Disarmament Diplomacy

Issue No. 63, March - April 2002

News Review

US-UK Subcritical Test Reported

On February 14, the US and UK conducted a joint subcritical nuclear test - codenamed Vito - at the Nevada test site. Such tests - involving no nuclear chain reaction or release of nuclear material, and thus permitted under the terms of the CTBT - are routinely conducted by both the United States and Russia. According to La Tomya Glass, spokesperson for the US National Nuclear Security Administration (NNSA), Vito was the first joint US-UK test: "This is just the first opportunity that we've gotten to work directly with them on a subcritical experiment." Such cooperation is permitted under the terms of the 1958 US-UK Mutual Defence Agreement.

British participation was announced in advance of the test, in a February 12 written parliamentary answer from Under Secretary of State for Defence Dr. Lewis Moonie:

"To ensure that we continue to be confident of the safety and reliability of our nuclear weapons, it is essential to understand the properties of warhead materials such as high explosive and plutonium under a very wide range of physical conditions, and how these properties change with age. Confidence in the safety and reliability of Trident [the UK's nuclear force] is based ultimately on predictions from high fidelity numerical models run on supercomputers. The Atomic Weapons Establishment [AWE] has recently announced a major investment in a new supercomputer that will substantially upgrade its capability. However, experimental studies are still essential to validate the computational models and improve understanding of basic theory. As a continuing part of this programme the UK will shortly collaborate with the US in conducting a plutonium hydrodynamic experiment at the U1A facility in Nevada. This experiment will not produce nuclear yield and will be fully consistent with our obligations under the Comprehensive Test Ban Treaty."

Following the test, a Ministry of Defence spokesperson noted: "The United Kingdom is participating in a series of experiments involving special nuclear materials in the United States to help ensure the safety and reliability of our Trident nuclear warheads. ... Since plutonium is a relatively new element on the element chart, scientists still don't know how it ages and what happens to it..."

Subcritical tests have been criticised for violating the spirit, if not the letter, of the CTBT. On February 14, the Japan Council Against A and H Bombs delivered a letter of protest to both President Bush and Prime Minister Blair:

"As seen in the outcome of the disarmament discussions in the 56th session of the UN General Assembly, nuclear testing, whether it involves an explosion or is...subcritical, is an outright challenge to the desire of the people of the world for peace. ... We strongly urge the governments of the US and the UK to...cancel all development and test plans of nuclear weapons. We further urge you to make good on the unequivocal undertaking to accomplish the total elimination of nuclear weapons in good faith, on which governments around the world, agreed [at the NPT Review Conference] in May 2000."

In London, Nigel Chamberlain of the Campaign for Nuclear Disarmament (CND) questioned the official rationale for the test: "We believe that this test could be used to design a replacement for existing Trident warheads, clearly a breach of UK obligations under the Non-Proliferation Treaty".

Note: on February 21, the science journal Nature published an article by three Ministry of Defence scientists outlining planned upgrades to the Atomic Weapons Establishment at Aldermaston in Berkshire. According to the paper's chief author, the Ministry's Chief Scientific Adviser Keith O'Nions, quoted in The Guardian on February 22: "The Department wished to be as open as possible on this issue. This is about stockpile stewardship: assurance of the safety and reliability of warheads, specifically Trident warheads. There's no risk at all of any of our nuclear weapons going off. However, plutonium, as a metal, wasn't known to mankind until 50-odd years ago. So we only have 50 years of data. ... If you are a nuclear-weapons state - and that is a political decision which has been made in this country - it's imperative from the scientific point of view, and I think an ethical point of view, to treat the matter with the utmost seriousness and responsibility."

Reports: Written parliamentary Answer by Dr. Lewis Moonie, Hansard, February 12; US, Britain conduct Nevada nuclear experiment, Reuters, February 14; Letter to President Bush and Prime Minister Blair, Japan Council Against A and H Bombs, February 14 (http://www.twics.com/~antiatom); UK joins nuclear test in Nevada, The Guardian, February 15; Britain joins US in nuke experiment, Associated Press, February 15; Science of nuclear warheads, by Keith O'Nions, Robin Pitman & Clive Marsh, Nature 415, 853-857, February 21; Plutonium blast tests at UK site, The Guardian, February 22.