Conceptual design of a lead-bismuth cooled fast reactor with in-vessel direct-contact steam generation

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 2001.Includes bibliographical references (p. 357-366).The feasibility of a lead-bismuth (Pb-Bi) cooled fast reactor that eliminates the need for steam generators and coolant pumps was explored. The working steam is generated by direct contact vaporization of water and liquid metal in the chimney above the core and then is sent to the turbine. The presence of a lighter fluid in the chimney drives the natural circulation of the Pb- Bi within the reactor pool. Three key technical issues were addressed: 1) the maximum thermal power removable by direct contact heat transfer without violating the fuel, clad and vessel temperature limits, 2) the consequences of Pb-Bi aerosol transport on the design and operation of the turbine and 3) the release of radioactive polonium (a product of coolant activation) to the steam. Modeling of the multi-phase phenomena occurring in the chimney confirmed the effectiveness of the direct contact heat transfer mode within a well-defined design envelope for the reactor power, chimney height and steam superheat. A 1260MWth power is found possible for 10m chimney height and 25°C superheat. The temperature of the low-nickel steel clad is maintained below 600°C, which results in limited corrosion if tight control of the coolant oxygen concentration is adopted.Generation, transport and deposition of Pb-Bi aerosols were also modeled. It was found that the design of a chevron steam separator reduces the heavy liquid metal in the steam lines by about three orders of magnitude. Nevertheless, the residual Pb-Bi is predicted to cause embrittlement of the turbine blades. Four solutions to this problem were assessed: blade coating, employment of alternative materials, electrostatic precipitation and oxidation of the Pb-Bi droplets. An experimental campaign was conducted to investigate the polonium release from a hot Pb- Bi bath to a gas-streamn. Th thermodynamics of the polonium hydride formation reaction (free- energy vs. temperature). as welQ as the vapor pressure of the lead-polonide were measured and then utilized to model the polonium transport in the reactor. It was found that the polonium concentration in the steam and on the surface of the power cycle components is significantly above the acceptable limits, which makes the very concept of a direct contact reactor open to question.by Jacopo Buongiorno.Ph.D

Thermal Hydraulics in Nuclear Power Technology

Advanced topics emphasizing thermo-fluid dynamic phenomena and analysis methods. Single-heated channel-transient analysis. Multiple-heated channels connected at plena. Loop analysis including single and two-phase natural circulation. Kinematics and dynamics of two-phase flows with energy addition. Boiling, instabilities, and critical conditions. Subchannel analysis. From the course home page: Course Description This course covers the thermo-fluid dynamic phenomena and analysis methods for conventional and nuclear power stations. Specific topics include: kinematics and dynamics of two-phase flows; steam separation; boiling, instabilities, and critical conditions; single-channel transient analysis; multiple channels connected at plena; loop analysis including single and two-phase natural circulation; and subchannel analysis. Starting in Spring 2007, this course will be offered jointly in the Departments of Nuclear Science and Engineering, Mechanical Engineering, and Chemical Engineering, and will be titled "Thermal Hydraulics in Power Technology.

Engineering of Nuclear Reactors

Engineering principles of nuclear reactors, emphasizing power reactors. Power plant thermodynamics, reactor heat generation and removal (single-phase as well as two-phase coolant flow and heat transfer), and structural mechanics. Engineering considerations in reactor design. From the course home page: Course Description This course covers engineering principles of nuclear reactors, emphasizing power reactors. Topics include power plant thermodynamics, reactor heat generation and removal (single-phase as well as two-phase coolant flow and heat transfer), and structural mechanics. Engineering considerations in reactor design are also covered. The course objective is to understand and model the thermal-hydraulic and mechanical phenomena key to the effective, reliable and safe design and operation of nuclear systems. This course is taught by Prof. Jacopo Buongiorno. More information is available on his Web site