Hydrogen production in gamma radiolysis of the mixture of mordenite and seawater

Hydrogen production by γ-radiolysis of the mixture of mordenite, a zeolite mineral, and seawater was studied in order to provide basic points of view for the influences of zeolite minerals, of the salts in seawater, and of rise in temperature on the hydrogen production by the radiolysis of water. These influences are required to be considered in the evaluation of the hydrogen production from residual water in the waste zeolite adsorbents generated in Fukushima Dai-ichi Nuclear Power Station. As the influence of the mordenite, an additional production of hydrogen besides the hydrogen production by the radiolysis of water was observed. The additional hydrogen can be interpreted as the hydrogen production induced by the absorbed energy of the mordenite at the yield of 2.3×10^?8 mol/J. The influence of the salts was observed as increase of the hydrogen production. The influence of the salts can be attributed to the reactions of bromide and chloride ions inhibiting the reaction of hydrogen with hydroxyl radical. The influence of the rise in temperature was not significantly observed up to 60°C in the mixture with seawater. The results show that the additional production of hydrogen due to the mordenite had little temperature dependence.     

Simulation study of personal dose equivalent for external exposure to radioactive cesium distributed in soil

The personal dose equivalent was calculated for the public (newborns; 1-, 5-, 10-, and 15-year-old children; and adults) in an environment contaminated with radioactive cesium (¹³⁴Cs and ¹³⁷Cs) distributed in a soil at specific depths of 0.0, 0.5, 2.5, 5.0, 10.0, and 50.0 g/cm², and the conversion coefficients for converting activity concentration to personal dose equivalent rate were provided for each age group. Monte Carlo calculations were performed using pediatric and adult computational phantoms incorporated into a particle and heavy ion transport code system. Compared with the effective dose and ambient dose equivalent at a height of 100 cm above the ground, the personal dose equivalent was found to provide a good estimate as a measurable quantity for the effective dose and did not exceed the ambient dose equivalent even in the environmental radiation fields, while the personal dose equivalent values increased for younger subjects. The weighted-integral method to obtain the personal dose equivalent for a volumetric source was applied to the analysis of exponential radioactive cesium distributions in the soil observed in Fukushima, and the calculation results successfully reproduced the measured data.     

肿瘤介入治疗源剂量分布的 Monte Carlo模拟与分析

应用Monte Carlo方法计算了介入治疗源的剂量场分布,模拟了粒子在生物组织中的输运过程,研究了^125Ⅰ辐射源的几何特性以及介质的均匀性,分析了这些因素对剂量分布的影响。     

Study of radiation dose reduction of buildings of different sizes and materials

The dependence of radiation dose reduction on the sizes and materials of buildings was studied by numerical analyses using the Monte Carlo simulation code, PHITS. The dose rates inside the buildings were calculated by simulating gamma-ray transport from radioactive cesium deposited at the ground surface. Three building models were developed: the wooden house, the open-space concrete building, and the thin-wall building, to study the effect of building size and construction material on dose reduction inside these structures. Here the floor-area sizes of the building models were varied to clarify the influence of building configuration on dose reduction. The results demonstrated that the dose rates inside the buildings linearly decreased with increasing floor area on a logarithmic scale for all types of buildings considered. The calculated dose distribution inside a building indicated that the distance from the outer walls was a determining factor for the dose rate at each position in the building. The obtained tendency was verified by comparison with data reflecting the dose reduction of typical buildings in Japan.     

