Investigations and Design Studies on the Ultra High Flux Research Reactor

超高通量研究堆（Advanced Neturon Source，ANS）的基本设计研究正在日本大学研究人员和橡树岭国立核动力学研究所（美方的主办机构）之间的研究人员级合作下进行。这项研究的目标是前所未有的10^<16>n/cm^2秒的高通量。联合研究正在审查各种科学和工程问题。(1)对于堆芯冷却，经过一定的检验后，推荐使用甘比尔公式。然而，根据ORNL计划中的额外冷却实验的结果，一些改进是必要的。在系统考虑燃料相关制造误差的情况下，进行了热点估计的基础研究。(2)用Mante-Carlo方法计算了实验管的反应性效应和中子束流性能。为了加快计算速度，需要对基于微扰概念的程序作一些改进。(3)研究了一次冷却事故的瞬态现象。结果表明，向下流动冷却比向上流动冷却需要更长的自然循环前的紧急堆芯冷却时间。重新将ANS的参考岩心改为偏置型，保留了原有的分裂柱系统，所有的研究工作都将在新的偏置型岩心上进行。

Basic design studies of the Ultra-High-Flux Research Reactor (Advanced Neturon Source, ANS) are being carried out between Japanese university researchers and Oak Ridge National Laboratry (host institute of the US side) under the researcher level ' s cooperation. The target of the study is the unprecedented high flux of 10^<16> n/cm^2 sec. Various scientific and engineering problems are being examined by the joint study.(1) For core cooling, the Gambill ' s formula has been recommended after certain examinations. However, someimprovements should be necessary depending on the results of additional cooling experiments which are under planning at ORNL. Basic study for hot spot estimations under systematic considerations about correlated manufacturing errors of the fuel was carried out.(2) Reactivity effect and neutron beam performances of experimental tubes are examined by Mante-Carlo caluclation. Some improvements of the code based on perturbation concept is required for acceleration of the calculations.(3) Transient phenomena about the primary cooling accident was studied. It was found that longer time of emergency core cooling before natural circulation was necessary for downward flow cooling than upward cooling. Recentry the reference core for the ANS has been modified to off-set type while split cylindrical system is maintained heredfter, all studies will be carried out on the new refernce core.