公众液态途径辐射剂量对吸附分配系数的响应研究

针对辐射剂量计算的不确定性,运用放射性核素浓度计算模式和公众个人照射剂量计算模式,计算了我国某核电厂正常运行下某子区代表居民液态途径的辐射剂量,分析了公众液态途径辐射剂量对核素悬浮物吸附分配系数的响应。结果表明:当核素~(60)Co和~(137)Cs的悬浮物吸附分配系数降低一个数量级时或升高一个数量级时,岸边沉积外照射剂量响应较为明显。特别是~(137)Cs,其悬浮物吸附分配系数降低或升高一个数量级,该核素岸边沉积剂量贡献占其液态途径剂量比值和占总岸边沉积剂量比值都有明显变化。     

UNSCEAR—1982报告附件B 天然辐射源的照射内容简介

人类始终受到来自天然环境辐射源的照射。评价人类受天然辐射源照射的辐射剂量具有特别重要的意义,因为天然辐射是世界居民集体剂量的最大来源。天然辐射源分为外部辐射源(产生外照射)和内部辐射源(产生内照射)两大类。外部辐射源包括:宇宙射线、地层(岩石和土壤),建筑材料以及空气中的放射性核素。内部辐射源包括进入人体的各种放射性核素。     

燃煤电厂气载放射性排出物对环境影响的辐射剂量评价

根据苏州某大型燃煤电厂烟尘排放所致周围环境近地面空气中天然放射性核素的浓度和地面沉积量及其分布的计算结果和辐射剂量的估算模式,估算了该厂气载放射性排出物导致厂区周围半径100km范围内经蔬菜、农作物摄入、漂尘吸入和地表沉积γ的内外照射途径公众居民所受的个体全身年平均剂量当量和集体剂量当量。估算结果表明,最大污染浓度的下风向SW～NW区间距烟囱1km处的个体全身年平均剂量当量值为3.13×10~(-4)Sv(GW·a)~(-1),其中 由摄入和吸入途径所受的内照射剂量分别为3.02×10~(-4)Sv(GW·a)~(-1)和8.14×10~(-6)Sv(GW·a)~(-1);地表沉积γ外照射剂量为2.94×10~(-6)Sv(GW·a)~(-1)。厂区周围半径100km范围内公众居民的集体剂量当量值为30.5man-Sv(GW·a)~(-1),其中摄入和吸入途径的内照射剂量分别为26.5和3.70man-Sv(GW·a)~(-1);地表沉积γ外照射剂量为0.34man-Sv(GW·a)~(-1)。     

基于尿样测量的~(241)Am内照射常规监测与评价技术研究

~(241)Am属于极毒组α核素,吸入人体将产生内照射危害。尿样核素分析监测技术是工作人员内照射常规监测与评价的重要方法之一。本文通过研究~(241)Am大体积尿样的前处理、分离纯化、电沉积等因素,建立了大体积尿样中~(241)Am的分析监测技术,同时考察了该分析监测技术在~(241)Am内照射监测与评价中的应用。研究结果表明:建立的大体积尿样中~(241)Am分析监测技术化学回收率为86.2%、精密度为3.88%、相对偏差小于10%;对Pu的去污系数大于1.0×10~3;探测限为31.8μBq/L。对于1.6 L 24 h尿样,常规监测周期为360 d时,最小可测待积有效剂量为0.13 mSv,低于常规监测所规定的2 mSv调查水平,表明该监测技术适用于工作人员~(241)Am内照射的常规监测以及剂量评价。     

建材天然放射性对丹东市居民健康风险评价

为明确建筑材料对丹东市居民内外照射指数与年有效剂量贡献,采用高纯锗谱仪测试了丹东市主要建筑材料(红砖、空心砖、大理石、水泥、混凝土)²²⁶Ra、²³²Th和⁴⁰K的放射性比活度,通过计算其内外照射指数和年有效辐射剂量,并与相关标准比较,评价其对丹东市居民健康的安全性。结果表明,丹东市建筑材料天然放射性核素比活度⁴⁰K贡献最大,混凝土放射性比活度较低;建筑材料内照射指数为0.15～0.48,外照射指数为0.29-0.79,符合国家标准;某大理石厂生产的大理石样品年外照射有效剂量为1.23 mSv·a^-1,超过国际建议上限1 mSv·a^-1,应该慎重使用。其他建筑材料年照射有效剂量值为0.45～0.99 mSv·a^-1。总体上,丹东市建筑材料天然放射性对居民健康影响可以忽略。     

