Decontamination of radioactivity from contaminated vegetables derived from the Fukushima nuclear accident

Many kinds of vegetables were contaminated by a huge amount of radioactivity, such as ¹³¹I or ¹³⁷Cs, derived from the Fukushima nuclear accident. The concentration of radioactivity in contaminated vegetables was higher than the value of the legal limit for shipment, therefore, we attempted to identify a simple and effective removal method for contaminated farm products to ensure the relief of farmers and the security of consumers. First, the radioactivity distribution and adhesion state of contaminated vegetables were investigated by an imaging plate (IP) image. As a result, there were two types of contamination, spot type or spread type, of vegetables. The removal of radioactivity by physical or chemical methods was investigated. As a result, radioactivity removal by water washing showed no significant difference between boiling water and cold water. There was no significant difference between hand washing and running water washing. The result of chemical removal showed that reducing agents removed radioactivity from vegetables by 70–80% for ¹³¹I and more than 80% for ¹³⁷Cs. In particular, ascorbic acid is promising as a safe and versatile option.     

Two-proton radioactivity of ground and excited states within a unified fission model

A unified fission model is extended to study two-proton radioactivity of the ground states of nuclei, and a good agreement between the experimental and calculated half-lives is found. The two-proton radioactivity half-lives of the ground states of some probable candidates are predicted within this model by inputting the released energies taken from the AME2020 table. It is shown that the predictive accuracy of the half-lives is comparable to those of other models. Then, two-proton radioactivity of the excited states of ¹⁴O, ^17,18Ne, ²²Mg, ²⁹S, and ⁹⁴Ag is discussed within the unified fission model and two analytical formulas. It is found that the experimental half-lives of the excited states are reproduced better within the unified fission model. Furthermore, the two formulas are not suitable for the study of two-proton radioactivity of excited states because their physical appearance deviates from the mechanism of quantum tunneling, and the parameters involved are obtained without including experimental data from the excited states.     

Cubic potential models for cluster radioactivity

Cluster radioactivity is a process by which nuclei equal and heavier than the α-particle is emitted spontaneously. The clusters usually emitted in this process are the α-particle, carbon, oxygen, neon, magnesium, silicon etc. When the mass of the cluster becomes comparable with the mass of the daughter, symmetric fission takes place. Thus the cluster radioactivity is an intermediate process between the well known α-decay and the spontaneous fission. In earlier years such cluster radioactivity was found mostly in actinide nuclei like radium, uranium etc. Very recently it has been predicted that such decays are possible in a new region around ¹¹¹Ba. There has been an exciting experimental detection of the emission of ¹²C from ¹¹¹Ba leading to ¹⁰²Sn, which is attracting a lot of attention recently. To study the phenomenon of cluster radioactivity there are various theoretical models in vogue. The existing models generally fall under two categories: the unified fission model (UFM) and the preformed cluster model (PCM). The physics of the UFM and the PCM are completely different. The UFM considers cluster radioactivity simply as a barrier penetration phenomenon in between the fission and the α-decay without worrying about the cluster being or not being preformed in the parent nucleus. In the PCM clusters are assumed to be preborn in a parent nucleus before they could penetrate the potential barrier with a given Q-value. The basic assumption of the UFM is that heavy clusters as well as the α-particle have equal probability of being preformed. In PCM, clusters of different sizes have different probabilities of their being preformed in the parent nucleus. We have developed three fission models during the last decade using the cubic potential for the pre-scission region. The use of these models in the study of cluster radioactivity in both the actinide and barium regions will be discussed in this talk in comparison with the other existing theories.     

Cluster radioactivities of odd-mass nuclei

The partial half-lives of the hypothetical even-even equivalent of an odd-mass nucleus for cluster transitions toward various excited states of the daughter, used as a reference to find the hindrance factor, can be calculated within analytical superasymmetric fission model, by taking into account the angular momentum of the emitted cluster. Detailed tables are presented for ¹⁴C radioactivity of ²²¹Fr, ^221,223Ra, ²²⁵Ac; ²⁴Ne radioactivity of ²³³U, ²³¹Pa, and ²³F decay of ²³¹Pa, showing that, except for ²²⁵Ac, the existing experimental evidences, do not exclude (moderate) hindered transitions to the ground states of the daugther nuclei.     

