PIE of pressure tubes and other core components periodically removed from the reactors is very important for lifetime management of coolant channels of Indian PHWRs. A large lead cell has been set up in BARC for carrying out PIE of full-length pressure tubes and other irradiated components from Indian PHWRs. The basic examinations done on a pressure tube include visual examination, measurement of diameter and sag profiles, hydrogen content and oxide layer thickness, tensile properties and fracture toughness. Other examinations include metallography, eddy current and ultrasonic tests, micro-structural evaluation and neutron radiography. The PIE facilities also include advanced NDT instruments for monitoring oxide layer and hydride blisters, facilities for hydrogen estimation of scrape or trepanned samples from pressure tubes and a computerised remote cutting, milling and drilling machine for preparation of specimens for fracture toughness evaluation.

Hydrogen content is measured using either bulk samples or scrape samples. The bulk samples are removed from different axial locations of pressure tube removed from reactor and hydrogen content is measured by inert gas fusion (IGF), differential scanning calorimetry (DSC) and hot vacuum extraction quadruple mass spectrometry (HVEQMS) techniques. Scrape samples are removed using the sliver-sampling tool and hydrogen content is measured using DSC or HVEQMS techniques. As on today, hydrogen measurement has been carried out on more than 100 bulk samples and more than 300 scrape samples.

The ductile-brittle transition temperature has been estimated for a number of irradiated pressure tubes having different levels of hydrogen concentration. The tests have been carried out on rings cut from the pressure tubes and doing tensile tests at different temperatures to determine the fracture strain. Fracture toughness is estimated using an empirical correlation.

The results of PIE are used for deriving the necessary inputs for refining the models of the degradation mechanisms. Feedback taken from the results generated out of the [H/D] concentration measured have resulted in taking several safety related decisions related to the health of the coolant channels and helped in understanding the hydrogen pickup behaviour and validation of the computer codes against data relevant for Indian PT material.

In addition to the pressure tube, other core components like calandria tube and garter spring spacers have also been examined. So far, twenty-three garter spring spacers have been