宝鸡燃煤电厂原煤及粉煤灰中天然放射性水平

本文调查测量了宝鸡电厂原煤（3个样品）、粉煤灰（17个样品）、底灰（6个样品）中天然放射性核素^226Ra、^232Th和^40K的比活度，分析了燃煤产生的底灰和粉煤灰中上述核素的含量特征，及其与原煤相比的浓集倍数。宝鸡电厂原煤和粉煤灰样品中天然放射性核素^226Ra、^232Th和^40K的比活度水平与北京电厂和上海电厂的接近。依据国家标准（GB6566-2001），对宝鸡电厂粉煤灰用作建筑材料的可行程度进行了评价，得出当建材原料100％为粉煤灰时，约有29％的样品超过国家标准的限制值。所以，应对用作建材原料的粉煤灰作放射性检测，选用合格的部分，控制高比活度粉煤灰在建材原料中的配比，以确保达到合理使用的效果。     

γ-Spectrometric determination of the content of natural radionuclides in natural waters

Our investigations have shown that γ-spectrometry can be used to determine with acceptable accuracy the natural radionuclide content of natural waters, starting with specific activity 1.5 Bq/kg of the radionuclides in the samples. The accuracy of the determination of the activity can be increased by using an inert sample, which is certified with respect to the natural content of radionuclides, and better detectors. The natural content of radionuclides in the experimental samples of natural waters of Uzbekistan does not exceed the maximum admissable concentration. 3 figures, 1 table, 4 references. Translated from Atomnaya énergiya, Vol. 86, No. 1, pp. 36–40, January, 1990.     

全国水体中天然放射性核素浓度调查的质量保证

本文总结了全国水体中天然放射性核素浓度调查的质量保证工作，内容包括调查中的质量管理、各种核素浓度量值的可追溯性以及实验室分析的质量控制。由本实验室制备的各种参考溶液经中国计量科学研究院等实验室核实，其量值可追溯到国家计量部门。有３１个实验室参加了分析方法的考核，结果表明，Ｕ、Ｔｈ、２２６Ｒａ和Ｋ的分析误差在±１５％以内的实验室分别占９６．８％、９６．８％、８７．１％和８７．１％。全部实验室测定上述核素的误差均小于±３５％。     

两种稀土产品中放射性核素分析研究

利用高纯锗γ谱仪对两个稀土产品氯化镧和氯化钇的样品进行能谱分析,研究经湿法冶炼工艺后的稀土产品中放射性核素的活度变化。结果表明,样品中存在天然放射性钍系和锕-铀系的核素,以及天然放射性核素138La和176Lu,但两个样品中所含的放射性核素不相同。氯化镧产品中锕-铀系和钍系核素放射性未达平衡,其主要子体224Ra和227Th的含量随时间发生明显变化,约60天达到平衡;而氯化钇产品没有这种现象。     

天津市地下水和地热流体中天然放射性核素调查与评价

对天津市地下水和地热流体中的天然放射性核素活度浓度水平进行调查,并根据调查结果评价天津市居民因饮用地下水和地热流体所致的内照射剂量。调查结果显示天津市地下水和地热流体中的天然放射性核素活度浓度属正常水平,未发现放射性水平异常状况。     

中国近海海域环境放射性水平调查

总结中国在过去40年中对近海海域环境放射性的调查结果，介绍了中国近海海域中天然和人工放射性核素的水平，海洋生物对放射性核素的吸收与累积，以及海洋沉积物对放射性核素的吸附。     

Gamma-ray measurements of natural radioactivity in sedimentary rocks from Egypt

The aim of this study was to measure concentrations and distributions of natural radionuclides occurring mentary rock samples from Eastern Desert (Um El-Huetat), Nile Valley (Gebel Owina) and from southwest Sinai (Wadi Ghweiba) were measured using a high-purity germanium detector. The samples under investigation (clay, shale and sandstone) were used as raw materials in the construction industry (bricks, ceramics, cement, fillers, etc.). Though the sediments of Egypt have already been investigated in the geological and mineralogical aspects, it is necessary to investigate the natural radioactivity in order to complete their classification. The average concentration values of 226Ra, 232Th, 40K in the surveyed samples were 47 ± 7,21± 5, 393±19 Bq.kg-1 (clay); 23 ± 5, 30 ± 6, 563 ± 24 Bq.kg-1(shale); and 17 ± 4, 14 ± 4, 299 ± 17 Bq.kg-1 (sandstone), respectively. All sediment samples have radium equivalent natural radionuclides present in the samples have been computed and compared with the global averages. In terms of the radiation safety, the natural radioactivity of the sediment in Egypt is below the recommended limits of the gamma dose rate. Therefore, they can be used for all kinds of public buildings.     

