Is this the end of the nuclear revival?

''Nuclear power could make a significant contribution to the global electricity supply. Or it could be phased out - especially if there is another accidental or a terrorist-caused Chernobyl-scale release of radioactivity.''

International Panel on Fissile Materials, independent expert evaluation on The Uncertain Future of Nuclear Energy, September 2010.

Editor Professor Frank von Hippel.

''This is definitely in the Chernobyl league now. If the reactors go, that's bad, of course. But the real concern at this point is if those … spent-fuel pools catch fire. There are many Chernobyls' worth of radioactive material in there.''

Frank von Hippel, Princeton University nuclear physicist, quoted in The Christian Science Monitor, March 15, 2011.

THESE are confronting, confounding days for the nuclear industry's true believers. Physicists, technicians and the unlikeliest of bedfellows - atomic industry profiteers and green disciples of nuclear's clean-energy credentials - began the week espousing faith in the rigour of modern safety systems; emphasising the superior health record of nuclear processes over the heavy casualties routinely associated with the coal industry; and dousing super-heated media and anti-nuclear commentary with buckets of cool, technical, rational analysis.

But then the news from Japan's devastated Fukushima nuclear reactors just kept getting worse.

''The situation is very serious,'' observed Dr Ziggy Switkowski, physicist, long-time champion of nuclear power and, until a few months ago, chairman of the Australian Nuclear Science and Technology Organisation (ANSTO).

''I must say I'm not as optimistic today as I was at the beginning of all this because of the difficulties of getting control of the situation,'' he told The Age on Thursday as the emergency escalated.

Questioned on the implications of the Japanese emergency for the future of nuclear as a clean, reliable alternative to polluting coal energy - the qualities that have underwritten the much-hyped ''nuclear renaissance'' in recent years - Switkowski said the situation was still too fluid to be making any forecasts. ''[But] I expect there will be many months of review of the situation, and those reviews will reveal important insights.

''And the history of the industry is that it will very quickly incorporate those into changes in design and procedures.

''I strongly believe in the safety of nuclear reactors,'' he said. ''But I don't think you can say you can design anything that will withstand the forces of nature we've seen in the past week.''

Meanwhile, John Borshoff, a veteran Australian uranium miner and exporter who has held the faith on nuclear for decades but whose Perth-based company, Paladin Resources, was devalued by $1.3 billion this week, was still defending the safety record of nuclear power, still unwavering in his belief in its capacity as the only clean alternative to coal, and still withering in his critique of alarmists and ill-informed commentators.

''The whole thing has been a media frenzy - people don't understand very complicated issues and they're trying to do it by idiotic references to Chernobyls and Three Mile Islands,'' Borshoff said, referring to the spectre of the two big nuclear accidents, in 1986 and 1979, which have loomed so large over Fukushima.

''I believe these units [in Japan] will be stabilised, that there will be damage done to the assemblies, but the fallout issues will be minimal.

''But however it turns out, I don't think it will have a long-term impact on nuclear power,'' he insists. Why? Because the global appetite for clean power is so huge.

Accumulating greenhouse gas emissions and the consequent effect on climate require an emphatic switch away from fossil fuels to clean energy and, Borshoff argues, alternatives such as wind and solar are never going to cut it.

''I won't even countenance a renewable contributing anything significant to this whole fuel issue.'' Claims to the contrary are, he says, ''bullshit … it's a joke, a cottage industry, it's hugely expensive … and only works 34 per cent of the time. It's just enough to keep people feeling warm and fuzzy.''

Equal vehemence and invective can be found among scientists and others committed to the capacity of renewables to step up to meet humanity's hunger for power.

There is strong hope among them that if any good is to come from the Fukushima emergency it might be a renewable ''enlightenment'' that simultaneously buries notions of a nuclear revival that, they argue, were always more wishful thinking than reality.

Prohibitive costs and a reluctance by markets to invest in nuclear power have seen it stagnate in the West even as fuel-hungry nations such as China (which has 13 reactors and is building 28 more), and India (which has 20 reactors and plans to build dozens more to get power to 1.2 billion people without regular access to electricity) have embarked on ambitious nuclear programs.