次锕系核素在铅冷快堆中的嬗变性能

乏燃料中大部分次锕系(minor actinides,MA)核素半衰期较长,对环境具有长期放射性危害。分离-嬗变技术将次锕系核素从高放废液中分离出来,并通过反应堆嬗变为短寿命或稳定核素,从而消除其放射性危害。为研究次锕系核素与燃料均匀混合、制成嬗变棒和做燃料芯块镀层装载方式下在铅冷快堆中的嬗变特性,采用MCNP和SCALE程序进行模拟计算。结果表明,三种方式下~(237 )Np、~(241 )Am、~(243 )Am和混合次锕系核素使有效增殖因数k_(eff)降低,而~(244 )Cm和~(245 )Cm使k_(eff)升高,且~(245 )Cm可使k_(eff)大幅度增加。不同质量的混合次锕系核素装载后,三种方式下堆芯k_(eff)都随装载量的增加而降低,降低幅度由小到大分别为嬗变棒、均匀混合和镀层。不同次锕系核素装载量以均匀混合方式在堆芯经过550d辐照后,~(237 )Np、~(241 )Am和~(243 )Am嬗变率均为正值,其中~(241 )Am嬗变率最大,而~(244 )Cm和~(245 )Cm嬗变率均为负值,~(245 )Cm增加明显,总的次锕系核素嬗变率为14%,可为次锕系核素在铅冷快堆中嬗变性能评价提供参考。     

基于一阶广义微扰理论的燃耗灵敏度系数计算

采用一阶广义微扰理论,开发燃耗计算中核素的核子密度对反应截面的灵敏度分析程序。分析各核素的反应截面对244Cm在50 GW·d/t时核子密度的灵敏度系数,235U和239Pu的裂变截面和238U、240Pu、241Pu、242Pu以及243Am的俘获截面具有较大的灵敏度系数;243Am俘获截面的灵敏度系数在热中子区和共振区明显大于快中子区,因此243Am俘获截面精度的改善应该优先考虑热中子区和共振区。     

《秦山核电厂事故剂量快速估算手册》的编制原理及内容介绍

本文介绍秦山核电厂事故后剂量快速估算方法。以WASH-1400报告给出的九类事故假设,分别估算了地面空气中各类核素的时间积分浓度、地面沉积污染浓度、烟羽Υ外照射剂量、地面沉积外照射剂量、皮肤沉积外照射剂量、烟云吸入内照射剂量和食入污染蔬菜所致内照射剂量的方法。文中并以部分数据为示例。     

文献题录

Radiation Protection Dosim etry　 Vol.98No.12 0 0 2放射性核素与辐射防护数据手册　第二版 ( 2 0 0 2 )放射性核素的分类放射性核素的物理特性放射性控制　　外照射危险　　内照射危险　　工作人员的剂量限值外照射　　假设　　远距离 (点源 )外照射　　非均匀污染表面的照射β和γ发射体的屏蔽污染　　外部皮肤污染的接触照射　　衰变产物　　重元素的衰变　　导出表面污染限值 ( DSCL)可去除的和固定污染值的测定　　污染控制　　检测探针内照射　　单位摄入量的待积有效剂量　　年摄入量限值 ( ALI)　　“最高剂量器官”　　总…     

~(241)Am所致大鼠外周血淋巴细胞的染色体畸变

核工业的不断发展,超钚核素的生产、研究、应用范围随之扩大,而辐射危害问题也就越来越引起学者的重视。研究核工厂超钚核素操作人员细胞遗传学的剂量效应关系显得十分重要。 ~(241)Am作为一种超钚核素,主要积聚在肝和骨皮质,是高毒内照射核素。Mckay曾报道~(241)Am所致肝细胞染色体畸变率随累积剂量呈明显的线性增加的剂量效应关系,其RBE值比~(60)Co高出40倍。而关于~(241)Am诱发外周血淋巴细胞染色体畸变的研究     

Radiation Exposure Normalization Taking Account of Specific Effects at Low Doses and Dose Rates

Epidemiological studies of the consequences of radiation exposure of humans already prove that at low dose rates 85% of radiation-induced cancer arises only above a threshold dose from 0.3 to 30 Sv, and sometimes radiation hormesis occurs. In this question, the ICRP and the RNCRP rely on unreliable information and an incorrect linear zero-threshold dose–effect relation model. Two new principles of radiation safety are proposed and a model for normalizing radiation exposure on the basis of the new facts is also proposed. The model retains the adopted maximum lifetime individual risk of death due to radiation-induced cancer, but the dose in organs determines this risk. For uniform whole body radiation exposure, the dose creating the indicated limit can be taken as the equivalent dose. It will equal 150 mSv/yr. According to the model, during the initial years of radiation exposure there is no carcinogenic risk at all. The need for normalizing the content of radionuclides in the human body and introducing other changes in the norms is substantiated.     

