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Risley, United Kingdom

Gibb F.G.F.,University of Sheffield | Travis K.P.,University of Sheffield | Hesketh K.W.,National Nuclear Laboratory
Mineralogical Magazine | Year: 2012

The heat outputs of higher burn up spent fuels (SF) create problems for disposal in mined repositories, including needs for reduced container loadings and extended pre-disposal cooling. An alternative that is less temperature sensitive is deep borehole disposal (DBD) which offers safety, cost, security and other potential benefits and could be implemented relatively quickly using currently available deep-drilling technology. We have modified our previously proposed version of DBD to be more appropriate for higher burn-up fuels by using smaller (0.36 m diameter) stainless steel containers, a smaller (0.56 m diameter) borehole, and different support matrices. We present the results of new heat-flow modelling for DBD of UO2 and MOX SF with burn ups of 55 and 65 GWd/t showing how temperatures evolve, especially on the outer surface of the containers. Consequences for the performance of the support matrices and the disposal concept are discussed. The thermal modelling indicates DBD is a viable option for higher burn-up SF and could be a practical disposal route for many combinations of fuel types, burn ups, ages and container loadings. Further, the results suggest that DBD of complete fuel assemblies, a desirable option, would be feasible and require much shorter pre-disposal cooling than necessary for disposal in mined repositories. © 2012 The Mineralogical Society. Source

Jackson S.F.,Lancaster University | Monk S.D.,Lancaster University | Lennox K.,National Nuclear Laboratory
Radiation Measurements | Year: 2013

We describe the optimisation of RadLine®; a small, real time, remotely operated radiation detector, which consists of an inorganic scintillation crystal coupled to a fibre optic cable transporting produced photons to a CCD camera some distance away. RadLine® is tested in a beta and gamma narrow radiation field of 2.4 GBq, from a Caesium-137 (662 KeV) source, at doses rates between 0.125 mSvhr-1 and 10 mSvhr -1. Our results establish that the lower limit of the device corresponds to a dose rate of 0.2 mSvhr-1, constrained by the signal to noise ratio of the instrument. We also demonstrate the process of characterising the RadLine® for utilisation underwater due to its partial electrical inactiveness; and to consider how the instrument might perform in aquatic environments and ultimately in a First Generation Magnox Storage Ponds (FGMSP). The RadLine® brings a marked difference to actual underwater radiation monitoring devices such as; HPGe, CZT and GM detectors, which not only incorporate the whole electronics within and are more bulky, only perform over a short range. The RadLine®'s design offers signification value for intermediate (>100 m) and long range detection. © 2013 The Authors. Published by Elsevier Ltd. All rights reserved. Source

Mills R.W.,National Nuclear Laboratory
Nuclear Data Sheets | Year: 2014

The effects of correlations between uncertainties of independent yields are considered to propose a method of including covariance terms within uncertainty propagation for spent fuel inventory calculations and a method outlined to achieve this. The use of the "Total Monte-Carlo" technique for such calculations are investigated for a simple decay example and for the case of a fission pulse calculation and the results discussed. © 2014. Source

Gupta J.,University of the Sciences in Philadelphia | Gupta J.,Bristol Myers Squibb | Nunes C.,Bristol Myers Squibb | Vyas S.,Accelrys | And 2 more authors.
Journal of Physical Chemistry B | Year: 2011

The objectives of this study were (i) to develop a computational model based on molecular dynamics technique to predict the miscibility of indomethacin in carriers (polyethylene oxide, glucose, and sucrose) and (ii) to experimentally verify the in silico predictions by characterizing the drug-carrier mixtures using thermoanalytical techniques. Molecular dynamics (MD) simulations were performed using the COMPASS force field, and the cohesive energy density and the solubility parameters were determined for the model compounds. The magnitude of difference in the solubility parameters of drug and carrier is indicative of their miscibility. The MD simulations predicted indomethacin to be miscible with polyethylene oxide and to be borderline miscible with sucrose and immiscible with glucose. The solubility parameter values obtained using the MD simulations values were in reasonable agreement with those calculated using group contribution methods. Differential scanning calorimetry showed melting point depression of polyethylene oxide with increasing levels of indomethacin accompanied by peak broadening, confirming miscibility. In contrast, thermal analysis of blends of indomethacin with sucrose and glucose verified general immiscibility. The findings demonstrate that molecular modeling is a powerful technique for determining the solubility parameters and predicting miscibility of pharmaceutical compounds. © 2011 American Chemical Society. Source

Maddrell E.,National Nuclear Laboratory
Chemical Engineering Research and Design | Year: 2013

Future nuclear fuel cycles will benefit from innovations in waste immobilisation technology allowing optimised waste management strategies to be deployed. Hot isostatic pressing (HIP) has the potential to be central to these novel immobilisation technologies because of its ability to consolidate a wide variety of wastes into durable wasteforms. HIP is currently being developed by the National Nuclear Laboratory for the immobilisation of plutonium containing wastes and residues, but its flexibility as a process makes it ideal for future fuel cycles. © 2012 The Institution of Chemical Engineers. Source

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