The NSC document describing the initiative called for a U.S. interagency effort, with the NSC coordinating U.S. activities to secure and remove vulnerable nuclear materials worldwide. DOE has the largest agency role in undertaking initiative-related activities. Several offices within DOE and other U.S. agencies and agency offices are also involved in the initiative. Specifically, DOE’s Global Threat Reduction Initiative (GTRI) program works to reduce and protect vulnerable nuclear material located at civilian sites worldwide. In particular, it has programs to remove or confirm the disposition of excess HEU and plutonium, including U.S.-origin and material of other country origin, and convert research reactors and isotope production facilities to the use of LEU and nonweapons- usable materials. GTRI focuses primarily on the initiative’s key activities of removing and disposing of HEU and plutonium and converting reactors and isotope production facilities to the use of nonweapons-usable material. DOE’s Material Protection, Control and Accounting (MPC&A) program works with Russia, other former Soviet states, and other partner countries to improve the security of nuclear weapons and HEU and plutonium at their source and to promote nuclear security best practices. With respect to the initiative’s key activities, MPC&A is responsible for verifying the downblending of HEU in Russia to LEU and for upgrading the physical protection of HEU and plutonium. DOE’s Office of Nonproliferation and International Security coordinates interagency physical protection visits to partner countries holding key quantities of U.S.-origin HEU and plutonium to assess sites’ security status and ensure that the physical protection measures afforded U.S.-obligated material meet international physical security guidelines. DOE’s Office of Intelligence and Counterintelligence, both a DOE component and a member of the Intelligence Community, works with U.S. agencies and the Intelligence Community to combine reporting into and manage the Nuclear Materials Information Program (NMIP), an interagency effort that provides, among other things, information regarding the location, quantities, and vulnerabilities of sites storing HEU and plutonium worldwide. DOE’s Office of Environmental Management works to complete the safe cleanup of the environmental legacy brought about from five decades of nuclear weapons development and government- sponsored nuclear energy research. This effort contributes to the initiative’s key activity of removing HEU and plutonium to secure locations in the United States. State manages nuclear nonproliferation programs, supports the nuclear nonproliferation programs of other U.S. agencies working overseas, and conducts bilateral and multilateral diplomacy to address proliferation threats around the world under the Bureau of International Security and Nonproliferation. State’s primary contribution to the initiative’s activities includes fostering bilateral and international cooperation toward initiative objectives. DOD’s Cooperative Threat Reduction program works to eliminate and prevent the proliferation of weapons of mass destruction. The program contributes to the initiative’s key activities of removing and securing HEU and plutonium and upgrading the physical protection of HEU and plutonium by facilitating the safe and secure transport and storage or elimination, among other things, of nuclear weapons and weapons-usable nuclear materials. NRC regulates the export of nuclear materials, including HEU and plutonium, through licensing, inspection, and enforcement of its requirements. NRC’s licensing for the export of U.S. nuclear equipment and HEU and plutonium is conditioned on the partner country maintenance of adequate physical security measures, international safeguards, and other relevant criteria. NRC, as a member of the U.S. interagency group, is involved in the planning and implementation of physical protection visits to facilities holding or requesting to receive U.S.-obligated nuclear materials. The framework for accomplishing the goals of the initiative includes U.S. laws, agency regulations and programs, and international and bilateral commitments. Through this framework, the United States works with other countries to monitor and ensure the physical security of nuclear materials abroad, and, where feasible, to facilitate the removal of vulnerable nuclear materials. The United States works with other countries primarily within the framework of the IAEA, U.S. nuclear cooperation agreements, U.S.-Russia agreements, and U.S. fuel and nuclear material return programs. A description of each of these areas follows: IAEA: IAEA plays a key role in supporting international efforts to ensure the security of nuclear materials in a number of ways. IAEA’s international physical security guidelines provide the basis by which the United States and other countries generally classify the categories of protection that should be afforded special nuclear material, based on the type, quantity, and enrichment of the nuclear material. For example, Category I nuclear material is defined as 2 kilograms or more of unirradiated or “separated” plutonium or 5 kilograms of uranium-235 contained in unirradiated or “fresh” HEU and has the most stringent set of recommended physical protection measures. Lower quantities of special nuclear material are referred to as Category II and Category III quantities. In addition, IAEA aims to detect and deter the diversion of nuclear material for nonpeaceful purposes through its safeguards program. Under this program, IAEA inspects facilities and locations containing nuclear material, as declared by each country, to verify peaceful use, among other things. IAEA maintains information on holdings of worldwide nuclear materials for 179 countries but, according to IAEA officials, it does not share this information with other countries. IAEA also receives some information regarding the amount and kinds of nuclear material at all sites through its safeguards activities and International Physical Protection Advisory Service missions. These missions are conducted at the request of the host country and enable IAEA to assist countries in strengthening their national nuclear security regimes; however, this information is not shared with other countries. According to GTRI officials, the IAEA also supports DOE efforts to remove vulnerable nuclear material from and convert research reactors in other countries. U.S. nuclear cooperation agreements: U.S. nuclear cooperation agreements and U.S. interagency physical protection visits provide another mechanism to ensure that U.S.-origin nuclear material overseas at partner sites is not vulnerable. As of October 2014, the United States had 21 nuclear cooperation agreements in force for peaceful civilian nuclear cooperation with partners including foreign countries, the European Atomic Energy Community (EURATOM), IAEA, and Taiwan. The Atomic Energy Act of 1954, as amended, requires all U.S. nuclear cooperation agreements to contain guarantees that cooperating parties will maintain adequate physical security for transferred nuclear material and any special nuclear material used in or produced through the use of any material, or production or utilization facilities transferred pursuant to the agreement. However, as we found in our September 2011 report, U.S. agencies’ ability to monitor and evaluate whether nuclear material subject to U.S. nuclear cooperation agreement terms is physically secure and accordingly not vulnerable is contingent on partners granting access to facilities where nuclear material is stored. As we further reported, U.S. interagency physical protection teams have conducted physical protection visits to monitor and evaluate the physical security of U.S. nuclear material at facilities overseas when permitted. U.S.-Russian agreements: A series of agreements between Russia and the United States has established a mechanism to facilitate U.S. participation in efforts to ensure the security of nuclear materials in Russia—a country estimated to hold at least 617,000 kilograms of HEU and 120,000 kilograms of plutonium. In 1991, Congress authorized DOD to establish the Nunn-Lugar Cooperative Threat Reduction program to provide nuclear security assistance to Russia and the former Soviet states. In June 2013, the Cooperative Threat Reduction umbrella agreement—which established an overall legal framework for providing such assistance—expired, and joint nuclear security activities in Russia since have been conducted under a 2003 Framework Agreement on a Multilateral Nuclear Environmental Programme in the Russian Federation (MNEPR). According to GTRI officials, GTRI’s activities to return Russian- origin HEU and plutonium to Russia and convert reactors in Russia is covered by a May 2004 U.S.