Science and Global Security

An evaluation is made of requirements for, and advantages in, the creation of a manned lunar base whose functions emphasize astronomical investigations. These astronomical studies would be able to capitalize on the lunar environment's ultrahigh vacuum, highly stable surface, dark and cold sky, low-G, absence of wind, isolation from terrestrial 'noise', locally usable ceramic raw materials, and large radiotelescope dish-supporting hemispherical craters. Large telescope structures would be nearly free of the gravity and wind loads that complicate their design on earth.

Antineutrinos are electrically neutral, nearly massless fundamental particles produced in large numbers in the cores of nuclear reactors and in nuclear explosions. In the half century since their discovery, major advances in the understanding of their properties, and in detector technology, have opened the door to a new discipline: Applied Antineutrino Physics. Because antineutrinos are inextricably linked to the process of nuclear fission, many applications of interest are in nuclear nonproliferation. This white paper presents a comprehensive survey of applied antineutrino physics relevant for nonproliferation, summarizes recent advances in the field, describes the overlap of this nascent discipline with other ongoing fundamental and applied antineutrino research, and charts a course for research and development for future applications. It is intended as a resource for policymakers, researchers, and the wider nuclear nonproliferation community.

We investigate the problem of detecting the presence of clandestine neutron sources, such as would be produced by nuclear weapons containing plutonium, within cargo containers. Small, simple and economical semiconductor photodiode detectors affixed to the outsides of containers are capable of producing statistically robust detections of unshielded sources when their output is integrated over the durations of ocean voyages. It is possible to shield such sources with thick layers of neutron-absorbing material, and to minimize the effects of such absorbers on ambient or artificial external neutron fluxes by surrounding them with neutron-reflective material.

The problem of detecting a nuclear weapon smuggled in an ocean-going cargo container has not been solved, and the detonation of such a device in a large city could produce casualties and property damage exceeding those of September 11, 2001 by orders of magnitude. Any means of detecting such threats must be fast and cheap enough to screen the millions of containers shipped each year, and must be capable of distinguishing a threatening quantity of fissionable material from the complex loading of masses of innocent material found in many containers. Here we show that radiography with energetic X-rays produced by a 10 MeV electron accelerator, taking advantage of the high density and specific atomic properties of fissionable material, may be a practical solution.

The conflict in Yugoslavia has been a source of great concern due to the radiological and toxic hazard posed by the alleged presence of depleted uranium in NATO weapons. In the present study some worst-case scenaria are assumed in order to assess the risk for Yugoslavia and its neighboring countries . The risk is proved to be negligible for the neighboring countries while for Yugoslavia itself evidence is given that any increase in total long-term cancer mortality will be so low that it will remain undetected. Local radioactive hotspots such as DU weapons fragments and abandoned battle tanks, fortified or contaminated with DU, constitute a post-war hazard which is not studied in this article.

This paper assesses the radiological and chemical hazards resulting from the use of depleted uranium (DU) munitions. Due to the low radioactivity of DU, radiological hazards to individuals would become significant in comparison to natural background radiation doses only in cases of prolonged contact---for example, when shards of a DU penetrator remain embedded in a soldier's body. Although the radiation doses to virtually all civilians would be very low, the cumulative "population dose" resulting from the dispersal of hundreds of tons of DU, as occurred during the Gulf War, could result in up to ten cancer deaths. It is highly unlikely that exposures of persons downwind from the use of DU munitions or consuming food or water contaminated by DU dust would reach the estimated threshold for chemical heavy-metal effects. The exposures of soldiers in vehicles struck by DU munitions could be much higher, however, and persons who subsequently enter such vehicles without adequate respiratory protection could potentially be at risk. Soldiers should be trained to avoid unnecessary exposure to DU, and vehicles struck by DU munitions should be made inaccessible to curious civilians. INTRODUCTION

A survey of different measurement techniques applicable in the context of the attribute approach for warhead authentication is presented to demonstrate current capabilities and gaps. Therefore, their technical advantages and limitations will be assessed, in particular in terms of correctly characterizing an item whose configuration is not entirely known to an inspecting party. Passive and active neutron and gamma measurements assessing the presence of fissile material, isotopic composition and fissile mass of plutonium and uranium are considered.

