Beta-ray Emitters Research Articles

In-situ detection of high-energy beta ray emitter 90Sr/90Y inside the Fukushima Daiichi Nuclear Power Station Unit 3 reactor building using a liquid light guide Cherenkov counter

We have developed a method to directly detect 90Sr/90Y under a high gamma ray background using a liquid light guide Cherenkov counter. Cherenkov radiation has the characteristic that the angle of radiation varies depending on the energy of the charged particles. Using this feature, we have developed a surface contamination detector capable of discriminating between 662 keV gamma rays from 137Cs and beta rays from 90Sr/90Y through time-of-flight analysis of the Cherenkov radiation generated inside the liquid light guide. With this detector, we conducted a measurement test of 90Sr/90Y inside the Fukushima Daiichi Nuclear Power Station Unit 3 reactor building and achieved the first in-situ detection of 90Sr/90Y under a high gamma-ray background.

Feasibility of a position-sensitive Cherenkov radiation detector using a reflector-coated liquid light guide

In this study, a Cherenkov radiation sensor was developed utilizing a reflector-coated liquid light guide (LLG). In the proposed configuration, a reflector replaced one of the two photomultiplier tubes (PMTs), forming the core sensing element alongside the LLG, with gamma-ray (60Co and 137Cs) and a beta-ray (90Sr) emitters employed to assess its performance as a position-sensitive detector. The time-of-flight method was utilized to determine time differences corresponding to source positions. Position spectra were generated based on these time differences, with the Cherenkov radiation count rates compared across different types of reflectors to identify the optimal choice. We compared position spectra obtained from two PMTs and one PMT with a reflector, confirming the ability to detect multiple sources. Subsequently, each source was positioned perpendicular or parallel to the sensor axis to capture position spectra. The results demonstrate the sensor's potential as a long-distance position-sensitive detector. By leveraging the simplicity of a single PMT system, the proposed sensor facilitates challenging tasks such as pipeline inspection or non-destructive testing of radioactive waste drums.

Preliminary Studies of Perovskite-Loaded Plastic Scintillator Prototypes for Radioactive Strontium Detection

Functional plastic scintillators have attracted much attention for their usefulness in on-site monitoring and detection in environments. In this study, we elucidated a highly reliable and functional plastic scintillator for detection of radioactive strontium, which means a potent perovskite-loaded polymeric scintillation material based on epoxy and 2,5-diphenyloxazole (PPO). Moreover, Monte Carlo N-Particle (MCNP) simulation was performed to optimize the thickness of a plastic scintillator for efficient strontium detection. A thickness of 2 mm was found to be the optimum thickness for strontium beta-ray detection. A newly developed plastic scintillator with 430 nm emission from perovskite loading could trigger scintillation enhancement employing potential indication of perovskite energy transfer into a photomultiplier (PMT) detector. Furthermore, the response to beta-ray emitter of 90Sr was compared to commercial scintillator of BC-400 by exhibiting detection efficiency in the energy spectrum with a fabricated perovskite-loaded plastic scintillator. We believe that this suggested functional plastic scintillator could be employed as a radiation detector for strontium detection in a wide range of applications including decommissioning sites in nuclear facilities, nuclear security and monitoring, nonproliferation, and safeguards.

Amorphization of a proposed sorbent of strontium, brushite, CaHPO4•2H2O, studied by X-ray diffraction and Raman spectroscopy

We present a systematic study of the transformation of brushite (dicalcium phosphate dihydrate, CaHPO4•2H2O) under irradiation of electrons of well-defined energy (2.5 MeV) and flux as a function of the irradiation dose. Contrarily to model hydroxides such as portlandite and brucite, which are very resistant to electron radiation damage, the studied brushite decomposes quite easily, even for very low irradiation doses. Irradiated brushite samples were characterized using X-ray diffraction (XRD) and Raman spectroscopy to get complementary information about changes in atomic structure and chemical composition respectively under irradiation. XRD showed that irradiation causes a very limited dilatation of unit cell of crystalline brushite, which becomes progressively amorphous with increasing radiation dose. Raman spectroscopy complemented XRD results and confirmed that the transformation of brushite to the amorphous phase was not abrupt, but rather progressive. Raman spectroscopy allowed for the identification of the amorphous phase as a calcium pyrophosphate. Both techniques showed that the amorphization of brushite was not fully complete at the maximum dose used, 5.5 GGy (4 C). Interestingly, monetite phase, (CaHPO4 dicalcium phosphate), was not detected at any step of the transformation as it is the case when brushite is thermally decomposed. This study reveals the high sensitivity to electron radiation of both hydrogen bonds and protonated phosphate units in brushite, thus facilitating the transformation into pyrophosphate. The damage of brushite by energetic electrons is to be carefully considered for applications related to the use of brushite as ion-exchanger in the decontamination of effluents polluted with strontium-90, an efficient beta ray emitter.

