This paper presents the initial provisions, materials, results, current status and next tasks of the study dedicated to the issues of legal and institutional support of transportable nuclear power plants. This study is performed in the framework of the IAEA International Project on Innovative Nuclear Reactors and Fuel Cycles INPRO. Transportable nuclear power plants (TNPPs) are either small nuclear power plants (SNPPs) with their lifecycle implemented on a single transportable platform, or SNPPs assembled of transportable factory-made modules. Advantages of SNPPs and TNPPs are: • Enhanced safety and reliability; • Design simplicity, • Shorter construction period; • Industrial serial production; • Smaller capital costs and shorter investment cycle compared with large NPP; • Possibility of autonomous operation; • Suitability for non-electric application and others. There is an objective evidence of growing interest in developing a nuclear energy system (NES) based on SNPPs including TNPPs. Underlying assumptions of the Russian study: • The User of TNPP services is interested in receiving energy only, does not claim ownership of nuclear technologies, materials and TNPP itself, and this incurs minimal liability for nuclear energy use; INPRO defines this TNPP lifecycle option as “Maximum outsourcing”; • All operations involving nuclear fuel are performed either at the TNPP manufacturer plant, or at a regional TNPP service center within the Holder’s liability zone; • TNPP sitting requires no onsite operations except assembling. Expert reviews have been performed to confirm TNPP lifecycle compliance with the nuclear legislation in fields such as: safety; non-proliferation; nuclear materials’ monitoring, accounting and control; physical protection; and civil liability for nuclear damage; transport operations. It was confirmed that: • In traditional approaches, the existing legal and institutional framework is sufficient for implementing TNPP lifecycle; to achieve the highest efficiency and safety of TNPPs it is necessary to develop TNPPs’ designs, their legal and institutional support; • The following issues are of immediate interest for further studies: combination of inherent safety features and passive safety systems in TNPPs; TNPP lifecycle economy; lifecycle concept without onsite refueling; new approaches to indemnification for nuclear damage; new approaches to physical protection; nuclear liability of TNPP User; remote nuclear materials monitoring, and control and TNPP’ operating; serial industrial fabrication; licensing and certification; public-private partnership; international personnel training system; international cooperation in TNPP fabrication and servicing; role of the IAEA in developing TNPP-based NES. • TNPP/SNPP-based nuclear energy system including all kinds of respective legal, institutional and infrastructural support should become the subject of further studies.