Hans Blix: Risks from Nuclear Sources in the 21st century

Hans Blix, former director of IAEA and chairman of the WMD commission, spoke at the symposium "Nuclear Riks - Safety and Security" held in connection with the 150th anniversary of the Norwegian Academy of Science and Letters in 2007. This symposium is organized in cooperation with the Norwegian Polytechnic Society.

Let me begin by expressing my respectful congratulations to the 150 year old Academy. It is a great honor for me to address this meeting.

A famous American once told me that he respected people who search for the truth and felt some concern about those who have it.

I am happy that the symposium has been asked to discuss nuclear risks. It is a subject on which many feel they have truth. As they differ I think we can do no better than pursuing in all humility the search that science requires.

Having said this I shall proceed to tell you the truth, the whole truth and nothing but the truth…

  • My topic is ‘risks from nuclear sources’ and I shall focus on risks connected with nuclear power.
  • The first half of my presentation will deal economic and safety related risks. The second half will deal with risks relating to nuclear weapons.

A preliminary remark:

  • Although it is possible to assess the risks of almost any activity in isolation, some awareness of the risks and benefits of alternative options – if there are any – will put these risks in perspective.  
  • Thus, when we examine the risks of using or expanding the use of nuclear power, we might do well to ask what risks or other negative effects there would be if we refrained from calling for more energy or if we used other options than nuclear power. 

IS THERE A NEED for MORE ENERGY – nuclear or other?

  • The famous Indian nuclear scientist, Homi Bhaba said that ‘no energy is more expensive than no energy’. You understand what he meant when you see pictures of women carrying big bundles of wood on their shoulders or pails of water on their heads you sources.
  • In the pre-industrial society we relied on our own muscles or on draught animals to pull and carry. In the modern society tractors plow the fields and trucks carry the grain. We went from rowing with our own arms to sailing with the wind and to steamers relying on coal, then to diesel powered ships. Nuclear powered ships – ice breakers, aircraft carriers, submarines – proved sturdy and reliable, but concerns about safety stopped the development of commercial cargo ships.
  • In the high-energy society we get less exercise but we also get less worn out and live longer. Few want to go back to the older ways of living. They ask for more energy to make their lives less burdensome.
  • While a more efficient generation and use of energy is acknowledged as important, limiting the use of energy is hardly an option anywhere: This is not surprising where the annual use of electricity is very low – even below 100 kWh – but demand increases also in countries like Norway, where over 20.000 kWh electricity is used per capita and year.
  • One reason for the increased global demand for energy is that the world population is growing. Some figures are telling:
  • At the time of Christ there were – it has been calculated – some 350 million people on the Earth
    -- by the year 1900 we had become 1.5 billion;
    -- in 1900 we had attained the 5 billion level; and
    -- in the year 2000 we were around 6 billion.
  • Thus, in the last decade of the 20th century we increased by roughly the same number as we did during the 19 centuries from the time of Christ. Although, fortunately, the increase is slowing we know there will be many more people asking for more energy – especially electricity that is clean and efficient in end use.
  • We must conclude that if nuclear is not used, some other source will be relied upon to generate more energy.  The various risks that we link to any use of nuclear power should therefore be compared with the risks that would be incurred by the use of alternative sources. I propose to discuss risks regarding
  • Economy
  • Assurance of supply of fuel
  • Safety in operation
  • Safety in waste disposal
  • Security


