The ANSWERS Seminar, 25th-27th May 2010

The 2010 ANSWERS Seminar was held at the Wessex Hotel in Bournemouth, a location near to the superb Dorset coast and in close proximity to the town centre.

Over one hundred delegates attended all or part of the three-day meeting, with the programme covering the shielding, reactor physics and criticality technical areas. Programme topics included ANSWERS code developments, code applications, related general interest issues and software demonstrations. In addition to the seminar itself, parallel meetings of the UK Shielding Forum, the UK Working Party on Criticality and the UK Nuclear Science Forum were hosted at the same venue.

Day 1

The 2010 ANSWERS Seminar started on Tuesday 25th May with Radiation Shielding. The host for the day was Pat Cowan, ANSWERS Applications Area Manager for Radiation Shielding. Pat introduced a variety of presentations on the recent developments in the ANSWERS Shielding codes and supporting tools and a number of applications using the ANSWERS codes.

The morning started with a presentation by Geoff Dobson (Serco) entitled "Gamma Source Modelling in MONK for use in MCBEND". He described some features that have been developed to allow the calculation of a gamma source in MONK for use in MCBEND. This was followed by a presentation by Ian Adsley (Nuvia) on work he has carried out on behalf of the DECC Global Threat Reduction Programme. This involved determining the concentration and profile of activation and fission product gamma-ray emitting radio-nuclides in a radioactive waste storage vault in Kazakhstan. This was followed by a short talk given by Kim Vignitchouk (Serco) on recent work to update the Activation and Fission product libraries used by MCBEND and RANKERN, following the discovery of an error on the JEF2.2 data. The session ended with a presentation on the Imperial College code Radiant, given by Paul Smith (Serco). Radiant is a deterministic code that has undergone a lot of recent developments.

Following the morning break, George Wright (Serco) gave a presentation on "Uncertainty Analysis". This talk was an updated version of previous talks on the same subject given in previous seminars. It covered all sources of uncertainty and how MCBEND can be used to evaluate some of the uncertainties. A worked example, the Iron Benchmark, was presented. This was followed by an interesting presentation given by Ian Terry (AREVA NP) entitled "Some field experience in using RANKERN for PWR dismantling". The geometry features of Unified Source in RANKERN had enabled Ian to model realistic shapes for some complex sources. David Picton (Serco) ended the morning session with a talk entitled "Random number generators and GRID processing in MCBEND". David talked about the Random Number generators in MCBEND and what they are used for. He went on to describe parallel calculations with MCBEND using GRID processing, where each processor uses a distinct random number sequence, while maintaining the reproducibility of results. He finished with some new features in MCBEND 11 that facilitate GRID calculations in a number of ways.

The afternoon session started with Adam Bird (Serco) giving an update on the current status of Visual Workshop version 1 and a demonstration of the latest features available in Visual Workshop version 2. Version 1 is due for release in June 2010 and will be provided to customers alongside VISAGE and VISTA-RAY until March 2011. The main focus of version 2 is improved handling of complete cases with input and output files and results display using a new 3D VTK wireframe view. The demonstration included results display for MCBEND fluxes and responses on a scoring mesh, contribution probabilities for RANKERN scatter bodies and the MONK birth store. This was followed by an applications presentation given jointly by Dennis Allen, Richard Steadman (Serco Quedgeley) and Simon Shaw (British Energy) entitled "MCBEND Support for Flux Stringer Deployment". Several MCBEND studies were described that have been undertaken prior to deployment of a neutron flux stringer at Hunterston B. These have assisted with the stringer design and the choice of deployment location. Next Peter Roocroft (BAE Systems) described some work he has been involved in using MCBEND to help with the Shield Design of a Neutron Generator. In the study calculations for dose-rates from neutrons and capture gammas were performed using MCBEND.