The upshot, says Griffith University's Professor Ian Lowe, a leading authority on energy and the environment, nuclear critic and president of the Australian Conservation Foundation, is that there has been a net decrease in new nuclear capacity coming online recently, while wind power has surged. Like Associate Professor Mark Diesendorf, an energy policy expert from the University of New South Wales, he is confident that with political will and aggressive policies and investment, renewables could meet global needs sooner rather than later. Fukushima, they hope, might provide the impetus.

The nuclear power debate has long been the most disconcerting and bewildering of arguments, the discussion frequently bogged in intractable polemic. This week it has taken a turn to the bizarre, occurring against the backdrop of incalculable anguish as the known death toll from the Japanese earthquake and tsunami climbs, a real catastrophe which has at times in the past week risked being obscured by an imagined one.

Meanwhile, the desperately needy survivors of the quake and tsunami remain hostage to fears about nuclear cataclysm with the distribution of humanitarian aid stymied by a radioactive cloud - actual or perceived.

Those attuned to the dimensions of the climate-change emergency also see another chilling scenario: what if a flight from nuclear brings about the burning of more coal, the primary driver of human-caused climate change?

China announced on Wednesday that it would follow the lead of Germany and Switzerland and pause to review its massive nuclear power program. The three-month German moratorium alone would, according to a calculation by energy analysts, add eight megatonnes of carbon dioxide emissions.

Climate-change scientists and activists are now contemplating the effects of a middle to long-term shift away from nuclear.

''I despise and fear the nuclear industry as much as any other green,'' wrote influential British climate commentator George Monbiot in his Guardian blog this week. ''[But] even when nuclear power plants go horribly wrong, they do less damage to the planet and its people than coal-burning stations operating normally.''

Ruling out nuclear, ''a low-carbon source of energy, which could help us tackle the gravest threat the world now faces … does neither the people nor the places of the world any favours''.

Back in the 1970s, it was expected that nuclear energy would soon become the world's dominant generator of electrical power. Nations such as France determinedly invested in the technology after the oil-price shock.

''Nuclear-power boosters expected that by now nuclear power would produce perhaps 80 to 90 per cent of all electrical energy globally,'' nuclear experts of the International Panel on Fissile Materials said late last year in a report tracking the fortunes of nuclear energy.

Instead, nuclear plants today account for less than 14 per cent of global electric-power generation.

While ''the routine health risks and greenhouse-gas emissions from fission power are small relative to those associated with coal … there are catastrophic risks,'' the panel wrote.

''The 1979 Three Mile Island and 1986 Chernobyl accidents, along with high capital costs, ended the rapid growth of global nuclear-power capacity.''

As memories of these accidents faded and concerns about the consequences of global warming grew, nuclear prospects were widely touted to have improved.

Nonetheless, costs compounded by the fear factor put a powerful brake on investment in Western Europe and North America, despite handsome government guarantees and subsidies which were still, this week, being pledged by President Barack Obama to US nuclear investment.

And while the International Atomic Energy Agency expects a 42 to 75 per cent expansion of nuclear capacity in East Asia by 2030 - mostly in China - even that nation's top nuclear-safety regulator has expressed concern about the speed, construction quality and operational safety of the rollout.

A key element of the IPFM report was to consider public perception and acceptance of nuclear power. Its reflections provide some insight into a dynamic that coloured reporting and commentary on the Fukushima emergency all week: nuclear specialists on the one hand underlining the overall safety record of the atomic industry; and on the other a frightened, frequently suspicious public preoccupied with what might happen, and confounded by the technical assurances of the experts. Each side viewed the other with incredulity, like creatures from two different planets.

''Public perception of risk has been something of a puzzle to many technical experts, since they do not view the risk to the public from nuclear plants as being especially high,'' the IPFM report explains. Technical experts express risk in terms of probability, as in injuries and deaths per gigawatts of electricity generated.

Applying such accounting, even the 16,000 extra cancer deaths calculated to have occurred as a result of the Chernobyl disaster were ''rather modest'' in production terms compared with occupational and air-pollution deaths associated with coal-fired power.

As the IPFM concluded, ''the public … is more sensitive to other characteristics''. Fear of nuclear cataclysm is not necessarily rational. It is entwined with fear of the uncontrollable, dread of the unknown and dangers that cannot be seen, suspicion about the safety of systems and mistrust of the competence of the nuclear establishment and governments to manage nuclear power safely.