Most asteroid and comet impacts cause localized destruction, not global-scale extinctions. The way in which the international community would respond to such events has not been defined. During the 10th European Science Foundation IMPACT workshop in 2003 a method of scientific response to an impact event was proposed. A Scientific Impact Response Team (SIRT) would achieve the rapid assembly of a scientific and logistics team to access and study a newly formed impact crater (or blast zone under an airburst). Its purpose would be to (1) provide scientific advice and information for disaster and emergency services if such an event occurs near to a populated area, (2) provide scientific advice to media and public information channels, (3) investigate immediate postimpact geological and biological effects in and around the crater, and (4) document geological and biological changes at the site of impact over time and the rate of recovery. The team would exist in a latent state. In order to ensure a coherent response to such an event, the team could be activated by international bodies such as the UN and would maintain links with other emergency response organizations.

Verification technologies based upon electromagnetics and acoustics could potentially play an important role in fulfilling the challenging requirements of future verification regimes. For example, researchers at the Pacific Northwest National Laboratory (PNNL) have demonstrated that low frequency EM signatures of sealed metallic containers can be used to rapidly confirm the presence of specific components on a “yes/no” basis without revealing classified information. PNNL researchers have also used ultrasonic measurements to obtain images of material microstructures which may be used as templates or unique identifiers of treaty accountable items (TAIs). Such alternative technologies are suitable for application in various stages of weapons dismantlement and often reduce or eliminate classified data collection because of the physical limitations of the method. In such cases the need for an information barrier to prevent access to classified data is potentially eliminated, thus simplifying verification scenarios. As a result, these types of technologies may complement traditional radiation-based verification methods for arms control.This article presents an overview of several alternative verification technologies that are suitable for supporting a future, broader and more intrusive arms control regime that spans the nuclear weapons dismantlement lifecycle. The general capabilities and limitations of each verification modality are discussed and example technologies are presented. These technologies are relevant throughout a potential warhead monitoring regime, from entry into chain of custody (i.e., establishing confidence in the authenticity and integrity of the warhead) to dismantlement and final material disposition (i.e., maintaining confidence that chain of custody has not been broken).

The technical verification of a possible future nuclear arms control agreement is a complex challenge for technology developers. The focus of this article is on the use of modal testing techniques as a method for maintaining a chain of custody over containerized treaty accountable items (TAI) and monitoring equipment. Modal testing is a specialized form of resonant vibration analysis often used for the purpose of structural identification, condition monitoring, and damage detection. From a chain of custody perspective, it was postulated that a modal vibration signature might be used to identify a particular treaty accountable container or container/object system, or provide evidence of tampering. This article considers the advantages and disadvantages of modal testing as a potential chain of custody tool. Experimental results are discussed relating to deployment, tamper indication, unique identification and data analysis methodology.

Senate Hearings on the GAO report on the nuclear triad and on the START treaty showed that vulnerabilities of the U.S. triad were vastly over‐stated, that the performance of new projected strategic systems was over‐estimated, and that the performance of existing U.S. strategic systems was under‐estimated. These exaggerations enhanced the psychological (Freud) aspects of the Cold War and compromised logic (Newton). With the end of the Cold War it is imperative that we re‐examine the basic premises that guided the choices of the strategic nuclear systems. The initial bottom line is that these systems were successful in that they did deter nuclear war without destroying either or both superpowers. However, now that the emotion of the conflict has passed, the effectiveness of the nuclear triad should be examined to determine how much was enough and which technical conventional wisdoms were incorrect. As this paper documents, incorrect technical estimates took place. These errors (and/or exaggerations) caused the U.S. to greatly increase the capabilities of its nuclear triad. At a minimum, these errors were fiscally wasteful, and at a maximum they could have endangered the stability between the countries. This paper examines technical aspects of the robustness of the triad, rather than the psychological causes and consequences of worst‐case analysis. When more historical data becomes available, other authors should examine the effects of the U.S. nuclear build up on Soviet behavior (e.g., why Gorbachev was willing to let the Berlin wall fall and reduce the Warsaw Pact forces by 60% without requiring NATO reductions). The technical conclusions of this paper are based on the author's staffing 20 hearings [1] on the START treaty before the Senate Foreign Relations Committee, and the Senate Governmental Affairs Committee hearing [2] on the General Accounting Office report, The U.S. Nuclear Triad: GAO's Evaluation of the Strategic Modernization Program. The GAO study produced a massive eight volume classified report which, according to the GAO, was the most complete examination of strategic nuclear forces in the past three decades.