Following the afternoon break two presentations were given on the IGES Import method used to import Computer Aided Design (CAD) geometries into MCBEND and MONK. The first talk was given by Keith Searson (Sellafield Ltd) and described the OiNC CAD import and tracking system which has been developed as part of the NCD collaboration between Serco and Sellafield Ltd. OiNC allows users to use the full geometry functionality of solid CAD modellers, with no meshing approximations, and tracks directly through CAD models. The second talk was given by Adam Bird (Serco) and described the implementation of the IGES Import method into a development version of MCBEND10A. This covered connecting the IGES file to the MCBEND calculation, defining the IGES model location within the FG geometry, defining materials, visualisation of resulting geometry and initial testing. Testing has compared results for simple models from the IGES Import method to TETMESH HOLE and FG Methods. Finally, Pat Cowan ended the day by describing the current status and future plans for the ANSWERS Shielding Area.

Day 2

The second day of the seminar was devoted to Reactor Physics. The host for the day was Tim Newton, ANSWERS Technical Director and Applications Area Manager for Reactor Physics. Tim introduced a variety of presentations on the recent developments to the codes, nuclear data libraries and tools in the Reactor Physics area, and a number of applications using the ANSWERS Reactor Physics codes.

The morning started with a presentation by Tim Ware (University of Birmingham) entitled "Measurement and Analysis of The resolved Cross Sections of The Natural Hafnium Isotopes". The study formed part of Tim's Phd project which was performed in collaboration with GEEL University (Belgium) and Serco. Tim described new measurements and evaluation of the hafnium isotopes. This was followed by two talks on calculation of nuclide inventories using WIMS. The first of these was by Pavel Mikoláš (Škoda) who described calculations for fuel from the Russian VVER-1000 reactors Kalinin and Balocovo. The second talk was a joint presentation by Jimmy Sudana (Tractebel Engineering) and Glynn Hosking (Serco) on the isotopic analysis of UOX and MOX fuel for PWR within the ARIANE project. It was found that improved results were obtained by representing the environment of the MOX by using a series of supercells.

Following the morning break, Paul Bryce (British Energy) gave a talk on the status of the PANTHER code. Of particular interest was the development of a microscopic depletion facility which improves the modelling capability for historic effects. This was followed by a talk by Dave Powney (Serco) entitled "Zebra Core 8 Analyses". The talk illustrated how the use of the ECCO module extends the applicability of WIMS to fast systems. Next Tim Newton gave a presentation of the XT method in WIMS. XT allows cross sections to be scored in MONK and transferred to the WIMS interface. This was followed by a talk on the CACTUS characteristics method by Glynn Hosking (Serco). The salient points were techniques for accelerating the solution and additional current edits. Nigel Davies (Serco) ended the morning session with a talk on the new SPH homogenisation treatment in WIMS. SPH is a method of homogenisation which preserves reaction rates in the homogenised region.

The afternoon session started with a presentation on the Imperial College code RADIANT given by Paul Smith (Serco). RADIANT is a finite element transport code which can solve the neutron transport equations by a number of methods. This was followed by a talk by Martin Knight (British Energy) entitled "A Prototype WIMS/PANTHER Route for PWR MOX Core Analysis". The presentation described the development of methods to model MOX fuel assemblies in PWR and included results of validation against the KAIST international benchmark. Next Glynn Hosking (Serco) gave an update on functionality which has been added to WIMSBUILDER for the treatment of MOX fuel supporting result presented in the previous presentation.

Following the afternoon break, Tim Newton gave a talk on the status of MAX. MAX solves the neutron transport equation by Monte Carlo perturbation theory. Recent developments have enabled excellent results to be obtained for homogeneous problems and fuel perturbations. More study is required for perturbations in low density regions or in heavy absorbers. This was followed by Christopher Dean (Serco) who gave a talk entitled "MONK Doppler Broadening on the fly". The presentation described a method for calculating cross sections in BINGO libraries as a function of temperature at run time, thus removing the restriction of discrete temperatures in BINGO input libraries. Excellent results were obtained when the technique was validated against the KRITZ series of experiments which include room and elevated temperature situations.

