POSSIBILITIES FOR REORIENTATION THE ACTIVITY
OF HEAVY WATER PLANTS

F. Pop1, C. Croitoru1, Gh. Tiţescu1, I. Ştefănescu1, I. Hodor2, S. Cuna2  

1National R&D Institute for Cryogenics and Isotopes Technologies ICSI Ramnicu Valcea, Romania,Uzinei Street no.4 P.O. Box 10
2 National R&D Institute of Isotopic and Molecular Technologies Cluj –Napoca, Romania Donath Street no. 71-103, P.O.Box 700

Oxygen-18 separation is possible by distillation and electrolysis of water, cryogenic distillation of nitric oxide, thermal diffusion, chemical exchange reactions and membrane distillation. At present in the world are applied water distillation, cryogenic distillation of nitric oxide and thermal diffusion. Water distillation is used at industrial scale. If there is a source of water which has the 18O concentration greater than the natural abundance, the production cost is lower; such a source is the heavy water. Current worldwide tendency is to turn to good account all existent availability. In Romania, there is such an availability at Drobeta Turnu Severin, at the heavy water factory and at Ramnicu Valcea, at the former heavy water pilot plant. 
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, 18O concentration of produced heavy water, maximum its concentration of pre-concentrate obtained on distillation line and the separation cascade dimensions (for 95 at. % 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 from the Romanian Heavy Water Factory. 
Single stage separation factor of 18O is much lower than in the case of deuterium separation by the same method, for this reason 18O being an expensive product.