Nuclear Power Feasibility 2007

Nuclear power is a proven technology and has the potential to generate virtually limitless energy with no significant greenhouse gas emissions. Nuclear power can become one of the main options to contribute to substantial cuts in global greenhouse gas emissions. Modern development of nuclear power technology and the established framework of international agreements and conventions are responding to the major political, economic and environmental issues -high capital costs, the risks posed by nuclear waste and accidents, and the proliferation of nuclear weaponry- that until recently hindered the expansion of nuclear power. In response to such prospects, the WFEO Energy Standing Committee set up a Task Group to develop this Report on NUCLEAR POWER FEASIBILITY - 2008. This Report gathers information on the state-of-the-art of nuclear energy technology and its current technical and economic feasibility based on engineering criteria and technological maturity. Members of the Task Group were appointed by WFEO Member Organizations. This Report is being presented as a publication in the Energy Standing Committee Series on Feasibility of Current Energy Options. The Series is intended to give the viewpoint of the engineer on questions related to technical and economic feasibility of energy issues of significance to society. It aims at providing the engineer and decision making officers with updated information regarding the state-of-the-art of different technologies that are being used or are under consideration for the supply of energy

The Status of the US High-Temperature Gas Reactors

In 2005, the US passed the Energy Policy Act of 2005 mandating the construction and operation of a high-temperature gas reactor (HTGR) by 2021. This law was passed after a multiyear study by national experts on what future nuclear technologies should be developed. As a result of the Act, the US Congress chose to develop the so-called Next-Generation Nuclear Plant, which was to be an HTGR designed to produce process heat for hydrogen production. Despite high hopes and expectations, the current status is that high temperature reactors have been relegated to completing research programs on advanced fuels, graphite and materials with no plans to build a demonstration plant as required by the US Congress in 2005. There are many reasons behind this diminution of HTGR development, including but not limited to insufficient government funding requirements for research, unrealistically high temperature requirements for the reactor, the delay in the need for a “hydrogen” economy, competition from light water small modular light water reactors, little utility interest in new technologies, very low natural gas prices in the US, and a challenging licensing process in the US for non-water reactors

A future for nuclear energy: pebble bed reactors

Abstract: Pebble Bed Reactors could allow nuclear plants to support the goal of reducing global climate change in an energy hungry world. They are small, modular, inherently safe, use a demonstrated nuclear technology and can be competitive with fossil fuels. Pebble bed reactors are helium cooled reactors that use small tennis ball size fuel balls consisting of only 9 grams of uranium per pebble to provide a low power density reactor. The low power density and large graphite core provide inherent safety features such that the peak temperature reached even under the complete loss of coolant accident without any active emergency core cooling system is significantly below the temperature that the fuel melts. This feature should enhance public confidence in this nuclear technology. With advanced modularity principles, it is expected that this type of design and assembly could lower the cost of new nuclear plants removing a major impediment to deployment

Pebble flow experiments for pebble bed reactors

A series of one-to-ten-scale experiments were conducted at the Massachusetts Institute of Technology (MIT) to explore several key aspects of pebble flow in pebble-bed reactors. These experiments were done to assess not only the flow lines but also the relative velocities of the pebbles of various radii from the center line of the core. Half-model and full 3-D experiments were performed to verify that there were no surface effects that would affect the flow lines. In addition, an experiment was conducted to determine whether, for dynamic annular cores, the mixing zone could be eliminated greatly improving the capability of the core to produce power. An analysis was performed to establish the size of a ring to be inserted in the top of the core that would preclude the central graphite pebbles from bouncing out of the center region and fuel pebbles in the outer periphery from bouncing in. These experiments showed conclusively that the mixing zone could be effectively eliminated while maintaining the annular column during the recirculation process. The flow tests were performed under fast and slow flow conditions replicating the actual performance in a reactor.

Integration of Reactor Design, Operations, and Safety

This course integrates studies of reactor physics and engineering sciences into nuclear power plant design. Topics include materials issues in plant design and operations, aspects of thermal design, fuel depletion and fission-product poisoning, and temperature effects on reactivity, safety considerations in regulations and operations, such as the evolution of the regulatory process, the concept of defense in depth, General Design Criteria, accident analysis, probabilistic risk assessment, and risk-informed regulations

DESIGN AND LAYOUT CONCEPTS FOR COMPACT, FACTORY-PRODUCED, TRANSPORTABLE, GENERATION IV REACTOR SYSTEMS

The purpose of this research project is to develop compact (100 to 400 MWe) Generation IV nuclear power plant design and layout concepts that maximize the benefits of factory-based fabrication and optimal packaging, transportation and siting. The reactor concepts selected were compact designs under development in the 2000 to 2001 period. This interdisciplinary project was comprised of three university-led nuclear engineering teams identified by reactor coolant type (water, gas, and liquid metal) and a fourth Industrial Engineering team. The reactors included a Modular Pebble Bed helium-cooled concept being developed at MIT, the IRIS water-cooled concept being developed by a team led by Westinghouse Electric Company, and a Lead-Bismuth-cooled concept developed by UT. In addition to the design and layout concepts this report includes a section on heat exchanger manufacturing simulations and a section on construction and cost impacts of proposed modular designs

Modular Pebble Bed Reactor

This project is developing a fundamental conceptual design for a gas-cooled, modular, pebble bed reactor. Key technology areas associated with this design are being investigated which intend to address issues concerning fuel performance, safety, core neutronics and proliferation resistance, economics and waste disposal. Research has been initiated in the following areas: • Improved fuel particle performance • Reactor physics • Economics • Proliferation resistance • Power conversion system modeling • Safety analysis • Regulatory and licensing strategy Recent accomplishments include: • Developed four conceptual models for fuel particle failures that are currently being evaluated by a series of ABAQUS analyses. Analytical fits to the results are being performed over a range of important parameters using statistical/factorial tools. The fits will be used in a Monte Carlo fuel performance code, which is under development. • A fracture mechanics approach has been used to develop a failure probability model for the fuel particle, which has resulted in significant improvement over earlier models. • Investigation of fuel particle physio-chemical behavior has been initiated which includes the development of a fission gas release model, particle temperature distributions, internal particle pressure, migration of fission products, and chemical attack of fuel particle layers. • A balance of plant, steady-state thermal hydraulics model has been developed to represent all major components of a MPBR. Component models are being refined to accurately reflect transient performance. • A comparison between air and helium for use in the energy-conversion cycle of the MPBR has been completed and formed the basis of a master’s degree thesis. • Safety issues associated with air ingress are being evaluated. • Post shutdown, reactor heat removal characteristics are being evaluated by the Heating-7 code. • PEBBED, a fast deterministic neutronic code package suitable for numerous repetitive calculations has been developed. Use of the code has focused on scoping studies for MPBR design features and proliferation issues. Publication of an archival journal article covering this work is being prepared. • Detailed gas reactor physics calculations have also been performed with the MCNP and VSOP codes. Furthermore, studies on the proliferation resistance of the MPBR fuel cycle has been initiated using these code • Issues identified during the MPBR research has resulted in a NERI proposal dealing with turbo-machinery design being approved for funding beginning in FY01. Two other NERI proposals, dealing with the development of a burnup “meter” and modularization techniques, were also funded in which the MIT team will be a participant. • A South African MPBR fuel testing proposal is pending ($7.0M over nine years)