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.     

燃煤发电厂气态流出物辐射环境影响研究

目前，燃煤发电厂对环境和公众产生的辐射影响引起了广泛关注。本文选择长江沿岸具有代表性的三家燃煤发电厂为研究对象，基于电厂气态流出物中主要放射性核素的年排放量，采用烟囱直接排放和沉降进入水体两种途径的评价方法，评估燃煤发电厂气态流出物对周围环境造成的辐射影响。结果表明：三家燃煤发电厂气态流出物排放造成80 km范围内辐射影响很小，归一化最大个人年有效剂量分别为3.02×10^-4、4.32×10^-5、8.50×10^-5 Sv/GW；辐射剂量主要来自²¹⁰Po和²¹⁰Pb直接排放通过食入照射途径的贡献，远大于其进入水体及²²²Rn排放对剂量的贡献。由于²¹⁰Pb具有相对较长的半衰期，导致其在土壤中的比活度增加；基于文中²¹⁰Pb沉积浓度的分析，建议相关研究关注燃煤发电厂下风向30 km范围内²¹⁰Pb的长期辐射影响。本研究结果可为类似厂址的辐射影响评价提供技术支持，为内陆核电建设中公众沟通和技术研究工作提供基础数据，也为政府相关部门的决策提供参考。     

Estimating internal dose coefficients of short-lived radionuclides in accordance with ICRP 2007 recommendations

For radiation protection in high-energy accelerator facilities, internal dose coefficients of short-lived radionuclides were estimated using the dosimetric methodology in accordance with the International Commission on Radiological Protection (ICRP) 2007 Recommendations. A computational program was developed for estimating the dose coefficients. The program was verified by confirming whether it could reproduce the dose coefficients provided by ICRP for intakes of representative radionuclides. In addition, the estimated dose coefficients of short-lived radionuclides were compared to the values generated by Dose and risk CALculation software (DCAL), which is based on a dosimetric methodology that is in accordance with the ICRP 1990 Recommendations, to discuss the reasons why the dose coefficients were changed by the revision of the dosimetric methodologies. The comparison revealed a decreasing trend of dose coefficients in the case of inhalation upon revision of the dosimetric methodologies. By contrast, in the case of ingestion, the dose coefficients tended to increase.     

高温气冷堆核电站示范工程新燃料运输辐射风险研究

探索了将概率安全评价（PSA）方法系统地应用于放射性物品运输的辐射风险评价,分析了高温气冷堆核电站示范工程（HTR-PM）新燃料元件公路运输的辐射风险。基于实际路况数据和可能的事故情景,选择货包辐射水平升高和临界两种事故工况进行了事故频率分析。分析表明：货包辐射水平升高事故的发生频率为4.21×10^-7（车•单次运输）^-1;临界事故的发生频率低于1×10^-13（车•单次运输）^-1,可不考虑其辐射后果。对事故后果估算的结果表明：货包辐射水平升高事故对应急人员造成的最大外照射剂量为0.55 mSv,对附近公众造成的最大外照射剂量为4.55×10^-3 mSv,其辐射影响是可接受的。总体辐射风险为1.24×10^-10人•Sv/(车•单次运输),其中撞击事故对风险的贡献最大。     

