TY - RPRT A1 - Pavlovic, Mato A1 - Takahashi, K. A1 - Müller, Christina A1 - Boehm, Rainer A1 - Ronneteg, U. T1 - NDT Reliability - Final report - Reliability in non-destructive testing (NDT) of the canister components N2 - This report describes the methodology of the reliability investigation performed on the ultrasonic phased array NDT system, developed by SKB in collaboration with Posiva, for inspection of the canisters for permanent storage of nuclear spent fuel. The canister is composed of a cast iron insert surrounded by a copper shell. The shell is composed of the tube and the lid/base which are welded to the tube after the fuel has been place, in the tube. The manufacturing process of the canister parts and the welding process are described. Possible defects, which might arise in the canister components during the manufacturing or in the weld during the welding, are indentified. The number of real defects in manufactured components have been limited. Therefore the reliability of the NDT system has been determined using a number of test objects with artifical defects. The reliability analysis is based on the signal response analysis. The conventional signal response analysis is adopted and further developed before applied on the modern ultrasonic phased-array NDT system. The concept of multi-parameter a, where the response of the NDT system is dependent on more than just one parameter, is introduced. The weakness of use of the peak signal response in the analysis is demonstrated and integration of the amplitudes in the C-scan is proposed as an alternative. The calculation of the volume POD, when the part is inspected with more configurations, is also presented. The reliability analysis is supported by the ultrasonic simulation based on the point source synthesis method. KW - POD KW - Reliability KW - Nuclear waste KW - Final disposal PY - 2008 UR - http://www.skb.se/upload/publications/pdf/R-08-129webb.pdf SN - 1402-3091 SP - 1 EP - 56 CY - Stockholm AN - OPUS4-20620 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Takahashi, Kazunori A1 - Pavlovic, Mato A1 - Bertovic, Marija A1 - Ewert, Uwe A1 - Müller, Christina A1 - Ronneteg, U. ED - Thompson, D.O. ED - Chimenti, D.E. T1 - Application of POD to complex industrial problems: new approaches N2 - Ultrasonic phased array NDE has been applied to ensure the integrity of canisters for encapsulation of spent nuclear fuel. The performance of the NDE system is evaluated by the POD analysis. The POD analysis using a common method, â versus a, has been modified for the phased array ultrasonic inspections by two approaches: to take more influencing parameters into a, and to use a more sophisticated quantity as â. The POD with new a allows more detailed interpretation of POD for each parameter, and the new â gives more realistic POD. The methods are discussed and demonstrated with experimental data. In addition, an investigation of human factors is being planned and the plan is discussed. KW - Nondestructive testing KW - Probability KW - Ultrasonics KW - Ultrasonic KW - Phased array KW - Probability of Detection (POD) KW - Reliability KW - Nuclear waste PY - 2009 SN - 978-0-7354-0629-2 U6 - https://doi.org/10.1063/1.3114180 N1 - Serientitel: AIP conference proceedings – Series title: AIP conference proceedings VL - 28 SP - 1824 EP - 1831 AN - OPUS4-26086 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bertovic, Marija A1 - Müller, Christina A1 - Fahlbruch, B. A1 - Pitkänen, J. A1 - Ronneteg, U. T1 - Human factors approach to the reliability of NDT in nuclear waste management in Sweden and Finland N2 - Nuclear power industry has the responsibility to manage and dispose of all radioactive waste from its plants. Finnish Posiva and Swedish SKB are leading in the world in the development of disposal of spent nuclear fuel. Their method consists of encapsulating spent nuclear fuel in copper canisters and depositing them in the bedrock at a depth of about 500 meters for the next 100 000 years, leaving the radioactivity to decrease naturally through the decay of the radioisotopes in it. The copper canisters, consisting of a copper tube, a lid and a bottom (which make the outer shell) and an insert made of a cast iron, need to be inspected for their structural integrity to ensure no critical defects are present in the materials and welds that could lead to a leakage of the waste into the environment. Data acquired by 4 different non-destructive testing (NDT) methods (i.e. UT, ET, RT and VT with a remote camera) are evaluated by skilled human operators and therefore could be subject to human error. Human Factors approach lies in identifying potential errors made by the human, their causes and ways of preventing them. A customized Failure Modes and Effects Analysis (FMEA) was conducted to anticipate possible human failures during the data evaluation. The results led to designing several experiments (e.g. diffusion of responsibility within the 4-eye principle, over trust in automated systems) which are being experimentally tested in ongoing projects. The results are expected to lead to the optimization of the procedures followed by the NDT operators and consequently to the improvement of the overall NDT reliability. T2 - 8th International conference on NDE in relation to structural integrity for nuclear and pressurised components CY - Berlin, Germany DA - 2010-09-29 KW - Human factors KW - Reliability KW - NDT KW - Nuclear waste PY - 2010 UR - http://www.ndt.net/article/jrc-nde2010/papers/32.pdf SN - 978-3-940283-30-6 IS - DGZfP-BB 125 (Th.3.A.2) SP - 1 EP - 10 CY - Berlin AN - OPUS4-23925 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -