Generic Feasibility Assessment

Generic Feasibility Assessment (GFA)

Welcome to GFA, now updated for 2026!

GFA is a tool which aims to help policymakers understand the challenges and benefits between different types of nuclear reactor system. It considers broad relative advantages and challenges between general reactor types (e.g. how does a generic PWR compare to a generic HTGR); not how individual reactor designs compare with each other (e.g. how does PWR x perform versus PWR y).

GFA considers six broad reactor system types, assessed relative to a Small Modular Reactor (SMR) reference system, specifically a generic small modular pressurised water reactor. The six systems assessed by GFA are:

  • Gigawatt-scale Pressurised Water Reactor (GW-PWR)
  • High Temperature Gas-cooled Reactor (HTGR)
  • Thermal Molten Salt Reactor (MSR)
  • Sodium Fast Reactor (SFR)
  • Lead Fast Reactor (LFR)
  • Molten Salt Fast Reactor (MSFR)

GFA uses an easy to understand grid system (Figure 1) to display the strengths and weaknesses of up to two systems compared to a reference system. Systems have been assessed across a range of attributes, which have been combined into 12 "Strategic Attributes". Beneath each Strategic Attribute (represented in GFA as circles) are one or more Discriminators (represented as squares) which inform the Strategic Attribute rating.

An example of a typical GFA output.
Figure 1. Example GFA Output.
Up to two systems can be chosen for display. This example shows the 'Waste Storage and Disposability' Strategic Attribute and its underlying Discriminator metrics.

Which attributes are most important change over time, so GFA does not weight its attributes, instead allowing users to make that value judgement themselves.

GFA was developed as part of Project 3 for a 2016 Department of Energy and Climate Change independent Techno-Economic Assessment of SMRs, following Phase One of the 2016 SMR Competition. In 2025 GFA was moved online to improve accessibility and in 2026 workshops were held to update the assessments from the 2016 edition. The updated tool was made available online in June 2026. The 2016 edition of GFA is still available at the link at the bottom of this page.

Please not that this website is not optimised for mobile devices, so the use of a desktop computer is recommended.

Click here to start using GFA

Background to GFA

Multi-Attribute Decision Analysis (MADA)

MADA is the common method of comparing complex systems. In this method a group of attributes are defined to cover the main parameters of the systems, and scores are allocated depending on how well or badly a system performs. For an automotive example, a supermini might score well on "fuel economy", whereas an off-road 4x4 would likely score badly. Not all parameters carry the same importance: "Engine reliability" will likely be judged to be more important than the "range of paint colours available" for each vehicle type. Compiled scores are therefore weighted accordingly and these weighted scores combine to provide an overall consolidated score for the systems being compared. A subsequent large increase in fuel prices would likely shift the priorities of users, but a fixed MADA would not reflect such a change. GFA seeks to avoid weightings to enable users to apply their own priorities.

NNL Assessment of Nuclear Technologies

In 2012/3, the National Nuclear Laboratory (NNL) developed a methodology to examine nuclear power systems, based on 42 metrics derived from those used by the Generation IV International Forum. These were subsequently divided into seven groups (Cost, PRPP, Safety, Strategic, Deployability, Sustainability, Waste) and used to assess advanced reactor systems. While the scores from these analyses defined winners and losers, the approach suffered from two main disadvantages:

  1. The use of a MADA with a large number of metrics makes the result very difficult to communicate meaningfully, even to committed stakeholders.
  2. The suitability of a reactor system depends very strongly on the world in which it must operate. For different times and locations, the suitability will vary. For example, systems which score highly for uranium economy (e.g. fast reactors) should be highly weighted in a future with limited uranium supply, but less so in a future where uranium is plentiful and cheap.

Development of GFA

Following this, collaborative efforts from the Dalton Nuclear Institute, Integrate Decision Management (IDM) and NNL evolved GFA. The system data from the complex NNL analyses are utilised, but are accumulated into a more useable number of Strategic Attributes (12), and are assessed by pairwise comparison to a reference system. This was initially to be a contemporary Pressurised Water Reactor (PWR) with a once-through cycle, for which many of the parameters were already well understood.

The comparisons made are based on published data which can be referenced, linked and made publicly available. The result is an analysis which relies on easily assimilated graphics and words, rather than complex and opaque marking systems.

GFA has been applied to several advanced reactor systems, and was deployed most recently to assess Small Modular Reactors (SMRs) as part of the 2016 Independent Techno-Economic Assessment (TEA) of SMRs for the Department of Energy and Climate Change. The final report was supported by an extensive literature review of the subject area.

GFA in 2026

The 2016 GFA tool is available here, and has been transferred from its original format to this openly available browser version which we hope is more accessible to users. GFA was updated in June 2026. Those interested in comparisons with the 2016 GFA should be aware that some assessments may be outdated, and some terminology has moved on since 2016.

Further Information