Nuclear uncertainties of element yields in the big bang

The abundance of the light elements in the big bang are examined in the context of the uncertainties in the nuclear cross-sections and the number of neutrino pairs. In view of the nuclear uncertainties, the deuterium yield is uncertain by 25 percent, the helium-3 by 40 percent, the lithium-7 by a factor two and the helium-4 abundance by less than 2 percent. The observed abundances of deuterium, lithium-7 and helium-4 are compatible with an universe with a density between 3 and 7 x 10 to the -31 g/cu cm and with two or three low mass neutrino pairs.