Irradiation volume recovery

On irradiation the t-t-t-dye is isomerized to its c-t-c-isomer this conformational change causes a decrease of dye-polymer interactions resulting in a gel contraction of 1.2%, i.e. a change in volume of about 3.6%. In the dark the gel recovers its original dimensions the rate of recovery is a function of temperature and parallels the increase of optical density of chrysophenine at 400 nm. 

Liquid targets are used in the production of many PET radionuclides, particularly 18F and 13N. Fluorine-18 is produced by using a liquid target of lsO-enriched water and so is 13N by using 5 nM ethanol in water. The target volume is small in the range of 3-15 ml under high pressure. Since lsO-water is expensive, it is customary to recover it for subsequent irradiation and the method of recovery is described in the later section. 

Amayev A D, Kryukov A M and Sokolov M A (1993), Recovery of the transition temperature of irradiated WWER 440 vessel metal by annealing, pp. 369-379 in Radiation Embrittlement of Nuclear Reactor Pressure Vessel Steels An International Review (Fourth Volume), ASTM STP1170, L E Steele, ed., American Society for Testing and Materials, Philadelphia, PA. 

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