Np,Am, Cm utilization in a nuclear power reactor

The utilization (transmutation using the released energy) of Np, Am, and Cm in a specialized VVER-type reactor operating power 1000 MW(e) is studied by computational means. Five successive reactor runs, where the fuel elements contain Np, Am, Cm, and enriched uranium, are studied. It is shown that Np, Am, and Cm produced by several VVER-1000 reactors can be utilized in one run (900 days) of a specialized reactor without any technological and structural changes. Up to 4% of the reactor power comes from the fission of these radionuclides.     

244Cm Transmutation in Accelerator-Driven System

Mixed oxide (MOX) fueled LWRs are characterized by enhanced accumulation of curium isotopes compared to uranium fueled LWRs. Toxicity of relatively short-lived isotope ²⁴⁴Cm (T ₁/2=18 yr) appears to be dominant in transuranics discharge. The present paper deals with analysis of the scientific feasibility to transmute ²⁴⁴Cm. Liquid bismuth-curium core operated in a subcritical mode with neutron support from accelerator is proposed to provide transmutation rate through fissioning that exceeds the rate of natural decay by one order of magnitude. Beam current in the range 30–40 mA is required to drive the core. One accelerator-driven transmutor could solve the problem of curium accumulation in a large-scale nuclear energy system based on MOX fueled LWRs.     

Heterogeneous Transmutation of Am, Cm, and Np in a BREST Core

The effect of heterogeneous (in individual units) transmutation of Am, Cm, and Np on the radiation characteristics of fuel is examined. For heterogeneous transmutation of Am, Cm, and Np in individual fuel elements containing nitrides, the radiation characteristics and energy release increase substantially compared with fresh homogeneous fuel elements. Heterogeneous transmutation is dangerous from the standpoint of nonproliferation of fissioning materials because of the low critical mass of the main nuclides – ²³⁹Np and americium isotopes. 2 tables, 4 references.     

Np,Am, Cm transmutation efficiency parameters taking account of neutron reaction rates

Np, Am, and Cm transmutation efficiency parameters, taking account of the neutron reaction rates on all transuranium isotopes in all transformation chains initiated by introducing Np, Am, and Cm, are proposed for specialized transmutation facilities. These parameters can be helpful when comparing the efficiencies of different types of transmutation facilities and analyzing possible ways to increase the Np, Am, and Cm transmutation efficiency. The efficacy of including the parameters in the definition of transmutation efficiency is shown for a specialized transmutation facility. The possibility of evaluating the efficiency of Np, Am, and Cm transmutation in fast power reactors is examined taking account of the proposed parameters.     

环境水中U、Np、Pu、Am、Cm共浓集方法的研究

本文对大体积水样中 U、Np、Pu、Am、Cm 的共浓集方法进行了研究。采用了以氯化钙、氯化镁为载体,氢氧化物沉淀,载带浓集环境水中的 U、Np、Pu、Am,Cm。实验研究了 NaOH加入量,搅拌时间、水样体积对载带回收率的影响,单个核素及不同的混合核素的组合的载带回收率;以及 Np、Pu 的价态对载带回收率的影响和大体积下混合核素的回收率。该方法对大体积水样中这些锕系核素基本上能定量浓集(回收率92.7—96.8%);重复性好(标准误～3%)。实验证明 Np、Pu 的价态不影响载带回收率。该方法可用于厚样法测定这几个核素的“总α”以及薄源法测定超铀核素程序中。     

Neutron spectrum of248Cm spontaneous fission

V. G. Khlopin Radium Institute. Translated from Atomnaya Énergiya, Vol. 71, No. 6, pp. 566–568, December, 1991.     

HBTMPDTP对~(244)Cm萃取行为的研究

研究了二(2,4,4 三甲基戊基)二硫代膦酸(HBTMPDTP)从NaNO3 HNO3介质中萃取示踪量244Cm的行为。考察了搅拌时间、离子强度、平衡水相pH值、萃取剂浓度和温度等因素对萃取平衡的影响,给出了萃取反应方程式。计算得到萃取平衡常数Kex=10-7.84±0.09,萃取反应焓ΔH0=17.4kJ/mol,熵ΔS0=-95.2(J·mol)/K。     

Homogeneous Transmutation of Am, Cm, and Np in the Core of a BREST Reactor

The effect of homogeneous transmutation of Am, Cm, and Np in fuel on the radiation characteristics of the fuel is studied. It is shown that the holding period of the spent fuel influences the composition and mass of Am, Cm, and Np and the fuel quality. For homogeneous transmutation, increasing the Am, Cm, and Np fraction in the fresh fuel up to 5% has virtually no effect on the basic neutron-physical characteristics and safety of the reactor. The effect of adding to the main actinides particular elements from Am, Cm, and Np on the radiation characteristics of fresh and spent fuel with homogeneous transmutation is studied. 4 tables, 6 references.     

水样中Pu、Np、Am和Cm的联合快速分析方法

环境监测、辐射防护、核取证和核应急等领域对环境和生物样品中²³⁸Pu、²³⁹Pu、²⁴⁰Pu、²⁴¹Pu、²³⁷Np、²⁴¹Am、²⁴³Cm和²⁴⁴Cm测定的需求日渐增大。本研究提出一个自上而下串联TEVA树脂、UTEVA树脂和DGA树脂的联合、快速、可靠、可批量操作的分析方法,该方法首先通过水合氧化钛（HTO）共沉淀将待测核素从样品基质中分离,其后使用串联层析柱中的TEVA树脂柱分离纯化Pu与Np,DGA层析柱分离纯化Am与Cm。对于α放射性核素,通过CeF₃微沉淀法制备薄层α测量源,使用高分辨率α谱仪分别测量^239+240Pu、²³⁸Pu、²³⁷Np、²⁴¹Am与^243+244Cm;对于β放射性核素²⁴¹Pu,使用液体闪烁计数器测量。²³⁶Pu和²³⁴Am示踪表明该流程的化学回收率大于80%,加标实验结果表明期望值与测量值相吻合,证明了该方法的高可信度及稳定性。α谱仪测量48 h,最小可探测活度²⁴¹Am为0.40 mBq,^243+244Cm为0.33 mBq,²³⁸Pu为0.72 mBq,^239+240Pu为0.44 mBq,²³⁷Np为0.72 mBq。液闪计数器测量1 800 s,²⁴¹Pu的最小可探测活度为0.17 Bq。使用12孔真空盒同时制备12个样品,可加快制样时间,批次制样时间小于3 h,极大地降低了样品的使用量、制备时间和分析成本。