Alexander Glaser

Characteristics of the Gas Centrifuge for Uranium Enrichment and Their Relevance for Nuclear Weapon Proliferation

This article presents an analytical model, originally developed in the 1980s, for the gas centrifuge and uses this methodology to determine the main design and operational characteristics of several hypothetical centrifuge designs. A series of simulations for a typical first-generation machine is used to assess the relevance of important breakout scenarios, including batch recycling and cascade interconnection, using either natural uranium or preenriched material as feedstock.

A zero-knowledge protocol for nuclear warhead verification

The verification of nuclear warheads for arms control involves a paradox: international inspectors will have to gain high confidence in the authenticity of submitted items while learning nothing about them. Proposed inspection systems featuring ‘information barriers’, designed to hide measurements stored in electronic systems, are at risk of tampering and snooping. Here we show the viability of a fundamentally new approach to nuclear warhead verification that incorporates a zero-knowledge protocol, which is designed in such a way that sensitive information is never measured and so does not need to be hidden. We interrogate submitted items with energetic neutrons, making, in effect, differential measurements of both neutron transmission and emission. Calculations for scenarios in which material is diverted from a test object show that a high degree of discrimination can be achieved while revealing zero information. Our ideas for a physical zero-knowledge system could have applications beyond the context of nuclear disarmament. The proposed technique suggests a way to perform comparisons or computations on personal or confidential data without measuring the data in the first place.

From Brokdorf to Fukushima: The long journey to nuclear phase-out

Shortly after the accident at the Fukushima Daiichi Nuclear Power Station, Germany’s government started preparing legislation that would close the country’s last nuclear power plant by 2022. But this wasn’t an entirely new development: Germany had been planning to leave nuclear energy behind for decades, and to understand its nuclear phase-out requires a close look at the past. Several projects and events mark the beginnings of the German anti-nuclear power movement: Among them are the huge protests over the Brokdorf reactor, which began in 1976 and led to civil war-like confrontations with police, and the controversy over the Kalkar fast-neutron reactor in the mid-1970s. Because of these and subsequent developments—including the 1986 Chernobyl accident—by the 1990s, no one in German political life seriously entertained the idea of new reactor construction. This tacit policy consensus led to energy forecasts and scenarios that focused on energy efficiency, demand reduction, and renewable energy sources. By the time of the Fukushima accidents, many of these new energy priorities had already begun to be implemented and to show effect. Replacing nuclear power in Germany with other energy sources on an accelerated schedule is likely to come with a price tag, but, at the same time, Germany’s nuclear phase-out could provide a proof-of-concept, demonstrating the political and technical feasibility of abandoning a controversial high-risk technology. Germany’s nuclear phase-out, successful or not, may well become a game changer for nuclear energy worldwide.

Balancing risks: nuclear energy & climate change

First, nuclear power could make a signi1⁄2cant contribution to climate change mitigation. To do so, however, nuclear power would have to be deployed extensively, including in the developing world. A “one-tier” world will be required– that is, a world with an agreed set of rules to govern nuclear power that are the same in all countries. Second, the world is not now safe for a rapid global expansion of nuclear energy. Nuclear-energy use today relies on technologies and a system of national governance of the nuclear fuel cycle that carry substantial risks of nuclear weapons proliferation. There are still more than 20,000 nuclear weapons in the world, and in the current international system, nations see these weapons as instruments of power and sources of prestige. These nations have competing interests and long-standing conflicts. There are also subnational groups that resort to force. The risks that a global expansion of nuclear power will facilitate nuclear proliferation and incidents of nuclear terrorism, or even lead to regional nuclear war, are signi1⁄2cant. Nuclear war is a terrible trade for slowing the pace of climate change. Third, a world considerably safer for nuclear power could emerge as a co-bene1⁄2t of the nuclear disarmament process. The national-security community is currently engaged, to an unprecedented degree, in seeking progress toward nuclear disarmament. A by-product of this process could be different technology choices and innovations in the governance of nuclear power–notably, a halt to spentfuel reprocessing to separate plutonium as well as multinational ownership and control of uranium enrichment facilities. These developments could begin to decouple nuclear power from nuclear weapons. Finally, the next decade is critical. While several approaches to climate change mitigation are available for immediate, rapid scale-up, nuclear power could be so in maybe 10 years, provided the coming decade is used to establish adequate technologies and new norms of governance. Nuclear power ought to be deployed seriously as a mitigation strategy only when and if it can provide a sustainable contribution. The world will not bene1⁄2t if nuclear power’s contribution is withdrawn a decade or two after global scale-up begins, as a result of flaws related to its coupling to nuclear weapons.

