An intervertebral space distraction and implantable device assembly provides sequentially axially wider spacers that are to be sequentially inserted into and removed from an intervertebral space to widen the space until a desired anatomical spacing of the adjacent vertebral bones is restored. The rinse discharge nozzle is so moved on the substrate as to continuously supply pure water onto the substrate from a slit discharge port of the rinse discharge nozzle while sucking and recovering the pure water from the surface of the substrate through a slit suction port, and a series of development is performed in a stationary state of the substrate. A method is also proposed for the computation of a modular operation using the circuit for the computation of Y0. The invention can be used in production of metal such as magnesium, strontium, zinc, and beryllium by vacuum smelting reduction process.