Context:
The Japanese government says treated and diluted radioactive wastewater from the Fukushima Daiichi nuclear power plant will be released into the ocean as early as August 24.
About the news
The water is discharged after treatment through a filtration process known as Advanced Liquid Processing System (ALPS) to remove most of the radioactivity before being stored.
Advanced Liquid Processing System (ALPS) is a pumping and filtration system, which uses a series of chemical reactions to remove 62 radionuclides from contaminated water. However, ALPS is not able to remove tritium from the contaminated water.
About Fukushima Daiichi Nuclear Power Station
- Location – Japan
- The plant consists of 6 light water reactors – all are boiling water reactors
The light-water reactor (LWR) is a type of thermal-neutron reactor that uses normal water, as opposed to heavy water, as both its coolant and neutron moderator. There are 3 varieties of light-water reactors: pressurized water reactor (PWR), boiling water reactor (BWR) and supercritical water reactor (SCWR).
Fukushima accident
- In 2011, Japan was shaken by what became known as the Great East Japan (Tohoku) Earthquake. It was followed by a tsunami.
- This was followed by an accident at the Fukushima Daiichi Nuclear Power Station, which was ultimately categorized as a Level 7 — Major Accident — on the International Nuclear and Radiological Event Scale.
- The chain of events caused radiation leaks and permanently damaged several of its reactors, making them impossible to restart.
- The working reactors were not restarted after the events.
- 2nd worst nuclear accident in the history of nuclear power generation – the worst being Chernobyl disaster (1986)
Location of Chernobyl Nuclear Power Plant – Pripyat (Now Ukrain – then Soviet Union)
International Nuclear and Radiological Event Scale (INES)
- INES is a tool for communicating the safety significance of nuclear and radiological events to the public.
- Developed in 1990 by the IAEA and the Nuclear Energy Agency of the Organization for Economic Co-operation and Development (OECD/NEA).
- Member States use INES on a voluntary basis to rate and communicate events that occur within their territory.
- It is not a notification or reporting system to be used in emergency response.
- Initially the scale was applied to classify events at nuclear power plants, then extended and adapted to enable it to be applied to all installations associated with the civil nuclear industry. Subsequently been extended to all events associated with the use, storage and transport of radioactive material and radiation sources.
- Events are rated at 7 levels. The scale is logarithmic – that is, the severity of an event is about ten times greater for each increase in level of the scale.
Source: The Hindu
Previous year question
In India, why are some nuclear reactors kept under “IAEA safeguards” while others are not?
[UPSC Civil Services Exam – 2020 Prelims]
(a) Some use uranium and others use thorium
(b) Some use imported uranium and others use domestic supplies
(c) Some are operated by foreign enterprises and others are operated by domestic enterprises
(d) Some are State-owned and others are privately-owned
Answer: (b)