-Russia government-to-government agreement. U.S. fuel and nuclear material return program: Along with its work with Russia to help secure and protect former Soviet nuclear material, the United States has also actively sought to return U.S.-origin and, in some cases, nuclear material of other origins to the United States. In general, unirradiated HEU is returned to the Y-12 National Security Complex near Oak Ridge, Tennessee; spent HEU is returned to either Idaho National Laboratory in Idaho Falls, Idaho, or the Savannah River Site in South Carolina; and separated plutonium is returned to the Savannah River Site. Because the process of returning the nuclear materials to the United States could potentially affect the environment, these returns are analyzed under the National Environmental Policy Act (NEPA). DOE regulations for implementing NEPA dictate that these reviews should start “as soon as possible” after DOE proposes an action. Since 1996, DOE has completed several NEPA reviews related to the return of nuclear materials. In accordance with department policy, DOE pays for returns of material from non-high income countries but charges high income countries a fee. DOE achieved its goals for the initiative for the key activities of removing or disposing of HEU and plutonium and downblending HEU; however, it did not achieve its goals for upgrading the physical protection of HEU and plutonium at vulnerable sites or for converting reactors and associated facilities that use HEU to LEU. We used DOE’s fiscal year 2010 budget request to identify the goals that DOE had established at the initiative’s start for the four key activities. DOE reported that it had spent more than $650 million on its efforts during the initiative. Table 1 below summarizes DOE’s progress toward its goals for the four key activities and the amount spent for each. DOE’s GTRI and MPC&A exceeded their goals for the following key activities during the initiative: Removing or disposing of HEU and plutonium: DOE’s GTRI exceeded its goal for removing and disposing of HEU and plutonium. According to GTRI records, over the course of the initiative (April 2009 through December 2013), GTRI removed 1,581 kilograms of HEU and plutonium, exceeding its goal of 1,201 kilograms as reported in DOE’s fiscal year 2010 budget request. GTRI removed all HEU from 11 countries and Taiwan under the initiative, bringing the number of countries where all HEU has been removed to a total of 26 plus Taiwan. According to GTRI officials, these efforts involved close international cooperation with officials in the country from where the nuclear material was removed. Appendix IV provides additional details of all HEU and plutonium removed during the initiative, including the originating country, site, amount and type of nuclear material, and the month and year the material was removed. In addition, GTRI officials told us they disposed of additional materials by assisting in the downblending of 1.5 kilograms of HEU in Argentina in June 2013 and 33 kilograms of HEU in Kazakhstan in October 2011. According to GTRI records, it spent approximately $531 million on these removal and disposition efforts. In addition, GTRI in 2013 reported that it had disposed of other HEU by verifying the downblending of 1,240 kilograms of HEU in the United Kingdom and 112 kilograms of HEU in Japan. However, we did not include these as achievements toward its goal of removing or disposing of material because, according to GTRI officials, the downblending of HEU in the United Kingdom occurred many years prior to the initiative, GTRI was not able to determine that the downblending of material in Japan occurred during the initiative and, in both cases, it is unclear to what extent GTRI played an active role in identifying a disposition pathway for these materials. Downblending HEU: DOE’s MPC&A exceeded its goal for downblending 2,700 kilograms of HEU. According to MPC&A officials, MPC&A verified the downblending of 4,900 kilograms of HEU to LEU in Russia during the initiative. MPC&A officials estimated they spent more than $70 million on these efforts. DOE did not achieve its goals for the following key activities during the initiative: Upgrading physical protection: DOE did not achieve its goals for upgrading the physical protection of HEU and plutonium at 43 buildings. Specifically, according to MPC&A documents, MPC&A upgraded the physical protection for HEU and plutonium at 32 buildings. According to these officials, the upgrades of the 32 buildings were completed at three sites in Russia. MPC&A officials estimated they spent about $33 million on these efforts. In addition, although it did not set a goal for this activity, according to GTRI officials, it completed physical protection upgrades at Mexico’s Salazar site and continued work at South Africa’s Pelindaba site during the initiative. The work at Pelindaba was completed in January 2015. GTRI reported it spent approximately $16 million for these efforts. Converting reactors: GTRI did not achieve its goal to convert 34 foreign reactors from HEU to LEU during the initiative. Specifically, GTRI converted 23 foreign reactors, 11 fewer than its goal for conversions by the end of fiscal year 2013. GTRI reported it spent approximately $5 million on these efforts. Appendix V provides more details on reactor conversions during the initiative, including country, site, and date the conversion was completed or the reactor was verified as shut down. GTRI officials told us in July 2014 that political and technical challenges have complicated efforts to convert research reactors and isotope facilities. For instance, according to these officials, delays in the development of LEU replacement fuel to power the European Union high- performance reactors and the development of LEU targets for medical isotope production processes have posed challenges in meeting goals but, according to GTRI officials, work continues to ensure that the objectives will be met as soon as possible. DOD and other agencies also made contributions toward the initiative. For example, DOD officials reported that DOD contributed to the removal of nuclear material by (1) aiding in shipments of Russian warheads from deployed sites to more central repositories or to facilities for dismantlement and (2) providing physical protection upgrades and security efforts at sites during the initiative. DOD officials reported the agency spent $178 million and $78 million, respectively, in these areas, bringing the U.S. agency total initiative-related spending in the four key activities to about $912 million. Moreover, as appendix III further details, DOE, DOD, and other U.S. agency officials responding to our data collection instrument indicated that about half of initiative-related spending was for efforts other than the four key activities supporting site lockdown programs to remove or secure vulnerable nuclear materials discussed in this report. DOE, DOD, and other U.S. agencies reported to us that their agencies spent more than $1 billion on such activities. These activities included, for example, training on physical protection, protective force, and transportation security; material control and accounting training; and constructing nuclear centers of excellence worldwide. DOE has developed new goals since the end of the initiative for continued efforts related to the initiative’s four key activities to help secure or remove HEU and plutonium. However, four challenges may hamper future progress: (1) access to some countries and sites may continue to be a challenge, (2) DOE and other U.S. agencies have not completed an inventory of U.S.-obligated plutonium overseas, (3) DOE has not prioritized its inventory list of HEU at foreign locations for removal or disposition, and (4) DOE and other agencies have not visited key sites in more than 20 years to determine whether U.S.