The thick steel vessels must withstand the high temperature and pressure of the reactor core which is enclosed in thick concrete walls so that gamma rays and neutrons cannot escape. In an emergency, the system shuts down and fission stops completely. The fuel rods must be handled remotely by robots.The spent fuel rods are removed by remote control and stored for up to a year in cooling ponds. Unused uranium and plutonium are removed and then they are stored in sealed containers in deep trenches for further use. The fission products and steel cans can be stored in underground caverns, possibly as glass blocks. Intermediate level waste is stored in drums in concrete buildings and low-level waste in sealed containers dumped in trenches.