Keeping watch on radiation

Published : Apr 23, 2004 00:00 IST

At the Environmental Survey Laboratory, Dr. M.P Rajan, its officer-in-charge. -

At the Environmental Survey Laboratory, Dr. M.P Rajan, its officer-in-charge. -

THE Environmental Survey Laboratory (ESL) of the Kudankulam Nuclear Power Project (KKNPP) is located in a swank building at the Anu-Vijay township. It houses several facilities with an array of sophisticated equipment. In one of the facilities is a container with ash. Said Dr. M.P. Rajan, officer-in-charge: "It is the ash that we got by burning vegetables. We also reduce milk, fish, eggs, meat and plantain leaves to ash and check them for radioactivity content."

The ESL, which has the task of measuring the radiation levels over a radius of 30 km from the plant, began work in January 2003 when the construction of the plant got under way.

The primary aim of an ESL is to demonstrate compliance with the radiation exposure limits. This requires detailed measurement of the radioactivity content in the air and in vegetables, water, soil, fish, paddy, meat, goat's thyroid and so on. The DAE has set up an ESL at every nuclear facility in the country - Tarapur, Rawatbhatta, Kalpakkam, Narora, Kakrapar and Kaiga, the Nuclear Fuel Complex in Hyderabad, the Indian Rare Earth's plant at Udyogamandal near Aluva in Kerala, and the uranium milling complex at Jaduguda in Bihar. The ESLs report directly to the Health Physics Division of the Bhabha Atomic Research Centre (BARC) and are independent of the operating nuclear facility.

Radioactivity releases contributed by humans are regulated by a set of criteria formulated by the International Commission on Radiological Protection (ICRP) and endorsed by the Atomic Energy Regulatory Board (AERB), which is the watchdog body on safety in nuclear facilities in India. The ICRP has stipulated a limit of one millisievert a year for a member of the public and the AERB has endorsed this. The AERB has stipulated that a nuclear facility worker in the country may receive up to 100 millisievert of radiation over a five-year period, with an average of 20 millisievert a year, but the dose should not exceed 30 millisievert in a given year. The ICRP has stipulated the same five-year dosage but has allowed an annual dose limit of up to 50 millisievert.

Explaining how an ESL worked, Rajan said: "We start collecting samples of air, water, vegetables, milk, fish, goat's thyroid, etc., in a 30-km radius of the nuclear plant several years before it becomes operational and analyse them for radioactivity content. We have been collecting the baseline data around the Kudankulam project site in a 30-km radius since January 2003. This gives us the background level of natural radiation and the fallout radioactivity. We shall compare this data with the data collected after the units go critical. We shall, therefore, know whether there is any increase in the man-made radiation level."

The collection and analyses of samples for their radioactivity content would take place as long as the nuclear facility remained operational. The staff of the ESL at Kudankulam collect samples of air, vegetables, sea water, river water, fish, goat's thyroid, milk, meat and so on every month and of paddy/rice during the harvest season.

The ESL at Kudankulam has detectors for all the three types of radiation - Alpha, Gamma and Beta. "We have sensitive detectors to detect very, very low levels of radioactivity," said Rajan. It has a liquid scintillation analyser to detect tritium and carbon-14 and it can analyse about 400 samples at a time. In the gamma spectrometry analyser, any sample can be analysed for radioactivity. "You will immediately get the result," said Rajan. There is a facility for analysing water samples too.

He pointed to an interesting phenomenon in the area. "Since this area (Kudankulam) is close to Manavalakurichi, we found that certain pockets on the beach had radioactivity by an order of magnitude," said Rajan. The beach sands of Manavalakurichi, from which radioactive thorium is extracted, had monazite. In the inland areas, the radioactivity varied from 0.1 to 0.5 microsievert an hour. But in certain areas of the beach at Kudankulam, the ESL staff found that it was one to three microsieverts an hour. "This is because of the monazite present in the sand. We also found this phenomenon in small pockets on the beach at Kalpakkam (where a nuclear power station is located) and radioactivity was almost of the same level," Rajan said.

Incidentally, the ESL at Kalpakkam had found after the nuclear accident at Chernobyl in April 1986 that the thyroid in goats had registered an increase in iodine-131 as a result of feeding on grass laced with iodine.

THE Anu-Vijay township is a virtual city and is located about 7 km from the plant on the beachhead. Inaugurated on May 27, 2002, by V.K. Chaturvedi, former Chairman and Managing Director of NPCIL, the township has a desalination plant that uses the reverse osmosis method to make seawater potable. Two concrete piplelines laid on the seabed transport sea water to the plant. Doshi Ion Exchange and Chemical Industries, Ahmedabad, erected the desalination plant, said Shirish Palsule, its assistant manager. It has two units that produce 50,000 litres of potable water in an hour, and two more units of like capacity were commissioned on March 12.

The township has 500 quarters and 500 more are to be built. It has a school, a football ground, a cricket pitch, basketball and volleyball courts (all situated on the edge of the beach), a badminton court, a club with a swimming pool, a full-fledged gymnasium, two table tennis boards, a billiards club, a separate club and gymnasium for women, and a club and swimming pool for the Russians helping the building of the project. Putan Singh Tomar, Deputy Manager (Personnel and Industrial Relations), KKNPP, said: "Our township has all the facilities of a city but nothing of its nuisance."

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