SUBJECT: M.S. Thesis Presentation
BY: Matthew Lynch
TIME: Friday, July 24, 2015, 11:00 a.m.
PLACE: Boggs, 3-28
TITLE: Assessment of Uncertainty in Decay Heat for the Integral Inherently Safe Light Water Reactor
COMMITTEE: Dr. Bojan Petrovic, Chair (NRE)
Dr. Nolan Hertel (NRE)
Dr. Dingkang Zhang (NRE)


The Integral Inherently Safe Light-Water Reactor (I2S-LWR) is a novel uranium silicide (U3Si2) fueled pressurized water reactor (PWR) designed to operate at 2850 MWt/900-1000 MWe. The silicide fuel and different assembly design from a traditional PWR mean that the neutronics, in particular the neutron spectrum, in the I2S-LWR are different from a traditional LWR, and the consequences of these changes are not fully understood.

Owing to the differences from a traditional PWR discussed above, it is not known whether decay heat from used I2S-LWR fuel can be accurately predicted from existing decay heat models, or whether or to what extent it is sensitive to reactor operating conditions.

Using a two-dimensional quarter-assembly model in SCALE 6.1 with zero-current boundary condition, I2S-LWR fuel will be irradiated to varying burnups, with varying operating powers, starting enrichments, and times. ORIGEN will then be used to determine decay heat from used fuel from 1 to 10^10 seconds after discharge.

These results from SCALE depletion and ORIGEN decay heat calculations will then be analyzed to determine sensitivity to the above-described variables, and the results will be benchmarked against decay heat from a traditional PWR, and the ANS Standard ANS 5.1-2014, "Decay Heat Power In Light Water Reactors".