|Fig. 1: Location (in orange, upper right) of the Semipalatinsk Nuclear Test Site. (Source: Wikimedia Commons)|
The Semipalatinsk Test Site (STS; unofficially "The Polygon") was the Soviet Union's first and largest major nuclear weapons testing complex. The site lies in eastern Kazakhstan, 160 km west of the city of Semipalatinsk (later renamed Semey). 
The location for STS was selected in late 1947 by Lavrenti Beria and Igor Kurchatov, the political and scientific heads of the Soviet nuclear weapons program, respectively. [1,2] A secret city (Semipalatinsk-21, now called Kurchatov City) to house the scientific, industrial, and military presence was soon founded, and development of the site proceeded rapidly thereafter. 
Russia's nuclear debut, a 22 kt surface blast codenamed "First Lightning" by the Soviets and "Joe-1" by the Americans, took place at STS on August 29, 1949. A total of 456 nuclear tests were eventually carried out at STS; 116 of these were atmospheric and 340 were underground. The last Soviet atmospheric test took place in December of 1962. The United States and the Soviet Union entered into the Limited Test Ban Treaty in 1963, drawing a close to the era of above-ground nuclear explosions. After almost three decades of continued underground testing, the last nuclear blast at STS took place on October 19, 1989. 
Lavrenti Beria described the Kazakh steppe surrounding the Semipalatinsk site as "uninhabited".  While the site itself was uninhabited, there are several small villages on the outskirts of the site, as a well as a major city (Semipalatinsk) within 160 km.  Apart from top Communist Party officials and villagers who lived close enough to witness the tests, the activities at Semipalatinsk were a closely guarded secret.  In modern interviews, "the villagers made it very clear that they had not been informed about the nature of the tests, or of the dangers linked to them". 
In the aftermath of nuclear testing at STS, the total number of people exposed to "substantial radiation doses" from 1949-1962 is estimated by Kazakhstan's Institute of Radiation Medicine and Ecology to have been between 500,000 and a million.  Most of this radiation exposure was due to short-lived airborne radionuclides released immediately after each test (up to 95% of the total dose within the first few weeks).  People in the villages nearest to STS were intially estimated to have received average doses around 2000 milli-Sieverts (mSv), with residents of the greater Semipalatinsk area receiving several hundred mSv.  (The generally accepted figure for normal human background radiation dosage is 3 mSv per year). However, follow-up studies have revealed that these estimates are too high by a factor of about 4. [6,7]
|Fig. 2: A crater at the former Semipalatinsk Nuclear Test Site. (Source: Wikimedia Commons)|
Surface contamination in areas surrounding STS has been found to be within the normal background of global fallout during the period of atmospheric nuclear testing. [8,9] However, the full effects of lingering environmental contamination are unclear due to a small geographic sample size. There are certainly still "hot spots" at the test sites themselves, though the cycling of residual radioactivity into the ecosystem and water sources is still poorly understood. [3,4,10]
It was not until 1956 that the Soviet Union began conducting clinical studies of the local residents, and only when residents of Ust-Kamengorsk (400 km from the explosion) were exposed to fallout so severe that 638 people were hospitalized due to acute radiation sickness. A permanent institution with the intentionally opaque title "Anti-Brucellosis Dispensary No. 4" was established to study health effects on the population surrounding STS. Upon the breakup of the USSR, this became the Institute of Radiation Medicine and Ecology (IRME), part of Kazakhstan's Ministry of Health. 
