gt – mhr reactor cavity cooling system. rccs conduction – radiation – convection rccs-snu:...

GT – MHRReactor Cavity Cooling System

RCCS

Conduction – radiation – convection

RCCS-SNU: water-pool type RCCS-- water natural convection-- air force convection

“Heat Transport and Afterheat Removal for Gas Cooled Reactors Under Accident Conditions”, IAEA-TECDOC-1163, 2000.

Seoul National University

Y.J. Cho, M. O. Kim, G. C. Park, "Measuring Characteristics on Emissivity Using Infrared Thermometer for RCCS," NTHAS4: Fourth Japan-Korea Symposium on Nuclear Thermal Hydraulics and Safety, Sapporo, Japan, November 28-December 1, 2004

Heat removal mechanisms from RPV to cavity: – Thermal radiation (~80%)– Convection (~20%)

RCCS heat removal mechanisms:Active cooling: air forced-convectionPassive cooling: water boiling heat transfer &

air natural convection

1. Accident fuel temperatures are insensitive to RCCS performance2. Vessel temperatures are more sensitive to RCCS performance but still not a strong function3. Reactor cavity concrete temperatures are a strong function of RCCS performance

Conclusion from Idaho Nation Laboratory May 24 – 27, 2010

Pool type RCCS Example

Side tank & 12 pipes with one loop meshed

12 Bended pipe vs. straight pipes ?

Experiment

(a) Upper tank of the test facility (b) Side water tank

Schematic diagram of the test facility

Detail dimensions

(80% radiation 20% conduction)

• 1/10 linear scaled 1/1000 volume.• 1/100 power scale.• Heat flux is preserved in the proto and model • Time scale is reduced to 1/10.• Axial distribution of temperature in water pool

is not considered.• Scaling analysis is carried out to derive the

similarity criteria of RPV temperature.

1. Constant heat flux2. Heat flux distribution3. Cavity natural circulation(20%, 50%, 80%

Helium)4. Boiling heat transfer of water pool5. Air natural convection (chimney height)