  • In the early phase of the nuclear era, nuclear power was hailed as ‘too cheap to meter’. However, building and operating nuclear power plants, like most other things, turned out to carry economic risks – as many utilities painfully experienced.
  • Although the uranium fuel is not expensive and is a very small part of the cost of nuclear electricity, the construction of nuclear plants was and is expensive compared to the construction of, say gas and coal plants.  The nuclear construction time is longer and interest has to be paid on borrowed capital for a long time while no revenues yet come in.
  • In the 80s and 90s the construction of nuclear power plants stagnated. A large number of planned nuclear power plants were cancelled, especially in the US. Why?
  • Opposition to nuclear power and uncertainties in the regulatory climate after the TMI accident caused construction delays and certainly played a role. However, the economics may have been even more important.
  • The increase in the demand for electricity in industrialized countries turned out to be lower than had been expected: it no longer followed the increase in GDP as it had done earlier in industrialized countries.  Furthermore, new combined cycle gas powered plants could be built faster and cheaper than nuclear plants and they could more easily adapt their operation to fluctuations in demand than the nuclear plants that are most economic to serve a continued base load.
  • In East Asia – Japan, South Korea and China –the steadily increasing demand for more base-load electricity made nuclear power look less of an economic risk and more such plants were built even in the 80s and 90s. However, while in China today the number of nuclear power plants is increasing we should note that at the same time the number of coal powered plants is skyrocketing.
  • At the present juncture an increased demand for nuclear power is expected in many parts of the world.
  • One important reason is that it contributes hardly any green house gases;
  • Another reason lies in the rising prices for oil and gas. While the price of uranium has also increased, it forms a small part of the cost of nuclear electricity. And while the cost of construction of nuclear plants has gone up, their economy has improved through an increase in availability for operation from some 70 % to over 90% and through a lengthening of their technical lifespan from some 30 to some 50 or more years.


It is sometimes pointed out that uranium resources are finite and that the presently known resources will only last some 50 years of operation of the present park of nuclear power reactor. Long term this would not, it is argued, make for a viable nuclear power industry.

However, currently only a small part of the energy content of the uranium in the fuel rods is used in most countries. If the demand – and price – for uranium increased because of a greater use of nuclear power, it would become economic to reprocess the spent fuel and recover large quantities of uranium and plutonium now not used. Some 80 to 100 times more energy could be extracted from the uranium making the resources sufficient for much more nuclear power and far into the future Let me give some figures comparing the energy content of different fuels:

1kg of wood has an energy content corresponding to 1 kWh

1 kg of coal --------------------------------------------- to 3 kWh

1 kg of oil ----------------------------------------------- to 4 kWh


1 kg of uranium ---------------------------------------- to 50.000 kWh,

If it is reprocessed after use, the U and Pu will have

An energy content corresponding    ---------------- to 3.500.000 kWh

I should make two more comments on the availability of fuel

First, while much of the world’s oil and gas resources are found in politically volatile areas the largest currently mined uranium resources are found in Australia and Canada.

Second, that thorium, which is plentiful in Norway and India, could be a future fuel for nuclear power reactors. It is calculated that the thorium resources of the earth may be three times as great as the uranium resources.


  • When talking about ‘nuclear risks’ most people think first of all about big nuclear accidents, like Chernobyl or Three Mile Island. Some ask whether our societies can continue to take the risk of such accidents?
  • We must be aware first of all, that hardly any energy generation occurs without risk of accidents, whether in the extraction or transportation of fuel or the actual operation of plants. I shall talk separately about the handling of waste.
  • Nuclear differs from other risks in the lasting radioactive contamination that it may cause – and did cause in Chernobyl in 1986. However, we should also remember that Chernobyl was a unique case, occurring in a rare type of reactor that lacked containment. Most of the world’s light water reactors have a containment that stops any emissions of radioactivity into the environment.
  • The Three Mile Island accident that occurred in 1979 in a common type of power reactor was an economic disaster but no emissions occurred into the environment. Modern power reactors are constructed to give even greater guarantees against emissions into the environment.
  • One must note, further that studies reveal that the most severe accidents in the field of energy have occurred in hydropower. When big dams have burst – as has happened not so rarely – huge quantities of water have been released and flooded downstream towns and villages with horrendous losses in lives. Gas drilling platforms and coal mines also take a toll of victims, as do exploding gas pipelines.
  • The risk of nuclear accidents is not zero but we must note that – as in other industries – lessons are learnt. During the 19th century explosions were common in boilers until better routines and controls were developed. We hardly hear of such accidents any more. Since the Chernobyl accident 20 years ago we have not had any nuclear accident with significant releases of radioactivity.