We have attempted to detect seismic signals from small explosions in North Korea on five specific days in 2010 that feature in scenarios proposed by De Geer. We searched the seismic data recorded by station MDJ in northeastern China, applying three-component cross-correlation methods using signals from known explosions as templates. We assess the capability of this method of detection, and of simpler methods, all of which failed to find seismic signals that would be expected if De Geer's scenarios were valid. We conclude that no well-coupled underground explosion above about a ton occurred near the North Korea test site on these five days and that any explosion would have to be very small (local magnitude less than about 2) to escape detection.

This article investigates the possibility presented by De Geer (2012) that radionuclides detected at stations in South Korea, Japan, and Russia in May 2010 were evidence that North Korea conducted at least one unannounced low yield nuclear test on 11 May. It provides HYSPLIT (Hybrid Single Particle Lagrangian Integrated Trajectory Model) atmospheric transport modeling of the observed radionuclides assuming candidate origins in North Korea, ROK, Japan, Russia, mainland China, and Taiwan. Xenon activity calculations for reactor- and explosion-produced isotopes are used to ascertain possible release ratios and source terms. The HYSPLIT modeling finds that the most likely origin of the radionuclides is close to the site of North Korea's declared nuclear tests in 2006 and 2009. The activity calculations show that the source term is consistent with a nuclear test up to a few hundred tons yield. These results are discussed in the context of a decoupled but uncontained nuclear test by North Korea on 11 May 2010. If the scenario suggested by De Geer and supported here is correct, it seems that there is a significant possibility of detecting even a small, decoupled nuclear test in North East Asia using components of the International Monitoring System of the Comprehensive Test Ban Treaty.

The United States produced about 2 tons of uranium-233, a weapons-useable fissile material, as part of its military and civilian nuclear program. Of that, 1.55 tons was separated at costs estimated to be between $5.5 and $11 billion. Of the 1.55 tons, approximately 96 kg of uranium-233 may be unaccounted for. There are also varying site-specific estimates suggesting that material control and accountability of the U.S. uranium-233 inventory needs to be more stringent. About 428 kg of uranium-233 is stored at the Oak Ridge National Laboratory (ORNL), in Tennessee at Building 3019, a 69-year-old structure which DOE describes as the “oldest operating nuclear facility in the World” and one that does not meet current safeguards and security requirements.Currently, the U.S. Department of Energy's (DOE) goal for disposition of the 428 kg is 2018, more than 20 years after significant environmental, safety, and security vulnerabilities were first officially acknowledged. To meet this goal, DOE plans to waive its own waste acceptance criteria to allow direct shallow land disposal of a large portion of the uranium-233 by August 2014. Granting a disposal waiver sets a bad precedent for international safeguards and standards for the disposal of reprocessed wastes containing high concentrations of fissile materials.

This article provides an independent cost estimate for uranium production from seawater through the braid-type adsorbent recovery system proposed by the Japan Atomic Energy Agency (JAEA). Production costs were developed with standard engineering cost estimation techniques using vendor data and plant design and operational data. The analysis includes life cycle discounted cash flows, economies of scale, and propagation of uncertainties. A reference case based on the Japan Atomic Energy Agency assessment, with a fresh adsorbent capacity of 2 kgU/t ads and 6 recycles, yielded a production cost of $1230/kg uranium with a 95 percent confidence interval of [$1030/kg U, $1430/kg U] when component cost uncertainties alone were considered. Sensitivity studies confirmed that adsorbent capacity, number of recycles, and capacity degradation are major cost drivers. If capacity and number of recycles increases to 6 kg U/t ads and 20, respectively, with no degradation and unchanged adsorbent production costs, the uranium production cost drops to $299/kg U.Supplemental materials are available for this article. Go to the publisher's online edition of Science & Global Security to view the free online appendix with additional tables and figures.

