Introduction Outline of Facilities Publications

 JRR-4
  JRR-4 is a swimming pool-type reactor moderated and cooled with light water . The reactor core is established in “a core tank” in the reactor pool. The maximum thermal power of JRR-4 is 3,500 kW. The reactor power, operating time, and pattern are variable to meet the requirements set by users. The first purpose of JRR-4 was to carry out experiments for the Japanese nuclear ship “MUTSU,” but present purposes are medical irradiation (Boron Neutron Capture Therapy), activation analysis, production of semiconductor silicon, and education and training for engineers and researchers in various fields.

An outside view of the JRR-4 reactor building A cutaway view of the JRR-4 reactor building
An outside view of the JRR-4 reactor building A cutaway view of the JRR-4 reactor building


A top view of the JRR-4 reactor room A layout of the JRR-4 reactor core
A top view of the JRR-4 reactor room A layout of the JRR-4 reactor core



Purpose Medical Irradiation (Boron Neutron Capture Therapy ), Biological irradiation experiments, Activation analysis, Production of Radioisotopes, Education and Training, etc.
Type Light water moderated and cooled, swimming pool -type reactor with low-enriched uranium
Maximum thermal power: 3500(kW)
Maximum thermal neutron flux: 7×1017m-2s-1
Specifications of JRR-4



Link to JRR-4 homepage(in Japanese) JRR-4ホームページへリンク