The Studsvik SUPER-RAMP Project investigated the failure propensity of typical LWR fuel in the form of test rods when subjected to power ramps, after base irradiation to high burn-up.
The Project power ramped 28 individual PWR rods and 16 BWR rods. The PWR rods were all tested using high ramp rates. Due to different objectives for the BWR subprogramme, one set of the BWR rods was tested using a high ramp rate, and another set were tested with a very slow ramp rate.
All rods underwent a thorough examination programme, comprising characterisation prior to base irradiation, examination between base and ramp irradiation and examination after ramp irradiation.
The PWR Subprogramme consisted of 6 groups of rods with variations in design and material parameters. The rods were base irradiated in a power reactor environment KK Obrigheim or BR-3 at time averaged heat ratings mainly in the range 14-26 kW/m to peak burn-ups in the range 33-45 MWd/kgU and were subsequently ramp tested in the research reactor R2 at Studsvik, Sweden.
The BWR Subprogramme consisted of 3 groups of rods with variations in design and material parameters. The rods were based irradiated in BWRs Wurgassen, or Monticello at tie average heat ratings in the range 11 to 23 kW/m to peak burn-ups in the range 28 to 38 MWd/kgU and were subsequently ramp tested in the R2 reactor at Studsvik.
For both subprogrammes the following cover the principal activities:
- Design, fabrication and characterization of experimental fuel rods featuring certain design parameter characteristics. This part of the programme was performed prior to the start of the Project by the test fuel suppliers.
- Base irradiations of such experimental fuel rods in power reactors. This part of the Project was in place at the start of the Project.
- Pre-ramp examinations of the base-irradiated test fuel rods.
- Power ramp irradiations and ensuing non-destructive examinations of the test fuel rods in the est reactor R2 at Studsvik.
- Post-ramp examinations of the test fuel rods in hot cells.
- Data processing, reporting of test results and compilation of observations by the organization performing the work for each segment of the work scope.