Koodankulam Nuclear Plant : Risk Analysis on Spent Fuel – Part 4

(An engineer by profession, Sasikumar holds double masters degree in Engineering from India and Business Administration from USA.)

Please also read Part 1 , Part 2  and Part 3 of this article.

Nuclear power plant uses nuclear fission techniques in which atom splits into smaller parts and release the abundant quantity of heat energy. The most commonly used nuclear fuel is Uranium and in some cases Plutonium or Thorium. Uranium is available from the ground in some parts of the world. It is further processed into small pellets and loaded in the long rods and used in the nuclear power plant as a fuel. The nuclear chain reaction releases lot of radioactive materials which are harmful to humans and should keep in the protected enclosed environment.

Spent nuclear fuel is nothing but used fuel of the nuclear power plant and it no longer holds the ability to sustain a nuclear chain reaction. Spent fuel  removed from the nuclear reactor is stored typically in the spent fuel pool in the nuclear power plant. Spent fuels are located either within the containment or in many cases located outside the containment. In Fukushima nuclear disaster, spent fuel of last 20+ years have been kept in the spent fuel pool and stored within the containment. There were some reports that claims spent fuel pool has been in fire due to lack of cooling water and emitted substantial quantity of radioactive steam to the atmosphere. It is not clear where these spent fuels of Koodunkulam power plant will be stored since over the years, this repository will pose a huge challenge to keep it safe and maintain properly to avoid spreading of radioactive contaminants to the atmosphere.

Approximately Spent Nuclear Fuel of U-233 will have a half-life of 159,200 years. A typical nuclear plant can have hundreds of active fuel rod bundles in each core; thousands of spent nuclear fuel rods in the water tanks and thousands of spent nuclear fuel rods in dry drum storage. Water in the tanks acts as a coolant, moderator and radiation shield as long as the water level around the nuclear rods in the tank is maintained well. In the event of spent nuclear fuel rods  exposed and un-cooled,  there will be a swift oxidation and tremendous heat stress can ultimately compromise the cladding. This will result uranium being exposed and produce hydrogen and release fission byproducts to atmosphere. The un-cooled spent nuclear fuel rods can create ample radiation and heat that will pose severe health hazard to humans and other living animals.

In the United States there was a proposal to keep all the spent fuels of several nuclear plants in the Yucca Mountain underground repository, Near Los Vegas, Nevada. In that process all the spent fuels will be shielded, packaged and stored several mile beneath the underground tunnel in order to prevent the migration of radioactive substance from the reaching mankind’s for thousands of years. Several million tax payers’ dollars have been spent to develop the repository. However due to numerous protest from the public of Yucca Mountain region this project has been currently put on hold. On March, 2009, US Energy Secretary Steven Chu informed the Senate hearing that “The Yucca Mountain site no longer was viewed as an option for storing reactor waste”.

Whenever nuclear reactor has been shutdown and nuclear chain reaction has been stopped successfully yet large quantity of heat will be dissipated from the fuel rods due to decay of fission products. The moment the reactor is shutdown the decay heat will be 7 to 8% of the last core power and after one hour it will be around 1.5 to 1.7% of core power. After one day decay heat will be reduced to 0.4 to 0.5% and after one week it will be about 0.2 to 0.3% of core power. The decay heat release will continue to slowly decrease over a long period of time. Considering the 1000+MW of Koodunkulam power plant huge quantity of water will be required to cool the plant for several days even after shutdown.

As per US NRC Regulations Title 10, Code of Federal Regulations, Part 21- Reporting of defects and noncompliance; it is mandatory to report to the Government for any short fall in the design, construction or operation of the nuclear power plant. Failure to provide such information may lead to the civil and criminal penalty equal to the amount provided by section 234 of the Atomic Energy Act of 1954, as amended.  

The primary purpose of the above act is to eliminate and avoid the catastrophe since nuclear accidents will bring damage to the civilization and land for hundreds and thousands of years. Hence those who are bringing the safety concern in Tamil Nadu and Kerala are merely performing their citizen duty. Question their integrity in the name of religion, caste, linguistic or other reasons will not fit well to the democratic freedom of India.

Engineers are learning a great deal from the failures. The Fukushima accident was an eye opener to the world nuclear industry in general and Koodankulam nuclear plant in particular. The purpose of commissioning the nuclear power plant is to provide electricity to the citizens. If the same Indian citizen’s life and land will be compromised to the tune of even less than 1% chance it is wise to find an alternative solution rather than enforcing the unsafe environment on them. It is not rare to stop the near completed nuclear power plant by citing safety reason. After Chernobyl disaster in USSR, Philippines have stopped commissioning of nuclear power plant due to safety reason and have converted the nuclear power plant to a tourist attraction. The attached image shows Philippines earlier nuclear plant cum then converted tourist spot.

Those who are supporting the plant and opposing the plant are sharing each side of coin of democracy. Both of them are deserve to hold India’s highest honor since they are fighting for betterment of the country. No one is loser here, India will be the clear winner by scrapping the Koodankulam nuclear plant since Southern Kerala and Tamil Nadu  will be safe from the threat of nuclear contaminants for next several thousands years.




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