Pavel Hejzlar

Flexible Conversion Ratio Fast Reactor Systems Evaluation

Conceptual designs of lead-cooled and liquid salt-cooled fast flexible conversion ratio reactors were developed. Both concepts have cores reated at 2400 MWt placed in a large-pool-type vessel with dual-free level, which also contains four intermediate heat exchanges coupling a primary coolant to a compact and efficient supercritical CO2 Brayton cycle power conversion system. Decay heat is removed passively using an enhanced Reactor Vessel Auxiliary Cooling System and a Passive Secondary Auxiliary Cooling System. The most important findings were that (1) it is feasible to design the lead-cooled and salt-cooled reactor with the flexible conversion ratio (CR) in the range of CR=0 and CR=1 n a manner that achieves inherent reactor shutdown in unprotected accidents, (2) the salt-cooled reactor requires Lithium thermal Expansion Modules to overcme the inherent salt coolants large positive coolant temperature reactivity coefficient, (3) the preferable salt for fast spectrum high power density cores is NaCl-Kcl-MgCl2 as opposed to fluoride salts due to its better themal-hydraulic and neutronic characteristics, and (4) both reactor, but attain power density 3 times smaller than that of the sodium-cooled reactor.

Compressor Design for the Supercritical CO2 Brayton Cycle

C, with a cycle efficiency of 45%. Turbomachinery used in the cycle is composed of two compressors (a main compressor and a recompressing compressor) and a turbine, which work on a single shaft. In fact the high cycle efficiency is realized by having the main compressor operate near the critical point of CO2 to benefit from reduced compression work. Introduction of the recompressing compressor which operates at a temperature higher than critical is to avoid the pinch-point problem which otherwise occurs in the subsequent recuperator. Because the perfect gas law does not apply near the saturation line, CO2 was treated as a real gas and the NIST property database was used for the purpose of CO2 thermodynamics and transport property evaluation. The preliminary design process for the supercritical CO2 compressors is mainly discussed in this paper. Steady-state design as well as off-design analysis was performed using the AXIAL TM program modified for real gas properties. The results show that the supercritical CO2 compressors are more compact than helium compressors, with equivalent adiabatic efficiency.

gothic code evaluation of alternative passive containment cooling features

Abstract Reliance on passive cooling has become an important objective in containment design. Several reactor concepts have been set forth, which are equipped with entirely passively cooled containments. However, the problems that have to be overcome in rejecting the entire heat generated by a severe accident in a high-rating reactor (i.e. one with a rating greater than 1200 MW e ) have been found to be substantial and without obvious solutions. The GOTHIC code was verified and modified for containment cooling applications; optimal mesh sizes, computational time steps and applicable heat transfer correlations were examined. The effect of the break location on circulation patterns that develop inside the containment was also evaluated. The GOTHIC code was then employed to assess the effectiveness of several original heat rejection features that make it possible to cool high-rating containments. Two containment concepts were evaluated: one for a 1200 MW e new pressure tube light-water reactor, and one for a 1300 MW e pressurized-water reactor. The effectiveness of various containment configurations that include specific pressure-limiting features has been predicted. The best-performance configurations-worst-case-accident scenarios that were examined yielded peak pressures of less than 0.30 MPa for the 1200 MW e pressure tube light-water reactor, and less than 0.45 MPa for the 1300 MW e pressurized-water reactor.

Engineering and Physics Optimization of Breed and Burn Fast Reactor Systems

This project is organized under four major tasks (each of which has two or more subtasks) with contributions among the three collaborating organizations (MIT, INEEL and ANL-West): Task A: Core Physics and Fuel Cycle; Task B: Core Thermal Hydraulics; Task C: Plant Design Task; and D: Fuel Design.

Letter to the editor on the paper by D.C. Groeneveld and L.K.H. Leung, “The 1995 look-up table for critical heat flux in tubes”

Abstract This letter gives a brief critique of the new 1995 Look-Up-Table for critical heat flux (CHF). Issues on Look-Up-Table statistics, table usage and CHF values for critical flow are highlighted.

A computer program for transient analysis of steam turbine generator overspeed

Abstract One of the most important conditions for safe turbine generator operation is protection against turbine overspeed. A mathematical model is presented which enables the analysis of transient processes with variable revolutions of a turbine-generator following the disconnection of the generator from the electrical grid. The model provides the capability to generate an arbitrary turbine generator system through input data and to simulate system behavior in time. The main building blocks of the model include high and low pressure turbines, a moisture separator, a reheater, a condenser, feedwater heaters, a deaerator, pumps, and control valves. The model is built on the lumped-parameter approach. The turbine-generator system is described by a set of control volumes interconnected by junctions. Control volumes are represented by time dependent energy and mass conservation equations; junctions are described by quasi-steady momentum equations. The overall approach of the model is demonstrated for a 220 MWe steam turbine for nuclear power plants. The model description is concentrated primarily on the turbine generator. Comparison of the model with experimental data obtained for a 220 MWe turbine shows very good agreement.

Engineering and Physics Optimization of Breed and Burn Fast Reactor Systems; NUCLEAR ENERGY RESEARCH INITIATIVE (NERI) QUARTERLY PROGRESS REPORT

This project is organized under four major tasks (each of which has two or more subtasks) with contributions among the three collaborating organizations (MIT, INEEL and ANL-West): Task A: Core Physics and Fuel Cycle; Task B: Core Thermal Hydraulics; Task C: Plant Design; Task D: Fuel Design The lead PI, Michael J. Driscoll, has consolidated and summarized the technical progress submissions provided by the contributing investigators from all sites, under the above principal task headings.

Western and Asian light water reactors at the millennium threshold

Abstract This paper presents the most advanced Western and Asian light water reactor (LWR) designs. The following pressurized water reactor (PWR) and boiling water reactor (BWR) designers are covered: Westinghouse ( W ), Babcock and Wilcox (B&W—now part of Framatome), Combustion Engineering (CE—now ABB CE), Siemens (PWR), Framatome, Mitsubishi, General Electric (GE), Asea Brown Boveri (ABB), Siemens (BWR), Hitachi and Toshiba. The motivations that led to the design of the next generation of LWRs are discussed. The technical bases for evolutionary and innovative plants are summarized. Important safety features of some of the most complete (in operation, under construction or certified) evolutionary designs are described detail. Analogous implementations of systems into other advanced designs are given.