Possibilities for reorientation of activity in a heavy water plant

Full text: Oxygen-18 separation is carried out by distillation and electrolysis of water, cryogenic distillation of nitric oxide, thermal diffusion, chemical exchange reactions and membrane distillation. At present in the world water distillation, cryogenic distillation of nitric oxide and thermal diffusion procedures are applied. Water distillation is used at industrial scale. There is a source of water which has the 18O concentration greater than the natural abundance and the production cost is lower. Such a source is the heavy water. Current worldwide tendency is to turn to good account all existent availabilities. In Romania, there is such an availability at the heavy water plant at Drobeta Turnu Severin and at the former heavy water pilot plant at Ramnicu Valcea. This paper presents data regarding the possibilities to use one distillation line for oxygen-18 production as pre-concentrates or finite products. Using a simulation program, the 18O concentration of produced heavy water, the maximum concentration of pre-concentrate obtained on distillation line and the separation cascade dimensions (for 95 % 18O production) were calculated. It was assumed that the first and second stage have the same dimensions like those in place at the distillation plant at the Romanian Heavy Water Plant. Single stage separation factor of 18O is much lower than in the case of deuterium separation by the same method. For this reason, 18O is an expensive product. (authors)