Development of Three-Dimensional Numerical Model for 222Rn and Its Decay Products Coupled with a Mesoscale Meteorological Model II. Numerical Analysis on the Increase in Gamma Dose Rate Observed in the Coastal Area of Fukushima Prefecture

A three-dimensional Eulerian numerical model for ²²²Rn and its decay products coupled with a mesoscale meteorological model, MM5-TMNR, is applied to investigate the mechanism of the naturally induced increase in gamma dose rate observed at the coastal area of Fukushima prefecture in October 2002. The results obtained by MM5-TMNR are verified by comparisons with observed wind, precipitation and gamma dose rate to be adequate for examining the mechanism. The unusual increase in gamma dose rate is observed by the combination of the synoptic-scale (about 2000 to 5000 km horizontally) transport of natural radionuclides due to the inflow of cold air mass from the Asian Continent and the meso-_-scale (about 20 to 200 km horizontally) precipitation process within the coastal area of Fukushima prefecture. The contribution rate of natural radionuclides from the Asian Continent to the increase in gamma dose rateis estimated to be more than 60%.     

Is the thermodynamic approach appropriate to describe natural dynamic systems? (Status and limitations)

The long-term performance assessment of a nuclear waste repository entails sound knowledge on the migration behaviour of radionuclides in a given aquifer system, which can in principle be appraised by a well-founded thermodynamic approach. For various reasons, in such an endeavour, a number of uncertainties are involved, which cause difficulties in the application of a thermodynamic approach to natural dynamic systems. This paper summarises the present state of the thermodynamic approach being applied to the assessment of various geochemical reactions of radionuclides and discusses the limitations involved in application to laboratory systems as well as dynamic natural systems.     

Dose Loads on Hydrobionts and the Population Living in the Operational Regions of Nuclear-Powered Ships

Data accumulated over many years of observations of radioecological conditions are used to analyze the accumulation coefficients for technogenic radionuclides in hydrobionts in interior bukhtas and zalivs in the north-western part of the Sea of Japan. Attention is focused on estimating the contribution of technogenic radionuclides to the dose according to their accumulation coefficients in marine biota and to determine more accurately the contribution of natural ⁴⁰K to the total dose in the operational regions of nuclear-powered ships. On individual local sections of bukhtas and zalivs, the dose due to external irradiation from technogenic radionuclides in bottom deposits exceeds the natural level (regions of radiation accident in bukhta Chazhma, near the nuclear-powered submarine with the damaged nuclear power system in bukhta Pavlovskogo). However, the total dose due to technogenic irradiation of hydrobionts as a whole remains low and falls outside the dose range at which negative effects of radiation for marine organisms are observed.     

Radiational impact of mining on the population at large

Conclusions The exploitation of mineral deposits containing natural radionuclides (even in concentrations too small for industrial use) may pose radiation hazards for the nearby population on account of radioactive discharge into the water and the atmosphere and the seeping of radon into living quarters. This risk is especially great if the protective belt around the mine is established incorrectly, settlements are laid out without paying attention to the radioecological conditions, or mine wastes are used without supervision in building houses. The technology and equipment here described permits investigation of the distribution of radioactive discharges at mineral deposits. Experience in monitoring the radiation hazards in the region of the Kovdorsk mining and enrichment combine, the Belaya Zima prospecting region, and elsewhere may be used wherever natural radionuclides are present as primary of secondary components. However, it is necessary to employ high-accuracy methods and equipment permitting the use of milligram samples; in particular, laser-luminescent analysis of uranium in the samples is recommended. It is important to develop and publish standard documents on estimating the radiation hazards of mineral deposits, both for the protection of the population and as a means of preventing irrational fear of radiation, which is often a greater threat to the public health than are natural radionuclides themselves. A. A. Logachev All-Russian Scientific-Research Institute of Exploratory Geophysics. Translated from Atomnaya énergiya, Vol. 84, No. 4, pp. 299–303, April, 1998.     

广东省进出口食品中的放射性检验

报道了广东省商检中心放射性检验室开展的广东进出口食品中的放射性检验工作。介绍了检验工作采用仪器的主要性能及应用；给出了分析测量方法和探测下限以及实验的质量保证措施，并给出了检验室测量的广东省几种食品中的放射性含量范围，测量结果与我国食品中放射性活度变化范围大体一致。     

Natural γ-ray-emitting radionuclides in Egyptian cement

Samples of cement manufactured in Egypt and the raw materials have been analyzed using gamma-spectroscopy, in order to determine the concentration of natural radionuclides and associated radiological hazard. The mean of specific activity due to radionuclides of 226Ra, 232Th and 40K was found to be (20±4), (11± 2),(320±18) (gypsum), (41±8), (27±5), (410±27) (clay), (58±11), (18±3), (321±20) (iron ore) and (37.6±6), (11.8±3),phate resistant cement (S.R.C.), clinker and white cement, while the mean specific activities of 226Ra and 232Th are activities (concentrations) are in the same range as the data released in other countries. The calculated radiation hazard parameters for all the samples are still lower than the acceptable values in Egypt and other countries.     

