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Fusion Science and Technology
Latest News
Norway’s Halden reactor takes first step toward decommissioning
The government of Norway has granted the transfer of the Halden research reactor from the Institute for Energy Technology (IFE) to the state agency Norwegian Nuclear Decommissioning (NND). The 25-MWt Halden boiling water reactor operated from 1958 to 2018 and was used in the research of nuclear fuel, reactor internals, plant procedures and monitoring, and human factors.
G. Dell'Orco, M. Simoncini, D. Zito, G. Vella
Fusion Science and Technology | Volume 39 | Number 2 | March 2001 | Pages 644-648
Fusion Materials | doi.org/10.13182/FST01-A11963311
Articles are hosted by Taylor and Francis Online.
Both the EU Long Term Programmes for DEMO and the ITER R&D foresee the thermal-mechanical qualification of the beryllium, as neutron multiplier, and lithium orthosilicate or lithium metatitanate as breeder ceramics pebble beds. FZK has performed measurements on the pebble bed thermal-mechanical properties using cylindrical test sections. Using an alternative approach, ENEA, has launched similar testing on the SMARTS mock-up, reproducing on a small scale the reactor reference plane geometry1 instead. The tests have shown that the pebble bed thermal behaviour is strongly affected by the initial filling Packing Factor (PF). In fact, the higher the PF, the higher the thermal conductivity of the bed. Therefore, if the neutron multiplication needs an increase in the pebble PF, the only possibility is to adopt binary pebble beds (small pebbles infiltrating between larger ones) as an alternative to the mono-sized lattice. Using binary pebble beds, the filling quality should be guaranteed against the occurrence of de-mixing or swimming of the larger pebbles over the smaller ones during the thermal transients. A possible solution is to optimise the filling procedure, to improve the PF and its relevant thermal performance, and also to achieve a stable bed lattice during the cycling loads. In this case, the mechanical characteristics of the pebble beds would also be heavily affected, thus requiring a new tests campaign to determine the actual mechanical properties of an “optimised” pebble bed. This paper presents a new filling optimisation method and the experimental results from the compression tests of optimised pebble beds.