Long-lived fission product processing method using neutrons

A long-lived fission product processing method using neutrons comprising:

• introducing neutron-containing primary particles into an FFAG accelerator including a plurality of sector magnets and at least one radio frequency accelerating device arranged in a ring shape;
• accelerating the primary particles to high energy while circulating the primary particles inside the FFAG accelerator through magnetic field and electric field effects under conditions in which, in the FFAG accelerator, the frequency of a radio frequency electric field is fixed while setting a magnetic field gradient coefficient k in accordance with equation (1), shown below,
• k
• ≈
• T
• M
• 
• (
• T
• M
• +
• 2
• )
• (
• 1
• )
• where T is kinetic energy of the primary particles at a stage at which the primary particles form a stored beam and M is rest mass energy of the primary particles;
• letting the primary particles that have been accelerated collide with a plate-shaped target located inside the FFAG accelerator to generate first neutrons of high energy through break-up of the primary particles and second neutrons of low energy through excitation of atomic nuclei in the plate-shaped target;
• and
• performing nuclear transmutation of a first long-lived fission product through collisions of the first neutrons with the first long-lived fission product, the first neutrons forming a beam in an extension direction of an incident path of the primary particles to the plate-shaped target, and the first long-lived fission product being located in a direction of travel of the beam, and
• performing nuclear transmutation of a second long-lived fission product located in proximity to the plate-shaped target through the second neutrons spreading out around the plate-shaped target.