Calandria and neutron shield unit for nuclear reactors

A construction is described that provides a calandria vessel and neutron shield tank in a single unit. The combined unit can be fabricated in sections and can be readily assembled on site, thereby avoiding transportation difficulties. The unit also avoids the need for accurately positioning a conventional calandria vessel relative to neutron shield tanks so that the calandria tubes are in perfect alignment with the corresponding tubes through upper and lower shield tanks. It is preferred that the calandria tubes be sealed into the aligned passages of the opposed neutron shield tank by welding, but detachable joints, such as glanded joints, may be employed. (U.K.)