-origin material on-site is adequately protected. DOE has developed goals for all four key activities that are expected to result in securing or removing HEU and plutonium going forward since the initiative concluded in 2013. DOE included three of these goals in its fiscal year 2015 budget request. GTRI provided us with information regarding its goal for removing or disposing of HEU or plutonium. Table 2 shows DOE’s goals for these activities, as well as its planned spending to achieve these goals. More specifically, DOE has developed the following goals since the initiative ended in 2013: Removing or disposing of HEU and plutonium: According to DOE planning documents and information that department officials provided to us, GTRI’s goal is to remove or dispose of an additional 1,029 kilograms of fresh and spent HEU, as well as plutonium worldwide from 2014 to December 2019. GTRI also specified that this 1,029 kilograms of HEU includes 2 kilograms of spent HEU to be downblended in Argentina and 3 kilograms of spent HEU to be downblended in Indonesia, which would result in the elimination of HEU in both of those countries. In 2014, GTRI removed 134 kilograms of HEU and plutonium. In fall 2014, GTRI gave us a list of nuclear materials it would like to address, either by removal or disposition. This list, which includes 2,259 kilograms of materials, far exceeds GTRI’s 1,029 kilograms goal, but GTRI officials told us they believe 1,029 is a reasonable target for nuclear material removals during this period. Downblending HEU: According to MPC&A’s fiscal year 2015 budget request, MPC&A’s goal was to support the downblending of 5,200 kilograms of HEU in Russia through fiscal year 2019. However, Russian officials decided in December 2014 to reduce DOE’s scope of work in Russia and, at that time, announced that the downblending program would be discontinued. Upgrading physical protection: According to MPC&A’s fiscal year 2015 budget request, MPC&A had a goal of supporting physical protection upgrades at 11 buildings in Russia and completing those upgrades by the second quarter of fiscal year 2015. As of December 2014, MPC&A completed upgrades at 3 of these buildings. However, MPC&A officials told us that, because of Russian officials’ decision in December 2014 to reduce DOE’s scope of work in Russia, activities to support physical protection upgrades at the remaining 8 buildings at the site are to be completed by the Russians using Russian funds. Russian officials made no assurances as to the scope of work in completing these upgrades or adherence to DOE’s original timelines. Converting reactors: DOE’s fiscal year 2015 budget request states that GTRI’s goal is to convert 27 foreign research reactors and medical isotope production facilities to LEU by the end of fiscal year 2019. GTRI officials told us in July 2014 that approximately 100 foreign civilian research reactors and isotope production facilities worldwide currently use HEU, with about two-thirds of those remaining reactors in Russia. GTRI officials gave us a list of 13 foreign reactors or medical isotope production facilities they plan to either convert or verify the shutdown of from 2014 through 2016. In addition to DOE’s goals for the four key activities associated with removing and securing HEU and plutonium since the initiative ended in 2013, other agencies have some plans going forward. Collectively, DOD, NRC, and State officials told us that they plan to spend $27 million from 2014 through 2019 for initiative-related activities. For example, DOD officials cited no specific future goals but told us its Cooperative Threat Reduction program plans to spend $4 million to complete nuclear material removals at certain Russian sites by dismantling nuclear submarines and consolidating the nuclear material at secure sites elsewhere in Russia. Officials from agencies participating in the initiative also stated that, in the future, the majority of expected spending is to be for efforts other than for the four key activities. Specifically, officials from DOE and other agencies told us that they plan to spend almost half, or about $600 million of an estimated $1.3 billion in planned spending from 2014 through 2019 for efforts other than the four key activities, such as, for example, training activities. For example, DOD officials told us that DOD’s Cooperative Threat Reduction program plans to spend $34 million to assist in developing nuclear security centers of excellence, which are centralized locations where countries or regions can send professionals for training in various aspects of nuclear security, such as physical protection best practices and emergency preparedness and response. We identified four challenges that may hamper DOE and other agencies’ abilities to meet their goals and maintain progress to secure HEU and plutonium going forward: (1) access to some countries and sites may continue to be a challenge, (2) DOE and other U.S. agencies have not completed an inventory of U.S.-obligated plutonium overseas, (3) DOE has not prioritized its inventory list of HEU at foreign locations for removal or disposition, and (4) DOE and other agencies have not visited key sites in more than 20 years to determine whether U.S.-origin material on-site is adequately protected. The first challenge we identified that may hamper future progress is that U.S. agencies may continue to encounter resistance by major allied and other countries to allowing access to some sites and agreeing to remove or secure vulnerable nuclear materials. Some countries have declined to grant U.S. officials access to sites or have denied permission to return vulnerable nuclear materials during the initiative. DOE and other U.S. agency officials told us that they continue to work with countries to secure additional vulnerable materials. Further details are classified and thus were omitted from this version of the report. The second challenge that may hamper future progress is that U.S. agencies may not have complete information about the locations of U.S.- obligated plutonium worldwide. In September 2011, we concluded that without an accurate inventory of U.S. nuclear materials—in particular, weapons-usable HEU and separated plutonium—the United States does not have sufficient assurances regarding the location of materials for accounting and control purposes. As a result, we recommended that State, working with DOE and NRC, determine a baseline inventory of U.S.-obligated HEU and separated plutonium for those partners with which the United States has transferred material but does not have annual inventory reconciliation, and establish a process for conducting annual reconciliations of inventories of nuclear material on a facility-by- facility basis. DOE, NRC, and State did not agree with this recommendation, but they have taken actions to partially implement it. Specifically, DOE completed an initial inventory of U.S.-origin HEU overseas, as published in a June 2013 GTRI report. GTRI has stated that “particularly troubling” is the high volume and rapid expansion of worldwide civilian plutonium inventories, which have grown by an additional 100,000 kilograms in the past 15 years to approximately 310,000 kilograms worldwide. U.S. agencies have not, however, completed an inventory of all U.S.-obligated separated plutonium stocks worldwide to determine the amount and locations of potentially vulnerable plutonium that could be addressed in future DOE efforts. A May 2013 GTRI document noted it planned to account for all civilian plutonium inventories by the end of 2016. We continue to believe that an inventory of all U.S.-obligated plutonium overseas is necessary to both identify nuclear material and to account for and ensure that such material is protected in accordance with international physical security guidelines. The third challenge that may hamper future progress is that DOE has not prioritized for return or disposition nuclear material stocks, including newly identified U.S.-origin HEU overseas from its recent accounting of U.S.- origin HEU overseas. As noted above, DOE completed an initial inventory of U.S.-origin HEU overseas in June 2013; however, to date, DOE has not prioritized this list to identify the most vulnerable U.S.-origin HEU overseas to prioritize for return or disposition. According to GTRI’s June 2013 report summarizing initial inventory information regarding U.S.-origin HEU at foreign locations, more than 13,000 kilograms of U.S.-origin HEU remain worldwide, including 3,526 kilograms of unirradiated or fresh U.S.- origin HEU and 1,771 kilograms of irradiated U.S.-origin HEU eligible for return. GTRI officials have stated that its effort at accounting for U.S.- origin HEU overseas identified significant quantities of nuclear material that could be addressed going forward; its June 2013 report stated that it would begin prioritizing the removal or disposition of the most attractive nuclear material the study identified. However, as of March 2015, GTRI has not identified which stocks it believes are the most attractive and contain the most vulnerable materials and, therefore, should be priorities for return or disposition. In March 2015, GTRI officials told us that GTRI’s priorities for U.S.