Design features and thermal margin assessment of core protection and monitoring systems of an integral reactor, SMART

The Korea Atomic Energy Research Institute has developed the SMART integral reactor, and SCOPS and SCOMS were also newly developed as advanced real-time core protection and monitoring systems for SMART. SCOPS calculates the minimum DNBR and maximum LPD based on several on-line measured core state parameters, and SCOMS calculates the limiting conditions for operation variables and assists the operator in implementing the technical specification requirements for monitoring. The design features and characteristics of SCOPS and SCOMS were described. The performance of the SCOMS power distribution synthesis method was evaluated and shows negligible power distribution synthesis errors. A technically reliable uncertainty analysis method was developed, and a preliminary uncertainty analysis was evaluated. The overall analysis results are similar or more improved compared to those of cycle 1 for Younggwang units 3 and 4 of Korea. In particular, uncertainty factors of SCOMS are much improved because of an improvement in the power distribution synthesis and DNBR calculation algorithm. Finally, thermal margins were estimated, and the DNB overpower margin of SCOMS is large enough to accommodate a 40% required overpower margin and 15% top-tier requirement thermal margin. (author)