The molecular state of epoxy resins for cryogenic use has been studied in terms of positron lifetime measurement. The addition of plasticizer increased the free volume in the epoxy and hence the ductility of the epoxy at room temperature was increased. The fracture toughness at cryogenic temperatures, however, decreased. The increase of molecular weight between crosslinks decreased the free volume in the epoxy at room temperature and increased the fracture toughness slightly at cryogenic temperature. Based on the data the molecular state model desired for cryogenic application was proposed and the nano-sized silica dispersed epoxy was prepared by means of sol-gel method to follow the model. The cryogenic properties of the silica dispersed epoxy and the free volume evaluated by positron annihilation lifetime were also discussed.

Labelling of DTPA bicyclic anhydride coupled antibodies were investigated by determining the effect of DTPA: antibodies, DTPA: Sn molar ratios, pH, dimer and polymer formation of antibodies coupled with DTPA, using three different radionuclides, [¹¹¹In,⁹⁰Y and^99mTc]. Analyses were performed with by Whatman No. 1 paper strips. Under optimal conditions we have achieved specific activities of¹¹¹In or⁹⁰Y labelled antibodies of about 37 kBq/1 μg for IgG coupled with about 2 DTPA groups per molecule and protein concentration of 15 mg/ml.

Radiometric correction and interpolation methods have been worked out for rhenium determination with extraction of the tetraphenylphosphonium complex into dichloroethane. Liquid scintillation counting was used. The method allows to determine from 1 to 100 μg of rhenium(VII) in analyzed probe. The relative standard deviation is 0.05–0.09 over the whole concentration range.

An analytical procedure for rapidly screening large numbers of oils for polychlorinated biphenyl (PCB) content has been developed and is now in routine use. Pontential levels of PCBs are inferred from chlorine concentrations as determined using the automated neutron activation analysis (NAA) facility at the Los Alamos National Laboratory Omega West Reactor. The technique is designed to screen up to 200 oil samples per eight hour working day, using a sample volume of approximately 1 milliliter. Because of the automated nature of the analysis, elements in addition to chlorine are determined, when present. These include fluorine, bromine, iodine and sulfur. U.S. National Bureau of Standards (NBS) and U. S. Environmental Protection Agency (EPA) Standard Reference Materials are routinely analyzed for quality assurance purposes. The results of our analyses of these materials for certified elements is discussed as well as results for other non-certified elements observed in the standard materials.

Gamma radiolysis of 2-acetylfuran (AF) in 2-propanol, in absence of atmospheric oxygen, has been investigated. The radiation yields of hydrogen, methane at different doses as well as radiolytic products in solution were determined. The radiolytic products were determined by gas chromatography coupled with mass spectrometry. The mechanisms for formation of detected radiolytic products and the effect of (AF) concentration on hydrogen and methane yields are discussed.

Using the positron annihilation lifetime technique, the annihilation parameters have been measured for epoxy and high density polyethylene (HDPE) as a function of AC electric field strength and the exposure time. The lifetime spectra have been resolved into three components, the longest component (I₃τ₃) is attributed to the pick-off annihilation of o-Ps in the amorphous regions. The intermediate one (I₂τ₂) is due to the annihilation of free positrons, while the shorter component (I₁τ₁) stems from self annihilation of p-Ps. In HDPE, the o-Ps parameters τ₃ andI₃ are measured as a function of electric field strengths in the range from 10 to 100 kV/cm exposed for 24 hours. A decrease inI₃ of ∼8% is observed from zero to 50 kV/cm followed by an increase of the same order from 50 to 100 kV/cm. By investigating the effect of the exposure time from 2 to 24 hours at 16 and 50 kV/cm, the effect is confirmed and is attributed to the inhibition of o-Ps formation at lower field strength. In epoxy, the effect or exposure time onI₃ at 166 and 133 kV/cm shows a similar behavior as in HDPE. At 133 kV/cmI₃ decreases by only 2.5%. On the other hand, the changes in τ₃ occur at short exposure times. Again at large times the saturation is obtained. These effects are attributed to the expansion of free volume (increase of τ₃) competing at longer exposure times with other phenomena, such as liberation of free radicals, which reduce the o-Ps intensityI₃ through the conversion to p-Ps. The reactions between o-Ps and free radicals might also lead to free positrons, which could explain the increase ofI₂ and the decrease of τ₃ at longer exposure times.

The multitracer technique was applied to elucidate of influence of humate formation on adsorption behavior of ultratrace elements. Dissolved fractions of Co, As, Rb, Sr, Y, Zr, Ba, Ce, Eu, Gd, Tb, Yb, Lu, Hf, Re and Pt in contact with kaolinite or silica gel were determined simultaneously either in the presence or absence of humic acid, which was partly adsorbed on the solid. Percentage of dissolved fraction of rare earth elements was identical to that of humic acid, indicating high stability of the rare earth-humate complex. Hydrolysis was the most important factor controlling the behavior of Zr and Hf. Both hydrolysis and humate complexation influenced the adsorption of Co, Sr, Ba and Pt, whereas neither affected the distribution of As, Rb and Re.

This paper describes an automated fuel element scanning system, based upon gamma-ray spectroscopy, that has been developed at the Oak Ridge Research Reactor. The scanning system is located in the reactor pool and allows fuel elements to be scanned nondestructively at various intervals during their core life. Fuel elements are located 430 cm beneath the pool. Gamma-ray measurements (aided by a collimating assembly) are made using a GeLi detector positioned above the pool water. Measurements of¹³⁷Cs count rates from relatively “cold” elements indicate that the counting data obtained using this apparatus is reproducible within 5%. Power distribution in the reactor's core (element by element) has been derived from¹⁴⁰La counting data. The method of determining power is discussed briefly and some example results are presented.

The gamma radiolysis of malonic acid, succinic acid and their corresponding nitriles was carried out over a wide interval of radiation doses. The radiolytic products detected were H₂, CO₂, CO, NH₃ and carboxylic acids. The results obtained supported the hypothesis that in the prebiotic milieu, ionizing radiation might have contributed to the synthesis of compounds of relevance in biological systems.

Thorium was quantitatively extracted from 0.04M picric acid with 0.065M of 18-crown-6 at pH 2.0–3.5. It was stripped from organic phase with 0.5M nitric acid and was determined spectrophotometrically at 655 nm as its Arsenazo-III complex. Thorium was separated from mixture containing cerium, uranium, zirconium, hafnium, yttrium and lead in complex mixtures. The method was extended for the analysis of thorium in monazite.

The interaction between the halogen atom and the aromatic substrate, responsible for the deviation from the Reactivity-Selectivity Principle in homolytic aromatic halogenation in the high energy region (hot homolytic aromatic halogenation) is discussed.