-origin material, from highest to lowest priority, consist of (1) removing or confirming the disposition of as much excess fresh HEU as possible; (2) returning or confirming the disposition of U.S.- origin irradiated HEU that is eligible for return; and (3) working with international partners to develop disposition pathways for additional irradiated material that could be attractive to terrorists for a nuclear weapon. However, as of May 2015, GTRI had neither provided GAO with a detailed or specific prioritized list of nuclear materials for return as noted in July 2014 and reaffirmed in January 2015, nor provided a time frame for doing so. DOE’s order on internal control calls for “processes for planning, organizing, directing, and controlling operations designed to reasonably assure that programs achieve intended results, and decisions are based on reliable data,” and notably the initiative called for all vulnerable nuclear material to be secured, with a strategy to identify and prioritize the most vulnerable sites. In addition, Congress continues to express interest in securing the most vulnerable nuclear materials. Specifically, a committee of Congress in June 2013 requested that DOE, among other things, develop a new strategic plan to secure and dispose of nuclear materials that pose the greatest terrorism risk to the United States. Without an updated list of nuclear materials that prioritizes for returns or disposition, DOE and other U.S. agencies do not have reasonable assurance that they are prioritizing resources to identify, include, and address the most highly vulnerable and attractive nuclear materials that remain outside of the United States, and, where feasible, identify a final disposition pathway in the United States or elsewhere. The fourth challenge that may hamper future progress is that DOE and other agencies have not visited key sites to ascertain whether U.S.-origin nuclear material is protected in accordance with international physical security guidelines. This is consistent with the findings in our September 2011 report, which noted that U.S. interagency physical protection teams had not visited all partner facilities believed to contain Category I quantities of U.S.-origin nuclear material at least once every 5 years—an official interagency goal. As a result, we recommended in September 2011 that State work with other agencies to facilitate visits to sites that had not been visited and that are believed to hold Category I nuclear material. State did not agree with this recommendation, but it has taken actions to implement it. In addition, in our September 2011 report, we found that U.S. agencies did not have a formal process for coordinating and prioritizing physical protection visits, and we recommended that DOE work with U.S. agencies to develop formal goals for and a process to determine which foreign facilities to visit in the future, and we noted the goals should be formalized and agreed to by all agencies. We additionally recommended that DOE work with other agencies to review performance information to determine which countries containing Category I U.S. nuclear material have been visited in the last 5 years and determine whether facilities not meeting international physical security guidelines were revisited in a timely manner. DOE did not agree with these recommendations either, but it has taken actions to implement them. In recent years, DOE has worked with U.S. agencies to develop a formal methodology to prioritize physical protection visits, as detailed in a September 2012 document. These efforts notwithstanding, information regarding the security status of some sites storing U.S. nuclear materials remains unknown. Records of recent U.S. physical protection visits show that U.S. teams have not visited many sites believed to be storing Category I or Category II quantities of U.S.-origin HEU in more than 20 years to ascertain whether material there is being protected in accordance with international physical security guidelines. More specifically, we identified four Category I and seven Category II sites holding U.S.-origin HEU that U.S. interagency physical protection teams have not visited in at least 20 years. Collectively, these sites hold 2,261 kilograms unirradiated U.S.-origin HEU and 1,327 kilograms of irradiated U.S.-origin HEU. An NRC official told us in March 2015 that any U.S. material exported to a partner country would be expected to be maintained in accordance with the international physical security guidelines NRC references in its regulations, and that NRC’s regulations provide for the “continuing review” of previously exported material. In addition, in March 2012, the DOE Deputy Administrator for Defense Nuclear Nonproliferation testified that DOE led U.S. interagency teams on visits to ensure that partner sites meet revision 5 of international physical security guidelines. Without an assessment of the physical security conditions of the U.S-origin nuclear material at these Category I and Category II facilities, DOE and U.S. agencies are not able to determine if this material is protected in accordance with international security guidelines. In addition, without information on this material, DOE and U.S. agencies lack reasonable assurance that they are removing or disposing of the most vulnerable nuclear materials, in accordance with the stated goals of the president’s initiative and the expressed interest of a committee of Congress. In addition to the challenges we identified above, as we reported in our August 2015 classified report, vulnerabilities remain worldwide after the conclusion of the initiative in December 2013. For example, our review of GTRI records indicates that about one-third of the nuclear material stocks prioritized for removal in 2010 have not been removed. We reviewed GTRI’s August 2010 list of prioritized stocks for nuclear material removals and compared them with information regarding the nuclear materials returned by GTRI through January 2015. Of the 29 specific stocks of nuclear material deemed “1A” priorities for removal in August 2010, GTRI has removed 18 as of January 2015, yet more than 1,000 kilograms of nuclear materials remain at sites that were priorities for removal and haven’t been removed. In addition, records of recent years’ U.S. physical protection visits continue to show that some foreign sites are not protected in accordance with the current international physical security guidelines. Our analysis of DOE documentation shows U.S. interagency physical protection teams made 53 assessments from April 2009 through March 2015 to observe and evaluate the physical protection afforded U.S.-origin nuclear material of 43 sites. Of these 43 sites, 32 sites— including 17 Category I sites, 10 Category II sites, and 5 Category III sites—were found to meet international security guidelines when they were assessed at the time of the initial visit. This represents improvement since our September 2011 report; however, 6 Category I sites, 6 Category II sites, and 1 Category III site were found to not meet international physical security guidelines at the time of the initial visit. Additional details about this and other information regarding vulnerabilities that remain at the end of the initiative are classified and were omitted from this version of the report. DOE has made progress under the President’s 2009 initiative to remove HEU and plutonium from vulnerable sites, verify the downblending of HEU to LEU, physically protect vulnerable sites, and convert reactors and production facilities from HEU to LEU. Physical security is a sovereign nation responsibility and activity, and thus it is important that U.S. agencies coordinate and cooperate with these nations to gain access to overseas sites containing U.S.-origin nuclear material. However, while progress has been made, significant quantities of potentially vulnerable nuclear materials remain, and DOE and other U.S. agencies may have opportunities to improve their ability to ensure that as much of this nuclear material as possible can be secured. We commend GTRI for taking the initiative to complete an initial inventory of U.S.-origin HEU overseas as we recommended in September 2011. However, GTRI’s effort was limited to U.S.-origin HEU exported overseas; it does not account for U.S.-obligated plutonium overseas, as we recommended in the same report. An inventory of all U.S.