A study of a conceptual design for a “cassette” compact toroid reactor, which emphasizes quick replacement, has been carried out. The quick replacement, accomplished by using a functional material, the SMA joint, is necessary to release the first wall from high neutron loading. The SMA joint permits the connection or disconnection of the joint part by means of a simple operation involving the control of the SMA temperature, without the need for an extremely intelligent robot. Pheripheral structural mechanisms have also been devised for the blanket and the shielding construction.