A total of 40 crude oils from 10 different oil fields in Nigeria were analysed for 39 elements by Instrumental Neutron Activation Analysis (INAA). Significant correlations were found between Ni and V concentrations and Ni versus Se concentrations. The American Petroleum Institute (API) gravities are inversely correlated with total transition metal concentration of the oils but there is no obvious correlation of the V/Ni ratio with the age of the oil fields. The oils are very similar to North Alaska Type B oils in key transition metal parameters and cluster analysis results using the transition metals as variables indicate that the oils might have been formed from two closely related sources.

Relation between available phosphorus in 6 types of paddy soil in, Human Province and its uptake by rices was studied by³²P tracing. The result indicated that the P uptake by rices varied with available P content in the paddy soils. When the content was high, the rice absorbed more P nutrient from the soil and decreased the P uptake from the P fertilizer, which showed a poor contribution of the P fertilizer to the rice yield increase, and vice versa. The recovery of the P fertilizer varied with the soil types. Ranked the first was in paddy soils derived from lacustrine deposite but little rice yield increased. While in paddy soils derived from limestone, the yield greatly increased although the recovery of P fertilizer was the lowest. Rice absorbed P nutrient during its whole growth duration. No matter the different uptake amount due to the P supply by the different soils, rice plant generally had the greatest P nutrient uptake from tillering stage to elongation stage, and along with the rise of the rices dry matter, amount of P uptake was gradually increased but the P content in unit dry matter was tended to decrease.

A gamma-spectrometric method has been developed for the determination of radioactivity of phosphate rocks, products and residues of technologies. After discussing an introduction of the phosphate processing technology, the experimental results concerning U, Th and their daughter elements and⁴⁰K are presented. Furthermore, the results of investigations on the assay of radon are summarized.

Instrumental epithermal neutron activation analysis in conjunction with Compton suppression methods has been used to determine cadmium concentrations in seven biological reference materials. The¹¹⁴Cd(n, γ)¹¹⁵CD(t_1/2=53.3h→^115mIn(t_1/2=4.5h) reaction using the 336.3 keV photopeak was successfully employed to achieve an overall precision between 4%–15% and detection limits between 10–20 ng/g. The accuracy of the results as compared to the certified or compilation values was in excellent agreement.

The extraction of Pa(V) from 1M perchloric acid medium with HDEHP in toluene was carried out. The different factors affecting the metal distribution coefficient such as HDEHP concentration in the organic phase, pH of the aqueous phase and the equilibrium temperature were followed. From the data obtained the equilibrium constants of the extraction reaction were calculated. From the temperature variation, the corresponding thermodynamic parameters (ΔG, ΔH and ΔS) were also derived. In the same way, the effect of addition of some N-and 0-containing solvents such as pyridine, 2,2′-dipyridyl, n-amyl alcohol, n-decyl alcohol and n-butyl acetate, to the HDEHP organic phase was demonstrated. From the data obtained the suggested mechanisms for the synergistic extraction reactions were discussed together with the corresponding values of the thermodynamic parameters.

Methods for the preparation and analysis of a new renal radiopharmaceutical,^99mTc-thiodiglycolic acid (TDGA), are reported. The kit for Tc-TDGA contains a lypophilized acidic (pH 2.5) mixture of 5 mg TDGA and 0.05 mg SnCl₂·2H₂O. Acetate buffer has been found to be a suitable solvent for paper chromatography of^99mTc-TDGA. The results of the quantitative organ distribution studies in rats and rabbits indicated the characteristics of^99mTc-TDGA to be intermediate to the renal tubular agent¹³¹I-Hippuran and the GFR agent^99mTc-DTPA.

The charged particle activation analysis of ultra-trace carbon in boron-doped silicon with the¹²C(d,n)¹³N reaction has been developed. In order to apply¹³N substoichiometric separation to determine carbon in silicon, we studied the rapid dissolution of silicon using nitric acid as the¹³N carrier. Its amounts were as small and definite as possible and the nitrogen oxide gas produced during the dissolution was collected. Silicon was dissolved for 6 min in a mixture of hydrofluoric acid, acetic acid and phosphoric acid, which contained potassium nitrate as the¹³N carrier and nitrogen oxide was collected in the sodium hydroxide solution. In order to combine the dissolution method with¹³N substoichiometric separation, the conditions for steam distillation as pre-separation were also refined in relation to increases in the amount of carrier. Nitrogen-13 was separated substoichiometrically after silicon dissolution and steam distillation. This analytical procedure was used to determine carbon in boron-doped CZ−Si. Carbon at 0.7–12.7·10¹⁵ atoms/cm³ was determined with good reproducibility. It took less than 30 min to start the radioactivity measurement after the end of iradiation. The detection limit was 2·10¹³ atoms/cm³ (0.2 ppb).

Lichen (species Trypethelium Eluteriae) is analysed for different elements. Nondestructive instrumental neutron activation analysis is employed for the multielemental analysis. Gamma-ray spectrometry is used for the identification and quantitative estimation of elements. Concentrations of 24 elements are reported. Gamma-ray spectrum of the lichen irradiated for 16 hours, delayed for 10 days, and counted for 10 hours on a 50 cm³ coaxial Ge(Li) detector is given.

A set of interactive routines has been developed to use a personal computer for instrumental neutron activation analysis. The program operates a multichannel analyzer by remote control and output concentrations, standard deviation and/or detection limit for each requested element. The program is able to combine data from several spectra, so that computation is continuous and takes less than 4 minutes for 15 elements. Reliable results have been obtained for low peak/background ratios encountered in atmospheric and marine particulate matter analyses.

Extraction of actinides has been examined in two-phase aqueous systems based on poly(ethylene glycol) (PEG) from sulfate solutions in the presence of potassium phosphotungstate, which forms strong complexes with ions of tri- and tetravalent transuranium elements. Extraction of these complexes by aqueous PEG solution is complete in contrast to that of penta- and hexavalent actinides. Conditions have been chosen for the separation of actinides in different oxidation states.

An accurate and precise wavelength dispersive X-ray fluorescence spectrometric method is described for the quantitative analysis of hafnium impurities in zirconium oxide matrix in the range from 6.8 to 1004 μg/g, using the HfL_β1 line on 8420⁺ XRF Quantometer (ARL) with LiF (220) crystal and scintillation detector. The practical limit of measurement is 6.8 μg/g. The precision is between 1 to 6% for higher and lower concentrations of hafnium, whereas accuracy in most cases is <5%.

In experiments performed to simulate the interaction of cosmic radiation with matter, a great variety of high purity elemental foils and simple compounds were exposed to energetic charged and uncharged particles. In order to determine production rates of long-lived radionuclidesi such as¹⁰Be (1.6 My),²²Na (2.602 y),²⁶Al (0.72 My),⁴¹Ca (0.1 My),⁴⁴Ti (47.3 y),⁵³Mn (3.8 My), and⁵⁹Ni (0.07 My), by means of γ-spectroscopy, γ-γ-coincidence measurements, neutron activation techniques, as well as the recently developed method of accelerator mass spectrometry, radiochemical separations with high decontamination factors were carried out, lowering isotopic ratios of interfering short-lived radioisotopes and stable isobars to levels of up to 10⁻¹³. The separation methods applied include ion exchange, solvent extraction and the use of selective ion retention media as well as classical precipitation methods.

