The Upside Down Book Of Nuclear Power

By Saurav Jha

A guide to understanding issues related to nuclear power as energy source Arcane discussions on nuclear power have been confounding people for a long time. The Upside Down Book of Nuclear Power is an attempt to demystify this critical area of public choice for the general reader. While it does not forego the seriousness associated with the topic, the book provides for an easy read that informs the reader of a variety of issues associated with the subject. Divided into short chapters, aspects such as technology, resource availability, economics, geopolitics and policies associated with nuclear power are dealt with in detail, but in a way that emphasizes readability. Contentious areas such as safety, waste management and the latest trends associated with them are laid bare for the reader. The book also dwells in depth on the shrill and seldom above-board debate on nuclear power and renewables. An invaluable companion for all those looking to understand the nature of the nuclear industry in the new millennium and the implications of international treaties such as the Indo-US nuclear deal. 

• Language: English
• Publisher: HarperCollins
• Release date: Jul 21, 2012
• ISBN: 9789350292532

Saurav Jha

Saurav Jha studied economics (and debated politics) at Presidency College, Calcutta, and Jawaharlal Nehru University, New Delhi. He dropped out of the PhD programme to do some explorations of his own. He writes and researches on global energy issues and is passionate about clean energy development in Asia. He is currently writing a Tom Clancy-ish techno-thriller, defence and military history being his other great loves. He has started his own energy advisory-Energy India Solutions-based in Delhi and Calcutta.

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Preface

THE FUKUSHIMA EFFECT

Even as I write this, hundreds of thousands in Japan are struggling to rebuild their lives in the aftermath of one of the strongest earthquakes in recorded human history, and the killer tsunami that followed in its wake, in the late-afternoon of 11 March 2011. In the midst of this tremendous human tragedy, however, it is the nuclear incident at Fukushima that seems to have grabbed maximum coverage. Like in the 1980s, bad news sells – radioactive bad news sells even better.

But pause we must. And in the vein of this book, objectivity should not fall prey to radiation. Nuclear abolitionists seem to believe they now have a barrage of evidence to check the onrush of the global nuclear tide we have seen ever since governments the world over realized that any strategy to fight global warming must necessarily have a nuclear component. The reasons for that thinking remain sound, despite Fukushima. As I have argued elsewhere in this book, nuclear power remains the only alternative to coal-based generation for large-scale industrial and commercial purposes (see A for An Introduction). According to a recent study by the UK government which classifies nuclear as a renewable source:¹

* Recent estimates indicate that its costs (including those for decommissioning and waste) are among the lowest of the low-carbon options.

* Given its capital intensity and low marginal cost of generation, it is best suited to operating at baseload.

These two arguments for nuclear power pretty much sums up the crux of the case made in its favour, especially in countries such as India and China which have to industrialize to pull thousands out of penury, yet cannot do so at the cost of the environment.

Of course, Fukushima does raise hard questions about issues such as nuclear siting, spent fuel management, and just which type of existing reactors ought to be retired – and how soon. These are pertinent questions and, as I have maintained throughout this book, must always be subject to public scrutiny in order to keep the nuclear industry on its toes. But once again, informed debate must not be supplanted by mass hysteria as that can lead to adverse choices. For instance, one of the main reasons why the reactors at Fukushima were not retired in the late 1990s was that the post-Chernobyl cancellation of newer reactors had forced the Japanese utility, Tokyo Electric Power Company (TEPCO), to continue with what are essentially Mark1 boiling water reactor (see M for Many Different Types of Reactors) designs from the 1960s. The same situation holds true for a number of reactors in Eastern Europe which should have been decommissioned and replaced by now.

Before we comment on the aftermath of Fukushima, it would be worthwhile to consider the sequence of events that unfolded in the course of the biggest crisis in nuclear industry since Chernobyl. Let us take a look at what happened at the affected reactor Units 1, 2, and 3 at Fukushima Daichi since they were hit by tremors measuring 9.0 on the Richter scale at 2:46 p.m. on 11 March 2011.

FORCE MAJEURE

Chain reaction shutdown: As motion sensors at the three units recorded the earthquake, neutron-inhibiting control rods were automatically inserted into the reactors, leading to a rapid shutdown of the chain reaction, which meant that fission of the uranium fuel would no longer take place. However, radioactive intermediate products that result due to the fissioning of uranium, such as cesium-137 and iodine-131, continued to undergo natural radioactive decay and release heat. This heat – which is about 2 per cent of the total heat generated in a reactor while in operation and is known as residual or decay heat – began to be removed via the auxiliary residual heat removal (RHR) system, which is powered by electric pumps, since the primary cooling system was no longer available on account of the loss of grid power due to the earthquake.

