Geographical distribution of plutonium derived from the atomic bomb in the eastern area of Nagasaki

In order to know the distribution of plutonium derived from the Nagasaki atomic bomb, soil samples were measured to determine the ²⁴⁰Pu/²³⁹Pu isotope ratio of and concentrations of ^239+240Pu and ¹³⁷Cs. The ^239+240Pu concentrations in soils, except for Nishiyama area, were close to the average concentration of soil collected in Japan. In soils collected at the Nishiyama area and at the eastern area of Nagasaki Prefecture and at part of northern area in Kumamoto Prefecture, the ²⁴⁰Pu/²³⁹Pu ratios were lower than the global fallout values. This suggests that plutonium from the atomic bomb was deposited in the eastern area from the hypocenter reaching up to 100 km eastwards.     

Validation of an extraction paper chromatography (EPC) technique for estimation of trace levels of 90Sr in 90Y solutions obtained from 90Sr/90Y generator systems

While the extraction paper chromatography (EPC) technique constitutes a novel paradigm for the determination of few Becquerels of ⁹⁰Sr in MBq quantities of ⁹⁰Y obtained from ⁹⁰Sr/⁹⁰Y generator, validation of the technique is essential to ensure its usefulness as a real time analytical tool. With a view to explore the relevance and applicability of EPC technique as a real time quality control (QC) technique for the routine estimation of ⁹⁰Sr content in generator produced ⁹⁰Y, a systematic validation study was carried out diligently not only to establish its worthiness but also to broaden its horizon. The ability of the EPC technique to separate trace amounts of Sr²⁺ in the presence of large amounts of Y³⁺ was verified. The specificity of the technique for Y³⁺ was demonstrated with ⁹⁰Y obtained by neutron irradiation. The method was validated under real experimental conditions and compared with a QC method described in US Pharmacopeia for detection of ⁹⁰Sr levels in ⁹⁰Y radiopharmaceuticals.     

Detection of wood discoloration in a canker fungus-inoculated Japanese cedar by neutron radiography

Summary Neutron radiography (NRG) was applied to trace the development of discolored tissue in the wood of Japanese cedar (<Emphasis Type=Italic>Cryptomeria japonica</Emphasis>) after being infected with a canker fungus. Japanese cedar seedlings were wound inoculated with a virulent and avirulent isolate of a canker fungus, <Emphasis Type=Italic>Guignardia cryptomeriae</Emphasis>. Three, 7, 13 and 22 days after the inoculation, the seedlings were irradiated with thermal neutrons. The image on the X-ray film showed that the whiteness in the image corresponded to the water content in the sample. Discolored tissue and surrounding dry zones induced by the fungal inoculation were detected as dark areas, indicating water deficiency with a high resolution. Through image analysis, the dry zones were detected as early as 3 days after inoculation. Neutron images also showed the difference in the size of water deficient parts due to the tissue damage among the treatments. The neutron beam dose used in this experiment had no effect on the growth rate of the fungus on a medium, showing that NRG is an effective method for pathological research of trees.     

Accumulation of90Sr in sheep bones from different regions of Turkey

In this study, the accumulation of⁹⁰Sr in front leg bones of sheep (meta carpus), which were 1–6 years old and originated from different regions of Turkey, was investigated. It was shown that⁹⁰Sr activity strongly depends on the age of the sheep as well as on its origin. Since⁹⁰Sr is produced during the fissioning process of uranium isotopes in nuclear reactions, the effect of radiation due to nuclear bomb experiments, nuclear reactor accidents or other radioactive pollutants in different regions of Turkey can be concluded from the results obtained.     

Chromatographic separation of carrier free 90Y from 90Sr using a diglycolamide based resin for possible pharmaceutical applications

N,N,N',N'-tetraoctyl diglycolamide (TODGA) has been used as the stationary phase in an extraction chromatography resin (XCR) material prepared for evaluating the uptake and the separation behaviour of (90)Y and (90)Sr from acidic feeds. Chromosorb-W was used as the solid support material while the feed solution was usually 4M HNO(3). The batch uptake studies have suggested almost no Sr(II) uptake while Y(III) uptake increased with acidity up to 4M HNO(3) beyond which a decrease in the K(d,w) values were observed. Column studies were carried out and breakthrough profiles were obtained for both Y(III) and Sr(II). No breakthrough of Y(III) was noticed even when >50 column volumes of the feed (carrier free (90)Y at 4 M HNO(3)) was passed through the column while about 20 column volumes were required for the breakthrough of Y(III) when the feed contained 1 g/L Y in 4 M HNO(3) spiked with (90)Y tracer. The reusability of the column was also studied which indicated in the deterioration of the column performance as shown by the sharp fall in the breakthrough volumes and was attributed to the probable leaching of the reagent from the support material. The role of absorbed dose was also investigated for Y(III) uptake. Separation of carrier free (90)Y tracer was carried out by loading the column with (90)Sr and eluting with 0.01M solutions of HNO(3) as well as EDTA. The purity of the product was ascertained by half-life method.     