A method for the simultaneous, radiochemical neutron activation analysis of uranium and thorium at trace levels in biological materials is described, based on a technique known as LICSIR, in which a double neutron irradiation is employed. In the first, long irradiation²³³Pa (27.0 d) is induced by neutron capture on²³²Th and then the sample is cooled for several weeks. A second short irradiation to induce²³⁹U (23.5 m) is followed by a rapid sequential radiochemical separation by solvent extraction of²³⁹U with TBP and²³³Pa with TOPO. Chemical yields of²³⁹U and²³³Pa were measured for each sample aliquot using added²³⁵U and²³¹Pa tracers from the γ-spectra of the separated fractions. The technique was validated by quality control analyses.

Leaching of micro-constituents from a granular silicate can be described by a specific mass transfer function. This quantity may be determined for column leaching experiments by radioanalysis of the eluate for about 15 elements. Concurrently, the internal diffusion and the isotopically exchangeable mass of the various micro-components may be determined by radiotracer experiments. This text summarizes the quantitative formulation of the leaching process and the use of radiotracers in it.

The present manuscript reviews the use of amines (primary, secondary and tertiary chains and quaternary ammonium salts) as extracting agents for the quantitative determination of actinides in biological samples. Among the primary amines, only Primene, JM-T is used to determine Pu in urine and bone. No one has investigated the possibility of using secondary amines to quantitatively extract actinides from biological samples. Among the tertiary amines, tri-n-octylamine, tri-iso-octylamine, tricaprylamine (Alamine) and trilaurylamine (tridodecylamine) are used extensively to extract and separate the actinides from biological samples. Only one quanternary ammonium salt, methyltricapryl ammonium chloride (Aliquat-336), is used to extract Pu from biological samples.

A method for Cr determination in biological samples based on proton nuclear activation is presented. The activation was induced by a 13.8 MeV proton beam of the AVF Cyclotron of Milan University via a (p, n) reaction on the nuclei of the target. For the quantitative determination Cd has been chosen as reference element. The method has been applied to Cr determination in human serum samples. The experimental procedure is described and results are presented and discussed.

Stability and distribution constants of thallium(I) chelates with dimethyl-, diethyl-, di-(n-propyl)-, di-(n-propyl)-, di-(i-propyl)-, di-(n-butyl)-, di-(i-butyl)-, di-(sec-butyl)- and di-(i-amyl)-dithiophosphoric acids have been radiometrically determined using ion-exchange and extraction methods. The length of the alkyl chain influences considerably the distribution constant, however, it has only a small effect on the stability constant.

A modified⁹⁹Mo−^99mTc gel generator is described. The present generator uses an insoluble zirconium molybdophosphate (ZrMP) gel tagged with⁹⁹Mo. Molybdenum-99 is chemically combined in the gel structure and cannot be eluted from the matrix. The presence of phosphate increases the chemical stability of the gel and decreases the molybdenum breakthrough. The prepared gel is sufficiently porous to permit ready diffusion of^99mTcO ₄⁻ which can be cluted with saline in yields of up to 90%. The gel was found to contain 25.1% Mo, 21.9% Zr, and 0.7% P in a molar ratio of 1.09:1.0:0.09, respectively. The high molybdenum content of the gel allows the use of cheap, non-polluting (n, γ)⁹⁹Mo. The eluted^99mTc was of high purity and can be used for medical and pharmaceutical applications.

This work briefly describes the basic principle of Elastic Recoil Detection Analysis. From a theoretical analysis of the physical process, we discuss the choice of the best experimental configuration for solid surface examination and particularly the advantages of the transmission geometry. Then, we propose a new calculation procedure for the collision cross section¹H(⁴He,⁴He)¹ H between 0.5 and 8 MeV helium ions energy, and finally we analyze in more detail the cross section results in the low energy range (1 to 2.5 MeV).

The paper describes a destructive neutron activation procedure for the determination of all platinum group elements (PGE). Only a few steps are required after irradiation, namely sample dissolution, osmium and ruthenium separation by solvent extraction, anion exchange separation of remaining noble metals and counting. The chemical yield is evaluated. The method has been used for the determination of noble metals in a large variety of standard reference materials, mainly of geological and technological origin. The results, given as the average of four independent analyses are reported and discussed. Average precision for the whole procedure is usually below 8% and sensitivities are adequate to meet the analysis requirements of terrestrial PGE- and Au-poor materials.

Distributions of some elements (Cr, Fe, Co, Sb, Sc and Zn) in normal and pathologically altered human colon mucosa tissues have been investigated by INAA. The following tissues were analyzed: normal colon mucosa, colitis chronica, colitis ulcerosa, adenoma tubulare and adenocarcinoma (Diagnoses were previously confirmed clinically and histopathologically).

The values of contents of elements in these tissues (C_x in nkg/g) are treated by specific computer funcional programs. The following was found: regression functions of these parameters for the altered tissues in comparison to the normal, and specific functional correlations of the C_x/C_y relations for pairs of investigated elements. We have also determined the functions which characterize these relations for the investigated colon mucosa tissues.

The knowledge of quantities of alpha-active nuclides (especially Pu and Am) present in contaminated metal waste from decommissioned nuclear power plant, is very important for treatment of this metal waste by melting technology. The surface part of the analyzed metal was mechanically or electrochemically removed until bulk material was reached. The iron was removed in the form of an amalgam. Pu was separated from Am by extraction with TTA and the main contaminants of the metal surface were determined after counting previously electrodeposited samples.

The ESR method was used to study the regularities of formation of silver atoms in gamma-irradiated aluminium silicate modified by yttrium and containing¹⁰⁹Ag istope ions introduced by various techniques. The existence of two types of silver atoms and an Ag ₂¹ complex stabilized an the surface of a gamma-irradiated carrier has been established. g-Factors and superfine structure constants of spectral lines of paramagnetic silver particles belonging to various types observed on the surface have been calculated. Quantitative correlations of paramagnetic silver particles and the nature of their kinetic dependences in a broad temperature range (from 77 to 353 K) are determined by the number of silver ions introduced into the carrier and by the mode of introduction, thermal and vacuum pretreatment of the samples, irradiation dose and the temperature of investigating the gamma-irradiated surface.