-obligated plutonium overseas is important to both identify nuclear material and to account for and ensure that such material is protected in accordance with international physical security guidelines. Moreover, because DOE and U.S. agencies have not completed an inventory of all U.S.-obligated plutonium inventories overseas to determine the amount and locations of potentially vulnerable plutonium that could be addressed in future DOE efforts, it is possible that additional quantities of U.S.-obligated plutonium are vulnerable. As we recommended in September 2011, we continue to believe that U.S. agencies should complete an inventory of all U.S.- obligated plutonium overseas to determine whether these nuclear materials are vulnerable, as well as to determine the amounts and locations of additional quantities of U.S.-obligated plutonium at worldwide sites that could be addressed in future DOE efforts. DOE’s GTRI has stated general priorities for returns and dispositions of HEU at foreign locations. In July 2014, GTRI officials stated they were undertaking an effort to prioritize information regarding inventories of HEU, to include U.S.-origin HEU identified in its June 2013 inventory reconciliation. However, as of May 2015, GTRI had not provided a detailed or specific prioritized list of nuclear materials, including recently identified U.S.-origin HEU at foreign locations, for return or disposition, to ensure that the most vulnerable nuclear materials are returned or provided a time frame for doing so. DOE’s order on internal control calls for processes for planning, organizing, directing, and controlling operations to ensure that programs achieve intended results, and decisions are based on reliable data, and the initiative called for all vulnerable nuclear material to be secured, with a strategy to identify and prioritize the most vulnerable sites. Without an updated list of nuclear materials that prioritizes inventories for removal or disposition, DOE and other U.S. agencies do not have reasonable assurance that they are prioritizing resources to identify, include, and to address the most highly vulnerable and attractive nuclear materials that remain outside of the United States, and, where feasible, identify a final disposition pathway in the United States or elsewhere. DOE has taken steps to develop a methodology to select and prioritize physical protection visits, as we had recommended in our September 2011 report. However, similar to our findings in our 2011 report, we found U.S. agency physical protection teams have not visited some Category I and Category II U.S.-origin nuclear material in at least 20 years to determine whether it is protected in accordance with international physical security guidelines. We do not dispute DOE’s September 2012 methodology to prioritize physical protection visits. Notwithstanding the new methodology for prioritizing visits, until U.S. physical security teams visit Category I and Category II sites that have not been visited in many years, it will be difficult to know whether such materials are being adequately protected in accordance with current international physical security guidelines. We recognize that limited access to key major allied and other countries’ sites has hampered U.S. agency efforts to secure all vulnerable nuclear materials worldwide. However, without information on the physical security of these sites, DOE will not have reasonable assurance that DOE or other U.S. agencies are removing or disposing of the most vulnerable nuclear materials, in accordance with the stated aims of the President’s initiative and the expressed interest of a committee of Congress. We are making two recommendations to ensure that the global initiative to remove and secure vulnerable nuclear materials achieves its stated goals of securing the most vulnerable nuclear materials and ensure that U.S. agencies are able to secure as much vulnerable nuclear material as possible: To ensure that the most vulnerable nuclear materials are given priority for removal or disposition, we recommend that the Secretary of Energy complete the prioritization for removal or disposition of inventories of identified nuclear materials at foreign locations, including recently identified stocks of U.S.-origin HEU at foreign locations, to determine priorities for efforts going forward. To ensure that Category I and Category II U.S.-origin nuclear material is protected in accordance with international physical security guidelines, we recommend that the Secretary of Energy work with U.S. agencies by requesting and, where feasible, undertaking physical protection visits at partner country sites that hold Category I and Category II quantities of U.S.-obligated nuclear material that have not been visited in more than 5 years—particularly those that have not been visited in 20 or more years. We provided a draft of this report to the Departments of Energy, Defense, and State and the Nuclear Regulatory Commission for their review and comment. DOE provided written comments, as reproduced in appendix VI. NRC provided a technical comment on the report, which we incorporated. DOD and State did not comment on our report. In its comments, DOE agreed with our recommendations and provided information on specific actions taken and planned to address each recommendation, as well as timelines for their completion. Regarding our first recommendation that DOE complete its prioritization of nuclear material at foreign locations to identify the most vulnerable materials and ensure they are given priority for removal and disposition efforts, DOE stated that it was building on information provided in its 2014 report to Congress and would complete its revised prioritization list by September 30, 2015. Our second recommendation is that DOE request and, where feasible, undertake physical protection visits at partner country sites that hold Category I and Category II quantities of U.S.-obligated nuclear material that have not been visited in more than 5 years—particularly those that have not been visited in 20 or more years. DOE stated that it agrees with the recommendation but considers it closed, as it has continued to schedule and prioritize visits in an effort to achieve the goal of visiting all Category I sites every 5 years. However, we disagree with DOE’s assessment that the department has taken action to close this recommendation. As our report notes, we identified four Category I and seven Category II sites that have not been visited in at least 20 years. DOE’s comments note that, in some cases, visits have not been possible because access has been delayed or denied due to difficult political circumstances. However, as we note in the report, it is not clear that DOE has sought visits to all Category I and Category II sites that have not been visited in at least 20 years. In addition, DOE has not further identified which sites on this list or other Category I or Category II sites containing U.S. nuclear material that have not been visited in at least 5 years that it considers not feasible to visit due to political challenges. We continue to believe that our recommendation should be implemented to ensure that Category I and Category II U.S.-origin nuclear material is protected in accordance with international physical security guidelines. In its letter DOE also stated that our evaluation provides a limited view of the physical protection activities involved in the initiative to secure all vulnerable nuclear materials around the world in 4 years, and that our characterization of “Other” to capture financial data for all other MPC&A activities could be misleading as the category of “Other” encompasses a broad scope of technical efforts that are nonetheless critical components of the nonproliferation mission. We disagree that our evaluation provides a limited view of activities under the initiative to secure vulnerable nuclear materials. As our report notes, the initiative’s focus is on programs to secure vulnerable nuclear materials, specifically site lockdown programs. We further note that our report focuses on four key activities to secure or remove HEU or plutonium: (1) removing or disposing of HEU and plutonium to secure locations in the United States or elsewhere; (2) downblending HEU to LEU; (3) upgrading the physical protection of HEU and plutonium at vulnerable sites; and (4) converting nuclear reactors and associated facilities that use HEU to LEU. Our report provided additional information regarding agency-reported spending for activities that were not among these four key activities as “other” spending. DOE cites other activities such as sustainability and