An Estimate of North Korean HEU Stockpile for the Given Natural Uranium Reserve and Enrichment Capacities

Abstract:

One of the greatest threats to world peace and security is the prospect of nuclear weapons in the wrong hands. Although the likelihood of a large-scale military conflict with nuclear weapons seemingly decreased with the end of the cold war, the threat posed by nuclear proliferation continues to persist. Indeed, nuclear proliferation remains a critical global problem that challenges vital national security interests of the United States (U.S.). This is partly due to the fact that the proliferation of nuclear weapons may endanger armed forces and military bases outside the U.S., threaten allies and friendly states of the U.S. and also complicate – if not undermine – the possibility of U.S. military intervention abroad. North Korea’s nuclear program poses particularly acute threats to the U.S. and its allies in East Asia.

Several studies have been conducted to understand North Korea’s nuclear weapons assets and capabilities. Based on the information available on their nuclear facilities, it is expected that North Korea has two types of nuclear weapons based on plutonium and uranium. The stockpile of plutonium was investigated by D. Albright and P. Brannan in 2007. This report presented the estimated operating histories of nuclear facilities such as nuclear reactors and radiochemistry laboratories that were used for producing plutonium. The expected plutonium stockpile in 2007 was between 46 to 64 kilograms. Between 28 to 50 kilograms of that were separated and available for use in nuclear weapons. An updated assessment by Albright in 2015 estimated that North Korea has between 30 to 34 kilograms of usable plutonium. A decrease of expected stockpile from 2007 to 2015 is probably caused by the nuclear tests on May 25, 2009 and February 12, 2013.

The expected uranium stockpile was also investigated. The stockpile of high-enriched uranium (HEU) was estimated and reported in 2015 based on two different scenarios. The first scenario assumed two centrifuge plants operating the first plant operated with a capacity of 2000-3000 P2-type centrifuges between 2005 and 2010 to produce HEU and second plant with 2000 P2-type centrifuges until 2014 produced LEU, which could have been misused to produced HEU after 2014. The second scenario is when North Korea operated 2000 P2-type centrifuges between 2010 and 2011 to produce LEU but subsequently misused to produce HEU. The median value for the first scenario is 240 kg and for the second scenario is 100 kg. According to a report published by the Center for International Security and Cooperation at Stanford University, around 6,000 centrifuges were operated in 2015 in North Korea. Based on this information, approximately 100 kilograms of the HEU could be produced per year. Then, by 2017, an additional 2,000 centrifuges are estimated to be clandestinely installed. With this addition, the total expected yield of HEU will be between 130 to 150 kilograms per year.

The estimated HEU stockpiles have varied widely due to the accessibility to the data such as installed number of centrifuges and their associated Separative Work Unit (SWU) capacity Therefore, in this study, the expected HEU stockpile will be reevaluated in the case of North Korea based on new information available in literature. The results of this study could help U.S. policymakers achieve better outcomes in future negotiations with North Korea.