Measurements of the elastic scattering cross sections for proton on T, He

The cross sections for the elastic scattering of protons from tritium at 151° and from helium at 155° angles in the laboratory frame, over the energy range of 1.2-3.4 MeV, have been measured in the present work, as a supplement to previous cross section measurements determined at different scattering angles recently. The currently measured cross section data are compared to data available in literature. The cross section enhancement was also investigated for both reactions. It was found that over the whole measured energy range, the elastic cross section for protons on tritium increases linearly with energy and is about 1000 times greater than the Rutherford cross section at 3.4 MeV. On the other hand, in the case of the elastic scattering of protons from helium, the cross section below 2.3 MeV increases almost linearly, and reaches a maximum of about 300 mb/str at the energy of 2.4 MeV for the scattering angle of 165°, and then, after this energy, it keeps oscillating around the maximum.     

堆芯核设计程序CYCAS少群截面模型开发

少群截面模型为堆芯三维扩散计算提供实时的节块均匀少群截面,是堆芯计算程序的关键模型之一。CYCAS程序是上海核工程研究设计院最新开发的堆芯三维核设计程序。本文在详细解析影响节块截面的各种因素的基础上,提出应用于CYCAS程序的少群截面的模型。该模型采用能谱修正方法处理由于能谱变化所引入的二次效应,采用微观燃耗修正方法处理燃耗历史效应。单组件和AP1000核电厂的数值验证计算表明,该模型具有很高的计算精度。     

A theoretical study on different cluster configurations of the 9Be nucleus by using a simple cluster model

In this study,a comprehensive investigation on different cluster configurations of the ~9Be nucleus is performed with a simple cluster approach.With this goal,the elastic scattering angular distributions of ~9Be by ~(27)A1,~(28)Si,~(64)Zn,~(144)Sm,~(208)Pb,and ~(209)Bi target nuclei are reanalyzed for α + α + n,d + ~7Li,~3H + ~6Li,~3He + ~6He and n + ~8Be cluster configurations of the ~9Be projectile within the framework of the optical model.The theoretical results are compared with each other as well as the experimental data.The results provide an opportunity for a test of different cluster configurations in explaining the elastic scattering of~9Be nucleus.     

Development of a reference database for Ion Beam Analysis and future perspectives

Ion Beam Analysis (IBA) is a set of material characterization techniques using energetic ion beams. IBA provides information about composition and the depth profile of elements in the near-surface layers of a sample, from the energy spectra of backscattered primary particles, recoils, nuclear reaction products or emitted γ-radiation. All IBA methods presuppose knowledge of the differential cross-section data however, only for strict Rutherford scattering is the cross-section known exactly. In order to address the data needs of the IBA community, the IAEA initiated the Coordinated Research Project (CRP) “Development of a Reference Database for Ion Beam Analysis” in 2005 which will conclude in 2010. The project focuses on the measurement, assessment, evaluation and benchmarking of elastic scattering and reaction cross sections. Data measured in this work have been incorporated in the IBANDL database (http://www-nds.iaea.org/ibandl/), whereas the evaluated cross-sections (calculated from the fit to the data of a nuclear model) are made available to the community through the on-line calculator SigmaCalc (http://www-nds.iaea.org/sigmacalc/).A summary of the results of the CRP activity is presented, and ways to further develop nuclear data for IBA are indicated. In particular, a newly proposed CRP devoted to particle induced gamma-ray emission is described.     

Development and verification of a new nuclear data processing system FRENDY

Japan Atomic Energy Agency developed the new nuclear data processing system FRom Evaluated Nuclear Data librarY to any application (FRENDY) in order to solve the problems of the current widely used nuclear data processing systems and process the new evaluated nuclear data file. Verification of FRENDY was carried out by three steps, i.e. verification of each function, comparison of the results, and comparison of the k_eff values for the 79 benchmark experiments in the ICSBEP handbook using cross section data library processed by FRENDY with those by NJOY99. These results verified that FRENDY generates the ACE (A Compact ENDF) file correctly.     

三种解谱算法求解中子能谱的解谱效果比较

使用多球谱仪测量中子能谱时,需要使用"少道"解谱算法。为此,本文分别将迭代算法、蒙卡算法和遗传算法应用到中子能谱解谱中,通过MCNP模拟几种辐射防护常见的中子能谱,模拟得到探测器在各个球中的计数,然后使用迭代算法、蒙卡算法和遗传算法进行解谱,并对三种解谱算法的解谱效果进行比较。结果显示,三种算法均能够很好的完成解谱,且给出的中子注量、周围剂量当量和平均能量与参考值符合的也较好。另外,在典型的中子辐射场,三种算法的使用条件不同,可相互配合,较好的给出解谱结果。     

用屏栅电离室测量~6Li(n,t)~4He反应微分截面

用屏栅电离室对 3.6 7MeV与 4 .4 2MeV中子6Li(n ,t) 4He反应微分截面进行了测量。利用氘气体靶通过D(d ,n) 3 He反应产生中子 ,用BF3 和液闪探测器 (NE2 13)进行相对中子通量监测 ,绝对中子通量用2 3 8U(n ,f)与H(n ,p)反应来刻度。测量结果表明 ,氚的质心系微分截面在中子能量为 3.6 7MeV时很接近 90°对称 ,而到 4 .4 2MeV时则明显前倾     