Development of an effective dose calculation method for the downstairs room of a linac facility

ABSTRACT

An effective dose calculation method is important in the design of efficient shields in radiation facilities. Some analytical methods have been shown to provide a simple and quick design analysis; however, no suitable method exists that can be applied to a room located directly under an X-ray irradiation room. We propose a new analytical method that uses the multiple reflection ratio predetermined by a Monte Carlo simulation and the differential dose albedo given by the Chilton–Huddleston semi-empirical equation. Our method is verified by comparison with the Monte Carlo simulation, performed for the case of an electron linac facility with an accelerated energy of 10 MeV, where the shielding floor has a thickness of 1.6–2.0 m and the downstairs room has a height of 0.5–1.5 m. The difference between the effective X-ray doses in the downstairs room calculated via the proposed analytical method and the Monte Carlo simulation is less than 25% when the horizontal distance from the X-ray beam to the evaluation point exceeds 3 m and the evaluation point is set at half of the height of the room. The new analytical method can be efficiently and accurately applied to the calculation of the effective dose.     

几种半导体器件的硬X射线剂量增强效应研究

本文给出了大规模集成电路CMOS4069、浮栅ROM器件在北京同步辐射装置（BSRF）和钴源辐照的X射线剂量增强效应实验结果。通过实验在线测得CMOS4069阈值电压漂移随总剂量的变化，测得28f256、29c256位错误数随总剂量的变化，给出相同累积剂量时X光辐照和γ射线辐照的总剂量效应损伤等效关系。这些结果对器件抗X射线辐射加固技术研究有重要价值。     

Radiation effects in Be and Al for a magnetic fusion production reactor

Estimates of the expected performance of beryllium and several aluminum alloy structural components of the breeding blanket of a magnetic fusion production reactor are made based on the known behavior and properties of these materials in fission reactor applications. Comparisons of the irradiation damage effects resulting from the fission reactor neutron spectra and the fusion reactor blanket spectra indicate that beryllium will perform well in the breeding blanket for at least one year and the aluminum alloy 5052 will retain structural integrity for about 5 years.This paper represents work carried out from 1980 to 1982 and was in draft form in 1982. It was received for publication with only minor editing of its 1982 version, explaining the fact that some of the material is dated.     

双极晶体管瞬态辐射光电流分流补偿法及其实验研究

采用标准分立双极元件,对双极晶体管瞬态辐射光电流分流补偿法进行了实验验证。给出了双极晶体管瞬态辐射响应及光电流分流补偿原理,比较了带补偿与不带补偿电路的瞬态响应波形。实验结果对双极晶体管集成电路瞬态辐射加固具有指导意义。     

废树脂热态压实废物包自辐照产气的初步计算分析

本文通过Microsheild软件和文献报道的气体辐射化学产额(G值),采用偏保守参数和模型计算了废树脂热态压实废物包的吸收剂量以及产气量.结果表明,废物包约100年后的吸收剂量趋于稳定,预期和最大累积吸收剂量分别约为3.6×105 Gy和1.4×106 Gy,累积压力分别约为1.0×106 Pa和2.5×106 Pa...     

Primary yields and reaction sets with corresponding rate constants for computer simulation of water radiolysis at elevated temperature

The chemical conditions of coolant water in light water reactors are important factors affecting the corrosive environment and the integrity of the structural materials. Computer simulations have commonly been used to predict chemical environment changes due to water radiolysis under extreme conditions. Initial parameters, including the chemical reactions, rate constants, and primary yields of water decomposition by radiolysis, have been reported by several groups in the past few decades. Using a FACSIMILE simulation, the variations caused by utilizing different sets of primary yields of water radiolysis, including γ-rays and fast neutrons, along with the chemical reactions and rate constants at 285 °C were evaluated in this study. The rate constant of the reverse reaction of OH + H₂ → H + H₂O was found to be the main factor controlling the variation between the different sets of chemical reactions and rate constants.     