This article presents a method developed to assess laser Directed Energy Weapon engagements. This method applies physics-based models, which have been validated by experiments. It is used to assess the capabilities of the Airborne Laser (ABL), a system for boost phase missile defense purposes, which is in development under supervision of the U.S. missile defense agency. Implications for international security are presented. The article begins with a general introduction to laser Directed Energy Weapons (DEW). It is notable that several laser directed energy weapon prototypes have recently become operational for testing. One of them is the ABL, a megawatt-class laser installed into a cargo aircraft. It is concluded that only the ABL could have significant political impact on an international scale at the moment. Hence, the remainder of the article focuses on the assessment of that system. The laser intensity, the induced temperature increase of a target and the impact of this temperature increase on the mechanical properties of the target are calculated for different scenarios. It is shown that the defensive capability of the ABL against ballistic missiles is limited. Even a successful laser engagement that deflects a missile trajectory from its intended target can have negative impact for third parties, as missile warheads will most likely not be destroyed.

This article develops a mathematical modeling framework using fault trees and Poisson processes for analyzing the risks of inadvertent nuclear war from U.S. or Russian misinterpretation of false alarms in early warning systems, and for assessing the potential value of options to reduce the risks of inadvertent nuclear war. The model also uses publicly available information on early warning systems, near-miss incidents, and other factors to estimate probabilities of a U.S.–Russia crisis, the rates of false alarms, and the probabilities that leaders will launch missiles in response to a false alarm. The article discusses results, uncertainties, limitations, and policy implications.Supplemental materials are available for this article. Go to the publisher's online edition of Science & Global Security to view the free online appendix with additional tables and figures.

Gaseous diffusion was historically the most widely used technology for military production of highly enriched uranium. Since June 2013, all gaseous diffusion enrichment plants worldwide are permanently shut down. The experience with decommissioning some of these plants has shown that they contain large amounts of uranium particles deposited in the cascade equipment. This article evaluates the potential of using uranium particle deposition to understand and reconstruct the operating histories of gaseous diffusion enrichment plants. First, a squared-off cascade enrichment model is derived to estimate the enrichment capacity of a reference plant. Then, using a cross-flow filtration model, the mass of solid uranium particles deposited over time in the tubular separation membranes of the stage diffusers is calculated. Finally, potential techniques to characterize these uranium deposits and help reconstruct the operating history of the plant are assessed.

The uranium-235 content of a uranium enrichment plant’s product is related to the uranium-234 content of its waste, allowing one to check with tails measurements consistency with a plant’s declared past production. Verification works best with known feed material, but with unknown feed isotopics the production of low and high enriched uranium may still be distinguished based on tails measurements. Estimating product masses is harder, and concealment scenarios are discussed. With traditional nuclear accounting, relationships between product and waste isotopics, or “nuclear archaeology,” can increase confidence in the accuracy of declarations of past fissile material production.

This report describes the value proposition for a “nuclear archaeological” technical capability and applications program, targeted at resolving uncertainties regarding weapons fissile materials production and use. Central to this proposition is the notion that one can never be sure that all fissile material is adequately secure without a clear idea of what “all” means, and that uncertainty in this matter carries risk. We argue that this proposition is as valid today, under emerging state and possible non-state nuclear threats, as it was in an immediate post-Cold-War context, and describe how nuclear archaeological methods can be used to verify fissile materials declarations, or estimate and characterize historical fissile materials production independent of declarations. Methods for accurately estimating plutonium production from graphite reactors have been demonstrated and could be extended to other reactor types. Proposed techniques for estimating HEU production have shown promise and are under development.

