A comparison between the three 99Mo production methods (the fission method, the solid irradiation method and the solution irradiation method) is shown in Table 1, assuming the 99Mo production in JMTR, which is a tank-type reactor.

1.1 Fission method ((n, f) method)

In the conventional fission method ((n, f) method), high-enriched uranium targets are irradiated with neutrons in a testing reactor, and 99Mo is produced by the 235U (n, f) 99Mo reaction. Most of the world supply of 99Mo is produced by the (n, f) method since 99Mo with a high-level specific activity of 370 TBq/ g-Mo is obtained. However, the method has problems about the nuclear nonproliferation and the generation of a significant amount of radioactive waste including Fission Products (FPs) and Pu. Caused by the radioactive waste, the separation process of 99Mo is too complex, and 99Mo production with the (n, f) method needs expensive facilities and extreme care to avoid contamination with FPs. The 99Mo production cost by this method achieves 57 US$/37 GBq (Boyd, 1997), and it is too expensive.