The argument has often been made that our generation cannot take it upon itself to create waste that will remain hazardous for tens of thousands of years. It has also been said that people have such an abhorrence for highly radioactive waste that no country has been able to take a decision on a repository for it.

Let me say, first, that it is important that action should be taken to eliminate any risks connected with waste from past military activities – in the US, Russia as elsewhere;

Secondly, that  it is welcome that a new shelter around the fourth destroyed reactor at Chernobyl is about to be built and that wastes will eventually be removed;

Thirdly, that Finland has become the first country to begin building a final repository for high level waste and that in Sweden the authorities of two different regions are competing to receive the Swedish final repository.

Fourthly, that it is important that research continue to develop nuclear technologies that will result in less waste and technologies that can drastically shorten the time during which the waste will remain hazardous.

Fifthly, that even though the repositories should be capable of harboring the high level waste forever, it should preferably be retrievable for a prolonged period of time. A wise president of a Swedish Commission on Waste, Ms. Odhnoff, once said ‘waste is what remains when our imagination has run out.’ What we judge to be waste today, we may find contains something valuable to-morrow.

Lastly, we should not talk only about ‘alternative energy’ but also about ‘alternative waste’. It is sometimes said that there are two principal ways of dealing with waste. One is called the C and C method, meaning concentrate and confine. That is what we do with the nuclear waste. We take care of it in its entirety, encase it in several layers and place it deep in stable geological formations in the crust of the earth.

The other method is D and D: dilute and disperse, which is what we do with the waste from burnt fossil fuel. The wastes from coal, oil and gas are so enormous that we have not been able to take care of them but release them into the atmosphere or leave them on the ground. They contain toxic heavy metals like mercury, lead and uranium that do not even have half lives.

And they contain CO 2, the most important greenhouse gas that threatens climate change. It is certainly to be hoped that it will be possible not only to separate and sequestrate the CO2 that may come from gas field but also to catch and bury CO2 that is produced when coal is burnt to generate electricity.


I come now to questions of security related to nuclear energy.

Can we have nuclear power and escape the threat to our security posed by nuclear weapons, or are they inextricably linked, like Siamese twins?

If we double or tenfold the number of nuclear power plants in the world from some 450 now to 900 or to 4500 in a future, would the risk inevitably increase that enriched uranium or plutonium went astray and led to an increase in the number of states or groups that have nuclear weapons?

Nuclear weapons, it is true, cannot be uninvented. The genie is out of the bottle. Much of the technology is available on the Internet. The reprocessing plant that the North Koreans used to obtain plutonium is of an old-fashioned type described in text books. The enrichment plants that were in operation in Iraq in 1991 were of a type invented long ago in California – Calutrons.

However, if nuclear weapons cannot be un-invented, they can be outlawed – like biological and chemical weapons. The latter are being destroyed under international supervision in Russia, the United States and other countries.


Most governments do not think nuclear power and nuclear weapons are inextricably linked – like Siamese twins. Even today the powers that are negotiating with Iranand that are concerned that Iran may wish to develop a nuclear weapon, declare that they would be ready to assist Iran in a further development of nuclear power, provided however, that Iran would be willing to forego its program for the enrichment of uranium.

Most governments thus act on the premise that states can have nuclear power without having nuclear weapons. Indeed, most states which have nuclear power do not have the weapons: Sweden, Finland, Germany are examples.

A phasing out of nuclear power in some or all states would not lead to the scrapping of a single nuclear bomb.

States can have nuclear weapons without nuclear power though it is not common today. Israelis a case in point. It has no nuclear power but is assessed to have some 200 nuclear warheads. For a long time China had only the weapons. Indeed, most nuclear weapons states, including the US, had weapons before they had power.

