人骨骼中~(228)Th、~(230)Th和~(232)Th含量的同时测定

本文介绍了用α谱仪同时测定人骨骼中~(228)Th、~(230)Th和~(232)Th含量的方法。样品用浓 HNO_3和 H_2O_3湿灰化,草酸钙共沉淀载带、CL-5208萃淋树脂和743阳离子交换树脂联合分离后,电沉积制源,在低温半导体α谱仪上测量。该方法对~(234)Th的全程回收率为95.0±1.7%,对铀和镭的去污系数分别为6.3×10~4和1.5×10~3,对~(228)Th、~(230)Th、~(232)Th 的探测下限分别为0.432、0.135和0.108Bq/kg(鲜重)。     

Investigation of the MSFR core physics and fuel cycle characteristics

The adoption of Th fuel in fast reactors is being reconsidered due to the potential favorable impact on actinide waste management and resource availability. A closed Th cycle leads to an actinide inventory with lower radiotoxicity and heat load for the first several thousands of years. Due to the typically low TRansUranic (TRU) Conversion Ratio (CR), Th can also be advantageous to expedite the consumption of legacy TRU. One of the main obstacles to the implementation of Th is the highly radioactive recycled fuel which requires remote handling under heavy shielding, inevitably penalizing economics and challenging conventional pin-based fuel manufacturing. From this perspective, the development of liquid-fuelled reactors, with Molten Salt Reactors regarded as the most promising, appears particularly attractive as fuel handling would be greatly simplified. The present paper investigates the fuel cycle performances of the reference GEN-IV Molten Salt Fast Reactor (MSFR) in terms of isotope evolution, radiotoxicity generation and safety-related parameters. Similarly to most MSR concepts proposed in the past, the MSFR is based on the fluoride molten salt technology, but it features the novelty of a fast neutron spectrum. Calculations are performed using state-of-the-art equilibrium-cycle methodologies, i.e., the ERANOS-based EQL3D procedure developed at the Paul Scherrer Institut and extended to the simulation of the MSFR. Selected results have been benchmarked with the Monte Carlo code PSG2/SERPENT. These results have also been used for the assessment of a diffusion module based on the COMSOL multi-physics toolkit, which is the subject of current studies aimed at efficiently simulating the peculiar MSFR transient behavior.     

Spatial distribution of thorium fission rate in a fast spallation and fission neutron field: An experimental and Monte Carlo study

The Energy plus Transmutation (EpT) set-up of the Joint Institute for Nuclear Research (JINR), Dubna, Russia is composed of a lead spallation target surrounded by a blanket of natural uranium. The resultant neutron spectrum is a combination of spallation and fission spectra, modified by a reflective external layer of polyethylene and an internal absorbing layer of cadmium. The EpT set-up was irradiated with a beam of 4 GeV deuterons from the Nuclotron Accelerator at JINR. The spatial distribution of thorium fission rate within the assembly was determined experimentally, using a fission track detector technique, and compared with Monte Carlo predictions of the MCNPX code. Contributions of neutrons, protons, deuterons, photons and pions to total fission were taken into account. Close agreement between the experimental and calculated results was found.     

Criticality of the thorium burnup in equilibrium state

The effective neutron multiplication factor (k_eff) as a function of burnup for different volume coolant (CoR) and fuel (FR) to cell ratio is presented. Additionally the Conversion Ratio (CR) of Th-232 to U-233, concentration of U-233, fissile and fission products calculation as a function of burnup are presented. The assembly is a critical reactor which makes volumes of coolant and fuel changes possible. In addition, an analytical model of calculation of k_eff as a function of U-233 and a poison concentration in equilibrium state are presented. One can achieve the criticality of Thorium Breeder Reactor (TBR) for enough high average neutron energy which one can obtain in Fast Breeder Reactor (FBR) only. The maximal value of CR and burnup for case of k_eff ≥ 1 achieves 1.4 and 360 GWd/MTU, correspondently. The calculations were done with a MCNPX 2.7 code using F₂Be, Na and Pb coolants.     

提高钍萃取率和反萃取率的研究

用Ｐ３５０为萃取剂，对萃余水相（钍渣盐酸分解液经ＴＢＰ萃取铀、铁后的溶液）中的钍进行了提高萃取率和反萃取率的研究。结果表明，在萃取料液中补加适量ＨＮＯ＿３，增加ＮＨ＿４ＮＯ＿３用量，可大幅度提高钍的萃取率；加适量氨水于水中作反萃取剂，可提高钍的反萃取率。     

TACR排管容器研究中多孔介质法的应用

以钍基先进重水堆(TACR:Thorium Based Advanced CANDU Reactor) 慢化剂系统排管容器作为研究对象,提出了一种适用于计算排管容器内流场和温度场的非结构网格多孔介质方法,并将其计算结果与精细数值计算法所获得的结果进行了比较,二者符合较好,由此验证了其方法与计算结果的正确性.     

TACR压力管与排管间辐射换热分析

辐射换热是钍基先进CANDU型反应堆(TACR)压力管和排管间换热的主要途径.本文以灰体辐射模型和电网络分析方法为基础建立了TACR压力管和排管间辐射换热的计算模型,利用该模型计算了给定温度边界和热流密度边界的情况下,压力管和排管间的辐射换热能力.计算结果表明,该模型可以用于TACR压力管和排管间辐射换热能力的计算.     

Extraction of U（VI） and Th（IV） with a novel extractant N,N‘—tetrahexylmalonamide （THMA） in toluene

The dependence of THMA extraction behaviour for U(VI) and Th(IV) on nitric acid concentration,THMA concentratioin and molecular structure of extracted complex has been studied.For nitric acid solutions of 3.0 mol/L a coordinative mechanism may possibly dominate in the extraction of metal catioins,The complex composition of UO2(NO3)2(THMA)2,Th(NO3)4(THMA)2 and Th(NO3)4(THMA03 are proved.     

Separation of Th~(4 ) and RE~(3 ) with Hollow Fiber Extraction

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