Seeding pseudo random generator with random number from a better random source

Let's say we have a pseudo random number generator that accepts a 32 bit integer as seed (for example the rand() function from the C standard library), which derives random numbers from the original seed. If that seed were to come from, let's say, radioactive decay, is it correct to assume that the random number we get from calling rand() is as "good" random number as taking generating one from radioactive decay?