遗传算法在高通量工程试验堆燃料管理优化中的应用

建立了基于遗传算法的高通量工程试验堆(HFETR)堆内燃料管理优化模型。根据HFETR的实际情况，提出了基于组件位置的二进制编码/解码技术。研究了不同选择策略对算法性能的影响，探讨了遗传算法和专家经验的结合，吸收了自适应遗传算法的思想，得到了可直接应用于HFETR的优化换料方案。     

Benchmark Model of Critical Experiment at TCA for Integral Evaluation of Fission Product Nuclide Cross Sections

Benchmark models of the critical experiments which measured reactivity effects of main fission product elements (Rh, Cs, Nd, Sm, Eu, and Gd) and of an important burnable poison element, erbium, were presented. These elements were dissolved in a vessel which was inserted into the central region of a fuel rod array of TCA (Tank-Type Critical Assembly). The atomic number densities of aqueous solutions in the vessel were calculated. Using these number densities, criticality calculations with MCNP 4A, TWOTRAN code, and JENDL-3.2 cross section library were performed for these experiments.     

Coupled-Channels Analysis of Nucleon Interaction Data of 28'30Si up to 200 MeV Based on the Soft Rotator Model

A consistent analysis for nuclear level structure and nucleon scattering data up to 200 MeV was performed for sd-shell nuclei, ^28,30Si, using a unified framework of soft-rotator model and coupled-channels approach. The ^28,30Si were assumed to be deformed nuclei having oblate shapes. The soft-rotator model parameters were determined so as to reproduce measured collective levels of ^28,30Si up to an excitation energy of around 10 MeV. The relativistic kinematics and global optical potential form were taken into account in the coupled-channels optical model analysis, and the optical model parameters were derived. The calculation showed good agreement with experimental data for both collective levels and nucleon interaction data—neutron total cross sections, proton reaction cross sections, and nucleon scattering angular distributions.     

Development of a new approach,evolutionary harmony search algorithm,for the LPO problem

This paper proposes a new variant of harmony search (HS) algorithm i.e. evolutionary harmony search (EHS), for exploiting in the loading pattern optimization (LPO) problem. The main innovations of EHS are the consideration of current best harmony vector in creating the new solution vector in any iteration and applying a pitch adjustment approach using a mutation strategy borrowed from the realm of the differential evolution (DE) algorithms, both with dynamic probabilities. Reactor core pattern optimization has been done using EHS for two test cases including KWU PWR and VVER-440. In order to represent the EHS capability to gain improved results in the LPO problem, a comparison is performed between results of EHS and a recent developed HS algorithm i.e. self-adaptive global best harmony search (SGHS). Numerical results show a major and distinctive enhancement of the proposed approach, EHS, in obtaining convergent results in comparison to SGHS approach. As a result, I can recommend the checking of EHS performance in other optimization problems.     

Comparison of Group Constants Using Single-and Multi-Level Formulas for the Resolved Resonance Region of Uranium-235 and Uranium-233

Using the single-level and the Adler-Adler multi-level resonance formulas for ²³⁵U, whose parameters were derived by fitting to common experimental data, group constants were obtained for the energy region from 59.8 to 0.215 eV, having the same group structure as the 70 group JAERI-FAST set.

It was found that use of the multi-level formula is preferable to the single-level alternative, the former being able to reproduce the experimental data more accurately than the latter. The resulting difference in the values of the group constants amounted to about 40% for some groups.

The group constants of ²³³U, determined by means of multi-level formula are also presented for the energy region from 36.0 to 0.215 eV.     

Using a modified CINDER90 routine in MCNPX 2.6.0 for the prediction of helium production in minor actinide targets

Fast reactors containing heterogeneous minor actinide (MA) target rods are now being modeled. When studying transmutation in these rods, helium production from α-decay must be considered since it is produced in substantial quantities. This research utilized an innovative method to calculate gas production by modifying the CINDER90 depletion code used by MCNPX 2.6.0 to include helium production from α-decay. The modified CINDER90 code was verified using the ORIGEN-ARP module of SCALE6. It was tested using the Sodium-Cooled Heterogeneous Innovative Burner Reactor model created at the University of South Carolina. It is recommended that the modified version of the cinder.dat file be distributed in subsequent MCNPX 2.6.0 releases for use in fast reactor calculations using heterogeneous MA target rods since it includes helium production otherwise not available from the current version.     

Development of Three-Dimensional Numerical Model for 222Rn and Its Decay Products Coupled with a Mesoscale Meteorological Model II. Numerical Analysis on the Increase in Gamma Dose Rate Observed in the Coastal Area of Fukushima Prefecture

A three-dimensional Eulerian numerical model for ²²²Rn and its decay products coupled with a mesoscale meteorological model, MM5-TMNR, is applied to investigate the mechanism of the naturally induced increase in gamma dose rate observed at the coastal area of Fukushima prefecture in October 2002. The results obtained by MM5-TMNR are verified by comparisons with observed wind, precipitation and gamma dose rate to be adequate for examining the mechanism. The unusual increase in gamma dose rate is observed by the combination of the synoptic-scale (about 2000 to 5000 km horizontally) transport of natural radionuclides due to the inflow of cold air mass from the Asian Continent and the meso-_-scale (about 20 to 200 km horizontally) precipitation process within the coastal area of Fukushima prefecture. The contribution rate of natural radionuclides from the Asian Continent to the increase in gamma dose rateis estimated to be more than 60%.