Assessment of natural radioactivity in rice and their associated population dose estimation

ABSTRACT

The concentration of natural radioactivity in rice is an important parameter for the determination of population exposure by the ingestion of natural radionuclides during habitual consumption of food. All types of food including rice contain a detectable amount of natural radioactivity which successively relocate into the human body via the ingestion pathway. Rice is the main cultivated crop in Bangladesh and most of the Bangladeshi people consume rice as their staple food. Hence, studies on the evaluation of natural radioactivity in rice have been performed by gamma-ray spectrometry using High Purity Germanium (HPGe) detector in order to estimate various radiation hazards due to rice consumption. The average activity levels of natural radionuclides ²²⁶Ra, ²²⁸Ra and ⁴⁰K in the rice samples were 1.09?±?0.31, 0.17?±?0.21 and 4.70?±?1.59?Bq?kg^?1, respectively. The estimated effective doses for the respective radionuclides caused by the rice consumption were 43.69, 16.39 and 4.15?µSv?y^?1, respectively which was below the UNSCEAR compiled value. The calculated excess lifetime cancer risk (ELCR) values via rice consumption were found below the acceptable limit of 0.29?×?10^?3 for radiological risk.     

Observation of fallout deposition in an outdoor swimming pool 50 km away from the Fukushima Daiichi nuclear power plant

After the accident at the Fukushima Daiichi nuclear power plant (NPP), outdoor school swimming pools at Fukushima were decontaminated to curb the redistribution of radioactivity into downstream farmlands. In the process, the radioactivity concentrations of the pool water and sediment substances (residue) were measured to estimate the deposition density of the fallout. At a pool situated 50 km away from the NPP, the average concentrations of radiocesium (^134+137Cs) for the water and residue were quantified as 170 Bq L⁻¹ and 3.6 × 10⁵ Bq kg⁻¹, respectively. Taking account of the radioactivity concentrations and of the water balance in and around the pool, the deposition density of radiocesium, as of August 2011, was precisely determined to be 0.32 ± 0.03 MBq m⁻² (k = 1). The density corroborated the previous results obtained by other methods, i.e., airborne surveys, in-situ Ge surveys and soil samplings at neighboring locations. Other than radiocesium, the only gamma-emitting nuclide detected was ^110mAg, with a concentration of 560 Bq kg⁻¹ in the residue. The radioactivity concentrations of ⁸⁹Sr, ⁹⁰Sr, ²³⁸Pu and ^239+240Pu in the water were all less than the minimum detectable activities – 2, 0.1, 0.002 and 0.002 Bq L⁻¹, respectively.     

Exploring music

Radioactivity in the environment includes naturally occurring as well as man-made radionuclides. Meaningful estimates of their hazard to health require much care in obtaining representative environmental samples, appropriate sample preparation as well as proper calibration of the measuring system. Any harm from the low absorbed doses of ionizing radiation typically received from environmental radioactivity would only occur after a latent period of several years. Of these, cancer induction is considered to be the most important. Risk factors have been derived by a number of internationally recognized organizations, but there are difficulties in extrapolating from observations at a high dose and dose rate and for the lifetime of exposed populations. Examples of measurement of ²²²Ra, ⁹⁰Sr, ¹²⁵I, ²²⁶Ra, ¹²⁹I and ¹³⁷Cs in the environment are given. Harmful effects from environmental radioactivity have mostly been indistinguishable above natural incidence. For health purposes there may be little need for further increases in sensitivity of detection but there is a continuing need to ensure the greatest accuracy in measurements to avoid magnifying the inevitable uncertainties in estimating radiation hazards.     

