Search Results

You are looking at 1 - 10 of 398 items for :

  • "Fission products" x
  • All content x
Clear All

Abstract  

Fission yields are especially well characterized for long-lived fission products. Modeling techniques incorporate numerous assumptions and can be used to deduce information about the distribution of short-lived fission products. This work is an attempt to gather experimental (model-independent) data on short-lived fission products. Fissile isotopes of uranium, neptunium, plutonium and americium were irradiated under pulse conditions at the Washington State University 1 MW TRIGA reactor to achieve ~108 fissions. The samples were placed on an HPGe (high purity germanium) detector to initiate counting in less than 3 min post irradiation. The data was analyzed to determine which radionuclides could be quantified and compared to the published fission yield data.

Restricted access

Abstract  

An analysis has been elaborated to determine the long-living γ-emitting fission products of uranium. It consists of a sodium bisulphate melt of the fission product solution or the U-fuel, followed by liquid-liquid extractions. Afterwards the isotopes are absolutely counted with a standardized 3″×3″ NaI crystal. The total γ-spectrum of the original fission product solution, taken with a NaI crystal or a Ge−Li detector, is also analyzed mathematically by mixed γ-spectrometry. From a short post-irradiation of the fission product solution the concentrations of both235U and238U are determined. The absolute amount of fission products related to the U-concentration allows the calculation of the percent atomic burn-up, the irradiation time, the cooling period, the flux of the reactor and the original degree of enrichment of the uranium.

Restricted access

Abstract  

The aim of the present work was to reveal the kinetics of the accumulation of some possible contaminant on the surfaces of structural materials (zirconium alloys and 08H18N10T stainless steel) in the primary circuit of Paks NPP. The kinetics of adsorption and desorption of iodide, caesium and cerium ions were investigated by quartz crystal microbalance (QCM) installed into a flow cell. The results on thin layers were confirmed by immersing experiments, using radiotracer technique and γ-spectrometry to detect the traced ions on the surfaces. Experiments were carried out in electrolyte solution which was similar to the cooling water. All measurements were carried out at room temperature. Both adsorption and desorption were found to be fast, taking only several seconds; time constants were also evaluated.

Restricted access

Rapid separations of corrosion and fission products

II. Ion exchange separations using A simple semiautomatic equipment

Journal of Radioanalytical and Nuclear Chemistry
Authors: M. Szlaurová, D. Vančo, P. Galan, and M. Fojtík

Abstract  

The separation procedure for the mixture of radiohygienically important radionuclides using a set of ion exchange columns with inorganic ion exchangers and seminautomatic SA—7100 separation equipment has been elaborated. Conditions required for the selective separation of representative radionuclides of corrosion and fission products are given. Quantitative and selective separation, verified by gamma spectrometry, has been performed in one run within 30 min.

Restricted access
Journal of Radioanalytical and Nuclear Chemistry
Authors: H. Natsume, H. Umezawa, T. Suzuki, F. Ichikawa, T. Sato, S. Baba, and H. Amano

Abstract  

A scheme for the sequential separation of fission products has been developed on the basis of ion-exchange techniques. It consists of a main cation-exchange process for group separation and subsidiary processes of cation or anion exchange for further separations or purifications of the individual fission products. By the present method, Zn, Rb, Sr, Y, (Zr), Mo, Pd, Cd, Te, Cs, Ba, La, Ce, Pr, Nd, Pm, Sm, Eu and Tb can be separated simultaneously from an irradiated uranium sample. Of these, alkali, alkaline earth and rare earth metal ions are separated quantitatively. A polarographic method was applied to determine the recoveries of Zn, Mo, Pd, Cd and Te, which were not separated quantitatively.

Restricted access

Rapid separations of corrosion and fission products

I. Selective liquid-liquid extractions with metal diethyldithiocarbramates

Journal of Radioanalytical and Nuclear Chemistry
Authors: D. Vančo, M. Fojtík, M. Szlaurová, and P. Galan

Abstract  

A separation scheme of a complex mixture of radiohygienically important radionuclides of corrosion and fission products has been worked out. Rapid separation by means of solvent extractions with metal (sodium, antimony, zinc) diethyldithiocarbamates has been achieved. Chloroform containing metal diethyldithiocarbamates has been used as the organic phase. The procedure permits to separate selectively the representative radionuclides. The selectivity of separation was verified by gamma spectrometry.

Restricted access

Abstract  

Investigations on the disintegration rate of fission products of238U and239Pu are presented. The intensity of the - and -radiation of fission products were measured continuously in an interval of 1–1300 hours following the fission, offering the possibility for determining the general and specific characteristics of the individual fission products. A universal measuring procedure was elaborated for the rapid in situ determination of the dosimetric features of fission products, which is suitable for the accurate evaluation and prediction of external absorbed dose even in case of fission products of various origin and unknown composition.

Restricted access
Journal of Radioanalytical and Nuclear Chemistry
Authors: K. Takamiya, T. Fukunishi, R. Tsujito, S. Fukutani, T. Takahashi, S. Shibata, and S. Uchida

Abstract  

The adsorption behavior of fission products to various soils was studied using a multitracer. The multitracer was prepared by neutron irradiation of 235U. Distribution coefficients of fission products were obtained for seventeen kinds of Japanese soils. It was found that zirconium, niobium, and rare earth elements show high distribution coefficients for all soil samples, however, elements like alkali metals show varied values.

Restricted access

Abstract  

A method of137Cs isolation from strongly, acidic solutions of fission products is described, in which vanadyl ferrocyanide is used as a selective ion exchanger for cesium. The effects of the acidity of medium and the carrier concentration on the quantitative yield of separation have been studied and convenient conditions have been found for137Cs isolation from the solution of fission products formed after irradiating uranium with neutrons.

Restricted access

Abstract  

Specific activities of radioactive elements at the time of chemical separation from fission product mixtures produced by thermal neutron fission of235U were computed byBateman's and other equations on an electronic computer. Computations were made for two fission times: fission was assumed to be complete in a few minutes in one case, and over a period of a year in the other case. It was also assumed that each element was separated instantly after allowing the fission products to decay for 1∼10 000 000 hrs (1 140 years). The computations were applied to 12 important elements: Ru, Zr, Nb, Cs, Sr, Pm, Tc, Ba, La, Ce, Kr and Y. Results are given as a diagram for each element. The diagrams are intended to be helpful in the chemical processing of a large quantity of fission products, and industrial or tracer application of these elements.

Restricted access