In the shadow of Chernobyl

Monday, November 19, 2012
Chernobyl, Kyyivs’ka Oblast’, Ukraine

On 26 April 1986, failures during an experiment being conducted at the Chernobyl Nuclear Power Station in the then USSR led to a massive reactor power increase and the worst nuclear accident in history. The explosion resulted in a radioactive plume spreading over large parts of northern Europe. Hundreds of thousands of people were resettled from nearby areas contaminated with radiation fallout in Ukraine, Belarus and Russia. An Exclusion Zone, a highly contaminated area within a 30-mile radius of the exploded reactor, was evacuated and sealed off in the aftermath of the explosion. Today, about 2,500 employees maintain the remains of the now-closed nuclear plant, working in shifts to minimise their exposure to radiation. Several hundred evacuees have returned to their villages in the area despite a government ban.

A few firms now offer tours to the Chernobyl Exclusion Zone, originally for scientists and researchers only, but beginning to be opened up for mass tourism. As an ex-Nuclear Safety engineer, this would be the highlight of my trip to Eastern Europe. There was also added poignancy as I lived in a small town which is the largest town near to the nuclear power station where I worked.

So, what happened to cause the accident itself? I've tried to keep the following description brief and simple. A test was being conducted by operators to determine the capability of cooling pumps to work after the reactor had shut down and electrical supplies had been lost, since it was known there was a safety deficiency in the plant design, ie. a gap between loss of electrical supplies to the pumps and diesel generators reaching full speed to make up supplies to the pumps. The reactor was supposed to be operating at a certain minimum power level during the test. However, due to reactor dynamics as the power was reduced to this level (reactor poisoning) and an inexplicable decision to insert control rods to further reduce power, the reactor power reduced to a near-shutdown state. Operators proceeded to raise control rods to increase reactor power. Various safety alarms went off as this occurred but were ignored and one of the safety systems was shut off. The reactor was in an extremely unstable configuration. A massive power spike was occurring and insertion of the control rods was insufficient to control it. This resulted in a massive increase in fuel temperature and steam pressure leading to a reactor explosion. The 2000-tonne cap was blown off the top of the reactor, sending a plume of highly radioactive steam and nuclear fuel debris into the atmosphere.

The first firemen on the scene tried to keep the resultant fire spreading to adjacent buildings. Unaware the reactor had been breached, many received massive radiation doses and died in the following days from appalling injuries. Workers (called "liquidators") then shovelled much of radioactive debris from the rooftops of the surrounding buildings back into the reactor. Even wearing heavy protective gear, they could only spend a maximum of 40 seconds at a time working because of the extremely high radiation levels. The reactor itself was covered with bags of sand, lead and boric acid dropped from helicopters. There was still a danger that rainwater could enter the reactor and trigger another chain-reaction and explosion. A large concrete sarcophagus was constructed to seal off the reactor, one of the largest civil engineering tasks in history, involving a quarter of a million workers who all reached their official lifetime limits of radiation. During the construction of the sarcophagus, a scientific team discovered with the help of a remote camera a highly radioactive mass weighing hundreds of tons had melted through the bottom of the reactor into the basement. The mass was composed of sand, glass and a large amount of nuclear fuel and it was named the "elephant's foot" for its wrinkled appearance.

The nearby town of Pripyat primarily housed plant workers and their families. The Soviets did not admit that anything had happened until two days after the accident. The residents of Pripyat went about their business oblivious to what had happened. However, within a few hours of the explosion, dozens of people fell ill. Later, they reported severe headaches and metallic tastes in their mouths, along with uncontrollable fits of coughing and vomiting. Shockingly, it was only after radiation levels set off alarms at a nuclear power plant in Sweden, over 1,000km away, that the Soviet Union admitted that an accident had occurred. Pripyat was evacuated over a period of a few hours only. People were told to bring essential documents, money, etc only as they would soon be returned to their homes. However, they were never allowed back.

The number of deaths resulting from the accident is heavily debated, often depending on the agenda of the party making the estimates, varying from about a hundred killed due to the immediate after-effects of the explosion and a few thousand excess cancer deaths in the future, to more wilder estimates of 100,000s of extra cancer deaths.