Proton radioactivity at non-collective prolate shape in high spin state of Ag

We predict proton radioactivity and structural transitions in high spin state of an excited exotic nucleus near proton drip line in a theoretical framework and investigate the nature and the consequences of the structural transitions on separation energy as a function of temperature and spin. It reveals that the rotation of the excited exotic nucleus ⁹⁴Ag at excitation energies around 6.7 MeV and angular momentum near 21? generates a rarely seen prolate non-collective shape and proton separation energy becomes negative which indicates proton radioactivity in agreement with the experimental results of Mukha et al. for ⁹⁴Ag.     

Two-proton radioactivity search

Two-proton radioactivity, a spontaneous breakup of elements with emission of two protons, was predicted to exist near the proton drip line by V.I. Goldansky long time ago. The recent theoretical and experimental progress in a search for such an exotic nuclear decay is reviewed. In theory, the new three-body model which treats two-proton radioactivity as a genuine three-particle nuclear decay is considered. In experiment, the first evidence for two-proton decay of ⁴⁵Fe is described. Four atoms of ⁴⁵Fe, produced at the fragment separator of GSI, decayed via particle emission with a total energy of 1.1(1) MeV and a half-life of 3.2 _?1.0 ^+2.6 ms. A possible experiment for a direct observation of two-proton emission from the ground state of ¹⁹Mg is considered for its decay in-flight. The half-life of ¹⁹Mg, as well as proton-proton correlations, might be derived from the distribution of the ¹⁹Mg decay vertices extrapolated from the measured trajectories of all fragments.     

238U and total radioactivity in drinking waters in Van province,Turkey

As part of the national survey to evaluate natural radioactivity in the environment, concentration levels of total radioactivity and natural uranium have been analysed in drinking water samples. A survey to study natural radioactivity in drinking waters was carried out in the Van province, East Turkey. Twenty-three samples of drinking water were collected in the Van province and analysed for total α, total β and ²³⁸U activity. The total α and total β activities were counted by using the α/β counter of the multi-detector low background system (PIC MPC-9604), and the ²³⁸U concentrations were determined by inductively coupled plasma-mass spectrometry (Thermo Scientific Element 2). The samples were categorised according to origin: tap, spring or mineral supply. The activity concentrations for total α were found to range from 0.002 to 0.030 Bq L^?1 and for total β from 0.023 to 1.351 Bq L^?1. Uranium concentrations ranging from 0.562 to 14.710 μg L^?1 were observed in drinking waters. Following the World Health Organisation rules, all investigated waters can be used as drinking water.     

14C in uranium and thorium minerals: a signature of cluster radioactivity?

Various uranium and thorium minerals have been analysed with accelerator mass spectrometry to determine their ¹⁴C content. It is found that, whenever the contribution from secondary reactions such as the ¹¹B(α,p)¹⁴C is sufficiently low, the ¹⁴C concentration is consistent with that expected from ¹⁴C (spontaneous) cluster radioactivity from radium isotopes of the uranium and thorium natural series. Received: 15 February 1999     

Search for proton radioactivity in65As,69Br and77Y

A search for proton radioactivity in⁶⁵As,⁶⁹Br and⁷⁷Y, produced as residues of fusion reactions, was carried out at the Orsay Tandem accelerator. The residues were collected at the image point of the spectrometer Soleno and implanted into the gaseous medium of an ionization chamber which was also used to detect the radioactivity protons. No such protons have been observed in the energy range of 250–600 keV and in the half-life interval of 10 μs-100 ms, within a production cross section sensitivity of 1 μb.     