Continuing comparative analyses of clinoptilolites from various deposits in the USSR and Bulgaria carried out with the aim of selecting best samples and acquiring data going into computation and optimization of the process of APS liquid sewage decomtamination, we have studied the kinetics of strontium sorption on clinoptilolites from Dzegvi and Tedzami (USSR), Bely Plast and Bely Bair (Bulgaria) varying in function of the initial cationic form (Na, NH₄, natural), graining and other parameters. It is shown in the paper that strontium sorption on various cationic forms of clinoptilolites from Dzegvi, Tedzami and Bely Plast is rigorously governed by the laws of diffusion kinetics, while in the case of Bely Bair clinoptilolites it has some peculiar features. Attempts have been made to explain these differences. Descriptive of all clinoptilolites (except Bely Plast clinoptilolite) is the fact that the velocity of exchange on a sodium form is higher than that on an ammonium form, this latter being comparable with the natural one. The first stage of exchange (up to 8 h) reveals dependence on graining. Inferred from the experimental data are coefficients of diffusion at the first, most rapidly developing stage of exchange.

A method for the determination of erbium by instrumental neutron activation analysis in rocks using 2.28 s^167mEr has been developed. The technique employs pseudocyclic activation in an epithermal neutron flux and a detection limit of 0.5 μg/g was attained. Eight international rock standards were analysed to test the method.

Various theoretical and practical aspects of epithermal neutron activation analysis (ENAA) and fast-neutron-induced reaction interferences in conventional instrumental thermal neutron activation analysis (TNAA) have been considered. A new generalized advantage factor which reflects a practical improvement of detection limits in ENAA is proposed. In the determination of practical advantage factors, consideration is also given to the different irradiation channels available for the experiment in a given reactor, or even in several accessible reactors. Fast neutron reaction interference factors are tabulated for both ENAA and TNAA and examples are given of specific interferences in TNAA for some biological and geological matrices.

The analytical procedure includes irradiation by 30 MeV photons followed by a chemical separation by evolution from molten KOH. Two radiochemical states of nitrogen are observed: NH₃ and N₂. Finally all nitrogen is converted to N₂, which is absorbed on titanium sponge. Carbon is converted to CO₂, which is absorbed in a KOH solution. This procedure was applied to silicon samples of various purity. Detection limits of 0.01 μg carbon and 0.1 μg nitrogen were achieved.

Damage initiated by halogen recoil atoms in mixed hexabromochlorometallates has been evaluated with the help of the impact-induced multiple Ligand Abstraction (IMULA) model. The essential reactions within the scope of the model are (1) primary retention for recoil atoms with energies below some threshold of displacement energy, (2) halide-halide substitution reactions (billiard ball reactions), (3) reactions in which two or more halide ligands are displaced with subsequent reoccupation of the vacancies by adjacent halides and (4) formation of interstitials which form free halide during the dissolution of the irradiated substances. It was found that for all recoil atoms and both potassium hexabromochlorometallates the contributions of the different reaction channels are very similar: (1) 4–18% (2) 40–50%, (3) 25–30% and (4) 12–20% These results do not differ essentially from results so far obtained in mixed crystal systems.

Recommended k₀-factors and related nuclear data for use in (n, γ) activation analysis are given for 72 isotopes. In addition the basic nuclear constants and experimental parameters needed in the k₀ standardization method are reviewed. For convenient data reduction, computer programs were developed.

The influence of matrix physical state on the^95mTc decay in M₂^99(95m)TcX₆ has been studied. In the solid, the^95gTc retention was constant (83%) independently of the matrix amount up to a limiting value of the^95mTcF ₆²⁻ /K₂⁹⁹TcF₆ ratio. Then the decrease of matrix amount led to a decrease of the^95gTc retention to 34%. This value remained constant upon further decrease of the matrix. In frozen solutions, the^95gTc retention was found to be 18–20% independently of the type of compounds and their concentrations up to 10⁻² M. In the same range of salt concentrations, the retention in solution was found to be 3%. The increase of salt concentration to 2·10⁻² M led to an increase of retention in frozen solutions but did not affect its value in solution.

The sediment samples have been collected from estuarine regions of Mindola and Purna of Gujarat State. These samples are found to contain less than 3% of organic matter which scavange and carry most of the activity of²²⁶Ra, etc., to the sediment floor. The activities of²²⁶Ra are found to vary from 0.1 to 0.5 pCi/g, while²¹⁰Pb activities lie in the range of 3 to 8 pCi/g. These activities find their way into the organisms present in sea water and then into fish which is finally consumed by humans. This paper gives in detail the sampling techniques, experimental procedures and the distribution of the isotopes of²²⁶Ra and²¹⁰Pb in the estuarine regions and the concentration factors of²²⁶Ra in the region.

Extraction of perchloric acid by the nitrobenzene solution of Slovafol 909 (p-nonylphenylnonaethylene glycol, L) has been investigated and the composition of species in the organic phase has been determined. It has been found, that perchloric acid is full dissociated in both phase, and H⁺ ion in the organic phase is partially solvated by one or two molecules ofp-nonylphenylnonaethylene glycol. Extraction and stability constants of HL⁺ and HL ₂⁺ species in the organic phase has been evaluated.

The extraction of uranium(VI) from an aqueous HNO₃ phase into an organic phase consisting of a polyurethane foam immobilizing a solution of di(2-ethylhexyl)phosphoric acid (HDEHP) in o-dichlorobenzene has been investigated at varying concentrations of nitric acid and HDEHP. The mechanism of the extraction is discussed on the basis of the results obtained. The aggregation number of HDEHP immobilized on the foam was obtained from the analysis of data obtained for the extraction of cerium(III) from acidic perchlorate solutions of constant ionic strength.

Helium-3 (³He) mass spectrometry for the analysis of low-level tritium (³H) concentrations (0.5 to 5 Bq·l⁻¹) in environmental sample matrices was compared with conventional low-level β-decay counting methods. The mass-spectrometry method compared favorably, equalling or surpassing conventional decay-counting methods with respect to most criteria. Additional research and method refinements may make³He mass spectrometry the method of choice for routine, low-level to very-low-level (L<0.5 Bq·l⁻¹)³H measurements in a wide variety of environmental samples in the future.

The accuracy of dual energy X-ray absorptiometry (DEXA) for measurement of bone mass carried out by quantitative digital radiography (Hologic Inc.) was compared to results with neutron activation analysis (NAA) on 106 subjects. The accuracy with DEXA was further investigated by measurements on aluminium samples of known composition. DEXA measured 4 lumbar vertebrae by spine scan. The central third of the skeleton also was measured by whole body scan to obtain data on the same large part of the skeleton as measured by NAA. Results suggested that DEXA spine scans were more reliable than whole body scans. In addition, the measurement of total mineral content (BMC) was more reliable than the normalization of BMC to bone surface area (BMC/Area) or bone mineral density (BDM). Since the proportion of bone below detection would increase with development of osteoporosis, with osteoporosis the BMC would be increasingly underestimated, but to only a small extent, while the BMD would be more significantly overestimated.

