02-16719. Maine Yankee Atomic Power Company; Independent Spent Fuel Storage Installation, Issuance of Environmental Assessment and Finding of No Significant Impact for the Proposed Exemption From Certain Requirements of 10 CFR Part 72

The U.S. Nuclear Regulatory Commission (NRC or Commission) is considering issuance of an exemption to Maine Yankee Atomic Power Company (MYAPC or licensee), pursuant to 10 CFR 72.7, from specific provisions of 10 CFR 72.212(a)(2), 72.212(b)(2)(i), 72.212(b)(7), and 72.214. The licensee is planning to use the NAC-UMS Storage System to store spent nuclear fuel from the decommissioning reactor. The requested exemption would allow MYAPC to deviate from requirements of the NAC-UMS Certificate of Compliance No. 1015 (CoC or Certificate), Appendix A, Limiting Condition for Operation (LCO) Items 3.2.1.a and 3.2.1.b, “CANISTER Surface Contamination.” Specifically, the requested exemption would allow an increase in removable contamination limits on the accessible NAC-UMS exterior canister surfaces and interior transfer cask surfaces from 1000 dpm/100 cm² for beta-gamma sources and 20 dpm/100 cm² for alpha sources, which is required by the Certificate, to 10,000 dpm/100 cm² for beta-gamma sources and 100 dpm/100 cm² for alpha sources. The potential increase in radiation dose to members of the public from this exemption request was determined to be up to 1.42 mrem/year at 100 meters. Even with this potential increase in dose, the overall potential dose to members of the public would remain within the requirements of 10 CFR 72.104, 10 CFR 72.106 and 10 CFR 20.1301.

Environmental Assessment (EA)

Identification of Proposed Action: By letter dated October 30, 2001, as supplemented on November 29, 2001, and February 7, 2002, MYAPC requested an exemption from the requirements of 10 CFR 72.212(a)(2), 72.212(b)(2)(i), 72.212(b)(7), and 72.214 to deviate from the requirements in CoC No. 1015, Appendix A, LCO Items 3.2.1.a and 3.2.1.b. MYAPC has informed the NRC of its plans to store spent nuclear fuel under the general licensing provisions of 10 CFR Part 72. The licensee indicated that it plans to use the NAC-UMS Storage System to store spent fuel from the Maine Yankee Atomic Power Station at an Independent Spent Fuel Storage Installation (ISFSI) located in Wiscasset, Maine.

By exempting MYAPC from 10 CFR 72.212(a)(2), 72.212(b)(2)(i), 72.212(b)(7), and 72.214, MYAPC will be authorized to increase the removable contamination limits on the accessible exterior canister surfaces and interior transfer cask surfaces. The contamination limits required by CoC No. 1015 are 1000 dpm/100 cm² for beta-gamma source and 20 dpm/100 cm² for alpha sources. Instead, MYAPC requested to limit removable contamination on the accessible exterior canister surface and interior transfer cask surface to 10,000 dpm/100 cm² for beta-gamma sources and 100 dpm/100 cm² for alpha sources.

The proposed action before the Commission is whether to grant this exemption under 10 CFR 72.7.The NRC staff has reviewed the exemption request and determined that the revised LCO contamination limits are consistent with the safety analyses previously reviewed for the NAC-UMS system, and would have no impact on the design basis and would not be inimical to public health and safety.

Need for the Proposed Action: The MYAPC fuel loading campaign is scheduled to begin in July 2002. An avoidance of potential excessive radiological exposure to workers during this campaign could be achieved if the storage canisters were allowed to be stored with higher surface contamination. The licensee calculated that a reduction in radiological exposure to the operators, fuel handlers, and security personnel involved in handling, preparing and transferring the canisters could be over 5 rem during the dry spent fuel loading campaign with the revised contamination limits in the exemption request.

