One of the issues that will be discussed at the April 12-13, 2010 Nuclear Security Summit in Washington, DC is the security of weapon-usable nuclear materials. A key material of concern is Highly Enriched Uranium (HEU), which can be used relatively easily to make a simple first-generation weapon.
There are more than a hundred sites worldwide in which HEU is used as reactor fuel. This includes research reactors, critical assemblies and pulsed-power reactors that have lifetime cores that can contain large quantities of barely-irradiated HEU. Ole Reistad and Styrkaar Hustveit of the Norwegian Radiation Protection Authority provided IPFM with an update on the number of HEU facilities that were in operation as of 2009 [UPDATED 04/08/10]:
| Russia & NIS | China | Europe | US | Other | Total | |
| Critical assemblies | 36 | 1 | 4 | 5 | 2 | 48 |
| Pulsed reactors | 16 | 0 | 3 | 3 | 0 | 22 |
| Steady-state reactors (<0.25 MW) | 2 | 3 | 4 | 1 | 11 | 21 |
| Steady-state reactors (0,26 - 1 MW) | 1 | 0 | 0 | 0 | 0 | 1 |
| Steady-state reactors (1,1 - 2 MW) | 0 | 0 | 0 | 0 | 0 | 0 |
| Steady-state reactors (2,1 - 10 MW) | 6 | 0 | 0 | 2 | 1 | 9 |
| Steady-state reactors (>10 MW) | 9 | 0 | 7 | 4 | 0 | 20 |
| Nuclear powered civilian vessels | 11 | 0 | 0 | 0 | 0 | 11 |
| Total | 81 | 4 | 18 | 15 | 14 | 132 |
Notes:
1. The table does not include information on military naval nuclear reactors. Information on military reactors and critical and subcritical assemblies is included to the extent it is available.
2. Reistad and Hustveit are authors of the overview of the HEU use in reactors worldwide, "HEU Fuel Cycle Inventories and Progress on Global Minimization," published in Nonproliferation Review in 2008.
3. [UPDATE 04/08/10: The table updated to include 3 additional Russian HEU reactors - isotope production Ruslan and Lyudmila and the BN-600 fast reactor]