The collective dose equivalent in evaluated region of bone-coal power stations and bone-coal shafts

1 Introduction The reserve of bone-coal in Hubei, Hunan, Ji-angxi, Zhejiang and Anhui Provinces accounts for about 90% of total reserve in China. More than two hundred years ago, local people spontaneously started to mine the bone-coal on a small scale. At present, the bone-coal is not only used to make lime and then the lime used as a building material or to improve the soil, but also used as a kind of fuel for generating electric-ity. However, the chimney’ exhaust of the bone-coal power …     

Numerical and theoretical investigations of heat transfer characteristics in helium–xenon cooled microreactor core

Helium–xenon cooled microreactors are a vital technological solution for portable nuclear reactor power sources. To examine the convective heat transfer behavior of helium–xenon gas mixtures in a core environment, numerical simulations are conducted on a cylindrical coolant channel and its surrounding solid regions. Validated numerical methods are used to determine the effect and mechanisms of power and its distribution, inlet temperature and velocity, and outlet pressure on the distribution and...     

Survey of radon concentrations in bone-coal mining areas and inside BCCB houses in five provinces

1 Introduction According to the National Investigation of Natu- ral Radioactive Level (abbreviated as “the investiga- tion of levels” below) during 1983-1990, the specific activities of radionuclides in bone-coal are relatively high. It is a man-made activity which may signifi- cantly increase the radioactive level of environment and the public dose, when the local peasants sponta- neously mine the bone-coal, produce bone-coal cinder bricks (BCCB, commonly called as carbide brick) with bo…     

Measurement of surface charges on the dielectric film based on field mills under the HVDC corona wire

The ion flow field on the ground is one of the significant parameters used to evaluate the electromagnetic environment of high voltage direct current (HVDC) power lines. HVDC lines may cross the greenhouses due to the restricted transmission corridors. Under the condition of ion flow field, the dielectric films on the greenhouses will be charged, and the electric fields in the greenhouses may exceed the limit value. Field mills are widely used to measure the groundlevel direct current electric fields under the HVDC power lines. In this paper, the charge inversion method is applied to calculate the surface charges on the dielectric film according to the measured ground-level electric fields. The advantages of hiding the field mill probes in the ground are studied. The charge inversion algorithm is optimized in order to decrease the impact of measurement errors. Based on the experimental results, the surface charge distribution on a piece of quadrate dielectric film under a HVDC corona wire is studied. The enhanced effect of dielectric film on ground-level electric field is obviously weakened with the increase of film height. Compared with the total electric field strengths, the normal components of film-free electric fields at the corresponding film-placed positions have a higher effect on surface charge accumulation.     

Effect of parallel resonance on the electron energy distribution function in a 60 MHz capacitively coupled plasma

In general, as the radio frequency(RF) power increases in a capacitively coupled plasma(CCP), the power transfer efficiency decreases because the resistance of the CCP decreases. In this work, a parallel resonance circuit is applied to improve the power transfer efficiency at high RF power, and the effect of the parallel resonance on the electron energy distribution function(EEDF) is investigated in a 60 MHz CCP. The CCP consists of a power feed line, the electrodes, and plasma. The reactance of...     

C2F6 /O2 /Ar Plasma Chemistry of 60 MHz/2 MHz Dual-Frequency Discharge and Its Effect on Etching of SiCOH Low-k Film

This work investigated C2F6/O2 /Ar plasma chemistry and its effect on the etching characteristics of SiCOH low-k dielectrics in 60 MHz/2 MHz dual-frequency capacitively coupled discharge. For the C2F6/Ar plasma, the increase in the low-frequency (LF) power led to an increased ion impact, prompting the dissociation of C2F6 with higher reaction energy. As a result, fluorocarbon radicals with a high F/C ratio decreased. The increase in the discharge pressure led to a decrease in the electron temperature, resulting in the decrease of C2F6 dissociation. For the C2F6/O2 /Ar plasma, the increase in the LF power prompted the reaction between O2 and C2F6 , resulting in the elimination of CF3 and CF2 radicals, and the production of an F-rich plasma environment. The F-rich plasma improved the etching characteristics of SiCOH low-k films, leading to a high etching rate and a smooth etched surface.     

