Environmental radioactivity level at a mantle factory in eastern Zhejiang

The Y radiation level, alpha potential energy of thoron and alpha surface contamination level at a mantle factory in the east of Zhejiang Province are reported. The measured results show that the additional annual effective dose equivalent absorbed by the worker in some workshops of the factory was higher than 15 mSv-management limit. The alpha surface contamination on the workers' hands in some workshops was 10 times more than the management limit of National Standard (0.04 Bq/cm2). The mantle factory s main danger to body was internal irradiation of a rays from thoron aerosol.     

The ternary thorium aluminium carbides Th2Al2C3 and ThAl4C4

The title compounds were prepared by are-melting cold-pressed pellets of the elemental components with subsequent annealing at 900°C. Th₂Al₂C₃ crystallizes orthorhombic: Pnnm, a = 540.6(1) pm, B = 1155.6(2) pm, C =3 52.01(6) pm, Z = 2. The structure was determined from powder diffractometer data using the Rietveld method: R_F = 0.039 for 42 structure factors and six variable positional parameters. The positions of the metal atoms correspond to those of the InS-type structure. The two different carbon atoms are in octahedral coordination formed by four thorium and two aluminium atoms. The hydrolysis of ThAl₄C₄ with diluted hydrochloric acid resulted in 74 wt.% methane, 12 wt.% ethane and ethylene and 14 wt.% saturated and unsaturated higher hydrocarbons. Nevertheless, the crystal structure determination from single-crystal X-ray data showed that there are only isolated carbon atoms in the solid: I4/m, a = 823.1(1) pm, C = 332.72(6) pm, Z = 2, R = 0.032 for 13 variable parameters and 372 structure factors. It is isotypic with UCr₄C₄. The carbon atoms are octahedrally coordinated by two thorium and four aluminium atoms.     

含钍铀的稀土矿中微量钪的测定

试验了在６％（Ｖ／Ｖ）ＨＣＩ中用铜铁试剂－氯仿除去大部分钍,在１０％ＨＣＩ（Ｖ／Ｖ）中用二苯胍－偶氮胂Ⅲ－正于醇除尽钍铀;ＰＭＢＰ－醋酸丁酯富集钪分稀土元素;最后用半二甲酚橙显色测定钪,摩尔吸光系数为３．４×＾４;本法具有比离子交换分离法快速,成本低,结果可靠,实用性强等优点。     

某稀土冶炼厂放射卫生现状调查

报道了对某稀土冶炼厂辐射环境和职业性查体调查结果。调查的主要内容有：环境放射性检测与评价,工人肺内钍沉积量测定及其对健康的影响。调查结果表明：该厂4个接尘车间属于放射性工作场所,9名接尘工人肺内钍沉积量超过1个调查水平（2．22Bq）,未发现接尘工人中出现尘肺,其外周血象和肝功能均未发现异常。     

P-350萃取色层法测定食品中微量钍

文献[1,2]曾报道了以国产胺类萃取剂 N-235为固定相的萃取色层分离法测定食品及天然水中微量铀、钍、镭。本文提出以中性膦类萃取剂甲基膦酸二甲庚脂(简称 P-350)作为固定相的萃取色层法,测定食品中微量钍。实验表明 P-350对铀、钍有良好的萃取选择性,并且由于其水溶性较小,而更适宜于作为萃取色层中的固定相。食品灰样经酸溶液浸取后,在2M HNO_3介质中流经色层柱,除去大部分杂质,然后以6M HCl 淋洗钍,即可用偶氮胂 III 比色测定。本方法简便,回收率高,选择性好。     

Plutonium management with thorium-based fuels and inert matrix fuels in thermal reactor systems

The plutonium that is produced by light water reactors worldwide is currently re-used to a limited extent. In the last century, the expected introduction of fast reactors and the associated need for large amounts of plutonium did not take place. The result is that worldwide a stockpile of excess plutonium has formed, which is the dominant contributor to the radiotoxicity of spent nuclear fuel for storage times from 10² to 10⁵ years. One option to reduce or stabilize the plutonium stockpile is to utilize this plutonium in advanced fuel types, such as thorium-based and inert matrix fuels. Because these fuels do not contain uranium, the plutonium consumption rate is very high. In this paper, the status of the fuel research and some recent developments are given.     

Preliminary study on feasibility of large and small water cooled thorium breeder reactor in equilibrium states

Fuel breeding is one of the essential performances for a self-sustaining reactor system which can maintains the fuel sustainability while the reactor produces energy and consumes the fissile materials during operation. Thorium cycle shows some advantageous on higher breeding characteristics in thermal neutron spectrum region as shown in the Shippingport reactor and molten salt breeder reactor (MSBR) project. In the present study, the feasibility of large and small water cooled thorium breeder reactors is investigated under equilibrium conditions where the reactors are fueled by ²³³U–Th oxide and they adopts light water coolant as moderator. The key properties such as required enrichment, breeding capability, and initial fissile inventory are evaluated. The conversion ratio and fissile inventory ratio (FIR) are used for evaluating breeding performance. The results show the feasibility of breeding for small and large reactors. The breeding performance increases with increasing power output and lower power density. The small reactor may achieve the breeding condition when the fuel pellets' power density of about 22.5 W/cm³ and burnup of about 20 GWd/t.     

偶氮氯膦pA分光光度法测定微量钍的研究

研究了偶氮氯膦 pA在酸性介质中 ,与钍离子形成络合物的最佳条件。络合物的组成比为偶氮氯膦 pA :Th4+=2∶1 ,其表观摩尔吸光系数为 ε71 0 =6.6× 1 0 4 ,钍含量在 0.0～ 1 3.0 μg/1 0mL范围内符合比尔定律。由此建立了微量钍的一种分光光度分析法。该法简便快速 ,灵敏度高 ,选择性好 ,常温下可直接于水相中进行测定 ,结果满意。     

Actinide breeding and reactivity variation in a thermal spectrum ADSR – Part 2: Enhanced sustainability in the thermal spectrum

For more sustainable nuclear power to be realised improvements will be needed in the efficiency with which energy is derived from the remaining finite uranium reserves, while at the same time delivering reductions in the quantities of long-lived actinides contained within the spent fuel. The use of fast reactors to achieve this is the subject of renewed interest due to their beneficial capability to both burn and breed transuranic actinides. However, fast reactors have a mixed track record and have never been deployed in significant numbers despite considerable investment in the development of the technology over many years. In light of these difficulties, future advances in nuclear technology may be more readily realised through enhancements to the existing, well proven light water reactor (LWR) technology base.     

Separation of uranium and thorium from rare earths for rare earth production – A review

Rare earths play critical roles in the applications of advanced materials. Recently, the recovery of rare earths from a variety of resources has gained much interest. Radioactive elements of uranium and thorium are usually associated with rare earth deposits. The separation of uranium and thorium from rare earths is often a big concern in rare earth industry in order to reasonably manage the radioactive nuclides. This paper reviews the technologies used for separating uranium and thorium from rare earths in rare earth production, particularly in China. Some potentially applicable methods, such as precipitation and solvent extraction for the separation of uranium and thorium from rare earths in different media were also reviewed.