Michio Hoshi

The characteristics of the prompt gamma-ray analyzing system at the neutron beam guides of JRR-3M

Abstract A reactor-neutron-induced prompt γ-ray analyzing system was constructed at JRR-3M. The system can be set at cold and thermal neutron beam guides with a neutron flux at the sample position of 1.1 × 10 8 and 2.4 × 10 7 n cm −2 s −1 , respectively. The system was designed to achieve the lowest γ-ray background. This is done by using lithium fluoride tiles as neutron shielding, by placing the samples in a He atmosphere, and by using a Ge-BGO detector system for Compton suppression. The γ-ray spectrometer is equipped to acquire three modes of spectra simultaneously: single mode, Compton suppression mode, and pair mode in an energy range of up to 12 MeV. Due to the cold neutron guide beam and the low background system, sensitivities and detection limits better than those in other PGA systems have been achieved. For typical elements such as H, B, Cd, and Gd, analytical sensitivities with the cold neutrons are 10 to 18 times higher, and detection limits are lowered by factor of 6 to 8, compared to the case with thermal neutrons under the same geometrical condition. Detection limits down to a range of 2 to 7 ng were recorded for B, Cd, Sm, and Gd by the cold neutrons. Hydrogen, one of the most important elements in material studies, could be detected down to 1.0 and 2.8 μg by cold and thermal neutrons, respectively.

PROMPT GAMMA-RAY ANALYSIS USING COLD AND THERMAL GUIDED NEUTRON BEAMS

A permanent and stand-alone neutron-induced prompt γ-ray analysis (PGA) system, usable at both cold and thermal neutron beam guides of JRR-3M has been constructed. The characteristics of the system, including neutron beam and γ-ray spectrometer were measured. Owing to the absence of fast neutrons and the low γ-ray background, analytical sensitivities and detection limits better than those in other PGA systems have been achieved. Analytical results of ten elements in Standard Reference Material of Coal Fly Ash agreed well with those obtained by other methods. Isotopic analysis of Ni and its application to accurate and precise determination of Ni by stable isotope dilution method were performed.

RAPID DETERMINATION OF SPECIFIC ACTIVITY OF NICKEL-63

For the determination of specific activity of63Ni, a method has been developed for simultaneous assessment of both stable and radionickel. The method comprises solvent extraction of Ni-dimethylglyoxime into xylene for spectroscopic measurement and liquid scintillation counting of the extractant. The application of the method has been successful for63Ni in the corrosion products accumulated on the wall surface in the primary circuiting tube of the reactor.

Multi-element analysis of environmental samples by cold and thermal guided neutron induced prompt gamma-ray measurement

Non-destructive multi-element determination in environmental samples by neutron-induced prompt γ-ray analysis (PGA) has been investigated. Comparative standardization for the elements including H, B, C, N, Na, Mg, Al, Si, P, S, Cl, K, Ca, Ti, Mn, Fe, Co, Cd, Sm, Gd, Hg by PGA has been carried out using the cold and thermal guided neutron beams of JRR-3M reactor and then several environmental reference materials have been analyzed. Accuracy and precision of better than 20% were found for these elemental analyses except for H, C, N and Cl in biological samples. Detection limits in various environmental matrices were 25 to 820 ng/g for B, Cd, Sm and Gd, 1.1 to 820 μg/g for H, Na, S, Cl, K, Ti, Mn, Co and Hg, and 0.031 to 10% for C, N, Mg, Al, Si, P, Ca and Fe. The present method is being applied to environmental studies of post war Persian Gulf together with INAA and ICP-MS.

The precipitation of some actinide element complex ions by using hexammine cobalt(III) cation—I: The precipitation of thorium and plutonium(IV) carbonate complex ions with hexammine cobalt(III) chloride

Abstract The precipitation behavior of thorium, neptunium(V), plutonium(IV) and americium(III) in ammonium carbonate solution with hexammine cobalt(III) chloride was studied. Orange and green-yellow precipitates were produced in the case of thorium and plutonium(IV), respectively, while no precipitate of americium(III) was observed under the same conditions. On the other hand, neptunium(V) was precipitated as a white compound in ammonium carbonate solution before hexammine cobalt(III) chloride was added. The composition of the thorium and plutonium(IV) compounds were dihexammine cobalt(III) thorium pentacarbonate aquo trihydrate, [Co(NH3)6]2[Th(CO3)5·H2O]·3H2O, and dihexammine cobalt(III) plutonium(IV) pentacarbonate aquo tetrahydrate, [Co(NH3)6]2[Pu(CO3)5·H2O.]·4H2O. Chemical and crystallographic properties of the two compounds and crystallographic property of the uranium(VI) compound were also studied.

