NESSAT v6: your toolbox to assess nuclear energy system futures

Nuclear-21’s integrated assessment toolbox NESSAT, i.e. Nuclear Energy System Strategies Assessment Toolbox, knows a continuous development enriched by our own developments and responding to our client’s requests to assess specific questions relating to present and future nuclear energy system performances regarding a variety of objectives and criteria.

Composed of five essential tools, NESSAT  is being used to assess the market potential for new nuclear power plants while allowing to perform in-depth analysis of intra-nuclear system options, e.g. combining multiple reactor technologies and their associated fuel cycles and waste arisings. Our latest version includes new functionalities in the NucInfo database and particularly in DANESS being the true kernel model of the NESSAT toolbox.

The NucInfo database captures the information from the past, present and projected futures on all nuclear reactors, fuel cycle facilities and inventories on a country-per-country basis while also documenting existing and especially also new reactor and fuel cycle technologies. This information being particularly of value to provide best-available information in performing integrated technical-economic-environmental studies using the DANESS model. DANESS, i.e. Dynamic Analysis of Nuclear Energy System Strategies, simulates on very detailed level all mass-flows and inventories in time-evolving nuclear system from U/Th-mining until final radioactive waste disposal. The latest DANESS version has been improved with specific advanced functionalities as, to name the most important ones:

  • The waste management impact has been further detailed allowing to assess the footprint for the different types of radioactive waste to be disposed of;
  • Reactor physics modelling has been extended for MSR-options where a specific new reactor physics modelling using Reduced Order Model methodologies (as developed by TU Delft) has been integrated and be extended to a variety of reactor technologies;
  • Multi-recycling scenarios analysis with Pu and/or REPU-driven reprocessing and recycling schemes which are under consideration in a variety of studies by our clients and in international projects.

NESSAT allows:

  • from the early phases of considering nuclear energy use, to analyse and project the role for nuclear energy in your future energy mix and allowing you to perform ‘what if?’ technical-economic scenario analysis among the different nuclear power plant options, their associated fuel cycle and waste management performances. You can, for instance:
    • perform energy market analysis using the DEMA-model (Dynamic Energy Market Model) allowing to perform a full energy market analysis covering electricity and non-electricity uses;
    • project the required human skills to be developed in your nuclear energy programme enriching the timely strengthening of your nuclear energy programme;
    • perform scoping techno-economic analysis of nuclear power plant options and, once deployed, their fuel cycle and waste management requirements and impacts;
    • NESSAT also provides you access to the global nuclear energy performance, country-per-country and reactor-per-reactor, providing you ample information to support your communications on your nuclear energy programme. Non-nuclear energy conversion technologies are also reported providing you a authoritative set of information to enrich your communication without bias.
  • once a nuclear energy programme has been decided, NESSAT assists you in detailing the intra-nuclear options in detail providing you the technicaleconomic descriptions of past, present and future nuclear power plant technologies, fuels and fuel cycle and waste management technologies or services that you might need to consider for deployment or contracting. You can, for instance:
    • perform comparative analysis of large liwght-water reactor (LWR) technologies with small modular reactor (SMRs) or even advanced modular reactors (AMRs) or Gen-IV reactors with regard to energy market requirements, economic competitiveness and investment analysis next to assessing options for the fuel and fuel cycle to be deployed. Importantly, the projected waste arising and its financial provisioning is also analysed allowing already, early on and in an integrated way, to optimise your nuclear energy policy;
    • test and support your contractual positioning with regard to nuclear power plant investments as well as fuel cycle services.
  • NESSAT provides you an integrated model for your nuclear power programme simulating one up to a time-evolving park of nuclear power reactors and their associated front-end and back-end fuel cycle service and waste management needs. Throughout the lifetime of your nuclear energy system, NESSAT can provide a detailed mass-flow and inventory analysis from U/Th-mining until final disposal allowing to have an integrated view on your nuclear energy system from a technical, economic, environmental and strategic perspective all this in one coherent environment visualised via performing InfoGraphics. You then can test new developments in “What If?”-scenarios assessing the impact new technologies or regulatory requirements may have on your overall system performance and/or assessing the technical-economic interest to pursue some of the options. Questions relating to the role for and impact from SMRs are typically also addressed by such integrated modelling. The options may well be very operational, e.g. deciding upon the pool-to-pad transfer of used fuels, or the most appropriate front-end fuel cycle contracting, next to preparing more strategic options as extending used fuel storage capacity or switching to (multi-)recycling scenarios including more advanced nuclear systems as AMRs and Gen-IV’s.
  • A unique capability of NESSAT being to assess the financial risks from and in your nuclear energy system and to assess the impact these have on your decisional options, e.g. how to minimise/optimise costs and financial risks in uncertain market futures relating to, f.i., energy market, uranium market, waste management and advanced nuclear technology developments. The NROM-model (Nuclear Real Options Model) uses advanced financial evaluation methodologies as real options valuation to analyse the investments in new nuclear technology or nuclear power plants, or to decide on fuel cycle and waste management options, in uncertain (technicaleconomic-policy-market)conditions over the timelines required to deploy these options. NESSAT and NROM then allow to answer questions alike:
    • What value brings modularity in the deployment of SMR/AMRs in energy markets?
    • How to decide on back-end fuel cycle policies in light of uncertain cost and timeline for geological disposal?
    • How to mitigate the financial risks from such uncertain waste management deployment?
    • What is the economic value to keep a fuel cycle option open, e.g. extending pool storage awaiting, though very uncertain, a future. option to switch to reprocessing of used fuel?
    • How does multi-recycling of Pu in LWRs compare to Gen-IV/FR multirecycling scenarios and does such intermediate phase in LWRs brings economic value?

More information can be obtained via where a full-fledged information website ( with examples of applications of NESSAT will become available from mid-Oktober ’23 on.