Pebble bed modular reactor
Encyclopedia
The Pebble Bed Modular Reactor (PBMR) is a particular design of pebble bed reactor
under development by South Africa
n company PBMR (Pty) Ltd since 1994. The project entails the construction of a demonstration power plant at Koeberg near Cape Town (now postponed indefinitely) and a fuel plant at Pelindaba near Pretoria.
Heat from the PBMR can be used for a variety of industrial process applications, including process steam for cogeneration applications, in-situ oil sands recovery, ethanol applications, refinery and petrochemical applications. The high temperature heat can also be used to reform methane to produce syngas
(where the syngas can be used as feedstock to produce hydrogen, ammonia and methanol); and to produce hydrogen and oxygen by decomposing water thermochemically.
The PBMR is modular in that only small to mid-sized units will be designed. Larger power stations will be built by combining many of these modules. As of 2008, 400MWt was emerging as an optimum module size, considerably larger than the original concept size. The PBMR is fueled and moderated
by graphite fuel spheres each containing TRISO coated low enriched uranium oxide fuel particles. There are 15000 fuel particles per fuel sphere the size of a billiard ball. "Each fuel pebble contains 9 g of uranium, and this holds enough generation capacity to sustain a family of four, for a year. Five tons of coal and up to 23 000 m3 of water will be required to generate one pebble’s energy.”
The concept is based on the AVR reactor
and THTR in Germany, but modified to drive a Brayton cycle
turbine. The core is annular with a centre column as a neutron reflector
.
In 2009 PBMR (Pty) announced that it was looking at employing the technology for process heat applications , and some pebble bed reactor contracts had been put on hold to prevent unnecessary spending
In early 2010 the South Africa government announced it had stopped funding the development of the pebble bed modular reactor, and PBMR (Pty) stated it was considering 75% cuts in staff. The decision was taken because no customer or investor for PBMR was found. Unresolved technical items, a substantial increase of costs and a 2008 report from Forschungszentrum Jülich about major problems in operation of the German pebble bed reactor AVR had discouraged potential investors. International banks refused to support the PBMR project by loans. PBMRs CEO resigned on March, 8th 2010. In future, the South African nuclear program
will concentrate on conventional light water reactors.
On 25 May 2010 the company announced to staff that it intends to implement a "Care and Maintenance" Strategy. This involves the reduction of staff to 9. The stated purpose of the proposed structure is; preserve PBMR as a legal entity, preserve and optimize IP, preserve HTR license, preserve assets and solicit new investors. The strategy assumes that keeping on 9 employees in the medium term will leave sufficient funding to take PBMR to March 2013. The remaining employees will serve to end of October 2010. Some funding is foreseen for dismantling of the PBMR fuel fabrication laboratories in 2011.
In 2006, the US Department of Energy awarded the PBMR consortium the primary contract for the first phase of its New Generation Nuclear Plant (NGNP) project. The scope for the first phase of this contract, which has now been completed, was for the pre-conceptual engineering of a nuclear co-generation plant for the production of electricity and hydrogen. Requests for proposals for the second phase of the NGNP project will soon be issued, to which the PBMR consortium will be responding within the next few months of 2009. In May 2010 Westinghouse went out of the PBMR consortium, which led to an end of the South African engagement in NGNP.
Pebble bed reactor
The pebble bed reactor is a graphite-moderated, gas-cooled, nuclear reactor. It is a type of very high temperature reactor , one of the six classes of nuclear reactors in the Generation IV initiative...
under development by South Africa
South Africa
The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...
n company PBMR (Pty) Ltd since 1994. The project entails the construction of a demonstration power plant at Koeberg near Cape Town (now postponed indefinitely) and a fuel plant at Pelindaba near Pretoria.
Reactor design
Although it is not the only gas-cooled high-temperature reactor currently being developed in the world, the South African project is internationally regarded as the leader in the global power generation field. The PBMR is characterised by inherently safe features, which mean that no human error or equipment failure can cause an accident that would harm the public.Heat from the PBMR can be used for a variety of industrial process applications, including process steam for cogeneration applications, in-situ oil sands recovery, ethanol applications, refinery and petrochemical applications. The high temperature heat can also be used to reform methane to produce syngas
Syngas
Syngas is the name given to a gas mixture that contains varying amounts of carbon monoxide and hydrogen. Examples of production methods include steam reforming of natural gas or liquid hydrocarbons to produce hydrogen, the gasification of coal, biomass, and in some types of waste-to-energy...
