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We herein present a suquential procedure for separation of nuclides such as 55Fe, 94Nb, 59,63Ni, 90Sr, and 99Tc from activated carbon and stainless steel samples orignating from low and intermediate level of radioactive waste. Initially, iron was removed through the precipitation of Fe(OH)3 upon the addition of NH4OH. The recoveries of Fe and Nb in the precipitate were 98.4 ± 2.9 and 98.5 ± 0.52%, respectively, while those of Ni, Re, and Sr in the supernatant were 74.0 ± 4.0, 96.7 ± 1.2, and 79.6 ± 1.2%, respectively. However, due to the especially low recovery of Re from the supernatant following anion exchange chromatography, the Fe precipitate was removed after the separation of Re by anion exchange chromatography. Our results indicate that this procedure is suitable for providing pure nuclides from waste samples to allow the measurement of their radioactive activities.

A radiological safety assessment study was performed for the transportation of low level radioactive wastes which are temporarily stored in Korea Atomic Energy Research Institute (KAERI), Daejeon, Korea. We considered two kinds of wastes: (1) operation wastes generated from the routine operation of facilities; and (2) decommissioning wastes generated from the decommissioning of a research reactor in KAERI. The important part of the radiological safety assessment is related to the exposure dose assessment for the incident-free (normal) transportation of wastes, i.e., the radiation exposure of transport personnel, radiation workers for loading and unloading of radioactive waste drums, and the general public. The effective doses were estimated based on the detailed information on the transportation plan and on the radiological characteristics of waste packages. We also estimated radiological risks and the effective doses for the general public resulting from accidents such as an impact and a fire caused by the impact during the transportation. According to the results, the effective doses for transport personnel, radiation workers, and the general public are far below the regulatory limits. Therefore, we can secure safety from the viewpoint of radiological safety for all situations during the transportation of radioactive wastes which have been stored temporarily in KAERI.

A procedure for the rapid separation of 99Tc, 90Sr, 55Fe, 94Nb, and 59,63Ni in radioactive waste samples was developed for measuring their activity. After separating 99Tc on an anion-exchange resin column, 90Sr was separated as 90Sr(CaC2O4) co-precipitates, and 59,63Ni, 55Fe, and 94Nb were sequentially separated on an anion-exchange resin column in the presence of oxalate. The separated 90Sr and 59,63Ni were further purified on extraction chromatographic resin columns, respectively. The chemical yields of the separation procedure for Re, Sr, Fe, Nb, and Ni, which were added as chemical carriers, are 99.3 ± 0.3 %, 94.8 ± 0.6 %, 93.3 ± 1.2 %, 95.3 ± 1.9 %, and 92.6 ± 0.6 %, respectively. The separation of these radionuclides from sixteen radioactive waste samples required only seven person-days.

We developed a rapid quantification method of Pu, Am, and Cm in low- and intermediate-level radioactive waste using TRU resin, alpha spectrometry, and thermal ionization mass spectrometry for radioactive waste disposal. In particular, we focused on the optimization of sample preparation methods for alpha spectrometry and mass spectrometry to reduce the analysis time. The optimized method used Am and Pu stripping solutions for micro-coprecipitation and showed good recovery and alpha spectrum resolution for alpha counting. In addition, appropriate selection of Pu elution solution decreased the sample preparation time for thermal ionization mass spectrometry measurements.

It is impossible to detect 14C and 3H by direct methods such as γ-spectroscopy because they are pure b-emitters and thus they are classified as hard to measure nuclides (HTM). In this paper the analysis results of 14C and 3H in the low level radioactive wastes (LLWs), including spent ion exchange resin, evaporated bottom and sludge are presented. The LLWs were generated by three nuclear power plants (NPPs), in Korea all with pressurized water type reactors (PWRs). A simultaneous separation procedure for 14C and 3H in LLWs was established by wet oxidation-acid stripping. A liquid scintillation analyzer was used for the measurement of 14C and 3H. It was found that the recovery of 14C and 3H was 82-99 and 78-103%, respectively, by wet oxidation-acid stripping with diluted standard solutions. At the lowest injection of 14C and 3H, i.e., at 1.44 Bq for 14C and 1.22 Bq for 3H, the minimum detectable activity (MDA) of 14C and 3H was calculated as 0.88 and 0.78 Bq/g, respectively, for the minimum allowable sample weight, using wet oxidation and 16 wt% H2SO4 acid. By the wet oxidation-16 wt% H2SO4 stripping method no interfering nuclides were detected in the trapping solution of 14CO2 and the distillate of 3H. The activity concentration range of 14C in the analyzed samples, i.e., spent ion exchange resin, evaporated bottom and sludge, was 0.17-110,000, 8.4-1380 and 0.1-10,006 Bq/g, respectively, and that of 3H in the same was from no detectable to 769, 134-14,383 and 0.7-4820 Bq/g, respectively.

In the original publication, the units of the activities in Tables 2 and 3 are incorrect and they need to be corrected to Bq/kg. In addition, ‘Activity of Am’ in the right column in Table 3 needs to be corrected to ‘Activity’. Therefore, corrected Tables 2 and 3 are given below: Table 2 Activity measurement of Am and Cm isotopes in the radioactive dry waste sample using alpha spectrometry Sample # Activity (Bq/kg) Am recovery (%) Am Cm Cm

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)