Potential Releases of 129I, 236U, and Pu Isotopes from the Fukushima Dai-ichi Nuclear Power Plants to the Ocean from 2013 to 2015.

After the Fukushima Dai-ichi nuclear accident, many efforts were put into the determination of the presence of 137Cs, 134Cs, 131I, and other gamma-emitting radionuclides in the ocean, but minor work was done regarding the monitoring of less volatile radionuclides, pure beta-ray emitters or simply radionuclides with very long half-lives. In this study we document the temporal evolution of 129I, 236U, and Pu isotopes (239Pu and 240Pu) in seawater sampled during four different cruises performed 2, 3, and 4 years after the accident, and we compare the results to 137Cs collected at the same stations and depths. Our results show that concentrations of 129I are systematically above the nuclear weapon test levels at stations located close to the FDNPP, with a maximum value of 790 × 107 at·kg-1, that exceeds all previously reported 129I concentrations in the Pacific Ocean. Yet, the total amount of 129I released after the accident in the time 2011-2015 was calculated from the 129I/137Cs ratio of the ongoing 137Cs releases and estimated to be about 100 g (which adds to the 1 kg released during the accident in 2011). No clear evidence of Fukushima-derived 236U and Pu isotopes has been found in this study, although further monitoring is encouraged to elucidate the origin of the highest 240Pu/239Pu atom ratio of 0.293 ± 0.028 we found close to FDNPP.

Dosimetry of Strontium eye applicator: Comparison of Monte Carlo calculations and radiochromic film measurements

Strontium-90 eye applicators are a beta-ray emitter with a relatively high-energy (maximum energy about 2.28 MeV and average energy about 0.9 MeV). These applicators come in different shapes and dimensions; they are used for the treatment of eye diseases. Whenever, radiation is used in treatment, dosimetry is essential. However, knowledge of the exact dose distribution is a critical decision-making to the outcome of the treatment. The main aim of our study is to simulate the dosimetry of the SIA.20 eye applicator with Monte Carlo GATE 6.1 platform and to compare the calculated results with those measured with EBT2 films. This means that GATE and EBT2 were used to quantify the surface and depths dose- rate, the relative dose profile and the dosimetric parameters in according to international recommendations. Calculated and measured results are in good agreement and they are consistent with the ICRU and NCS recommendations.

Calculated angular responses of an RPL dosemeter to photon and beta radiation

The calculated dose equivalent response as a function of the angle has been examined for the radiophotoluminescent (RPL) glass dosemeter that was exposed to narrow series X-ray, N-60, N-80, N-100, N-150, N-200, N-250, N-300, photon sources ((60)Co and (137)Cs) and beta-ray emitter ((90)Sr/(90)Y) while mounted on an ISO water slab phantom. The angular dose equivalent responses H(p)(10) and H(p)(0.07) were calculated using the Monte Carlo MCNPX code. The RPL dosemeter and the phantom were rotated in the horizontal and vertical planes from a variety of angles of interest. The results were compared with the experimental data. Good agreement was found between the measured and calculated values of the relative dose equivalent angular responses of the RPL dosemeter.

Depth Profile of Radioactivity Induced in the Thick Concrete Shield in EP1 Beam Line at the KEK 12-GeV Proton Synchrotron Facility

The evaluation of radioactivity induced in the concrete shield is important for the decommissioning of accelerator facilities. Specific activities of gamma-ray emitters of nuclear spallation products and thermal neutron capture products and beta-ray emitters such as tritium and 14C, and 36Cl in the concrete shield along the 12-GeV proton beam line (EP1 beam line, High Energy Accelerator Research Organization) were determined. The depth profiles of the radioactivity of each nuclide in the 6-m-thick concrete shield of the beam lines were compared, and the secondary particles and induced nuclear reactions were discussed.

