Or in your case, drop the second line entirely.
vanillaHD.hr_tint_mask["nuclear-loader"] = {r = 0, g = 141, b = 5} is now redundant.
You would want:
vanillaHD.tint_mask["nuclear-loader"] = {r = 0, g = 141, b = 5}
vanillaHD.createLoaderItem("nuclear-loader","uranium-transport-belt")
vanillaHD.createLoaderRecipe("nuclear-loader","uranium-transport-belt","express-loader")
vanillaHD.createLoaderEntity("nuclear-loader","uranium-transport-belt")
vanillaHD.patchLoaderTechnology("uranium-transport-belts","nuclear-loader")
data.raw.item["nuclear-loader"].flags = {}