Friction force effects on vertical manipulation of nanoparticles

In humid environment,a particles can be picked up from the substrate by the capillary force,such as in the colloidal probe of atomic force microscopy technique.In this paper,a model of the capillary bridge between spherical particles is used to study effect of the friction force in nanoparticles manipulation.Based on the Young-Laplace equation,Newtonian equation and adopted the constant volume boundary condition to calculate the particle motion,the friction force effects on nanoparticles manipulation are analyzed.The results show that the friction force has little effect on the particle motion,and the particle velocity decreases slightly in presence of the friction force.The friction force is opposed to the motion of the nanoparticle.As the tip velocity increases,there is a critical velocity beyond that the particle cannot be picked up from the substrate,and the critical velocity decreases in presence of the friction force.These provide a better understanding of the nanoparticle mechanical properties in humid environment.     

Estimation of the resident’s additional dose in bone-coal mining areas of the five provinces

1 Introduction In the National Investigation of Natural Radioac-tive Levels (abbreviated as “investigation of levels” hereinbelow) during 1983 to 1990, it is found that the specific activities of radionuclides in bone-coal are relatively high. The increase of radioactive level in the environment and the rise of the public accepted dose might be caused by some artificial activities, which include mainly mining and utilizing spontaneously bone-coal by local peasants, producing bone-coal cind…     

Electromagnetic–thermal–structural coupling analysis of the ITER edge localized mode coil with flexible supports

In a fusion reactor, the edge localized mode(ELM) coil has a mitigating effect on the ELMs of the plasma. The coil is placed close to the plasma between the vacuum vessel and the blanket to reduce its design power and improve its mitigating ability. The coil works in a high-temperature,high-nuclear-heat and high-magnetic-field environment. Due to the existence of outer superconducting coils, the coil is subjected to an alternating electromagnetic force induced by its own alternating current and the outer magnetic field. The design goal for the ELM coil is to maintain its structural integrity in the multi-physical field. Taking as an example the middle ELM coil(with flexible supports) of ITER(the International Thermonuclear Fusion Reactor), an electromagnetic–thermal–structural coupling analysis is carried out using ANSYS. The results show that the flexible supports help the three-layer casing meet the static and fatigue design requirements. The structural design of the middle ELM coil is reasonable and feasible. The work described in this paper provides the theoretical basis and method for ELM coil design.     

Deposition Mitigation of the First Mirrors Exposed in EAST with Metal and Carbon Mixed Wall Materials

In order to investigate the effect of aperture geometry on deposition mitigation, stainless steel （SS） first mirrors （FMs） were fixed on the holders of protective aperture geometry with different depth-diameter ratios （DDRs） and exposed in the deposition dominated environment of EAST. A baffle was used during the wall conditioning. The surface properties and reflectivity of the FMs were characterized before and after exposure. It is shown that using aperture geometry and a baffle can effectively mitigate the impurities deposition. The degradation of the surface and specular reflectivity of the FMs is reduced with the increase of DDRs in the range of 0 to 2. The main contaminated elements in a low-Z and high-Z mixed wall materials environment were still carbon and oxygen.     

Investigation on natural radionucildes levels in multiple media in bone-coal mine areas of five provinces

This paper reports methods and results of the investigation of natural radionuclides levels in multiple media in the bone-coal mine areas in Hubei, Hunan, Jiangxi, Zhejiang, and Anhui Provinces. In the studied bone-coal mine areas, the specific activities of ^238U and ^226Ra in the soil samples were 0.37 and 0.24 Bq/g, respectively; the specific activities of ^226Ra in the samples of bone-coal, bone-coal cinder and bone-coal cinder brick （BCCB） were 1.3, 1.4 and 0.9 Bq/g, respectively. In the water samples collected fiom the bone-coal mine areas, the average concentrations of natural uranium and ^226Ra were 33μg/L and 58 mBq/L, respectively, while in the water samples collected from outside the bone-coal mine areas, they were 3.4μg/L and 45 mBq/L, respectively. In addition, the specific activities of ^238U and ^226Ra in air aerosol samples from the bone-coal mine areas were 0.6 and 0.5 mBq/m^3, respectively.     

Investigation of environmental activity levels of bone-coal mining area in five provinces

During 1991-1993, the activity levels of the bone-coal mines were investigated in Zhejiang, Hubei. Hunan,Jiangxi and Anhui Province, respectively, where the reserve of bone-coal is about 90% of our country‘s total reserve.The average ofγ radiation doserate level measured for bone-coal, bone-coal cinder (BCC) and bone-coal cinder brick (BCCB) in these provinces is about 500 nGy/h, 400 nGy/h and 700 nGy/h respectively, while that for fields, roads and houses made of BCCB in corresponding regions of these provinces is about 200 nGy/h, 260 nGy/h and 300 nGy/h respectively. It is shown that the environmental activity level of bone-coal mining area is about 3 times higher than the reference spots.     

