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Characterising the Mechanical Loads Acting on Nuclear Packages during Rail Transportation

Cummings, AD (2016) Characterising the Mechanical Loads Acting on Nuclear Packages during Rail Transportation. Doctoral thesis, Liverpool John Moores University.

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Abstract

The safe transportation of new and spent nuclear fuel is an essential part of the nuclear fuel cycle. The aim of this thesis was to obtain a more thorough understanding of the mechanical loading acting on heavy nuclear packages during rail transportation. There were two motivating factors for this study. Firstly, the design of equipment used to tie down a package to its conveyance has become more challenging with the recent trend of increasing package mass; often exceeding 100 tonnes. This difficulty is due to the advisory acceleration factors recommended for design. Despite widespread acceptance that the factors ensure safety, it is also recognised that for heavier packages they can be prohibitive and result in over engineered tie down systems. Secondly, transportation imparts complex dynamic mechanical loading on packages and the fuel assemblies within them. There have been no reported instances in the UK of problems caused by fuel vibrations. However international studies have prompted this investigation. A rail wagon and tie down system for a 100 tonne package were instrumented with accelerometers and strain gauges. The measurements were taken during a routine rail journey from Barrow-in-Furness to Sellafield. Continuous data was digitally recorded with a sampling rate sufficient to capture shock and vibrations up to 100 Hz. Accelerometers were selected to measure very low frequencies to capture quasi-static loading. Investigation of the frequency content of the accelerations indicated that digital filtering of the data is necessary to determine the magnitudes of the structural loading on tie downs. A method for designing a suitable filter has been developed. A sensitivity analysis of different filters indicated there is a possibility for over estimating loads based on measured data due to poor filter design. Industrial design of tie downs using FEA requires pragmatic run times. This motivated a comparison of the measured strain time histories with the results of a linear static FEA model. The correlation between measured and predicted strains, was strong at frequencies < 3.5 Hz. A residuals analysis indicated that the model predicted the underlying strain process accurately. The methods described are generic and adaptable. They will aid any future experimental work, to characterise shock, vibration and quasi-static loads acting on nuclear packages and their ancillary equipment.

Item Type: Thesis (Doctoral)
Uncontrolled Keywords: Rail; Nuclear Packaging; Accelerations; Strain; Signals Processing; Finite Element Analysis
Subjects: T Technology > TF Railroad engineering and operation
T Technology > TK Electrical engineering. Electronics. Nuclear engineering
Divisions: Maritime and Mechanical Engineering
Date Deposited: 17 Nov 2016 10:25
Last Modified: 17 Nov 2016 11:50
Supervisors: Rothwell, G and Matthews, C
URI: http://researchonline.ljmu.ac.uk/id/eprint/4666

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