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From 1997 to 2006, the U.S. conducted 23 subcritical nuclear experiments at the Nevada Test Site. These tests, also called hydrodynamic tests, are conducted in underground tunnel chambers and involve small amounts of plutonium that are bombarded using conventional explosives to create some of the physical conditions that fissile materials (i.e. plutonium) experience at the onset of a nuclear blast.  During subcritical experiments, data is collected on the behavior of plutonium while it is subjected to tremendous shock waves, heat and extreme pressures, all environmental conditions of a nuclear explosion.  

The "subcritical" test is so named because the explosion doesn't sustain a nuclear chain reaction, but in fact these tests can produce a small fission yield.  These tests have a remote possibility of resulting in a criticality accident, as was the case at Lawrence Livermore National Laboratory in 1963. Then, a subcritical test went haywire: 'a nuclear excursion and subsequent fire took place during a subcritical experiment in a shielded vault designed for critical assembly experiments.' An excursion is a criticality accident. Wikipedia notes it 'occurs when a nuclear chain reaction accidentally occurs in fissile material, such as enriched uranium or plutonium. This releases neutron radiation which is highly dangerous to humans and causes induced radioactivity in the surroundings.' 

The root of the subcritical testing problem is that since these tests are conducted, by precedent, underground, and involve such small quantities of plutonium, it is nearly impossible to know if a country has indeed conducted a zero-yield or a very small yield nuclear blast.  There is even no way for the international community to know if any of the four countries that have, to date, conducted subcriticals - U.S., China, the U.K., and Russia - have actually conducted very small underground nuclear tests by accident or on purpose.  

Even when the CTBT goes into full effect, there is no way to know if a subcritical experiment has gone critical and resulted in a very small underground nuclear 'pop'.  The reasons are because subcriticals are:

• conducted out of sight, so there would be no flash of light detectable via satellite imagery

• involve such small amounts of plutonium, so a tiny 'pop' would be too small to produce any seismic effect

• occur at deep depths, as about 1,000 feet underground, so radioactive hot gases would likely not reach the surface and wouldn't be picked up by the radiation monitoring network of the Comprehensive Test Ban Treaty Organization (CTBTO).  

Thus, subcritical experiments naturally foster suspicion.  In August 1997, a seismic event in Russia generated suspicion in the U.S. and around the globe that Russia conducted a nuclear test or critical-subcritical experiment; the U.S. Air Force later determined that the seismic event came from the ocean and was a small earthquake.  

The CTBT would allow subcritical experiments so there is nothing stopping other nuclear weapons states from attempting to start their own subcritical testing programs.  The reason why a country would join the 'subcritical nuclear club' is that subcritical tests can help improve technical understanding of nuclear weapons.  Although the U.S. Department of Energy and other governments have stated these tests are necessary only to ensure the reliability of a nuclear stockpile (to study 'plutonium aging'), subcritical tests may help weapons designers improve their technical understanding and abilities.   A declassified document known as the DOE "Green Book," obtained in 1997 through the Freedom of Information Act, indicated that the Stockpile Stewardship program - of which 'subcrits' are a part - was not really about stewardship at all, but about new nuclear options; it stated, "In the meantime, future national policies are supported for deterrence by retaining the ability to develop new nuclear options for emergent threats." ²

Subcritical (plutonium) experiments may be assisting nuclear weapon design codes rather than ensuring 'safety' and 'reliability.' They may be aiding U.S. lab scientists at designing and developing of new weapons, not maintaining the current weapons stockpile.  

Subcritical tests may give a technical advantage to the host country, and so other countries would naturally want this advantage.  That is why in a CTBT-entry-in-force regime, there likely will be a subcritical arms race as countries scramble to begin subcritical testing programs to 'catch up' with the technical progress of other countries.  As this 'subcritical arms club' grows, international doubt and suspicion will follow not far behind.  Since these subcritical tests are conducted out of 'sight, sound and smell', and the CTBT does little to verify or police them, one country's announced subcritical experiment may be subjected to the wild imaginations of other countries.  The intentions and the technical abilities of the country conducting the subcritical test may be viewed with skepticism no matter what they say or claim.    Subcriticals are naturally untrustworthy.

