Molybdenum-99 is one of the most important radionuclides for medical diagnostics. In 2015, the International Atomic Energy Agency organized a round-robin exercise where the participants measured and calculated specific saturation activities achievable for the 98 Mo(n,c) 99 Mo reaction. This reaction is of interest as a means to locally, and on a small scale, produce 99 Mo from natural molybdenum. The current paper summarises a set of experimental results and reviews the methodology for calculating the corresponding saturation activities. Activation by epithermal neutrons and also epithermal neutron self-shielding are found to be of high importance in this case.

The Dalat Nuclear Research Reactor (DNRR) with the nominal power of 500 kW was reconstructed and upgraded from the USA 250-kW TRIGA Mark-II reactor built in early 1960s. The renovated reactor was put into operation on 20th March 1984. It was designed for the purposes of radioisotope production (RI), neutron activation analysis (NAA), basic and applied researches, and nuclear education and training. During the last 30 years of operation, the DNRR was efficiently utilized for producing many kinds of radioisotopes and radiopharmaceuticals used in nuclear medicine centers and other users in industry, agriculture, hydrology and scientific research; developing a combination of nuclear analysis techniques (INAA, RNAA, PGNAA) and physic-chemical methods for quantitative analysis of about 70 elements and constituents in various samples; carrying out experiments on the reactor horizontal beam tubes for nuclear data measurement, neutron radiography and nuclear structure study; and establishing nuclear training and education programs for human resource development. This paper presents the results of operation and utilization of the DNRR. In addition, some main reactor renovation projects carried out during the last 10 years are also mentioned in the paper.

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Lutetium-177 (177Lu) radioisotope used for medical purposes has been produced at the Dalat Nuclear Research Reactor during 2012-2014. The product was synthezed by the activation reaction 176Lu (n,γ) 177Lu. The target was Lutetium oxide with an abundance of 176Lu being 2.59% and the irradiation was conducted with a neutron flux of 2.1013 n cm-2 s-1. The activity of the 177Lu product was 39,59 Ci g-1 after 108 hous of the irradiation. The yield of this method was much higher compared to those of the reaction 176Yb(n, γ)177Yb → 177Lu + β- which for the same time could be 15mCi/50mg only. Because of low specific radioactivity the preparation of 177Lu made from the activation of 176Yb cannot be applied for the medical purposes. Additionally, the separation yield of 177Lu from 177Yb is rather low, it is usualy of approximately 70%.

After reconstruction, the Dalat Nuclear Research Reactor (DNRR) was inaugurated on March 20th, 1984 with the nominal power of 500 kW. Since then the production of radioisotopes and labelled compounds for medical use was started. Up to now, DNRR is still the unique one in Vietnam. The reactor has been operated safely and effectively with the total of about 37,800 hrs (approximately 1,300 hours per year). More than 90% of its operation time and over 80% of its irradiation capacity have been exploited for research and production of radioisotopes. This paper gives an outline of the radioisotope production programme using the DNRR. The production laboratory and facilities including the nuclear reactor with its irradiation positions and characteristics, hot cells, production lines and equipment for the production of Kits for labelling with 99mTc and for quality control, as well as the production rate are mentioned. The methods used for production of 131I, 99mTc, 51Cr, 32P, etc. and the procedures for preparation of radiopharmaceuticals are described briefly. Status of utilization of domestic radioisotopes and radiopharmaceuticals in Vietnam is also reported.