Working Group on Fuel Safety (WGFS)

Programme of work

The working group's objective is to advance the current understanding of fuel safety margins and to address related safety issues. In particular, the working group aims to systematically assess the technical basis for current safety criteria and their applicability to the high burn-up and new fuel designs and materials being introduced. The needs and priorities for future research programmes in the area of fuel safety behaviour will also be examined, with the aim of understanding and adequately modelling key phenomena and quantifying safety margins.

Work in progress or recently finished

RIA Workshop

The Workshop on “Nuclear Fuel Behaviour during Reactivity Initiated Accidents” was held in Paris, France, on September 9-11 2009. The workshop was organised jointly by the “Committee for the Safety of Nuclear Installations” of the OECD and the French “Institut de Radioprotection et de Sûreté Nucléaire”.

More than 90 specialists representing 19 countries and international organizations attended the workshop. A total of 25 papers were presented. A workshop proceedings was published.

In connection with RIA Workshop results two new activities have been proposed and approved by CSNI on RIA fuel rod codes benchmark and Mechanical testing of fuel cladding for RIA applications.

LOCA criteria basis and test methodology

The ductility-based criteria derived from ring compression tests of double-side oxidized specimens, and rupture-based criteria derived from integral rod testing do result in quite different burn-up effect on the derived safety limit. The main objective of these WGFS activity was to review the LOCA criteria basis and the different test methodologies used to derive the criteria in the NEA member countries.

Fuel Safety Criteria - update

The scope of this activity is to produce an updated report on the current status of light water reactor fuel safety criteria used in NEA member countries (NEA/CSNI/R(99)25).

RIA fuel rod codes benchmark

The scope of activity is to organize a benchmark of RIA fuel rod codes based on a set of consistent, recent experiments performed in the NSRR and CABRI test reactors. In order to maximize the benefits from this exercise, it is foreseen to use a consistent set of 4 experiments on very similar highly irradiated fuel rods tested under different experimental conditions:

  • low temperature, low pressure, stagnant water coolant, very short power pulse,
  • high temperature, medium pressure, stagnant water coolant, very short power pulse,
  • high temperature, low pressure, flowing sodium coolant, larger power pulse,
  • high temperature, high pressure, flowing water coolant, medium width power pulse.

Mechanical testing of fuel cladding for RIA applications

Objectives of the task are to review the test methodologies in use in NEA member countries for characterising the fuel cladding mechanical response under reactivity initiated accident (RIA) and to provide recommendations how these methodologies can be used with respect to the parameters to be characterized. As a result of this task a Technical Opinion Paper has been drafted.

Future activities

Planned activities for the WGFS include:

  • reviewing design-basis accidents, especially loss-of-coolant accidents and reactivity-initiated accidents;
  • periodically assessing and reviewing fuel safety criteria;
  • investigating advanced fuel designs and the possible effect of such designs on safety margins (both for existing and advanced reactor designs).

Related links

WGFS overview

WGFS mandate

WGFS recent reports

Committee on the Safety of Nuclear Installations (CSNI) overview

E-mail contact: Radomir Rehacek ( )

Last reviewed: 14 February 2011