@misc{oai:repo.qst.go.jp:00072270,
 author = {川端, 方子 and 本石, 章司 and 橋本, 和幸 and 初川, 雄一 and 太田, 朗生 and 椎名, 孝行 and 佐伯, 秀也 and 竹内, 宣博 and 永井, 泰樹 and 川端 方子 and 本石 章司 and 橋本 和幸 and 初川 雄一 and 太田 朗生 and 佐伯 秀也 and 永井 泰樹},
 month = {Sep},
 note = {Technetium-99m (T1/2= 6 h) is the most commonly used radioisotope in nuclear medicine accounting for over 80% of diagnostic procedures worldwide. This level of usage and the variety of 99mTc radiopharmaceuticals come from the availability of parent nuclide 99Mo (T1/2= 66 h) which is abundantly generated in nuclear reactor using a highly enriched uranium, and so is called “fission 99Mo”. A series of unexpected nuclear reactor shutdown since 2007 however, caused a global shortage of 99Mo and was recognized as an urgent need to develop an alternative 99Mo production method to ensure a secured supply long into the future [1]. Alternative production methods are available, but these rely on the development of appropriate processing technology to accept the specific activity of 99Mo much lower than that of fission 99Mo.
The current approach uses accelerator generated neutrons to produce 99Mo via the 100Mo(n,2n)99Mo reaction where fast neutrons are generated by 40 MeV deuterons bombarded to the carbon converter [2]. A 106g sample of 100MoO3 one third of which was irradiated 14 MeV neutron at the Fission Neutronics Source (FNS; a D-T neutron source) of the Japan Atomic Energy Agency (JAEA), was divided into platinum crucibles to be vertically fitted within the high temperature area of a tubular electric furnace (a in Fig. 1). The furnace is heated beyond 800 oC in the sample area with moist O2 as a carrier gas. 99mTc generated from 99Mo in the molten 100MoO3 in the crucibles is rapidly released from the sample as a gaseous species which is then transported and concentrated in the downstream quartz tube at low temperature around 300 oC (e in Fig. 1). The principle behind the methodology is described elsewhere [3]. Concentrated 99mTc was washed with 18 mL of 0.1 M NaOH and passed through a cation exchange column and alumina column to adjust pH and adsorb 99mTc, respectively.  The columns were washed with 20 mL of ultrapure water and 99mTc was eluted with a few mL of saline solution from the alumina column. Overall, the separation efficiency was more than 85% on average. Same thermo-separation procedure was repeated using over 100 g of 100MoO3 sample to assess the recovery yield of 100MoO3. Several grams of sublimated 100MoO3 were lost from the crucibles and recrystallized at a temperature under melting point of MoO3 during the separation. Most of them were recrystallized in the quartz holder (c in Fig. 1). The 100MoO3 crystals were collected by washing with pure water from the holder and the other quartz glassware containing MoO3. The collected crystal was evaporated to dryness to measure its mass.  100MoO3 remaining in the crucibles were inverted and heated in the same electric furnace. Molten 100MoO3 was collected into a quartz tube with a 30 mm diameter to mold a sample for the next neutron irradiation. 100MoO3 was successfully collected with the recovery yield > 95%.
\nReference
1) T.Ruth, Nature 457, 29 (2009)
2) Y. Nagai and Y. Hatsukawa, J. Phys. Soc. Jpn. 78, 033201 (2009).
3) Y. Nagai, M. Kawabata, N. Sato, K. Hashimoto, H. Saeki, and S. Motoishi, J. Phys. Soc. Jpn. 83, 083201 (2014)., The Ninth International Conference on Nuclear and Radiochemistry},
 title = {99Mo generation by accelerator-driven neutrons and thermo-separation of 99mTc},
 year = {2016}
}