Thyroid-Gland Irradiation Dose in the Russian Population Due to the Fallout of Radioactive Iodine After the Chernobyl Accident

The average irradiation dose to the thyroid gland is estimated for the people living in 4105 populated points in the Bryanskaya, Tul'skaya, Orlovskaya, and Kaluzhskaya oblasts. The basic principles of the method used to reconstruct the dose are presented. The people living in Bryanskaya oblast have the highest irradiation dose to the thyroid gland: in children less than 3 yr old the individual dose reached 10 Gy; the average dose exceeded 2.5 Gy in 12 populated points. In children living in Bryanskaya oblast, for populated points with soil contamination density above 37 kBq/m² the irradiation dose exceeded 0.05 Gy. The highest average irradiation dose to the thyroid gland in children living in Tul'skaya, Orlovskaya, and Kaluzhskaya oblasts is 0.3–1 Gy. The collective irradiation dose for the four most strongly contaminated oblasts is estimated to be as follows: Bryanskaya – 60, Tul'skaya – 20, Orlovskaya – 13, Kaluzhskaya – 3.5 thousand·people·Gy.     

Internal irradiation of the thyroid gland in residents of Kaluga Oblast from results of <Superscript>131</Superscript>I content measurements performed in May 1986

The content of ¹³¹I in the thyroid gland of approximately 30000 residents of Kaluga oblast was measured in May 1986. The work was supported by calibration and verification of the measurement means and procedure. The data making it possible to evaluate the individual, average, median, and collective dose of internal irradiation of the thyroid gland in people of different ages in the populated points of the oblast are presented. The irradiation dose to the thyroid gland in children is much higher than for adults. It is found that the individual dose of internal irradiation to the thyroid gland is described by a nearly log-normal distribution. Some of the individuals examined have an individual dose which is several-fold higher than the average and median dose. This indicates the presence of groups with an elevated radiation risk; attention should be focused on this group first when medical-prophylactic and protective measures are taken. The data from Kaluga oblast, combined with similar results from Bryansk oblast and Belarus, have served as basis for reconstructing the individual absorbed irradiation dose to the thyroid gland and as dosimetric support of radiation-epidemiological studies using the case-monitoring procedure. Translated from Atomnaya énergiya, Vol. 105, No. 2, pp. 97–103, August, 2008.     

Experimental setup for studying the effects of alpha particles on zebrafish embryos

In the present work, we have studied the feasibility to use an experimental setup based on polyallyldiglycol-carbonate (PADC) films to study effects of alpha particles on dechorionated zebrafish embryos. Thin PADC films with a thickness of 16 μm were prepared from commercially available CR-39 films by chemical etching and used as support substrates for holding zebrafish embryos for alpha-particle irradiation. These films recorded alpha-particle hit positions, quantified the number and energy of alpha particles actually incident on the embryo cells, and thus enabled the calculation of the dose absorbed by the embryo cells. Irradiation was made at 4 h post fertilization (hpf) with absorbed doses up to 2.3 mGy. Images of the embryos at 48 hpf were examined for identification of morphologic abnormalities. The preliminary results showed that absorbed doses corresponding to the abnormally developed embryos ranged from 0.41 to 2.3 mGy, which was equivalent to 0.21-1.2 mGy in human.     

32P Accumulation in Fish in the Enisei River and Reconstruction of the Irradiation Dose to the Public

The results of experimental and theoretical investigations of the behavior in the Enisei River of ³²P entering the river for more than 30 yr with discharges from the Krasnoyarsk Integrated Mining–Chemical Plant are presented. It is shown that ³²P is accumulated actively by water organisms. Its concentration in fish is a thousand times higher than in water. The ³²P content in fish depends little on the type of food ingested by the fish but depends strongly on season, reaching its maximum value in August. A model of the dynamics of the ³²P contamination of fish in the Enisei River over a 25-yr period of operation of the plant (1975–2000) is constructed and verified. The computational estimates show that the irradiation dose due to ³²P to the critical group of the population living in the near zone (fishermen and members of their families) was 0.4–1.6 mSv/yr in 1975–1992 (the maximum value occurred in 1977 and the minimum value occurred in 1992). For the rural population which was not part of the critical group, the irradiation dose from ³²P during the same years was in the range 0.14–0.5 mSv/yr.     