Monitoring of personnel working with enriched uranium implies development of techniques for excreta analysis, mainly for urine, with very low detection limits.

The method described allows the determination of enriched uranium after extraction in tri-n-octylphosphine oxide (TOPO), 0.5M in toluene, supported on polypropylene capillary columns¹. Alpha activity is later measured in a low background liquid scintillation equipment² and a fluorimetric determination is performed³ with detection limits for 800 ml of urine of 12±4 mBq/l and 0.08±0.01 ug/l.

Planetary gamma-ray spectroscopy can be used to chemically analyze the top soil from planets in future planetary missions. The production from inelastic neutron interaction plays an effective role in the determination on the C and H at the surface. The gamma-ray production cross section from the strongest lines excited in the neutron bombardment of Fe have been measured by the use of a time analyzed quasi-mono-energetic neutron beam and a high purity germanium detector. The results from En=6.5, 32, 43, and 65 MeV are presented.

A radiochemical procedure was developed and optimized which allows sensitive²⁴¹Pu measurement in various sample materials. As a first step, Pu isotopes are separated from matrix elements, purified radiochemically, electroplated, and measured by α-spectrometry. The electrodeposited Pu is then redissolved in nitric acid and extracted with trioctylphosphinic oxide/cyclohexane. The organic phase is mixed with scintillator cocktail (PPO/Xylene) and Pu is measured with a liquid scintillation counter. The detection limit of the optimized procedure for a counting time of 100 minutes is 50 mBq²⁴¹Pu per sample at a 95% confidence level.

The concentrations of trace elements As, Br, Cd, Cr, Cu, Hg, Pb, Sb, Se and Zn in Chinese foodstuffs were determined by instrumental or radiochemical neutron activation analysis or atomic absorption spectrometric methods. 1198 samples including 20–25 kinds of main foodstuffs were analyzed. The results are given and the daily intake of the trace elements for population groups concerned have been calculated.

A method of determination of elemental contents in compound substances has been elaborated. The method is based on the simulation of the energy spectra of elastically scattered ions and recoil nuclei. The simulated spectra are then compared with the measured ones. Effects influencing the spectra, such as bombarding beam energy spread, the energy straggling of ions and the finite resolution of the spectrometer, are accounted for in the algorithm.

The synergic extraction of La(III), Eu(III), and Lu(III) with 2-thenoyltrifluoroacetone (Htta) and triphenylarsine oxide (tpao) in benzene has been studied. The extractability of lanthanoids, Ln(III), is significantly affected by the association of Htta with tpao in the organic phase. The associated species is Htta·tpao and the association constant is determined as 10^1.63. The intrinsic extraction equilibrium of Ln(III) is analyzed using the free concentration of Htta and tpao. The synergic enhancement is ascribable to the formation of the adduct complexes shown as Ln(tta)₃tpao and Ln(tta)₃(tpao)₂ in the present extraction system. The adduct formation constants determined are very large as expected from the high basicity of tpao.

The presence of excess uranium-235 was detected in many of the rain samples collected at Fayetteville (36°N, 94°W), Arkansas, during the period between April 1983 and March 1984. The experimental data indicate that the uranium-235 originated from the nuclear reactor on board the Soviet satellite Cosmos-1402, which fell over the South Atlantic Ocean on 7 February 1983.

A new picosecond pulse radiolysis “Twin LINAC System” has been constructed recently at Nuclear Engineering Research Laboratory at the University of Tokyo. The time resolution of the system is 20 ps and the system has a versatile capability for pulse radiolysis study. The outline of the facility is introduced. Some research carried out using the facility is presented. The examples are radiolysis of CCl₄ and n-C₂₁H₄₄.

This work is part of a project with the IAEA, in a coordinated program on “Trace Elements in Human and Bio-Environmental Systems” to evaluate their nutritional requirements, interrelations and the role of trace elements in health, metabolism, etc. Cow's milk being regarded as one of the most important and nutritious foodstuffs consumed by people. Hence as a first step, an elemental analysis for milk was carried out for this purpose; a few samples of pasteurized milk and local sample were investigated for essential and toxic trace elements. The secondary aim of this project was the assessment of various analytical techniques involved. However, in the present work, the methods involved were AAS, PIXE and NAA. The latter method was applied both instrumentally and radiochemically. Although the results pertaining to the various methods employed are not in good agreement. there is, however, some justification to clarify this internal inconsistency. The precision of NAA and AAS allows a greater degree of acceptance. Although PIXE is very fast and rather routine, the technique for trace element analysis needs certain adaptations and development.

A preliminary result employing neutron activation tomography in the study of the diffusion of a preservative in a sample of Scots pine is presented. The ability to determine the spatial distribution of elements within the wood without recourse to destructive sectioning makes this a better technique than others currently available.

Adsorption of radioactive gases and vapours is surveyed. Rare gases, iodine and its compounds, tritium and its compounds, carbon in the form of carbon dioxide, and ruthenium in the form of ruthenium tetroxide can be rated among these radioactive gases. Absorbents used for the removal of gaseous radionuclides (activated carbon, molecular sieves, silica gel, oxides, etc.) are surveyed, the adsorption mechanism is discussed and the effects on adsorption of various gas and adsorbent parameters are summarized. Qualitative description of the dynamic adsorption in the adsorption column is presented.

The excretion of inhaled poorly transportable compounds of uranium relative to chest content has been measured in humans by a substantial number of measurements of urine, feces, andin vivo measurements over the chest. The use of these measurements have permitted us to compare the results predicted by the models with empirical observations in humans. The ICRP-30 model for inhaled class Y compounds of uranium along with the ICRP-30 systemic model, no matter what the particle size, grossly underpredicts urinary excretion over time than that observed in human occupationally exposed to poorly transportable compounds of uranium by inhalation. Conversely, if urinary excretion were to be used to estimate the contents of poorly transportable uranium compounds in the lung using ICRP-30 models, the results would be significantly overestimated. The new ICRP (ICRP-66) respiratory tract model also grossly underestimates urinary excretion of inhaled poorly transportable uranium compounds and exacerbates the problem, at least for the default values of the parameters of the model. A lung model derived from the original ICRP-30 lung model, which is named “modified,” has been proposed in this work. It predicts urinary excretion better, even though it is not entirely satisfactory in predicting urine/fecal ratio in excreta.

The method for absolute estimation of software quality for doublet deconvolution based on a system of penalty points is presented. The method developed is an effective means as for independable and correspondence competition of programs for doublet processing and for fine tuning of these programs. The application of the suggested method is demonstrated and discussed on the example of test spectrum No. 400 by IAEA.

Accelerator-based 14-MeV or fast neutron activation analysis (FNAA) is a mature tecnique and few major advances in instrumentation and methodology can be expected. However, applications of the technique are numerous and continue to increase. In this paper, recent technique developments and applications of FNAA are reviewed and speculations concerning future progress in the field are presented.