But how can we have confidence that states do not hide nuclear weapons programs in a nuclear power program? Iraq and North Korea misled the world andIran is suspected of doing the same. Perhaps we risk waking up to more unpleasant surprises, if nuclear power were to expand?

Let us first note that the major part of any expansion of nuclear power would occur in countries that already have nuclear power – the US, UK, China, Russia, Japan, India etc, Whether the US would have 200 nuclear power plants rather than 100 or Sweden would have 20 instead of 10 would hardly risk increasing the number of nuclear weapons in the world.


The concerns are not, in fact, so much about the number of nuclear power plants as about installations producing enriched uranium -- fissile material that can be used as fuel if the enriched to 4 % but also as cores in nuclear warheads if enriched to some 85 or more %.

Such fuel cycle installations exist today in all nuclear weapon states and in a few others: Argentina and Brazil, Germany and the Netherlands, Japan, South Africa and North Korea. And one enrichment plant is under development in Iran.

It is the plutonium plant in North Korea and the enrichment program Iran that have prompted a lively international debate about possible schemes discouraging or stopping the construction of further fuel cycle plants.

One such scheme – GNEP – has been advanced by the US Department of Energy. Under this proposal only a fewfuel cycle states’ would enrich uranium and they would lease – rather than sell – fuel to other states. They would take back the spent fuel and reprocess it in a new technique that would not result in separated plutonium but in a mixture of fissile material that would be difficult to divert to weapons. With the addition of some actinides – it could be used in a new type of fast reactors, which only the fuel cycle states would run.

Only the other day several states rallied to support this scheme at a meeting in Vienna. It would bring important innovations but it is also somewhat distant and speculative. Returning spent nuclear fuel to the US would remove the risk that it could be reprocessed into plutonium abroad and it would also have an attraction for states participating that they would not have to worry about the management of spent fuel and waste disposal.

We might note that the Soviet Union took back uranium fuel that had been spent in Soviet made power reactors in Eastern Europe. No doubt in part to prevent the risk of it being used for plutonium production.  However, the US congress and public is generally wary of nuclear waste. Would there be assent to a return to the US of spent fuel? We do not know.

We might further note that the scheme envisages reprocessing in the US. This marks an abandonment of President Carter’s policy to renounce any reprocessing of civilian spent fuel and a renewed acceptance of breeder reactors. It fits well into a world in which such reactors may be needed to better utilize the energy contents of uranium fuel. However, it is well understood that neither reprocessing nor breeder reactors would be economic today. This underlines that the scheme, though interesting, is somewhat hypothetical.

Some non-nuclear weapon states might also worry that the scheme might lead to a kind of a nuclear cartel – a nuclear OPEC.

Indeed, most schemes that seek to discourage further states from developing fuel cycle facilities risk running into the objection that they confirm and deepen the division between a class of states that is allowed to have advanced technologies and nuclear weapons and all other states. States like Australia, Canada, South Africa, Brazil and others that have much uranium on their territory may be particularly unlikely to renounce the option of refining products from their mines.

Whatever be the fate of the various schemes now under discussion they are most unlikely to provide timely solutions to the acute cases of fuel cycle installations in North Korea and Iran. This is regrettable because the two cases, in my view, do illustrate the need to discourage enrichment and reprocessing at least in some sensitive areas and ways out.


Already in the 1992 Denuclearization Declaration adopted by North and South Korea it was expressly stipulated that neither state could have enrichment or reprocessing. Clearly the mutual lack of confidence between the two could lead to suspicions and tensions, if either of them produced enriched uranium or plutonium. Even now it seems understood in the six power talks in Beijing that this agreement from 1992 will remain. Evidently, it provides a more important restriction on South Korea that has now 20 power reactors that require enriched uranium fuel than it does on North Korea that has none. The arrangement will have to be balanced by some international guarantee of supply of fuel.

In the report of the WMD commission that I chaired the arrangement contemplated for Korea is cited as a possible model for another area in which states would be intensely suspicious about any fuel cycle installations: the Middle East. We have recently heard threats of military action against Iran unless the country suspends its program for uranium enrichment. The suspicion is intense that Iran might come to use such enrichment program to make nuclear weapons.