(where the syngas can be used as feedstock to produce hydrogen, ammonia and methanol); and to produce hydrogen and oxygen by decomposing water thermochemically.
The PBMR is modular in that only small to mid-sized units will be designed. Larger power stations will be built by combining many of these modules. As of 2008, 400MWt was emerging as an optimum module size, considerably larger than the original concept size. The PBMR is fueled and moderated
Neutron moderator
In nuclear engineering, a neutron moderator is a medium that reduces the speed of fast neutrons, thereby turning them into thermal neutrons capable of sustaining a nuclear chain reaction involving uranium-235....
by graphite fuel spheres each containing TRISO coated low enriched uranium oxide fuel particles. There are 15000 fuel particles per fuel sphere the size of a billiard ball. "Each fuel pebble contains 9 g of uranium, and this holds enough generation capacity to sustain a family of four, for a year. Five tons of coal and up to 23 000 m3 of water will be required to generate one pebble’s energy.”
The concept is based on the AVR reactor
AVR reactor
The AVR reactor was a prototype pebble bed reactor at Jülich Research Centre in West Germany. Construction began in 1960, first grid connection was in 1967 and operation ceased in 1988....
and THTR in Germany, but modified to drive a Brayton cycle
Brayton cycle
The Brayton cycle is a thermodynamic cycle that describes the workings of the gas turbine engine, basis of the airbreathing jet engine and others. It is named after George Brayton , the American engineer who developed it, although it was originally proposed and patented by Englishman John Barber...
turbine. The core is annular with a centre column as a neutron reflector
Neutron reflector
A neutron reflector is any material that reflects neutrons. This refers to elastic scattering rather than to a specular reflection. The material may be graphite, beryllium, steel, and tungsten carbide, or other materials...
.
PBMR (Pty) Ltd
Since its establishment in 1999, Pebble Bed Modular Reactor (Pty) Ltd grew into one of the largest nuclear reactor design teams in the world. In addition to the core team of some seven hundred people at the PBMR head-office in Centurion near Pretoria, more than a thousand people at universities, private companies and research institutes are involved with the project.In 2009 PBMR (Pty) announced that it was looking at employing the technology for process heat applications , and some pebble bed reactor contracts had been put on hold to prevent unnecessary spending
In early 2010 the South Africa government announced it had stopped funding the development of the pebble bed modular reactor, and PBMR (Pty) stated it was considering 75% cuts in staff. The decision was taken because no customer or investor for PBMR was found. Unresolved technical items, a substantial increase of costs and a 2008 report from Forschungszentrum Jülich about major problems in operation of the German pebble bed reactor AVR had discouraged potential investors. International banks refused to support the PBMR project by loans. PBMRs CEO resigned on March, 8th 2010. In future, the South African nuclear program
South African nuclear program
As a member of the nuclear non-proliferation treaty, South Africa uses nuclear science for peaceful means. The South African nuclear program includes both nuclear energy and nuclear medicine...
will concentrate on conventional light water reactors.
On 25 May 2010 the company announced to staff that it intends to implement a "Care and Maintenance" Strategy. This involves the reduction of staff to 9. The stated purpose of the proposed structure is; preserve PBMR as a legal entity, preserve and optimize IP, preserve HTR license, preserve assets and solicit new investors. The strategy assumes that keeping on 9 employees in the medium term will leave sufficient funding to take PBMR to March 2013. The remaining employees will serve to end of October 2010. Some funding is foreseen for dismantling of the PBMR fuel fabrication laboratories in 2011.
In 2006, the US Department of Energy awarded the PBMR consortium the primary contract for the first phase of its New Generation Nuclear Plant (NGNP) project. The scope for the first phase of this contract, which has now been completed, was for the pre-conceptual engineering of a nuclear co-generation plant for the production of electricity and hydrogen. Requests for proposals for the second phase of the NGNP project will soon be issued, to which the PBMR consortium will be responding within the next few months of 2009. In May 2010 Westinghouse went out of the PBMR consortium, which led to an end of the South African engagement in NGNP.
External links
- PBMR (Pty) Ltd
- Special report published by Pebble Bed Modular Reactor (Pty) Ltd of South Africa on the High Temperature Reactor Conference (HTR) that was held from 28 September to 1 October 2008 in Washington D.C.
- Proceedings HTR 2004
- Abstract of PBMR design for the future, describing PBMR development 1994-2002.