This article describes the status of China's military and civilian nuclear programs, fissile material production and associated nuclear facilities, and the Chinese nuclear experts and officials’ perspectives on the nuclear terrorism threat. It gives details of China's nuclear security practices, attitudes, and regulations, as well as identifying areas of concern. The article recommends ways to strengthen China's nuclear material protection, control, and accounting systems and suggests opportunities for increased international cooperation.

Converting research reactors from highly enriched uranium (HEU) fuel to more proliferation-resistant low-enriched fuel is critical for achieving the objective of ending the use of directly weapon-usable materials in the civilian nuclear fuel cycle. The most challenging type of reactors to convert are high-flux research reactors, which, along with upcoming strong spallation sources, are the most important neutron sources for sophisticated neutron scattering experiments. Advanced Monte-Carlo computer codes are now available that make it possible to track neutrons from the neutron source, through neutron guides, to the detector of a neutronic experimental setup, including realistic samples. These “virtual experiments” allow optimizing the performance of complete beamlines, where in many cases a large unused potential exists for increasing the neutron flux at the sample or detector position. The Monte-Carlo codes VITESS and McStas are used to compare results for typical neutron scattering setups using typical versus state-of-the-art technologies. The analysis shows that performance gains due to instrument upgrades or neutron guide renewals can dwarf potential neutron flux losses due to conversion to low-enriched fuel. Combined convert-and-upgrade strategies therefore offer unique opportunities for reactor operators and neutron scientists to significantly improve the overall performance of research facilities, and turn them into centers of excellence, while supporting the objective of phasing out the use of highly enriched uranium in the civilian nuclear fuel cycle as soon as possible.

Scientists have, within the frame of the Conference on Disarmament, been successfully engaged in support of the Comprehensive Nuclear Test Ban Treaty (CTBT) for many decades, starting long before negotiations began. This article proposes an International Scientific Network (ISN) to engage the global scientific community to explore how scientific and technological developments can support nuclear disarmament and non-proliferation. It reviews the experience gained from scientific work on the CTBT and identifies a broad range of science and technologies that might be the focus of an ISN. A key question is how such an international scientific cooperation can be created in the absence of an existing established political or managerial framework.

The mobile ICBM displayed in Pyongyang last April is analyzed in light of North Korea's known and reasonably suspected capabilities in the field, particularly those demonstrated in the recent and successful Unha-3 launch. Several possible configurations for the “KN-08” missile are given, and performance estimates are presented. While the displayed missiles are clearly mock-ups, they are consistent with an ongoing development program for a missile with limited intercontinental capability using only existing North Korean technology. The lack of flight testing strongly suggests that operational deployment is still months or years in the future, though an initial test could come at any time. Even with a successful test program, any such North Korean ICBM would likely be unreliable, limited in mobility and performance, and available only in small numbers.

Radioxenon is an important atmospheric tracer to detect underground nuclear explosions. The International Monitoring System is designed to provide worldwide continuous physical monitoring and detection of nuclear explosions and incorporates 40 noble gas monitoring stations. They are constantly sampling the atmosphere for concentrations of radioxenon. This work analyses how effectively the network of stations is able to detect unusual xenon-133 concentrations in the atmosphere. A large multitude of nuclear explosions, evenly distributed in space and time, is simulated and the detection rate is calculated. Atmospheric transport modelling is applied to calculate the source-receptor-sensitivities for each monitoring station. The approach includes the anthropogenic radioxenon background, station-specific detection criteria, different scenarios for surface and subsurface nuclear explosions, and a spatial as well as a time dependent analysis. Recommendations are drawn for the improvement of the detection capability.

In 1958, the Soviet physicist Andrei Sakharov published an estimate of the long-term health impacts from carbon-14 produced by nuclear test explosions in the atmosphere. At the time, Sakharov was an important contributor to the Soviet Union's development of multi-megaton thermonuclear weapons. This was Sakharov's first public expression of concern about the weapons work in which he was involved. Subsequently, he became a campaigner for human rights in the Soviet Union and for international cooperation and received the 1975 Nobel Peace Prize in recognition of the importance of his efforts. This article provides some context for his estimate and compares it with estimates based on dose estimates by the UN Scientific Committee on Effects of Atomic Radiation and dose-effect estimates by the US National Academies.

