3D Coupled Fault Modelling for the Gas-cooled Fast Reactor

Jason Dunstall

KNOO PhD Student

(EPSRC Funded)

Applied Modelling and Computation Group (AMCG)

Dept. Earth Sciences & Engineering

Supervisors: Prof. C. Pain, Prof. A. Goddard

KNOO Post-Doc. Support: Dr J Gomes

Presentation overview

• The Gas-cooled Fast Reactor– What is the GFR

– Why is it of interest?

– Background of HTRs

– AMCG involvement with GFR

• Dragon Reactor Experiment– Background to the DRE

– Benchmarking work using Dragon

What is the GFR?

• Gas-cooled Fast Reactor - one of six Generation IV innovative reactor systems

• Design specifications:– He cooled

– Carbide or nitride fuel

– Zr3Si2 reflector, B4C shield

– 600 / 2400 MWth designs

– Power density ~100 MWth / m3

– ~ 850°C outlet temperature (direct cycle)

Strengths of the GFR

• Incorporation of passive safety features– Helium chemically inert, nearly neutronically inert, single phase– Favourable reactivity coefficients

• Sustainability– High U utilisation, actinide management, integrated fuel cycle

• High temperature reactor – Improved thermal efficiency, potential for use of process heat

• But: high fuel rating, lack of moderation → cooling and control issues

Technology base for GFR

• Decommissioned reactors include:– Dragon (International / UK sited)– AVR, THTR (Germany)– Peach Bottom, Fort St. Vrain (USA)– Fast reactors inc. DFR / PFR (UK), Superphenix (France)

• Extensive UK experience from AGRs

• Current and future projects include:• HTTR (Japan) • HTR-10 (China) • PBMR (South Africa)• GT-MHR (Russia / General Atomics)• ETDR (~2015)

AMCG work on GFR

• AMCG Codes:– EVENT (radiation transport)

– FLUIDITY (CFD)

– FETCH (coupled radiation-fluids interface code)

• Perform multiphysics analysis on GFR designs

• Potential for cross-cutting with VHTR - fuels & materials.

Background to Dragon

• Dragon Reactor Experiment– OECD / NEA International collaboration– Operational 1964-75, Winfrith, Dorset– World’s first HTR

• Testbed for HTR technology:– Fuel (TRISO particles)– Use of Helium coolant – Materials under HTR conditions

• Physics description:– 1.5m3 core volume– Inlet temperature ~350°C, outlet ~750°C– Normal peak core temperature ~1200°C

Dragon – some pictures

Modelling the DRE (1)

• Modelling the DRE: HTR benchmarking with FETCH– Reactivity measurements

– Neutron fluxes & power distributions

– Transients

EVENT Model:– 71650 nodes

– 75927 surface

– & volume elements

Fuel (I)Fuel (II)Inner ReflectorControl Rod RegionOuter Reflector

Modelling the DRE (2)

• Example – Dragon first charge loading reactivity measurements

and EVENT transport calculation results

Dragon experimental (solid line) EVENT transport calculations

Future PhD work for GFR

• GFR (600 and / or 2400 MW) model in EVENT - benchmarking

• Detailed multiphysics analysis using FETCH

• 3D asymmetrical transients & accident scenarios including:– Control rod movement

– Structural faults

– Depressurisations

– UTOP

Summary

• Use of well documented Dragon experiment for benchmarking of FETCH

• Need for comprehensive awareness of materials, thermal hydraulics and control issues for GFR

• Address use of fast spectrum cross section data

• Plan to perform detailed GFR coupled transient fault studies