ERRORS in rebuttal to "Pandora's Promise"

[kristopher]

63. More citations on the point of plutonium for weapons

Global stocks of plutonium
Plutonium was first produced in significant amounts as part of the Manhattan project, set up by the United States during the Second World War to manufacture nuclear weapons. The bomb dropped on Nagasaki was a plutonium bomb.

Most military production of plutonium in the established nuclear-weapon powers (China, France, Russia, the UK, and the USA) has halted. But amounts of plutonium in commercial plutonium programmes are increasing dramatically. In France, Japan, Russia, and the UK stocks of civil plutonium will increase by as much as 125 tonnes by 2015, equal to half of all the plutonium produced by the nuclear-weapon states for use in nuclear weapons during the Cold War. Stocks of civil plutonium have now (mid-2005) reached 205 tonnes, rivalling the 250 tonnes in military stocks. In the next ten years, global stocks of civil plutonium will total about 330 tonnes (1).

Currently, twelve countries have stocks of civil plutonium. The UK has a stock of about 71 tonnes; France has a stock of about 46 tonnes; Japan has about 39 tonnes; Russia has about 37 tonnes; the USA has about 5 tonnes; Belgium has about 4 tonnes; Sweden has about 0.83 tonnes; Spain has about 0.63; Switzerland has about 0.6 tonnes; India has about 0.5 tonnes; and the Netherlands has about 0.2 tonnes. France, Russia, Japan, and the UK own about 94 per cent of the world’s civil plutonium. (2)

Types of plutonium
There are various grades of plutonium, each with different isotopic compositions depending on the way in which the reactor producing it is operated. Plutonium produced in civil nuclear-power reactors operated for the most economical production of electricity is called reactor-grade plutonium. Plutonium produced in military plutonium production reactors, specifically for use in nuclear weapons, is called weapon-grade plutonium. Weapon-grade plutonium typically contains 93 per cent of plutonium-239 and about 7 per cent of plutonium-240. Reactor-grade plutonium typically contains about 60 per cent plutonium-239, about 20 per cent of plutonium- 240.

Usability of reactor-grade plutonium in nuclear weapons
It is now generally recognised that nuclear weapons can be made from reactor-grade plutonium although those made using weapon-grade plutonium are somewhat more effective (3). Official recognition that reactor-grade plutonium can be used to fabricate nuclear weapons was given by, for example, Lord Gilbert in the UK (4). It is for this reason that reactor-grade plutonium is normally subjected to national and international security and safeguards measures in an effort to detect and deter its diversion or acquisition by countries or terrorist groups.

Weapon designers prefer weapon-grade to reactor-grade plutonium mainly because of the spontaneous fission that occurs in plutonium-240. If a nuclear weapon is made from reactor-grade plutonium, spontaneous fission occurring in the core of the weapon made causes it to heat up. To avoid the distortion of the core by this heat, measures must be taken to dissipate some it, although this is not a difficult problem.

Nevertheless, some official statements still imply that reactor-grade plutonium cannot be used in nuclear weapons or nuclear explosive devices. For example, Ryukichi Imai, former Japanese Ambassador for Non-Proliferation, stated that:

“Reactor-grade plutonium is of a nature quite different from what goes into the making of weapons . . . Whatever the details of this plutonium, it is quite unfit to make a bomb.”

(5)

But, as Robert Seldon of Lawrence Livermore Laboratory explains:

“All plutonium can be used directly in nuclear explosives. The concept of . . . plutonium which is not suitable for explosives is fallacious. A high content of the plutonium 240 isotope (reactor-grade plutonium) is a complication, but not a preventative.” (6)

The former Director General of the International Atomic Energy Agency (IAEA), Hans Blix, stressed that the IAEA:

“considers high burn-up reactor-grade plutonium and in general plutonium of any isotopic composition...to be capable of use in a nuclear explosive device. There is no debate on the matter in the Agency’s Department of Safeguards.” (7)

