Chernobyl: 25 Years Later

By Joe Colvin

Now that the recent events at the nuclear plants at Fukushima are largely behind us and the stabilization is underway, we look to the 25th anniversary of Chernobyl and recognize that comparisons are inevitable.  But it’s vital that we keep these events in perspective as we face the challenges of developing our energy resources for our global future.

As more and more experts around the world consider the best solutions to our continuing need for new clean energy sources, nuclear energy is experiencing a world-wide renaissance.  As President Obama acknowledged in his State of the Union address, nuclear energy is essential in solving our energy problems.  The safety record of nuclear energy in the United States is excellent — in fact, no member of the public has ever been injured or killed in the entire history of commercial nuclear energy in the U.S.

Today, 25 years after the worst nuclear disaster in history occurred at Chernobyl in the Ukraine, we must examine what happened, why it happened, and why it cannot happen here in the U.S.  It’s also important to consider how Fukushima will teach additional lessons about nuclear energy.   Looking back and to the future, it is clear to see that better reactor designs, a strict regulatory process and an industry that embraces safety throughout all aspects of operations are all safeguards in place that create an environment where an accident like Chernobyl is simply not possible.


Chernobyl-4 reactor after the accident (center), its turbine building (lower left), and Chenobyl-3 (center right).

The accident at the Chernobyl 4 nuclear reactor occurred because of a confluence of events resulting in the worst nuclear disaster in history.  The tragedy was a result of a combination of design flaws that made the reactor dangerous to operate and lapses in safety procedures.  The result was an accident which destroyed the reactor in a fatal release of heat, fire and steam in a matter of seconds.

The Chernobyl reactors were a special design using highly enriched uranium in a graphite moderator—and as we learned from studying the event—the accident could only have happened with this type of design.   The reactors were created to produce weapons grade plutonium for the Soviet military forces along with electricity for commercial use.  They were difficult to operate and required constant adjustment to remain stable.  The officer in charge was an electrical engineer who was not a specialist in reactor plants. The sequence of events which caused the accident occurred when operators began an engineering procedure to test the main electrical generator, which was outside of the reactor building.  Delays in starting the test, and management pressure to meet the schedule, resulted in several crucial outcomes that combined to cause the accident.


The Fukushima reactor complex, before March 11, 2011, provided 10% of Japan's nuclear generated electricity.

At Fukushima, from what we know at this time, it’s also plain that situation arose, not from human error in design or operation, but rather from the most extraordinary and unprecedented natural disaster in human memory—and what’s more, it was the tsunami wave, not the earthquake, which occasioned the loss of power and therefore challenged the cooling of the reactors.  In fact, the reactors operated as designed and built – they shut down automatically when the earthquake occurred.

Further, it’s absolutely imperative that we recognize that no one died as a result of the incident and that all the safety steps undertaken were well planned and implemented in a transparent manner to avoid panic.  We also know that while the rating of the Fukushima incident, established by the International Atomic Energy Agency, is at the same level as Chernobyl, the rating includes three reactors in Japan, rather than just one.  More importantly, the radiation releases from Fukushima are just one-tenth compared to Chernobyl.

The designs of plants in the United States are such that a Chernobyl type accident simply could not occur; in addition, all plants in the US have been carefully tested seismically so that we may be assured that the American public is protected against a Fukushima type earthquake and tsunami.  And, even more importantly, because of the culture of safety among nuclear scientists and engineers—and indeed, the entire nuclear community—additional scrutiny, study, and, where necessary, modifications will be undertaken for further protection.  The same safety culture led to a similar process occurring after the tragic events of September 11, 2001, when all plants were analyzed for their ability to withstand a terrorist attack and changes were made.

Nuclear scientists world-wide have joined together in a host of professional organizations with a renewed commitment to the highest levels of safety throughout all aspects of the process, and there’s no question that safety regulations and culture are now worldwide features of the nuclear industry.  Around the world, safety improvements and best practices are continually monitored, enhanced, and then shared among all nuclear utilities through the World Association of Nuclear Operators (WANO). These factors are fundamental guarantees that insure the safe, reliable delivery of electricity from nuclear reactors.