Determination of 90Sr in radioactive concentrate from Nuclear Power Plant Mochovce

This paper describes the use of molecular recognition technology product AnaLig^®Sr-01 gel from IBC Advanced Technologies, Inc. to effectively and selectively pre-concentrate, separate and recover strontium from evaporator concentrate samples from Nuclear Power Plant Mochovce which belongs to the most difficult matrices to analyze. The method is suitable for analyzing highly contaminated samples of radioactive waste in a relatively short time and with high decontamination factors. Activity of ⁹⁰Sr was measured using Cherenkov counting on TRI CARB 2900 TR liquid scintillation counter.     

Deposition of90Sr and plutonium isotopes derived from the Chernobyl accident in Japan

To clarify environmental effects of the Chemobyl radionuclides, long-lived Chernobyl radioactivity (^239,240Pu,²³⁸Pu,²⁴¹Pu and⁹⁰Sr) in deposition samples in May 1986 was measured at 11 stations in Japan. Temporal variation of weekly deposition of⁹⁰Sr differed from that of volatile radionuclides such as¹³¹I and¹³⁷Cs, which may reflect the released process at Chernobyl. On the other hand, the geographical distributions of the monthly deposition of long-lived radionuclides were similar to those of volatile radionuclides, in which maximum deposits of⁹⁰Sr and plutonium were observed in Akita, a northwestern Japan Sea coast site of Honshu Island. Higher²⁴¹Pu deposition in most of the stations, as well as high²³⁸Pu/^239,240Pu activity ratios were observed. The²⁴¹Pu/²³⁸Pu activity ratios in deposition samples were nearly equal to that in the total release, which is clear evidence that Chernobyl-derived plutonium was transported to Japan in May 1986 together with volatile radionuclides although the contribution of Chernobyl Pu was about three orders of magnitude lower than¹³⁷Cs.     

On a Pure Instrumental Method of 90Sr Determination in Bone Samples

An attempt is presented for the measurement of ⁹⁰Sr in real animal bone samples using gamma-ray spectrometry only with germanium detector. Gamma-ray spectra of bone samples are de-convoluted and the residue bremsstrahlung effect from ⁹⁰Sr-⁹⁰Y beta-radiation is observed. The validation of the proposed method was done by standard ⁹⁰Sr determination including radiochemical separation and liquid scintillation spectrometry (LSS). The Pearson correlation factor obtained between the activity determined by LSS and the proposed instrumental method was 0.57, with the achieved efficiency of 0.12%. Possible improvements of the method are suggested.     

Investigations of the migration of elements in tree rings by Laser-ICP-MS

The autocorrelation function of the concentration of elements in growth rings has been used to study their migration from ring to ring. The correlation time which can be calculated by the autocorrelation function gives an indication of the transport of elements. However, a large correlation time might only be taken as a necessary criterion for the migration but not for a sufficient one. Laser sampling-ICP-MS has been used for the determination of the contents of elements in the rings of an 150 years old oak – the autocorrelation functions of selected elements have been calculated. Large correlation times have been only obtained for Ca, Fe and Cr. It may be concluded that Mg, Zn, Cu, Sr, Pb, Ni, Ba, Al and Mn hardly migrate radially in the trunk of an oak.     

Ceric phosphate as ion exchanger in the separation of carrier-free210Bi from210Pb,90Y from90Sr and UX1 from u

Separations of tracer cations in parent daughter systems such as carrier-free²¹⁰Bi from²¹⁰Pb,⁹⁰Y from⁹⁰Sr and UX₁ from U have been carried out in a column of ceric phosphate as ion exchanger. The exchanger has been prepared by mixing ceric sulfate in hot 10M orthophosphoric acid at 80°C and keeping for overnight. A pale yellow coloured precipitate was formed which was washed, dried at 70°C for 48 hours when a hard, granular variety suitable for column use, with a cerium to phosphate ratio of 1∶2 was obtained. 0.1M H₃PO₄ was used as medium in each of the systems studied. The β-decay curves of the separated²¹⁰Bi and⁹⁰Y and the γ-spectrum of UX₁ show that all these activities are radiochemically pure. The separation procedures adopted in each case were very clean and simple, gave quantitative yields and took less than half an hour.     

