Tome Architecture and management of a geological repository - Andra

7 - Spent fuel repository zoneSKB’s studies on the manufacture of copper envelopes included reliability testing of NDT systems andprocedures on over twenty welded lids using radiographic and ultrasonic inspection, and on over onehundred test samples exclusively by radiography.It should also be mentioned that an electromagnetic inspection system is currently in development.• Digital Radiography (DR) testingThe main aim of this radiography system is to inspect any volumetric defaults presented by the lidweld.The system designed by SKB enables 1-mm pores to be detected in a weld carried out over the wholecircumference of a canister (Figure 7.3.6).Figure 7.3.6Radiographic equipment for testing the electron beam weld of the coppercanister lidThe major advantage of the radiographic process is that it provides a full image of the weld withprecise default identification, both in volume and position (on the circumference).However, destructive testing carried out subsequently and randomly on the X-rayed welds has shown thatthis identification was sensitive to canister centring and ovalisation.Furthermore this method presents the following limitations:- positioning the discontinuities in the radial direction is delicate (in the weld thickness);- small discontinuities are hard to detect in the axial direction of the canister.Dossier 2005 granite - ARCHITECTURE AND MANAGEMENT OF A GEOLOGICAL REPOSITORY208/228