The words and images broadcast out of Fukushima all week will have done nothing to alleviate those concerns. By yesterday, both the conservative London Telegraph and the liberal Guardian were quoting Europe's energy commissioner, Guenther Oettinger, saying: ''There is talk of an apocalypse and I think the word is particularly well chosen. Practically everything is out of control. I cannot exclude the worst in the hours and days to come.''

What happens to the nuclear industry from here will depend on what happens next at Fukushima, according to Associate Professor Tilman Ruff, a public health specialist at Melbourne University's Nossal Institute for Global Health and chair of the International Campaign to Abolish Nuclear Weapons. And anything could yet happen - ''the situation is so unstable, so unpredictable, so unprecedented, you'd be a brave person to make any kind of prediction.

''If there is a major release from either a spent fuel holding pond, or from a reactor core, or both or, in the worst-case scenario, multiple releases, I'd be very surprised if that didn't stop the industry dead in its tracks. Or dent it for a very long time.''

Figures released by Tokyo Electric Power on Thursday show that most of the dangerous uranium at the power plant is actually in the spent fuel rods, not the reactor cores. It said that 11,195 spent fuel assemblies were stored at the site, in addition to 400 to 600 assemblies that had been in active service in each of the three troubled reactors.

The stability of the spent fuel rods depends on the ability of emergency workers and engineers to keep them covered by water.

''So you've got very large amounts of very long-lived radioactive isotopes sitting in the swimming pools with no containment structure, and a high risk of igniting if exposed to the air,'' says Ruff.

The crisis brings into sharp focus the bottom line of the anti-nuclear mantra: that there is no safe place for nuclear waste, and no guarantee against unforseen, critical events. ''There is just nothing else that is as toxic for as long, and that needs to be isolated from the human environment over such vast time frames, geological time frames.''

If there were going to be any positive consequence out of the emergency, says Ruff, ''it would be if there was a serious decision - and we're already seeing signs of this in Germany - of phasing out nuclear power. Of putting the massive resources that go to nuclear … cleverly redeployed into renewables and particularly into efficiency gains.''

Diesendorf expects events in Japan will see nuclear power continue its decline - ''despite the claims of its proponents, it is already an industry in stagnation'' - and will drive renewable expansion. ''China and India were doing a lot already on renewables … enough to wipe out nuclear.'' He foresees increasing emphasis on wind, on solar, and on concentrated solar thermal power.

Ian Lowe takes a similar line. Fukushima will ''derail even the limited progress the nuclear industry was making in trying to talk itself up as a solution to climate change''. Unlike Monbiot, Lowe is not anticipating a retreat to fossil fuels.

''There are people who say that the consequences of climate change are so scary that the consequences of embracing nuclear power on a large scale are less worse - and that is a defensible view. But that's a value judgment. It's also a value judgment whether you scale up nuclear power without having more Fukushimas or more countries such as North Korea or Pakistan or Iran using the technology. The undeniable fact is that the technical capacity that allows you to generate nuclear power also gives you the technical capacity to produce nuclear weapons.''

But Professor Barry Brook, who holds the chair of climate change at the University of Adelaide and is a strong advocate of nuclear energy to reduce greenhouse emissions, argues the technology remains ''the only satisfactory replacement for coal''.

He doesn't think the events in Japan will do more than momentarily pause such programs as the Chinese nuclear rollout. ''The reactors being built in China today, the generation-3 class reactors, are 40 years more mature than the ones at Fukushima. They already have passive systems in place such that they would not have encountered the problems the Japanese reactors have encountered.

''In Australia, I think the nuclear power debate is off the table now for five years. I don't think any political party will have the guts to touch it. That's not based on a scientific or engineering rationale, that's based on the way politics works in Australia.''

He expects the issue will re-emerge when it becomes clear that Australia cannot meet its emissions reduction targets any other way.

''If they can get significant wind and solar and so forth going, then great. I'm not pro-nuclear because I'm anti-renewables, I'm pro-nuclear because I see it as the only realistic solution to replacing fossil fuels. If I am proven wrong, I will only celebrate.''