Three Mile Island-2 Accident Analysis with RELAP5/SCDAP Code
S. L. Sharmaa, P. Krishna Kumarb, H. P. Rammohanc, P. K. Malhotrad, S. G. Ghadgee
and Umesh Chandraf
NPCIL, Mumbai 400 094, India.
aslsharma@npcil.co.in
bpkrishnakumar@npcil.co.in
chprammohan@npcil.co.in
dpkmalhotra@npcil.co.in
esgghadge@npcil.co.in
fumesh@npcil.co.in
ABSTRACT
This work is a part of joint exercise between AERB and USNRC. Objective was to analyze TMI-2 severe accident scenario with current state of art. SCDAP/RELAP5 code was chosen for this purpose as this code has well validated models for accident analysis of light water reactors. TMI-2 Model included detailed modeling of primary circuit, pressuriser, reactor vessel, Once Through Steam Generators. Thermal hydraulics is simulated with RELAP5 whereas core modeling is done with SCDAP. Primary side makeup and letdown flow rates, pressuriser PORV opening and closings and heater on/off, steam generator secondary side coolant levels, pressures, and feedwater temperatures were supplied as boundary conditions. All the four phases of the accident (first 300 min. of accident) were simulated. In all the phases results were in general agreement with the measured and observed data. Code well captured core uncovery, heatup, melting and molten pool formation. In phase 1 and phase 2 trends and magnitude of calculated data compared well with the measured/observed data whereas in phase 3 and 4 trends were matching.
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