Design and characteristics of the JRR-3M thermal neutron radiography facility and its imaging systems

The JRR-3M thermal neutron radiography facility was constructed in the JRR- 3M of the Japan Atomic Energy Research Institute in 1991 and has been used as a research facility for various kinds of research fields. The characteri stics of the facility have been briefly reported and declared to be excelle nt in neutron flux and in collimator ratio. Additionally, the authors have measured the beam flatness and the scattered components and have compared t hese measured characteristics with the design values. The neutron source, t he beam tube, and the radiography rooms are described in detail and their d ata are applied to the analyses of the characteristics. The description of the radiography rooms includes beam size definition tubes and beam shutters , which are the most important components in the room. Also described are t he restrictions on the size and shape of the sample, the background dose ra tes, and equipment information. The highperformance of the facility enables advanced imaging techniques such as high spatial resolution imaging and hi gh temporal resolution imaging. The high-resolution static neutron radiogra phy system using a cooled charge-coupled device camera has the capability t o take neutron radiography images with 72 mu m of spatial resolution. The h igh frame rate neutron radiography system has the capability to image high- speed phenomena with 4500 frames/s of temporal resolution. Both neutron rad iography systems are described in detail especially for key components such as fluorescent converters and cameras.