Sodium titaniumsilicate as ion exchanger: synthesis, characterization and application in separation of 90Y from 90Sr

A new inorganic material, sodium titaniumsilicate has been synthesized, and characterized by physicochemical and spectroscopic tools. The thermal and radiation stability of the compound was checked by TGA technique and a ??-irradiating chamber with a total dose rate of 5?kGy/h. The compound is highly stable towards thermal, chemical and total radiation dose of 64?kGy. The study of the exchange capacity of the material towards different alkali and alkaline earth metal ions showed that the sorption capacities of the alkali metal ions were greater than those of alkaline earth metal ions. The crystalline state of this new inorganic material is very useful as an inorganic ion exchanger to have the carrier free short-lived ??-active daughter product ⁹⁰Y from the long-lived ⁹⁰Sr of the radioactive equilibrium mixture. The absorbed daughter was recovered by using 1.0% EDTA solutions at pH 7.0 as eluting agent. The features and trends in elution are encouraging to apply this material as an exchanger in radionuclide generator system.     

Investigations of the migration of elements in tree rings by Laser-ICP-MS

The autocorrelation function of the concentration of elements in growth rings has been used to study their migration from ring to ring. The correlation time which can be calculated by the autocorrelation function gives an indication of the transport of elements. However, a large correlation time might only be taken as a necessary criterion for the migration but not for a sufficient one. Laser sampling-ICP-MS has been used for the determination of the contents of elements in the rings of an 150 years old oak - the autocorrelation functions of selected elements have been calculated. Large correlation times have been only obtained for Ca, Fe and Cr. It may be concluded that Mg, Zn, Cu, Sr, Pb, Ni, Ba, Al and Mn hardly migrate radially in the trunk of an oak.     

On the reliability of a rapid method for the determination of90Sr in natural samples

A method for the rapid evaluation of⁹⁰Sr in environmental matrices has been developed. It is a one-day time-consuming procedure compared with 20–25 d of the traditional methods. It is based on a partial measurement of the sample activity and on data extrapolation. This work reports the methodology and its reliability.     

An electrochemical pathway to prepare circular planar 90Sr/90Y sources for the calibration of surface contamination monitors

In this communication, we describe a novel method to prepare circular planar ⁹⁰Sr/⁹⁰Y sources (? = 16 mm) exploiting the intrinsic properties of the anodized titanium to electro-deposit predicted quantity of ⁹⁰Sr activity from an aqueous solution. The influences of various experimental parameters such as pH of the electrolyte, applied current density, electrodeposition time and carrier strontium concentration were thoroughly investigated to arrive at a condition resulting optimal deposition of the ⁹⁰Sr/⁹⁰Y activity on the substrate. An optimized electrochemical procedure to prepare ~3.7 MBq (~0.1 mCi) of circular planar ⁹⁰Sr/⁹⁰Y sources commensurate with regulatory safety requirement has been the positive outcome.     

Determination of low-level90Sr in environmental materials: A novel approach to the classical method

A method was developed for the separation of strontium from large amounts of calcium which does not depend on fuming nitric acid. A sample in the form of mixed carbonates or oxides is stirred into concentrated nitric acid in the proportion 17 w/v. Strontium forms insoluble nitrates while calcium remains in the solution. Two re-precipitation steps combined with an acetone wash yield a very pure strontium salt which is suitable for gravimetric determination of recovery. The method, devised originally for⁹⁰Sr assay in sea water, can also be applied to solid samples which present analytical problems due to their high calcium content.     

Transfer of 7Be, 210Pb and 210Po in a forest canopy of Japanese cedar

The concentrations of ⁷Be, ²¹⁰Pb and ²¹⁰Po of ca. 60 parts of a whole tree of Japanese cedar and of underlying litter and soil samples were determined for studying their transfer in a forest canopy. The results suggest that the mean residence times of ⁷Be and ²¹⁰Pb in the forest canopy were ca. 20 and 900 days, respectively, and the dry deposition rate of ⁷Be on the forest canopy was about a half of the total deposition rate.     

Fractionation of cesium isotopes and90Sr in snowmelt run-off and lake waters from a contaminated Norwegian mountain catchment

Cesium isotopes and⁹⁰Sr have been determined in the inflow and outflow rivers of a Norwegian subalpine lake. The lake is situated in an area contaminated by Chernobyl fallout. Sampling was carried out during the spring peak discharge period associated with snowmelt. Transported coatse particulate plant material was collected by traps. Particles and colloids were removed from water samples by hollow fibre ultrafiltration. The results illustrate that run-off during the spring snowmelt is an important pathway for these radionuclides. The cesium isotopes are predominantly transported as colloids, while⁹⁰Sr is present in the form of low molecular weight mobile species. Based on lake budget calculations, more than 50% of the cesium input is retained in the lake, while more than 90% of the⁹⁰Sr is transported through the lake and into lower parts of the drainage system.