Finally Tim Newton closed the proceedings by reviewing the current status and plans for the reactor physics area. WIMS 10 has been released as a beta version containing the following enhancements: new input/output features; CACTUS3D; ECCO; temperature calculation; material dependent fission spectra; resonance shielding for materials at different temperatures; perturbation methods; fixed source module; and, whole core PBMR methods.

Day 3

The Criticality day began with an introduction to the day by the ANSWERS Manager Paul Smith and a short introcution by Malcolm Armishaw, ANSWERS Applications Area Manager for Criticality. This was followed by a talk by Anthony Wilson (Sellafield Ltd) on MOX powders and pellets, their sensitivity to moderation, and how care is needed when dealing with such systems. This was followed by a presentation by Jackie Martin (British Energy) on the MONK modelling of AGR storage tubes using MONK, and the various failure modes if a fuel stringer drops. The next talk was by Keith Searson (Sellafield Ltd) on the progress being made with the CAD development task, the range of supported CAD formats and several acceleration techniques for speeding up the tracking. The final talk of the first session was by Derek Putley (Serco) who described several techniques for reducing the standard deviation on results, including the formula for combining multiple MONK runs, and smoothing algorithms for results from MONK calculations with a varying parameter.

The first talk of the second session was by Christopher Dean (Serco) who gave an update on the BINGO collision processor, the run time Doppler broadening progress and testing, the Dagan scattering kernel technique, and the status of the libraries available with, and in preparation for, MONK. The next talk was by Mary Erlund (National Nuclear Laboratory) on their GEMSTONE cluster, and their use of the cluster to compare a series of simple benchmarks using DICE and BINGO with MONK. The final presentation of the morning was by Tim Fry (Serco) on the impending release of Visual Workshop 1 and the results display features that are being developed for Visual Workshop 2, including a demonstration of some of those features such as display of birth store data in a MONK case using an HDF5 format file.

The first talk of the afternoon was by Andrew Sutton (Sellafield Ltd) on Best Practice on MONK use, this included describing the level of detail supplied via comments in input decks to make QA checking and future changes easier. He also covered their SMFL tool to simplify the preparation of material compositions. The next talk was by Simon Richards (Serco) on the parallelisation of MONK, this included an overview of parallelisation options, what was implemented in MONK and how, the MONK scoring options, and some initial test results. The final talk of this session was by Richard Neal (Sellafield Ltd) on the progress being made with the Run-Time Doppler Broadening in MONK, including an overview of why we need it and how it has been implemented, details of the performance available.

The first talk of the final session was by James Dyrda (AWE) who gave an update on the progress of the benchmark evaluation of UK IEU experiments for contribution to the ICSBEP. This included an overview of the experiment, how few of the original team are now available to discuss the experiment, and that some of the data is found literally in the 'attic'. James described the future work to be done, and concluded by comparing the costs of archiving the experimental data we have with the cost of repeating the experiments themselves (if we could). The next talk was by Paul Smith (Serco) on the RADIANT code and how various techniques such as different angular basis functions, and sub-grid scale finite elements can provide greater efficiency and accuracy. The following talk by Nigel Davies (Serco) on coupling MONK to a thermal hydraulics code to provide temperature feedback for MONK burnup calculations. He described the new meshing technique for both burnup and thermal hydraulics meshing to enable the optimum mesh to be used with each feature. The final talk of the final session of the final day of the 2010 ANSWERS Seminar was by Malcolm Armishaw (Serco) and gave an update on the MONK status, the status of the libraries available and in preparation for MONK, and an overview of the main development tasks for the MONK code.

Malcolm concluded the session, the day, and the seminar, by thanking all the presenters for providing such a wide range of excellent presentations for the Criticality day. He thanked all the attendees for their support, hoped they had enjoyed this year’s seminar and wished them a safe journey home.


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