Natural radioactivity level of associated bone-coal mining area in Zhejiang Province

The geographic distribution, γ-radiation level and specific activity of radionuclides of the bone-coal mines in Zhejiang Province were reported. The weighted average of γ-radiation dose rate of the bone-coal mines is 566 nGy/h for 107 main bone-coal mines. The weighted mean activity of ^238U, ^226Ra, ^232Th and ^40K in the samples are 949,918, 34 and 554 Bq/kg for 171 samples of bone-coal, respectively.     

Estimation of the resident''s additional dose in bone-coal mining areas of the five provinces

This paper introduces the resident's additional dose in bone-coal mining areas. The increase of the annual additional effective doses accepted by the residents living in the carbide-brick houses, the staffs working in the carbide-brick houses and the miners working in the bone-coal mining areas of Hubei, Hunan, Jiangxi, Zhejiang and Anhui Provinces is caused by the rising of environmental radioactive level. The investigation of natural background radiation in the bone-coal mining areas indicated that both mining and utilizing bone-coal cause the rise of environmental radioactive level. The ranges of the annual additional effective dose accepted by the residents, staffs and miners is 1.9-6.8 mSv, 0.5-2.0 mSv and 8.2-71 mSv, and with an average of 3.8 mSv, 1 mSv and 40 mSv, respectively. The annual additional effective doses accepted by part residents and staffs exceed the dose limit of 1 mSv for public exposure, and part miners exceed the dose limit of 20 mSv for occupational exposure. And the contribution of dose caused by inhaled radon to the total additional effective dose is over 76%.     

Radioactivity level of the ambient environment of Anren bone—coal power station

The radioactivity level of the ambient environment of Anren Bone-coal Power Station(BCPS) was investigated systematically.The γ radiation dose rate level in the environment ,the content of ^238U and ^226Ra in the ambient soil and the farmland in the direction of downwind,the concentrations of ^238U,^232Th,^226Ra,^40K and ^222Rn,as well as α potential energy in air,and the concentrations of natural U and Th in effluent are all higher than the corresponding values of the reference site.The additional annual effective dose equivalent to the residents living in the houses made of bone-coal cinder brick is 2.7mSv.     

江苏省伴生放射性矿开发利用中环境保护管理的现状及改进

介绍了江苏省伴生放射性矿开发利用中环境保护管理的现状,针对环保管理中存在的未履行环评和验收手续、废渣的转移及处理不申报、废水排放超标、对放射工作场所及人员的管理要求不够明确等问题,提出相应的管理对策.     

江西省修水县石煤矿区放射性环境调查与评价

石煤的开发和综合利用对环境有可能造成一定的污染,其中影响环境放射性水平增高和居民受照剂量增加等辐射方面的污染问题较为敏感以及突出。本次研究对江西省主要石煤资源区——修水县一处典型石煤矿的放射性环境进行调查,通过多介质采样分析以及现场监测γ辐射空气吸收剂量率和地面γ能谱相结合,综合研究该区放射性核素分布与环境γ剂量率之间的关系,利用公式估算石煤矿区居民辐射剂量并评价其环境辐射情况。结果表明,调查范围内的石煤矿区地面γ辐射空气吸收剂量率的平均值达到了662 nGy/h,该处铀矿主要形式为碳硅泥岩型,区内石煤、石煤渣、土壤、水样放射性核素测量值都高于省内相应介质的本底值,石煤矿的开采需接受专业的监管。     

Risk analysis using data from radioecological monitoring

A methodology for performing risk analysis based on data obtained from radioecological monitoring is presented. Examples of the application of risk analysis to optimization of radioecological monitoring and assessment of the total radiation effect on components of the environment are presented. The integral indicators of the effect on radioactivity of atmospheric air and surface waters are calculated according to the criterion that the negligibly small risk is not exceeded and modern data from observations for various types of radiation objects in Russia: Mayak Industrial Association; Krasnoyarsk Mining and Chemical Works; Beloyarskaya, Novovoronezh, and Smolensk nuclear power plants; and others. It is shown that under regular conditions the objects of a nuclear power complex do not have an appreciable radiation effect on the components of the environment.