¹⁵N induced radioactivation was used to study the possible trace determination of light elements with 1≤Z≤17. 55 nuclear reactions were investigated with ion beam energies ranging from E_1ab=10 MeV to E_1ab=30 MeV. Three elements were found to be determinable non-destructively, selectively and sensitively: Li, Be and Mg. Nuclear interferences have also been defined and quantified. The technique has been tested by analyzing NBS standards. Finally, Li and Be have been determined in glass samples and Mg in various types of alumina.

Methods for simultaneous determination of europium and terbium based on concentration dependent distribution is described. With these methods, the distribution ratios of elements are measured in two types of substoichiometric systems. Possibility of determining these elements simultaneously is investigated experimentally by using two pairs of substoichiometric complexans/excess extracting agents, such as DTPA/HTTA and EDTA/HTTA. Relative errors and precisions for simultaneous determination of the elements are less than 5%.

A new internal standard method for activation analysis has been developed. This method is characterized by that a suitable element present originally in the sample is used as an internal standard and the comparative standard is prepared by applying the standard addition method to the duplicated sample. When a sample under examination contains W_ag of trace element A to be determined together with a known amount of element B which is usable as an internal standard, and when the comparative standard is prepared by adding W _a^* g of accurately known small amount of the element A to the duplicated sample, even if the sample and comparative standard are irradiated separately by particles with different fluxes, W_a can be determined, easily by using the following equation: W_a=W _a^* /[(A _R^* /A_R)-1] Where A_R and A _R^* are counting ratios of gamma-rays emitted by two radioactive nuclides produced from the element A and B in the sample and comparative standard, respectively. Neither correction of the inhomogeneities of flux between the sample and comparative standard, nor that of, the self-shielding effects are necessary for the present method. The usefulness of the method was examined through the determination of Co, Ni, Rb and Sr in pepperbush by means of photon activation, and the precision and accuracy of the method were proved to be valid.

The μm-PIXE setup of Fudan University has been used to study the trace elements of ostracode shells. Program TSPIXE was used to calculate their trace element concentrations.Stenocypris derupta Vavra, Dolerocypria mukaishimensis okubo andTanella opima Chen, three kinds of ostracodes were analyzed. In this study, we concentrate on the relationships between molar ratios of Mg/Ca and temperature, and between molar ratios of Mg/Ca and salinity of the host water. We have found that the molar ratios of Mg/Ca of ostracize shells are positively correlated with the temperature of the host water, but negatively correlated with its salinity.

Glasses are suitable host matrices for the immobilization of high-level radioactive wastes. The corrosion behaviour of nuclear waste glass in water is of considerable importance, since a potential route for returning of radionuclides to the biosphere is their leaching from the waste form into groundwater and subsequent transport by the groundwater to the surface. In this study, the preparation and characterization of borosilicate glasses of different chemical composition were investigated. Borosilicate glasses were doped with simulated nuclear waste oxides. The chemical corrosion in water of these glasses was followed by measuring the leach rates (g·cm⁻²·day⁻¹), as a function of time. It was found that a simulated nuclear waste glass with the chemical composition (weight %), 15.61% Na₂O, 10.39% B₂O₃, 45.31% SiO₂, 13.42% ZnO, 6.61% TiO₂ and 8.66% waste oxides, is characterized by low melting temperature and with good corrosion resistance in water. Influence of passive layers on the leaching behaviour of nuclear waste glasses is discussed.

The effect of the degree of iodination on the enzymatic activity of two enzymes, phospholipase A₂ (fraction k₁) and cathepsin D, was studied. The compounds were labelled with¹³¹I₃ and¹³¹ICI ₂⁻ prepared by electrolysis at a controlled electrode potential. To avoid excessive denaturation of the enzyme, the electrophilic reagent was produced separately and added to the enzyme solution. Unreacted iodine species were removed by means of gel chromatography on Sephadex G-25. Enzymes were also radioiodinated by a chemical method, using chloramine T as oxidant, the results being compared with those obtained by the electrochemical method.

At the National Institute of Standards and Technology, there are two techniques for chemical analysis that use neutron beams from the reactor for target irradiation: neutron depth profiling (NDP) and prompt γ-ray activation analysis (PGAA). There are two facilities for each technique, one equipped with a thermal neutron beam and the other, with a cold neutron beam. In addition, focused beams of cold neutrons will be used to measure the two-dimensional element distributions by PGAA and three-dimensional distributions by NDP. This paper includes a brief description of the facilities, the measurement capabilities of each, some recent applications of NDP and PGAA, and neutron focusing as applied to these techniques.

A collection-precipitation (CP) method and an extraction-collection-precipitation (ECP) method have been investigated for high speed and efficient recovery of palladium from reprocessing waste of spent nuclear fuel. For the CP method, a matrix feedstock solution and a small volume of inert solvent, whose specific gravity is greater than that of feedstock solution, as collecting and protective agent, were powerfully mixed with an appropriate amount of potassium iodide solution at 15°C for 1 minute, recovering PdI₂ precipitate after centrifuging. For the ECP method, an extraction complex K(benzo-15-crown-5)₂I in the same organic solvent as for the CP method was mixed with feedstock solution. For both methods, the percent recovery of palladium is more than 99% and 95% for irradiation doses of 1·10³ and 5·10³ Gy, respectively. Decontamination of the palladium product is good.

A systematic study of extraction of pertechnetate with tetraphenylarsonium chloride (TPAC) in chloroform from aqueous chloride solutions has been carried out at 25°C at ionic strength of 1.0. Fundamental parameters governing the distribution equilibrium of TPAC were determined. Extraction behavior of pertechnetate was established on the basis of the distribution mechanism of TPAC.

Bombardment conditions, chemical separation, and counting method were examined for routine determination of carbon, nitrogen, and oxygen in various matrices by charged-particle activation analysis with respect to reliability, reproducibility, simplicity, and rapidity. A system was then set up for trustworthy measurement of these elements.

The behaviour of the elements Zr, Hf, Nb, Ta and Pa has been investigated on macroporous anion exchange resin BIORAD AGMP 1 in HF medium (from 0.02 to 2M). All the studied elements show strong adsorption properties at low HF concentration. The adsorption was found to be highly dependent on H⁺ and F⁻ concentrations. The distribution of possible adsorbable complexes is discussed.

Recently developed methods for the rapid, quantitative analysis of americium (Am), curium (Cm), and plutonium (Pu) isotopes in Hanford soil, sludge, and waste-tank samples are described. After dissolution, dilutions are made as necessary based on alpha-energy analysis of a small aliquot of the original solution. Isotopic tracers are then added and Am-Cm and Pu are separated by extraction chromatography, coprecipitated with neodymium fluoride, and counted. Examples of alpha spectra are given, and results obtained for Hanford sludge samples are presented.