training as being critical components of the nonproliferation mission. We do not disagree. However, as our report notes, in accordance with the initiative’s stated focus of site lockdown programs to protect vulnerable nuclear materials, activities such as MPC&A sustainability activities—such as support for the maintenance, repair, and logistical services and spare equipment for the improved security systems—is beyond the scope of the initiative’s stated focus of site lockdown programs as well as this report. We are sending copies of this report to the appropriate congressional committees; the Secretaries of Defense, Energy, and State; the Chairman of the NRC; and other interested parties. In addition, the report is available at no charge on the GAO website at http://www.gao.gov. If you or your staff members have any questions about this report or need additional information, please contact me at (202) 512-3841 or trimbled@gao.gov. Contact points for our Offices of Congressional Relations and Public Affairs may be found on the last page of this report. Key contributors are listed in appendix VII. This report: (1) assesses the extent to which the Department of Energy (DOE) achieved its goals associated with the 2009 initiative’s four key activities of removing, downblending, and upgrading the physical protection of highly enriched uranium (HEU) and plutonium, and converting facilities that use HEU, and (2) examines DOE’s goals since the end of the initiative associated with the four key activities and identifies and assesses challenges, if any, that may limit DOE’s ability to secure as much vulnerable nuclear material as possible. To conduct this work, we reviewed relevant documents and interviewed federal officials responsible for implementing the initiative. In particular, to assess the extent to which DOE achieved its goals associated with the initiative’s four key activities, we reviewed the National Security Council’s (NSC) interagency strategy and the document it circulated to agencies in 2011 to identify the primary objectives of the initiative and how DOE and participating federal agencies were expected to contribute in meeting these objectives. We also reviewed DOE’s 2009 classified plan and fiscal year 2010 budget request—released in May 2009—to identify the goals that DOE had established at the initiative’s start for contributing to the initiative’s four key activities. Because the key activities associated with removing and securing HEU and plutonium are primarily undertaken by DOE, we focused on DOE’s contributions but also included information regarding the contributions of other federal agencies involved in the initiative, as appropriate. In particular, we relied on DOE’s performance metrics and goals for removing, downblending, and physically protecting nuclear materials, and converting reactors and production facilities from HEU to low-enriched uranium (LEU) as presented in its fiscal year 2010 budget request to assess progress toward achieving goals. We used DOE’s fiscal year 2010 budget request to identify the goals that DOE had established at the initiative’s start for contributing to the four key activities because it was issued in May 2009, 1 month after the start of the initiative and, in the absence of other annually published forward-looking information since the initiative’s start, we identified it as a reasonable indicator of DOE’s expectations and goals to be accomplished in the initiative. We interviewed officials from DOE, the Department of Defense (DOD), the Nuclear Regulatory Commission (NRC), and the Department of State (State) and discussed these issues with NSC officials to determine the extent to which these agencies contributed to the initiative and their plans going forward. Through these interviews, we identified challenges these agencies confronted during the initiative and the challenges that may lie ahead. We also sent a data collection instrument to relevant offices in DOE, DOD, NRC, and State to obtain additional information on each agency’s contribution to the initiative, how much each agency spent on these efforts, and how they plan to contribute to them. We received responses from each of the agencies and offices that we sent the data collection instrument to, namely, DOE’s Global Threat Reduction Initiative (GTRI), DOE’s Material Protection, Control and Accounting (MPC&A) program, DOD’s Cooperative Threat Reduction program, State, and NRC. We analyzed the completed responses to determine how much agencies spent from May 2009 through December 2013 and to collect agency estimates of spending for fiscal years 2014 through 2019. We followed up with agency officials for clarification on questions related to the data as necessary. While the data collected generally tracked spending by fiscal year, they do not track completely with the time frame of the initiative, which ran from April 2009 through December 2013. To address this, we divided the fiscal year 2009 budget figures in half to account for the 6 months in calendar year 2009 that were a part of the initiative (from April 2009 through September 2009). We did this for all agencies except GTRI, which provided us with figures pulled from its G2 Financial Management System that officials said were specific to the months and years of the initiative. In addition, we accounted for the 3 months of fiscal year 2014 that were a part of the initiative (i.e., October 2013 through December 2013) by dividing the fiscal year 2014 spending figures by 4 and including one-fourth of those figures in each agency’s totals for initiative spending, with the exception of GTRI. Although this effort is intended to better capture the amount of spending during the specific time frames of the initiative, it is unclear whether the spending was distributed equally among the months of the fiscal years. Therefore, the numbers that we are using are estimates. We adjusted the data for inflation, and all data are in 2014 dollars unless otherwise noted. To assess the reliability of the spending data, we manually tested it for missing values, obvious errors, or outliers. We then compared the data with related budget information available in the agencies’ budget requests. We also included questions in our data collection instrument and received responses regarding how agencies compiled the data and maintained their data quality and data systems, and we interviewed knowledgeable agency officials to discuss the data. Through these efforts, we determined the data were sufficiently reliable for the purposes of this report. We undertook additional efforts to specifically assess each of the four key activities as follows: For removing or disposing of HEU or plutonium, we reviewed records from GTRI of nuclear materials returned, plans for future repatriation of remaining nuclear materials, the estimated amounts of remaining nuclear materials, and future priorities. We focused specifically on GTRI records because GTRI is the program chiefly responsible for such activity. We compared these efforts with goals achieved during the initiative to determine the amounts already removed and disposed of, and we interviewed GTRI officials to discuss these activities, as well as plans and goals for removals going forward. To determine the goals GTRI had for removals and dispositions, we reviewed the goals for removals and dispositions from its fiscal year 2010 budget request and subtracted the fiscal year 2013 goal for removal from the amount of nuclear material GTRI reported it had removed in fiscal year 2009 according to its fiscal year 2011 budget request. We subtracted the amount that GTRI reported it had removed between April 2009 and September 2009 to avoid double counting that figure. We also included removals that GTRI made in the 3 months beyond the end of fiscal year 2013 to try to better capture activities during the initiative itself, which ended in December 2013. For downblending, we reviewed DOE documentation of activities in support of downblending HEU and interviewed DOE’s MPC&A officials about these efforts. To determine the amount of HEU planned for downblending during the initiative, we used the fiscal year 2010 budget request numbers. We subtracted 12,600 kilograms (the amount for fiscal year 2010 that began on October 1, 2009) from 15,300 kilograms (the amount targeted for fiscal year 2013, which concluded on September 30, 2013) to arrive at 2,700 kilograms as an estimate for amount planned for downblending during the initiative. For physical protection, we reviewed DOE information regarding buildings containing HEU or plutonium secured