Loss of emergency diesel generators: On account of being in shutdown mode, the respective RHRs at the three reactors had to be run by back-up diesel generators as mains power was no longer available. Things were on course for fifty-six minutes before the 14-metre high tsunami struck the site. Fukushima Daichi had been designed to cope with tsunamis less than half that height and the result, unsurprisingly, was the destruction of the diesel generators. The operator then switched to eight-hour battery packs to keep another back-up decay heat removal system operational – the emergency core cooling system (ECCS). The ECCS uses both high-power and low-power coolant injection systems which are used to pump water into the core in the event of a loss of coolant accident (LOCA). As the battery back-up failed to provide adequate power to run the valves used by the ECCS, it failed in all three units, and since the operator wasn’t being able to pump enough coolant into the pressure vessel (PV) of the reactor which contains the fuel rod core, the temperature in the core started rising and steam began to build up in the PV. In order to relieve this pressure buildup, the steam was vented through emergency pressure valves in a controlled manner, in the space between the primary and secondary containments surrounding the PV.

Explosion: The explosions at Units 1 and 3 – shown so dramatically on television screens – were the result of the reaction between hydrogen, which had built up near the roof of the outer containment of the reactor, and ambient oxygen. Hydrogen is typically produced in superheated steam, due to the splitting of water into hydrogen and oxygen. But in the case of Fukushima, it was primarily produced due to the interaction of the overheated Zircaloy fuel cladding and the steam.

Partial core meltdowns and radioactivity of the vented steam: Indeed, partial core meltdowns have taken place in two reactors in Fukushima and that is chief reason why the vented steam contained significant amounts of radionuclides such as Iodine-131 and Caesium-137.

The main radionuclide released from among the many kinds of fission products in the fuel is volatile iodine-131, which has a half-life of 8 days. Iodine-131 decays to inert and stable xenon-131. The other main radionuclide is caesium-137, which has a much longer half-life and may contaminate land for some time. In assessing the significance of atmospheric releases, the Cs-137 figure is multiplied by 40 and added to the I-131 number to give an ‘iodine-131 equivalent’ figure.

Source: World Nuclear Association

Seawater: After all active systems had failed to remove decay heat at Fukushima Daichi Units 1-3, TEPCO injected seawater laced with boric acid, which is a neutron inhibitor, into the reactors in an attempt to cool the overheated cores. However, this also meant that these reactors are effectively written off since seawater is highly corrosive.

Unit 4 and used fuel storage: Unit-4 which was not operating at the time of the earthquake developed problems of its own in the days after the crisis. The spent fuel pond in this unit experienced a drop in water levels, thereby exposing the fuel rods which led to their overheating and the melting of the zircaloy cladding protecting them. The zircaloy reacted with steam to form hydrogen which collected near the roof of the outer containment in a manner similar to Units 1 and 3 and eventually exploded on interaction with oxygen, resulting in a fire which took three hours to put out.

It may take a while: At the time of writing, external grid power had been restored to all units at Fukushima and normal water was being injected from time to time to keep the cores from melting any further as well as to keep the spent fuel ponds topped up. However, in addition to the radioactivity released via the vented steam, there have been leaks of radioactive water from at least two of the stricken units. While these leaks were subsequently plugged, it nevertheless shows that it will take a while before Units 1-3 at Fukushima attain cold shutdown condition with all the residual heat removed. TEPCO believes that a six-month timeframe is required to bring the situation under complete control that would allow residents to return to their homes in the thirty-km radius exclusion zone around the plant.

WILL THIS BE ANOTHER CHERNOBYL?

At the beginning of the crisis, Fukushima Daichi was given a level-4 rating on the international nuclear event scale (INES) by the IAEA as it was seen as an ‘accident with local consequences’. Subsequently, it moved up to INES level 5 which is the same as the Three Mile Island incident in 1979. But, in early May 2011, the Japanese NISA declared the situation to be an INES level-7 event which is the highest possible rating on this scale and one accorded only to Chernobyl in the past. The IAEA accepted NISA’s rating on a provisional basis, on account of the large release of radioactivity from Fukushima since the beginning of the crisis.

However, the IAEA was quick to point out that Fukushima and Chernobyl are ‘very different’² and emphasized that the accident at Chernobyl still ranks as the worst nuclear accident in history. Indeed, both in absolute and relative terms, Fukushima is nothing like Chernobyl. For one, the amount of radiation released by Fukushima till now is only a tenth of what was released from Chernobyl. Moreover, while the radioactive release from Chernobyl was near instantaneous on account of an explosion which blew fuel elements directly into the atmosphere, eventually leading to its spread around the world, Fukushima’s reactors have leaked much less radiation over a much longer period of time. This is important because although radioactive doses do accumulate in the blood, acute radiation syndrome(ARS) results essentially from being exposed to a very high amount of radiation in a short period of time.