Nuclear and radiochemistry offers special and attractive possibilities for exploring the fascinating world of closed-shell carbon cages called fullerenes. This review presents a panoramic view on the use of radioactivity, nuclear irradiation and instrumental nuclear techniques in the elucidation of the structure and composition of fullerenes and their compounds.

Mantle-derived magmatites from the Saxonian Granulite Massif have been investigated by instrumental und radiochemical NAA. Pd, Ir and Pt were separated after irradiation by extraction with DDTC and DBDTO. Cs was precipitated by sodium tetraphenyl borate, the REE were isolated by cation exchange and the activation products of thorium and uranium by extraction with TOPO. The Lower-Riphean and Upper-Riphean magmatites contain sequences of partial melting and fractionated crystallization. They start from ultramafic garnet serpentinites with the composition of primary earth mantle. The contents of platinum group elements in garnet serpentinites amount to about 1% those of Cl chondrites. In depleted serpentinites, which are residues of partial melting, the concentration of Pd is reduced by a factor of 4.5.

Extraction of Co(II) from perchlorate aqueous media by mixtures of thenoyltrifluoroacetone and triphenylarsine oxide or triphenylphosphine oxide in chloroform has been studied. It is found that the presence of these oxides enhances the extraction of Co(II). Synergic factors and formation constants were calculated and interpreted in the light of the electron donating properties of these oxides.

A method for labeling of anti-carcinoembryonic antigen (CEA) monoclonal antibody (MAb) BW 431/26 is described. For preparations of^99mTc-anti-CEA complex, a solution (1 ml) of tetrasodium-1,1,3,3-propanetetetraphosphate dihydrate (2.7 mg), stannous chloride dihydrate (0.12 mg) and sodium chloride (0.2 mg) in 5 ml of 0.9% saline was added to a vial containing monoclonal antibody (2 mg) from mouse (MAb BW 431/26), D-glucitol (2 mg) and sodium sulfate (2 mg) to obtain a clear solution. A quantitative labeling yield of the MAb BW 431/26 was achieved by addition of 5 ml (40.5 mCi, 1.5 Gbq) technetium-99m-pertechnetate (^99mTcO₄) generator eluate at room temperature within 10 minutes. The radiochemical purity determined by ITLC (Gelman, SG) plates was >95%.

A simple method employing neutron activation and radiochemical separation was developed for simultaneous determination of the concentrations of²³²Th(Th) and²³⁸U(U) in biological materials. Using this method, it is possible to detect 0.05 and 0.2 ng of Th and U, respectively, in the samples. This method was applied to determine the daily dietary intake of these two nuclides by the population living in the high background areas of India (Monazite area), where the soil contains very high levels of these two nuclides. The comparison of the daily intakes by the population living in high and normal background areas showed significantly higher intake of these two nuclides by the high background population.

A post-K_o study of parametric reactor NAA is described including the determination and applications of working K_oS for non-1/V reactions¹⁵¹Eu(n,γ)¹⁵²Eu and¹⁷⁶Lu(n,γ)¹⁷⁷Lu; parametric corrections for²³⁵U fission, threshold reaction and γ-spectral interferences; and parametric normalizations for different counting geometries. The analytical significance, the principles, the experimental confirmations, and the application examples of these methods are briefly introduced.

Uptake of radiostrontium by sediments from two small streams was studied as a function of pH and composition of aqueous phase, of the concentration of strontium, of contact time, temperature and liquid-to-solid ratio (V/m), using laboratory model experiments. Between pH 5 and 12 the uptake increased with pH and shifted to higher pH values with increasing V/m ratio. Addition of cations suppressed the uptake in the order Na⁺<K⁺<Ca²⁺. Increase in strontium concentration had negligible effect up to 10⁻⁵–10⁻⁴ mol·dm⁻³ concentration due to high concentrations of dissolved and exchangeable strontium present in the systems. The V/m ratio had no influence on K_d in the range of V/m=20–446 cm³ · g⁻¹ but K_d value for V/m=0.79 cm³ · g⁻¹ was significantly lower. Two-step kinetics of the uptake was observed in most cases with a rapid first step (<100 min) followed by a slow increase. No difference was found between the uptake at 10°C and 22°C. Adsorbed radiostrontium could be easily desorbed with river water. The easiness of desorption decreased with repeated desorption. Drying of sediment did not affect the first desorption, repeated desorptions slightly decreased. Conclusions were drawn on the mechanism of radiostrontium uptake and on the importance of the factors studied for modelling of radiostrontium migration in rivers.

In order to produce routinely carrier-free⁹⁶Tc and¹¹¹In, their simultaneous production was examined by means of the stacked foil method. Both niobium and silver foils were arranged on the target holder so as the desired nuclear reactions took place effectively. Simultaneous irradiation of the target with 35 MeV α-particles produced effectively¹¹¹In and⁹⁶Tc by the¹⁰⁹Ag(α, 2n)¹¹¹In and⁹³Nb(α, n)⁹⁶Tc reactions, respectively. Sufficient amounts of radioactivities for tracer uses are obtained by the irradiation at 5 μA current for 2 hrs. In addition, carrier-free⁹⁶TcO₄⁻ in a perchloric acid solution could be prepared by the combined use of precipitation and anion-exchange methods. Separation of carrier-free¹¹¹In from the silver matrix was done by means of solvent extraction using acetylacetone as a chelating agent.

Tritium concentrations are reported for diet and human tissue samples collected in the Akita district of northern Japan. Sixteen separate food group samples and a total diet sample were collected for Akita City during April and May 1987. Six samples of heart and nine samples of kidney tissue were collected from 10 decreased individuals in Akita Prefecture from January to July 1986. Five serum and four blood samples were also obtained in Akita Prefecture from December 1985 to June 1986. Free water³H concentration as well as tissue-bound³H were determined separately. Specific activity ratios of tissue-bound³H to free water³H in the samples were almost between 1.0 and 2.0 and were similar to our previous results for food samples and other tissue samples. The specific activity ratio was also found to be lower than that reported in the U.S.A. and significantly lower than in Europe.

In order to examine effective applications of the newly developed internal standard method, determinations of Cr, Co, Ni, Zn, As, Rb, Sr, Y, Zr, Nb, Cs, Ce and Pb in three environmental materials, such as pond, lake and estuarine sediments, have been tried by means of photon activation. In these examinations, some major constituent elements in the above sediments were properly used as excellent and effective internal standards. In consequence, it was confirmed that highly accurate and precise determinations of the above 13 elements were achieved easily and favourably.

Instrumental Neutron Activation Analysis (NAA) has been applied for the determination of Ag and Sb in water column, sediment cores, and two marine organisms from Saronikos Gulf, Greece. Higher levels of Ag and Sb were found in the water column and cores from polluted areas of the Gulf as compared to those from unpolluted areas. No significant differences of Ag and Sb were found in the two marine organisms from all areas of Saronikos Gulf.

