Weight on bit downhole MWD sensors can measure weight-on-bit more accurately and transmit the data to the surface. Weight on bit Weight on bit (WOB), as expressed in the oil industry, is the amount of downward force exerted on the drill bit and is normally measured in thousands of pounds. Weight on bit is provided by drill collars, which are thick-walled tubular pieces machined from solid bars of steel, usually plain carbon steel but sometimes of nonmagnetic nickel-copper alloy or other nonmagnetic premium alloys. Gravity acts on the large mass of the collars to provide the downward force needed for the bits to
Isotope separation nuclear weapons. Plutonium-based weapons use plutonium produced in a nuclear reactor, which must be operated in such a way as to produce plutonium already of suitable isotopic mix or "grade". While different chemical elements can be purified through chemical processes, isotopes of the same element have nearly identical chemical properties, which makes this type of separation impractical, except for separation of deuterium. There are three types of isotope separation techniques: The third type of separation is still experimental; practical separation techniques all depend in some way on the atomic mass. It is therefore generally easier to separate isotopes with a