A clearing up might be possible of past question marks that have been identified and this is evidently the aim of the understanding recently reached by the DG of the IAEA with Iran.

However, while highly professional and intrusive safeguards verification is valuable to show and explain what the situation on the ground, it is unlikely to prove the negative – that something does not exist.  Above all safeguards verification can hardly prove the absence of weapons intentions and even if it were possible to do so, the absence of any such intentions today, would not preclude that intentions could change a year or two from now.

With factory scale enrichment installations in place the path to weapons would be shorter than if there had been no such installations. This is the reason why the Security Council has not been content to ask explanations but requested a suspension of the enrichment program that is not per se illegal.

The WMD commission raises the question whether an arrangement might be possible under which all states in the Middle East -- including Iran and Israel, Egypt and the Gulf states that have declared that they will develop nuclear power – would renounce all enrichment and reprocessing for a prolonged period of time. Israel would retain its weapons until – in a next phase –  a zone free from such weapons were negotiated, but the country would have to accept a verified stop on any further production of plutonium. As in the case of Korea assurances of supply of uranium fuel for power reactors would have to be given by outside states to all participants.

RISK for NUCLEAR PROLIFERATION apart from Korea and Iran

I said a little while ago that the genie is out of the bottle. While any state wishing to develop nuclear weapons would undoubtedly wish to get help from the outside – as we have seen that Iraq, Libya and others have received – such help may not be indispensable. With sufficient time, readiness to spend considerable resources and a certain level of technical infrastructure many states would be able to produce nuclear weapons.  How can we minimize the risk that they do it?

First, we should note that a capability – technical and other -- to develop nuclear weapons does not equal doing it. Statements have been made to the effect that there might be 30 to 40 ‘virtual’ nuclear weapon states. Such a number, which would include countries like the Nordic states, Austria, Switzerland, is misleading. To develop nuclear weapons not only a capability but also a political will is needed and states like those I have mentioned have long ago concluded that regardless of their capability they will not acquire nuclear weapons. They should rather be termed ‘virtuous non-nuclear weapon states’.

Which states then might be tempted at the present juncture to develop nuclear weapons? A closer look at the nuclear technical and scientific activities around the world does not really suggest that any countries can be added to the old ‘suspects’ – Iraq, Libya, North Korea and Iran. Of these Iraq and Libya have been taken care of – in different ways –  and intense negotiations are under way with both North Korea and Iran.

If these negotiations can be ended successfully – admittedly a big if – no strong immediate incentives would remain for any other states to develop nuclear weapons. However, if these two states were to continue moving on a weapons path there could be dangerous domino effects. In North East Asia a pressure for nuclear weapons in Japan and South Korea would drastically and quickly sharpen tensions. In the Middle East the already tense relations would be exacerbated but no state in the region is sufficiently technically advanced to develop nuclear weapons quickly.


  • The four cases I have mentioned – Iraq, Libya, North Korea and Iran – have prompted many comments that the Non Proliferation Treaty of 1968 may collapse. This, in the view of the WMD commission, is much too alarmist a view. The world is not milling with would be proliferators.
  • Many technically advanced statesare parties to defense alliances that provide them with nuclear umbrellas. Other such states – like Sweden – have concluded long ago that their security would not be improved but perhaps impaired by the possession of nuclear weapons. A large number of states are still simply not at the technical level that they could contemplate such weapons.
  • Yet, even though the NPT is not threatened by collapse it is clearly under some strain. I shall explain why.
  • The Treaty of 1968 had the ambition to lead to a world without nuclear weapons.
  • The non-nuclear weapon states of the world were invited to commit themselves not to acquire nuclear weapons, and
  • The then 5 nuclear weapon states were invited to commit themselves to negotiate toward nuclear disarmament.
  • If all had adhered and all had implemented their commitments we would now live in a nuclear weapon free world. But we live I a world of some 27.000 nuclear weapons and 9 nuclear weapon states. This is a failure that can no longer be excused by a Cold War. There are no significant conflicts between the five great powers about borders, territory or ideology.                      
  • In several respects the NPT has been a great success:
  • Almost all NNWS have adhered to the treaty and it is of special value that Ukraine, Byelorussia and Kazakhstan joined and transferred their nuclear weapons to Russia.
  • Further that South Africa dismantled its nuclear weapons and joined NPT.
  • In other respects there are more failures:
  • The DPRK, Iraq and Libya were state parties that violated the treaty. Iran– despite claims to the contrary – is suspected by several states to have the intention to abandon its commitment.
  • It is also negative that three states never adhered to the treatyIndia, Israel and Pakistan – and that they all developed nuclear weapons.

