various irradiation positions, representative irradiation temperature, and representative neutron spectrum conditions; the main target will be fastspectrum GEN IV systems;
– Material developments for fusion reactors, which need also large irradiation
volumes with high constant fast flux level (Φ >1 MeV ¼ 1 ~ 5 · 10
14 n/cm
2 s), a
representative irradiation temperature, and a representative ratio appm
He/dpa(Fe) ¼ 10;
– Radioisotope production for medical and industrial applications by
• Holding a backup role for classical medical radioisotopes;
• Focusing on R&D and production of radioisotopes requiring very high
thermal flux levels (Φ thermal ¼ 2 to 3 · 10
15 n/cm
2 s) because of doublecapture reactions;
– Industrial applications, such as Si-doping, need a thermal flux level
depending on the desired irradiation time: for a flux level Φ thermal ¼ 10
13 n/
cm
2 s, an irradiation time in the order of days is needed, and for a flux level of
Φ thermal ¼ 10
14 n/cm
2 s, an irradiation time in the order of hours is needed to
obtain the required specifications.
Further in this section, we discuss some basic characteristics of the accelerator and
of the core and primary system design.
7.3 The MYRRHA Accelerator
The accelerator is the driver of MYRRHA because it provides the high-energy
protons that are used in the spallation target to create neutrons, which in turn feed
the core. In the current design of MYRRHA, the machine must be able to provide a
proton beam with energy of 600 MeV and an average beam current of 3.2 mA. The
beam is delivered to the core in continuous wave (CW) mode. Once per second, the
beam is shut off for 200 μs so that accurate on-line measurements and monitoring of
the subcriticality of the reactor can take place. The beam is delivered to the core
from above through a beam window.
Accelerator availability is a crucial issue for the operation of the ADS. A high
availability is expressed by a long mean time between failure (MTBF), which is
commonly obtained by a combination of overdesign and redundancy. In addition to
these two strategies, fault tolerance must be implemented to obtain the required
MTBF. Fault tolerance will allow the accelerator to recover the beam within a beam
trip duration tolerance after failure of a single component. In the MYRRHA case,
the beam trip duration tolerance is 3 s. Within an operational period of MYRRHA,
the number of allowed beam trips exceeding 3 s must remain under 10. Shorter
beam trips are allowed without limitations. The combination of redundancy and
fault tolerance should allow obtaining a MTBF value in excess of 250 h.
7 Contribution of the European Commission to a European Strategy for HLW. . .
63
– Material developments for fusion reactors, which need also large irradiation
volumes with high constant fast flux level (Φ >1 MeV ¼ 1 ~ 5 · 10
14 n/cm
2 s), a
representative irradiation temperature, and a representative ratio appm
He/dpa(Fe) ¼ 10;
– Radioisotope production for medical and industrial applications by
• Holding a backup role for classical medical radioisotopes;
• Focusing on R&D and production of radioisotopes requiring very high
thermal flux levels (Φ thermal ¼ 2 to 3 · 10
15 n/cm
2 s) because of doublecapture reactions;
– Industrial applications, such as Si-doping, need a thermal flux level
depending on the desired irradiation time: for a flux level Φ thermal ¼ 10
13 n/
cm
2 s, an irradiation time in the order of days is needed, and for a flux level of
Φ thermal ¼ 10
14 n/cm
2 s, an irradiation time in the order of hours is needed to
obtain the required specifications.
Further in this section, we discuss some basic characteristics of the accelerator and
of the core and primary system design.
7.3 The MYRRHA Accelerator
The accelerator is the driver of MYRRHA because it provides the high-energy
protons that are used in the spallation target to create neutrons, which in turn feed
the core. In the current design of MYRRHA, the machine must be able to provide a
proton beam with energy of 600 MeV and an average beam current of 3.2 mA. The
beam is delivered to the core in continuous wave (CW) mode. Once per second, the
beam is shut off for 200 μs so that accurate on-line measurements and monitoring of
the subcriticality of the reactor can take place. The beam is delivered to the core
from above through a beam window.
Accelerator availability is a crucial issue for the operation of the ADS. A high
availability is expressed by a long mean time between failure (MTBF), which is
commonly obtained by a combination of overdesign and redundancy. In addition to
these two strategies, fault tolerance must be implemented to obtain the required
MTBF. Fault tolerance will allow the accelerator to recover the beam within a beam
trip duration tolerance after failure of a single component. In the MYRRHA case,
the beam trip duration tolerance is 3 s. Within an operational period of MYRRHA,
the number of allowed beam trips exceeding 3 s must remain under 10. Shorter
beam trips are allowed without limitations. The combination of redundancy and
fault tolerance should allow obtaining a MTBF value in excess of 250 h.
7 Contribution of the European Commission to a European Strategy for HLW. . .
63