Effective dose of internal irradiation for residents of the most contaminated areas of Bryansk and Kaluga oblasts

Measurements of the ^134,137Cs content in the bodies of the residents of the most contaminated areas of Bryansk and Kaluga oblasts have been performed since 1986. Data which make it possible to evaluate the individual and average effective dose of internal irradiation have been obtained. The work has been supported by calibration and verification of the measurement means and methods. It has been established that the individual dose is described by a nearly log-normal distribution with a long “tail” at doses substantially above the average and median values. This indicates the existence of groups with an elevated radiation risk so that these groups should be treated first when preventative-medical and protective measures are taken. It is shown that for the most highly contaminated regions of Bryansk and Kaluga oblasts most of the effective dose of internal irradiation is formed over a period of 8–10 years after the accident. __________ Translated from Atomnaya énergiya, Vol. 103, No. 3, pp. 192–197, September, 2007.     

Irradiation dose for personnel during brachytherapy of malignant neoplasms with 32P microsources

Experimental measurements of the local absorbed radiation dose in the most irradiated parts of the bodies of personnel (the skin of the hands and palms, eyes, thorax, and abdomen of operators) by means of high sensitivity TLD-500K thermoluminescence detectors are reported. It is found that, for ³²P microsources with a total activity of 100 MBq, after 6 hours of work without protective x-ray gloves during a simulation of placing a real preparation in the region of the liver of an adult phantom, the maximum local irradiation dose to the hands (the skin of the left middle finger and thumb) from bremsstrahlung with deduction of the natural background and without special protective measures is 0.54 ± 0.001 mGy, the minimum dose (skin on the palm of the right hand) is 0.1 ± 0.01 mGy, and the irradiation of the thorax, abdomen, and eyes of the operator is less than 0.12 mGy. This presents no radiation hazard, even for repeated work with these sources. Translated from Atomnaya énergiya, Vol. 105, No. 4, pp. 233–235, October, 2008.     

The EPR: A clear step forward in dose reduction and radiation protection

For the European Pressurized Water Reactor (EPR) a large effort was made to improve the plant design with respect to radiation protection using the experience gained during the design of former generations of pressurized water reactor (PWR) in France and Germany, and their current operation. Keeping the radiation exposure of personnel to an acceptable level is one of the main objectives of the EPR design. Both the individual and the collective doses are considered.Internationally comparable limits based on recommendations of the International Commission on Radiological Protection (ICRP) have been established for individual doses. These limits describe the framework within which the individual dose shall be kept as low as possible, applying the principles:

• Justification: No practice involving exposures to radiation should be adopted unless it produces sufficient benefit to the exposed individuals or to society to offset the radiation detriment it causes.

• Optimization: In relation to any particular source within a practice, the magnitude of individual doses, the number of people exposed, and the likelihood of incurring exposures where these are not certain to be received should all be kept as low as reasonably achievable (ALARA), economic and social factors being taken into account.

• Limitation: The exposure of individuals resulting from the combination of all the relevant practices is subject to dose limits.

The paper describes the design provision and measures introduced in the plant design to achieve the above described goals.They are in essence:

• measures to avoid or to reduce sources of radiation;

• layout aspects;

• provisions made in the component design with respect to ease of operation and maintenance management;

• improved possibilities of decontamination;

• use of operating experience for design improvements.

The radiation protection layout principles compiled on the basis of safe operating experience gained from the existing pressurized water reactors in France and Germany are used to develop an improved plant design with respect to radiation protection aspects and dose optimization.Summary: The European Pressurized Water Reactor is an evolutionary third-generation pressurized water reactor with a rating in the 1600 MWe class. Its development was started in 1992 by Framatome and Siemens, whose nuclear activities were combined in January 2001 to form Framatome ANP, now AREVA NP. Being the product of intense bilateral cooperation the EPR combines the technological accomplishments of the world's two leading PWR product lines—the French N4 reactors in operation at Chooz and Civeaux and the Konvoi reactors in operation at Neckarwestheim, Emsland and Isar in Germany. From the very start, development of the EPR was focused on improving plant safety and economics even further and also a large effort was made to improve the plant design with respect to radiation protection. Keeping the doses received by operating and maintenance personnel to a level far below the limiting values was one of the main objectives of the EPR design. Both the individual and the collective doses are considered in this article.     