And at a conference in Vienna in June 1997, Matthew Bunn, who chaired the US National Academy of Sciences analysis of options for the disposal of plutonium removed from nuclear weapons, made a crucially important statement based on recently declassified material “of unprecedented detail on this subject”:

“For an unsophisticated proliferator, making a crude bomb with a reliable, assured yield of a kiloton or more -- and hence a destructive radius about one- third to one-half that of the Hiroshima bomb -- from reactor-grade plutonium would require no more sophistication than making a bomb from weapon- grade plutonium. And major weapon states like the United States and Russia could, if they chose to do so, make bombs with reactor-grade plutonium with yield, weight, and reliability characteristics similar to those made from weapon-grade plutonium. That they have not chosen to do so in the past has to do with convenience and a desire to avoid radiation doses to workers and military personnel, not the difficulty of accomplishing the job. Indeed, one Russian weapon-designer who has focused on this issue in detail criticized the information declassified by the US Department of Energy for failing to point out that in some respects if would actually be easier for an unsophisticated proliferator to make a bomb from reactor-grade plutonium (as no neutron generator would be required).” (8)

That reactor-grade plutonium can be used to fabricate nuclear weapons was proved by the British who exploded such a device in 1956 (9) and by the Americans who exploded at least one such device in the 1960s. This is why reactor-grade plutonium is also known as weapon-usable plutonium.

The critical mass of a fissile material, such as plutonium, is the minimum mass necessary to sustain a nuclear-fission chain reaction and, therefore, to produce a nuclear explosion. No explosion occurs in a mass of plutonium below the critical mass. If the mass is more than critical (i.e., it is super-critical) the fission chain reaction is sustained for as long as the mass of plutonium remains super-critical. The critical mass of a bare sphere of reactor-grade plutonium metal is about 13 kilograms, a sphere of about six centimetres in diameter. The critical mass of a bare sphere of weapon-grade plutonium metal is about 11 kilograms. (10)

If the sphere of plutonium metal is surrounded by a shell of material, such as beryllium or uranium, neutrons that escape from the sphere without producing a fission event are reflected back into the sphere. A reflector, therefore, reduces the critical mass. The reduction can be considerable. A thick reflector will reduce the critical mass by a factor of two or more. Modern nuclear weapons contain less than 4 kilograms of weapon-grade plutonium.

OXFORD RESEARCH GROUP
The Proliferation Consequences of Global Stocks of Separated Civil Plutonium
Dr. Frank Barnaby June 2005
http://www.oxfordresearchgroup.org.uk/sites/default/files/plutonium.pdf

1. Soaring stocks of weapons-usable plutonium demand international support of Comprehensive Fissile Materials Treaty, Greenpeace International, Press Release, Washington DC, 12 May 2004.
2. Shaun Burnie, Paper prepared for the NPT Review Conference, New York, May 2004.
3. Mark, J. Carson, Reactor-Grade Plutonium Explosive Properties, Nuclear Control Institute, Washington D.C., August 1990.
4. Gilbert, Lord, Minister of State, Ministry of Defence, House of Lords, Hansard, 24 July 1997, Col WA 184.
5. Imai, R., Plutonium, No. 3, October 1994.
6. Selden, R. W., Reactor Plutonium and Nuclear Explosives, Lawrence Livermore Laboratory, California, 1976.
7. Blix, H., Letter to the Nuclear Control Institute, Washington DC, 1990. 8. Bunn, M, paper at International Atomic Energy Agency Conference, June 1997.
9. Arnold, L., A Very Special Relationship: British Atomic Weapon Tests, Chapter 4, HMSO, London, 1987.
10. Lovins, A. B., 1990, Nuclear Weapons and Power-Reactor Plutonium, Nature, London 283, 817-823 and typographical corrections, 284, 190.
11. The Environment Council, report of the Plutonium Working Group, March 2003 (http://www.the-environment-council.org.uk/docs/PuWG_Report_Mar_03.pdf)