Carbon-14 production in nuclear reactors

Quantities of 14C that may be formed in the fuel and core structural materials of light-water-cooled reactors (LWRs), in high-temperature gas-cooled reactors (HTGRs), and in liquid-metal-cooled fast breeder reactors (LMFBRs) have been calculated by use of the ORIGEN code (Be73). Information supplied by five LWR-fuel manufacturers pertaining to nitride nitrogen and gaseous nitrogen in their fuels and fuel-rod void spaces was used in these calculations. Average nitride nitrogen values range from 3 to 50 ppM (by weight) in LWR fuels, whereas gaseous nitrogen in one case is equivalent to an additional 10 to 16 ppM. Nitride nitrogen concentrations in fast-flux test facility (FFTF) fuels are 10 to 20 ppM. The principal reactions that produce 14C involve 14N, 17O, and (in the HTGR) 13C. Reference reactor burnups are 27,500 MWd per metric ton of uranium (MTU) for boiling water reactors (BWRs), 33,000 MWd for pressurized water reactors (PWRs), about 95,000 MWd per metric ton of heavy metal (MTHM) for HTGRs, and 24,800 MWd/MTHM for an LMFBR with nuclear parameters that pertain to the Clinch River Breeder Reactor