Annals of the ICRP. A report of: doses to infants from ingestion of radionuclides in mothers' milk

In the present report, ICRP provides information on radiation doses to the infant due to intakes of radionuclides in maternal milk. As in Publication 88 (ICRP, 2001) on doses to the embryo and fetus following intakes of radionuclides by the mother, intakes by female members of the public and female workers are addressed. Acute and chronic intakes are considered at various times before and during pregnancy as well as during the period of breastfeeding. Dose coefficients per unit intake by the mother (Sv/Bq) are given for the selected radionuclides of the same 31 elements for which age-specific biokinetic models were given in Publications 56, 67, 69, and 71 (ICRP, 1989, 1993, 1995a,b). For these elements, doses were calculated for the most radiologically significant natural or artificial radionuclides that might be released into the environment due to various human activities. Dose coefficients are also given in this report for radionuclides of an additional four elements: sodium, magnesium,phosphorus, and potassium. Relevant human and animal data on elemental and radionuclide transfer to milk are reviewed. The biokinetic models for adults given in earlier ICRP publications are adapted to include transfer to milk. Model predictions of fractional transfer of ingested or inhaled activity to milk are discussed in the report, and the corresponding dose coefficients for the infant are compared with dose coefficients for in utero exposure, as given in Publication 88 (ICRP, 2001). Illustrative information is also given on doses to the female breast from radionuclides in breastmilk, and external doses received by the child from radionuclides retained in the tissues of the mother. For the additional elements considered in this report, but not in Publication 88 (ICRP,2001), information is also given on doses to the embryo and fetus following maternal intakes of radioisotopes during or before pregnancy. A CD-ROM is to be issued giving data that will supplement the information given in this report. In addition to the dose coefficients given here, committed equivalent doses to the various organs and tissues of the offspring will be given. Dose coefficients will also be given for inhalation of a range of aerosol sizes for the selected radionuclides of the elements covered by this report.     

Measurement and calculation of cross section for (p,x) reactions on natural Fe for 650 MeV protons

Cross sections for production of radionuclides in (p,x) reactions on natural iron were measured for protons of 650 ± 4 MeV with the use of HPGe gamma spectrometry and calculated with the MCNPX code. The determined cross section values were compared with the computed and other experimental ones.     

广东省部分陶瓷产品的放射性水平

对广东省主要陶瓷产地(南海、佛山和潮州三市)的陶瓷产品中的天然放射性水平进行抽样检测，结果表明：所检测154个样品中95％的样品放射性含量指标符合国家标准GB6566-2001《建筑材料放射性核素限量》规定的A类产品标准。     

How to cope with the hazards of nuclear fuel waste

Many countries are developing concepts for geological disposal to achieve a permanent method of managing nuclear fuel wastes. This paper reviews the hazardous characteristics of nuclear fuel waste and discusses, in a semi-quantitative manner, the containment and retardation potential of various engineered and natural barriers. A durable waste form would retain the vast majority of radionuclides for many tens of thousands of years. Of the small inventory of radionuclides released from the waste form, many with relatively short half-lives decay to non-hazardous levels before release from the engineered barriers. The geosphere also has considerable containment potential, depending on its geological and hydrogeological properties. Approaches to selecting suitable combinations of engineered and natural barriers are illustrated based on long-term performance assessment case studies carried out in the Canadian Nuclear Fuel Waste Management program.     

Level-1, -2 and -3 PSA for AHWR

In nuclear reactor probabilistic safety analyses (PSAs), risk is usually defined by the frequency and magnitude of radioactive releases to the environment (Generic CANDU, 2002). An integrated Level-1, -2 and -3 PSA have been carried out for thorium based natural circulation driven advanced heavy water reactor (AHWR). A Level-1 PSA models accident sequences up to the point at which the reactor core either reaches a stable condition or becomes severely damaged, releasing large amounts of radionuclides into the containment. The probabilistic aspects of the analysis focus on the performance and reliability of nuclear plant systems and station staff in response to plant upsets. A Level-2 PSA examines severe reactor accidents through a combination of probabilistic and deterministic approaches, in order to determine the release of radionuclides from containment, including the physical processes that are involved in the loss of structural integrity of the reactor core (Generic CANDU, 2002). A Level-3 PSA goes through the short and long term (radiological) effects on the public (Fullwood, 2000). In this study the risk associated with internal events is only addressed. In the first phase, Level-1 PSA has been carried out to identify postulated initiating events (PIEs) which may lead to severe core damage (SCD) for the reactor. In the second phase, a Level-2 PSA examines two enveloping severe accidents through a combination of probabilistic and deterministic approaches and determines the release of radionuclides from containment. In the third phase, a Level-3 PSA is carried out for the transport of radionuclides through the environment and for the evaluation of public health risk for the two scenarios considered. The salient findings are presented in the paper.     

核素在非饱和黄土介质中的二维迁移

试验结果表明，天然降水条件下，在近3年的试验期间，^60Co,^85Sr和^134Cs三种核素在非饱和黄土介质中的比活度分布质心仍在示中源层这内，^85Sr的侧向比活度分布方差与纵向比活度分布方差相当；在人工喷淋条件下，这些核素的迁移距离也很短，说明非饱和黄土对这些核素有较强的吸附滞留能力。或者换句话说，非饱和黄土可以作为中低放废物处置的候选地质介质。另外，根据对试验结果的拟合与分析看出，降水入渗量极大地影响着核素向下的迁移速度和纵向扩展，因此，控制流经处置库的入渗水量，是减少处置废物中放射性核素对环境影响的重要因素。