It was about a two hour drive to the Exclusion Zone. The local guide mumbled some safety information which no-one could hear. People paid as little attention as they do during an airplane emergency procedure demonstration and we signed our lives away on an indemnity form. To get us in the mood, a video was played on the coach about the disaster, focusing on the radiation effects on the personnel trying to control the disaster and the local population. At the boundary of the Exclusion Zone was the first of two military checkpoints. We got off the coach and filed through, showing our passports and getting ticked off a list before being allowed to pass. Unfortunately, for some reason Gareth was not on the magic list and wasn't allowed to pass. He'd have to go back to Kiev. Or maybe he'd engineered the whole thing because he'd gone two hours without a drink and was getting thirsty.

As we drove through the Zone itself, we passed by mounds in the surrounding countryside. Many villages had been so contaminated that the houses had been demolished and covered with earth. We stopped at a isolated kindergarten. Although now derelict, relics of life stopped in time littered the place. Dolls, books, toys, beds, desks.

The first bit of excitement was in the Zone when we first got a glimpse of one of the massive, iconic cooling towers of Reactor 4 poking above the forest canopy. An unsettling experience and for me, akin to the first glimpse of Macchu Picchu after 3 hard days of trekking on the Inca Trail last year, although the emotions on seeing each would be at opposite ends of the scale. More dread than excitement this time.

One of the main highlights of the trip was the visit to the town of Pripyat. After being evacuated in the space of a few hours, it was now an abandoned ghost town, a snapshot of the one of the darkest moments of Soviet history. It had been looted and reclaimed by nature, with trees, shrubs, weeds and moss bursting through the concrete jungle. I was extremely disappointed that we weren't now allowed to enter the buildings due to safety concerns. Many were crumbling and looked close to collapse. Although now largely looted, looking through blogs of previous visits, you could imagine the snapshot of life on that fateful day when the place was evacuated. School desks, trolleys in the supermarket, books open at where they were last read, toys and personal possessions scattered, photo frames showing memories of lives past. During some visits, you could also enter flats and individual apartments, although out of respect for those who had to abandon their homes and belongings, this was discouraged. The amusement park presented one of the iconic images of the town, with the huge ferris wheel and dodgems overcome with rust and weeds. As we wandered around the town, the guide held up pictures of Pripyat before the accident. Picturesque buildings, streets, and the plaza were now all just scrub, a real-life concrete jungle. Outside, one thing I noticed was the complete absence of birds, and in fact, any wildlife. Look around you wherever you are in the world, whatever time of day, whatever season, and there are birds. Not in Pripyat. Apparently, the area was now a wildlife preserve much visited by naturalists but there wasn't a squeak of anything for our visit.

The guide had a Geiger counter measuring gamma radiation in µsV/h. Now, the effects of radiation depend on the type of radiation (there's plenty of radiation around all the time - natural background radiation, cosmic rays, X-rays, solar radiation), how long you are exposed for, what part of the body is exposed. Of course, most people don't understand this, so for the layman (ie. most of the coach), the important part of the radiation detector is the warning beep. The beep is where it's at. Although generally around a low few µsV/h, there was one inexplicable hotspot in the amusement park on the ashpalt at ~100 µsV/h!

Next it was onto the Chernobyl Nuclear Power Plant proper, a set of six nuclear reactors. The major accident happened on Reactor 4. Even I was amazed at how close we could stand from the Reactor. Maybe 50m and only a low reading of ~ 5 µsV/h. The sarcophagus erected over the reactor was riddled with cracks. Radiation leaked out and rainwater in, creating a radioactive tea inside the building. One side seemed to be being supported by scaffolding. It looked like it could fall in at a moment's notice, leading to a potential nuclear explosion which could irradiate the whole of Western Europe. You can search for Youtube videos for close-ups of the sarcophagus and the interior mess. A new concrete shield is being built alongside the Reactor, financed by the EU, but is behind schedule and it's completion is potentially a race against time. Strangely, we weren't allowed to take photos of it. Remote-operated cranes on the inside would in theory dismantle the existing sarcophagus. There's a video of it in operation here: http://www.youtube.com/watch?v=jvEDVuGOJ6Y

It had been a very sobering day, in more ways than one. A truly fascinating and unforgettable opportunity to visit one of the darkest places on the planet. After exiting through a whole-body radiation monitor, fortunately the only things I would be taking away from my visit would be memories.

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