Test Ban Research Articles

The entanglement of fusion energy research and bombs

ABSTRACT The recent achievement of fusion ignition—meaning more energy came out of a self-sustaining fusion reaction than was put in—at Lawrence Livermore National Laboratory’s National Ignition Facility has brought to the fore long-simmering questions about whether certain experiments violate the Comprehensive Test Ban Treaty on nuclear explosions. Fusion research for peaceful use and military use are highly intertwined, despite attempts to cloak nuclear weapons with the aura of the so-called “peaceful atom.” Ignition has been achieved, but there is still a remarkable silence around whether pure fusion weapons—weapons that could kill large numbers of humans with neutron radiation but have blast effects much smaller than current thermonuclear weapons—are an objective of the overall program. Even if not an explicit objective, would they be built if fusion technology makes them feasible?

Computational Optimization of 133m Xe Production in the Washington State University TRIGA Reactor

Here we present a new method of irradiating 132Xe capsules with neutrons to produce 133mXe gas standards that are used for radiation detector calibration at radioxenon measurement laboratories in support of the Comprehensive Test Ban Treaty (CTBT). This method is designed to maximize the production of 133mXe compared to 133Xe, both of which are competing products from the 132Xe(n, g) reaction. The 133mXe is produced at a much higher fraction for high-energy neutron absorptions in 132Xe (~50% for fast neutrons versus ~11% for thermal neutrons). We performed “spectral tuning” of the Washington State University (WSU) TRIGA reactor neutron spectrum inside the 132Xe ampules to maximize the number of fast neutrons and minimize the number of thermal neutrons available for 132Xe absorption. Spectral tuning analysis, done with Monte Carlo simulations, provided valuable insights into a future final design for a 132Xe irradiation capsule. With no spectral tuning, the fractional yield of 133mXe in the WSU reactor was ~11.7%. By surrounding the 132Xe capsule with a 0.5-cm-thick layer of tungsten and a 2.83-cm layer of europium (III) oxide and placing it in the reactor’s cadmium rotator tube next to the fuel elements, the fractional yield of 133mXe can be increased to 24.6%, a 111% increase in yield. Thus, by improving the fractional yield of 133mXe through spectral tuning, the CTBT will have better quality gas standards to use for radioxenon detector calibration to assist in the CTBT’s mission.

BIKINI ATOLL, NEVADA, MOSCOW. WASHINGTON’S LONG ROAD TO THE PARTIAL TEST BAN TREATY (1958–1963)

The conclusion of the 1963 Moscow Treaty banning nuclear weapon tests in the atmosphere, in outer space and under water is an important milestone in the history of the Cold War. It was preceded by long and complex negotiations between the USSR and the US. Measures to impose a moratorium on tests (August 1958 — August 1961) did not yield signifi cant results either in reducing harmful environmental consequences or in reducing the risk of nuclear conflict. In addition, the issue of at least partial test ban was closely linked to the political contradictions between the superpowers, in particular, regarding the status of Berlin. On 9 September 1961, the negotiations were stopped. In the fall, the USSR conducted a large series of explosions, and advances in weapons development required new tests. Moscow’s decision to withdraw from the moratorium was dictated by the desire to demonstrate to its opponents the readiness for any emergency. In 1962, the events around Cuba led not only to intensified testing by both powers, but also to the acute Cuban Missile Crisis in October, when the danger of using nuclear weapons became quite real. The August 1963 treaty was one of the immediate outcomes of the Cuban Missile Crisis. However, it is also important that the superpowers came to the signing of the Moscow Treaty only after their scientific and technological achievements (including, above all, the results of nuclear tests) had been able to ensure a confident strategic deterrence of each other. The tests of nuclear devices conducted by both powers in 1961 and 1962 allowed them to equip all types of carriers with warheads as part of their planned programs to renew strategic nuclear arsenals. At the same time, the Moscow Treaty created a basis for harmonizing the positions of the US and the USSR with regard to nuclear nonproliferation for many years to come.

