Community Research and Development Information Service - CORDIS

FP6

Ultrasonic and Radiography Investigations of Defects in Ductile Cast Iron Casks for Disposal of Spent Nuclear Fuel

Funded under: FP6-JRC

Abstract

The Swedish concept for geological disposal of spent nuclear fuel (KBS-3) is based on copper over-pack and inner container of ductile cast iron (DCI) with twelve (BWR) and four (PWR) channels for fuel assemblies. The cast iron insert provides mechanical strength required for handling and integrity of the canister under hydrostatic stresses in deep underground repository. Assessment of the probability for canister failure requires detail understanding of the role of various technological defects in ductile cast iron and development of the methods for their non-destructive examination (NDE). Therefore, the aim of the current study was to characterize microstructure defects in several DCI inserts by various non-destructive and destructive techniques to determine advantages and limitations of each technique and to contribute to better understanding of the processes leading to canister failure.
The report contains four sections including: 1) microstructure characterization, 2) radiography, 3) ultrasonic examination and 4) crack growth analysis. Although material from three different ductile cast iron inserts was investigated (referred to as I24, I25 and I26), most if the work is devoted to I26 insert. DCI in this insert, despite its relatively homogeneous and isotropic microstructure, contains various defects, especially large slag inclusions and oxide filled cracks, blowholes and pinholes, scabs, surface roughness and others. Increased concentration of slag defects was found along the inner interfaces of the canister channels, where tensile stresses develop during hydrostatic compression. Film radiography of outer insert walls detected slag defects and cracks oriented parallel to the beam. With conventional radiography only 1/3 of the wall can be examined per one exposure due to large wall thickness variations and limited dynamic range of conventional film.

Additional information

Authors: LOFAJ F, European Commission, Joint Research Centre, Institute for Energy, Petten (NL);METTEN L, European Commission, Joint Research Centre, Institute for Energy, Petten (NL);VAN DE SANDE A, European Commission, Joint Research Centre, Institute for Energy, Petten (NL);SELDIS T, European Commission, Joint Research Centre, Institute for Energy, Petten (NL);NILSSON K F, European Commission, Joint Research Centre, Institute for Energy, Petten (NL);ERIKSSON A, European Commission, Joint Research Centre, Institute for Energy, Petten (NL)
Bibliographic Reference: EUR 22145 EN (2006), 77 pp. Free of charge
Availability: Available from European Commission, JRC Knowledge Management Unit, Ispra (IT) Tel: +39 033278 9893 Fax: +39 033278 5409 E-mail: jrc-info@ec.europa.eu or Bruxelles (BE) Tel: +32 2 295 76 24 Fax: +32 2 299 63 22
Record Number: 200718921 / Last updated on: 2007-03-16
Category: PUBLICATION
Original language: en
Available languages: en