Thermoluminescence measurements of neutron streaming through JET Torus Hall ducts

Thermoluminescence detectors (TLD) were used for dose measurements at JET. Several hundreds of LiF detectors of various types, standard LiF:Mg,Ti and highly sensitive LiF:Mg,Cu,P were produced. LiF detectors consisting of natural lithium are sensitive to slow neutrons, their response to neutrons being enhanced by ⁶Li-enriched lithium or suppressed by using lithium consisting entirely of ⁷Li. Pairs of ⁶LiF/⁷LiF detectors allow distinguishing between neutron/non-neutron components of a radiation field. For detection of neutrons of higher energy, polyethylene (PE-300) moderators were used. TLDs, located in the centre of cylindrical moderators, were installed at eleven positions in the JET hall and the hall labyrinth in July 2012, and exposure took place during the last two weeks of the experimental campaign. Measurements of the gamma dose were obtained for all positions over a range of about five orders of magnitude variation. As the TLDs were also calibrated in a thermal neutron field, the neutron fluence at the experimental position could be derived. The experimental results are compared with calculations using the MCNP code. The results confirm that the TLD technology can be usefully applied to measurements of neutron streaming through JET Torus Hall ducts.     

d-T源中子照相装置慢化准直系统初步设计

慢化体准直器是热中子照相装置的关键组件之一,利用铅、铍、石墨等为慢化体的材料,对d-T反应中子源中子照相装置的慢化准直系统进行设计.采用MCNP程序模拟d-T反应快中子在慢化体内的中子慢化输运过程,通过计算得到了满足热中子照相的慢化准直系统的设计方案,给出了经慢化后的中子束各项物理参数.     

关于深燃耗堆芯的反应性测量

介绍了在实验性PWR堆上完成的深燃耗条件下测量反应性概况。用实验结论剖析了在国外核电站堆芯上应用噪声分析法对慢化剂温度系数作全燃耗期监测研究中出现的测量结果与常规方法相差2～5倍的现象。从测量公式和堆芯扰动模型图入手所作的分析结果说明,没有消除随燃耗不断增长的强自发裂变中子源干扰是产生差异的根本原因。事实说明:在多种噪声分析技术中,只有能够清除自发裂变中子源干扰的方法才能成功地应用于燃耗后堆芯的反应性测量。     

CANDU6慢化剂系统丧失冷却情况下的温度分析

压力管卧式重水反应堆(CANDU6)具有相互独立的冷却剂系统和慢化剂系统。慢化剂系统将堆芯高能裂变中子慢化到能维持持续裂变所需的热中子水平,并将慢化中子过程中产生的热量带出。在反应堆大修期间,需要对再循环冷却水系统(RCW)进行检修,则需要并投入其备用系统,但是RCW备用系统仅对反应堆冷却剂系统进行冷却,不提供慢化剂系统热交换器冷却水。所以在RCW备用系统投入的情况下,慢化剂系统丧失冷却。为判断在此情况下慢化剂的温度变化情况,本文对CANDU6大修期间慢化剂系统丧失冷却情况下的温度变化进行分析并与试验结果进行比较,评估是否会由于温度过高而导致系统失效。     

Predicting outcome in computerized cognitive behavioral therapy for depression in primary care: A randomized trial.

Objective: To explore pretreatment and short-term improvement variables as potential moderators and predictors of 12-month follow-up outcome of unsupported online computerized cognitive behavioral therapy (CCBT), usual care, and CCBT combined with usual care for depression. Method: Three hundred and three depressed patients were randomly allocated to (a) unsupported online CCBT, (b) treatment as usual (TAU), or (c) CCBT and TAU combined (CCBT&TAU). Potential predictors and moderators were demographic, clinical, cognitive, and short-term improvement variables. Outcomes were the Beck Depression Inventory–II score at 12 months of follow-up and reliable change. Results: Those with higher levels of extreme (positive) responding had a better outcome in CCBT compared with TAU, whereas those having a parental psychiatric history or a major depressive disorder diagnosis had a better outcome in CCBT&TAU compared with TAU. Predictors regardless of treatment type included current employment, low pretreatment illness severity, and short-term improvement on clinical variables. Conclusions: Optimistic patients, holding approach-oriented coping strategies, might benefit most from CCBT, whereas CCBT&TAU might be the most suitable option for those with more severe vulnerability characteristics. Those with the least impairment improve the most, regardless of treatment type. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Emotional Expression in Cyberspace: Searching for Moderators of the Pennebaker Disclosure Effect via E-Mail.