According to IRME, there was a noticeable rise in the number of congenital malformities (birth defects) in newborns, and a threefold increase in infant mortality by the year 1960. After 1960, infant mortality began to fall back towards historical levels, suggesting that atmospheric testing was in some way responsible.  A 1997 study of several villages in the immediate vicinity of STS shows that cancer mortality rates had almost quadrupled by 1975, mostly due to gastrointestinal cancers.  In the 1980s, a marked increase in respiratory and breast cancers was observed.  Zhumadilov et al. established a link between radionuclide exposure and thyroid cancer in villages close to the site. [12,13] A nearly two-fold risk of leukemia was found for local populations with the highest radiation exposure.  The rate of chromosomal abnormalities was studied in one village close to the test site; it was found that these rates were higher than those of the control group, but still within the normal range for elderly humans.  Although the human health consquences of nuclear testing at STS have been highly publicized (e.g., Zhumadilov et al., ), the scientific data remain incomplete. As most medical studies have been conducted in a geographically sparse manner close to the test site, it is generally agreed that ongoing research must be conducted to establish beyond a doubt the link between elevated rates of cancer and birth defects in the greater Semipalatinsk region and nuclear testing at STS. [3,10]
On February 26, 1989, the poet Olzhas Suleimenov interrupted a televised reading to address the issue of nuclear testing at Semipalatinsk. Two days later, a meeting of over 5,000 Kazakhs yielded a petition entitled "High Time," which called for the closure and cleanup of STS, civilian control over nuclear matters, and extensive research to solidify understanding of the geographical range of radiological contamination and its human consequences. The movement was known as the Nevada-Semipalatinsk Antinuclear Movement, a nod to the American test site. Nevada-Semipalatinsk rapidly gained momentum and international support; as a result, the Soviet Union cancelled 11 of the 18 nuclear tests scheduled in 1990.  After a majority vote by the Supreme Soviet, Kazakh president Nursultan Nazarbayev officially closed the site on August 29, 1991. 
In addition to the closure, Nazarbayev also ordered medical support and compensation for those affected by Soviet activities at Semipalatinsk. In 1992, Kazakhstan established a state support system for those affected by Soviet nuclear testing. 1.3 million people have since been recognized as such. Citizens designated as having "suffered" are entitled to the following (depending on their geographical location and degree of exposure): lump-sum compensation, salary and pension increases for state employees, paid holidays, extended maternity leave, and/or free medical treatment. Unfortunately, the dire economic situation in the 1990s partly prevented the Kazakh government from fulfilling its obligations. More recently, there has been "criticism regarding the size of compensation payments." 
The collapse of the Soviet Union left its former member states in terrible economic shape. Conditions in Kurchatov City itself were so bad that many residents were forced to scrap and sell parts of the remaining nuclear testing infrastructure. Even the Russian director of STS was fired in 1993 after he was caught selling equipment. Access to the Semipalatinsk site was entirely unrestricted for almost two decades, leaving a vacuum that would soon be filled by people excavating copper cable and steel rails left behind by the Soviets. Grazing of livestock on the site was also commonplace. This widespread poverty and desperation only exacerbated the existing public health problem by encouraging locals to try to scrape out a living on contaminated land. 
The consequences of the Soviet Union's collapse were not purely socioeconomic. The newly-independent Kazakhstan was suddenly left in possession of a major former nuclear weapons complex, with little hope of securing the site. Tens of thousands of Soviet troops abandoned their former posts, leaving a meager 500 Kazakh soldiers in control of the complex.  The 5,000 sq. km area containing virtually all of the STS nuclear tests was, for all practical purposes, unprotected. It would not be until 2009 that the Kazakh government created an "exclusion zone" around the most highly contaminated areas. 
|Fig. 3: Kurchatov City. (Source: Wikimedia Commons)|
The world was well aware of the proliferation danger posed by nuclear materials left behind in the ex-Soviet republics, and took steps to eliminate it. The early 1990s saw the removal of nuclear weapons from Ukraine, Belarus, and Kazakhstan. 1994's elaborate Operation Sapphire saw the United States airlift 600 kg of weapons-grade uranium from a Kazakh metallurgical plant. 
There was a less obvious, but no less important, proliferation danger present at Semipalatinsk. After atmospheric testing met with ever-increasing public opposition in the late 1950s, both superpowers commenced extensive underground nuclear testing. Degelen Mountain, a massif inside the Semipalatinsk site that contains a labyrinth of 181 tunnels and numerous boreholes, was host to the majority of the Soviet Union's underground tests. [1,18,19] After the Limited Test Ban Treaty went into effect, the Soviets detonated over 200 devices under Degelen Mountain. Each explosion consumed no more than 30 percent of the available fissile fuel, leaving the rest trapped underground.  In addition to full-scale nuclear explosions, subcritical experiments involving high explosives and fissile material were conducted to study the metallurgical properties of fissile materials under extreme conditions. While the United States always contained such tests in deep boreholes at Los Alamos, the Soviets sometimes conducted them on the surface, simply bulldozing the sites afterwards. Nobody bothered to consider the potential fate of plutonium residue left over from such experiments. 
