Loss-of-fluid Test (LOFT) Project
Joint project

View looking down onto the LOFT reactor


The Loss-of-fluid Test (LOFT) Research Programme was originally set up by the US Nuclear Regulatory Commission. Part of the programme was later broadened into an international collaboration project under the aegis of the Nuclear Energy Agency (NEA). This initial programme addressed several configurations of loss-of-coolant accident (LOCA) with large break tests and intermediate break tests carried out between 1978 and 1982.

The new programme, subject of the NEA's LOFT Project, was designed to use the LOFT experimental nuclear test facility at the Idaho National Engineering Laboratory (INEL), United States in a programme of safety experiments. The initial proposal was developed from an initiative of the United States Department of Energy (US DOE), that also provided continuing management support. The project successfully combined the abilities and objectives of an international team with those of the reactor operation and analysis staff at INEL to provide a significant addition to both the international database of large-scale experimental data on reactor safety and to the analysis and understanding of the test results.

The experimental program of the LOFT Project comprised eight experiments, six thermal-hydraulic experiments and two fission product release experiments:

  • LP-FW-1 – Loss-of-feedwater, primary feed and bleed recovery procedure - (20/02/1983)
  • LP-SB-1 – Hot leg SB LOCA, early pump trip - (23/06/1983)
  • LP-SB-2 – Hot leg SB LOCA, delayed pump trip - (14/07/1983)
  • LP-SB-3 – Cold leg SB LOCA, core uncovery, secondary feed and bleed recovery procedure, accumulator injection at low-pressure differential - (05/03/1984)
  • LP-02-6 – 200% large-break LOCA, US licensing case - (03/10/1983)
  • LP-LB-1 – 200% large-break LOCA UK, licensing case - (03/02/1984)
  • LP-FP-1 – Gap fission product release, large-break LOCA, German licensing case - (19/12/1984)
  • LP-FI-2 – Fission product release at high fuel temperatures (above 2100 K), V-sequence - (03/07/1985)

In summary, the project achieved the following:

  • The managerial decisions and the detailed planning of the programme were successfully organised by the collective decisions of members. The lessons learnt from this aspect of the project should be of permanent value for future international initiatives.
  • The detailed experimental results provided valuable new evidence on thermal-hydraulic issues and an important international database for computer code verification.
  • It provided a valuable forum for the exchange of specialist views and for computer code comparisons.
  • The two tests, LP-FP-1 and LP-FP-2, extended the use of LOFT to provide data on fission product release and transport from failed fuel. LP-FP-2 was also a major data source on severe core damage phenomena in a large fuel bundle and work on the assessment of data from this test was expected to continue over a number of years.
  • Effective measures were taken to make the data of long-term value by archiving it with the NEA Data Bank, making the data available as part of the NEA Committee on the Safety of Nuclear Installations (CSNI) Code Validation Matrix and linking further work based on the LOFT data with international programs such as the CSNI specialist working groups, the International Code Assessment and Applications Program (ICAP) and the USNRC Severe Fuel Damage Program.
  • There was general agreement that there were problems in retaining facilities and expertise in a number of reactor safety area and that the facilities offered by LOFT were irreplaceable. The NEA LOFT programme successfully made use of LOFT but was not able to provide a route for its further retention.

A report was issued in 1990 and can be found below.

Project data

Project data and reports are available to NEA member countries organisations upon request at LOFT data packages.


Austria, Finland, Germany, Italy, Japan, Spain, Sweden, Switzerland, the United Kingdom and the United States.

Project period

January 1983-December 1989


~ USD 100 million