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Proliferation Resistance

HTMR Ltd.’s HTMR100 reactor operates on a much longer burn-up fuel cycle of pebble fuel when compared to conventional nuclear reactors. No thorium fuel cycle involving the separation and recycle of 233U would approach the proliferation resistance of unprocessed spent fuel.


HTMR100 has been designed for a single pass of pebbles through the core, therefore eliminating all the complexities of recirculation. This fueling concept is called Once-Through-Then-Out, or OTTO cycle. An important non-proliferation characteristic of the OTTO cycle is the long-time of pebbles reside inside the core, making it impossible to divert partially burnt fuel for extraction of weapons grade uranium/plutonium. By the time the pebbles are extracted from the core, the remaining fissile material (mostly 233U in the case of thorium based fuel) is contaminated with a considerable amount of absorbent material (namely 234U). Another strong deterrent with 233U as a fissile material for proliferation purposes is that the spent fuel contains an admixture of 232U, whose decay products produce penetrating gamma rays. This spent fuel containing 232U is undesirable as weapons material by virtue due to the fact that their gamma emissions bring with them the potential for significant radiation doses and shielding requirements during weapons proliferation.


HTMR Ltd.’s commitment of using a proliferation resistant technology naturally extends to a philosophy not supportive of recycling. The HTR technology, characterized by relatively high burn ups, converts the fissile material in situ to nuclear waste before the pebbles are extracted. In addition, the silicon carbide coating of the fuel kernels can be considered a first step in immobilization (vitrification) of nuclear waste, making HTMR100 fuel less suitable for reprocessing.

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