[Federal Register Volume 71, Number 215 (Tuesday, November 7, 2006)]
[Notices]
[Pages 65137-65138]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E6-18711]
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NUCLEAR REGULATORY COMMISSION
[Docket No. 50-298]
Nebraska Public Power District, Cooper Nuclear Station; Exemption
1.0 Background
Nebraska Public Power District (NPPD or the licensee) are the
holders 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 all 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), section
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. Option B of Appendix J is titled, ``Performance-Based
Requirements.'' Option B, 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 leak 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 from MSIV leakage. The licensee has requested
exemption from Option B, Section III.A requirements to permit exclusion
of MSIV leakage from the overall integrated leak rate test measurement.
Main steam leakage includes leakage through all four main steam lines
and the main steam 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. The licensee also requests exemption
from this requirement, to permit exclusion of the main steam pathway
leakage contributions from the sum of the leakage rates from Type B and
Type C tests.
The main steam 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 main steam isolation valve (MSIV) leakage is directed through the
main steam drain piping into the condenser and is released into the
environment as an unfiltered ground level effluent.
In summary, the licensee analyzed the MSIV leakage pathway and the
containment leakage pathways separately in a dose consequences
analysis. The calculated radiological consequences of the combined
leakage were found to be within the criteria of 10 CFR part 100 and
General Design Criterion (GDC) 19. The NRC staff reviewed the
licensee's analyses and found them acceptable as described in a safety
evaluation dated September 1, 2004. By separating the MSIV leakage
acceptance criteria from the overall integrated leak rate test
criterion, and from the Type B and C leakage sum limitation, the CNS
containment leakage testing will be made more consistent with the
limiting assumptions used in the associated accident consequences
analyses.
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 and
safety, and are consistent with the common defense and security, and
(2) when special circumstances are present. Special circumstances are
present whenever, according to 10 CFR 50.12(a)(2):
(i) Application of the regulation in the particular circumstances
conflicts with other rules or requirements of the Commission; or
(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; or
(iii) Compliance would result in undue hardship or other costs that
are significantly in excess of those contemplated when the regulation
was adopted, or that are significantly in excess of those incurred by
others similarly situated; or
[[Page 65138]]
(iv) The exemption would result in benefit to the public health and
safety that compensates for any decrease in safety that may result from
the grant of the exemption; or
(v) The exemption would provide only temporary relief from the
applicable regulation and the licensee or applicant has made good faith
efforts to comply with the regulation; or
(vi) There is present any other material circumstance not
considered when the regulation was adopted for which it would be in the
public interest to grant an exemption. If such condition is relied on
exclusively for satisfying paragraph (a)(2) of this section, the
exemption may not be granted until the Executive Director for
Operations has consulted with the Commission.
The licensee's exemption request was submitted in conjunction with
a TS amendment application to increase the allowable leak rate for the
MSIVs. The proposed amendment will be issued concurrently with this
exemption. The exemption and amendment together would implement the
recommendations of Topical Report NEDC-31858, ``BWR Report for
Increasing MSIV Leakage Rate Limits and Elimination of Leakage Control
Systems.'' The topical report was evaluated by the NRC staff and
accepted in a safety evaluation dated March 3, 1999. The special
circumstances associated with MSIV leakage testing are fully described
in the topical report. These circumstances relate to the monetary costs
and personnel radiation exposure involved with maintaining MSIV leakage
limits more restrictive than necessary to meet offsite dose criteria
and control room habitability criteria.
The underlying purpose of the rule which implements Appendix J
(i.e., 10 CFR 50.54(o)) is to assure 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 the
exemption, thus, the probability of postulated accidents is not
increased. Also, based on the above, the consequences of postulated
accidents are not increased. As such, the NRC staff has determined that
the intent of the rule is not compromised by the proposed exemption.
The proposed exemption would permit exclusion of the main steam
pathway leakage contributions from the overall integrated leakage rate
Type A test measurement. This change has no relation to security
issues. Therefore, the common defense and security is not impacted by
this exemption.
Based on the foregoing, the separation of the main steam pathways
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 be acceptable.
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 from the
requirements of Sections III.A and III.B of Option B of Appendix J to
10 CFR part 50 for CNS.
Pursuant to 10 CFR 51.32, the Commission has determined that the
granting of this exemption will have no significant impact on the
quality of the human environment (71 FR 61074).
This exemption is effective upon issuance.
Dated at Rockville, Maryland, this 30th day of October 2006.
For the Nuclear Regulatory Commission.
Catherine Haney,
Director, Division of Operating Reactor Licensing, Office of Nuclear
Reactor Regulation.
[FR Doc. E6-18711 Filed 11-6-06; 8:45 am]
BILLING CODE 7590-01-P