Radioactivity is invisible, has no smell, makes no sound?in fact it cannot be detected by any of our senses. Yet, in case of a radioactive spill arising out of a nuclear accident, harmful effects to human mankind can be unimaginable.
The recent contamination of a water cooler in Kaiga nuclear power plant in Karnataka has once again raised question marks on security procedures at nuclear plants. Was it an act of mischief, any violation of operating procedures, leak or security breach? While a thorough investigation is underway, there is an equivocal call to put in place a proper mechanism to ensure that such accidents do not happen again. There is also a strong demand to equip the investigators with advanced tools to detect radiation if there is nuclear fallout.
These days, nuclear technology is used in several applications. Some of these include medicinal, power generation and of course military. Out of these, nuclear energy based power is getting popular. In general, nuclear installations are highly sophisticated, and, have lots of control measures in place to prevent any major hazard.
However, the fact is that in spite of all these sophistications, accidents still occur. The problem with nuclear accidents is though, less frequent due to high degree of sophistication and control measures, but, once an accident occurs, the impact is severe.
Defence experts recall some of the worst known nuclear accidents such as the Three Mile Island, near H Harrisburg Pennsylvania, US in 1979 and the Chernobyl disaster in Ukraine in 1986. In addition, once in a while, smaller incidents of minor amounts of leaks get reported from around the world. For instance, there was a radioactive spill of 40 litres of liquid containing plutonium in the reprocessing plant in Rokkasho-Mura in Japan three year back. In August 2004, a pipe was ruptured in the Mihama nuclear power plant in Japan, which resulted in the death of five workers. A Greenpeace report estimates that 2,70,000 cancers and 93,000 fatal cancers were caused by that disaster.
Analysts inform that when a nuclear warhead detonates at altitudes between 25 and 250 miles, it emits a high-altitude electromagnetic pulse, or EMP, which disrupts and damages electronic systems, including electric grids. Geomagnetic storms that occur from significant changes in solar wind pressure can have a similar impact.
In 1962, a US nuclear test at an altitude of about 250 miles above Johnston Island in the Pacific Ocean caused street lighting systems to fail, tripped circuit breakers, triggered burglar alarms and damaged a telecommunications relay facility in the Hawaiian Islands nearly 900 miles away.
Closer home, whatever happened at the water cooler in the Kaiga atomic plant with radioactive tritium last month is still being investigated. It will be some time before we know whether the Kaiga incident was the handiwork of a prankster or a ?malevolent? act as described by the minister of science and technology Prithviraj Chavan. However, Nataraja Sarma, a retired nuclear physicist says it could be just a human error?not uncommon at the Bhabha Atomic Research Centre (BARC). Preliminary probe into the radiation contamination has shown it was possibly an act of mischief and does not reveal any violation of operating procedures. A similar incident happened in 1990 at the Point Lepreau Nuclear Generating Station in Canada.
However, because radioactivity affects the atoms that it passes, we can easily monitor it using a variety of methods: Geiger-Muller tube, photographic film, gold leaf electroscope, spark counter, cloud chamber, bubble chamber and modern detectors.
Typically, tritium is the radioactive isotope of hydrogen, but the beta radiation emitted by it is of such low energy it cannot even penetrate the human skin. In other words, tritium can cause harm only if it enters the body through food or water, but its intake must be in large amounts to pose a significant health risk.
Some tritium is naturally formed in the upper atmosphere by cosmic rays. The air also contains tritium left behind by atmospheric weapons testing between 1954 and 1962. But most tritium in the environment today is discharged from Kaiga-type reactors that use heavy water as moderator and coolant.
Then, heavy water is chemically the same as regular (light) water, but with the two hydrogen atoms replaced with atoms of deuterium?another isotope of hydrogen. Irrespective of how tritium entered the Kaiga water cooler, the incident highlights the need for vigilance in nuclear plants, opine experts. ?At present, our plants are guarded by the Central Industrial Security Force (CISF),? says the Navy chief Nirmal Verma.
Noting that the sensitive plant was safe and secure from intrusion or outside threat, Kaiga director JP Gupta says that the unit had fool-proof security and stringent procedures are followed to screen the employees and contract workers when they enter during their working hours and when they leave the premises.
Very high radiation doses can destroy body functions and lead to death within 60 days, but such ?noticeable? deaths would be expected in only 2% of reactor meltdown accidents; there would be over 100 in 0.2% of meltdowns, and 3,500 in 1 out of 1,00,000 meltdowns. The radioactive waste products from the nuclear industry must be isolated from contact with people for very long time periods. The bulk of the radioactivity is contained in the spent fuel, which is quite small in volume and therefore easily handled with great care.
The effects of routine releases of radioactivity from nuclear plants depend somewhat on how the spent fuel is handled. A typical estimate is that they may reduce our life expectancy by 15 minutes. We could surely do with fast-tracking detectors at nuclear plants and other installations.