International Topical Meeting on Nuclear Research Applications and Utilization of Accelerators

4-8 May 2009, Vienna

Analysis of Molybdenum-99 Production Capability in the Materials Test Station

E.J. Pitcher

Los Alamos National Laboratory, Los Alamos, United States of America

Corresponding Author: pitcher@lanl.gov

The United States of America currently relies on foreign suppliers to meet all of its needs for
molybdenum-99 used in medical diagnostic procedures. The current US demand exceeds 5,000 six-day curies (Ci) per week. A six-day Ci is a unit of measure used by the industry, which is the amount of Mo-99 remaining in the generator six days after delivery to the medical facility. The recent decision by the Atomic Energy of Canada, Limited to close the MAPLE reactors has led to renewed interest within the USA in assessing alternate sources for Mo-99, particularly domestic sources. The proposed Materials Test Station (MTS) could potentially serve this mission.

The MTS will be a fast neutron spectrum irradiation facility for testing candidate fast reactor fuels and materials. It is a spallation source driven by a 1 MW, 800 MeV proton beam, located at the Los Alamos Neutron Science Center (LANSCE) within Los Alamos National Laboratory. The facility is slated to start operation in 2013.

Two methods of Mo-99 production have been evaluated in this study. The first is through the
traditional ²³⁵U(n, f)⁹⁹Mo reaction, the second is via the ⁹⁹Tc(n, p)⁹⁹Mo reaction. The first is best carried out in a thermal spectrum, while the second, which has a threshold energy of 0.58 MeV, requires a very hard neutron spectrum.

Two target material options have been explored for Mo-99 production in the Materials Test Station (MTS): low enriched uranium (LEU) and Tc-99. For LEU, scoping calculations indicate that MTS can supply nearly half of the current US demand with only minor neutronic impact on the MTS primary mission. However, there may be significant impact from an operations standpoint (permitting, safety, and security). For the Tc-99 option, the MTS could produce about one-tenth of the US demand.

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