The severity of the problem was not known to the Americans in 1995 when Los Alamos scientists were told by the Kazakhs that significant quantities of potentially recoverable weapons-grade material still laced the site. It was later estimated that "several hundred kilograms" of plutonium and uranium, enough for over a dozen bombs, was relatively accessible. By this time, herders and metal scavengers roamed STS trying to scrape a living out of the abandoned infrastructure. In 1998, Siegfried S. Hecker, a former Los Alamos director, personally visited STS and was appalled at what he saw: metal scavengers were using industrial machinery to unearth irradiated copper cables and to break into tunnels containing steel rails. Although the tunnels under Degelen Mountain were nominally "sealed," 110 of 181 of them had been breached by 2004.  Undocumented mining operations for gold, copper, aluminum, lead, coal, and beryllium were also underway. For most of the local Kazakhs, the plutonium and uranium lacing the site was simply an environmental and human health hazard. However, if a savvy terrorist knew what to look for, the recovery of enough fissile material for one or more nuclear bombs would have been a simple enough task. 
Hecker had developed personal connections with Russian scientists in the late 1980s during verification exercises for the mutual monitoring capabilities of the two superpowers under the Threshold Test Ban Treaty.  In the next few years, Hecker used these connections to initiate a secret project to secure the material at Semipalatinsk. In the end, the mutual trust of American, Soviet, and Kazakh scientists was critical to overcoming the diplomatic differences between governments in the aftermath of the Cold War. 
Eventually, the program moved forward. The three governments struck a clandestine deal in which the United States would pay for the cleanup, Russia would furnish critical information on the nature and location of relevant nuclear tests, and Kazakhstan would provide access to the site and to the necessary equipment. The entire operation was officially kept secret from the International Atomic Energy Agency (IAEA) due to fears that its involvement would complicate and jeopardize the success of the project. 
Work began in 2000. It was decided that the nuclear materials at STS would be sealed in-place by encasing test locations with iron-laced concrete, a mixture that would render chemical extraction of plutonium extremely difficult. Shallow surface experiments were paved over with 2 m thick slabs of steel-reinforced concrete.  An elaborate security system of remote sensors would be constructed as well. While this strategy did not completely rule out the possibility that a bomb's worth of plutonium could be extracted, it did ensure that such an effort would be conspicuous enough to be easily detected by the authorities. 
The project faced ongoing difficulties. Pressure to secure the nuclear materials at Semipalatinsk mounted in the aftermath of the 9/11 attacks, when documents uncovered in 2002 revealed Al Qaeda's nuclear ambitions. Although the Russians had entered into an agreement with Kazakhstan to provide information regarding Soviet-era nuclear activities, it was exceedingly reluctant to provide detailed information on the locations of tests and the nature of the materials in question. Russia also wanted nothing to do with the recovered "nuclear waste." In late 2005, Russia acknowledged the existence of several bomb components that, if found, could lead to the construction of a fairly sophisticated weapon. It was only after extended negotiations that Russia revealed their locations and agreed to take back two of them. 
In March 2012, Barack Obama, Dmitri Medvedev, and Nursultan Nazarbayev publicly announced the completion of the project. All told, the project had lasted 17 years and cost $150 million.  In October, a small monument was unveiled at the foot of Degelen Mountain with the inscription, "1996-2012. The world has become safer." 
This is by no means a definitive end to the danger at STS. Despite the safeguards and security measures at Degelen Mountain, legal mining operations within a few kilometers of the site could be used to disguise a covert operation to recover bomb materials, whose presence in the mountain is now publicly known. In addition, Plutonium-239's 25,000 year half-life far exceeds the hundred year timescale of most human activities, presenting a long-term risk. 
