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Core Description

Reactor Systems



The MITR-II, the major experimental facility of the NRL, is a heavy-water reflected, light-water cooled and moderated nuclear reactor that utilizes flat, plate-type, finned, aluminum-clad fuel elements. The average core power density is about 70 kW per liter. The maximum fast and thermal neutron flux available to experimenters are 1.2x1014 and 6x1013 neutrons/cm2-s, respectively. Experimental facilities available at the MIT research reactor include two medical irradiation rooms, beam ports, automatic transfer facilities (pneumatic tubes), and graphite-reflector irradiation facilities. In addition, several in-core experimental facilities(ICSAs) are available. It generally operates 24/7, except for planned outages for maintenance. The MITR-II encompasses a number of inherent (i.e., passive) safety features, including negative reactivity temperature coefficients of both the fuel and moderator; a negative void coefficient of reactivity; the location of the core within two concentric tanks; the use of anti-siphon valves to isolate the core from the effect of breaks in the coolant piping; a core-tank design that promotes natural circulation in the event of a loss-of-flow accident; and the presence of a full containment. These features make it an exceptionally safe facility.