METHOD FOR EVALUATING STEAM VOID COEFFICIENT OF REACTIVITY Russian patent published in 2008 - IPC G21C17/00 

FIELD: controlling and regulating nuclear safety characteristics and parameters of nuclear power station reactor units.

SUBSTANCE: proposed method for evaluating steam void coefficient of reactivity at nuclear power stations incorporating heavy-power pressure-tube reactors, type RBMK, includes check-up of neutron-physical and heat-hydraulic parameters of reactor unit, selection of processes involving variation of feedwater flowrates in steam separator drums as result of operation of automatic water-level regulators, and calculation of steam void coefficient of reactivity in processing data characterizing reactivity balance in mentioned processes. Novelty is that parameters characterizing reactivity balance are recorded under standard conditions of local automatic reactor-power control (LAC) in selecting processes involving variations in feedwater flowrate while considering events accompanied by movement of control and protection system rods, steam void coefficient of reactivity being calculated from set of equations of following type: α_WΔW_k + α_φΔφ_k(Δi_in) + ρ_cps,k = ρ_fin.n_.k ρ_in.k, (k = 1,... K), where α_φ is steam void coefficient of reactivity; α_W is power coefficient of reactivity concurrently found in solving set of equations; ΔW_k is steady state heat power variation recorded during flowrate disturbance in the course of k chosen process; Δφ_k(Δi_in) is `variation in void fraction due to coolant enthalpy variation at core inlet; ρ_cps,k is abrupt change in reactivity caused by displacement of automatic power regulator rods; ρ_in.k,_{ρfin.k is initial and final reactivity of reactor, respectively.}

EFFECT: enhanced operating reliability and safety in checking steam void coefficient of reactivity, enhanced precision of checking this parameter responsible for safety of nuclear reactor unit.

1 cl, 2 dwg