Passage of neutrons through narrow gaps in the blanket and shielding of a thermonuclear reactor

Conclusions Straight, through cracks in the blanket and shielding of a thermonuclear reactor even with a width of about 5 mm lead to a significant local increase in the fluence of fast and intermediate neutrons in the region of the magnetic coils of the toroidal field. In spite of the sharp drop in the fluxes of 14-MeV neutrons away from the axis, the region where the gap has an appreciable effect is large and equals 5–15 cm, depending on the gap width.The use of a stepped gap significantly increases the efficiency of the shielding when the axes of the gaps are dipslaceed by a distance greater than two gap widths. For smaller displacements the effect of the gaps is appreciable, which sharply reduces the efficiency of the shielding. Even with displacements exceeding two gap widths, however, the coefficient of variation of the fluence of 14-MeV neutrons is large and equals 3–7 for gap widths ranging from 0.5 to 1 cm.Preliminary calculations show that over a period of five years of operation of a test thermonuclear reactor with a neutron load of 1 MW/m² on the first wall the dose absorbed in the layer of insulation of the magnetic coils of the toroidal field, which is adjacent to the cryostat, can reach (5–6)·10⁹ rad, and the number of displacements in the copper stabilizing conductor can reach (1–5)·10^–4 per atom. These values fall at the limit of admissibility, and for this reason even a local increase in the values owing to the gap could be critical. To make a more accurate evaluation of the effect the construction of the blanket and the magnetic coils of the test thermonuclear reactor as well as the criteria adopted for the efficiency of the shielding of the thermonuclear reactor must be specified more accurately.Translated from Atomnaya Énergiya, Vol. 65, pp. 339–343, November, 1988     

Method for measuring the radiation-induced electrical conductivity in ferroelectrics with pulsed irradiation

Conclusions Under the assumptions that the volume and surface RIE are power-law functions of the dose rate and Ohm's law is valid for the FE with irradiation, and equation was derived for the leakage current owing to RIE and the electric field generated by the pyroelectric effect in the FE. In this case the parameters characterizing the RIE can, be found by solving a system of four equations, which are constructed based on experimental results for samples of material with different dimensions. In practice the number of unknown can be reduced by using specially constructed samples of the materials (this work) or radiation collimators, which enables irradiation of the required region of the sample.The experimental results obtained with PKR-7M piezoelectric ceramic showed that for dose rates (0.25–5.2)·10⁷ Gy·sec^–1 [the corresponding dose range is (0.19–3.6)×10³ Gy] both the volume and surface RIE can be represented by a linear function of the dose rate with proportionality coefficients k_v=1.2·10^{–11 –1}·m^–1·Gy^–1·sec and k_s=0.53·10^{–11 –1}·Gy^–1·sec.The upper limit of the residual RIE of PKR-7M with a maximum dose rate per pulse of 5.2·10⁷ Gy·sec^–1 equals =10^{10–6 –1}·m^–1.Translated from Atomnaya Énergiya, Vol. 63, No. 4, pp. 261–264, October, 1987.     

The effect of radiation on the properties of silicone rubber

As a result of -radiation, silicone rubber undergoes a series of changes due to radiation cross-linking. The modulus of elasticity increases linearily with a dose up to 150–200 megarads. The vitrification temperature (– 120 to- 125 ° C) hardly changes up to 100 megarads and at 270 megarads it is –110 to –115 ° C. With cross-linking, the rate of crystallization and degree of crystallinity decrease. The melting point falls from – 35 ° C for the initial material to – 55 ° C for rubber Irradiated with a dose of 40 megarads. A dose of 100 megarads practically completely eliminates crystallization. This dose produces rigid rubbers with a modulus of 200– 250 kg/cm² and a high degree of frost resistance, (Tg –125 ° C), but with a very small breaking stretch (15–20%) with a strength of 30–40 kg/cm².     

