This paper describes the main features of the Laser Megajoule (LMJ) an equivalent project in France to the NIF project in USA. It has been sized to achieve ignition of a small amount of DT and to produce fusion energy in a laboratory with a significant gain, by imploding small capsules filled with a DT mixture. The paper explains the main issues to design the target area because of the large emissions of neutrons, x-rays and debris due to the explosion of the target. We show that Phebus in France as well as Nova in USA can be used as test beds to study the threats expected on the first wall of the target chamber due to the large burst of neutrons, x-rays and shrapnels emitted from the exploding target.