Burning of Reactor Grade Plutonium Mixed with Thorium in a Hybrid Reactor

Significant amount of plutonium have been discharged and accumulated from the conventional LWRs and CANDU reactors. Reducing this reactor grade (RG) plutonium is very important because it may be misused and/or released accidentally into the environment. Fusion-fission (hybrid) reactors have strong potential on burning plutonium effectively. This study presents the burning of RG plutonium mixed with thorium in a hybrid reactor for an operation period of 24 months. The effect of various fuel mixtures (98% ThO₂ + 2% RG-PuO₂, 94% ThO₂ + 6% RG-PuO₂ and 90% ThO₂ + 10% RG-PuO₂) and coolants (Flinabe, natural lithium and Li₂₀Sn₈₀) on the reactor’s performance was investigated. Numerical results showed that utilization of RG plutonium in the mixed fuel in such a hybrid reactor not only enhanced the reactor’s performance but also reduced its ²³⁹Pu content significantly.     

钍-铀燃料后处理中新萃取剂的研究——Ⅲ.N-正辛基己内酰胺萃取铀和钍

报道了N-正辛基己内酰胺(OCLA)-三甲苯从硝酸介质中萃取铀、钍的实验结果。OCLA对这两种元素的萃取规律类似于TBP,但分配系数(D)比TBP的高。用斜率法求得铀、钍的溶剂化数均为2,硝酸的溶剂化数为1。还对温度对萃取的影响,铀、钍的反萃及三相的形成进行了研究,计算了萃取平衡常数和铀、钍的△H值。     

螯合剂与牛血清白蛋白竞争钍作用的研究

用凝胶色谱法对１４个螯合剂（羧氨酸类－ＴＴＨＡ、ＤＴＰＡ、ＥＤＴＡ；取代苯酚类－８ｌｌ、８１０２、７６０１、７６０２、７６０３、７６１６、７７１１、７７２４、７８０３、７８０４、８３０７）与牛血清白蛋白对钍的络合竞争能力进行研究，以描述竞争能力的参数Ｆ值作为判断指标。结果表明，ＴＴＨＡ、８ｌｌ、８１０２３个螯合剂对钍有较强的竞争能力，而７８０４、ＥＤＴＡ的竞争能力最差。测得的各螯合剂竞争能力强弱次序与以往的动物实验结果基本一致。说明此方法可作为体外筛选促排钍药物的方法。     

1,10-双(1′-苯基-3′-甲基-5′-氧代吡唑-4′-基)癸二酮-[1,10]萃取钍的研究

1,10-双(1′-苯基-3′-甲基-5′-氧代吡唑-4′-基)癸二酮-[1,10](以下简称H_2A)是最近合成的一种β-双酮螯合剂,它比HPMBP多一倍螯合功能团,在适当的条件下能与钍(Ⅳ)生成比较稳定的螯合物,并能被氯仿萃取。为此,我们研究了H_2A与钍(Ⅳ)的萃取行为,也试验了Th(Ⅳ)与U(Ⅵ),La(Ⅲ),Ce(Ⅲ),Pr(Ⅲ),Nd(Ⅲ),Sm(Ⅲ),Eu(Ⅲ),Tb(Ⅲ),Er(Ⅲ)和Yb(Ⅲ)萃取分离的可能性。     

燃煤电厂气载排出物中天然铀、钍所致周围空气污染浓度及地面沉积量的分布

对苏州某大型电厂燃煤及烟道灰中天然铀、钍含量进行了测定;分析了1980年全年的逐时气象资料,采用 P-T 法进行天气稳定度分类,计算了风向、稳定度、风速联合频率(?)及降雨的风向频率 f_(Rijk);估算了该厂气载排出物(烟尘)造成的厂区周围60km 半径范围内近地面空气中天然铀、钍的污染浓度,地面沉积量及其分布。计算中对高空风速、烟云抬升、静风及沉积(尤其是降雨引起的湿沉积)造成的空气中污染物浓度的降低作了修正。估算结果表明,空气中铀、钍最大年平均污染浓度出现在 SE 方位离源 lkm 处,其值分别为0.195、0.345ng·m~(-3);在距烟囱10km半径范围内,地面沉积量主要来自降雨冲洗造成的湿沉积,10km 以外则应同时考虑干沉积的贡献。     

Burnup optimization of once-through molten salt reactors using enriched uranium and thorium

The advantages of once-through molten salt reactors include readily available fuel,low nuclear proliferation risk,and low technical difficulty.It is potentially the most easily commercialized fuel cycle mode for molten salt reactors.However,there are some problems in the parameter selection of once-through molten salt reactors,and the relevant burnup optimization work requires further analysis.This study examined once-through graphitemoderated molten salt reactor using enriched uranium and thori...     

Risk of malignancies in relation to terrestrial gamma radiation in a Swedish population cohort

Results of epidemiological studies on terrestrial gamma radiation (TGR) and related malignancies have not been consistent. This study is a thorough examination of this relationship. Records on all individuals living in two Swedish counties in 1973, along with their annual dwelling coordinates during the 28-year follow-up period, were retrieved from the National Archives and Statistics Sweden. We used Geographical Information System (GIS) to match the individuals' dwelling coordinates annually to the TGR given in 200 × 200 m grids produced by the Geological Survey of Sweden. Cases of malignancies and deaths were retrieved from the Swedish Cancer Register. During the follow-up period 61,503 incident cases were included in the analyses and in total 11 million person-years were recorded. Cox regression was used both in a linear continuous model and analyses of six exposure categories. Adjustments were made for sex, age, and population density. The hazard ratio (HR) per 100 nanoGray/hour (nGy/h) was significantly increased for total malignancies and for several sites; however, contrary to expectations, an obvious and anticipated linear exposure-response relationship could not be identified. With the lowest exposure category (0-60 nGy/h) as reference, a statistically significantly increased HR for total malignancies was seen in all exposure categories, except in the highest category 96-366 nGy/h. For breast cancer, thyroid cancer and leukaemia an obvious exposure-response could not be seen.     

Thorium and rare earth recovery in Canada: the first 30 years

Abstract

Pioneering methods to recover thorium and rare earths as byproducts of uranium recovery were developed and applied in Elliot Lake, Ontario, during the 1960s. The district became a major supplier of these key elements from about 1960 until 1990 and at one stage supplied much of the world’s thorium and perhaps one third of its yttrium. This paper reviews these early thorium rare earth operations.

On a développé et appliqué des méthodes innovatrices pour la récupération du thorium et des terres rares comme sous-produits de la récupération de l’uranium, à Elliot Lake, en Ontario, dans les années 60. Le district devint un fournisseur majeur de ces éléments clés à partir d’environ 1960 jusqu’en 1990 et, à une certaine période, fournissait la plupart du thorium mondial et peut-être un tiers de son yttrium. Cet article examine ces premières opérations de thorium et de terre rare.