Pavel V. Tsvetkov

Fast spectrum reactors

Fast Spectrum Reactors presents a detailed overview of world-wide technology contributing to the development of fast spectrum reactors. With a unique focus on the capabilities of fast spectrum reactors to address nuclear waste transmutation issues, in addition to the well-known capabilities of breeding new fuel, this volume describes how fast spectrum reactors contribute to the wide application of nuclear power systems to serve the global nuclear renaissance while minimizing nuclear proliferation concerns. Readers will find an introduction to the sustainable development of nuclear energy and the role of fast reactors, in addition to an economic analysis of nuclear reactors. A section devoted to neutronics offers the current trends in nuclear design, such as performance parameters and the optimization of advanced power systems. The latest findings on fuel management, partitioning and transmutation include the physics, efficiency and strategies of transmutation, homogeneous and heterogeneous recycling, in addition to valuable fuel cycle results. The systems section covers fuel pin and assembly design, fuel pin performance, overall systems considerations, and a major chapter on core materials where advances in metal fuels and long-life structural capabilities are featured. The safety section includes both traditional safety analysis techniques as well as a perspective on methods to achieve passive safety response. Whereas the bulk of the book is focused on sodium-cooled fast spectrum systems, a final section features gas-cooled and lead-cooled fast reactor systems

Supercritical CO2 direct cycle Gas Fast Reactor (SC-GFR) concept.

This report describes the supercritical carbon dioxide (S-CO{sub 2}) direct cycle gas fast reactor (SC-GFR) concept. The SC-GFR reactor concept was developed to determine the feasibility of a right size reactor (RSR) type concept using S-CO{sub 2} as the working fluid in a direct cycle fast reactor. Scoping analyses were performed for a 200 to 400 MWth reactor and an S-CO{sub 2} Brayton cycle. Although a significant amount of work is still required, this type of reactor concept maintains some potentially significant advantages over ideal gas-cooled systems and liquid metal-cooled systems. The analyses presented in this report show that a relatively small long-life reactor core could be developed that maintains decay heat removal by natural circulation. The concept is based largely on the Advanced Gas Reactor (AGR) commercial power plants operated in the United Kingdom and other GFR concepts.

Accelerator-driven subcritical fission in molten salt core: Closing the nuclear fuel cycle for green nuclear energy

A technology for accelerator-driven subcritical fission in a molten salt core (ADSMS) is being developed as a basis for the destruction of the transuranics in used nuclear fuel. The molten salt fuel is a eutectic mixture of NaCl and the chlorides of the transuranics and fission products. The core is driven by proton beams from a strong-focusing cyclotron stack. This approach uniquely provides an intrinsically safe means to drive a core fueled only with transuranics, thereby eliminating competing breeding terms.

Planetary Surface Power and Interstellar Propulsion Using Fission Fragment Magnetic Collimator Reactor

Fission energy can be used directly if the kinetic energy of fission fragments is converted to electricity and/or thrust before turning into heat. The completed US DOE NERI Direct Energy Conversion (DEC) Power Production project indicates that viable DEC systems are possible. The US DOE NERI DEC Proof of Principle project began in October of 2002 with the goal to demonstrate performance principles of DEC systems. One of the emerging DEC concepts is represented by fission fragment magnetic collimator reactors (FFMCR). Safety, simplicity, and high conversion efficiency are the unique advantages offered by these systems. In the FFMCR, the basic energy source is the kinetic energy of fission fragments. Following escape from thin fuel layers, they are captured on magnetic field lines and are directed out of the core and through magnetic collimators to produce electricity and thrust. The exiting flow of energetic fission fragments has a very high specific impulse that allows efficient planetary surface power an...

Integrated Multi-Modular Fast Reactor Concept Design

The Integrated Multi-Modular Fast reactor is a pre-conceptual small modular fast reactor design consisting of 7 self-consist subcritical modules, each utilizing a BeO-MOX concept fuel with complete supercritical CO2 brayton cycle turbo-machinery. The subcritical modules, when brought into proximity of one another, form a complete critical reactor core. The feasibility of the reactor is assessed on a full core level, which includes a neutronics, thermal hydraulics, balance of plant, economics, and economics analysis. It has been shown that a critical configuration lasting for 14 years at 10 MWth can be achieved. A hot channel thermal hydraulics and safety analysis shows that the reactor can operate within safety limits with negative temperature coefficients of reactivity as well as stay within fuel temperature limits. A plant thermal efficiency of 36% was achieved and there is room for optimization to achieve higher efficiencies. An economical feasibility assessment shows that the reactor can be economical based on an economy of serial production argument. The analysis also leads to a licensing discussion.Copyright