Since the early 1960s, Israel has used the Dimona reactor in the Negev Desert for unsafeguarded plutonium production. Estimates of cumulative plutonium production have been very uncertain, however, because the power level of the reactor is unknown, and there is a lack of detail about the reactor design. This analysis presents new estimates of historic plutonium production in Israel based on neutronics calculations for the Dimona reactor. As of December 2020, we estimate that the cumulative production of plutonium is 830 ± 100 kg. Israel continues to operate the Dimona reactor today, possibly to offset the decay of its stock of tritium. For these reasons, the production of tritium and the possible production of enriched uranium are also briefly discussed. Calculations suggest that the reactor could make on the order of 50–60 grams of tritium and support an arsenal of about one hundred advanced nuclear weapons. The paper also includes a critical review of the 1986 testimony by the Dimona technician and whistleblower Mordechai Vanunu, which provided much of the basis for public discussion of the reactor’s power and operation.

This article offers a new analysis of radionuclide and hydroacoustic data to support a low-yield nuclear weapon test as a plausible explanation for the still contentious 22 September 1979 Vela Incident, in which U.S. satellite Vela 6911 detected an optical signal characteristic of an atmospheric nuclear explosion over the Southern Indian or Atlantic Ocean. Based on documents not previously widely available, as well as recently declassified papers and letters, this article concludes that iodine-131 found in the thyroids of some Australian sheep would be consistent with them having grazed in the path of a potential radioactive fallout plume from a 22 September low-yield nuclear test in the Southern Indian Ocean. Further, several declassified letters and reports which describe aspects of still classified hydroacoustic reports and data favor the test scenario. The radionuclide and hydroacoustic data taken together with the analysis of the double-flash optical signal picked up by Vela 6911 that was described in a companion 2017 article (“The 22 September 1979 Vela Incident: The Detected Double-Flash”) can be traced back to sources with similar spatial and temporal origins and serve as a strong indicator for a nuclear explosion being responsible for the 22 September 1979 Vela Incident.

On 22 September 1979 two optical sensors on U.S. satellite Vela 6911 detected a double-flash of light that appeared characteristic of an atmospheric nuclear explosion conducted over the southern Atlantic or Indian Ocean. It became known as the Vela Incident, Event 747, or Alert 747. An anomaly between the amplitude of the two signals during the second pulse led a U.S. government expert panel established to assess the event to conclude in mid-1980 that a more likely explanation was the impact of a small meteoroid on the satellite, the debris from which reflected sunlight into the sensors' field of view. No model was presented to support the contention, and a similar anomaly—known as background modulation—was a given for the second pulse of all confirmed explosions detected by Vela, though beginning later. Nonetheless, this event has remained the subject of intense debate. This article reviews the evidence and presents an updated analysis of the original Vela signal based on recently declassified literature and on modern knowledge of interplanetary dust and hyper velocity impact. Given the geometry of the satellite, and that the bulk of the surface comprised solar panels, much of the debris from any collision would be carried away from the sensors' field of view. Thus, a meteoroid collision appears much less likely than previously assumed. The double flash is instead consistent with a nuclear explosion, albeit detected by an aged satellite for which background modulation was abnormal and/or commenced earlier, also seen in post-event SYSTEM tests. A companion paper to be published in 2018 presents radionuclide and hydroacoustic evidence supporting the conclusion that the Vela Incident was a nuclear weapon test explosion.

In this article a case study of the application of antineutrino safeguards to a real-world scenario, the North Korean nuclear crisis in 1994, is presented. Detection limits to a partial or full core discharge in 1989 based on actual IAEA safeguards access are derived and it is found that two independent methods would have yielded positive evidence for a second core with very high confidence. To generalize these results, detailed estimates for the sensitivity to the plutonium content of various types of reactors, including most types of plutonium production reactors, are presented, based on detailed reactor simulations. A key finding of this study is that a wide class of reactors with a thermal power of 0.1–1 gigawatt can be safeguarded achieving IAEA goals for quantitative sensitivity and timeliness with antineutrino detectors adjacent to the reactor building. Antineutrino reactor monitoring does not rely on the continuity of knowledge and provides information about core inventory and power status in a timely fashion. The necessary detection systems do not exist yet but are expected to become available within two to five years.

