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Assessment Methodology for Innovative Nuclear Energy Systems (INPRO Methodology)
International Project on Innovative Nuclear Reactors and Fuel Cycles (INPRO)

Assessment Methodology for Innovative Nuclear Energy Systems (the INPRO Methodology)​

INPRO Methodology
It is important that there be a broadly accepted technical metric defining nuclear energy system (NES) sustainability. This is essential to guide assessments given the long life cycles of nuclear installations, the large capital investment requirements, the lasting technological implications, the inter-generational nature of nuclear waste management and disposition, and the environmental benefits of carbon, particulate and other emissions avoidance. Ultimately, increasing the sustainability of nuclear energy is essential for the maintenance of national stakeholder consensus regarding nuclear energy systems in the long-term.

INPRO developed a set of basic principles, user requirements and criteria, together with an assessment method, which constitute the INPRO methodology, for the evaluation of a national or global NES with regard to its long term sustainability.

The INPRO Methodology covers the six topical areas, that were listed in the UN Brundtland Commission Report and relevant to the assessment of long-term NES sustainability: environmental impacts (resource depletion and stressors),  safety (reactors and fuel cycle), proliferation resistance, waste management, infrastructure (including physical protection), and economics.

The ultimate goal of the application of the INPRO methodology is to check whether the NES assessed fulfils all the criteria and hence the user requirements and basic principles and therefore represents a long term sustainable system for a Member State (or group of Member States). One possible output from an assessment is the identification of areas where a given NES needs to be improved. Given the comprehensive nature of an assessment using the INPRO methodology, such an assessment would be expected to indicate clearly the specific attributes of an NES that need to be improved.

The INPRO Methodology was first published in 2008 as IAEA TECDOC-1575 Rev. 1, in nine volumes (full report). Since 2012, the IAEA TECDOC-1575 has been updated one volume at a time. As of the beginning of calendar year 2020, all INPRO Methodology Manuals have been updated and published or are in the publication pipeline (the manual in the area of proliferation resistance).

Environmental impacts (resource depletion and stressors)

Environmental impact from NES involves two large groups of factors. One group impacting the environment comprises the consumption of non-renewable resources including both fissile/fertile materials necessary to produce nuclear fuel and other materials (e.g. zirconium). All these factors and consumption of electricity necessary to construct, operate and occasionally decommission NES installations are considered in the INPRO methodology manual on environmental impact from depletion of resources. Another group comprises radiological, chemical, thermal and other stressors which NESs release into environment. This group also includes water intake because this factor can be important for biota even when this water is returned to the environment in a clean form (e.g. as steam from nuclear power plant cooling towers). All these factors are considered in this INPRO methodology manual on environmental impact of stressors.

  • IAEA Nuclear Energy Series No. NG-T3.13, 2015 — INPRO Methodology for Sustainability Assessment of Nuclear Energy Systems: Environmental Impact from Depletion of Resources
  • IAEA Nuclear Energy Series No. NG-T3.15, 2016 — INPRO Methodology for Sustainability Assessment of Nuclear Energy Systems: Environmental Impact of Stressors

Safety (reactors and fuel cycle)

The Basic Principles require that the innovative NES enhance the concept of defence-in-depth, with an increased emphasis on inherent safety characteristics and passive safety features resulting in a health and environmental risk of an innovative NES that is comparable with that of industrial facilities used for similar purposes.

  • IAEA TECDOC-1902, 2020, NPRO Methodology for Sustainability Assessment of Nuclear Energy Systems: Safety of Nuclear Reactors
  • IAEA TECDOC-1903, 2020, INPRO Methodology for Sustainability Assessment of Nuclear Energy Systems: Safety of Nuclear Fuel Cycle Facilities

Proliferation Resistance

The Basic Principles associated with proliferation resistance require that intrinsic features and extrinsic measures be implemented throughout the full life cycle of the innovative NES, and that they be optimized, by design and engineering, to provide cost effective proliferation resistance. In an innovative NES, the attractiveness of nuclear materials and technology for diversion to a nuclear weapons programme should be low, and the diversion of nuclear material difficult and detectable.

  • IAEA TECDOC-1575 Rev.1, 2008, INPRO Manual Vol. 5 — Prolifiration Resistance
    (the updated report is being finalized)

Waste Management

The Basic Principles in the area of waste management have been derived from the IAEA Safety Fundamentals concerning "The Principles of Radioactive Waste Management". Thus, the generation of waste is to be kept to the minimum level practicable, securing an acceptable level of protection of human health and the environment without undue burdens on future generations, and all waste generation and waste management steps are to be taken into account.

  • IAEA TECDOC-1901, 2020, INPRO Methodology for Sustainability Assessment of Nuclear Energy Systems: Waste Management

Infrastructure (including physical protection)

INPRO Basic Principle in this area states that a country shall be able to adopt, maintain or enlarge a NES for the supply of energy without making an excessive investment in national infrastructure. The associated User Requirements and Criteria recognize the need to establish a national legal framework and corresponding institutions; adequate economic infrastructure to facilitate availability of credit lines; industrial infrastructure to cover mainly construction, transport and maintenance; socio-political infrastructure to allow long term commitment and public acceptance; appropriate human resources for all steps of the nuclear programme; minimization of the needed infrastructure for a given nuclear power programme; and regional and international arrangements which can be used for minimization of necessary national infrastructure.

  • IAEA Nuclear Energy Series No. NG-T3.12, 2014 — INPRO Methodology for Sustainability Assessment of Nuclear Energy Systems: Infrastructure


This is an assessment of the economic competitiveness of nuclear power, compared with available alternatives. It starts with a short description of the goals and output of energy system planning, followed by general background information on performing an INPRO economic assessment and presents a discussion of the basic principle, the associated user requirements and criteria. Additional background information on economic terms and support tools is provided in the appendices.

  • IAEA Nuclear Energy Series No. NG-T-4.4, 2014 — INPRO Methodology for Sustainability Assessment of Nuclear Energy Systems: Economics