Beryllium is a naturally occurring, silver-grey metal. Lighter than aluminum and more rigid than steel, Be has many unusual properties which make it ideal for several applications, including aircraft and space vehicle structure, x-ray machine assemblage, mirrors, ceramics, metal alloys, and, since the 1950's, nuclear technology including weapons and reactors.
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An initiator is a device that produces a timed burst of neutrons to initiate a fission chain reaction in a nuclear weapon. Initiators made of polonium-210 and beryllium were located at the center of the fissile cores of early atomic weapons. The highly radioactive isotope of Polonium (Po-210) is a strong alpha emitter. Beryllium will absorb alphas and emit neutrons. This isotope of polonium has a half life of almost 140 days, and a neutron initiator using this material needs to have the polonium, which is generated in a nuclear reactor, to be replaced frequently. To supply the initiation pulse of neutrons at the right time, the polonium and the beryllium need to be kept apart until the appropriate moment and then thoroughly and rapidly mixed by the implosion of the weapon.
Beryllium is used as the reflector material (or 'pit liner') in most contemporary American nuclear weapons and thermonuclear primaries. The 'primary', or weapon trigger, consists of three components: the central spherical plutonium 'pit' or core, the Be 'pit liner', and a surrounding high-explosives shaped-charge. The pit liner, sometimes also referred to as the "skull", surrounds the spherical plutonium pit and is in turn surrounded by high explosives. All three of these components together make up a modern nuclear weapon's "primary", or trigger, which initiates the thermonuclear reaction in a weapon's secondary components. The beryllium liner effectively acts as 1) a reflector which directs neutrons back into the plutonium pit; 2) a tamper which initially contains and thereby helps to increase the force of the explosion; and 3) a generator of additional neutrons.2 A flux of neutrons at the beginning of a nuclear weapon's detonation initiates critical mass, which subsequently leads to the weapon's designed destructive yield.
The Department of Energy uses beryllium metal to fabricate weapons components and to facilitate a number of weapons-related experiments. Based on its analysis of the President's 2001 Nuclear Posture Review, the National Nuclear Security Administration (NNSA) estimated that it would need approximately 90 tons of beryllium metal to meet mission requirements over the next 30 years. About 50 tons of the material is currently available for purchase from the Defense Department's National Defense Stockpile. Because the only domestic producer of beryllium metal from ore ceased production in 2000, NNSA had been uncertai how it would overcome the perceived shortfall.
NNSA's existing beryllium metal weapon component manufacturing process involves machining down large blocks of beryllium metal so that only about four percent of the feed material ends up in the final product. This means that the process results in a discard of 96 percent of the material as scrap. Technical experts explained that this metal could not be reused for weapons production without reprocessing since it contains impurities from the manufacturing process. Near-net shaping, on the other hand, is a process by which beryllium powder is sized to a shape closer to that of the final parts, thereby allowing NNSA to use significantly less beryllium metal to manufacture the same parts.
Beryllium Is a Silver-Gray Metallic Element That Occurs Naturally in About 30 Minerals. Beryllium was discovered in 1798, but it was not widely used in industry until the 1940s and 1950s