The gas centrifuge and nuclear weapons proliferation

Uranium enrichment by centrifugation is the basis for the quick and efficient production of nuclear fuel—or nuclear weapons.

Weapon-Grade Plutonium Production Potential in the Indian Prototype Fast Breeder Reactor

India is building a 500 MWe Prototype Fast Breeder Reactor, which is scheduled to be operational by 2010. India has refused to accept international safeguards on this facility, raising concerns that the plutonium produced in its uranium blankets might be used to make nuclear weapons. Based on neutronics calculations for a detailed three-dimensional model of the reactor, we estimate that up to 140 kg of weapon-grade plutonium could be produced with this facility each year. This article shows how Indias large stockpile of separated reactor-grade plutonium from its unsafeguarded spent heavy-water reactor fuel could serve as makeup fuel to allow such diversion of the weapon-grade plutonium from the blankets of the fast breeder reactor. We describe and assess the most plausible refueling strategies for producing weapon-grade plutonium in this way.

On the Proliferation Potential of Uranium Fuel for Research Reactors at Various Enrichment Levels

This article reviews the rationale of selecting an enrichment of just less than 20% (low-enriched uranium) as the preferred enrichment level for research reactor fuel in order to minimize overall proliferation risks. The net strategic value of the nuclear material associated with reactor operation is evaluated for a variety of enrichment levels, ranging from slightly enriched to weapon-grade fuel. To quantify the proliferation potential, both the demand of fresh uranium fuel as well as the plutonium buildup in the irradiated fuel are estimated via cell burnup calculations. The analysis confirms the usefulness of the current enrichment limit and challenges a recent trend to reconsider fuel enrichment levels between 20% and 50% for new research reactor projects.

Proliferation risks of magnetic fusion energy: clandestine production, covert production and breakout

Nuclear proliferation risks from magnetic fusion energy associated with access to weapon-usable materials can be divided into three main categories: (1) clandestine production of weapon-usable material in an undeclared facility, (2) covert production of such material inn a declared facility, and (3) use of a declared facility in a breakout scenario, in which a state begins production of fissile material without concealing the effort. In this paper we address each of these categories of risks from fusion. For each case, we find that the proliferation risk from fusion systems can be much lower than the equivalent risk from fission systems, if the fusion system is designed to accommodate appropriate safeguards.

Isotopic Signatures of Weapon-Grade Plutonium from Dedicated Natural Uranium–Fueled Production Reactors and Their Relevance for Nuclear Forensic Analysis

Abstract We report neutronics calculations for the most important natural uranium–fueled reactor types historically used for weapons plutonium production. These include an early design of the Hanford-type graphite-moderated and light-water-cooled reactor used in the United States; the Calder Hall–type graphite-moderated and gas-cooled reactor used in the United Kingdom; and the NRX-type heavy-water-moderated and light-water-cooled reactor, originally developed in Canada for civilian purposes but later used in India and Pakistan for military plutonium production. We show that while it is possible in principle to identify with a high level of confidence weapon-grade plutonium compositions produced in other types of reactors, e.g., light-water-cooled or fast neutron reactors, it is difficult to distinguish among plutonium compositions generated in dedicated production reactors fueled with natural uranium. This suggests that efforts to determine the origin of weapon-grade plutonium for a nuclear forensic analysis could well remain inconclusive without access to databases based on actual samples of the nuclear material.

The Conversion of Research Reactors to Low-Enriched Fuel and the Case of the FRM-II

The use of highly enriched uranium (HEU) as fuel in research reactors runs contrary to the concept of proliferation-resistant nuclear technologies. Consequently, for more than two decades, international activities have been undertaken to terminate the use of HEU in research reactors by supporting the conversion of these facilities to low-enriched uranium (LEU). Achievements, setbacks and perspectives of these efforts are discussed in this article. The German research reactor FRM-II, which will presumably begin operation in 2002, would be the worlds first HEU-fueled reactor in more than 10 years. Among proponents and critics of HEU use in this reactor there is disagreement on the scientific impact of FRM-II conversion, which could be based on designs proposed by Argonne National Laboratory (ANL). In order to support the decision-making process, independent computer simulations have been performed that provide detailed information on the scientific usability of the converted reactor. The most important results of these calculations are presented and discussed.