A simple and rapid method has been developed for the separation and purification of plutonium from solid analytical waste (containing uranium, plutonium, nickel and graphite) generated during the analysis of the nuclear fuels for their oxygen and nitrogen contents by inert gas fusion technique. The method is based on crushing the graphite crucibles, electromagnetic separation of plutonium-nickel alloy, dissolution in nitric acid and ion exchange purification of plutonium. Recovery of plutonium is better than 98%. The method may be extendable for the recovery of any other valuable materials from such analytical waste.

Precipitate formation behavior in high-level liquid waste (HLLW) and its filtration characteristics were examined experimentally, using a simulated HLLW. The amount of precipitate formed by denitration became minimum, only at about 5% of Mo, Zr, Te and Ru, if the simulated HLLW was pre-heated until the total heat input exceeded 7.9·10⁶ J/I HLLW before denitration or denitrated with the total heat input of more than 1.1·10⁷ J/I HLLW. Under these conditions, a needle-shaped precipitate with 0.5≈1.0 μm diameter and 3≈5 μm length was formed. This precipitate can be separated easily by vacuum filtration. While, fine particles of about 0.1 μm diameter were precipitated during denitration, if the simulated HLLW was denitrated under the conditions the amount of newly formed precipitate was not minimum. It was difficult to separate the fine particles by vacuum filtration.

Using 1.0 MeV protons on thick targets of zeolite pellets, aluminium and silicon were determined by PIXE. Results were compared with XRF data. The relative root mean square error was 3.7% and the results of the two methods agreed with a correlation factor of 0.991. PIXE analysis can be carried out on very small samples, while sample preparation involves minimal handling.

A radiochemical separation method using Dowex 1×8 (200–400 mesh) has been applied to two tantalum metals of 99.9% purity. While tantalum was still retained on the resin, the elements Na, K, Cr, Mn, Fe, Co and Zn were separated with 2M HF and subsequently the elements Sc, As, Zr, Mo, Eu, W and Hf with a mixture of 0.5M HF and 3M HCl. The separation yields for all impurities was 98–100%. Elemental contents were calculated by a single comparator method using two monitors.

Based on the fundamental parameters governing the distribution equilibrium of tetraphenylarsonium chloride (TPAC) between then-hexane-chloroform and aqueous solutions, the extraction mechanism of pertechnetate with TPAC has been systematically investigated. By the analysis of a relation of the distribution ratio of pertechnetate and the hydrogen ion concentration, the dissociation constant of pertechnetic acid was determined to beK_a=2.09±0.18 at 25 °C.

Low-level methods for the determination of iridium and other noble metals have become increasingly important in recent years due to interest in locating abundance anomalies associated with the Cretaceous and Tertiary (K-T) boundary. Typical iridium anomalies are in the range of 1 to 100 μg/kg (ppb). Thus methods with detection limits near 0.1 μg/kg should be adequate to detect K-T boundary anomalies. Radiochemical neutron activation analysis methods continue to be required although instrumental neutron activation analysis techniques employing elaborate gamma-counters are under development. In the procedure developed in this study samples irradiated in the epithermal neutron facility of the U. S. Geological Survey TRIGA Reactor (Denver, Colorado) are treated with a mini-fire assay technique. The iridium, gold, and silver are collected in a 1-gram metallic lead button. Primary contaminants at this stage are arsenic and antimony. These can be removed by heating the button with a mixture of sodium perioxide and sodium hydroxide. The resulting 0.2-gram lead bead is counted in a Compton suppression spectrometer. Carrier yields are determined by reirradiation of the lead beads. This procedure has been applied to the U.S.G.S. Standard Rock PCC-1 and samples from K-T boundary sites in the Western Interior of North America.

The ratio of the hydrogen and manganese neutron absorption cross sections, σ_H/σ_Mn, is a most important parameter in the determination of radioactive neutron source strength by the manganese bath technique. The ratio is well measured by observing the change in⁵⁶Mn activity induced in the manganese bath by a fixed neutron source as the manganese concentration of the bath is changed. In the present study, the neutron source was a Maxwellian beam from²⁵²Cf. Concentrations were determined by the two methods: volumetric and gravimetric. The cross section ratio has turned out to be σ_H/σ_Mn=0.02506.

The use, for analysis, of K X-rays proceeding from metastable and beta-emitting radionuclides—produced by neutron activation—is an undeveloped aspect of activation analysis. Consequently, this study examines the feasibility of applying X-ray spectrometry to isotope source activation analysis and in particular the determination of Sm and Eu at low levels is described. Generally speaking, the sensitivity is seriously restricted by the thermal neutron flux of the source but in certain specific cases the analysis is favoured by the nuclear properties of the elements concerned. Therefore, the selection of elements was based largely on their demand for analysis and their ability to produce a practicable yield. Optimum signalto-noise ratios were attained by employing a detector that was particularly sensitive at energies below 150 keV. Analytical conditions are demonstrated for the elements of interest over a wide range of concentrations in small samples, and ultimately the applicability of the method was tested by the analysis of a typical monazite sample. The analytical potential of the method is thoroughly appraised and possible practical applications are discussed.

In order to assess the levels and behavior of¹²⁹I (half-life: 1.6×10⁷ y) and¹²⁷I (stable) in the environment, we have developed analytical procedures involving neutron activation analysis (NAA). Environmental samples collected around Tokaimura, Ibaraki Prefecture, Japan, have been analyzed using this method. Ranges of¹²⁹I and¹²⁷I concentrations in surface soil were 0.9–180 mBq kg⁻¹ and 1–60 mg kg⁻¹, respectively. Higher¹²⁹I concentrations were found in soil samples collected from coniferous forests, suggesting a contribution from tree canopies in the deposition of this nuclide. Most of the¹²⁹I in soil, was found to be retained in the first 10 cm. The¹²⁹I/¹²⁷I ratios in wheat fields were lower than those in rice paddy fields.

A soil sample collected by IAEA from an area contaminated by the Chemobyl accident was also determined. The¹²⁹I concentration and the¹²⁹I/¹²⁷I ratio were 1.6 mBq kg⁻¹ and 1.7×10⁻⁷, respectively. The¹²⁹I level in this sample was higher than the values obtained in areas far from nuclear facilities in Japan. It was suggested that the analysis of¹²⁹I in soils in the Chernobyl area may be useful in evaluating the¹³¹I levels at the time of the accident.

Analyses of¹²⁹I and¹²⁷I by ICP-MS in water samples were also made. The analytical speed of this method was very high, i.e., 3 minutes for a sample. However, there is a sensitivity limitation for¹²⁹I detection due to interference from¹²⁹Xe with the¹²⁹I peak. The detection limits for¹²⁹I and¹²⁷I in water samples were about 0.5 mBq ml⁻¹ and 0.1 ng ml⁻¹, respectively.