British Nuclear Weapons and the Test Ban: Squaring the Circle of Defence and Arms Control, 1974–82 by John Walker (review)

British Nuclear Weapons and the Test Ban: Squaring the Circle of Defence and Arms Control, 1974–82 by John Walker (review)

Inferring the Focal Depths of Small Earthquakes in Southern California Using Physics-Based Waveform Features

ABSTRACT Determining the depths of small crustal earthquakes is challenging in many regions of the world, because most seismic networks are too sparse to resolve trade-offs between depth and origin time with conventional arrival-time methods. Precise and accurate depth estimation is important, because it can help seismologists discriminate between earthquakes and explosions, which is relevant to monitoring nuclear test ban treaties and producing earthquake catalogs that are uncontaminated by mining blasts. Here, we examine the depth sensitivity of several physics-based waveform features for ∼8000 earthquakes in southern California that have well-resolved depths from arrival-time inversion. We focus on small earthquakes (2<ML<4) recorded at local distances (<150 km), for which depth estimation is especially challenging. We find that differential magnitudes (Mw/ML–Mc) are positively correlated with focal depth, implying that coda wave excitation decreases with focal depth. We analyze a simple proxy for relative frequency content, Φ≡log10(M0)+3log10(fc), and find that source spectra are preferentially enriched in high frequencies, or “blue-shifted,” as focal depth increases. We also find that two spectral amplitude ratios Rg 0.5–2 Hz/Sg 0.5–8 Hz and Pg/Sg at 3–8 Hz decrease as focal depth increases. Using multilinear regression with these features as predictor variables, we develop models that can explain 11%–59% of the variance in depths within 10 subregions and 25% of the depth variance across southern California as a whole. We suggest that incorporating these features into a machine learning workflow could help resolve focal depths in regions that are poorly instrumented and lack large databases of well-located events. Some of the waveform features we evaluate in this study have previously been used as source discriminants, and our results imply that their effectiveness in discrimination is partially because explosions generally occur at shallower depths than earthquakes.

Seismic Discrimination Between Nuclear Explosions and Natural Earthquakes using Multi-Machine Learning Techniques

AbstractIn the field of seismic signal analysis, it is of utmost importance to accurately differentiate between earthquakes and underground nuclear explosions. As a contribution for the verification regime of the Comprehensive Nuclear Test Ban Treaty (CTBT), Various methods have been employed for this purpose, including Complexity, Spectral ratio, mb—Ms (body wave and surface wave magnitudes), and corner frequency of P and S waves. These discrimination techniques have been examined to manually identify natural seismic events from nuclear explosions across different regions worldwide, such as China, India, Pakistan, North Korea, and the United States. To gather the necessary data, a comprehensive dataset comprising nuclear explosions and earthquakes of the same magnitude range (4 ≤ mb ≤ 6.5) of 35 seismic events from 1945 to 2017 has been compiled from the International Research Institute for Seismology (IRIS) using broadband and long period seismic stations. The objective of this study is to employ a range of linear and nonlinear Machine Learning (ML) models with the aim of automatically distinguishing between underground nuclear explosions and large earthquakes to enhance the accuracy of manual feature extraction. For this purpose, time domain waveforms and different classifier techniques focused on feature extraction have been used. The ML models employed include logistic regression, K-nearest neighbours classifier, decision tree classifier, random forest classifier, voting classifier, and Naive Bayes. The outcomes of the ROC and AUC analyses were employed to validate the validity of our proposed discrimination algorithm. The results show that the Random Forest Classifier is the most effective model, obtaining 100% accuracy in the case of feature extraction, while the best model for the time domain waveform classifier that achieved 75.5% accuracy is the voting classifier.

India’s Chequered Relationship with the Comprehensive Test Ban Treaty: Examining Cross-Linked Concerns over Nuclear Disarmament and National Security

In 1994, India enthusiastically supported the United Nations process for negotiating the Comprehensive Test Ban Treaty (CTBT). It expected the treaty would ban all types of nuclear testing and pave the way for nuclear disarmament. The final treaty negotiated in 1996 did not commit itself to this goal of disarmament and India ultimately rejected it. However, behind this rejection also lies the story of India’s deteriorating national security outlook and decision-makers’ keen desire to avoid their country being subjected to a discriminatory nonproliferation regime enacted by the nuclear weapon states. The key questions guiding the query on (CTBT) are: What were the reasons behind India’s initial support of the CTBT in 1993? And what transpired between 1994 and 1996 that led India to change its stand?

