Method of laser welding a nuclear fuel rod

摘要

A method of welding a fuel rod includes the following steps. An end plug and a cladding tube of the fuel rod are brought together to abut each other, and welded by applying a laser beam directed to a welding zone to melt material of the end plug and the cladding tube. The welding is sensed by sensing radiation within a first wavelength range, which includes the wavelength of the laser beam coming from reflections from the welding zone, sensing radiation within a second wavelength range different from the first wavelength range, which includes infrared radiation from melted material, and sensing radiation within a third wavelength range different from the first and second wavelength ranges, which includes radiation from plasma. The welding and melting of material is monitored by monitoring the sensed radiations.

主权项

1. Method of welding a nuclear fuel rod including two end plugs, a cladding tube and a pile of fuel pellets in the interior of the cladding tube, the method comprising the steps of:
bringing one of the end plugs and the cladding tube together to abut each other at an interface; and welding the end plug and the cladding tube by means of a welding equipment by applying a laser beam of a laser source of the welding equipment, the laser beam having a wavelength and being directed along an optical path of the welding equipment to a welding zone at the interface to melt material of the end plug and the cladding tube at the interface; wherein the welding takes place in a closed enclosure containing an atmosphere of helium at a pressure above the atmospheric pressure, wherein the closed enclosure encloses the end plug and end section of the cladding tube, and wherein the method comprises the steps of: evacuating the interior of the cladding tube and the closed enclosure to a certain vacuum level during a predetermined time period, then filling the closed enclosure and the interior of the cladding tube with helium to a predetermined pressure, pre-positioning the end plug on the cladding tube at a determined distance from the cladding tube before the evacuating step, thereby permitting a free flow of gas from and to the interior of the cladding tube, and final positioning of the end plug on the cladding tube after the filling step and before the welding step, and wherein the method comprises the further steps of: sensing the welding by sensing radiation from the welding zone comprising:
sensing radiation within a first wavelength range, which includes the wavelength of the laser beam coming from reflections from the welding zone;sensing radiation within a second wavelength range different from the first wavelength range, which includes infrared radiation from melted material in the welding zone;sensing radiation within a third wavelength range different from the first wavelength range and the second wavelength range, which includes radiation from plasma in the welding zone; and monitoring the welding and melting of material by monitoring the sensed radiations.