The MHTGR is an advanced reactor concept being developed under a cooperative program involving the U.S. Government, the nuclear industry, and the utilities. The design utilizes the basic HTGR features of ceramic fuel, helium coolant, and a graphite moderator. However, the specific size and configuration are selected to utilize the inherent characteristics of these materials to develop passive safety features that provide a significantly higher margin of safety than current generation reactors.The design meets the U.S.Environmental Protection Agency's Protective Action Guidelines at the site boundary, hence precluding the need for sheltering or evacuation of the public during any licensing basis event. This safe behavior is not dependent upon operator action and is insensitive to operator error.The MHTGR Licensing Plan agreed to with the U.S. Nuclear Regulatory Coimtission (NRC) is discussed with particular attention to the framework of the preapplication review. The objective and scope of each key document prepared for the NRC review is presented. A summary is provided of the safety response to events challenging the functions relied on to retain radionuclides within the coated fuel particles. The regulatory interaction process and results are discussed through the NRC staff, NRC contractor, and ACRS reviews.2.

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The MHTGR is an advanced reactor concept being developed under a cooperative program involving the U.S. Government, the utilities and the nuclear industry. The programs objective is the development of an environmentally safe, reliable, and economic nuclear power option for the USA and other nations of the world. HTGR design features, such as the ceramic fuel, helium coolant, and graphite moderator, are incorporated into the MHTGR reference plant design which incorporates four 350 MW(t) reactor modules. This papers objective is to describe those plant features, which minimize the environmental impact of MHTGR operation through efficient energy production, management of normal plant non-radioactive/radioactive effluents, and inherent characteristics and passive safety features which ensure benign plant site suitability source terms.

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