Real-time imaging of ion uptake from root to above-ground part of the plant using conventional beta-ray emitters

We present real-time imaging of 32P-phosphate within a living plant as well as that in culture solution toward roots. The above-ground part of the plant was irradiated with light from LED and roots were kept in dark. The plant was Lotus japonicus, cv. Miyakojima MG20 and real-time 32P-phosphate uptake manners in young, flowering and adult phase were visualized. In the case of young plant, there was a preferential translocation of 32P in younger leaves. When the sample was treated with phosphate deficient condition, 32P uptake amount was much higher. In an adult phase, 32P uptake was high at pods.

Beta-Ray Dose Assessment from Skin Contamination Using a Point Kernel Method

In this study, a point kernel method to calculate beta-ray dose rate from skin contamination was introduced. The beta-ray doses rates were computed by performing numerical integration of the radial dose distribution around an isotropic point source of monoenergetic electrons called as point kernel. In this study, in-house code, based on MATLAB version 7.0.4 was developed to perform a numerical integration. The code generated dose distributions for beta-ray emitters from interpolated point kernel, and beta-ray dose rates from skin contamination were calculated by numerical integration. Generated dose distributions for selected beta-ray emitters agreed with those calculated by Cross et al within 20%, except at a longer distance where there are differences up to more than 100%. For a point source, calculated beta-ray doses were agreed well with those derived from Monte Carlo simulation. For a disk source, the differences were up to 17% at a deep region. Point kernel method underestimated beta-ray doses than Monte Carlo simulation. The code will be improved to deal with a three-dimensional source, shielding by cover material, air gap and contribution of photon to skin dose. For the sake of user’s convenience, the code will be equipped with graphic user interface.

EMILIA, the LS counting efficiency for electron-capture and capture-gamma emitters

This version includes new aspects that improve the computation of the counting efficiency for each one of the three available atomic rearrangement detection models (i.e., KLM, KL 1L 2L 3M and KLMN). The first modification involves a correction algorithm that simulates the non-linear response of the detector to photoionization for low-energy X-ray photons. Although this correction has the inconvenience of substantially increasing the number of atomic rearrangement detection pathways, the computed counting efficiency for low- Z nuclides is reduced by 2% for moderate quenching in agreement with experiment. The program also simulates how the addition of extra components, such as a quencher or aqueous solutions, affects the counting efficiency. Since the CIEMAT/NIST method requires identical ionization quench functions for the electron-capture nuclide and the tracer, the computation of the counting efficiency for 3H, the low-energy beta-ray emitter commonly used as tracer, is included in the program as an option. Program summary Title of program:EMILIA Catalogue identifier:ADWK Program summary URL: http://cpc.cs.qub.ac.uk/summaries/ADWK Program obtainable from: CPC Program Library, Queen's University of Belfast, N. Ireland Licensing previsions: none Computers: revisions: any IBM PC compatible with 80386 or higher Intel processors Operating systems under which the program has been tested:MS-DOS and higher systems Programming language used:FORTRAN 77 Memory required to execute with typical data: 253 kword No. of bits in a word: 32 No. of lines in distributed program, including test data, etc.:7147 No. of bytes in distributed program, including test data, etc.:74 776 Distribution format:tar.gz Nature of the physical problem: The determination of radioactivity in liquid samples of electron-capture nuclides is demanded in radiation physics, radiation protection, dosimetry, radiobiology and nuclear medicine. The CIEMAT/NIST method has proved to be suitable for radionuclide standardizations when the counting efficiency of the liquid-scintillation spectrometer is sufficiently high. Although the method has widely been applied to beta-ray nuclides, its applicability to electron-capture nuclides nowadays has not the required degree of accuracy. The inaccuracies of the method are mainly induced by the huge number of low-energy electrons and X-ray photons emitted by the atomic rearrangement cascade after the electron-capture process, which are efficiently detected by liquid-scintillation counting, but are of difficult modeling due to the inherent complexity of the atomic rearrangement process and the non-linear response of the spectrometer in the low-energy range. Solution method: A detailed simulation of the non-linear response of the spectrometer to photoionization must include the radiation emitted by the atomic rearrangement cascade. However, a model considering all possible scintillator de-excitations at atomic level increases exponentially the number of atomic rearrangement detection pathways subsequent to capture. Since the contribution of the non-linear effects to the counting efficiency are only corrective, we can approximate the reduced energy involved in the photoionization process to a sum of only three terms: the photoelectron energy, the mean energy of the KXY Auger electrons and the global energy contribution of the remaining radiation (electrons and X-rays) emitted by the atomic rearrangement cascade. The value of each term depends on the nature of the atom in which photoabsorption is produced and on the atom shell from where the photoelectron is ejected. The non-linear correction required to simulate low-energy X-ray photoabsorption is basically important when the scintillator cocktail contains elements of high atomic numbers. For heavy atoms, the K- and L-shell binding energies can be slightly less than the energy of the colliding photon. For such cases, the non-linear effects can play an important role. Restrictions on the complexity of the problem: The simulation of all possible detection pathways of atomic rearrangement that follow to photoionization complicates the problem unnecessary. To correct the non-linear effects we consider only significative photoelectric interactions with the K- and L-shells. Also we assume that K-shell photoionizations only generate three types of entities: the photoelectron itself, KXY Auger electrons and a radiation group that includes the remaining emitted particles. For L-shell photoelectrons the radiation emission subsequent to photoionization is considered as a whole.