Role of 208Pb daughter nucleus and nuclear shell effects in trans‐lead cluster radioactivity by emission of neon clusters from 218–236U isotopes

In the present work, the cluster radioactivity of even A uranium isotopes (^218–236U) with the emission of both alpha‐like and non‐alpha‐like neon clusters (^{20,22,24,26,28}Ne) was studied. The decimal logarithm of half‐lives (expressed in seconds) were calculated by three different approaches based on (i) the single line of Universal curve (UNIV) for alpha and cluster radioactive decay, (ii) the Universal Decay law (UDL) and (iii) by considering a fission‐like model in which the interacting nuclear potential barrier was taken to be the sum of Coulomb and proximity potentials (CPPM) respectively. Based on the half‐lives calculated by using the three different approaches mentioned above, significance of the role of ²⁰⁸Pb nucleus (doubly magic nucleus) and nuclear shell effects in trans‐lead cluster radioactivity were investigated. The calculated half‐lives have also been compared with available experimental results. It was observed that cluster decay modes leading to the formation of ²⁰⁸Pb daughter nucleus have the lowest half‐lives. This implies that there is a shell closure at proton number (Z) = 82 and neutron number (N) = 126. Hence, it confirms the existence of nuclear shell effect and stresses the significance of role of ²⁰⁸Pb daughter nucleus in the trans‐lead cluster radioactivity. It can be noticed that the calculated half‐lives for several cluster decay modes are well within the present experimental upper limit for measurements (T_1/2 < 10³⁰S). These results may be useful for future experiments.     

The potential health hazard due to elevated radioactivity in old uranium mines in Dolina Białego,Tatra Mountains,Poland

Natural radioactivity is one of the essential components of the environment. Unlike the Sudety mountains area in Poland, the Tatra Mountains were not the subject of wide survey as regards the levels of natural radioactivity. Especially, the concentrations of radon (natural radioactive gas) have not been investigated there in terms of their possible negative health impact. Within the frame of bilateral cooperation between the Institute of Nuclear Physics in Kraków, Poland, and the Jo?ef Stefan Institute in Ljubljana, Slovenia, the measurements of natural radioactive elements in old uranium mines in the Tatra National Park were performed in June 2010. The investigated sites were located in Dolina Bia?ego (The Valley of the White). One of the mines is situated near the tourist path. The paper presents the results of complex measurements of natural radioactivity in both uranium drifts. The concentration of radon gas inside the mining drifts exceeded 28,000 Bq m^?3. Also, very high gamma dose rates were observed (up to 5600 nSv h^?1). The maximum concentrations of natural radioactive elements (potassium ⁴⁰K, radium ²²⁶Ra, thorium ²³²Th) in rock samples amounted to 535, 2137, and 18 Bq kg^?1, respectively. The effective dose rates due to radon and thoron inhalation have been assessed as 0.013 mSv h^?1 (for the lowest concentration) and 0.121 mSv h^?1 (for the highest concentration).     

Radioactivity in Cervidae antlers

The experience gained in this study indicated that Cervidae antlers afford a convenient means for measuring levels of ambient radioactivity over large areas. By the use of antlers, it was possible to compare Sr⁹⁰ levels resulting from bomb testing “fallout” year by year from 1943 through 1958 in a number of areas in the United States, Canada, and Alaska. The most surprising finding was the very high levels for Alaska in 1958. From calculations based on total beta counts in antlers, it was possible to show that the radiation dose delivered to bone from short-lived fission products is insignificant as compared to the dose delivered by Sr⁹⁰/Y⁹⁰.     

15N-Markierung von Plasmaaminosäuren nach oraler Applikation von [15N]Glycin, [15N]Leucin und [15N]Hefeprotein-Thermitase-Hydrolysat

For the biosynthetic preparation of ¹⁴C-erucic acid (C₂₁H₄₁COOH) by means of rape plants cv. sollux the plants were supplied with ¹⁴CO₂ and additionally fed with ¹⁴C-Sodium acetate after anthesis. After saponification of the extracted lipids the erucic acid was isolated and purified. The substance was identified by gas chromatography. The incorporation of the applied radioactivity (34 MBq ¹⁴CO₂; 37 MBq¹⁴C-natrium acetate) into the fatty acids amounted to 1,2 per cent. The eruric acid could be isolated from the fatty acids mixture with a specific radioactivity of 1,001 MBq/mmol and a purity of 97,2 per cent.     

