Your question is rather loaded. How about carbon dating is not affected if we calibrate for the original d14C. Nuclear tests have increased the 14C count but so does randomly increased cosmic radioactivity, the massive release of 14C depleted fossile fuel has decreased the 14C ratio but so has massive discharge of oceanic CO2 in the past.
Nowadays carbon dating has been calibrated using dendrochronology (tree rings) and lacustrine varve (lake sediment layers) counting all the way to its maximum usuable extend of some 50,000 years. Carbon dating may be considered reliable now but there are big error margins. The indicated problems make carbon dating rather unusable for the last 300 years. Also between about 9000 and 11000 years ago there are large margins due to massive CO2 release.