Moreover, it must be noted that the mechanics of the accidents are divergent. While Chernobyl was caused by flawed design and incorrect operator actions, the Fukushima crisis occurred in consequence of terrible natural events of rare intensity. But even then, as far as casualties are concerned, in Chernobyl, twenty-eight workers died on the spot from the steam explosion and fifteen more died later due to ARS. Three workers lost their lives at Fukushima – two died when a crane fell on them as the earthquake hit the land, and one perished in the tsunami.

As Ben Monreal, physicist at UC Santa Barbara, noted, ‘The worst-case radiation hazards from Fukushima are mitigatable and local, with the global radiation hazard being nil and the best way to reduce worldwide low-level radiation releases is to stop burning coal.’³

WHO MOVED MY LIABILITY?

The really big question surrounding the Fukushima disaster is the nature of the compensation package and who gets to foot the bill. Japanese nuclear liability law mandates that the operator is exclusively liable for any damages, and damages might be unlimited in scope. It further mandates that the operator set aside 1.46 billion dollars as a security amount per reactor, for which it can draw insurance. However, in the case of a ‘grave natural disaster of an exceptional character or by an insurrection’, the liability law exempts the operator and enjoins upon the state to bear the cost of compensation beyond the indemnity amount.

In the weeks after the crisis, TEPCO sought just such a reprieve, pleading that the Fukushima incident does indeed qualify as having resulted out of a ‘grave natural disaster of an exceptional character’ and that its liability be limited to the indemnity amount. Unfortunately for TEPCO, Japan’s government actually blamed it for not foreseeing the crisis, and ruled that there would be no ceiling set on TEPCO’s liabilities. The decision proved rather contentious as TEPCO’s creditor banks averred that such a move would be self-defeating, as unlimited liability would degrade TEPCO’s credit rating to junk status, thereby making it absolutely impossible for it to secure the compensation amount from the market.

Truth be told, the Japanese government faces a rather precarious situation. On the one hand, it has to contend with massive public debt (some 225 per cent of GDP) which means it has very little latitude to help TEPCO financially, while on the other hand, the prospect of Japan’s largest bond issuer (i.e., TEPCO) going under might destabilize the entire domestic financial market. It also has to balance rising public anger at the utility with the pleas of an industrial sector reeling under the effects of the tsunami.

As such, a compromise solution seems to have been worked out, whereby TEPCO has agreed to government oversight for structural reforms, an enquiry into its senior management’s decision makinl geading up to the crisis and unlimited liability in return for a government aid package drafted with other utilities.

The total compensation package for Fukushima is likely to be in the range of fifty billion dollars, with half of that being borne by TEPCO, and the remainder from a common pool of eight other domestic nuclear plant operators, who will contribute in proportion to their electricity output. TEPCO’s payments will be made over a ten-year period, with 50 per cent of it being financed by a 16 per cent hike in electricity tariffs. TEPCO will not issue any dividends in this timeframe.

HOW WORRIED SHOULD INDIA BE?

The Fukushima incident has certainly provided a fillip to naysayers of nuclear power in India. Their opinions now range from pure propaganda (tens of workers dead, thousands affected by radiation) to more informed views bringing into question matters such as site selection and technology choice.

The chief question that naturally comes to mind is whether Indian reactors are located in seismically active zones or not. Well, with the exception of the Narora Atomic Power Station (NAPS), all Indian nuclear power stations are built in Zone 2 (low seismic activity), unlike Japanese reactors, which are in Zone 4 and 5 (high seismic activity). NAPS is, however, located in Zone 3.

Nevertheless, in a testament to the build standards of Indian reactors, it ought to be remembered that Kakrapar Atomic Power Station remained operational even after it experienced the Gujarat earthquake of 2001 which measured 7.7 on the Richter scale and provided much needed electricity to aid the subsequent relief effort.

It is also important to keep in mind that removal of decay heat is a problem that has occupied the minds of reactor designers for over three generations now, with the Indian nuclear community being no exception. The dominant Indian reactor type as of today is the Indian pressurized heavy water reactor or IPHWR, the average age of which is less than twenty years. Research on this type has been consistent and a number of safety improvements have been effected over the years. IPHWRs consist of two-reactor shutdown systems, one of which uses control rods and the other consists of a liquid poison injection system. This combination guarantees that the chain reaction will be shut down rapidly in the event of a major earthquake.

