Introduction to Work Package 4 Safety and Performance for a New Generation of Reactor Designs Tony Goddard Applied Modelling and Computation Group Earth Science and Engineering Imperial College London

Initial Aims and Objectives PhD and PDRA training in systems modelling with respect to Gen IV Research into modelling fault and severe accident transient behaviour of VHTR and GFR systems Link materials performance and detailed heat transfer processes into safety performance research Develop the ability to predict the dynamical behaviour of fission products To form an overview of hydrogen production using nuclear heat from advanced reactors and comment on design implications To work closely with UK industry and international bodies Identify gaps in knowledge to supplement the UK contribution to the international programme

Investigators and Projects ‘Strong cross cutting (CC) with other WPs’ Chris Pain and Tony Goddard (Imperial, CC with WP1) Coupled 3D asymmetric neutronics/thermal hydraulics for Gen IV fault studies Multi-scale physics and fluids modelling … to perform 3D whole core spatially coupled transient studies for a range of faults for VHTR and GFR models… will use the generic advanced reactor FETCH option implemented.. with a primary research focus on … the physics and engineering of …selected fault and severe accident sequences. Dominique Laurence and Mark Cotton (Manchester, CC with WP1) Heat transfer in advanced ceramic structures A PhD student will exploit the database … of advanced RANS models.. focus on optimising fuel/coolant exchanges for novel VHTR-GFR (gas-cooled) ceramic-prismatic cells in future reactor designs… explore a variety of innovative designs, such as spiral ribs, or twisted hexagonal rods

Investigators and Projects Robin Grimes (Imperial, CC with WP3) Radiation damage simulations in fuel … develop the ability to predict the dynamical evolution of fission products in fuel and waste forms subject to displacement damage. …will employ conventional molecular dynamics and a new multi-time scale simulation approach…. underpinning …..reactor safety case models for the release of volatile fission products (in particular gas atoms) from fuel. Barry Marsden (Manchester, CC with WP2) Graphite issues for Generation IV To obtain a core life to ~40years as required under Generation IV aims new longer lasting graphite needs to be developed for VHTR technology.. This will involve the development of mechanistic models that may be used to predict the irradiation behaviour of new novel graphitic material from knowledge of the unirradiated microstructure.

Investigators and Projects Mike Fitzpatrick and Lyndon Edwards (OU, CC WP2) Review of candidate metallic materials. … a very good understanding of the behaviour of the materials (static and dynamic) is required over the entire scale range from atomic, through micro-structure, to large scale structures.. the OU will review international work, identify gaps in knowledge Ray Allen (Sheffield) Design implications of hydrogen production A Generation IV reactor, such as the VHTR, is considered an essential element of the international drive to harness nuclear heat for the zero emission production of hydrogen…., the Sheffield team will consider in detail the thermodynamic limitations of the available cycles and the extent to which these impact on the reactor design, particularly in so far as it places limits on the upper temperature for process use.

Features of activity since October 2005 Held two WP meetings (hosted Barry) in Manchester – Spring 2006 and 2007 Meetings useful for new ideas – eg KNOO cfd benchmarking activity Good forum for PhD students – supplemented by: –six young people attended Stuttgart Raphael VHTR course –Three attended FJ/OH course last year and two to attend 2007 GenIV systems excellent for originality and research training UK becoming ‘inactive’ GIF member has hit stakeholders Nonetheless – wider spin-offs for stakeholders from KNOO

Examples of wider UK industry spin-offs Increases pool of people familiar with gas reactor issues – eg graphite materials issues, whole circuit modelling – MACE code – and coolant channel flows ‘virtual’ reactor – KNOO WP4 3D coupled nuclear/T/H/structural modelling provides supportive platform for collaboration with SULTAN/MOD reactor research

Relations with EC etc The commission now has robust frameworks for indirect action programmes for all six GenIV systems under FP7 We have ensured that senior figures in the Commission and EURATOM are aware of KNOO – they want closer contacts Need for a UK ‘legal entity’ which could bring KNOO within GIF – better international contacts for our training and research? Only current formal route to GIF is participation in FP6/FP7 indirect action programmes – several KNOO groups have these links

For our student audience What are the GenIV systems? Compared with Gen III, (~2015), Gen IV systems (~2040) enhanced sustainability (including full actinide recycling) and enhanced competitiveness (eg cogeneration of heat and power for process heat, syn-fuels and hydrogen)

For our student audience GenIV thermal systems VHTR – mainly possible co-generation, maybe electricity production with high efficiency, no actinide management, once through cycle SCWR – Supercritical water-cooled reactor – mainly electricity production with high efficiency, maybe cogeration, actinide management with ‘fast’ version.

For our student audience GenIV fast systems – and MSR GFR – Mainly electricity production with high efficiency/actinide management SFR – as for GFR LFR - as for GFR MSR- Molten salt reactor – full actinide management; electricity production – also MSR research links with advanced reprocessing technology

Summary WP 4 off to a good start with good inter-university relations and links between WPs Exciting new research areas emerging Gen IV clearly a major research activity in Europe and we need to find better ways to interact with this and with GIF Spin-offs to current UK industry interests