Evaluation of S Values for Beta-ray Emitters within the Urinary Bladder

S values to the urinary bladder wall for several beta-ray emitters such as 14C, 24Na, 32P, ^Co, 89Sr, ^Sr, 90Y, 91Y, 137Cs, 147Pm and 204Tl have been evaluated using the Monte Carlo simulation. The S values evaluations were made on the Medical Internal Radiation Dose (MIRD) Committee of the Society of Nuclear Medicine Pamphlet No. 5 type phantoms (MIRD 5 type phantoms) and the Japanese adult voxel phantoms developed at the Japan Atomic Energy Research Institute (JAERI). It was found that the absorbed dose to the urinary bladder wall for those radionuclides are not one-half of the absorbed dose in the bladder contents and largely depend on the mass of the urinary bladder wall. The S values derived from the simple assumption that the dose at the surface of the contents is one-half of the dose within the contents were found to be conservative for the dose evaluation of beta-ray emitters within the urinary bladder.

Histomorphometric evaluation of (198)Au endovascular brachytherapy in a renal artery restenosis model in rabbits.

The main mid-term complication of percutaneous transluminal angioplasty of the renal artery is restenosis, which occurs in up to 50% of patients. Although no pharmacologic agent to date has been effective in preventing restenosis, both beta-ray emitters and gamma-ray emitters used in endovascular brachytherapy have been shown to reduce coronary restenosis. The objectives of this study were to evaluate the efficacy of (198)Au endovascular brachytherapy in preventing restenosis after percutaneous transluminal renal angioplasty and to determine the radiation dose to the operator. Twenty-one New Zealand white rabbits (10 females and 11 males) weighing an average of 3.5 kg (range, 3.2-3.8 kg) who had been fed a normal diet underwent bilateral 33% overdilatation with deendothelialization of the renal arteries. After 7 weeks, the induced renal artery stenoses were treated by percutaneous transluminal renal angioplasty. The rabbits were randomly assigned to one of three groups before receiving endovascular 25-Gy irradiation at a radial 2.0-mm depth with a 0.5 x 15 mm (198)Au wire (106 MBq). The right renal artery was irradiated in group A; the left, in group B. The rabbits in group C randomly received a right- or left-sided dummy wire. Operator exposure to radiation was measured using thermoluminescent dosimeters and ionization chambers. The rabbits were sacrificed after 3 weeks. The aorta and renal arteries were perfusion-fixed. The renal arteries were removed for histologic and histomorphometric study. Forty-two renal arteries were cut into a series of 4- micro m-thick slices. Five arteries were thrombosed (two in the irradiated group and three in the control group, p > 0.05). In the patent arteries (n = 37), the average neointimal area was 0.068 mm(2) (range, 0.009-0.234 mm(2)) in 15 irradiated segments (315 slices total), whereas the average neointimal area was 0.135 mm(2) (range, 0.016-0.324 mm(2)) in 22 control segments (462 slices total) (analysis of variance, p < 0.009), showing a percentage area of restenosis of 10.4% in irradiated arteries and 43.4% in non-irradiated arteries (p < 0.0003). Radiation dose per procedure to the operator was 0.034 mSv in the index finger, 0.024 mSv in the wrist, and undectable in the body. Endovascular brachytherapy with (198)Au appears to inhibit early renal artery restenosis and exposes the operator to a safe level of radiation.