Unexpected radiation hazard in dyes of textiles

Textile dyes are among the most problematic pollutants because of their toxicity on several organisms and ecosystems. Many of the chemicals used in the textile industry may represent some health concerns. The determination of the radioactivity in textile dyes is therefore very important for both human health and environment. The study was designated to determine, for the first time, the values of ²³⁸U, ²³²Th and ⁴⁰K in nine different dyes employed in the textile industry using gamma spectrometry with a Hyper Pure Germanium (HPGe) detector. The mean activity concentrations of ²³⁸U, ²³²Th and ⁴⁰K were 29.37?±?4.48, 1.15?±?0.13 and 565?±?4 Bq/kg, respectively. The calculated radium equivalents for all samples were lower than the maximum admissible value (370 Bq/kg). The absorbed dose rates due to the natural radioactivity of the investigated samples ranged from 2.94?±?0.05 to 166?±?3 nGy/h. So, the absorbed dose rates for all samples of textile dyes were lower than the international recommended value (55 nGy/h) except the yellow dye (166?±?3 nGy/h), which recorded a significant radiological hazard. The external hazard index was also calculated. Conclusively, the results have indicated that the textile dyes may possess a measurable amount of radioactivity that should be taken into account. Therefore, safety rules and precautions should be applied for dyes used in the textile industry and for people working in this field.     

26Al in the interstellar medium

Several different lines of physical reasoning have converged on the importance of the radioactive nucleus ²⁶Al. The sciences of meteoritics, nucleosynthesis, gamma-ray astronomy, galactic chemical evolution, solar system formation, and interstellar chemistry all place this nucleus in a central position with possible profound implications. Perhaps more importantly the study of this radioactivity can unite these diverse fields in a complicated framework which will benefit all of them. This review traces the evolution of ideas concerning ²⁶Al in the context of these disciplines.²⁶Al was first discussed for the possibility that its decay energy could melt meteorite parent bodies, and its daughter, ²⁶Mg, was later found in meteorites with enhanced abundance. It was also among the first radioactivities expected to be synthesized in interestingly large quantities in nucleosynthetic events. The first definitive detection of gamma-rays from an interstellar radioactivity is that of 1.809 MeV gamma-rays from ²⁶Al. This discovery has many implications, some of which are outlined here. The whole problem of isotopic anomalies in meteorites is greatly influenced by the specific issues surrounding excess ²⁶Mg, whether it represents in situ decay of ²⁶Al or memory of conditions of the ISM. The relationships among these ideas and their implications are examined.     

Die Verteilung der natürlichen Radioaktivität auf das Größenspektrum des natürlichen Aerosols

The apparatus described allows to measure the distribution of natural radioactivity on aerosol particles. Careful measures were taken that the aerosol concentration and its size spectrum were not altered before being examined. To increase the accuracy of the measurements the natural aerosol was charged with thoron decay products. The resulting electric charge-distribution by ion diffusion on dust particles is known, therefore the radii of these particles could be calculated by mobility measurements. By means of the law, governing attachment of emanation decay products on dust particles — as derived byLassen orWieser andStierstadt (afterBricard), it is possible to calculate the size spectrum of natural aerosol from the measured activity spectrum. Until now we have onlyion spectra for the range of size 6×10^?7 to 10^?5 cm. With the quoted apparatus however it is possible to measure thesize spectrum of natural aerosol. So we have a simple size-spectrometer, that covers a large range of particles. Among other things can be deduced from these measurements, that the natural radioactivity of air is attached to particles of radii from 10^?6 up to 10^?5cm, — the main part of the activity being carried by aerosols with radii between 4 and 6×10^?6cm. From the calculated aerosol spectrum (r from 6×10^?7 to 10^?5 cm) follows a mean particle radius ofr=2,5×10^?6cm at a particle concentration of 3×10⁴cm^?3.     

Some proposals of new experiments on cluster radioactivity

Measurement of elastic scattering and fusion-fission cross sections of the cluster decay products is proposed for the study of the mechanism of cluster radioactivity. The obtained data on ¹²C+²⁰⁸Pb allow to select between different theoretical models. The experiment on search of the exotic nucleus ¹¹²Ba and its cluster decay is discussed.