Within the framework of an European Commission sponsored activity, an assessment of the deterministic safety technology of the ‘post-Chernobyl modernized’ Reactor Bolshoy Moshchnosty Kipyashiy (RBMK) has been completed. The accident analysis, limited to the area of Design Basis Accident, constituted the key subject for the study; events not including the primary circuit were not considered, as well as events originated from plant status different from the nominal operating conditions. Therefore, the notorious Chernobyl Unit 4 event was outside the scope of the investigation. Following the evaluation of the current state of the art in the area including the identification of critical issues, targets for the analysis were established together with suitable chains of computational tools. The outcomes from this part of the study are (a) the list of transient scenarios whose parameter values are assumed to constitute the boundaries for the evolution of any relevant safety transient and; (b) a set of computational tools with characteristics consistent with current technological achievements, suitable for performing safety analyses. The availability of computational tools, including codes, nodalisations and boundary and initial conditions for the Smolensk 3 NPP, brought to their application to the prediction of the selected transient evolutions that, however, are not classified as licensing studies. The results demonstrated proper safety margins and relatively long time constants associated with the huge values for the ratios between mass of moderator and mass of coolant and unit generated power. The results at the item above, suggested a qualitative, though non rigorous, comparison between accident analysis aspects in LWR and RBMK having the main purpose to show strengths in RBMK safety features heavily criticized not always in a consistent way following the Chernobyl event. The results of supporting analyses for the present paper are discussed in five companions papers in this Journal volume. The second (over six) and the third paper deal with the RBMK Main Coolant Circuit and Confinement thermal-hydraulic performance, respectively. Key specific issues in the RBMK safety technology, constituted by addressing of the “Multiple Pressure Tube Rupture (MPTR)” and by the application of coupled three-dimensional neutron-kinetics thermal-hydraulics, are discussed in the fourth and fifth papers. The proposal to instrument the core channels (ICM = Individual Channel Monitoring) has been formulated in this context and is discussed in the sixth companion paper.
Deterministic accident analysis for RBMK
D'AURIA, FRANCESCO SAVERIO;
2008-01-01
Abstract
Within the framework of an European Commission sponsored activity, an assessment of the deterministic safety technology of the ‘post-Chernobyl modernized’ Reactor Bolshoy Moshchnosty Kipyashiy (RBMK) has been completed. The accident analysis, limited to the area of Design Basis Accident, constituted the key subject for the study; events not including the primary circuit were not considered, as well as events originated from plant status different from the nominal operating conditions. Therefore, the notorious Chernobyl Unit 4 event was outside the scope of the investigation. Following the evaluation of the current state of the art in the area including the identification of critical issues, targets for the analysis were established together with suitable chains of computational tools. The outcomes from this part of the study are (a) the list of transient scenarios whose parameter values are assumed to constitute the boundaries for the evolution of any relevant safety transient and; (b) a set of computational tools with characteristics consistent with current technological achievements, suitable for performing safety analyses. The availability of computational tools, including codes, nodalisations and boundary and initial conditions for the Smolensk 3 NPP, brought to their application to the prediction of the selected transient evolutions that, however, are not classified as licensing studies. The results demonstrated proper safety margins and relatively long time constants associated with the huge values for the ratios between mass of moderator and mass of coolant and unit generated power. The results at the item above, suggested a qualitative, though non rigorous, comparison between accident analysis aspects in LWR and RBMK having the main purpose to show strengths in RBMK safety features heavily criticized not always in a consistent way following the Chernobyl event. The results of supporting analyses for the present paper are discussed in five companions papers in this Journal volume. The second (over six) and the third paper deal with the RBMK Main Coolant Circuit and Confinement thermal-hydraulic performance, respectively. Key specific issues in the RBMK safety technology, constituted by addressing of the “Multiple Pressure Tube Rupture (MPTR)” and by the application of coupled three-dimensional neutron-kinetics thermal-hydraulics, are discussed in the fourth and fifth papers. The proposal to instrument the core channels (ICM = Individual Channel Monitoring) has been formulated in this context and is discussed in the sixth companion paper.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
