Disarmament Diplomacy

US Department of Energy Press Release: Subcritical Experiments

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"At the United Nations last year, as the first world leader to sign the Comprehensive Test Ban Treaty, President Clinton firmly committed the United States to the pursuit of a world free of nuclear testing, observing that this treaty was the culmination of the work of American Presidents - both Republican and Democrat - over the past four decades.

When the President made the decision to pursue a zero yield Comprehensive Test Ban Treaty, he stated that, even in the absence of nuclear testing, we would maintain 'strategic nuclear forces sufficient to deter any future hostile foreign leadership from acting against the interests of the United States.' The President also declared that the maintenance of a safe and reliable nuclear weapons stockpile is a necessary condition for US entry into a Comprehensive Test Ban Treaty.

Maintenance of a safe and reliable nuclear weapons stockpile is the direct responsibility of the Department of Energy (DOE). To this end, we are announcing today a schedule for subcritical experiments - an essential component of the Department's program for ensuring the safety and reliability of the stockpile. The first in a series of these experiments is now scheduled for June 1997, with a second similar experiment to follow sometime this fall.

Over many decades, a group of distinguished scientists known as the JASONs has provided the US Government independent, expert analyses in defense and arms control issues. At the request of the Department of Energy, the JASONs conducted a review of the designs of the Department's first two subcritical experiments. In a January 1997 letter transmitting this review to Acting Secretary of Energy Charles Curtis, the JASONs concluded that 'these particular experiments will add valuable scientific information to our database relevant to the performance of our nuclear weapons, and that there is no conceivable scenario in which these experiments lead to criticality.' Yesterday, the JASONs formally released their report.

Subcritical experiments are essential to our commitments to a world free of nuclear testing and a reliable nuclear deterrent and are fully consistent with the CTBT. In addition, these experiments complement other elements of DOE's Stockpile Stewardship and Management program such as the National Ignition Facility and the Accelerated Strategic Computing Initiative - additional tools which will help supply the confidence in stockpile safety and reliability the President has required in order to support the CTBT.

The Comprehensive Test Ban Treaty represents an advancement of peace and security for the American people. It is a clear demarcation between the Cold War Era and the post-Cold War world: between a runaway arms race, fear of nuclear proliferation and concern about environmental degradation - and increased stability, enhanced security and ongoing international cooperation. The Department of Energy is proud of its contribution toward these important national and international goals."

Editor's note: the press release was accompanied by a fact sheet (R-97-024(a)), 'Announcement of Schedule for Subcritical Experiments: Questions and Answers,' reproduced below in full:

"Q. What are Subcritical Experiments?

A. Subcritical experiments are an essential component of the Department's science-based stockpile stewardship program designed to maintain a safe and reliable nuclear weapons stockpile under a test ban. These experiments use high explosives and nuclear weapon materials (including special nuclear materials like plutonium) to gain important data that will be used to maintain the stockpile without conducting nuclear explosions banned by the Comprehensive Test Ban Treaty. The Secretary of Energy today announced the schedule for the conduct of these experiments.

Q. Are subcritical experiments consistent with the Comprehensive Test Ban Treaty (CTBT)?

A. Subcritical experiments are fully consistent with the terms of the Comprehensive Test Ban Treaty (CTBT), signed by President Clinton last September at the United Nations. The treaty bans 'any nuclear weapon test explosion or any other nuclear explosion'. Subcritical experiments, on the other hand, are configured such that no self-sustaining nuclear chain reaction can occur even though special nuclear materials will be present. In other words, the configuration of each experiment guarantees that no nuclear explosion prohibited by the treaty can result.

