Arbalest not be the same as an arbalest). In some cases, the word has been used to refer to arbalists, the people who actually used the weapon. Arbalest The arbalest (also arblast) was a late variation of the crossbow coming into use in Europe during the 12th century. A large weapon, the arbalest had a steel prod ("bow"). Since the arbalest was much larger than earlier crossbows, and because of the greater tensile strength of steel, it had a greater force. However, the greater draw weight was offset by the smaller powerstroke, which limited its potential in fully transferring the energy
Pit (nuclear weapon) risk of predetonation and fizzle. Weapon-grade plutonium therefore has plutonium-240 content limited to less than 7%. Supergrade plutonium has less than 4% of the 240 isotope, and is used in systems where the radioactivity is a concern, e.g. in the US Navy weapons which have to share confined spaces on ships and submarines with the crews. Plutonium-241, commonly comprising about 0.5% of weapon-grade plutonium, decays to americium-241, which is a powerful gamma radiation emitter. After several years, americium builds up in the plutonium metal, leading to increased gamma activity that poses occupational hazard for workers. Americium should therefore be separated,