19 October 2010

What is SPENT FUEL???


          As we all discuss in previouse all are the benefits and the operational of the nuclear reactors, today I would like to share about the nuclear waste or also known as “spent fuel”. To be more specific  it is the nuclear fuel  which had been irradiated in the nuclear power plant.
         For information, long-lived radioactive waste from the back end of the fuel cycle, the actinides have a significant influence due to their characteristically long half-lives. Depending on what a nuclear reactor is fueled with, the actinide composition will be different. For example, nuclear fuels with thorium(Th-232) this fertile material that can undergo a neutron capture reaction and two beta minus decays, resulting in the production of fissile U-233. The spent fuel cycle with thorium will contain U-233, an isotope with a half-life of 160,000 years.  While, the burnt fuels are Thorium with Reactor-Grade Plutonium (RGPu), Thorium with Weapons-Grade Plutonium (WGPu) and Mixed Oxide fuel (MOX). For RGPu and WGPu, the initial amount of U-233 and its decay around millions of years.

           However, the amount of the radioactive wastes are very small compared to the wastes generated from the fossil fuel electricity generation. When we talk about the waste, everyone worried about what can we do on it. Before going to the disposal process,
Interim storage of spent fuels at the reactor site are needed in order to decrease their heat and radioactivity.There are two type of storage which is wet and dry storage(to be explained in next post). Interim storage, designed to last for perhaps 30-50 years (though with flexibility to shorten that time to match the progress of permanent solutions) should be pursued as the best near-term approach to managing a large fraction of the world’s spent fuel, including much of the spent fuel in the United States and Japan.
          Nowadays, there are several ways to treat these waste such as geological disposal and reprocessing. Firstly, we would like to touch on Nuclear reprocessing  which able separate spent fuel into various combinations of reprocessed uranium, plutonium, minor actinides, fission products, remnants of zirconium or steel cladding, activation products, and the reagents or solidifiers introduced in the reprocessing itself. With the reprocessing method,the spent fuel can be reuse in the nuclear reactor once again hence, the volume of the waste can be greatly reduced.
           Alternatively, the Spent Nuclear Fuel  can be disposed of as radioactive waste. United States has planned disposal in deep geological formations, such as the Yucca Mountain nuclear waste repository, where it has to be shielded and packaged to prevent its migration to mankind's immediate environment for thousands of years.The waste would be encased in tough materials and would use the surrounding rock as a barrier to prevent radioactive leakage into the environment.


  1. for the disposal case, as given example The waste would be encased in tough materials and would use the surrounding rock as a barrier to prevent radioactive leakage into the environment. so what will be the results when there was natural disaster happened, like eartquakes and volcanos?? ;mountains that used as waste repository damaged??

    sivabalan s/o sanafhei raja

  2. siva:

    These issue has been carried out since decades ago.Many research and development had been done to over come this issue.

    Mountains been used as waste repository is not the only way to manage these waste. For example, the formation that makes up Yucca Mountain was created by several large eruptions from a caldera volcano and is composed of alternating layers of ignimbrite (welded tuff), non-welded tuff, and semi-welded tuff. The tuff surround the burial sites is expected to protect human health as it provides a natural barrier to the radiation.

    About the earthquake, before the site been selected as the repositary site studies and research are been carried out regarding the seismic activity.

    When looking for a site for permanent storage of high level waste, engineers and geologists took several factors into consideration, including: water table, geological stability, rock composition, seismic (earthquake) activity, and proximity to population areas.

    Furthermore, the site must have a high probability of remaining undisturbed for tens of thousands of years, or as long as the materials in storage are radioactive.

    Yucca Mountain is located in a rural region, with sparse population. Las Vegas, 100 mi (161 km) from the site, is the nearest metropolitan area. Within a 100-mi radius of the proposed site, there are approximately 35,000 inhabitants. Thus, Yucca Mountain is relatively secluded.