The current form of the CTBT lacks any verification regime for these subcriticials, although any signatory can request that international monitors visit the country where a suspected test occurred.   But an on-site visit by international monitors may be too late by then (even if they can find the subcritical testing enclave to verify claims).  Suspicion of the deliberate conduct of, or a technical error that led to an accidental occurrence of, an underground nuclear test may force a resumption of underground nuclear testing by one country or a slew of countries.   

The CTBT is not comprehensive enough at preventing fear and distrust from spiraling towards a nuclear arms race.  Subcritical tests are currently generating suspicion and distrust worldwide; each time the U.S. conducts a subcritical test, the U.S. has flamed the fears of other countries, whose interpretation is that the U.S. is (still) testing and honing their nukes.  Their logical conclusion is that until they become nuclear, militarily they are disadvantaged.  It is unlikely that the CTBT-in-force will change anything and remedy any of the problems the CTBT is designed to solve.  

CTBT needs to ban subcritical tests.

While the prospect of an in-force CTBT is rising on the horizon, the ball still lies in the U.S.'s court.  The U.S. can declare a moratorium on subcritical tests.  Bruce Hall, a former nuclear weapons staffer for Greenpeace International, was quoted in the article 'A Subcritical Fallout' in Outook India in April 1997: "The US has the opportunity to drive the nuclear disarmament process forward, but it could also inadvertently drive the world right back into a nuclear arms race."  

Stop the nuclear testing (yes, subcritics included) once and for all

It is Idealist's firm belief that subcritical tests are an extension of the 41-year-long nuclear testing program of the United States government at the Nevada Test Site that began in 1951 and 'ended' in 1992.   First came 'Able,' the first atmospheric test in Nevada in 1951.  When all atmospheric nuclear testing was banned in 1963, the defense and energy agencies moved testing underground and conducted over 900 tremendous nuclear tests in Nevada, permanently destroying the underground areas of the Nevada Test Site and endangering the drinking water supplies of neighboring towns for perpetuity.  When Congress decided underground nuclear testing should be banned in the 1990s, these defense and energy agencies didn't want to end their underground nuclear testing.  The Defense Nuclear Agency, the predecessor to the Defense Threat Reduction Agency (DTRA), told the AP in 1993 that it thought actual underground tests should continue but would rely on nuclear simulation exercises (in 2006, DTRA tried the latest nuclear simulation dubbed Divine Strake, but failed).  However, Bill Clinton made an unwise compromise with pro-nuclear senators to make traction with other countries over the CTBT: he allowed subcritical tests, which are basically underground nuclear tests except with lesser amounts of plutonium - not enough to generate a critical reaction (as far as we know!).  Looking at the graph below, it is clear that the Nevada Test Site has had a near constant streak of nuclear tests since 1951, interrupted only by moratoriums that were only later broken.  A subcritical underground test - which Idealist places in the same category as a nuclear test - is a break of the underground testing ban and these 'nuclear' tests may signal to other CTBT signatories the U.S.'s determination to not only keep its nuclear arsenal but one day resume full-scale nuclear testing.  

This hypothesis, that subcriticals are really practice runs for full scale nuclear testing, may be the best explanation for these tests.  According to an article in the Albuquerque Journal (New Mexico) in 1997 titled' Scientists say experiments will help gauge how nuclear weapons age, but critics argue the tests will send the wrong message to the world,' the first few subcritical tests conducted in Nevada were coupled with 'practice exercises' to demonstrate that the DOE can quickly restart full-scale nuclear testing.   Also, from space (satellite imagery), preparation for a subcritical underground nuclear test appears visually not different from that for underground nuclear tests.  So, on not one but many levels, it is not difficult for independent observers to perceive that current subcritical nuclear tests by the U.S. are efforts to prime the Nevada Test Site and its lab scientists for resumption of full-scale underground nuclear testing.  If, then, the U.S. is conducting dress rehearsals for real nuclear tests via these subcriticals, then these tests are, like the below poem states, Just Shy of Nuclear and Nowhere Near Peace.  

