|Fig. 1: The partially completed MOX plant at the Savannah River Facility in 2012. (Source: Wikimedia Commons)|
Weapon-grade Plutonium, unlike weapon-grade Uranium, cannot be blended with other materials to make it unusable in weapons. However, it can be fabricated into mixed oxide uranium-plutonium fuel, also known as MOX fuel, and irradiated in civil nuclear power reactors for electricity generation.  The spent fuel created from this process is significantly harder to use for weapons purposes, therefore in principle reducing the chance of proliferation. This logic provided the basis behind the Plutonium Management and Disposition Agreement (PMDA) signed by Vice President Gore and Russian Prime Minister Kasyanov in 2000. A landmark agreement between the countries, it committed both Russia and the United States to dispose of no less than 34 metric tons of surplus weapon-grade plutonium using the agreed upon MOX method. The 68 tons of plutonium would have provided enough material for 17,000 nuclear weapons. 
The U.S. effort entailed a commitment to construction of a Mixed Oxide Fuel Fabrication Facility at the Department of Energys Savannah River Site in Aiken, South Carolina (see Fig. 1). However, the U.S. effort has been plagued with large cost increases and schedule delays. Originally estimated to cost $4 billion, MOX construction began in 2007: as of fiscal year 2018, it is estimated to be only 70% complete with about $12 billion needed to finish it.  The Obama Administration began considering alternatives as early as 2013. The most attractive alternative was determined to the be the dilute and dispose method, which would down-blend the plutonium with an inert material for direct disposal in a repository (a process that could be implemented decades sooner than MOX with lower cost and fewer risks). The dilute and dispose method had estimated annual operation costs of $300-400 million as compared to the far more expensive $800 million-$1 billion estimated for the MOX fuel facility (after the hefty $30+ billion needed to construct the facility).  The large price tag for completion of the MOX facility - along with increasingly unstable relations with Russia and the fact that the deadline for completion kept getting pushed back - made the dilute and dispose option increasingly attractive to the U.S. Government.
Support for the project dwindled for these reasons, until in budget documents for fiscal year 2015, the Department of Energy placed the MOX facility in cold standby, meaning that work on the structure would be scaled back to activities such as protecting the facility and its equipment from the elements and keeping the site secure (preserving the site for potential use). The final straw came when the NNSA (National Nuclear Security Administration) testified before Congress in late 2016 that the Obama administration wanted to pull the plug on MOX and instead pursue the far more attractive dilute and dispose method.  Shortly thereafter, in an October 3, 2016 presidential decree, Russian President Vladimir Putin suspended the PMDA, citing "unfriendly actions" by the United States and the "inability" of Washington to fulfil its obligations under the agreement.  Russia argued that the new U.S. plan of "dilute and dispose" did not meet the terms of the deal because it would not change the composition of the plutonium (from weapons grade to reactor grade). Therefore, this would mean the diluted plutonium could still be retrieved and used again in weapons. The Department of Energy refutes this claim, arguing that the financial and technical effort required to retrieve the diluted plutonium would be prohibitive. Russia has publicly stated that it would consider the possibility of reactivation of the PDMA if the U.S. agreed to stick to the original disposal method (MOX). However, the Trump administration has followed in Obama's footsteps: the 2019 Department of Energy Budget Request for fiscal year 2019 asks for funding to close the Mixed Oxide Fuel Fabrication Facility at Savannah River and reaffirms the agency's preference for the dilute and dispose method. 
On the other hand, Russia is still on schedule for disposition of their plutonium (through the use of their BN-800 reactor, which went online in 2016), according to the 2010 re-negotiated terms of the PMDA.  The PMDA was supposed to be a landmark agreement between Russia and the US - the follow-up to the successful Megatons to Megawatts Program - cementing an era of cooperation between two nuclear states that could serve as role models to the rest of the world. However, the PMDA has failed to live up the hype and puts the future of any nuclear disarmament agreements in peril.
Paulette Wolak. The author warrants that the work is the author's own and that Stanford University provided no input other than typesetting and referencing guidelines. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
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