Heterogeneous Transmutation of Am, Cm, and Np in a BREST Core

The effect of heterogeneous (in individual units) transmutation of Am, Cm, and Np on the radiation characteristics of fuel is examined. For heterogeneous transmutation of Am, Cm, and Np in individual fuel elements containing nitrides, the radiation characteristics and energy release increase substantially compared with fresh homogeneous fuel elements. Heterogeneous transmutation is dangerous from the standpoint of nonproliferation of fissioning materials because of the low critical mass of the main nuclides – ²³⁹Np and americium isotopes. 2 tables, 4 references.     

Individual Injection, Cooling, and Accumulation of Rare Radioactive Ions

A scheme for accumulating radioactive ions, which is geared toward a quasicontinuous low-intensity flux, is discussed. It is based on individual correction of the trajectory and momentum deflection of each ion in the transport channel and individual ion injection into the accumulator ring. The advantages of this scheme are low accumulator acceptance 5–10 ·mm·mrad, high ion accumulation rate – up to 10³ sec^–1 – with beam intensity after the fragment separator 10³–10⁴ sec^–1, and a 10⁴–10⁵-fold decrease of the pulse intensity of the primary beam on the productive target.     

Radiation Resistance of Fused Titanium Ceramic for Actinide Immobilization

The radiation resistance of ceramics proposed for solidification of actinide-containing wastes is studied. Their main concentrators (for uranium) in the samples are phases with fluorite type structure (zirconolite, pyrochlore, murataite), and brannerite. The critical dose for the transition of the crystal lattice of these phases into an amorphous state under irradiation with 1 MeV Kr⁺ at room temperature was 3·10¹⁸ m^–2 for zirconolite, (1.8–2.4)·10¹⁸ m^–2 for pyrochlore, (1.7–1.9)·10¹⁸ m^–2 for murataite, and 1.4·10¹⁸ m^–2 for brannerite. The forms of murataite with 3-, 5-, and 8-fold motif of the fluorite cell all have close radiation resistance. These data make it possible to estimate the transition time of the murataite structure into the amorphous state to be 6–7 hundred yr and 6–7 thousand yr with hypothetical content of ²³⁹Pu in it of 10% and 1%, respectively. The same values of the radiation resistance were obtained previously for titanates with pyrochlore structure, which were proposed by American researchers as matrices for immobilization of excess weapons plutonium.     

Determination of the235U concentration in the aqueous coolant of the first circuit of a nuclear reactor

Conclusions A technique was developed for determining the²³⁵U concentration in the aqueous coolant of the first circuit of a nuclear reactor: detection limit 3·10^–12 g/cm³. Using the method in the IVV-2M reactor has shown that with this technique, an operational monitoring of the uranium concentration in the coolant and in the fluids washed from the surface of the first circuit, as well as monitoring other qqueous samples, is possible.Lavsan, which is directly irradiated in a liquid sample and electrochemically etched, can be recommended as a detector. The optimal conditions of etching 180-m-thick lavsan (after irradiation with thermal neutrons to a flux of (1–2)·10¹⁶ cm^–2) are: 30% aqueous KOH solution, a temperature of (70±0.2)°C, an electric field strength of 20 kV/cm, a frequency of 4 kHz, and an etching time of 100 min.Translated from Atomnaya Énergiya, Vol. 61, No. 5, pp. 334–338, November, 1986.     

~(60)Co γ射线水吸收剂量量值传递方法初步研究

60Co γ射线水吸收剂量是放射治疗体系的基础物理量,在辐射治疗中发挥着重要作用。开展60 Coγ射线水吸收剂量值传递方法研究,可为我国γ射线水吸收剂量量值体系的建立提供重要技术支持。以PTW-30013电离室、PMMA水箱及三维移动平台为基础,建立量值传递标准装置;结合IAEATRS398报告的要求开展60 Coγ射线水吸收剂量量值传递方法的初步研究。经量值传递后,PTW-30013电离室60 Coγ射线水吸收剂量校准因子的扩展不确定度为0.90%(k=2),辐射计量中心(IAEA次级标准计量实验室)60 Co参考辐射γ射线水吸收剂量的扩展不确定度为1.4%(k=2)。结果表明,该量值传递方法可有效降低次级标准剂量实验室60 Coγ射线水吸收剂量的测量不确定度。     

