fuck no, currently most important isotopes are cs-137 and sr-90, both with half lives about 30 years. plutonium isotopes have half lives from 14 (241; probably tiny amount) 90 (238; also not much) to thousands of years (239 and 240; most likely bulk of it). what did the most damage in chernobyl were even shorter lived (days) and so spicier isotopes that normally are given time to decay in spent fuel pools