Assessment of copper canisters for spent nuclear fuel requires means for detecting and sizing voids as small as 1 mm in diameter, located up to 4 mm under the surface. Eddy current technique for the detection and characterisation of deep voids in copper is presented in the paper. Results were obtained using two deep penetrating probes, the standard MDK 33 from Rohman, and a specially designed probe MDF 1201 from Leotest. The detection ability of the above probes was evaluated and compared using a specially designed sandwich specimen. The specimen was designed to simulate voids with different volumes, located in copper at different depths. Eddy current responses of the two probes were acquired using an automatic scanner for a number of artificial voids with different depths and volumes. The method of defect characterisation (estimating void depth and size) was established. It was shown that the detection of artificial void (cylinder with diameter 1mm and height 1 mm) located at the depth of 4 mm was possible using the probe MDF 1201 at the test frequency of approx. 700Hz. It appeared that defect characterisation was relatively simple task consisting of two steps, estimating the void depth based on the phase angle of its response, and using EC response amplitude for estimating the void diameter.
Deep penetrating eddy current for detecting voids in copper
Tief eindringender Wirbelstrom zum Nachweis von Hohlräumen in Kupfer
2002
9 Seiten, 10 Bilder, 1 Tabelle, 3 Quellen
(Nicht paginiert).
Conference paper
Storage medium
English
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