Security and Highly Enriched Uranium (HEU)

The Seoul Nuclear Summit, The National Interest,  Miles A. PomperMichelle E. Dover ,  January 4, 2012  “……. [In 2010] The White House announced that fifty-four national commitments were made by twenty-nine countries. These included pledges to donate money to the IAEA, remove or secure nuclear material, prevent nuclear smuggling, ratify or support existing conventions and treaties, and convert reactors from running on nuclear-weapons-usable highly enriched uranium (HEU) to safer low-enriched uranium (LEU).

The last promise was particularly important. Unlike its cousin, plutonium, HEU is suitable for use in the simplest kind of nuclear weapon, a so-called “gun-type” bomb. In gun-type devices, one subcritical piece of fissile material is fired at another subcritical target. Together they form a critical mass and spark a chain reaction. The process is so simple and well understood that such a device does not need to be explosively tested; even the first such bomb, which was dropped on Hiroshima in 1945, was not tested prior to its use. Terrorists who acquired a sufficient quantity of HEU would not need to be backed by the scientific and financial resources of a state to construct such a nuclear device.

The primary civilian use of HEU has been in research reactors and other test facilities, where it has been used in the process of producing medical isotopes and in civilian propulsion reactors. A half century ago, the Soviet Union and the United States started shipping HEU abroad as part of their peaceful nuclear-cooperation programs (“Atoms for Peace” in U.S. parlance) because it generates a high flow of neutrons, useful for research and a number of specialized tasks.

In the 1970s, the United States and the Soviet Union realized the potential proliferation problem of stockpiles of HEU fuel scattered around the world and began researching how to convert reactors to the use of LEU fuel. Russia later restarted the Soviet program, but it has been reluctant to convert its own reactors to LEU. After the September 11 attacks, the United States accelerated its efforts to secure HEU holdings around the world and convert facilities to LEU.

Conversion is not a simple process: LEU fuel cannot be introduced into a research reactor without significant changes to the reactor itself, similar to how cars cannot run on fuels which they were not designed to handle. Since it is expensive to change the core design completely (much like putting a new engine in an old car), engineers attempt to tinker with the reactor core to achieve the same performance while not altering the reactor’s basic dimensions or running costs. The challenge is particularly difficult given that research reactors are even less standardized than power reactors, meaning that almost every conversion of a reactor requires a time-consuming process to determine what changes can be made safely even before undertaking the years-long conversion process itself. However, these technical challenges pale next to the difficulty in motivating countries, particularly Russia, to undertake conversions. U.S. officials estimate that even after decades of effort, little more than one-third of the almost two hundred facilities worldwide that used HEU have been converted to LEU or shut down.

An April 2011 report by the Arms Control Association and the Partnership for Global Security concluded that roughly 60 percent of the 2010 commitments had been met, and substantial progress had been made on another 30 percent. Very few commitments had seen no progress at all. Ukraine, which was highly integrated into the Soviet nuclear complex, was suddenly left in the early 1990s with control of nuclear-weapons, energy and research programs, along with associated facilities and radioactive waste. While it transferred its weapons back to Russia in the 1990s, Ukraine still has nuclear-energy and research programs. It pledged to remove all of its HEU stocks by the 2012 Nuclear Security Summit, and today it has removed 50 kg of HEU fuel and 56 kg of spent HEU fuel from three sites. Thus, it is on track to fulfill its commitment. Outside of the summit, Ukraine has developed its legal and regulatory structures and accepted the United States’ help in strengthening its on-site security. Other states have continued to complete their promises to increase cooperation with international mechanisms such as the IAEA, the G-8 Global Partnership and the Global Initiative to Combat Nuclear Terrorism. They have also ratified related treaties and conventions, created new training and research centers, and physically secured or minimized the use of fissile material.

But other foreign-policy considerations can interrupt these efforts. Belarus, another former Soviet state with a substantial nuclear program, was not invited to attend the 2010 summit because it resisted pressure to give up its stockpile of HEU, but it pledged to the United States in December 2010 that it would ship its remaining weapons-grade HEU (nearly enough for two bombs) to Russia by the time of the 2012 summit. However, Minsk retracted that promise after the United States imposed sanctions on Belarus for cracking down on opposition leaders and cooperating with Iran’s nuclear program…..

http://nationalinterest.org/article/the-seoul-nuclear-summit-6284

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