What is SUBCRITICAL Nuclear EXPERIMENTS?

What is SUBCRITICAL EXPERIMENTS?
Subcritical Nuclear Weapons Experiments-by: Physicians for Social Responsibility
March 20, 1998
Based on "Subcritical Experiments After the Test Ban Treaty" by Daryl Kimball, February 3, 1997.

The United States government is currently conducting a series of "subcritical" nuclear weapons experiments underground at the Nevada Test Site, 85 miles northwest of Las Vegas. A subcritical experiment is a nuclear weapons experiment in which chemical high explosives blow up special nuclear materials -- including plutonium-239, a main ingredient of nuclear weapons -- ostensibly so scientists can better understand how nuclear weapons age.

Subcritical nuclear experiments differ from traditional nuclear weapons tests in that they are designed to not reach criticality, in other words to not sustain a nuclear chain reaction. Because of this, subcriticals are not explicitly banned under the Comprehensive Test Ban Treaty, the international agreement which would prohibit all nuclear explosions with yields greater than zero.

The subcriticals are one component of the "Stockpile Stewardship" program, a $60 billion (over 13 years) program initiated by the U.S. Department of Energy to upgrade old nuclear weapons facilities and build new ones for the purpose of maintaining the "safety" and Areliability" of the enduring nuclear stockpile in the absence of underground nuclear testing. Each subcritical experiment costs about $20 million in direct costs, plus the additional cost of maintaining the Nevada Test Site.

PSR concludes that the stated rationale for undertaking the subcritical nuclear experiments is not justified. The Department of Energy has not demonstrated that the subcriticals are essential for stockpile safety and reliability. Nor has the U.S. government thoroughly evaluated the impact of the subcriticals on nuclear arms control and proliferation. PSR recommends that the subcriticals be canceled and the Nevada Test Site closed to further nuclear weapons-related activities.

Background

In October 1995, the Department of Energy (DOE) announced its original plan to conduct a series of six subcritical nuclear underground explosions in 1996 and 1997. The subcritical tests were originally scheduled to take place before negotiations on the Comprehensive Nuclear Test Ban Treaty were concluded, but the experiments were postponed to allow further environmental impact analysis, and out of concern that they would impede Treaty negotiations.

The first two subcritical nuclear weapons experiments were conducted in 1997. The first, code-named "Rebound," was conducted on July 2. In it, chemical explosives blew up 3.3 pounds of plutonium. The second, code-named "Holog," was conducted on September 18 and involved two simultaneous explosions, the first with 77 grams of plutonium and 50 grams of high explosives, and the second with 50 grams of plutonium and 50 grams of high explosives. Both tests took place in an underground facility at the Nevada Test Site.

According to the DOE, the first two tests provided additional data on the behavior of plutonium in a "strongly-shocked" state -- data that is said to be needed for improving supercomputer modeling of nuclear weapon performance and assessing changes in weapon remanufacture techniques and materials. The first two subcritical experiments did not involve nuclear warheads, warhead prototypes, or "weapons configurations," but DOE officials have not ruled out the possibility of conducting experiments involving "weapons configurations," which could result in "hydronuclear" explosions. In the past, such "hydronuclear" tests resulted in barely critical configurations that released a small amount of fission energy.

Four more subcriticals are scheduled for 1998, and more in later years. DOE has announed that the next subcritical test, code-named "Stagecoach," will be conducted on March 25, 1998. It will take place at the Nevada Test Site's U1a Complex, an underground laboratory approximately 960 feet beneath the surface. According to the DOE, Stagecoach is a Los Alamos National Laboratory-sponsored experiment whose primary objective will be to obtain physics information on plutonium samples of varying ages. Stagecoach will be comprised of 5 simultaneous blasts involving 255 pounds of chemical high explosives which will generate high pressures applied to 2 pounds 2 ounces of weapons plutonium.

Rationale for Experiments Unjustified

The DOE has been directed by the President and Congress -- through documents such as the 1994 Nuclear Posture Review, the National Defense Authorization Act of 1994, and several publicly announced Presidential Decision Directives -- to maintain the safety and reliability of U.S. nuclear arsenal in the absence of nuclear testing and without new-design weapon production.

The DOE claims that the "Stockpile Stewardship" (SS) program is needed to meet these directives, and that the subcritical experiments would specifically be used to: (1) improve the knowledge of the dynamic properties of aged nuclear materials (e.g., plutonium) in order to assess the effects of new manufacturing techniques on weapons performance; (2) help maintain the capabilities of the Nevada Test Site and support nuclear test "readiness"; and (3) provide data to support the "Stockpile Stewardship" program.

However, the DOE is extending its directives beyond what is technically required. To illustrate:

* The DOE has not established that there is a need to conduct the subcritical experiments. There has been no independent technical review in support of their scientific importance, conduct, timing or site selection. In June 1997, DOE commissioned the JASONs, an independent group of scientists, to confirm that the first two tests were designed to be Asubcritical." The group confirmed that, but also added that Athere is no claim that the data from these experiments are needed immediately as part of the Science Based Stockpile Stewardship Program in order to retain confidence in the reliability and performance of the U.S. stockpile..." The JASONs report also recommended that Aan independent review process should also address the scientific importance and cost-effectiveness of proposed subcritical experiments." No such review has been undertaken to date.

* The DOE has not shown that the subcritical experiments are required to maintain a reliable and safe nuclear stockpile. There is no evidence to date to suggest that plutonium aging has degraded the expected performance of the weapons designs used in the current U.S. nuclear arsenal. In fact, in May 1996, the Institute for Energy and Environmental Research released a report which showed that there has not been a single aging-related nuclear safety problem in the U.S. arsenal and that nuclear safety problems arose in the context of warhead design, not aging.

