GT-MHR design

As described above a major focus of the GT-MHR design and development in the last year was the PCS. However, progress was made in a number of other areas. 

The objective of the review and subsequent report (Ref. 6) was to provide the reactor designers and other organizations with interest in future electric power generating options with an independent evaluation of the conceptual GT-MHR design from the viewpoint of potential owner/operators. The review focused on the PCS. Two paragraphs from the summary are reproduced below from their report. 

Neylan, A. J., A. Shenoy, F. A. Silady, and T. D. Dunn, GT-MHR Design, Performance, and Safety, GA-A21924, Presented at the IAEA Technical Committee Meeting on Development Status of Modular High Temperature Reactors and Their Future Role, November 28-30, 1994, ECN, Petten, The Netherlands. 

The GT-MHR design directly couples the reactor with a turbogenerator in a closed helium Brayton cycle to produce electricity with 48% net plant efficiency. This high efficiency and the expansion of the power output to 600 MW(t) within the existing GT-MHR physical envelope results in a substantial reduction in the busbar power costs compared to the steam cycle modular helium reactors. The power generation costs are forther reduced by the simplified operation and maintenance required of the gas turbine plant, as compared to the steam cycle plant with its much more complicated balance of plant. 

The latest evolution made for the purpose of economics has been replacement of the Rankine steam cycle PCS with a high-efficiency Brayton (gas turbine) cycle PCS to boost the thermal conversion efficiency to -48%. The coupling of the MHR with the gas turbine cycle forms the GT-MHR. The GT-MHR retains all of the MHR passive safety characteristics but is projected to have more attractive economics than any other generation alternative (Shenoy 1996). The organization behind the MHR and GT-MHR designs is General Atomics (GA). 

Applications - Cogeneration applications, including electricity generation and process heat production -Potable water and hydrogen production are being considered - Pu utilization (GT-MHR design for the Russian Federation) - 2001 of H2 per day at 600 MW(th) or - Electricity plus 42 000 mVday of potable water at 600 MW(th) - Low temperature heat applications... 

The development and deployment of commercial GT-MHRs is based upon leveraging an ongoing international project to develop and deploy a multi-module GT-MHR designed to consume excess weapons grade plutonium in the Russian Federation, see Annex XV. 

Development of the GT-MHR has already benefited substantially from international cooperation on research and development. The following coordinated research projects (CRPs) conducted by the IAEA in the 1990s have resulted in exchanges of technical data and analyses that have advanced the GT-MHR design and reduced development risks ... 

A prismatic block core, with fuel and reflector blocks essentially identical to the GT-MHR design, was built and operated to power the Fort St. Vrain generating station. Open cycle gas turbines are operating at temperatures enveloping the GT-MHR conditions. Component testing will provide additional experience and understanding in areas not covered by Fort St. Vrain and open cycle gas turbines. However, Fort St. Vrain differed from the GT-MHR in important aspects (e.g. use of a pre-stressed concrete reactor vessel vs. a steel reactor vessel. 

The reactor for the MHR-T RP is designed on the basis of the GT-MHR reactor concept. The main reactor equipment is arranged in a vertical vessel located parallel to the power conversion unit and high-temperature heat exchanger vessels in a separate cavity. 

A follow-up design is given in the GT-MHR (Modular Helium Reactor) (see also section 4.7.2.) with a higher power output of 600 MW(th). A standard plant is planned consisting of four of those units. Helium inlet/outlet temperatures are 485 and 850 °C, respectively. The cycle efficiency is predicted to be 47 % [51]. Follow-on evaluations which need to be done include the study of transient response of plant components to normal and off-normal events, impact of turbine contamination, and confirmation of plant efficiency [47]. 

GT--MHR project is a joint Russian-American design of the nuclear power plant with direct gas turbine cycle. 

This paper updates the design status of the GT-MHR with emphasis on the PCS. Section 2 reports on the trade study that addressed the question of whether the generator should be submerged in helium within the power conversion vessel or be external to the vessel necessitating a... 

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