Within 3 years after October 24, 1992, the Secretary shall solicit proposals for carrying out the preliminary engineering design of not more than 2 prototype advanced nuclear reactor technologies developed by the Department of Energy, other than advanced light water reactor technologies, necessary to support a decision on whether to recommend construction of a prototype demonstration reactor with the characteristics described in section
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(a) of this title. Proposals submitted under this subsection shall be for modular design concepts of sufficient size to address requirements related to the certification of a standardized design.