05-5679. Entergy Nuclear Vermont Yankee, LLC and Entergy Nuclear Operations, Inc. Vermont Yankee Nuclear Power Station; Exemption

1.0 Background

Entergy Nuclear Vermont Yankee, LLC and Entergy Nuclear Operations, Inc. (Entergy or the licensee) are the holders of Facility Operating License No. DPR-28 which authorizes operation of the Vermont Yankee Nuclear Power Station (VYNPS). 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 Vernon, Vermont.

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 which penetrate the containment. Option B of Appendix J is titled “Performance-Based Requirements.” Option B, section III.A., “Type A Test,” requires 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, as specified in the 10 CFR part 50, Appendix J, Option B, definitions, means the total leakage rate through all tested leakage paths. The licensee is requesting a permanent exemption from Option B, section III.A., requirements to permit exclusion of the main steam pathway leakage contributions from the overall integrated leakage rate Type A 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 that the sum of the leakage rates of all Type B and Type C local leak rate 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 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 main steam pathways). The proposed exemption would more appropriately permit ALT pathway leakage to be independently grouped with its unique leakage limits. In this manner, the VYNPS containment leakage testing program will be made more consistent with the limiting assumptions used in the associated accident consequence analyses.

The licensee has analyzed the main steam leakage pathway (with an increase in leakage from 62 standard cubic feet per hour (scfh) to 124 scfh at the calculated peak containment internal pressure (Pa)), the secondary containment bypass leakage pathways, and the containment leakage pathway (La) separately in their dose consequence analyses. The calculated radiological consequences of the combined leakages are within the criteria of 10 CFR 50.67. The NRC staff reviewed the licensee's analyses and found them 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 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 part 50.12(a)(2)(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. * * *”

The licensee's exemption request was submitted in conjunction with a TS amendment application to increase the allowable leak rate for the main steam isolation valves (MSIVs). The proposed amendment will be issued concurrently with this exemption. The exemption and amendments 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. The NRC staff has determined that the intent of the rule is not compromised by the proposed action.

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 part 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 Entergy an exemption from the requirements of sections III.A and III.B of Option B of Appendix J to 10 CFR part 50 for VYNPS.

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 (69 FR 67612).

This exemption is effective upon issuance.

Dated at Rockville, Maryland, this 17th day of March 2005.

For the Nuclear Regulatory Commission.

Ledyard B. Marsh,

Director, Division of Licensing Project Management, Office of Nuclear Reactor Regulation.