Hiroshima's Peace Clock 

Each time any country carries out a nuclear or a subcritical test, the 'curators' of the Peace Clock Tower at the Hiroshima Peace Memorial Park reset their 'Peace Clock,' which consists of two digital clocks beneath an analog clock (showing the current time). One digital display shows the days since August 6, 1945, when the A-bomb was dropped on Hiroshima. The other counts the days since the most recent nuclear test. When a nuclear test is conducted, the number of days is reset to zero to enhance the strength of the protest from Hiroshima.

Going back to the year 2006, the Peace Clock was reset on August 30, 2006 when the U.S. conducted its subcritical nuclear test dubbed 'Unicorn' and again reset on Oct. 10, 2006 upon North Korea's nuclear test.

A subcritical test, according to the curators of the museum, is a nuclear test. And the curators are not alone in that assessment. Past subcritical tests by the U.S. have attracted severe criticism from Japanese leaders and from scores of other nation leaders across the globe. Read the scathing remarks by the European Parliament, and the Conference of Mayors for Peace at <<http://stopdivinestrake.com/subcritical.html>>.

The U.S. plans for these subcrits will reset Hiroshima's peace time-keeping. As long as these subcrit tests continue, the U.S. will add to the failure of the international community at stopping the clock from counting peace into thousands, then millions, of days. At the time of this writing the clock indicates that the number of days since the latest nuclear test is '112.' 112 days ago the North Koreans conducted their second nuclear test. This fall (of 2009) is going to be a pathetic season for this clock.  If things happen according to DOE's plan, the U.S. will reset this clock before it gets to 200, then again to zero a few weeks later, and again back to zero. And perhaps the North Koreans will be provoked, and again the clock will be set BACK TO ZERO.

The Hiroshima Peace Memorial Park curators wisely remark on their website:
'We must work toward abolishing all nuclear weapons and seek for an age of
coexistence among humankind without dependence on military force.' The Peace
Clock is their gauge of the success of that work.

Please help them succeed. Visit our action page and send a note to your senator opposing subcrits. It is easy to do. Idealist is the only U.S. organization nowadays opposing these tests and it is appreciated if you could pass the action step along.  See our replica of the Peace Clock.

Opposition to Subcrits slightly rebounding since 'Rebound' 

On June 10, 1997, Greenpeace and nearly 50 peace and environmental groups signed onto the following letter, calling on the President to cancel the subcritical tests.  The language of the letter was as follows:

"We strongly oppose the Department of Energy's plans to begin a series of subcritical, nuclear weapons-related experiments at the Nevada Test Site this June. We are not convinced that these controversial experiments are immediately needed to maintain the existing nuclear weapons in the U.S. stockpile. A number of eminent scientists, including the prestigious JASON group, share this view. Furthermore, we believe that these tests will be detrimental to U.S. efforts to stem the proliferation of nuclear weapons and to secure the international implementation of the Comprehensive Test Ban Treaty (CTBT).

 

The United States will set the pace for future progress on nuclear disarmament and non-proliferation. In our view conducting underground experiments involving chemical high explosives and nuclear weapons-grade plutonium at the nation's nuclear test site is a provocative step in the wrong direction. The tests send the message that the United States is more interested in advancing our nuclear weapons expertise than in advancing a non-proliferation and disarmament agenda.

 

Worse, the subcritical experiments set a dangerous precedent for other nations to conduct similar experiments and will make the challenging task of verifying the CTBT more difficult. For instance, Russia and China could feel free to conduct underground explosive experiments at their Novaya Zemlya and Lop Nor test sites. How can we be sure that such tests would not be used for new nuclear weapons development or would not violate the zero-yield CTBT?

 

The recently released JASON review of the first two subcritical experiments, commissioned by the Department of Energy, states that "there is no claim that the data from these experiments are needed immediately as part of the Science Based Stockpile Stewardship and Management Program in order to retain confidence in the reliability and performance of the U.S. stockpile..." (1). This review also makes a strong case that the plutonium data nuclear weapons scientists hope to obtain in these underground experiments can be obtained through the conduct of above ground experiments. The JASONs went on to recommend that "an independent review process should also address the scientific importance and cost-effectiveness of proposed subcritical experiments." We have yet to see such a review take place.