Today worldwide 16% of all electricity generated comes from nuclear reactors, and China, India, and 30 other countries are committed to building dozens of new nuclear power stations as well, which demonstrates the vitality of the nuclear renaissance.  For our part, as we look to the future we need to think not only about our energy needs, but also about the planet Earth we will pass along to future generations.  Will we continue to rely on fossil fuels and force future generations to endure the consequences of a world suffering from the effects of global warming?  Or will we create a future that includes nuclear energy and a world that benefits as a result of the clean and efficient energy it delivers?

Life-Cycle Emissions

Source: "Life-Cycle Assessment of Electricity Generation Systems and Applications for Climate Change Policy Analysis," Paul J. Meier, Univ. of Wisconsin-Madison, Aug. 2002

Almost 50 people died in the Chernobyl disaster.  But even as we mourn those who lost their lives that fateful day 25 years ago, we must also acknowledge the important changes the industry has made around the world that ensure the safety of this energy source.  We also know, even at this early stage, that no one died as a result of the incident at Fukushima, and we’ll continue to study the events there in order to improve safety and reliability.  We honor the memory of those at Chernobyl and the bravery of those who worked to stabilize the Japanese plants, but we also recognize the important role nuclear energy can play in our future.




Joe Colvin is the 56th president of the American Nuclear Society. He has been an ANS member since 2001 and has worked to obtain senior nuclear utility expertise on ANS committees and the Board of Directors. Colvin is President Emeritus of the Nuclear Energy Institute, and he serves on the boards of Cameco Corporation, the world’s largest uranium company, and US Ecology, a hazardous and radioactive waste disposal company. He also is on the boards of non-profit organizations such as the Foundation for Nuclear Studies, which was set up by NEI to help provide the U.S. House and Senate with information on nuclear technology.

11 thoughts on “Chernobyl: 25 Years Later

  1. Bill Eaton

    Fukushima will be the platform for future decisions that will most likley result in revised design standards and emergency preparedness processes/procedures. Until all is known about the event, most importantly the human and organizational performance issues surrounding the event, all should strive to get as much factual information on the table as possible. The above string illustrates the use of incomplete date to support preconceived notions and well established adversarial positions. Political bandwagons are a poor vehicle for resolution of problems.

  2. Brian Mays

    Man, I love that guy. Surprising he hasn’t been shot really.. or poisoned.

    Maybe he doesn’t sleep so good.

    Nice, Luke. There’s nothing like injecting some good old-fashioned paranoia into your comments to assure everyone that you’re not a fringe lunatic.

    As you said, “a little false information goes a long way,” and it appears that you’re trying to get the most out of it. You’ve already got the basics of spreading FUD (Fear, Uncertainty, Doubt) down pat. For example, you refer to “new studies” without citing any references. Just don’t go off the deep end, if you want it to work. ;-)

    Assassination stories don’t tend to play very well.

  3. Luke


    I looked up naive in a dictionary, so now I know what you look like!

    I suppose you are right about the correction – you never said anything about the generators they brought in – you only referred to the submerged generators, which indeed never ran out of fuel. Were you unaware of the fact that the generators they used after the tsunami ran out of fuel?

    What exactly did you want me to quantify? I thought my points were quite clear and I’m certain the people of Fukushima would agree with them. Over the past 6 weeks it has become apparent to me, as a lay person, that most of the problems in the history of nuclear power pertain to an inability to cool the damn things down. I don’t except that engineers in this field are not infinitely more familiar with this concept than me.

