Patent Number: 
Section: abstract

An apparatus with which areas near surfaces in a water environment that are contaminated by radioisotopes are decontaminated by non-thermal laser peeling without suffering re-melting, re-diffusing and re-contaminating. The apparatus includes a piping structure with which a substance to be irradiated that has been deposited on outer and inner surfaces of a nuclear reactor pressure vessel, and a nuclear reactor container tank, and the internal nuclear reactor structures all having been contaminated with radioisotopes, can be removed in the water environment. The piping structure, to secure a region in a water environment that is gas pressurized to discharge the water and filled with the gas to not interfere with laser irradiation, has a semi-hermetically closed, incomplete water seal that is half-open with a siphon provided downward, a mechanical structure that withstands water pressure in a radial direction, and an extendable bellows-like tube to enable the piping structure to tilt.