Very-high-Temperature Reactor

Presented By

Taher, Md Iktiham Bin (15-98378-1)Khan, Md Rabiul Islam (15-98279-1)Islam, Kazi Rashedul (15-98475-1)

Overview Of Our Presentation

What Is VHTR? Types Nuclear reactor design Advantages and Disadvantages Of VHTR Conclusion And Future Works

What Is VHTR? High-temperature gas-cooled reactor. The VHTR can produce hydrogen from only heat and water by using thermo-chemical

iodine-sulfur (I-S) process or from heat, water, and natural gas by applying the steam reformer technology to core outlet temperatures greater than about 1000°C.

Graphite-moderated nuclear reactor with a once-through uranium fuel cycle. The reactor core can be either a "prismatic block" or a "pebble-bed" core.

Types There are two types of Very-high-temperature reactors:

Pebble bed reactors (PBR) : The pebble bed reactor (PBR) design consists of fuel in the form of pebbles, stacked together in a cylindrical pressure vessel, like a gum-ball machine.

Prismatic block reactors (PMR): In which hexagonal graphite blocks are stacked to fit in a cylindrical pressure vessel.

Both reactors may have the fuel stacked in an annulus region with a graphite center spire, depending on the design and desired reactor power.

Nuclear reactor design Neutron moderator : The neutron moderator is graphite. Nuclear fuel : The fuel used in VHTRs is coated fuel particles, such as TRISO fuel particles. Coated fuel

particles have fuel kernels, usually made of uranium dioxide, however, uranium carbide or uranium oxycarbide are also possibilities.

Coolant: Helium, Molten salt.

Advantages and Disadvantages Of VHTRAdvantages Helium Coolant Thorium and Uranium Fuel Higher electric power efficiencies (>50%) Hydrogen production On-line Refueling

Disadvantages Fuel may not be rotated out when it needs to be Low thermal conductivity of Helium Limited research

Conclusion And Future WorksFollowing are the major areas of research and development to be focused in the future:

High temperature fuels – kernels and coatings (FP retention, integrity and higher burn-up);

Metallic components for structural power conversion; Fuel element design – minimum temperature drop between fuel and coolant; Air/water ingress effects on core/other materials; Control materials for elevated temperatures; Heat exchanger, recuperator materials and design, and vessel materials.

Thank you