Development of radiation-resistant optical fiber for application to observation and laser spectroscopy under high radiation dose

In the Fukushima Daiichi Nuclear Power Station, it is necessary to survey the locations and conditions of fuel debris inside reactor pressure vessels or primary containment vessels under water and radiation environment in preparation for removing fuel debris. An optical fiber is well known for features such as signal transmission, light weight, superior insulation performance, water resistance and electromagnetic noise resistance. These features allow the optical fiber to simplify the instrumentation systems for in-vessel inspection, as long as provide that the optical fiber can be used under high radiation dose environment. The radiation resistance of an optical fiber was improved by increasing the amount of hydroxyl up to 1000 ppm in pure silica fiber. The improved optical fibers were irradiated with γ-ray up to 1 × 10⁶ Gy using a ⁶⁰Co source. They indicated a large peak around 600 nm and a peak tail from ultraviolet region, but no large absorption in infrared region except a hydroxyl absorption peak of 945 nm. We have confirmed that the optical fiber containing 1000 ppm hydroxyl has enough radiation resistance for radiation-induced transmission losses, and the infrared imaging is effective for observation under high radiation doses.     

核事故应急情况下快速确定辐射剂量率场的方法及其应用

介绍并分析了在核事故应急情况下,应急辐射监测和事故后果评价两种确定辐射剂量率场的方法及存在的不足,根据估算照射率场分布的方法引出快速估算辐射剂量率场的计算方法,并对其在事故应急和演习中的应用进行了分析。     

The effects of low dose rate irradiation and thermal aging on reactor structural alloys

As part of the EBR-II reactor materials surveillance program, test samples of fifteen different alloys were placed into EBR-II in 1965. The surveillance (SURV) program was intended to determine property changes in reactor structural materials caused by irradiation and thermal aging. In this work, the effect of low dose rate (approximately 2 × 10⁻⁸ dpa/s) irradiation at 380–410°C and long term thermal aging at 371°C on the properties of 20% cold worked 304 stainless steel, 420 stainless steel, Inconel X750, 304/308 stainless weld material, and 17-4 PH steel are evaluated. Doses of up to 6.8 dpa and thermal aging to 2994 days did not significantly affect the density of these alloys. The strength of 304 SS, X750, 17-4 PH, and 304/308 weld material increased with irradiation. In contrast, the strength of 420 stainless steel decreased with irradiation. Irradiation decreased the impact energy in both Inconel X750 and 17-4 PH steel. Thermal aging decreased the impact energy in 17-4 PH steel and increased the impact energy in Inconel X750. Tensile property comparisons of 304 SURV samples with 304 samples irradiated in EBR-II at a higher dose rate show that the higher dose rate samples had greater increases in strength and greater losses in ductility.     

The effects of heating rate on the dose response characteristics of TLD-200, TLD-300 and TLD-400

In the given study; the effects of heating rates on the dose response characteristics of CaF₂:Dy (TLD-200), CaF₂:Tm (TLD-300) and CaF₂:Mn (TLD-400) crystals have been investigated using the dose dependence curve and dose response function f(D). It was observed from the dose response functions that the linearity and behaviour of the TL glow peaks of TLD-200 and TLD-400 are affected, but the TLD-300 is not affected from the heating rate.     

氢-水同位素交换分离因子理论计算

采用量子化学从头计算法计算得到氢水同位素交换体系HDg／H2O1和DTg／D2O1在O．1MPa、283．2～373．2K下的气相反应平衡常数，并根据相应同位素水的饱和蒸气压求得气液交换过程的分离因子，得出了两种氢水同位素交换体系总反应分离因子。     

Effects of hydrazine addition and N2 atmosphere on the corrosion of reactor vessel steels in diluted seawater under gamma-rays irradiation

Seawater was injected into the reactor cores in the Fukushima Daiichi Nuclear Power Station. Corrosion of primary containment vessel (PCV) steel and reactor pressure vessel (RPV) steel is considered to progress until the molten fuel debris is removed. To evaluate durability of the PCV and RPV steels, corrosion tests were conducted in diluted seawater at 50 °C under gamma-rays irradiation of dose rates of 4.4 and 0.2 kGy/h. To evaluate the effect of hydrazine (N₂H₄) as an oxygen scavenger under gamma-rays irradiation, 10 and 100 mg/L N₂H₄ were added to the diluted seawater. Without addition of N₂H₄, weight loss in the PCV and RPV steels irradiated with the 0.2 kGy/h dose rate was comparable with those without irradiation and weight loss in the vessel steels irradiated with the 4.4 kGy/h dose rate was higher than those without irradiation. Under irradiation, weight loss in the PCV and RPV steels in diluted seawater containing N₂H₄ was comparable with that in diluted seawater without N₂H₄. When gas phase in the flask was replaced with N₂, weight loss in the PCV and RPV steels, and O₂ and H₂O₂ concentrations in the diluted seawater decreased.     

