The ANSWERS Seminar, 24th-26th May 2016

The 2016 ANSWERS Seminar was held once again at the Haven Hotel in Sandbanks, Poole, over the period 24th to 26th May. It was attended by over 100 delegates from across the UK, Europe and China.

The three day event covered Shielding, Reactor Physics, and Criticality, with a technical programme which included presentations from both ANSWERS staff and customers.

Day 1: Radiation Shielding

The 2016 ANSWERS Seminar started on Tuesday 24th May with the Radiation Shielding day. Adam Bird introduced the day’s programme, which was split into four sessions.

The first session was hosted by Adam Bird and began with a presentation entitled 'Optimised Criticality Excursion Dose Contour Calculations', given by Jennifer Pryde (Amec Foster Wheeler). This was an interesting presentation describing MCBEND dose calculations for criticality events and noting that the minimum critical mass event may not be the bounding case for dose uptake. The second presentation; 'Radiological Waste Packaging Optimisation of Irradiated Control Rods using RANKERN', was given by Lars Ackermann (AREVA GmbH). This was an excellent presentation describing a large piece of work that could not have been completed in the required timescale without the speed of RANKERN. The final presentation of the first session was 'OpenMP Developments in MCBEND', presented by Adam Bird and Pietro Santagati (Amec Foster Wheeler). This presentation was delivered in two halves with Adam Bird providing an overview and Pietro Santagati providing more depth for those interested in the technical details.

The second session was chaired by George Wright. Adam Bird gave the first presentation; 'Release of RANKERN16A and New Features', which gave an overview of the new features of RANKERN16A. The second presentation 'Unified Tally Enhancements' was presented by Geoff Dobson (Amec Foster Wheeler). This presentation gave an overview of Unified Tally introduced in MCBEND11A, listing the scoring features currently being added and a development priority for the rest. The next presentation was 'Derivation of Ex-Core Detector Response Functions for Sizewell B' from Christophe Murphy (Amec Foster Wheeler), and described an application of MCBEND that utilised adjoint calculations. The last presentation of this session 'ICRP 116 Dose Response Functions' was given by George Wright. It described the differences between these dose conversion factors and the previous ones from ICRP103 and ICRP74.

The third session was chaired by Christophe Murphy. The first presentation 'Quantifying the Nuclear Data Uncertainty in Shielding Calculations with sampled BINGO libraries' from Tim Ware (Amec Foster Wheeler), talked about a set of BINGO libraries that have been produced to aid the analysis of the effect of uncertainties in the nuclear data on shielding calculations. The second presentation 'Uncertainty Quantification' by Max Shepherd (Amec Foster Wheeler) continued this theme. This presentation described a new tool 'Spruce' in Visual Workshop, which is used to aid uncertainty calculations. The next presentation 'Example Application: Creating Surface Source Description from UT Scoring', presented by Geoff Dobson (Amec Foster Wheeler), described how to use surface Unified Tally results as a Unified Source term in MCBEND. The final presentation of this session, 'Visual Workshop Update' by Tim Fry (Amec Foster Wheeler), talked about the current versions, error reports and current and future development work of Visual Workshop.

The fourth and final session was chaired by Geoff Dobson, starting with a presentation entitled 'Scalable Adaptive Deterministic Solvers Applied to Shielding Problems' by Steven Dargaville (Imperial College). This presentation talked about developments to FETCH2 and covered support for parallel computing. The final presentation of the day 'Status and Future Plans' was given by Adam Bird, and covered the current status of the ANSWERS shielding codes, the current error reports, and future plans, along with a reminder of the hotline service.

Day 2 : Reactor Physics

The Reactor Physics day of the 2016 ANSWERS Seminar was on Wednesday 25th May. The day was split into four sessions.

The first session began with a presentation by John Lillington (Amec Foster Wheeler). John discussed progress towards new build in the UK, including candidate designs for PWR, ABWR and SMR plant. Kenneth Lessnoff (EDF Energy) gave the next presentation, which described modelling of AGR reflectors with WIMS and PANTHER. The work aimed to get a better understanding of Channel Power Discrepancies (CPDs) between thermal and neutronic calculations. The following presentation was given by David Hughes (EDF Energy). David discussed further analysis of CPDs for AGRs, although in the context of end-of-life values. He concluded that using nuclear data libraries generated by WIMS improved accuracy in end-of-life CPDs, relative to when using ARGOSY-generated nuclear data libraries. The final talk of the session was given by Ben Lindley (Amec Foster Wheeler). Ben described recent developments of the WIMS/PANTHER route for BWRs. The components of the physics capability have been tested using a series of computational benchmarks, where it has been found that WIMS is functionally equivalent to established lattice codes for BWRs.