It is equally if not more dismaying that the five NWS since a number of years have not taken their commitment to negotiate toward nuclear disarmament seriously:

The NPT 2005 Review Conference ended in acrimony, many non-nuclear states feeling cheated by the nuclear weapon states. The UN Summit the same year was unable to adopt a single line about arms control and disarmament. And the Conference on disarmament has not been able to adopt a work program for about a decade.

Kofi Annan warned over a year ago that the world was sleep walking into new arms races. By today we should have woken up.

    • The UK has decided on a continuation of the nuclear Trident submarine program.
    • The US administration proposes to develop a new standard nuclear weapon.
    • Chinahas shot down a weather satellite of its own, demonstrating a capability for military action in space
    • Russiahas further developed nuclear missiles and stated that it will withdraw from the agreement on conventional armed forces in Europe. 
    • World military expenses amounted in 2006 to about 1.3 trillion dollars – of which about half fell on the US budget.

Clearly there is not just one ‘inconvenient truth’ -- about global warming. There is ‘another inconvenient truth’, namely, about arms races between nuclear weapon statesand about the long term risk for another wave of proliferation, if the great powers do not begin serious negotiations toward disarmament.

  • The WMD Commission that I chaired urges a revival of disarmament, notably
  • that the US Senate reconsider its rejection of the comprehensive test ban treaty (CTBT). No other measure could send a stronger signal in the international community that disarmament is moved back on the global agenda.
  • that a US proposal for a treaty prohibiting the production of enriched uranium and plutonium for weapons (FMCT) should be moved into the CD conference room,
  • that the US and Russia take initiative to a reduction (not just redeployment) of nuclear weapons.
  • that nuclear weapons should be taken off hair trigger alert,
  • that nuclear weapons be removed from Western Europe and Western Russia to reduce tension, and
  • that controls and export controls be strengthened on radioactive and fissionable material to make it harder for terrorists to acquire such material .

Prospects for a reduction of the risks posed by nuclear weapons?

The most encouraging sign is that a group of US elder statesmen –  Shulz, Kissinger, Bill Perry and Sam Nunn – have published an article entitledNuclear madness’. They urge the US to take an initiative with the other nuclear weapon states stepwise to get to nuclear disarmament. Today, they say, nuclear deterrence is not needed between the big powers and the continued arsenals may be an incentive for others, including terrorists, to acquire such weapons. It is too early to know what impact the article may have. Clearly, the excessive faith in military power is on retreat in Washington.

Let me conclude by saying that the WMDC stressed that when we want to prevent proliferation or retention of nuclear weapons the best approach is one that make countries feel that they do not need nuclear weapons for their security.

Foreign, security and economic policies may be the most important avenue to reduce the risk posed by nuclear weapons. Policies of cooperation should not only be possible but indispensable: States find it necessary to cooperate to protect the global environment, to manage the global economy and to stop viruses. Why not also cooperate to stop shooting at each other?

  • The window that opened at the end of the Cold War has been allowed to hang flapping in the wind. It is high time that it be fully opened and leads to a cooperative security order which eliminates the risks posed by nuclear weapons.