South Koreans Rush to Buy Salt Before Japan Dumps Nuclear Waste In Sea

South Koreans Rush to Buy Salt Before Japan Dumps Nuclear Waste In Sea

Subject : Science and tech

Section: Nuclear technology

Concept :

• South Korean shoppers are snapping up sea salt and other items as worry grows about their safety with Japan due to dump more than 1 million metric tons of treated radioactive water from a wrecked nuclear power plant into the sea.
• The water was mainly used to cool damaged reactors at the Fukushima power plant north of Tokyo, after it was hit by an earthquake and tsunami in 2011.
• The release of the water from huge storage tanks into the Pacific is expected soon though no date has been set.
• Japan has given repeated assurances that the water is safe, saying it has been filtered to remove most isotopes though it does contain traces of tritium, an isotope of hydrogen hard to separate from water.

Nuclear Waste Disposal

• All radioactive waste facilities are designed with numerous layers of protection to make sure that people remain protected for as long as it takes for radioactivity to reduce to background levels.

Types of nuclear waste and their disposal

• Exempt waste4 (EW): Waste that meets the criteria for clearance, exemption or exclusion from regulatory control for radiation protection purposes.
• Very short-lived waste (VSLW): Waste that can be stored for decay over a limited period of up to a few years and subsequently cleared from regulatory control according to arrangements approved by the regulatory body, for uncontrolled disposal, use or discharge. This class includes waste containing primarily radionuclides with very short half-lives often used for research and medical purposes.
• Very low-level waste (VLLW): Waste that does not necessarily meet the criteria of EW, but that does not need a high level of containment and isolation and, therefore, is suitable for disposal in near surface landfill type facilities with limited regulatory control. Such landfill type facilities may also contain other hazardous waste. Typical waste in this class includes soil and rubble with low levels of activity concentration. Concentrations of longer-lived radionuclides in VLLW are generally very limited.
• Low level waste (LLW): Waste that is above clearance levels, but with limited amounts of long lived radionuclides. Such waste requires robust isolation and containment for periods of up to a few hundred years and is suitable for disposal in engineered near surface facilities. This class covers a very broad range of waste. LLW may include short lived radionuclides at higher levels of activity concentration, and also long lived radionuclides, but only at relatively low levels of activity concentration.Low-level waste is made up of lightly-contaminated items like tools and work clothing from power plant operation and makes up the bulk of radioactive wastes. It represent 90% of the total volume of radioactive wastes, but contain only 1% of the radioactivity.
• Intermediate level waste (ILW): Waste that, because of its content, particularly of long lived radionuclides, requires a greater degree of containment and isolation than that provided by near surface disposal. However, ILW needs no provision, or only limited provision, for heat dissipation during its storage and disposal. ILW may contain long lived radionuclides, in particular, alpha emitting radionuclides that will not decay to a level of activity concentration acceptable for near surface disposal during the time for which institutional controls can be relied upon. Therefore, waste in this class requires disposal at greater depths, of the order of tens of metres to a few hundred metresIntermediate-level wastes might include used filters, steel components from within the reactor and some effluents from reprocessing.
• High level waste (HLW): Waste with levels of activity concentration high enough to generate significant quantities of heat by the radioactive decay process or waste with large amounts of long lived radionuclides that need to be considered in the design of a disposal facility for such waste. Disposal in deep, stable geological formations usually several hundred metres or more below the surface is the generally recognized option for disposal of HLWHigh-level wastes from nuclear generation, but they contain 95% of the radioactivity arising from nuclear power.
• The regular monitoring is done as per the requirements which are in line with the guidelines of International Atomic Energy Agency (IAEA).
• The monitoring of various environmental matrices such as air, water, soil etc., in and around the waste disposal facilities is carried out by independent Environmental Survey Laboratories (ESL) of Bhabha Atomic Research Centre (BARC) which are stationed at all the nuclear sites.