An expert mission of the International Atomic Energy Agency (IAEA) has started in the Bulgarian NPP Kozloduy. The mission has been invited by the Agency for Nuclear Regulation and by the government following a request of the NPP, to assess the fulfillment of the program for upgrading of its Russian VVER 1000 reactors. The program has been implemented stage-by-stage during repair works in 2002 and 2007.