Here I review Daniel Deudney's interesting and important book: Dark Skies: Space Expansionism, Planetary Geopolitics, and the Ends of Humanity (published by Oxford University Press, 2020).

The ability to extract three-dimensional (3D) data from two-dimensional satellite images provides opportunities to apply novel geospatial techniques to problems relating to nuclear arms control, nonproliferation, and disarmament. This study demonstrates some of these techniques by estimating the plutonium production capacity of the heavy water nuclear reactors at the Khushab complex in Pakistan, where since 1998 Pakistan has produced plutonium for its nuclear arsenal. Three-dimensional analysis is used to assess the viability of using the horizontal cross-sectional area of the Khushab reactors’ mechanical draft cooling towers to estimate the thermal capacity of each reactor and set an upper bound for the reactors' abilities to produce plutonium. The horizontal area approach suggests the three completed Khushab reactors have a thermal power of 40–90 MWt each. The results suggest that a horizontal area approach can be used successfully with the Khushab reactors, as well as other low power, research-type reactors employing mechanical draft cooling towers.

In 2000, Russia and the United States signed the Plutonium Management and Disposition Agreement to dispose of 34 tons of declared excess weapon plutonium each. A 2010 amendment allows Russia to dispose of its weapon-grade plutonium as MOX fuel in its BN-600 and BN-800 fast reactors with the condition that 30 years after irradiation the spent fuel must still emit at least one sievert per hour. Using depletion simulations for the BN-800 reactor, this note presents dose rates for fuel and blanket materials after different irradiation and cooling times. After the full irradiation time of 420 days, the fuel fulfills the disposition criteria. This is not true for shorter irradiation times, however. Furthermore, the dose rate from blanket elements, which breed weapon grade plutonium, declines even more quickly after irradiation. For some blanket element positions, the spent fuel standard is not fulfilled after 960 days of irradiation. To provide confidence in the agreement, Russia, the United States and the International Atomic Energy Agency should agree on monitoring of reactor power and irradiation times for plutonium disposition in such fast reactors.

According to the Plutonium Management and Disposition Agreement, which was signed in 2000 and amended in 2010, Russia and the United States agree to dispose of 34 tons of excess weapon plutonium each. Russia plans to use the plutonium as fuel in its sodium-cooled fast reactors BN-600 and BN-800. This article analyzes BN-800 core models with and without breeding blankets for the plutonium isotopic vector in spent fuel, plutonium production in breeding blankets, breeding ratios for different plutonium concentrations in fuel, and possible annual material throughput. It finds that any spent fuel in the core contains less than 90 wt% plutonium-239, but using breeding blankets the reactor can be configured to be a net producer of plutonium, even with a breeding ratio below one, and that plutonium produced in blankets will be weapon-grade.

Tanks holding liquid high level waste from reprocessing spent fuel have large inventories of highly radioactive materials. These tanks could potentially be damaged by a variety of chemical explosions, leading to the dispersion of a significant fraction of their radioactive contents. This article describes some of the different chemical explosions that could occur and examines how such explosions could occur at the Kalpakkam Reprocessing Plant in India, which likely stores a large volume of high level liquid waste because vitrification of that waste did not begin until more than 15 years after the plant began operating in 1998. The atmospheric dispersion of the hypothetical radioactive release is modeled using the Hybrid Single-Particle Lagrangian Integrated Trajectory Model developed by the Air Research Laboratory of the U.S. National Oceanic and Atmospheric Administration. The results suggest that the modeled accident scenario would lead to nearly 97,000 cancers, with roughly 47,000 of these being fatal. Larger radioactive releases are possible and would lead to proportionately higher incidence of cancer and cancer-caused mortality.

