Analysis of Benefits and Risks of Thorium and .sup.233U Introduction in the VVER-1200 Fuel Cycle in the Fusion-Fission Reactor System

The limited amount of economically suitable natural uranium resources forces us to improve the existing structure of the nuclear power system and its fuel cycle. With the current natural uranium reserves, it becomes practically impossible to significantly increase nuclear power plant (NPP) capacities in the existing system on the basis of thermal reactors operating in the open nuclear fuel cycle (ONFC). In order to solve this problem, the article considers the introduction of fusion-fission reactors (FFRs). FFR blankets produce .sup.233U, which is further utilized in thermal reactors. In this article, fuel compositions of VVER-1200 reactors with the addition of .sup.233U and thorium are studied, which make it possible to reduce the consumption of natural uranium and/or utilize already available raw materials in the form of depleted and regenerated uranium. On the basis of the scenario of the Russian nuclear power system (NPS) development within the ONFC with VVER-1200 reactors, the required .sup.233U production volumes and the corresponding FFR fraction are determined for all fuel options. The risks of thorium introduction into the nuclear fuel cycle (NFC) are reviewed.