Plant integration of MITICA and SPIDER experiments with auxiliary plants and buildings on PRIMA site

•Focus on plant integration work supporting the realization of SPIDER and MITICA fusion experiments hosted in PRIMA buildings complex in Padova, Italy.•Huge effort of coordination and integration among many stakeholders, taking into account several constrains coming from experiments requirements (on-going) and precise time schedule and budget on buildings construction.•The paper also deals of interfaces management, coordination and integration of many competences, problems solving to find best solution also considering other aspects like safety and maintenance. This paper presents a description of the PRIMA (Padova Research on ITER Megavolt Accelerator) Plant Integration work, aimed at the construction of PRIMA Buildings, which will host two nuclear fusion test facilities named SPIDER and MITICA, finalized to test and optimize the neutral beam injectors for ITER experiment. These activities are very complex: inputs coming from the experiments design are changing time to time, while the buildings construction shall fulfill precise time schedule and budget. Moreover the decision process is often very long due to the high number of stakeholders (RFX, IO, third parties, suppliers, domestic agencies from different countries). The huge effort includes: forecasting what will be necessary for the integration of many experimental plants; collecting requirements and translating into inputs; interfaces management; coordination meetings with hundreds of people with various and different competences in construction and operation of fusion facilities, thermomechanics, electrical and control, buildings design and construction (civil plants plus architectural and structural aspects), safety, maintenance and management. The paper describes these activities and also the tools created to check and to validate the building design, to manage the interfaces and the organization put in place to achieve the required targets.