Multielement determination in reference materials of diet and its relatedsamples has been studied by a k 0 based neutron-induced prompt gamma-ray analysis(PGA) by using cold and thermal guided neutron beams of JRR-3M at JAERI. Hydrogen,B, C, N, Na, S, Cl, K and Ca were determined in the reference materials ofNIES and NIST typical diet and milk powder samples. Analytical results ofthe NIST Standard Reference Materials agreed with the certified values towithin 7%.
A neutron-induced prompt -ray analysis (PGA) has become widely utilized due to the improved analytical sensitivities and detection limits especially by using low energy guided neutron beams. Current studies on the low energy neutron guided beam PGA are reviewed. Historical backgrounds, current analysis systems, advantages when compared with conventional NAA, standardization for elemental determination and analytical applications in JAERI of the guided beam PGA are described.
Trace determination of phosphorus has been studied using neutron activation analysis. Radioactivity of 32P in tri-n-octylamine phosphomolybdate complex was measured using liquid scintillation counting by extracting the complex into xylene. Phosphorus can be quantitatively determined from 16.7 to 600 g/10 ml by using the radiochemical analysis method described.
Extraction-chromatographic separation of uranium from fission products was performed using undiluted tributyl phosphate sorbed
on Chromosorb W as a stationary phase, and nitric acid (1: 3) as a mobile phase. Most of the fission products that contributed
greatly to the radiation level of the sample passed through the column; this effected considerable decontamination. Uranium
retained on the column was quantitatively recovered by elution with water.
The extraction of UO
, Am3+, and Th4+ by 1-phenyl-3-methyl-4-benzylpyrazolone with crown ethers was studies using 0.1M (NaClO4) aqueous phase and toluene. The crown ethers were 12C4, 15C5, 18C6, DB18C6 and DCH18C6. The synergic equilibrium constant did not show correlation between the cationic radii and the ether cavity size nor did the values follow a simple order of ether basicity. The ether basicity, steric effects, and the number of ether oxygens bound to the cation are the combined factors which seemingly determine the pattern of M(PMBP)n—CE interaction.
A solvent extraction method is presented for the separation of95Nb from95Zr.95Nb is extracted quantitatively into a chloroform solution of α-benzoinoxime from 5N hydrochloric acid solution. By following the recommended procedure, a separation factor higher than 104 is achieved.95Nb can be back-extracted into concentrated hydrochloric acid. The radiochemical purity of the95Nb separated has been ascertained by half-life and γ-ray energy measurements. The whole procedure takes less than 20 min.
Methods were developed for the separation of tungsten from molybdenum by liquid-liquid extraction and extraction chromatography
using thiocyanate and a quaternary ammonium salt, Zephiramine. Tungsten was extracted into chloroform as an ion associate
of tungsten(V)-thiocyanate complex and Zephiramine cation was retained on a column of Teflon powder coated with Zephiramine,
but molybdenum(III) was neither extracted nor retained. The extraction chromatographic method was successfully applied to
the determination of trace amounts of tungsten in molybdenum by neutron activation analysis.
In order to determine multiple elements by k0 standardization-based neutron induced prompt gamma-ray analysis (PGA), measurements and evaluation of k0 factors for the elements have been performed. The k0 factors using Cl as a comparator for 27 elements, which are effective for the analysis by PGA, were measured with precision almost less than 3% using the cold and thermal guided neutron beams at JRR-3M. The accuracy of the k0 factors were better than 10% except for the non-1/v elements of Cd and Sm. Neutron spectrum correction is necessary for common use of k0 factors of the non-1/v elements.
Neutron spectra were measured by the time of flight method using a rotating disk chopper system in the JRR-3M prompt gamma
ray analysis system. Effective g-factors for non-1/v elements such as Cd, Sm and Gd were calculated from the measured neutron spectra and the neutron cross section data, and
they was used for correcting the k0-factors. The resulting k0-factors for the cold and thermal neutron beams agreed within 10%. Furthermore, the prompt gamma ray emission probabilities
of Cd, Sm and Gd were derived from the corrected k0-factors using other relevant physical constants.
Recommended k0-factors for gamma-lines of 24 elements useful for neutron-induced prompt gamma-ray analysis (PGA) and which are not influenced
by neutron spectrum differences were obtained from the k0-factors measured with the cold and thermal neutron guided beams of JRR-3M, by statistical calculation. The prompt gamma-ray
emission probabilities were derived from the recommended k0-factors using atomic weight, isotopic abundance and thermal neutron capture cross section all related to the k0-factors, for which one can obtain accurate data. The derived gamma-ray emission probabilities for the light elements (H to
Ca) agreed well within ±10% with those of the ENSDF values, which reflect recent data while the agreement for heavy elements
(Ti to Pb) was ±40% with those of the ENSDF, which are still composed of old data.