As the United States reestablishes large-scale plutonium pit production, federal agencies have published environmental impact studies estimating radiological consequences from major facility fires in New Mexico and South Carolina. These analyses predict average latent cancer fatalities in the single digits but do not evaluate total cancers or remediation costs from land contamination. Using atmospheric transport and dispersion modeling, this study independently estimates downwind plutonium deposition and inhalation, cancer risk, and land contamination across meteorological conditions for different source terms. For assumptions consistent with current federal analyses, a 1-kilogram respirable release could produce up to 21 latent cancer fatalities, with total cancers three times higher. Tens of square kilometers of land could require billions of dollars in soil remediation, while contamination in residential areas could require evacuation. Larger releases involving different fire conditions and smaller particle sizes could cause over 1,000 fatalities, suggesting current assessments may underestimate accident consequences.
This paper reviews the technical issues underlying space-based boost-phase missile defense and examines the current technology available for space-based interceptors and the characteristics of the missiles such a system would face. It then analyzes a particular space-based missile defense system that has been proposed to intercept in boost, ascent, and midcourse phases to illustrate the details of such an analysis and the constraints imposed on such systems by the physics of operating in space.
This work considers the direct use of 60%-enriched uranium in pure fission nuclear weapons. From numerical simulations and simple analytics this work shows that substituting a weapons-grade core for a 60%-enriched core reduces the yield by a factor of 4 to 5 that is fairly insensitive to classified design details. A weapon designed to achieve a nominal 10 kt yield using weapons-grade uranium could therefore still produce a modest yield of 2-3 kt using a core of lower enrichment.
Since North Korea left the Treaty on the Nonproliferation of Nuclear Weapons in 2003, its nuclear fuel cycle has continued to operate and develop further, without transparency to international inspectors. A recent addition is the Experimental Light Water Reactor that started operation in October 2023. One concern is that this reactor may be used to produce plutonium for nuclear warheads, in addition to or instead of being used for electricity production. In this work, fissile material production in the new reactor is explored by modeling a possible core design and integrating information from available remote monitoring, such as satellite imagery of cooling water outlets from the facility. The results indicate that running the reactor with an initial enrichment of 1.75% or lower could potentially produce up to 20 kg of weapons-grade plutonium annually, substantially increasing North Korean plutonium production.
We present an imaging system that employs zero-knowledge protocols to protect sensitive geometrical information, along with procedures to increase confidence in the result. The goal of this work is to enable the inclusion of warhead confirmation measurements in future arms control treaties. We present a demonstration of both true positive and true negative measurements that validate models and establish authenticating procedures toward meeting acceptance requirements for use in nuclear facilities. We use a two-dimensional time-encoded fast neutron imaging system with an anti-symmetric mask pattern; the fast neutron count values exceeding minimum or maximum thresholds indicate that two measured items are not identical. Laboratory measurements over twenty trials show that alarm rates for negative confirmation measurements are within uncertainties of model predictions. Positive confirmation measurements indicate that alarm rates are large enough to encourage treaty compliance.
