The Gen4 Module is a next generation design that uses a liquid metal cooled, uranium nitride fueled, fast-spectrum reactor that employs control rods for reactivity control. The reactor has been designed to deliver 70 MW of heat (25 MW of electricity) for a 10-year lifetime, without refueling.
Key advantages of the Gen4 Module design are:
- Advanced reactor design – Use of advanced reactor concepts provides for a safer and simpler reactor, elimination of many potential accident scenarios that affect LWRs, and elimination of complex reactor systems.
- Small reactor – A smaller reactor is more appropriately sized for smaller generation requirements, can directly replace existing diesel fueled generators, and requires no upgrade to existing small electricity distribution systems.
- 10-year power module replacement – The Gen4 Module provides 25 MWe continuously for 10 years on its initial fuel load (compared to an 18 to 24 month cycle for current light water reactors). No on-site refueling is required. After 10 years the entire reactor module is replaced.
- Underground containment vault – The reactor is sited in an underground containment vault to provide isolation from the environment, prevent intrusion or tampering, and avoid harm from natural disasters.
- Factory-assembled transportable power modules – Factory assembly allows for standard designs, superior quality control, and faster construction and on-site deployment.
A standardized design will offer several advantages:
- Manufacturing process controls will be uniform and will not vary between units.
- Nuclear fabrication and assembly will be completed at the factory before the unit is shipped, minimizing the nuclear construction capabilities that are necessary on site.
- On site construction activities will be limited to the reactor vault, the non-nuclear systems, placement of the Gen4 Module in the vault, and connection to the Gen4 Module to non-nuclear systems and controls. This will significantly reduce the on-site construction complexity and result in a faster construction schedule.
- Gen4 Energy will provide standard operating procedures, operator training, licensing support, technical support, in-service engineering, and safety analysis, significantly reducing the nuclear expertise and staffing that is required of the owner/operator.
Key material selections include:
- Lead Bismuth Eutectic (LBE) coolant -The core coolant is LBE, which is non-reactive to air and water, with a mixed mean exit temperature of 500C. A solid phase oxygen control system is used to control the oxygen level in the coolant to maintain a protective coating on structural surfaces, limiting corrosion.
- Uranium Nitride (UN) fuel- The fuel consists of 19.75% enriched (non weapons grade) UN pellets contained in clad tubes made of HT-9. These high-temperature ceramic material pellets deter the ability to separate plutonium from spent fuel.
- Stainless Steel structural materials (HT-9 and T-91)
- Quartz radial reflector
- B4C control rods for reactivity control -There are three independent reactivity shut-down systems in the core: a shutdown rod system composed of six boron carbide (B4C) rods, a control rod system comprising 12 boron carbide (B4C) rods and a reserve shutdown system consisting of a central cavity into which B4C balls may be inserted. Each of the three systems can independently take the core to long-term cold shutdown. The rod shutdown and the ball shutdown systems perform this safety function automatically and instantaneously when triggered.