Relocation of 3 April 2017 Moiyabana Earthquake in Botswana Using Seismological Data from Local Network of Autonomously Recording Seismographs and International Monitoring System Stations

AbstractOn the 3rd April 2017 a widely felt Moiyabana earthquake shook Botswana and the rest of southern Africa. Previous Moiyabana earthquake locations used mainly teleseismic or regional seismograms; and/or non-seismic methods which include Synthetic Aperture Radar (InSAR), and magnetotelluric (MT). These results did not agree, as evidenced by the depth of the earthquake that ranged from zero to 30 km (i.e. indicating either a man-made event or a natural event); thus motivating us to re-assess the location parameters. Unfiltered seismic waveform data from the recent project of the Network of Autonomously Recording Seismographs (NARS) in Botswana was complimented with stations from the International Monitoring System (IMS) to relocate the event. Relocated parameters are origin time, epicentre, focal depth, and magnitude. Geotool software from the Comprehensive Nuclear Test Ban Treaty Organization (CTBTO), and the Regional Seismic Travel Time model (RSTT) were used to process vertical components waveforms from 9 NARS and 32 IMS stations. Geotool results are: earthquake epicentre (22.645 °S: 25.220 °E); origin time of 17:40:16.9 (UTC); hypocentral depth range of 22 to 24 km; body magnitude (mb) and local magnitude (ml) of 6.3 ± 0.6 and 6.0 ± 0.8, respectively. RSTT results are: earthquake epicentre (22.667 °S: 25.257 °E); origin time of 17:40:16.95 (UTC); hypocentral depth of 25 km; and mb of 6.65 ± 0.03. The seismological location parameters from Geotool and RSTT, agree very well within experimental uncertainties with the non-seismic geophysical methods.

Preserving the nuclear test ban after Russia revoked its CTBT ratification

ABSTRACT Russia’s withdrawal of its ratification of the Comprehensive Nuclear Test Ban Treaty in 2023 raised concerns about the possible end of the existing moratorium on nuclear explosions. But the moratorium continues to hold, largely thanks to the de facto norm against full-scale nuclear tests and the strength of institutional structures created by the treaty. Transparency of nuclear experiments demonstrated by the United States will be an important factor in upholding the moratorium, and Russia and China should be encouraged to be more transparent about their activities as well. Any disputes about the exact nature of their experiments and their adherence to the strict definition of a zero-yield nuclear explosion should not become reasons to question the value of the moratorium—or the ability of parties to verify and enforce the test ban once the treaty comes into force.

New confidence-building measures can reduce tensions around subcritical tests

ABSTRACT With rising tensions between the United States on one side, and China and Russia on the other, the three countries have grown mutually accusatory about some testing activities they conduct to maintain and modernize their nuclear arsenals, with allegations made by the United States focusing on very low-yield fission experiments. In a world where trust in the nonproliferation regime is weakening and most bilateral arms control measures have been suspended, many experts fear that recriminations over very low-yield tests could spark a new escalation spiral to full-scale nuclear tests. Transparency measures could diffuse the suspicions around these tests and strengthen the Comprehensive Nuclear Test Ban Treaty, which is largely being complied with but still not legally in force.

The logic for US ratification of the Comprehensive Nuclear Test Ban Treaty

ABSTRACT The United States has accepted increasingly stringent limits on nuclear testing, culminating in the 1996 Comprehensive Nuclear Test Ban Treaty. However, the US Senate in 1999 failed to consent to ratification, given concerns about verifying the treaty and maintaining safe and reliable US nuclear weapons without testing. Since then, the US Stockpile Stewardship Program has matured and allowed certification that US nuclear weapons remain safe and reliable without nuclear explosive testing. Likewise, advances in the US Nuclear Detonation Detection System and the International Monitoring System make virtually all tests detectable. Bringing the Comprehensive Nuclear Test Ban Treaty into force is in the US interest, as it would lock in an American advantage in nuclear knowledge and expertise and hinder other states from developing more sophisticated nuclear arms. Unfortunately, however, American domestic politics and the difficult international environment make it unlikely that the treaty will enter into force in the near term.