© Devon Powell. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
 R.S. Norris and T.B. Cochran, "Nuclear Weapons Tests and Peaceful Nuclear Explosions by the Soviet Union: August 29, 1949 to October 24, 1990," Natural Resource Defense Council, October 1996.
 J. Taylor, "The World's Worst Radiation Hotspot," The Independent, 10 Sep 09.
 R. Vakulchuk et al., "Semipalatinsk Nuclear Testing: The Humanitarian Consequences," Norwegian Institute of International Affairs, Report No. 1, February 2014.
 R. Stone, "Plutonium Fields Forever," Science 300, 1220 (2003).
 B. I. Gusev, Z. N. Abylkassimova, and K. N. Apsalikov, "The Semipalatinsk Nuclear Test Site: a First Assessment of the Radiological Situation and the Test-Related Radiation Doses in the Surrounding Territories," Radiat. Environ. Biophys. 36(3), 201 (1997).
 S.L. Simon, "Evaluation of Possible Radiation Exposures Near the Semipalatinsk Nuclear Test Site," in Nuclear Physical Methods in Radioecological Investigations of Nuclear Test Sites, ed. by S. S. Hecker et al., NATO Science Series 31 (springer, 2000), p. 153.
 S. L. Simon, K. F. Baverstock, and C. Lindholm C, "A Summary of Evidence on Radiation Exposures Received Near to the Semipalatinsk Nuclear Weapons Test Site in Kazakhstan," Health Phys. 84(6), 718 (2003).
 R. Hille et al., "Population Dose Near the Semipalatinsk Test Site," Radiat. Environ. Biophys. 37, 143 (1998).
 P. Stegnar and T. Wrixon, "Semipalatinsk Revisited: Radiological Evaluation of a Former Nuclear Test Site," IAEA Bull. 40, No. 4, 12 (1998).
 T.M. Carlsen et al., "Radionuclide Contamination at Kazakhstan's Semipalatinsk Test Site: Implications on Human and Ecological Health," Lawrence Livermore National Laboratory, UCRL-JC-143920, June 2001.
 B. I. Gusev, R. I. Rosenson, and Z. N. Abylkassimova, "The Semipalatinsk Nuclear Test Site: A First Analysis of Solid Cancer Incidence (Selected Sites) Due to Test-Related Radiation," Radiat. Environ. Biophys. 37 209, (1998).
 Z. Zhumadilov et al., "Fallout Exposure in the Semipalatinsk Nuclear Test Site Area and the Induction of Thyroid Nodules Diseases," Int. Cong. Ser. 1236, 47 (2002).
 Z. Zhumadilov et al., "Thyroid Abnormality Trend Over Time in Northeastern Regions of Kazakstan, Adjacent to the Semipalatinsk Nuclear Test Site: a Case Review of Pathological Findings for 7271 Patients," J. Radiat Res. 41, 35 (2000).
 Z. Abylkassimova et al., "Nested Case-Control Study of Leukemia Among a Cohort of Persons Exposed to Ionizing Radiation From Nuclear Weapon Tests in Kazakhstan (1949-1963)," Ann Epidemiol. 10, 479 (2000).
 A. Testa et al., "Cytogenetic Biomonitoring Carried Out in a Village (Dolon) Adjacent to the Semipalatinsk Nuclear Weapon Test Site," Radiat. Environ. Biophys. 40, 125 (2001).
 P. Zheutlin, "Nevada, U.S.S.R.," Bull. Atomic Scientists 46, No. 2, 10 (March 1990).
 V. Kianitsa, "Test Anxiety," Bull. Atomic Scientists 49, No. 8, 37 (October 1993).
 E. Harrell and D.E. Hoffman, "Plutonium Mountain: Inside the 17-Year Mission to Secure a Dangerous Legacy of Soviet Nuclear Testing," Harvard Kennedy School Belfer Center, August 2013.
 E. Barry, "Old Soviet Nuclear Site in Asia Has Unlikely Sentinel: The U.S.," New York Times, 21 May 11.
 S. S. Hecker, "The Story of Plutonium Mountain," Bull. Atomic Scientists 69, No. 5, 1 (2013).