Session two began with a presentation by Nicolas Slosse (Tractebel). Nicolas discussed WIMS validation for PIE measurements of a gadolinium-loaded PWR assembly, where WIMS results were found to be in good agreement with measurements, and also with results from the SCALE code. Next, Pavel Mikolas (SKODA) described the effects of using different WIMS10 libraries on irradiated isotopics in VVER-1000 systems. David Powney (Amec Foster Wheeler) gave the next presentation, which detailed analysis of JEFF3 vs. JEF2.2 reactivity differences for water reactor lattices. The final presentation of the session was given by Glynn Hosking (Amec Foster Wheeler). Glynn described the implementation and testing of a new treatment of P1 scatter in CACTUS, and the impact of P1 scatter on calculations for typical UOX and MOX PWR pincells was discussed.

The first afternoon session began with another presentation from Ben Lindley, on use of the SPRUCE tool in Visual Workshop. SPRUCE can be used to perform uncertainty assessments for WIMS calculations. The following talk was given by Ray Perry (Amec Foster Wheeler). Ray described the used of sampled libraries in order to assess total uncertainties due to nuclear data. Copies of the sampled WIMS and BINGO libraries will be available for evaluation from summer 2016. Next, George Alford (Amec Foster Wheeler) presented analysis of the UAM benchmark. This work was concerned with uncertainty estimation for BWR systems. Uncertainties calculated with WIMS were found to be in close agreement with those calculated by other benchmark participants. The last presentation of the session was given by Brendan Tollit (Amec Foster Wheeler). Brendan discussed recent and planned developments of the new SP3 and SUBCHANNEL modules in WIMS.

The final session of the day began with a presentation by Peter Smith (Amec Foster Wheeler). Peter described WIMS and MONK calculations of a whole-core Sodium Fast Reactor benchmark. It was found that the WIMS and MONK results were generally in excellent agreement with results reported by other benchmark participants. The second talk of the session was given by Jim Gulliford (NEA). Jim described the new NEST framework, which will be used to help pass practical knowledge from experienced nuclear professionals to students and young professionals. The final talk of the day was from Glynn Hosking, and covered the current status of WIMS and potential future developments.

Day 3 : Criticality

The criticality day began with Simon Richards (MONK Design Authority, Amec Foster Wheeler) describing the current status of MONK, plans for the next release (MONK10B) and future developments. This was followed by a very interesting presentation by Zhou Qi (China Institute of Atomic Energy) on their experience of using MONK as their primary criticality code. Nigel Davies (Amec Foster Wheeler) then described progress on the search for an automated source convergence method for Monte Carlo codes. This work indicated that the fission matrix is useful, and Simon Richards then went on to describe the implementation of a fission matrix capability in MONK.

Simon Richards began the second session, describing a new energy-dependent scattering kernel in MONK using the Doppler broadening rejection correction method. Derek Putley (EDF Energy) presented results from the OECD/NEA WPNCS EGUNF benchmark on the reflector effect of SiO2 on used fuel, showing MONK performing well against other codes. He noted that changing the nuclear data leads to small but significant differences in results and that older nuclear data may overpredict capture in 28Si. Max Shepherd (Amec Foster Wheeler) introduced the new sensitivity-based similarity index for MONK validation cases. Ahmed Aslam (Amec Foster Wheeler) presented work on the effect of particle size on reactivity, demonstrating that a 'heterogeneous' reactivity peak exists for MOX, Uranium only and Plutonium only systems. Finally Adam Bird (Amec Foster Wheeler) discussed the new features in Visual Workshop 3C, including tools for uncertainty analysis, support for FG body reflection, the display of EROD bodies and the display of fission matrix eigenvectors.

Tim Ware (Amec Foster Wheeler) began the third session with a presentation on the creation of sampled WIMS and BINGO nuclear data libraries for use in uncertainty quantification. Max Shepherd then gave an interesting presentation on the use of Maximum Likelihood Estimators for robust estimation of bias and selection of validation experiments. Finally, Jim Gulliford updated us on the activities in the NEA and its ongoing work. Of particular interest is the NEA Education Skills & Technology (NEST) framework which aims to establish a multinational framework to maintain and build skills capabilities for the nuclear industry. The programme also aims to establish links between universities, research institutes and industry. This is of particular importance due to the growing trend to move from experiments to computer models and the increased use of multidisciplinary areas of nuclear engineering (such as the increased focus on multiphysics).

The final session began with another presentation by Zhou Qi, describing a method for modelling a random distribution of rods of different lengths, successfully using Matlab to generate MONK inputs for the specified distribution. The second presentation of the session was given by Derek Putley, looking at further developments to ICASPA. This methodology involves the automated generation of MONK inputs to solve an optimisation problem and is currently in use at EDF Energy. The final presentation of the day was given jointly by Simon Richards and Chris Baker, describing some recent queries that had been raised on the hotline regarding boundary conditions and temperature issues.

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