Aircraft impact assessments might be required for all new plants

In a major change from its earlier proposal, the NRC staff is recommending in a final rule that is making its way to the commission that all new plant license applicants would be required to perform an aircraft impact assessment before a reactor is built.

The proposed rule, published last October, had restricted the applicability to future design certifications, combined construction permit-operating licenses, or COLs, that did not reference a certified design, and new manufacturing licenses. It had suggested that previously certified designs, which would include GE-Hitachi's ABWR, Westinghouse's (formerly Combustion Engineering) System 80+, and Westinghouse's AP600 and AP1000, be exempt from such a security assessment. The exemption was widely opposed in comments sent to the agency by members of the public, citizen groups and even some companies pursuing licenses to build new reactors.

In the final proposed rule, the staff said it had revised its approach to include virtually all new plant applicants -- regardless of whether an existing certified standard design was referenced. The staff previewed some of the rule changes in a briefing to the NRC's Advisory Committee on Reactor Safeguards on July 9.

The staff said the proposed final rule is expected to be sent to the NRC's executive director for operations in mid-September and forwarded to the commission by September 30.

"The rule's applicability would now extend to COL applicants or construction permit [applicants]," said William Reckley, chief of NRC's rulemaking, guidance and advanced reactors project branch. Under the changes, he said, the only exception would be Tennessee Valley Authority's Watts Bar-2, which already has a construction permit. TVA is in the process of completing the partially built unit under NRC's traditional, two-part licensing process, 10 CFR Part 50, and anticipates putting the reactor in commercial operation in 2012.

Initially, the staff proposed a new requirement under 10 CFR Part 52, which governs early site permits, standard design certifications and COLs, for applicants to assess a large commercial aircraft crash at a new reactor and incorporate into the plant design features that would mitigate or minimize the effects of the impact and reduce or eliminate the need for operator actions.

In the final proposed rule, the staff moved the requirement into Part 50.

Reckley said there were two reasons for moving the requirement. "One is it will apply to future construction permits issued under Part 50. The second is, as a general philosophy, Part 52 is a process rule that points to other places -- Part 50, Part 20, Part 100 -- for the technical requirements." He said it was more consistent to have the aircraft crash impact assessment, which is considered to be a technical requirement, under Part 50.

He said there would be a "pointer" in the Part 52 requirements to the aircraft assessment requirement in Part 50.

The staff's presentation to the ACRS said the final rule language would, if approved by the commission, require new plant applicants to incorporate "design features and functional capabilities that avoid or mitigate, to the extent practical and with reduced reliance on operator actions, the effects of the aircraft impact on core cooling capability, containment integrity, spent fuel cooling capability, and spent fuel pool integrity."

The Nuclear Energy Institute had urged the agency to require new plant applicants to demonstrate that either spent fuel cooling or spent fuel integrity is maintained -- but not both. It had argued that demonstrating both was unnecessary because it is possible to cool the fuel even if pool water is lost.

The staff's presentation said the new plant design assessment would be based on specific aircraft impact parameters, which would be spelled out in guidance. In general, the staff said, the aircraft impact characteristics would be based on a large, commercial aircraft used for long-distance domestic flights and fueled for such a flight. Other general characteristics include an impact speed and angle of impact that considers the ability of both experienced and inexperienced pilots to control the aircraft at a low altitude.

At the ACRS meeting, Jim Riccio, a nuclear policy analyst for Greenpeace, said he was "encouraged" that the staff "corrected the most glaring error" with the proposed rule -- excluding already certified designs. But he questioned whether allowing either the reactor designer or the applicant to conduct the aircraft impact assessment would diminish standardization of plants across different sites.

NRC's Reckley said the staff believes market forces will push the vendors to conduct the assessment. "We believe that the vendors will pick this up," he said. "So while it's true that if a vendor chooses not to do it, and each COL applicant had to do its own assessment, you could start to get some variations" in how the assessment is addressed. "But we don't really expect that to be the case," he said.

Created: July 22, 2008

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