This paper deals with a rapid method to determine radionuclides in reactor coolant by anion, cation, and anion-cation exchange membranes. A high pressure filtration device was established to simulate the THOR cooling water sampling system by means of several membranes mentioned above. The experimental results indicate that the adsorption efficiency of each membrane for several radionuclides is /1/ >95% with cation exchange membrane for Zn, Co, Na, Mn, Cu, Cs, Ba, La, W etc., /2/ >98% with anion exchange membrane for I, and /3/ <98% with anion-cation exchange membranes for Fe and Cr. The results are obtained using cooling water of Tsing Hua Open-Pool Reactor and the following radionuclides were identified:99mTc,140Ba,140La,51Cr,131I,58Co,60Co,54Mn,46Sc,59Fe,24Na, etc.
The concentrations of hydrogen peroxide formed in the coolant due to radiolysis were studied during THOR operation at 1 MW. The relation between doses and hydrogen peroxide formation in a neutron-gamma mixed field was investigated. The initial concentration was 2.3×10–5 g/ml at the beginning of reactor operation, and then it was increased rather rapidly at the first 9 h. The increasing rate was slowed down till the end of 30 h operation. The maximum concentration of hydrogen peroxide was found to be 4.7×10–5 g/ml, and its decrease followed the exponential curve.
A radiochemical method has been developed for the determination of99Tc in low-level radioactive, waste from nuclear facilities, using99mTc as an internal tracer. Radioactive contaminants were removed by carrier hydroxide precipitation and chelating extraction with NaDDC/CHCl3 system at pH 4. The final technetium was chelated with NaDDC in 3N HCl solution and extracted selectively into chloroform. The average of radiochemical recovery for various types of LLW sample is about 90%. The decontamination factors for most radioactive nuclides are higher than 105. The detection limit for99Tc in a sample of about 10 g is 0.17 pCi/g (6.5 Bq·kg–1) for a 100-minute count.
Authors:M. Yang, P. Chen, C. Tseng, S. Yeh, and P. Weng
Dinonylnaphthalene sulfonic acid (HD) has been used as a preconcentrating agent to enrich trace metal ions and to separate
the interfering elements such as Na, K, Cl and Br which normally exist in the natural aqueous systems. Experiments were performed
by extracting the ions in the aqueous medium with HD in n-hexane and subsequently back-extracted into a minimal volume of
acid solution. Factors influencing the extraction efficiency of the ions of interest were investigated. The preconcentration
technique developed in this study was applied to the determination of trace elements in biological and natural water samples
by neutron activation analysis.