Radiobioassay performance evaluation of urine and faeces samples for radiation emergency preparedness

In the event of a radiation emergency, it is necessary to assess intake and radiation dose for the internally contaminated casualties. This paper provides relatively rapid and simple procedures of bioassay. Faeces samples were ashed to improve sample homogeneity. Gamma spectrometry was used for radioactivity measurement. The measured results, including activity of the biosamples and associated uncertainty, were evaluated for traceability based on ANSI N42.22 and bias and precision based on ANIS/HPS N13.30. For all urine customary exercise samples, measurement results of ⁶⁰Co and ¹³⁷Cs were in good agreement with NIST values within 5% and satisfied ANSI N42.22 and ANIS/HPS N13.30 acceptance criteria. In contrast, the uncertainty of ⁵⁷Co was quite large and the activity differed from the NIST value by 18%. For the urine emergency preparedness exercise, all measured results agreed well with NIST values, with less than 10% difference. Synthetic faeces samples included ⁵⁴Mn, ⁶⁰Co, and ¹³⁴Cs. The activity of ⁶⁰Co was different from the NIST value by 9%, whereas the results for ⁵⁴Mn and ¹³⁴Cs were within 3.2%. The measurement procedures given in this study can be applied to assess intake of radionuclides and resulting radiation dose to casualties.     

反应堆退役三维辐射场实时计算及可视化

本文基于DELMIA和VIRTOOLS平台开发的反应堆退役三维仿真原型系统,提出了仿真系统、数据库和计算内核既相互独立又集成统一的三维辐射场计算和可视化技术方案。利用点核积分算法建立了三维辐射场计算模型,得到了能量的对数与转换系数的多项式拟合公式,考虑了设备屏蔽和自吸收效应。采用VS语言和SQL server软件平台编制了三维辐射场计算程序,经验证,在关键点处的辐射水平计算值与测量值的比值小于10,并嵌入了仿真系统,实现了退役场景三维辐射场的实时计算和数据更新。提出了基于行走路径的人员受照剂量计算方法,并实现了可视化显示。     

Effects of dose rate change under irradiation on hardening and microstructural evolution in A533B steel

Iron-ion irradiations were carried out for 0.09wt%Cu A533B steel specimens at 290°C to investigate effects of dose rate change during irradiation; the irradiations consisted of the base irradiation (with an unchanged dose rate) and an additional one with changed dose rates from 1 to 50 times that of the base one. Nano-indentation hardness measurements showed that the increase in hardness was higher for lower dose rate of the base irradiation. A similar trend was identified during the additional irradiation. Transmission electron microscope (TEM) and three-dimensional atom probe (3DAP) analyses were carried out for the quantitative characterization of defect features. Mn/Ni/Si/Cu-enriched clusters and dislocation loops were observed in all specimens. The increase in hardness mainly depended on the formation of the solute atom clusters. The square root of the volume fraction of the solute atom clusters provided a good correlation with the increase in hardness. The effects of dose rate and dose rate change during irradiation were explained by the formation of solute atom clusters.     

系统低剂量率失效和加速模拟试验方法

综述双极器件和双极线性电路在低剂量率辐射环境下的增强损伤,它可引起系统的早期失效。分析了引起低剂量率失效的物理机制,它与MOS器件电离辐射的损伤机制完全不同。为了缩短模拟试验时间和提高效/费比,研究了几种加速模拟试验方法,并对处于低剂量率下系统的加固保证也提出了一些看法。