In-situ laser cutting of secondary shutdown system SS321 pipeline for replacement of double check valve at KKNPP-1 reactor

In Kudankulam Nuclear Power Plant (KKNPP-1), there was specific and urgent requirement to replace double check valve (DCV-60) of 2nd stage emergency core coolant system (ECCS), by cutting of 16 mm thick SS321 pipe joints during its shutdown maintenance. This report provides details of development of laser cutting technology for the cutting of pipes connected to DCVs, using 250 W average power fiber coupled pulsed Nd:YAG laser. A miniature bending laser cutting nozzle and pipe mountable orbital laser cutting manipulator was specially developed and laser process parameters were optimized for cutting under challenging conditions of space restriction. By using this laser cutting technology, four pipe joints were successfully cut at KKNPP-1 reactor. (author)