The precipitation of some actinide element complex ions by using hexammine cobalt(III) cation — II: The precipitation of thorium, uranium(VI) and plutonium(IV), (VI) sulfate complex ions with hexammine cobalt(III) cation

Abstract The precipitation behavior of thorium, uranium(VI), neptunium(V), plutonium(IV), (VI) and americium(III) in an ammonium sulfate solution with hexammine cobalt(III) ion was studied. Orange colored precipitates were produced in the case of thorium, uranium(VI) and plutonium(VI), and green yellow colored precipitate was produced in the case of plutonium(IV), respectively. On the other hand, no precipitate of neptunium(V) and americium(III) was observed under the same conditions. The compositions of the thorium, uranium(VI) and plutonium(IV) compounds were, respectively, di[hexammine cobalt(III)][thorium pentasulfate] dihydrate, [Co(NH 3 ) 6 ] 2 [Th(SO 4 ) 5 ]·2H 2 O, di{[hexammine cobalt(III)]bisulfate} [uranium(VI) dioxo trisulfate] pentahydrate, {[Co(NH 3 ) 6 ]·HSO 4 } 2 [UO 2 (SO 4 ) 3 ]·5H 2 O, and di[hexammine cobalt(III)][plutonium(IV) pentasulfate]trihydrate, [Co(NH 3 ) 6 ] 2 [Pu(SO 4 ) 5 ]3H 2 O. Chemical and crystallographic properties of the three compounds and crystallographic property of the plutonium(VI) compound were also studied.

The precipitation of some actinide element complex ions by using hexammine cobalt(III) cation—III The precipitation of neptunium(VI) and americium(VI) sulfate complex ions with hexammine cobalt(III) cation

Abstract The crystalline compounds {[Co(NH3)6]HSO4}2[NpO2(SO4)3]. nH2O and {[Co(NH3)6] HSO4}2[AmO2(SO4)3] · nH2O were prepared by addition of hexammine cobalt(III) ion to an aqueous solution of M O22+. They are isostructural with {[Co(NH3)6]HSO4}2[UO2(SO4)3]·5H2O: c symmetry of the diamond type, with lattice constant a = 10·74 A for both neptunium and americium compounds. Absorption spectra for neptunium(VI), plutonium(VI) and americium(VI) compounds in dilute sodium carbonate solution are also presented.

Measurement of30Si as a tracer by neutron-induced prompt gamma-ray analysis

The application of stable isotope analysis using neutron-induced prompt γ-ray analysis (PGA) with cold/thermal neutron beams for the tracer study of geological materials are discussed. Silicon has three natural isotopes differing in abundance:28Si (92.23%),29Si (4.67%) and30Si (3.10%). For the purpose of the assessment of Si migration in engineered barrier material, enriched30Si can be used as a tracer due to its nuclear and chemical properties. Isotope analysis of30Si was performed by PGA during the tracer study. Neutron intensity at the sample position was 1.4·108 n¢cm−2·s−1, 2.4·107 n·cm−2·s−1 for cold and themal neutron guided beams of JRR-3M, respectively. Calibration curves and analytical sensitivity of30Si were determined based on measurement of standard samples. BG and detection limits for30Si analysis were also measured in Japanese bentonite (Kunigel V1 and Kunipia F) and their pore water. Fiffteen elements were determined simultaneously using PGA.

Application of Neutron-Induced Prompt Gamma-Ray Analysis for Determination of B-10 in BNCT

Twenty-six brain tumor patients have been treated with the boron neutron capture therapy (BNCT) at the JRR-2, Japan Atomic Energy Research Institute (JAERI)1, since 1990. An accurate analysis of ppm levels of 10B content in tissues is essential for determining neutron irradiation dose in the BNCT. Although the ppm level of 10B can be analyzed by destructive analytical methods of inductively coupled plasma atomic emission spectrometry (ICP-AES) and spectrophotometry, due to the necessity of sample decomposition, these methods are not suitable when quick analysis is required for determining the neutron irradiation dose before the BNCT treatment. A neutron-induced prompt γ-ray analysis (PGA)2 is characterized by the capability of nondestructive 10B analysis. On account of large cross section of the reaction 10B(n,α)7*Li (σ = 3837 barn), the Doppler broadened 478 keV photo-peak is observed with the highest sensitivity by the PGA. The 10B in the tissues was determined by measuring the 478 keV peak area against the 2223 keV peak area for the 1H as an internal standard3,4.

Determination of Boron in Animal Materials by Reactor Neutron Induced Prompt Gamma-Ray Analysis

Boron concentration of plasma, feces, urine and body tissues from sheep fed with borated water (100 mg B/l) and tap water were determined by neutron-induced prompt gamma-ray analysis to elucidate boron metabolism. The B level in plasma and urine increased rapidly and the B content of feces increased greatly. The B concentrations in body tissues (liver, kidney, spleen, thyroid and muscle) of B dosed sheep were ten times higher than those of tap water administered sheep.