[en] Long-term operating NPP reactor pressure vessels (RPV) are subject to the multi-factor influence. It is practically impossible to reproduce some of these factors (time, e.g.) in the frame of experimental investigations including surveillance specimens' study. Detailed information that can result from taking samples immediate from the decommissioned and operating RPVs is more reliable than received by any other ways and therefore should be of a highest value. Prototype NPP RPVs embrittlement analyses have shown that compensation of the degrading neutron influence by radiation gamma-annealing is taking place. This phenomenon opens the perspective of neutron effects mitigation and life cycle management using the control of neutron and gamma ray radiation fluxes. (author)