Q. How does the conduct of subcritical experiments support the Comprehensive Test Ban Treaty?

A. Subcritical experiments provide the United States with the means to gain important data needed to maintain the stockpile without conducting nuclear explosions. In 1993, President Clinton directed the Department of Energy to develop a science-based stockpile stewardship program to ensure that the US stockpile would remain safe and reliable under a test ban regime. In August, 1995, President Clinton elaborated six safeguards which would condition US support for the Comprehensive Test Ban Treaty. Subcritical experiments directly support three of those safeguards, including:

* Safeguard A: 'the conduct of a Science-Based Stockpile Stewardship program...including the conduct of a broad range of effective and continuing experimental programs,'

* Safeguard B: 'the maintenance of modern nuclear laboratory facilities and programs in theoretical and exploratory nuclear technology which will attract, retain, and ensure the continued application of our human scientific resources...,' and

* Safeguard C: 'the maintenance of the basic capability to resume nuclear test activities prohibited by the CTBT should the United States cease to be bound to adhere to this treaty.'

Thus, the conduct of subcritical experiments, along with other stockpile stewardship and management activities, will allow the United States to abide by the provisions of the CTBT not to conduct nuclear test explosions and will greatly reduce the likelihood that Safeguard F (which involves US withdrawal from the treaty due to a lack of confidence in the safety or reliability of a critical nuclear weapon type) will ever need to be invoked.

Q. How are these experiments important for our nation's stockpile?

A. These experiments will contribute to the Department of Energy's national defense-related mission in two important ways:

Science Based Stockpile Stewardship: In order to maintain the safety and reliability of the Nation's nuclear weapon stockpile without nuclear testing, the Department of Energy (DOE) has developed, at the President's direction, a 'Science-Based Stockpile Stewardship (SBSS)' program. The SBSS program will utilize advanced computer simulations and experimental programs on which the assessment of the safety and performance of the Nation's nuclear weapon stockpile will be based. Confidence in these assessments can be significantly improved with data from subcritical experiments. Specifically, such experiments will provide needed data on the behavior of weapon materials and components, as well as the effects of remanufacturing techniques, aged materials, and other technical issues.

Nuclear Test Readiness: By exercising a number of operations similar to nuclear testing (since these experiments do involve high explosive, special nuclear materials and will be done underground at the Nevada Test Site), the experiments will effectively maintain the Department's nuclear test readiness capabilities. This activity assists in implementing the President's Comprehensive Test Ban Treaty Safeguard, announced August 11, 1995.

Q. Why is the Department conducting subcritical experiments underground?

A. By conducting subcritical experiments in an already existing underground complex on the Nevada Test Site (NTS), public and NTS worker safety will be best ensured, environmental impacts will be minimized, and the cost to the taxpayer will be reduced since the development of an above-ground reusable chamber would take years to design, build and certify for safety.

Q. What transparency measures is the Department planning with respect to subcritical experiments?

A. In the interest of transparency, the Department is taking several actions to assure the public that these experiments will indeed be subcritical. The first two experiments have been reviewed by technical experts at the Los Alamos and Lawrence Livermore National Laboratories to assure they will remain subcritical (consistent with the CTBT) and that all operations will adhere to safety and environmental laws and regulations. Each subsequent experiment will be reviewed in a similar fashion.

In addition, a review of the designs of the first two planned subcritical experiments has been conducted by the JASONs, an independent group of eminently qualified scientists. They concluded that the experiments will add valuable scientific information to our database relevant to the performance of our nuclear weapons, and that there is no conceivable scenario in which these experiments lead to criticality. A report written by the JASON subgroup was released yesterday on this subject and the JASONs will have access to experimental results.

Subsequent subcritical experiments will be assessed by a similar independent review process.

Q. How can the public obtain more information about these experiments?

A. The Department has prepared written and visual materials on these experiments that are available to the public. We understand that such information will be helpful in informing members of the public that these experiments will be conducted in full compliance with environmental, safety, and policy guidelines. Information is available which describes, in general terms, the underground experiment complex and design, the objectives and nature of the experiments to be conducted there, relevant operational considerations, and the procedures used to assure their compliance with safety and policy requirements. DOE/HQ Public Information can be reached at 202-586-5575."

© 1998 The Acronym Institute.

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