Power ramp experiments in the nuclear power plant Biblis-A

Two ramp experiments have been performed in the Biblis-A reactor on two-cycle standard fuel assemblies. The power range of these experiments covered the conditions representative for extreme transient operation of large PWRs. In order to perform such ramp tests in power reactors, a modified control rod inserted into the assembly for its second operational cycle was rapidly withdrawn. Furthermore, ramp powers of up to 410 W/cm have been achieved only by special reactor operation deviating from standard operation. The fuel rods with burnups of up to 30,600 MWd/t(M) showed a very good ramping behaviour. No fuel defects have occurred. This has been demonstrated on a statistically significant number of fuel rods. (author)