during the initiative, as well as information regarding plans going forward, including DOE information regarding the number of buildings secured at the start of the initiative and DOE’s fiscal year 2010 budget request. We compared the records with goals achieved during the initiative and interviewed DOE officials to discuss these activities, as well as plans and goals going forward. With regard to spending on this activity, MPC&A provided us with updates to the spending data they originally gave us in order to better accommodate the initiative’s activities as we describe them. Specifically, in the updated data, officials reallocated spending that they had originally categorized as supporting physical protection into the “other” category, which includes spending on efforts that are not among the four key activities of the initiative. According to MPC&A officials, the reallocated figures actually covered activities related to material control and accounting, which is not included in the four key activities. For conversion of reactors from HEU to LEU, we reviewed lists of planned and completed reactor conversions from GTRI, as GTRI is the lead program for this activity. We compared the lists with goals achieved during the initiative and interviewed GTRI officials to discuss these activities, as well as any plans and goals for reactor conversions going forward. To determine the goal for foreign reactor conversions during the initiative, we reviewed the fiscal year 2010 budget request and subtracted the target for foreign reactor conversions for fiscal year 2013 from the number of conversions completed in fiscal year 2008. We excluded foreign reactors that had already been converted at the time that the initiative started, as well as two U.S. reactors converted during the time of the initiative, on which GTRI officials reported they spent $17 million before inflation (or $18 million in 2014 constant dollars). Without these adjustments, the goal using the fiscal year 2010 budget request as a basis would be 34 reactors converted. We then reviewed other DOE documents to ensure that we addressed foreign conversions that were completed between the start of fiscal year 2009 in October 2008 and the start of the initiative in April 2009. We then reviewed DOE priority lists to determine the number of U.S. reactors that were converted and those that awaited conversion, in order to ensure that we did not include those in the goal for the number of foreign reactors converted during the initiative. We did not focus on consolidation activities in this report, although such activities would be included in the stated focus of the NSC’s initiative— site lockdown programs to secure and remove HEU and plutonium—and NSC officials indicated in July 2014 that consolidation was a core effort of the initiative. We are not assessing consolidation activities under the initiative because DOE neither set goals for consolidation activities, nor did it include any in its budget requests. To examine DOE’s goals associated with the four key activities since the end of the initiative, and to assess any challenges that may limit DOE’s ability to secure as much vulnerable nuclear material as possible, we collected and analyzed other information where available. Specifically, to identify goals going forward after the initiative concluded in December 2013, we reviewed the DOE’s performance metrics and goals as presented in its fiscal year 2015 budget request issued in March 2014, as well as other information supplied by DOE. We identified and analyzed DOE and other U.S. agency information regarding its programs for ensuring that U.S.-nuclear materials are physically protected consistent with international security guidelines at foreign locations, and we reviewed DOE information regarding planned nuclear material removals and dispositions to identify and assess any challenges that may limit DOE’s ability to secure as much vulnerable nuclear material as possible. To provide information about any vulnerabilities that may pose challenges that remained at the end of the initiative, we analyzed U.S. government data sources. For example, we compared DOE’s August 2010 list of HEU and plutonium for which DOE set a priority for removal or disposition under the initiative to DOE records of HEU and plutonium removals and dispositions to determine how much of the prioritized nuclear material remained in vulnerable locations to be addressed going forward. We also reviewed records of U.S. physical protection visits to determine whether sites with U.S.-origin HEU were following international physical protection guidelines to secure the material. We reviewed previous GAO reports to identify and assess U.S. agency progress in implementing recommendations aiming to improve agency planning and oversight of vulnerable nuclear materials. We reviewed inventory information regarding U.S.-origin HEU overseas, in particular GTRI’s June 2013 report, Reconciliation of U.S.-Origin Highly Enriched Uranium Exported to Foreign Countries for Civilian Use, and we reviewed other information, as available, to determine disposition plans for these nuclear materials. We reviewed current U.S. agency criteria for the removals of various types of nuclear materials and returns of such materials to the United States, and we compared them with DOE records to identify instances in which proposed returns of nuclear materials exceed or differ from planned for types or quantities. We interviewed officials from DOE, DOD, NRC, and State to learn more about how they plan to contribute to the key activities going forward, as well as challenges that may lie ahead. We visited DOE’s Savannah River Site to meet with officials responsible for nuclear material returns made under the initiative. We also visited key sites in three countries that hold or held U.S.-origin HEU and conducted interviews with foreign country representatives to identify any concerns regarding DOE and U.S. agencies’ ability to return the most vulnerable nuclear materials in accordance with initiative aims. We prepared and distributed a standard set of questions to foreign government officials from countries we did not visit; however, we did not use information obtained through these question sets as our response rate was low. Specifically, of the 14 countries that received the survey, 5 responded to the questions. We conducted this performance audit from February 2014 to September 2015 in accordance with generally accepted government auditing standards. Those standards require that we plan and perform the audit to obtain sufficient, appropriate evidence to provide a reasonable basis for our findings and conclusions based on our audit objectives. We believe that the evidence obtained provides a reasonable basis for our findings and conclusions based on our audit objectives. The International Atomic Energy Agency’s (IAEA) INFCIRC/225/Revision 5 international physical security guidelines document provides the basis by which the United States and other countries generally classify the categories of physical protection that should be afforded nuclear material, based on the type, volume, and disposition of the nuclear material. Table 3 lists the material category according to IAEA’s international physical security guidelines. We distributed a data collection instrument to the Department of Energy’s (DOE) Global Threat Reduction Initiative (GTRI), DOE’s Material Protection, Control and Accounting program (MPC&A), the Department of Defense’s (DOD) Cooperative Threat Reduction program, the Department of State, and the Nuclear Regulatory Commission to ascertain what initiative-related work agencies performed and how much that work cost. To that end, the data collection instrument asked agencies to provide a yearly breakdown of all initiative-related spending from fiscal year 2009 through fiscal year 2014, including what work that spending supported, where that work occurred, and how much it cost. The data collection instrument also included questions regarding what agencies planned to spend from 2015 through 2019, and the projects and locations that the spending is expected to support. The data collection instrument also included questions regarding whether agencies had conducted assessments of their data reliability, if they had found any material errors in these assessments, whether the spending figures they were providing were exact or estimates, and—if applicable—how they arrived at the estimates. Our analysis of these data indicates that agencies spent over $1.9 billion in the four key areas of removing, downblending, physically protecting nuclear materials, and converting reactors and facilities that operate on highly enriched uranium (HEU) to low-enriched uranium (LEU), as well as on associated efforts such as training from April 2009 through December 2013. MPC&A spent the most among agencies we surveyed, with over $1 billion spent, mainly on training and other initiative-related activities that fell outside the scope of the four key activities addressed in this report. GTRI spent the next greatest amount, with $553 million, mainly for removals of vulnerable nuclear materials. DOD’s Cooperative Threat Reduction program spent about $329 million. The total amount of spending during the initiative is laid out by agency and activity in table 4 below. Over the course of the initiative to secure vulnerable nuclear materials, the Department of Energy’s (DOE) Global Threat Reduction Initiative (GTRI) removed highly enriched uranium (HEU) and plutonium from around the world, under what may be called the U.S.