A simple and reliable method for the determination of222Rn concentration in natural water using a liquid scintillation counting technique was investigated. Water sample (50ml) containing222Rn was directly mixed into emulsive liquid scintillator (50 ml), followed by the spectrometric measurements by a multichannel pulse height analyzer coupled to a low background liquid scintillation counter. Weak quenching effect due to the increase of water fraction and the ionic constituents did not bother the determination of low-level222Rn concentration because the liquid scintillationspectrometry could easily distinguish the alphaparticle spectrum even in quenched samples. Since the present procedure is not necessary for the correction of the recovery yield of222Rn, the experimental error included is very small in comparison with the widespread extraction method of222Rn with organic solvent. The detection limit of222Rn concentration was estimated to be about 74 mBq/l (triple the standard deviation of background counting) in a fixed counting time of 100 min.
In order to incinerate the emulsive liquid scintillator waste containing32P, 35S and45Ca, application of demulsion by salt out technique for pre-treatment had been experimentally investigated. As the results, it was obtained that about 99% of aqueous content was removed from the liquid waste and their viscosities were being less than 5 cP. Then, more than 95% of radioactivities of the above nuclides were simultaneously removed together with aqueous content, by using 4 M NaCl and 3 M (NH4) 2CO3as salt out reagents for the liquid scintillator wastes containing inorganic labeled compounds such as KH232PO4, H235SO4and45CaCl2, and organic labeled compounds such as32P-ATP and35S-methionine respectively. Still, as other common conditions for demulsion, it was found that suitable factors were mixing time of 2 min and temperature of 40-50°C.