Autonomous Corium Reactor for Terrestrial Applications

Current reactors utilize complex systems for safety and operation. The proposed design concept employs metal fuel in a molten state, within a silicon carbide crucible. It takes advantage of physics features to ensure safe reactor operation without human intervention. This molten fuel concept provides large thermal feedback in the fuel due to strong temperature dependent thermophysical properties. Fuel boiling phenomena potentially allows for fuel mass relocation/removal to isolated condensation regions to ensure a critical geometry throughout life. The strong tendency for natural circulation in liquid metals suggests a lead-based coolant to provide load following capability. A reactor meltdown becomes a normal operational state ensuring that core damage is minimized. Preliminary calculations show favorable reactor behavior and control at 100MWt; however, material compatibility and alloy integrity have not been studied. The reactor concept minimizes the need for human involvement in reactor operation, reduces the complexity of supporting systems, and can be deployed remotely for terrestrial thermal power and battery needs for periods greater than 25 years.Copyright

Introductory Design Considerations

Before discussing the neutronics, systems, and safety considerations involved in designing fast spectrum reactors, it is appropriate to follow the lead of Wirtz [1] in sketching the bases for fast spectrum reactor designs. In this orientation, care will be taken to indicate the principal differences relative to thermal reactor systems with which the reader is more likely familiar. This introduction to design begins with a brief discussion of major design objectives, followed by an overview of the mechanical and thermal systems designs of fast spectrum reactors (with an emphasis in this chapter on fast breeder reactors, since most other applications of fast spectrum systems—such as waste transmutation—will be optimized if the reactor has a high internal conversion ratio and/or a high breeding ratio). Because of the position occupied by the sodium-cooled fast reactor (SFR) in the international fast spectrum reactor community, that system will be used for purposes of illustration.

Used Fuel Vectors and Waste Minimization Strategies for VHTRS Operating Without Refueling

Abstract Generation IV Very High Temperature Reactors (VHTRs) are well-known for their flexibility with respect to feasible fuel cycle options. In this paper, the LEU- and TRU-fueled VHTR configurations are analyzed accounting for their capabilities to attain an extended single-batch OTTO (Once-Through-Then-Out) mode of operation without intermediate refueling. The requirement of waste minimization is imposed as one of the design constraints defining possible system configurations and deployment strategies. The resulting “used fuel” vectors are examined considering anticipated disposal options as well as viability of fuel reprocessing. A Monte Carlo-deterministic analysis methodology has been implemented for coupled design studies of VHTRs with TRUs using the ORNL SCALE 5.1 code system. The developed modeling approach provides an exact-geometry 3D representation of the VHTR core details properly capturing VHTR physics. The presented analysis is focused on prismatic block core concepts for VHTRs. It is being performed within the scope of the U.S. DOE NERI project on utilization of higher actinides (TRUs and partitioned MAs) as a fuel component for extended-life VHTR configurations.

Benchmark Efforts to Support Studies of Advanced VHTRs

The Very High Temperature Reactor (VHTR) is the leading candidate for the reactor component of the Next Generation Nuclear Plant (NGNP). This is because the VHTR demonstrates great potential in improving safety characteristics, being economically competitive, providing a high degree of proliferation resistance, and producing high outlet temperatures for efficient electricity generation and/or other high temperature applications, most notably hydrogen production. In addition, different fuel types can be utilized by VHTRs, depending on operational goals. In this case, the recovery and utilization of the valuable energy left in LWR fuel in order to create ultra long life single batch cores by taking advantage of the properties of TRU fuels. This paper documents the initial process in the study of TRU fueled VHTRs, which concentrates on the verification and validation of the developed whole-core 3D VHTR models. Many of the codes used for VHTR analysis were developed without a full appreciation of the importance of randomness in particle distribution. With this in mind, the SCALE code system was chosen as the computational tool for the study. It provides the opportunity of utilizing SCALE versions 5.0 and 5.1, making it possible to compare and analyze different techniques accounting for the double heterogeneity effects associated with VHTRs. Startup physics results for Japan’s High Temperature Test Reactor (HTTR) were used for experiment-to-code benchmarking. MCNP calculations were employed for code-to-code benchmarking. Results and analysis are included in this paper.Copyright

A greedy memetic algorithm for a multiobjective dynamic bin packing problem for storing cooling objects

In this paper, a multiobjective dynamic bin packing problem for storing cooling objects is introduced along with a metaheuristic designed to work well in mixed-variable environments. The dynamic bin packing problem is based on cookie production at a bakery, where cookies arrive in batches at a cooling rack with limited capacity and are packed into boxes with three competing goals. The first is to minimize the number of boxes used. The second objective is to minimize the average initial heat of each box, and the third is to minimize the maximum time until the boxes can be moved to the storefront. The metaheuristic developed here incorporated greedy heuristics into an adaptive evolutionary framework with partial decomposition into clusters of solutions for the crossover operator. The new metaheuristic was applied to a variety benchmark bin packing problems and to a small and large version of the dynamic bin packing problem. It performed as well as other metaheuristics in the benchmark problems and produced more diverse solutions in the dynamic problems. It performed better overall in the small dynamic problem, but its performance could not be proven to be better or worse in the large dynamic problem.