Development and Operation of a Global‐Scale Seismographic Network: The IRIS/USGS GSN

AbstractFrom inception in the late 1980s up to the present, the Global Seismographic Network has produced high quality seismic data that has advanced research into the structure of the Earth's deep interior particularly the large‐scale heterogeneous elastic/anelastic structure of the mantle and core. The network's breadth of coverage enables images of great earthquakes impossible to obtain from regional networks or array data alone. Analysis of the data has provided new insights into non‐traditional seismic sources such as slow earthquakes, glaciers and landslides. Ancillary meteorological and infrasound sensors collocated at the sites support unique studies of volcanic events such as the recent eruption of the Hunga Tonga–Hunga Ha'apai volcano. Near real‐time transmission of the data to hazard warning centers has expanded the network's usefulness as a tool for rapid response to earthquakes, for warning communities effected by tsunamis, and for monitoring compliance with nuclear test ban treaties. The successful construction and operation of the network would not be possible without the outstanding international cooperation of many governmental, academic and private groups who have hosted components of the network.

Using sensors of opportunity to estimate the density of blue and fin whales

The “Combining global OBS and CTBTO recordings to estimate abundance and density of fin and blue whales”, or CORTADO project, is using data from two bottom-sensor types to implement a suite of methods for estimating density of fin and blue whales. While previous studies have demonstrated the utility of Ocean Bottom Seismometers (OBS) and Comprehensive Test Ban Treaty Organization (CTBTO) hydroacoustic data, the techniques have not yet been developed to the point where they can be routinely applied by the wider research community. The primary CORTADO goal is to provide a set of software tools and training materials to expand access and usability of large, historic datasets. This talk will focus on using the CTBTO sensors for estimating density with a bearing method. This technique uses the bearing of and the signal-to-noise ratio for each detected call to estimate how many animals are producing a set of calls at any given time over the detection range of the sensor at all bearings. Applying this tool to several CTBTO sensors, we can compare the amount of blue and fin whales over time as well as spatially across the northern and southern coverage areas of the sensor array.

A comparison of tidal components across multiple sites using ultra-low frequency ocean acoustic measurements

Recent long-term analysis of the hydrophone measurements taken in the deep sea reveals indications of multiple tidal components. Tidal harmonics corresponding to solar and lunar diurnal and semi-diurnal tide components were determined by analyzing the Cepstrum (variance of a spectral power) of the year or more long time series (0.5 Hz) of mid-water column measurements taken by the United Nations Comprehensive Test Ban Treaty Organization (CTBTO) in the Pacific, Atlantic and Indian Ocean. Postulations for the origin of this signal include rolling rocks, ocean turbulence, a change in the surface height, currents, mechanical/electrical (non-acoustic) noise and wind/wave induced noise propagating in the ocean. In this paper, this work is extended to more sites and encompasses a larger portion of the ultra-low frequency range (i < 5 Hz). it is found that different sites have quite different tidal components (as expected) but also have different frequency components (some with 0.5–1 Hz and others with 3–5 Hz). This opens the possibility of acoustic soundscape differences between sites due to regional source generation and local acoustic propagation.

Q&A Aftab Khan, a career in geophysics

Abstract Sue Bowler talks to Aftab Khan, who recently celebrated his 90th birthday, about his career in geophysics, from the origins of the modern subject, through the exploration of the African Rift Valley and the steps to a nuclear test ban treaty

Влияние Индии на формирование многополярного ядерного порядка

India’s decision not to join the Nuclear Non-Proliferation Treaty and the Comprehensive Test Ban Treaty has led to its labelling as a state that is not fully aligned with the global nuclear order. This places it in the same category as other nuclear-armed countries outside these agreements, such as Israel, North Korea, and Pakistan. India’s nuclear weapons testing in 1998, followed by a similar move by Pakistan, has been viewed as a challenge to international security and the nuclear non-proliferation regime. This article aims to examine India’s stance on these treaties and its choice to become a nuclear-armed state in 1998 within the context of its efforts to influence the establishment of a fair global order that serves the interests of not only the major nuclear powers (USSR/Russia, Great Britain, China, the United States, and France) and their allies, but also the rest of the world. Delhi’s actions in the realm of nuclear arms control highlights the emerging multipolar world. Although India has refrained from actively participating in disarmament negotiations after the end of Cold War, its previous experiences remain relevant today. The breakdown of the U.S. – Russia nuclear arms control as well as crises over the nuclear non-proliferation and testing banning regimes have given weight to the arguments put forth by Indian leaders and diplomats. These arguments emphasize the urgency of reducing nuclear risks and exercising strategic restraint, including maintaining a moratorium on nuclear testing. Since 1998, India has adopted an approach different from its previous policy on various nuclear disarmament issues. This shift is evident in the country’s solidarity with other nuclear powers in opposing the 2021 Treaty on the Prohibition of Nuclear Weapons. However, India’s longstanding support for multipolarity in international security policy, particularly regarding nuclear weapons, remains unchanged.