Research has shown that writing about emotional topics can positively influence physical and mental health. The current study tested the efficacy of an e-mail-based writing treatment and shows how such an implementation can aid in the search for moderators. Participants (N = 546) were randomly assigned to either a long- or short-interval traumatic writing condition or to a nonemotional writing control condition. In contrast to previous disclosure research, participants received and submitted their writing responses via e-mail. Health outcomes were assessed weekly for 5 weeks after treatment and were reported at the conclusion of the study. Results supported the effectiveness of an e-mail-based writing treatment in producing positive health outcomes and successfully identified several moderators of the writing treatment effect. The moderators implicated varied depending on the nature of the health outcome assessment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

CeO2对ZrH1.8表面微弧氧化复合陶瓷层结构的影响

目的利用微弧氧化表面处理技术,通过改变电解液成分,在ZrH_(1.8)表面原位制得一层致密的复合陶瓷层。方法通过在电解液中添加CeO_2颗粒,采用恒压模式对氢化锆(ZrH_(1.8))表面进行微弧氧化处理,利用扫描电子显微镜(SEM)、X射线衍射仪(XRD)、涂层测厚仪、涂层附着力自动划痕仪,分析陶瓷层表面和截面形貌、相结构、厚度及其与基体的结合力,通过Archimedes排水法对所制备陶瓷层的致密性进行定量分析。结果 CeO_2颗粒的添加有利于陶瓷层的生长,与不添加CeO_2颗粒所制得的陶瓷层相比,加入CeO_2后,陶瓷层的厚度有所增加,陶瓷层与基体的结合力由81 N增大至104 N。XRD分析表明,陶瓷层中出现CeO_2特征峰,可知CeO_2在微弧氧化过程中成功地吸附在陶瓷层表面。不添加CeO_2时,陶瓷层的孔隙率为14.22%;添加CeO_2后,陶瓷层的孔隙率降低至5.79%。结论 CeO_2颗粒的加入可有效提高基体ZrH_(1.8)与陶瓷层的结合力,降低了陶瓷层的孔隙率,使氢化锆表面微弧氧化陶瓷层的致密性得到改善。     

Investigation on Criticality and Infinite Multiplication Factor of High Conversion Light Water Reactor Using Zone-Type FCA-HCLWR Core Fueled with Enriched Uranium

—A series of reactor physics experiments have been carried out at the FCA to examine the availability of the nuclear data and computational method currently employed to evaluate the nuclear characteristics of the High Conversion Light Water Reactor. Experimental results of the effective and infinite multiplication factors k_eff and k_∞ are compared with the calculated ones for three zone-type FCA-HCLWR cores fueled with enriched uranium. The calculated k_eff and k_∞ values with use of the SRAC system and the cross section set based on the JENDL-2 data file show a good agreement with the measured ones. The calculated-to-experimental (C/E) values for k_eff and k_∞ do not depend on the cell parameters such as the fuel enrichment, the moderator voidage state and the moderator-to-fuel volume ratio, and these values are similar with each other There is also no inconsistency between the C/E values for k_eff and k_∞ : The average C/E values are 989 and 0 988 for k_eff and k_∞ respectively     

耦合慢化器结构多方案强度设计

用I-DEAS系统对散裂中子源耦合液氢慢化器在不同结构形式及工艺条件下的强度进行计算。通过对应力分布及变形分析,确定慢化器焊缝位置及止口形式,确定合理的慢化器结构参数。为慢化器结构设计及加工提供依据。     

Optimized design for time-of-flight total neutron scattering instrumentation using Monte Carlo simulations with application for the characterization of disordered macromolecules

Abstract

A time-of-flight neutron total scattering instrument for the China Spallation Neutron Source (CSNS) was designed. The instrument is designed for disordered macromolecular systems with characteristic lengths below 10?nm. The coupled hydrogen moderator of CSNS was selected to ensure the favorable statistics at the smallest scattering vector of 0.01?Å^?1. The optics and geometry of the instrument were optimized to cover a wide range of scattering vectors from 0.01 to 70?Å^?1. The performance of the instrument was examined using a series of Monte Carlo simulations, which demonstrate that the flux on the sample, the resolution, and the range of the scattering vectors are comparable to those of other advanced neutron total instruments. Finally, a virtual experiment was performed with silica powder. The resulting scattering pattern is consistent with both the numeric calculation and the estimated resolution of the instrument. The designed total scattering instrument at CSNS allows the simultaneous observation of both atomic and nanometer scale structures, having the potential to become a powerful tool for studying the structure of disordered materials in the fields of polymers, biology, and condensed matter physics.