钍基熔盐核能系统 Safety analysis of graphite core in molten salt test reactor Derek Tsang SINAP

Introduction  The Chinese Academy of Sciences (CAS) has launched a Thorium Molten Salt Reactor (TMSR) research project in  350M USD for 5 years  To develop generation IV molten salt reactors.  Multipurpose applications of high temperature nuclear energy.  To build two molten salt test reactors between 2015 and  A CAS center for TMSR research has been set up at the Shanghai Institute of Applied Physics (SINAP) to lead the project.

SINAP has a light source: Shanghai Synchrotron Radiation Facility (SSRF) 150 MeV Linear accelerator. 3.5 GeV Booster, 180m circumference 3.5 GeV Storage Ring, 432m circumference Number of Cells = 20

Introduction  Two types of molten salt reactors:  Molten salt and molten salt-cooled reactor.  Molten salt reactors use salt as fuel and coolant  Molten salt-cooled reactors use TRISO fuel and salt as coolant only.  Molten salt reactors may have a fully closed fuel cycle, however, online reprocessing is challenging.  Molten salt-cooled reactors have a once-through fuel cycle, however, have high temperature and efficiency.

Molten salt coolant  Coolant salt has  Good thermal conductivity  High boiling point  Nuclear system can operate at much lower pressure than high temperature gas cooled reactor  High melting point  Trap fission products in an accident  Large heat capacity  During accident the temperature of the core rises slowly

10MW salt-cooled test reactor  TMSR SF1  Built around 2015~2016  Aims:  To gain experiences on design, construction and operation  To validate models, analyses and codes  To test the equipment and safety features  To accumulate operation data for larger-size reactors design and licensing

10MW salt-cooled test reactor  TRISO is used as nuclear fuel  6cm diameter fuel pebbles  Graphite is used as moderator and reflector  Primary coolant is FLiBe salt  Operating temperature is between 600  C and 650  C  Core dimensions is 2.6m(dia.) x 3.0m(h)

10MW salt-cooled test reactor

Challenges for the 10MW test reactor  Reactor licensing  No molten salt-cooled or molten salt reactor has been licensed in China before  The regulators in China have limited exposure to either molten salt-cooled or molten salt reactor.  Stress analysis  Material properties  Irradiation data

Graphite stress analysis  Density of graphite: 1.77g/cm 3  Density of molten salt: 1.99g/cm 3  Buoyant force acts on graphite bricks!  Graphite bricks must be constrained within the core!  Solid liquid interaction

Graphite problems  Molten salt may penetrate into graphite.  Modify graphite material properties?!?  How to measure Young’s modulus with molten salt at high temperature:  Dynamic method  Static method

Graphite Irradiation program  Measure irradiated graphite material properties  Young’s modulus  CTE  Dimensional change  Thermal conductivity  Tensile strength  Compressive strength  With and without molten salt.

Graphite experiments  Shaking table 2m x 2m  Seismic test on graphite component