Maryland, this 14th day of September 2009.
For the Nuclear Regulatory Commission.
Joseph G. Giitter,
Director, Division of Operating Reactor Licensing, Office of Nuclear
Reactor Regulation.
[FR Doc. E9-22600 Filed 9-18-09; 8:45 am]
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