 

The best course builds on the success of the CTBT, now signed by over 140 countries including all five declared nuclear powers. President Clinton should cancel the subcritical experiments and establish a global standard against conducting nuclear weapons activities at nuclear test sites. Furthermore, the United States could demonstrate its commitment to upholding this emerging CTBT regime by seeking agreement with Russia and China to permanently close the world's remaining nuclear test sites - Nevada Test Site, Novaya Zemlya, and Lop Nor. France has closed its nuclear test sites in the South Pacific. The United Kingdom utilized the Nevada Test Site."

Congresspersons Cynthia McKinney and Ronald Dellums were joined by 42 other House Representatives in this letter sent to President Clinton on June 20, 1997:

Dear President Clinton:

We are extremely concerned that the Department of Energy (DOE) again plans to conduct underground subcritical nuclear weapons experiments at the Nevada Test Site. These experiments could severely damage global entry-into-force of the Comprehensive Test Ban Treaty (CTBT) which you worked so hard to achieve.

The DOE states that the proposed experiments are necessary to maintain a reliable nuclear stockpile. However, there is no evidence to date to suggest that potential problems such as plutonium aging have degraded the performance of the weapons designs in the active U.S. arsenal. Indeed, a 1997 JASON review states that "there is no claim that the data from these experiments are needed immediately as part of the Science Based Stockpile Stewardship and Management Program in order to retain confidence in the reliability and performance of the U.S. stockpile..."

The DOE has never conducted an independent technical review of the utility of the subcritical experiments, their timing or location, or their cost effectiveness; neither has it or other agencies conducted a formal evaluation of the nuclear arms control and non-proliferation impacts of conducting such activities. At a minimum, therefore, we believe that these experiments should not be conducted at this time.

The fact that these subcritical experiments would be conducted 900 feet underground — a depth sufficient to contain nuclear explosions with large yields — sets a precedent for conducting underground nuclear tests that a test ban treaty violator would find useful. Because the CTBT is not yet ratified, there are no existing verification standards nor methods by which to determine whether a nuclear weapons experiment violates the CTBT or not. The U.S. is unwisely creating a testing norm under which other nations could justify conducting similar underground nuclear weapons experiments at their test sites. An even more dangerous consequence is that countries with nuclear capability, but lacking the sophisticated testing technology of the declared nuclear weapons states, could be provoked to resume full-scale underground testing.

Mr. President, your admirable promotion of non-proliferation and your vision of a nuclear weapon-free 21st century is put at risk by a U.S. commitment to subcritical nuclear experiments.

We urge you to cancel these subcritical experiments. By establishing a prohibition on nuclear testing of any kind under the CTBT, the United States could set a global standard that would serve to promote treaty ratification, rather than undermine it, thereby building global security.

Sincerely,

Rep. Cynthia McKinney
Rep. Ronald Dellums

Opposition to subcriticals in the late 2000's has been sustained in particular by countries in East Asia.  

Nagasaki Mayor Itoh Iccho demanded the cancellation of the September 2006 subcritical nuclear test dubbed Unicorn, saying "It may give other countries a pretext for developing their nuclear weapons, amounting to an outrageous act that threatens the world peace and stability." [Political Affairs Magazine - 'Japan Peace Groups Say No to US Nuke Test'] 

After Unicorn was conducted on August 30, 2006, a South Korean group, the National Alliance for the Country's Reunification, stated (in early September 2006) that the United States' subcritical test was an "obvious criminal act of disturbing the global peace." About a month later, the North Korean government announced that it carried out its first nuclear test.  [The North Korean government's first public mention of a nuclear test came on Sept. 7, 2006, eight days after the United States' successfully carried out its 23rd subcritical nuclear experiment. In the Sept. 7th announcement, North Korea's Central News Agency repeated the above quote from the National Alliance for the Country's Reunification.]

Later, from early February through early May 2007, the U.S. government conducted 12 'Thermos experiments,' very small subcritical nuclear tests at the Nevada Test Site that were not announced beforehand.  

