The recent earthquake and tsunami in Japan has brought Nuclear Safety to the forefront again. In the Fukushima Daiichi plant, three explosions occurred, which have caused alarm that the reactors may release radioactive emissions into the atmosphere. Reactors have a core consisting of fuel rods which, on the nuclear reaction, emit heat. The heat is used to generate steam, which runs a turbine and generates electricity.
In a crisis, reactors automatically shut down. Control rods are inserted between fuel rods to prevent further reactions. But they’re all still very hot and emanating heat. During this time, the reactor needs to be continuously cooled — and that is done by using water, draining out the steam, putting fresh water, etc. This process needs some power, which wasn’t there with Japan’s electricity gone due to the Tsunami reaction, and the limited capacity of backup generators. The process is now being carried out by supplying water from the ocean, even that is steaming up so fast that water levels are dangerously low.
Three explosions have since occurred at the plant, attributed to hydrogen reacting with air; hydrogen is produced when the fuel rod cladding reacts with water. That is not a bad sign if there is no breach of the primary containment vessel inside which the reactor is housed. (The secondary, or external, containment structure is designed to burst on high pressure, to protect the primary or inner shell) Reports are scarce, but we don’t know of any breach in the primary containment structure.
Additionally, steam has to be continually released into the atmosphere to relieve the unit of some pressure. In the early part, this steam was "clean" — radioactive elements were within limits. Now, with the damage, exposure of fuel rods to air and explosions, even steam release is turning out to be dangerious. Helicopters and measurements outside the main zone have detected higher-than-safe levels of radiation. Japanese authorities have requested people living 20 to 30 kilometers away from the plant to stay indoors, close windows and use no air conditioning.
The danger now is of a complete meltdown and a breach of the containment vessels. The Japanese government has admitted this is a possibility and evacuations around the plants are on.
This is the worst nuclear disaster after Chernobyl in Russia (1986), and the Three Mile Island partial meltdown in the US (1979). The US has seen no new plant come online after the Three Mile Island incident. Nuclear power is very big in Japan — nearly 1/4th of their energy is nuclear, so it’s not going to be easy to replace; yet, there have to be solutions.
So was this a disaster a failure of nuclear power? Most other reactors in Japan seem to be coping well — even the Indian plant in Kalpakkam survived the tsunami in 2004 through an automatic shutdown and a restart days later.
The Nuclear Power Corporation of India Limited (NPCIL) has released a presentation with some interesting details:
• The plant shut down as expected, on recognizing the quake. Diesel generators came on to run the cooling system.
• The tsunami carried away the DG fuel oil tanks.
• The valve control equipment and switchgear was damaged by the tsunami.
• Now there was no power, no back up (diesel fuel tanks were gone) and no control system to feed emergency water or coolant.
• That built up pressure inside the reactor — which should usually be let out. But, to avoid releasing the radioactive vapours for as long as possible, the pressure built up to twice what the structure was designed for.
There are lessons to be learnt in here — especially in emergency backup situations. In a place wrecked by earthquakes and tsunamis, one might want to reconsider building a reactor at sea level, next to the shore; or at least, to keep the water impact to a minimum. And the three reactors produce about 2000 MW of power, and are a small percentage of the overall population (Japan has 54 operational reactors).
But it is not a question of percentages — even one big blow-up can have serious consequences for a large number of people. If there is a meltdown and breach, we can’t even imagine how many lives will be affected. Yet, it may be worthwhile to analyze what happened before writing off nuclear power altogether. India has already started a review of the safety mechanism of its own plants.
In India, there were hopes of the Nuclear Power Corporation of India (NPCIL) going for an IPO and perhaps, getting more transparent in the process. For the near term, it looks like that is out of the question. The Indo-US nuclear deal would have allowed India to get access to reactor technology, but more importantly, to Uranium. There may not be much progress there, especially if the Japanese problem gets worse.
India, has been conducting a lot of useful nuclear research, especially with the use of thorium in reactors. We have the world’s second largest thorium reserves, and thorium can be used to build "breeder" reactors (which produce more fuel than they consume) and lead to self-sufficient power generation. (We have to import uranium for current reactors) Will this event lead to the end of such research?
Even with the Japanese nose for quality and process, a disaster of this magnitude has struck them, and there is little reason to believe India will have fared much better. In a disaster, we react ridiculously — the military team to fight the 26/11 terrorists were stuck for hours in a plane! In that context, any effort to increase our nuclear footprint must be accompanied by trust-building that we have measures to control the radiation fallout and a documented and planned response process. It’s not the nuclear plants themselves; it’s also towns nearby, supply of iodine (to counter radioactive iodine in the atmosphere), local knowledge etc.
Where there was seawater poured into the reactor cores (1,2 and 3 out of the six) are now too impure to work with — the reactors will have to be decommissioned. The shortfall of 2000MW is not much, honestly. With only a few more coming up, the impact to the future within Japan is not huge, unless this event gets worse and due to public pressure, they have to consider shutting down all other plants as well. But the rest of the world, some of which was banking on the highly efficient nuclear system for power generation, might have to rethink, even if technically, current mistakes can be fixed. The power industry will start to look more closely at future at alternatives — so solar, hydro power, wind and natural gas industries should see some added interest.
The future of nuclear power seems to ride on what happens now in Japan. If there is success is curtailing further damage, all of this will be forgotten in a year. If things get worse, and it turns out the plants have had the highest safety procedures, forget about nuclear technology for the next decade. (But that’s a small side-effect — the biggest concern is for the millions of people living nearby.) I expect the debate to get stronger.