Experimental Research On The Minimum Spray Flux For Cooling Of Spent Fuel Rods With Low Decay Heat In PWR

Safety of spent fuel pool has been paid much attention since Fukushima nuclear accident. Spray cooling system is firstly added in spent fuel pool of API 000 to deal with accidental vent of spent fuel pool and bareness of spent fuel assembly beyond design basic accidents, and then temperature of clad can be limit with safety by absorbing heat and evaporation of spray water to take away decay heat of spent fuel assembly. Spent fuel rod is small diameter and great height, cooling effectiveness is affected by decay heat, Spray flow, Spray Angle and granularity. Besides, spray cooling involves evaporation, phase transition and vapor-liquid counter flow, it’s a very complex physics process. By now credible results cannot be gotten by analog computation. So, it’s necessary to research influencing factors of spray cooling to provide technical support for design of spray cooling system in Nuclear Power Plant. A set of spray cooling experimental device for spent fuel pool is advanced which can research effects of spray cooling. Electrically heated rods 5x5 are used to simulate spent fuel rods of spent fuel pool in Nuclear Power Plant, and then change heating power to get different minimum spray flows when temperature of clad is kept in 300 ℃. Besides, change nozzle types to gain different granularity of spray water to research its influences on spray cooling effects for spent fuel pool. The results show that granularity of spray water has great effect on minimum spray flow.