Nuclear Thermal Hydraulic System Experiment Nuclear and Hydrogen System Laboratory, KAIST 2015.05.28

Fukushima accident Earth quake  Reactor shut down Electricity supply from grid is failed Emergency diesel generator is also failed Submerged by Tsunami Reactor Coolant Pump is turned off Thermal energy couldn’t be removed Most of safety systems were dependent on electricity Fuel melt / Hydrogen explosion / heat up of spent fuel pool

Nuclear Safety Systems Systems that required to remove the decay heat under the postulated accident ex ) Safety Injection system (Inject water to the primary loop during accient) After Fukushima, following requirement were added to the safety systems System should remove the decay heat even without electricity We call this system as “Passive safety system” Usually gravity is used for the driving force of passive safety system

Nuclear Power Plant accident A number of systems (Thermal hydraulic systems) Thermal Energy From Fuel rod (from atomic decay) “Decay heat” Electric Energy Fuel rods Heat should be removed Safety system

Passive Containment Cooling System Passive system that removes decay heat by cooling the steam/air in the containment Decay heat (Steam) Decay heat How can we measure and calculate the performance of this system  Experiment for PCCS

PCCS Test Purpose To calculate heat removal capacity and heat transfer coefficient of the condensing tube Check the effect of the Air/Steam Fraction Check the effect of the Pressure

PCCS Test Facility Main test section Chambers : Heat exchangers Steam Generator PCCT and Cooling water pipes Chamber : Air/Steam mixture SG PCCT

Experiments Procedure 1. Set up test condition Steam pressure of the steam generator Angle of the condensing tube (Already Fixed) Temperature of cooling water (inlet) Mass flow rate of cooling water 2. Open the valve of SG connected to the chamber 3. Measure or set the properties of system System pressure and temperature Outlet temperature of cooling water 4. Calculate heat capacity and heat transfer coefficient 5.Open the venting valve on the chamber for 1 min and close it Air/Mass Fraction of the System changed ( for next Exp. Case.) 6.Repeat previous steps

Experiments Procedure Steam generator 2 ,3 and 4 bar saturated condition (one pressure condition for one group) Cooling water Pressure: 1 bar(atmosphere) What you measure? Or check? Temperature of cooling water in / out Mass flow rate Twall Channel geometry information Outer diameter of pipe = 49.1 mm Inner diameter of pipe = 40 mm Length of pipe = 0.7 m

Heat transfer rate and heat transfer coefficient Heat transfer rate : Amount of heat transferred per time Single-phase fluid ** Mass flow rate,

Heat transfer rate and heat transfer coefficient Heat transfer coefficient : Amount of heat transferred per time, per area, and per temperature difference Twall Tbulk Heat transfer coefficient is affected by : Geometry / Angle / Materials / Air-mass fraction / Pressure ….

Heat transfer rate and heat transfer coefficient Heat transfer rate : Amount of heat transferred per time Single-phase fluid

Notes Your Report Should includes Clear Conditions for each case Air / Steam Fraction of each experiments (Through the calculation) Heat Transfer Coefficient of PCCS for each case and the reason for the difference between each case.