-origin nuclear material return program, the Russian-origin nuclear material return program, and the Gap nuclear material return program. More specifically, U.S.-origin nuclear material return program. In May 1996, DOE announced it would create a program to allow certain U.S.-origin nuclear materials from Training, Research, Isotope General Atomic (TRIGA) and Material Test Reactor (MTR) reactors, as well as target material containing uranium enriched in the United States, to be returned the United States, subject to certain criteria. The February 1996 Final Environmental Impact Statement conducted to consider the potential environmental impacts of the program noted that fresh, unirradiated HEU would be eligible to return under the proposed program, as well as spent nuclear HEU and in some cases low-enriched uranium (LEU). Russian-origin nuclear material return program. A May 2004 government-to-government agreement between the United States and Russia established the program that returns Russian-origin material to Russia with U.S. government assistance. According to GTRI officials, Russia performs any necessary environmental reviews to facilitate those returns to Russian sites. Gap nuclear material return program. In October 2007, a Secretary of Energy policy memo established the program to provide for the return to the United States of other types of spent nuclear materials not covered in the U.S.-origin nuclear material return program, if the material poses a threat to national security, is susceptible to use in an improvised nuclear device, presents a high risk of terrorist theft, and has no other reasonable pathway to assure security from theft or diversion. Table 5 below lists all removals over the course of the initiative, the site the nuclear materials were removed from, the amount removed, the type of nuclear material, the month and year of removal, and whether the return was made under the U.S.-origin, Russian-origin, or Gap nuclear material program. Over the course of the initiative, the Department of Energy’s (DOE) Office of Global Threat Reduction Initiative (GTRI) helped convert highly enriched uranium (HEU) reactors to low-enriched uranium (LEU), confirmed the shutdown of additional HEU reactors, and converted the production of medical isotope facilities utilizing HEU processes. Table 6 lists the 23 reactors and medical isotope production facilities converted from HEU to LEU or shut down during the course of the initiative, including the country and facility containing the facility. David C. Trimble, (202) 512-3841 or trimbled@gao.gov. In addition to the individual named above, Dan Feehan (Assistant Director), Luke Baron, Antoinette Capaccio, Bridget Grimes, Michelle Munn, Alison O’Neill, and Rebecca Shea made key contributions to this report.

Summary: In April 2009, President Obama announced an initiative to secure all vulnerable nuclear materials—such as those that could be stolen by terrorists and used to construct a nuclear device—within 4 years. DOE is primarily responsible for activities under this initiative, but the Nuclear Regulatory Commission (NRC), the Departments of Defense (DOD) and State, and the National Security Council (NSC) also have roles. GAO was asked to examine actions taken under this initiative. This report (1) assesses the extent to which DOE achieved its goals for four key activities under the initiative and (2) examines DOE's goals going forward and assesses challenges that may limit its ability to secure additional vulnerable nuclear materials. GAO reviewed relevant documents and interviewed officials from DOE, NRC, DOD, and State, as well as discussed these issues with officials from NSC and selected foreign government agencies. This is a public version of a classified report GAO issued in August 2015. The Department of Energy (DOE) achieved goals for two of its four key activities under the President's 2009 initiative to secure all vulnerable nuclear materials within 4 years. Specifically, from April 2009 through December 2013, GAO's analysis of DOE's records found that DOE exceeded its goal for removing or disposing of 1,201 kilograms of highly enriched uranium (HEU) or plutonium by more than 400 kilograms, and it exceeded its goal of downblending (i.e., mixing HEU with either depleted or natural uranium, or low-enriched uranium (LEU), to produce a new product that has a lower concentration of uranium-235) 2,700 kilograms of HEU by an additional 2,200 kilograms. However, it missed its goal for providing physical protection upgrades at 43 buildings by 11 buildings and missed its goal of converting 34 foreign reactors to more proliferation-resistant LEU by 11 reactors. DOE officials said that political challenges, including access to key sites, and technical concerns such as delays in the development of LEU replacement fuels for certain high-performing nuclear reactors, complicated its efforts to achieve these goals. DOE has developed new goals since the end of the 2009 initiative for efforts related to the initiative's four key activities. For example, DOE's goal is to remove or dispose of an additional 1,029 kilograms of fresh and spent HEU, as well as plutonium worldwide from 2014 to December 2019, and convert 27 foreign research reactors and medical isotope production facilities to LEU by the end of fiscal year 2019. However, GAO identified several challenges that may hamper future progress. For example, DOE and other U.S. agencies have not completed an inventory of U.S plutonium overseas as GAO previously recommended in September 2011. DOE and the other agencies did not agree with this recommendation, citing such an effort was impractical and unwarranted. Without such an inventory, the U.S. government is not able to identify where vulnerable weapons-usable materials such as plutonium reside. In addition, DOE has neither completed a prioritization of nuclear materials, including recently identified U.S.-origin HEU, at foreign locations for return or disposition to identify the most vulnerable material stocks to focus efforts on, nor established a time frame for doing so. Another challenge GAO identified is that DOE and other agencies have not visited key sites to determine whether U.S. nuclear material on-site is protected according to international physical security guidelines. Specifically, GAO identified 11 key sites that hold more than 3,500 kilograms of U.S.-origin HEU that DOE and other agencies have not visited in more than 20 years to determine whether they are protected according to international physical security guidelines. DOE has taken steps to develop a methodology for selecting and prioritizing physical protection visits but has not yet provided GAO with a time frame for prioritizing and conducting such visits. Without an assessment of the physical security conditions of U.S.-origin nuclear materials at sites containing key quantities of such material, it may be difficult to ensure that such materials are being adequately protected in accordance with international physical security guidelines, and that DOE and U.S. agencies are removing or disposing of the most vulnerable nuclear materials. GAO continues to believe that DOE and other U.S. agencies should complete an inventory of U.S. plutonium at worldwide sites as GAO recommended in September 2011. In this report, GAO recommends that DOE complete its prioritization of nuclear materials at foreign locations. GAO also recommends that DOE and other agencies visit sites containing key quantities of U.S nuclear materials that have not been visited in at least 5 years. DOE agreed with GAO's recommendations.