Improvement of the System for Passive Heat Removal Through Steam Generators (SG PHRS) on NPP With VVER-1200 in the Light of “Fukushima” Accident

Abstract

As a result of catastrophic events on the nuclear power plant “Fukushima” the European organizations on regulation of nuclear power (ENSREG) initiated wide-scale measures for complex designs revision of already operating and under construction European and Russian NPPs. Inspection was made about resistance of power units to external influences of the natural character, being accompanied by multiple failures of safety systems. Within these works stress tests for constructed power units of LAES-2 and the Baltic NPP were executed. The structure of these checks included the settlement analysis of a condition of NPP at accident with loss of all AC power supply sources which results are presented in report materials. Accident calculations with a full blackout were executed on the best-estimated heat-hydraulics code KORSAR/GP for justification of power unit preservations in the intact condition within 72 hours from the accident beginning by means of SG PHRS. The system is developed for feed of the SG PHRS tanks and the fuel pool for working capacity extension the SG PHRS and power unit preservation in a stable condition more than 72 hours from the accident beginning. Use of system for feed of tanks the SG PHRS and the fuel pool allows to increase significantly resistance of the NPP to external influences of the natural character and to increase time of preservation of the blackout power unit in a stable condition more than 5 days.

Experimental Investigation in Improving Thermal Performance of Passive Heat Removal System using Mist Assisted Evaporative Cooling

“…After Fukushima Daiichi disaster, the passive heat removal system PHRS become very important in nuclear power plants NPPs to improve the safety and reliability of the nuclear reactors. The PHRS is aimed to protect the primary circuit by removing the decay heat from the reactor core in an emergency shutdown or blackout conditions [1]. In the Water-Water Energetic Reactor-WWER or VVER design, the PHRS system comprises of four independent coolant circuits, each one involves heat exchange modules, air gates, steam pipelines and air ducts to supply the ambient air and bleed the heated air as shown in Figure 1.…”

The Estimated Duration of Effective Operation of the Autonomous PHRS, Comparing the Heat Sink to Cooling Water vs Ambient Air

“…В частности, отечественными проектами СПОТ ПГ предусмотрено два варианта отвода те-плоты от ТК: к атмосферному воздуху -проекты Московского института «Атомэнергопроект» РУ с ВВЭР-1000/В-412 [1], АЭС-2006 с РУ ВВЭР-1200/В-392М и ВВЭР-ТОИ [2], а также к выки-пающей воде, размещенной в баках аварийного отвода теплоты (БАОТ), -проекты Санк-Петер-бургского института «Атомэнергопроект» РУ с ВВЭР640/В-407 [3] и РУ с ВВЭР-1200/В-491 [4].…”