Last update in January 2011
Launched in 2000, the objective of the Cabri International Programme (CIP) is to study the behaviour of nuclear fuel pencils and their cladding during a reactivity injection accident (RIA) in pressurised water reactors (PWR). Such an accident would result in a rapid, sudden and local increase in the neutron flux, which would induce an increase in nuclear power due to fission.
The CIP programme comprises twelve tests in total. Placed under the aegis of OECD/NEA, this programme, coordinated and co-funded by IRSN, associates multiple French and international partners from twelve different countries.
The first two reactivity injection tests on irradiated pencils were carried out in the Cabri research reactor equipped with a “sodium loop”, in other words in which the coolant is liquid sodium. This loop represents the primary circuit in which the reactor coolant circulates. These two tests made it possible to study phenomena that do not depend on the nature of this coolant. However, to study conditions representative of an accident in a PWR, the “sodium loop” had to be replaced by a pressurised water loop. The renovation of the reactor core cooling circuit, as well as upgrading work vis-à-vis regulations, are underway.
The experimental programme consists in exposing sections of irradiated fuel under the thermohydraulic and neutronic power conditions encountered during a reactivity injection accident. Power transients are simulated by depressurisation of helium-3 (neutron absorbing gas) within the Cabri reactor core, at the centre of which the pencil to be tested is positioned.
- Initial reactor power: 0 to 10 MW
- Power transient duration: 10 to 100 ms
- Maximum transient power of the order of 20 GW
- Injected energy: up to 200 MJ
- Water loop characteristics: 280°C, 155 bars, flow rate up to 6 m3/h