This paper presents a method for function analysis and (re)allocation of MTO (Man, Technology, Organization) systems that are affected by or depending on IO (Integrated Operations) across organizational and physical units within the system. The method, called IO MTO, is in fact already well-applied within the petroleum industry in Norway, for which the IO specific factors have gradually but firmly become profoundly significant. As it is believed that the IO specific problems will also find their ways into the nuclear domain, among others, as a result of many modernization activities at NPPs worldwide, the authors are of the opinion that the method will demonstrate its relevance and applicability also for the nuclear industry. The paper attends to challenges towards topics and aspects less covered by the method, thus emphasizing its potentials for possible further improvements or for combination with other methods and techniques. A section is dedicated to matters of concern related to dependability (with explicit focus on safety, reliability and security) of current and future IO-driven MTO systems at NPPs, that indeed might necessitate a specialization of the method.