Standardization of electron-capture radionuclides by liquid scintillation counting

Liquid scintillation counting has proven to be an excellent technique to standardize beta-ray emitters with good accuracy. However, the success achieved in beta-ray nuclide standardization is not extensible for radionuclides decaying by electron-capture. Last comparison of 55Fe revealed discrepancies of 5% among laboratories. This paper presents two new versions of the computer program EMI. First we consider a better simulation of the photoelectric interaction of X-rays with the scintillator cocktail (EMI 1.2); and second, a more sophisticated KL 1L 2L 3M atomic rearrangement model (EMI 2.0). We emphasize the importance of improving the simulation of the electron capture process to achieve better standardization of electron-capture nuclides by the CIEMAT/NIST method.

Simulation of the Energetic and Angular Response of a CaSO4:Dy Dosemeter to Weakly Penetrating Beta Radiation Using the EGS4 Transport Code

CaSO 4 :Dy is a good thermoluminescent TL material for personal dosimetry because of its high sensitivity, although it is not tissue-equivalent. A dosemeter based on this TL material has been developed for weakly penetrating beta radiation. The dosemeter consists of a detector, composed of a 60 mg,cm -2 thick layer of CaSO 4 :Dy (0.1%) pressed on an aluminium foil (84 mg.cm -1 thick and 7 mm diameter), covered by a 5 mg,cm -2 thick polyethylene filter. The EGS4 code has been used for Monte Carlo simulation to estimate the dosemeter response. Experimental and calculated results of the energy and angular responses to beta radiation, corresponding to beta ray emitters of the secondary standard (ISO 6980) 90 Sr/ 90 MY, 204 TI and 147 12m, are presented.

Standardization of beta and electron-capture nuclides in liquid scintillation gel samples

Gels permit one to save much work in liquid scintillation sample preparations. However, the presence of large amounts of water reduces the counting efficiency, which makes its determination more difficult. Experiment shows that standardization curves, efficiency as a function of quenching, are not affected by the water content, when the nuclide is a pure beta-ray emitter. However, some electron-capture nuclides have standardization curves which depend significantly on the volumes of water incorporated to the sample. This article studies the conditions for a direct standardization of beta and electron-capture nuclides in gel samples with water loading of up to 33% by volume.

Radioactivity determination of 90Y, 90Sr and 89Sr mixtures by spectral deconvolution

The measurement of 90Y, 90Sr and 89Sr in environmental samples has received considerable attention since the advent of the nuclear era. These three radionuclides are pure beta-ray emitters and a nondestructive sample analysis procedure is not available. It is necessary to use complex radiochemical separation procedures to isolate these radionuclides prior to counting. The result is a significant delay between the sample treatment and the activity determination. A rapid analytical procedure is required to obtain the activity of these radionuclides and would appear to be an important goal. A deconvolution method has been applied to logarithmic spectra obtained with a liquid scintillation spectrometer. In a previous paper, this procedure was applied to samples in which 90Y and 90Sr were in equilibrium. Samples have been assessed in which 90Y activity was higher or lower than 90Sr activity, and medium and low activities were considered. Samples with count rates below ba-ckground were analyzed, and the limits of detection of the procedure were determined. The effects of chemical quench and the different activity ratios were studied. It was shown that this treatment of the beta spectra is adequate and represents a rapid method of determining these radionuclides.

Spectrum unfolding and double window methods applied to standardization of 14C and 3H mixtures

A spectrum unfolding method for beta-ray emitters is applied to double-label counting of 3H and 14C. Twenty-two samples with counting rate rati

Reconstructive bremsstrahlung tomography as a method of imaging pure beta-ray emitters in matter

The detection of pure β-ray emitters deep within matter is made difficult by the short β particle range. This difficulty may be overcome by detecting the bremsstrahlung emitted from the source and its surrounding material. The principle of reconstructive emission tomography has been applied to the bremsstrahlung in order to form an image of a source of 32P within a water filled container. Some problems associated with the technique are briefly discussed.

A random interval generator using beta ray emission

A solid generator of random intervals, based on a beta ray emitter, is described. The instrument provides for independent control of the minimal interval between successive output plus and of the dispersion of the random intervals. It has been used for delivering sensory stimuli at random intervals or in random sequences.