* The true purpose of the SS program is questionable. A once-classified document known as the DOE AGreen Book," obtained in 1997 through the discovery process of NRDC v. Pena, indicates that the real purpose of the SS program is the design and development of new weapons, rather than the maintenance of the current weapons stockpile. Not only is this against U.S. policy, but focusing the program on designing and developing new weapons is likely to actually decrease confidence in the reliability of the U.S. nuclear arsenal.

* The U.S. government has not thoroughly evaluated the nuclear arms control and non-proliferation impacts of conducting subcritical nuclear experiments. By moving forward with the subcriticals, the U.S. is likely increasing the risk of proliferation by condoning/encouraging such experiments by other countries and by usurping resources from programs and activities better able to maintain a truly safe nuclear arsenal.

* U.S. lawmakers are raising concerns about the subcriticals and the SS program. In June 1997, 44 members of the U.S. House of Representatives, led by Rep. Cynthia McKinney of Georgia, sent a letter to President Clinton urging him to cancel the subcritical experiments. In addition, last month 33 members, led by Rep. Lynn Woolsey of California, urged the President to support cuts to the DOE weapons program budget and to help move the U.S. toward a more sensible approach to nuclear weapons stewardship.

Negative Impacts on the Comprehensive Test Ban Treaty and Non-Proliferation

It is generally acknowledged that the Comprehensive Test Ban Treaty (CTBT), which prohibits "any nuclear weapon test explosion or any other nuclear explosion," does not prohibit subcritical nuclear experiments because the experiments are not designed to produce a self-sustaining nuclear chain reaction. However, conducting the subcritical experiments could have a serious negative impact on U.S. nuclear non-proliferation goals, make verification of the nuclear test ban treaty difficult, and complicate the test ban treaty's entry-into-force. Consider these points:

* Because the CTBT's verification and on-site inspection system is not yet fully in place, subcritical experiments complicate the ability to verify violations of the CTBT. In other words, until the CTBT's verification system is in place, it will be difficult to determine if such experiments are truly Asubcritical." This point is illustrated by the August 1997 Russian seismic event which generated great suspicion in the U.S. and elsewhere about whether the event was a nuclear test, subcritical experiment or a small earthquake. Weeks later, the U.S. government determined it to be the latter.

* By conducting the subcriticals, the U.S. could set back the CTBT's formal entry-into-force, which requires ratification by 44 named, nuclear weapons-capable states, including India, Pakistan and North Korea which have not yet signed the treaty. India, reacting to the first subcritical test, stated that its opposition to the CTBT was due to its Aloopholes ... exploited by some countries to continue their testing activity, using more sophisticated and advance techniques." Continuing the subcriticals is hardening the position of several states that are concerned that the U.S. (and other declared weapons states) will continue nuclear weapons development through laboratory-based programs and activities such as subcritical experiments.

* International opposition to the subcriticals is mounting. Governments which have publicly expressed opposition to the subcritical experiments include those of China, India, Iran, Libya, Pakistan, and Norway. Last month, the European Parliament passed a resolution which calls upon the U.S. government to Ahalt the series of sub-critical tests and [for] all governments to refrain from carrying out such tests." The resolution also calls for increased transparency at the test sites and an official declaration from the U.S. government stating that the subcriticals are in no way part of a new nuclear weapons design program.

* Continuing nuclear testing operations at underground test sites contravenes the spirit of the CTBT which Aseeks to achieve the discontinuance of all nuclear weapon test explosions and all other nuclear explosions for all time," and the hope of the vast majority of nations and citizens worldwide that the nuclear test sites will be closed. The subcriticals instead serve to reinforce concerns, domestically and internationally, that the U.S. is not only interested in maintaining existing arsenals but also wants to maintain an active Nevada Test Site for resuming nuclear tests and the capacity for new weapons design and development.

An Alternative

The U.S. can maintain the nuclear arsenal's safety and reliability without subcritical nuclear weapons experiments and the elaborate AStockpile Stewardship" program. Retired U.S. nuclear weapons designer Ray Kidder advocates that the DOE instead undertake a Apassive curatorship" program which is less expensive and of much smaller dimensions, and which supports U.S. goals of nuclear non-proliferation and nuclear arms reduction. This alternative would involve monitoring, replacement and remanufacture of warhead components according to the original designs. Plutonium pits would be replaced with existing pits in storage and parts would be remanufactured according to the original designs at far less cost.

Conclusion

The U.S. should immediately discontinue the subcritical nuclear experiments. The experiments send a message to the world that the U.S. is more interested in advancing nuclear weapons expertise than in advancing non-proliferation and disarmament goals. The U.S. should lead the world in ending all nuclear testing and seek an agreement with Russia and China to permanently close the remaining nuclear testing sites.

Should the U.S. refuse to immediately abandon the ill-conceived subcritical experiments, it should at least: a) arrange for a thorough, independent, public review to determine whether the subcritical experiments are technically necessary to address warhead safety and reliability problems known to exist in the current arsenal; b) conduct a thorough, public evaluation of the non-proliferation and treaty implications of conducting such activities, particularly CTBT entry-into-force; and c) develop a transparency or verification plan that is capable of demonstrating to the international community that the U.S. is not violating its legal obligations as a CTBT signatory. Because subcritical experiments are setting a new and destabilizing precedent that other nations might choose to emulate, it is in the U.S. national security interest to ensure that any such verification plan can be applied to other states that might be capable of conducting low-yield nuclear weapons experiments.



Based on "Subcritical Experiments After the Test Ban Treaty" by Daryl Kimball, February 3, 1997.

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