Analysis of Nuclear Explosion Detection Capability of IMS Hydroacoustic Network

The Comprehensive Nuclear Test Ban Treaty (CTBT) organization has established a hydroacoustic network to ensure the effective detection of nuclear explosions in the vast ocean and in the atmosphere over it in order to effectively guarantee the implementation of the treaty. To assess its effectiveness, according to the reciprocity of underwater acoustic field, this study employs the hydrophone position as the central sound source and utilizes the parabolic equation, along with seabed topography and sound velocity profile data, to estimate the transmission loss. Background noise levels of station evaluation are conducted by using historical data so as to estimate the underwater nuclear explosion sound source level via a passive sonar equation. Utilizing the full ship shock trial (FSST) results of the “Ford” aircraft carrier on June 18, 2021, as a case study, the detection capability of the HA10 station for nuclear explosions is investigated. Subsequently, the network’s overall detection capability was evaluated using the source level at 20 Hz corresponding to a 1 kiloton nuclear explosion yield as a reference. Findings indicate the network’s proficiency in identifying long‐distance propagation signals, particularly those with high explosion source levels within the sound fixing and ranging (SOFAR) channel. The sensitivity analysis demonstrates the network’s ability to detect explosions smaller than 1 kg equivalent in close proximity to a station, and larger explosions exceeding 1 kg or 1 ton at greater distances. This evaluation underscores the network’s significance in detecting and monitoring underwater nuclear explosions across extensive oceanic regions.

Tidal modulation of very-low-frequency and ultra-low-frequency ambient noise levels.

Several years of continuous low-frequency underwater ambient noise data from 0.1 to 125 Hz have been made available for examination by the United Nations Comprehensive Nuclear Test Ban Treaty Organization. Narrow-band noise time records between 0.5 and 10 Hz were selected for study, chosen deliberately to address noise sources tied primarily to the environment. Power spectra of the variable narrow-band time records were found to display sharp spectral lines at fluctuation frequencies that match lunar and solar diurnal and semidiurnal ocean tides.

Algorithm development for low level radioxenon 2D spectra analysis: A first case of study using spectral unmixing for a β-γ detector

In the scope of the verification regime of the Comprehensive nuclear Test Ban Treaty, the CEA/DAM is developing new β-γ measurement systems. In order to improve the analysis methods at low statistics, a new multiplicative spectral unmixing algorithm for full-spectrum analysis was tested on a particular setup for different types of mixtures. The reconstructed activities for simulated spectra and the characteristic limits found with this algorithm are compared to the classic ROI analysis method.

Моделирование нисходящего переноса 210Pb на примере естественного торфяника Иласского болотного массива Европейской Субарктики России: модель IP-CRS

The paper presents the results of the modelling of the transport of 210Pb down the peat core for the Ilassky natural bog massif. The activities of radionuclides 210Pb and 137Cs were investigated in the core layer by layer. Due to the nonexponential decrease of 210Pb activity, significant errors are possible in determining the age and accumulation rates of peat when applying classical dating models. The article presents 210Pb dating data obtained using the IP-CRS model. Data analysis showed that the vertical distribution of 137Cs and 210Pb is related to peat parameters: ash content and bulk density. The 210Pb dating of the core showed an age of 1963 for a depth of 17—19 cm, which is consistent with the 137Cs data. The dating of this horizon is indirectly confirmed by the data of the ash content and bulk density of peat. The above mentioned confirms the correctness and adequacy of the chosen model of dating of the natural peat bog. The peak of anthropogenic radionuclide content in peat deposits corresponds to 1963, the date of signing the Partial Nuclear Test Ban Treaty, being a reference point for geochronological studies. The results of linear accumulation rate, peat deposit mass accumulation rate and the magnitude of the atmospheric flux of 210Pb presented in the study are in good agreement with the data on peatlands of Northern Europe and the European Subarctic of Russia.