Environmental Impacts of the Proposed Action: MYAPC requested the exemption to increase storage canister contamination limits. The staff performed a safety evaluation of the proposed exemption. The analysis in the NAC-UMS Safety Analysis Report (SAR) for radioactive particulate release was previously reviewed by NRC staff. The analysis demonstrated that residual contamination levels of approximately 157,000 dpm/100 cm² from beta-gamma sources, and 524 dpm/100 cm² from alpha sources yields a dose from direct exposure of 2 mrem at a distance of 100 meters for an array of 20 canisters. MYAPC's proposed LCO contamination limits are 10,000 dpm/100 cm² for beta-gamma sources, and 100 dpm/100 cm² for alpha sources. These proposed new limits remain significantly less than those assumed in the currently approved NAC-UMS SAR. The safety evaluation performed by the staff concludes that the NRC has reasonable assurance that increasing the removal surface contamination limits to 10,000 dpm/100 cm² beta-gamma and 100 dpm/100 cm² alpha has minimal impact on off-site doses, results in a dose savings to workers, and meets the requirements of 10 CFR 72.104, 10 CFR 72.106 and 10 CFR 20.1301, and is therefore acceptable.

MYAPC submitted two independent calculations to support the exemption request. In the first case, MYAPC assumed that a contamination release fraction of 5% of the removable surface contamination from 20 canisters is instantaneously released through the storage overpack vents to the environment. The analysis showed that the off-site impact from the event is 0.72 mrem/year at 100 meters. In the second analysis, MYAPC conservatively assumed that the entire isotopic inventory of the cask surface was released at 100 meters away, ignoring the wake effects of the berm surround the cask storage pad. These assumptions lead to a calculated does of 1.42 mrem/year at 100 meters. The staff reviewed the assumptions and calculation and agrees that the analyses are conservative. Therefore, the environmental impact of increasing the LCO contamination limits is no greater than the environmental impact already assessed in the initial rulemaking for the NAC-UMS Storage System (65 FR 62581, dated October 19, 2001).

The proposed action will not significantly increase the probability or consequences of the analyzed accidents, no changes are being made to the types of effluents that may be released offsite, and there is no significant increase in occupational or public radiation exposure. Therefore, there are no significant radiological environmental impacts associated with the proposed action. Therefore, the staff has determined that there is no reduction in the ability of the system to perform its safety function, nor significant environmental impacts, as a result of increasing the contamination limits in LCO 3.2.1.a and 3.2.1.b.

Alternative to the Proposed Action: Since there is no significant environment impact associated with the proposed action, alternatives with equal or greater environmental impact are not evaluated. The alternative to the proposed action would be to deny approval of the exemption. Denial of the exemption request will have the same environmental impact, but would result in a potential dose increase to workers involved in cask decontamination activities.

Agencies and Persons Consulted: On March 14, 2002, Mr. Patrick J. Dostie of the Office of Nuclear Safety Division of Health Engineering for the State of Maine submitted comments to the NRC on the MYAPC exemption request. The potential safety issues raised by Mr. Dostie were considered by NRC staff in the evaluation of the exemption request and did not provide sufficient basis to deny the exemption request. The Commission addressed Mr. Dostie's comments in a letter dated June 21, 2002.

Finding of No Significant Impact

The environmental impacts of the proposed action have been reviewed in accordance with the requirements set forth in 10 CFR Part 51. Based upon the foregoing EA, the Commission finds that the proposed action of granting the exemption from 10 CFR 72.212(a)(2), 72.212(b)(2)(i), 72.212(b)(7), and 72.214 allowing MYAPC to increase contamination limits for the accessible exterior surfaces of the storage canisters and accessible interior surfaces of the transfer cask from 1000 dpm/100 cm² for beta-gamma sources to 10,000 dpm/100 cm² and from 20 dpm/100 cm² for alpha sources to 100 dpm/100 cm² will not significantly impact the quality of the human environment. Accordingly, the Commission has determined that an environmental impact statement for the proposed exemption is not warranted.

The request for exemption was docketed under 10 CFR Part 72, Docket 72-30. For further details with respect to this action, see the exemption request dated October 30, 2001, as supplemented November 29, 2001, and February 7, 2002. The NRC maintains an Agencywide Documents Access and Management System (ADAMS), which provides text and image files of NRC's public documents. These documents may be accessed through the NRC's Public Electronic Reading Room on the Internet at http://www.nrc.gov/​NRC/​ADAMS/​index.html. If you do not have access to ADAMS or if there are problems in accessing the documents located in ADAMS, contact the NRC Public Document Room (PDR) Reference staff at 1-800-397-4209, 301-415-4737, or by e-mail to [e-mail].

Dated at Rockville, Maryland, this 25th day of June 2002.

For the Nuclear Regulatory Commission.

E. William Brach,

Director, Spent Fuel Project Office, Office of Nuclear Material Safety and Safeguards.