by
Hamid Aït Abderrahim(Belgian Nuclear Research Centre)
→
Europe/Stockholm
12167 (Ångström)
12167
Ångström
Description
Presently, the European Union produces 30% of its electricity by Gen.II and III nuclear reactors. This leads to the production of 2500 t/y of used fuel, containing 25 t of Plutonium, and High Level Wastes (HLW) such as 3.5 t of minor actinides (MA), namely Neptunium (Np), Americium (Am) and Curium (Cm) and 3 t of long-lived fission products (LLFPs). The used fuel reprocessing followed by the geological disposal or the direct geological disposal are today the envisaged solutions depending on national fuel cycle options and waste management policies. The Partitioning and Transmutation (P&T) has been pointed out in numerous studies as the strategy that can relax constraints on the geological disposal, and reduce the monitoring period to technological and manageable time scales. Transmutation based on critical or sub-critical fast spectrum transmuters should be evaluated, in order to assess the technical and economic feasibility of this waste management option.
From 2005, the research community on P&T within the EU started structuring its research towards a more integrated approach. This resulted during the FP6 into two large integrated projects namely EUROPART dealing with partitioning and EUROTRANS dealing with ADS design for transmutation, development of advanced fuel for transmutation, R&D activities related to the heavy liquid metal technology, innovative structural materials and nuclear data measurement. This approach resulted in a European strategy given in introduction based on the so-called “four building blocks” at engineering level for P&T.
The MYRRHA project contributes heavily to the third building block of this European strategy and in this paper we will focus on the ADS programme in the EU through the MYRRHA project. The MYRRHA project, proposed by SCK•CEN, aims to demonstrate the feasibility and operability of a safe and efficient transmuter, composed of a subcritical reactor fed by an external neutron source, in turn obtained by a proton accelerator. The most significant characteristics of the required beam are:
Beam energy = 600 MeV
Beam current = 4 mA
Time structure = CW, with 200 µsholes at 250 Hz
Beam stability = Energy ±1%; Current ±2%, Position and size ±10%
MTBF >250 h (failure being a beam trip longer than 3 s)
These specifications set the MYRRHA accelerator in the category of HPPA.While the specificity and difficulty of the Continuous Wave (CW) nature of the beam delivery of MYRRHA is acknowledged, the outstanding design feature is the the requirement of 250 hours as Mean Time Between Failures (MTBF), corresponding to less than 10 failures (i.e. a beam trip longer than 3 s) over a 3 month operation cycle. The allowed beam trip frequency of the whole accelerator is significantly lower than
observed on today's reported achievements of comparable accelerators, therefore the issue of reliability is considered the main design challege, and concerns all the R&D activities.
In this seminar we will present the EU strategy for P&T and the status of the MYRRHA project as by End-2015 concerning the technical design of the reactor and in particular of the accelerator, the pre-licensing and the projected implementation scenario for the realisation of the MYRRHA facility.