However, like Fukushima, subsequent to the chain reaction shutdown, there will be a need to remove the decay heat. And like Fukushima, where the primary cooling system failed due to an unavailability of grid power, IPHWRs will also use active auxiliary systems such as the RHR and ECCS to do the job. The ECCS in IPHWRs is triple redundant, consisting of a high pressure coolant injection system, a pool of light water maintained in the calandria housing the core, and a suppression pool.

Nevertheless, the RHR in Indian reactors is also an electrically powered system and may itself be unavailable on a sustained basis due to the unforeseen breakdown of back-up systems such as diesel generators, as evidenced by Fukushima. Subsequently, the ECCS may also fail due to Fukushima-like power blackout conditions. In such an eventuality, IPHWRs rely on a passive decay heat removal system based on the ‘thermosiphon effect’ which exploits the elevation difference between the steam generators and the reactor core.

Interestingly, the thermosiphon effect proved its efficacy in the NAPS fire incident of 1993, which was characterized as an INES level-3 incident by the IAEA and involved the loss of power supply to the reactors in a manner similar to what happened at Fukushima. India has also retrofitted Tarapur1 and II – which are BWRs of the same vintage and type as the units at Fukushima – with emergency condensers that would allow the thermosiphon effect to be used in the event of a complete blackout.

Greater redundancy also seems have been built into Indian reactors by stationing an additional diesel generator, an additional air compressor and two fire water pumps over the maximum anticipatel devel of flooding. This generator could prove useful in both powering the RHR as well as pumping fire water into the steam generators in a situation where the other generators are washed away, as was the case in Fukushima. Indeed, there is now a case for having more such installations and a review of the height at which this is done, considering that Fukushima was hit by forty-five-foot-high waves. In fact, the elevated stationing of diesel generators proved rather useful in shutting down Madras Atomic Power Station when it was hit by the Indian Ocean tsunami in 2004. Readers would note that the reactor was brought back online, within a week.

BUT WHAT ABOUT IMPORTED REACTORS BEING BUILT IN INDIA?

Kudanakulam was also hit by the Indian Ocean tsunami in 2004. However, the two Russian-origin reactors undergoing construction did not face any hassles with the rising water levels as their defence-in-depth features had been specifically designed to withstand such calamities. All buildings at the plant had been designed to rise from 7.5 m above the mean sea level (MSL) to take care of flooding due to natural events such as tsunamis, and a shore protection bund rising to a height of 7.5 m above MSL was built at the site as an additional measure. Each reactor at this site will have four redundant back-up diesel generators even one of which would be enough to power the RHR system. These back-up generators will be kept at a height of 9 m above MSL.

The Kudanakulam reactors are also equipped with core melt catchers and are fitted with passive hydrogen re-combiners that prevent the accumulation of hydrogen in the containment structure by converting it back to water. This means that the chance of a hydrogen explosion occurring at one of these reactors a la Fukushima is negligible.

Most importantly, in the event of a loss of power to the active decay heat removal systems, large-capacity steam generators kepa tt higher elevation to the core will help cool the reactor through the thermosiphon effect. The steam generator water itself is cooled by a passive air cooling system, working on the principle of natural convection without the need for any electrical power.

Indeed, all imported reactors scheduled to be built in India (including the ones at Kudanakulam) are Gen III+ designs and are equipped with passive safety measures that cater to the removal of decay heat and are driven by gravitation or convection. These systems allow the operator a much greater margin for removal of decay heat than was available in the case of the Fukushima reactors.

THE WILFUL GAINERS

Every crisis brings forth opportunity for some. But to understand how that might be in the case of Fukushima, we must look at why Japan adopted nuclear power in the first place, given that it is an island nation sitting right astride the Pacific ring of fire.

Following its defeat in the Second World War, Japan realized that one of the reasons that had led it to seek empire through that conflict continued to haunt its industrial growth – an acute shortage of national hydrocarbon resources. Ironically, though, the effort to harness nuclear technology for warfare – that had resulted in such tragic loss for the people of Japan – had also created the means by which it could alleviate its energy handicap. And under Eisenhower’s Atoms for Peace program, Japan became an early beneficiary of American attempts to spread civilian nuclear power throughout the world.

Nuclear energy was a clearly a good option to power Japan’s postwar economic rise since it could generate electricity continuously over a very long period of time and at very high capacity factors – key features for meeting demand from energy-intensive industrial and commercial activities. Moreover, nuclear energy also gave Japan a certain degree of freedom from geopolitics. Japan, which till the 1973 oil crisis used to generate about 66 per cent of its electricity through oil-fired generators, uses the same source for only 11 per cent of its requirements today, while nuclear power supplies 30 per cent of Japan’s electricity.