    The push I describe is not some clandestine meeting held in a secret base on the moon, the bottom line is the dollar. If nuclear fission is your bread and butter, whether it be as a 9-5 technician at a plant, a retired politician taking an executive position at TEPCO (smelly), a nuclear engineering student or uranium share holder (have a look at Australia’s coverage of the catastrophe) the majority of them will seek out information that justifies their position morally. That’s human nature and we all do it – your business is unique, however, as it provides something that other industries can also provide without the delay in net energy production and at a fraction of the cost and risk. A little false information goes a long way – the repeated comparison of chest xray doses of radiation to radioactive particle exposure springs to mind (by the way, new studies into heart patients who receive radiation from imaging during treatment have shown significant increases in cancers with related mortality at 5 years and that’s without ingestion of particles).

    The Arnie Gundersons are unfortunately the exceptions in this world, I bet he sleeps well at night though.. Man, I love that guy. Surprising he hasn’t been shot really.. or poisoned.

    Maybe he doesn’t sleep so good.

  4. Joffan

    Luke, your “correction” doesn’t correct anything I wrote.

    Your “obvious errors” are unquantified and useless. Nuclear organizations are eager to learn from anything that went wrong – or indeed could have wrong, but luckily didn’t – during this accident. There is no “big push” to ignore or dismiss it as you suggest.

  5. Brucie B

    Reality is no human constructed endeavor is 100% perfection there’s always Risk Assessment spread over time. Unless changes are made to mega projects to mitigate statistical risk pile-up (SLE), (ALE). Trouble is nearer than first thought.
    This was not the first time Pacific Plate decided to stress bounce. Maybe an annualized serious Risk Assessment should have been taken and acted on.
    Risk was more significant than say, a 15 mile wide iron-nickel Meteor (NEO) striking a 300MW underground sodium-cooled fast reactor complex.

  6. Luke

    Correction: the diesel in the diesel generators they brought in, after the back up failed because of water damage, did run out temporarily and it did cause the fuel to heat further.

    There is a big push from those for the industry to explain the disaster as an unforeseen event – if it was foreseeable and they missed or ignored it, what else have they missed? They want to take human error out of the discussion so that their fail safe designs stand up to better scrutiny.

    Glaringly obvious human errors I can see immediately:

    1) The plant was built much too low.
    2) The plant is of a design that requires massive amounts of energy and waterflow to keep it safe if it shuts off.
    3) The back up diesel generators were stored inappropriately.
    4) The spent fuel was stored inappropriately.
    5) The plant was built where a massive tsunami had occurred less than 100 yrs ago.
    6) There were no back up, back up generators.

    Even if we do learn from this (which we won’t – there will be spent fuel above Fukushima style reactors in the states for the foreseeable future), you have missed the point that we as humans are imperfect and this particular lesson will be irrelevant when the next ‘unforeseen’ catastrophe inevitably occurs. This type of event will become more common if expansion of this insanity is entertained.

  7. Luke

    The United Conflicts of Interests.

    That was a typically optimistic appraisal from someone with obvious interests. The plant is still emitting a terabecquerel/hr with no definitive solution in sight and this guy’s ready to wash his hands and go home! Just yesterday a Japanese dude posted a video on you tube of him scurrying around with his geiger counter recording very scary levels of radiation throughout Fukushima prefecture (30-70km from the plant).

    According to the IAEA, unidentified ‘white smoke’ is still spewing from reactors 2, 3 and 4, six weeks after the initial insult and on the back of a recent report from TEPCO stating that they forgot to carry a zero meaning the radiation emitted is up to 10 times what they had previously admitted to! Please.

    His numbers are nudged higher or lower where it suits him. 13% of world power becomes 16% (still just shy of hydro alone). The CO2 emissions don’t include those incurred by the TEN year + construction project that precedes a plant, nor the effect of sequestering tax dollars from truly clean forms of energy like solar, geothermal and wind (technology in it’s infancy that needs those subsidies to accelerate development, unlike the MATURE nuclear industry that still relies on subsidy from the government, can’t raise private capital and is uninsurable). The audacity of this guy spouting that nuclear energy is clean DURING the Fukushima catastrophe is unconscionable! He even offers up the now cliched false dichotomy of ‘you have to have nuclear waste or CO2 – which do you want?’ – neither, in short. Tell me you people see past this stuff?