Proponents of high temperature gas cooled reactors argue that the reactor type is inherently safe and that severe accidents with core damage and radioactive releases cannot occur. The argument is primarily based on the safety features of the special form of the fuel. This paper examines some of the assumptions underlying the safety case for high temperature gas cooled reactors and highlights ways in which there could be fuel failure even during normal operations of the reactor; these failures serve to create a radioactive inventory that could be released under accident conditions. It then describes the severe accident scenarios that are the greatest challenge to high temperature gas cooled reactor safety: ingress of air or water into the core. Then, the paper offers an overview of what could be learned from the experiences with high temperature gas cooled reactors that have been built; their operating history indicates differences between actual operations and theoretical behavior. Finally, the paper describes some of the multiple priorities that often drive reactor design, and how safety is compromised in the process of optimizing other priorities.

Bayesian methods are used to compare the predictions of probabilistic risk assessment—the theoretical tool used by the nuclear industry to predict the frequency of nuclear accidents—with empirical data. The existing record of accidents with some simplifying assumptions regarding their probability distribution is sufficient to rule out the validity of the industry’s analyses at a very high confidence level. This conclusion is shown to be robust against any reasonable assumed variation of safety standards over time, and across regions. The debate on nuclear liability indicates that the industry has independently arrived at this conclusion. Paying special attention to the case of India, the article shows that the existing operating experience provides insufficient data to make any reliable claims about the safety of future reactors. Finally, policy implications of the article findings are briefly discussed.

This paper is an assessment of cybersecurity principles within the nuclear arsenal of the United States, specifically the nuclear-armed intercontinental ballistic missile forces. Ongoing modernizations will introduce new components, and potentially new vulnerabilities, into U.S. nuclear forces. The principles for achieving secure operations from the fields of computer security, dependable computing, and systems analysis, and the extent to which they are addressed within the management of U.S. nuclear intercontinental ballistic missiles is discussed. This paper then considers the types of vulnerabilities that may be overlooked during modernizations, followed by a critique of U.S. nuclear command and control policy choices that could make the consequences of these vulnerabilities more catastrophic.

The Democratic People’s Republic of Korea (DPRK)’s only confirmed uranium mill is within the Pyongsan uranium mining complex. The ore processing pathway and the production capacity for uranium concentrate is analyzed, based on comprehensive satellite imagery analysis of this facility. This assessment of the Pyongsan facility indicates an ore processing capacity of ∼750–1,200 tonnes per day. One year of maximum production at Pyongsan would yield enough processed ore to fuel one load of the 5 MWe reactor in Yongbyon as well as ∼3,000 kg of LEU or ∼100 kg of HEU. The analysis suggests that the ore processing capacity at Pyongsan is not a constraint on the DPRK’s nuclear material production and that the available capacity at the Pyongsan milling facility strongly suggests that the DPRK has no need in another uranium milling facility of a comparable size. This report provides an improved understanding of the ore processing steps and production rates of the only confirmed uranium mill in the DPRK, enabling a more quantitative assessment of its nuclear materials production and inventories.

Remote monitoring of krypton-85 from undeclared reprocessing of spent nuclear fuel could be part of a fissile material cut-off treaty, could serve as an additional measure for the IAEA safeguards system to monitor compliance with the Non-Proliferation of Nuclear Weapons Treaty, and could be an important verification tool of a reprocessing moratorium or Nuclear Weapon Free Zone in the Middle East or East Asia. Atmospheric transport modelling is applied to determine the area over which krypton-85 emissions from undeclared reprocessing activities at various levels in the Middle East would still be detectable against the high krypton-85 background from reprocessing in historical weapon programs in the United States and USSR as well as more recent and ongoing commercial reprocessing in France and the U.K. Analysis of annual wind flow over Israel's Dimona facility, the only operating reprocessing site in the region, suggests that a known reprocessing plant could be monitored with one or a few fixed monitoring stations. Random air sampling for krypton-85 analysis, perhaps using drones, may be feasible for reliable and timely detection of clandestine reprocessing plants against the krypton-85 background but would require on the order of 50–100 air samples per day. Ending reprocessing at La Hague in France and at Sellafield in the UK and the resulting decline of the krypton-85 background over time would reduce to about 10 the number of daily samples required to monitor the Middle East.