Transport of low-level NORM – a case for consistency and practicality

Abstract

In 1996 the International Atomic Energy Agency (IAEA) adopted a system for exemption of lowlevel radioactive material from transport regulations based on the principle that exemption values should be commensurate with the risk posed by the material as represented by the maximum potential radiation dose to individuals. For many naturally occurring radionuclides the derived dose-based, radionuclide-specific exemption concentrations were substantially lower than the previous radionuclide-independent definition of radioactive material (70 Bq g^–1) [1900 pCi g^–1] due to the stringent dose criterion applied. It was recognised that this would bring large quantities of previously unregulated naturally occurring radioactive material (NORM) handled in industry into the scope of the transport regulations. To minimise the economic impact of the dose-based values, a special provision was included to provide for a 10-fold increase in exemption values for radionuclides in natural material provided the material is not intended to be, and has not previously been, processed for recovery of its radionuclides (the wording regarding previous use was added in 2003). This '10 times' or '10×' provision for certain natural material reflects a second concept underlying IAEA guidance, namely, that a dose criterion may be relaxed within cautious bounds to achieve a balance between practical issues and radiological concerns. On the other hand, restriction of the provision on the basis of past or intended use of the material is inconsistent with the basic principle underlying the Transport Regulations in that there is no risk basis for assigning different exemption values to identical materials on the basis of their past or anticipated use. In fact, the same material can move in and out of the scope of regulatory control as its anticipated use changes. As a practical matter, safety guidelines for potentially hazardous material should be based on measurable properties of the material and not the whims of human intentions. To improve the practicality as well as the consistency of the Transport Regulations as applied to NORM, the 10× provision should be revised to apply to all natural materials, regardless of their intended use.     

Estimation of exposure dose for decontamination workers from contaminated soil at a nuclear decommissioning site in Korea

Assessment of the exposure dose for workers is crucial to protecting workers from the radiological risk.This preliminary study estimates the potential radiological exposure for a soil remediation worker at a nuclear decommissioning site contaminated with Cs-137 in Korea,and then calculates the maximum workable soil concentration to comply with the occupational dose constraint of 20 mSv per year.The Korean characteristic data,detailed exposure scenarios for workers by the type of work,and relevant exposure pathways were used in the dose estimation.As a result,the most severe exposure-induced work type was identified as the excavator operation with an annual individual dose of 5.92×10^-5 mSv for a unit concentration of soil,from which the derived maximum workable soil concentration was 3.38×10⁵ Bq/kg.Furthermore,dose contribution by each exposure pathway was found to be decreased in the following order:external radiation exposure,soil ingestion,dust inhalation,and skin contamination.The results of this study are expected to be used effectively to optimize radiation protection for workers and establish appropriate work procedures for future site remediation.     

Radiation Conditions in Obninsk

Monitoring data are used as a basis to examine the radiation conditions in Obninsk, including an analysis of the radioactive emissions from the Physics and Power-Engineering Institute and the Scientific-Research and Physicochemical Institute, the content of technogenic radionuclides in atmospheric air, soil, surface waters, and the components of agricultural natural ecosystems, and an estimate of the dose and radiation risk to the public. The monitoring results show relatively low levels of technogenic radionuclides in the environment, much lower than the admissable values. It is recommended that regular radiation monitoring of the content of tritium in surface and underground waters and also iodine isotopes in air near the ground at Obninsk be continued. The total estimated dose, taking account of numerous pathways of technogenic irradiation of the public in Obninsk, is on the average about 10⁻⁵ Sv/yr, which corresponds to a negligibly low radiation risk, less than 10⁻⁶ under standard operating conditions of nuclear objects. __________ Translated from Atomnaya Energiya, Vol. 99, No. 3, pp. 214–221, September, 2005.     

伤口摄入241Am内照射回顾性调查及剂量评价

2002年某单位一名工作人员操作241Am固体放射源时，右手食指被螺丝刀穿刺扎伤，伤口摄入颗粒态241Am。2016年对人员伤口摄入241Am进行回顾性调查及剂量评价。对人员头骨中241Am的定量测量约为166 Bq，头骨干重占全身骨干重约18.86%，人员全身骨内241Am约为880 Bq。结合伤口摄入241Am人体骨骼滞留函数，计算人员伤口241Am摄入量约为2 630 Bq，待积有效剂量约为0.85 Sv。对人员伤口内现有241Am滞留量定量测量约为527 Bq，结合伤口污染滞留函数计算伤口241Am摄入量约为5560 Bq，待积有效剂量约为1.81 Sv。综合两种剂量评价方法的结果，该人员伤口摄入241Am待积有效剂量应小于2 Sv。对伤口现有241Am进行干预评估，伤口残留污染物手术切除可节省待积有效剂量约为170 mSv。     

公众成员某些放射性核素的吸入有效剂量系数

本文根据ＩＣＲＰ７１号出版物，给出了３１个元素的７４个放射性核素对公众的吸入有效剂量系数，并对它们的应用进行了简要讨论。这些核素是由于各种人类活动可能释放环境中去的并在环境辐射防护方面有重要意义的核素。