    If chaps like this are on ‘not for profit’ boards that ‘advise’ the government on the effects of radiation, then all is lost. Why is he on the board? Does he have that much free time? Is he really that benevolent?

    What can he tell us of internal emitters? Why was the the organisation that was set up to study the effects of internal emitters disbanded almost as quickly as it formed during the birth of this industry decades ago?

    Why does the IAEA have anything to do with what the World Health Organisation researches?

    Why were the remaining ‘dangerous’ reactors 1, 2 and 3 at Chernobyl still allowed to operate up to 14 years after number 4 exploded?

    These people choose to burden you with the risk.

    The Solution:

    We are probably in a position now where it isn’t feasible to turn all the plants off but it is clear that the industry needs to shrink, given it’s risks relative to the alternatives. We must cease development of ‘new’ plants (the ones being built on the cheap in asia etc. are old style BWRs not the new type that produce weapons grade plutonium) and upgrade the safety of existing plants or shut em down if they are a liability. This is difficult when nuclear energy is regulated by the IAEA who’s mission is to expand it’s use.

    For your average Joe that works with fission – retrain. You’ve backed a lame horse that has the potential to wipe out large swathes of the audience you play to.

    Commodity driven energy is not necessary, the people profiting from those commodities would like to convince you otherwise.

  8. Joffan

    Tom – fair point on design responsibility. It is a tough task that nuclear plant designers take upon themselves to assess the worst case of everything that can possibly happen to a plant. We should always allow the possibility of improvement, though, too – in this case, new understanding after construction of the geological faults.

    I don’t think “underground” should be taken as automatically better for nuclear plants, though. Surface facilities have advantages too. And dry cask storage is pretty well invulnerable.

    sd – the diesel generators stopped when they were immersed in salt water, not because they ran out of fuel. The position of the tanks is something else that could have been better, though.

    Learning from failures is what engineering does. This process efficiently produces amazingly reliable products. So I think your apparent dismissal of “learn from this” is misplaced – we will learn from this and produce better nuclear plants as a result.

    As an important side point, we should understand what “safe” means. Like “tall” and “heavy” it is a relative description. “Absolutely safe” should be a joke phrase, and it is a failing of modern communication that it is taken seriously.

  9. sd

    They put the diesel tanks right on the shoreline, there is aerial photography that clearly shows the tanks right on the edge, and then later, completely swept away. For a critical function, that is beyond irresponsible. Sure the gensets ran for 1/2 hour…until their daytanks tanks ran dry.

    Sure we could all “learn from this” and move on. And perhaps a 99.999% failsafe failure system could be setup, but the basics of human nature are the real issue we have to contend with, greed, denial, and unstable economic and political time lead people to the worst of strings of decisions.

  10. Tom Murphy

    “At Fukushima, from what we know at this time, it’s also plain that situation arose, not from human error in design or operation, but rather from the most extraordinary and unprecedented natural disaster in human memory—and what’s more, it was the tsunami wave, not the earthquake, which occasioned the loss of power and therefore challenged the cooling of the reactors. ”

    No, the accident at Fukushima was the result of a human error in the design.

    An assumption of the maximum waver height was made in the plant design basis.

    That assumption was wrong. The plant design basis is one of the earliest steps in designing a plant and the human error was made right there, at the plant’s inception.

    Nuclear power generation needs to design and build “walk away safe” plants – no operator action required, able to withstand loss of all power and loss of the heat sink.

    And we should build them underground as well. Think of it as each plant already having its own Yucca Mountain storage facility.

  11. Joffan

    Small correction: Chernobyl reactors did not use highly-enriched uranium. I believe it was somewhere between natural uranium (0.7%U-235) and “slightly enriched” 2%U-235. Less enriched than US reactors, anyway.

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