Ch. 15 RG

clean coal technology

DOE's clean coal R&D is focused on developing and demonstrating advanced power generation and carbon capture, utilization and storage technologies for existing facilities and new fossil-fueled power plants by increasing overall system efficiencies and reducing capital costs. In the near-term, advanced technologies that increase the power generation efficiency for new plants and technologies to capture carbon dioxide (CO2) from new and existing industrial and power-producing plants are being developed. In the longer term, the goal is to increase energy plant efficiencies and reduce both the energy and capital costs of CO2 capture and storage from new, advanced coal plants and existing plants. These activities will help allow coal to remain a strategic fuel for the nation while enhancing environmental protection

fluidized bed coal combustion

Fluidized beds suspend solid fuels on upward-blowing jets of air during the combustion process. The result is a turbulent mixing of gas and solids. The tumbling action, much like a bubbling fluid, provides more effective chemical reactions and heat transfer.

Fukushima Japan Nuclear Disaster - 2011

In March, 2011, a tsunami struck and water knocked out cooling systems to three of Fukushima's reactors, which went into a state of partial meltdown. Unit 4 was undergoing maintenance, so all of its fuel rods were being stored. But a build-up of hydrogen triggered an explosion in Unit 4, damaging its structure. Experts say hydrogen explosions after the earthquake and tsunami in March 2011 have made the current storage facility vulnerable to further tremors. Workers at Japan's stricken Fukushima nuclear plant have begun removing fuel rods from a storage pond at the Unit 4 reactor building. The delicate operation is seen as a necessary step in stabilising the site.It will take about two days to remove the first 22 fuel rod assemblies, plant operator Tepco says.Overall, more than 1,500 assemblies must be removed in what correspondents describe as a risky and dangerous operation set to take a year.

Chernobyl Nuclear Disaster - 1986

The Chernobyl accident in 1986 was the result of a flawed reactor design that was operated with inadequately trained personnel. The resulting steam explosion and fires released at least 5% of the radioactive reactor core into the atmosphere and downwind - some 5200 PBq (I-131 eq). Two Chernobyl plant workers died on the night of the accident, and a further 28 people died within a few weeks as a result of acute radiation poisoning. UNSCEAR says that apart from increased thyroid cancers, "there is no evidence of a major public health impact attributable to radiation exposure 20 years after the accident." Resettlement of areas from which people were relocated is ongoing. In 2011 Chernobyl was officially declared a tourist attraction. The April 1986 disaster at the Chernobyla nuclear power plant in Ukraine was the product of a flawed Soviet reactor design coupled with serious mistakes made by the plant operatorsb. It was a direct consequence of Cold War isolation and the resulting lack of any safety culture.he Chernobyl disaster was a unique event and the only accident in the history of commercial nuclear power where radiation-related fatalities occurrede. However, the design of the reactor is unique and in that respect the accident is thus of little relevance to the rest of the nuclear industry outside the then Eastern Bloc. However, it led to major changes in safety culture and in industry cooperation, particularly between East and West before the end of the Soviet Union. Former President Gorbachev said that the Chernobyl accident was a more important factor in the fall of the Soviet Union than Perestroika - his program of liberal reform.

Three Mile Island Nuclear Disaster - 1979

•In 1979 at Three Mile Island nuclear power plant in USA a cooling malfunction caused part of the core to melt in the # 2 reactor. The TMI-2 reactor was destroyed. •Some radioactive gas was released a couple of days after the accident, but not enough to cause any dose above background levels to local residents. •There were no injuries or adverse health effects from the Three Mile Island accident. The accident to unit 2 happened at 4 am on 28 March 1979 when the reactor was operating at 97% power. It involved a relatively minor malfunction in the secondary cooling circuit which caused the temperature in the primary coolant to rise. This in turn caused the reactor to shut down automatically. Shut down took about one second. At this point a relief valve failed to close, but instrumentation did not reveal the fact, and so much of the primary coolant drained away that the residual decay heat in the reactor core was not removed. The core suffered severe damage as a result. The operators were unable to diagnose or respond properly to the unplanned automatic shutdown of the reactor. Deficient control room instrumentation and inadequate emergency response training proved to be root causes of the accident.