Peace organizations and other sovereign governments have repeatedly condemned subcritical tests since their inception. View (click on) our map below titled 'Map of the global conversation about the U.S.'s subcritical experiment program'

The Case of India 

There is reason to believe that India conducted its underground nuclear tests in 1998 to collect the necessary data in case it wanted to start a subcritical testing program.  This was likely in response to the first set of subcritical tests conducted by the U.S. in 1997.  

India was opposed to the U.S. subcritical testing program when the DOE announced its planned subcritical tests in 1996 but the South Asian country, that had gone nearly 25 years without testing a nuke, saw the 'writing on the wall' that the U.S. wasn't serious about disarmament. As the Peace Action newsletter states in their article 'Jesse Helms: Free the Test Ban!" in their Spring 1998 issue:

"The Indian government has been one of the most outspoken international critics of US Stockpile Stewardship - the Department of Energy's plan to expand its nuclear weapons research, development and experimental capabilities in absence of nuclear testing.  Indian officials point to the program, with its endless series of subcritical nuclear weapons experiments and resumed production of nuclear warheads, as evidence of US efforts to circumvent the core purpose of the test ban, "ending the development of advanced new types of nuclear weapons." Without a real commitment from the existing nuclear powers to pursue nuclear disarmament, they argue, India should not limit its own nuclear option.'¹

India decided it needed to advance its nuclear weapons, to improve its  'validation codes' (nuclear test knowledge), and in May 1998 conduct its first nuclear test since 1974.   Then quickly followed Pakistan's entrance into the nuclear club.  A nonprofit coalition sent a letter to President Clinton in July 1998 stating that:

'India has stated the need - to conduct nuclear tests - was in part based on the desire to advance their computer codes in order to benefit from a subcritical testing program of their own.'    [emphases ours]

(It's important to also mention that the U.S. gave technical support to India to improve its nuclear program: IBM sold them a supercomputer, LANL hosted 407 visiting Indian scientists from 1994 to 1997, and U.S. scientists taught India how to extract plutonium via reprocessing; also Canada supplied India with a nuclear reactor from which they extracted the plutonium for 'Smiling Buddha,' the 1974 N-test.)

Footnotes

¹ Peace Action Newsletter, Spring 1998

² p7.34; one facet of the SSP program, from the Green Book, would provide "a continuum of warhead design options" for the purpose of replacing Navy submarine warheads.  The 'Green Book' is really the October 1997 Department of Energy (DOE) Stockpile Stewardship and Management Plan: First Annual Update.

Side note:  Senator Harry Reid sent out a press release on October 6, 2009 stating that his amendment to a DOD appropriations bill had, in part, suggested that the Nevada Test Site 'play a key role in treaty verification and detection of nuclear weapons' and that the amendment would prepare us 'for stronger arms control agreements in the future.'  Subcritical tests go against the spirit of the most rigorous arms control agreement (CTBT; still not ratified by the Congress), are not being subjected to any international verification, and undermine and negate all nonproliferation efforts of the United States.   

In 1997, the U.S. let foreign journalists into the 'mines' of the Nevada Test Site to inspect a subcritical testing set-up, an one-time 'open house' that wasn't repeated for later subcritcal tests.  Ian Hoffman, a Albuquerque Journal journalist, noted in his 1997 article titled 'Activists: Experiments Subvert Treaty' that "Some arms-control advocates say DOE's reluctance to allow foreign observation of the experiments is a missed opportunity for the United States to be a role model for other nuclear nations."  

 Read about hydro-nuclear-tests at LANL

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Idealist's public document archives: 1. 2.

U.S. NUCLEAR tests: 128 A + 899 U in NV,
1 A in NM, 10 U (in NM, CO, AK, MS, central NV),
100+ A, U in Pacific, 3 A in S. Atlantic
(A=aboveground; U=Underground)

'The greatest irony of our atmospheric nuclear testing program is that 
the only victims of U.S. nuclear arms since World War II have been our own people.' 
- Forgotten Guinea Pigs Report, 1980

In 1986, the U.S. Dept. of Energy used the cover of the Chernobyl fallout cloud over the United States to release huge amounts of radiation into the air from a failed underground Nevada nuclear test. It was called Mighty Oak.

learn more on our global fallout page

 

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