The report gives results of a program to complete the preliminary design of a three-stage combustion (reburn) system for nitrogen oxide (NOx) emissions control on an operating boiler in the U.S.S.R. The program to design the reburn system consisted of five tasks: visiting the Ladyzhinskaya host site to exchange design and operating information; translating Soviet documents into English; performing process calculations; conducting physical flow modeling; and developing a preliminary system design which included general arrangement drawings and furnace performance analyses. The overall preliminary reburn system design was presented to and accepted by Soviet representatives during a June 1989 meeting at the EPA's Air and Energy Engineering Research Laboratory in Research Triangle Park, NC. It appears that reburning would be a viable NOx reduction technology for the type of boiler represented by the host Ladyzhinskaya steam generating unit.