Kwang Yong Jee

Separation of fission products from spent pressurized water reactor fuels by anion exchange and extraction chromatography for inductively coupled plasma atomic emission spectrometric analysis

A study has been carried out on the separation of fission products from spent pressurized water reactor (PWR) fuels and their quantitative determination using inductively coupled plasma atomic emission spectrometry (ICP-AES). Plutonium and uranium were separated from fission products using anion exchange and tri-n-butylphosphate (TBP) extraction chromatography, respectively. Americium was separated and fission products such as Sr, Ba, Cd, La, Ce, Pr, Nd, Sm, Eu, Gd and Y were quantitatively recovered using di(2-ethylhexyl)phosphoric acid (HDEHP) extraction chromatography. An ICP-AES/shielding system, which was specially designed and built for the analysis of radioactive materials, was employed and the analytical precision for all metal elements studied was found to be <5%. Three spent PWR fuels whose burnup rates were between 15,000 and 35,000 MWd/MTU were analysed and then the relation between the burnup and the quantity of the fission products was compared to that calculated by burnup code, ORIGEN 2.

XPS studies of superconducting Mo–Ru–Rh–Pd alloy

Abstract Superconducting quaternary alloys, Mo25Ru50Rh12.5Pd12.5, Mo30Ru45Rh12.5Pd12.5, Mo40Ru40Rh10Pd10 and Mo50Ru20Rh15Pd15 have been prepared using an arc melting furnace. X-ray photoelectron spectroscopic (XPS) measurements indicate that the binding energies of Pd 3d3/2 and 3d5/2 peaks increased by 0.5–0.9 eV. XPS measurements for several binary alloys, Pd1−xMox, Pd1−xRux, Pd1−xRhx and Pd1−xAgx (x=0.25, 0.5, 0.75 and 1.0) were also carried out to study the origin of the binding energy shifts of Pd 3d3/2 and 3d5/2 peaks. The binding energy shifts are found to be irrespective of the electronegativity of the constituent elements in the quaternary alloys, but rather closely related to the final state effects.

A Study on the Representative Sampling Survey for the Inspection of the Clearance Level for the Radioisotope Waste

Utilization facilities for radioisotope (RI) are increasing annually in South Korea, and the total number was 2,723, as of December 31, 2005. The inspection of a clearance level is a very important problem in order to ensure a social reliance for releasing radioactive materials to the environment. Korean regulations for such a clearance are described in Notice No. 2001–30 of the Ministry of Science and Technology (MOST) and Notice No. 2002–67 of the Ministry of Commerce, Industry and Energy (MOCIE). Most unsealed sources in RI waste drums at a storage facility are low-level beta-emitters with short half-lives, so it is impossible to measure their inventories by a nondestructive analysis. Furthermore, RI wastes generated from hospital, educational and research institutes and industry have a heterogeneous, multiple, irregular, and a small quantity of a waste stream. This study addresses a representative (master) sampling survey and analysis plan for RI wastes because a complete enumeration of waste drums is impossible and not desirable in terms of a cost and efficiency. The existing approaches to a representative sampling include a judgmental, simple random, stratified random, systematic grid, systematic random, composite, and adaptive sampling. A representative sampling plan may combine two or more of the above sampling approaches depending on the type and distribution of a waste stream. Stratified random sampling (constrained randomization) is proven to be adequate for a sampling design of a RI waste regarding a half-life, surface dose, undertaking time to a storage facility, and type of waste. The developed sampling protocol includes estimating the number of drums within a waste stream, estimating the number of samples, and a confirmation of the required number of samples. The statistical process control for a quality assurance plan includes control charts and an upper control limit (UCL) of 95% to determine whether a clearance level is met or not.© 2007 ASME

Derivation of the Korean radwaste scaling factor

The concentrations of several radionuclides in low and intermediate level radioactive waste (LILW) drums have to be determined before shipping to disposal facilities. A notice, by the Ministry of Science and Technology (MOST) of the Korean Government, related to the disposal of LILW drums came into effect at the beginning of 2005, with regards to a radionuclide regulation inside a waste drum. MOST allows for an indirect radionuclide assay using a scaling factor to measure the inventories due to the difficulty of nondestructively measuring the essential {alpha} and {beta}-emitting nuclides inside a drum. That is, a scaling factor calculated through a correlation of the {alpha} or {beta}-emitting nuclide (DTM, Difficult-To-Measure) with a {gamma}-emitting nuclide (ETM, Easy-To-Measure) which has systematically similar properties with DTM nuclides. In this study, radioactive wastes, such as spent resin and dry active waste which were generated at different sites of a PWR and a site of a PHWR type Korean NPP, were partially sampled and analyzed for regulated radionuclides by using radiochemical methods. According to a reactor type and a waste form, the analysis results of each radionuclide were classified. Korean radwaste scaling factor was derived from database of radionuclide concentrations. (authors)