Edge Effect in Coolant Radiolysis in a VVÉR Core

Calculations are performed of the concentration of oxidizers of radiolytic origin (O₂, H₂O₂, and O₂ ^–) in a VVÉR first loop with hydrogen water chemistry and a different temporal dropoff law for the absorbed dose rate in the coolant at the core exit. It is shown that a linear or exponential dropoff of the dose rate on the segment of the first loop corresponding to a coolant residence time of 0.1 sec results in a lower concentration of radiolytic oxygen and hydrogen peroxide in the first loop outside the core by at least a factor of 10. 3 figures, 10 references.     

Results of the experimental campaign on contaminated metal components parameters and suggestions for safely NPP component dismantling

This paper concerns the dismantling activities of Caorso NPP (BWR, Boiling Water Reactor, 870 MWe, built in the 70s and fully operating in the period 1981–1986). The said plant was shut down on 1987, following Italy's poll that abrogated nuclear power use based on U235 fission. The considered activities involved an experimental campaign using plasma torch and oxyacetylene arc metal cutting processes, and regarding no radioactive materials–pipes and plates exposed to the reactor coolant steam.The performed analyses of by use contaminated components below the free release level (1 × 10⁴ Bq/m²), not yet considering radioactivity, allowed an accurate estimation of the chemical and physical characteristics of the produced aerosol.The adopted operative conditions concerning the cut procedures are firstly described. The emissions composition and technical parameters such as cutting time and cutting rate vs. pipe diameter or plate thickness are reported. The results highlight the kind of trouble that can emerge in the cutting processes, in particular focusing on a comparison of the effects of the two cutting processes and the chemical composition of dusts collected by filtering the gaseous emission. The achievable chances connected to the adopted filtration methods are then revealed, and the obtained parameters related with the production of volatile and solid residuals for cut are reported. Some suggestions follow, finally, for a safely NPP components disassembling.     

Study of a spent fuel element from the first atomic electric station

This communication gives information on the study of a fuel element of the First atomic electric station which had been exposed in the reactor for 445 effective 24-hour periods. Diameter measurements show that there is a limit to fuel elements swelling at large burnouts. The concentration of transuranic elements in fuel element is equal to (in kilograms per ton of uranium): Pu²³⁹–4.10, Pu²⁴⁰–1.53, Pu²⁴¹–0.64, Pu²⁴²–0.20, Cm²⁴²–2.73·10^–3.     

Gamma and neutron dosimetry in nuclear reactors by means of colored polyvinyl alcohol films

It is shown that polyvinyl alcohol films containing methylene blue which become discolored under the effects of radiation are suitable for gamma and neutron radiation dosimetry in nuclear reactors. The degree of discoloration varies linearly with the dose in the 10⁴–10⁶ rad range and, over a broad range of values, is practically independent of variations in linear energy transfer, dose rate, and temperature. Films containing boric acid in addition to the dye can be used for recording thermal-neutron doses in the 10¹²–10¹⁴ neutrons/cm² range. The measurement error is within ±10% in every case.Translated from Atomnaya Énergiya, Vol. 19, No. 3, pp. 273–276, September, 1965.     

Reaction kinetics and the equilibrium state in the system CO2-CO-C under the action of fast electrons

The kinetics of reactions occurring in the system CO₂–CO–C under the action of fast electrons (200 keV) were studied under standard conditions. The temperature was varied within the range 25–400° C; pressure 200–600 mm Hg. The absorbed energy was equal to 3.0·10¹⁵ eV/(cm³· sec) at a current strength of 100 A. The decomposition of CO₂ in the presence of carbon is a zero order reaction, while the decomposition of CO is a first order reaction. The activation energies of both reactions are close to zero. The rate of decomposition of CO₂ and CO is a linear function of the radiation intensity. The steady-state concentration of CO, established in the system after prolonged irradiation, is independent of the radiation intensity, temperature of the reaction zone, and depends on the magnitude of the carbon surface.Translated from Atomnaya Énergiya, Vol. 18, No. 5, pp. 492–496, May, 1965