8.4 Conclusion
To perform the design study for the transmutation system of long-lived nuclides,
the construction of TEF, which consists of two buildings, TEF-T and TEF-P, is
proposed under the J-PARC Project. According to the current construction schedule, TEF-T will be built at the first phase and TEF-P will be constructed at the latter
phase. Licensing procedures for TEF-P construction will be processed simultaneously with TEF-T construction.
TEF-T is a facility to prepare the database for engineering design of an ADS
using a 400 MeV–250 kW proton beam and the Pb-Bi spallation target. The
purposes of TEF-T are R&D for the structural strength of the beam window,
which is irradiated by both high-energy protons and neutrons, compatibility of
the structural material with flowing liquid Pb-Bi, and operation of the high-power
spallation target. Several kinds of target head can be installed according to the
experimental requirement. It was shown that the reference case of injected proton
beam condition (400 MeV–250 kW and 20 μA/cm
2 of beam current density) was
applicable to the TEF-T target. Further studies to improve irradiation performance
are under way.
TEF-P is a critical assembly, which can accept the 400 MeV–10 W proton beam
for the spallation neutron source. The purposes of TEF-P are the experimental
validation of the data and method to predict neutronics of the fast subcritical system
with spallation neutron source, demonstration of the controllability of a subcritical
system driven by an accelerator, and basic research of reactor physics for transmutation of MA and LLFP. The distinguishing points of the TEF-P in comparison with
existing experimental facilities can be summarized as follows: (1) both the highenergy proton beam and the nuclear fuel are available, (2) the maximum neutron
source intensity of about 10
12 n/s is strong enough to perform precise measurements
even in the deep subcritical state (e.g., k eff ¼ 0.90) and is low enough to easily
access the assembly after the irradiation, (3) a wide range of pulse width (1 ns–
0.5 ms) is available by the laser charge exchange technique, (4) MA and LLFP can
be used as a shape of foil, sample, and fuel by installing an appropriate shielding
and remote handling devices.
Along with the design study of the TEF, R&D for the components required for
TEF, such as the laser charge exchange technique to extract a very low power
proton beam, test manufacturing of MA fuel-handling devices, and operation of
lead-bismuth test loops are under way. From the experimental results of the laser
charge exchange technique, beam extraction in the magnetic field is successfully
demonstrated. Mockup of the coolant simulator block and remote handling mechanism for pin-type fuel loading has been done. An effective method to remove
polonium with a standard stainless mesh filter was established through the hot
experiments. Significant improvement of analysis accuracy of actual ADS was
expected by critical experiment with MA fuel at TEF-P.
When the target of TEF-T operates with a full power beam, a fast neutron
spectrum field is formed around the target and it is possible to apply multipurpose
78
T. Sasa
To perform the design study for the transmutation system of long-lived nuclides,
the construction of TEF, which consists of two buildings, TEF-T and TEF-P, is
proposed under the J-PARC Project. According to the current construction schedule, TEF-T will be built at the first phase and TEF-P will be constructed at the latter
phase. Licensing procedures for TEF-P construction will be processed simultaneously with TEF-T construction.
TEF-T is a facility to prepare the database for engineering design of an ADS
using a 400 MeV–250 kW proton beam and the Pb-Bi spallation target. The
purposes of TEF-T are R&D for the structural strength of the beam window,
which is irradiated by both high-energy protons and neutrons, compatibility of
the structural material with flowing liquid Pb-Bi, and operation of the high-power
spallation target. Several kinds of target head can be installed according to the
experimental requirement. It was shown that the reference case of injected proton
beam condition (400 MeV–250 kW and 20 μA/cm
2 of beam current density) was
applicable to the TEF-T target. Further studies to improve irradiation performance
are under way.
TEF-P is a critical assembly, which can accept the 400 MeV–10 W proton beam
for the spallation neutron source. The purposes of TEF-P are the experimental
validation of the data and method to predict neutronics of the fast subcritical system
with spallation neutron source, demonstration of the controllability of a subcritical
system driven by an accelerator, and basic research of reactor physics for transmutation of MA and LLFP. The distinguishing points of the TEF-P in comparison with
existing experimental facilities can be summarized as follows: (1) both the highenergy proton beam and the nuclear fuel are available, (2) the maximum neutron
source intensity of about 10
12 n/s is strong enough to perform precise measurements
even in the deep subcritical state (e.g., k eff ¼ 0.90) and is low enough to easily
access the assembly after the irradiation, (3) a wide range of pulse width (1 ns–
0.5 ms) is available by the laser charge exchange technique, (4) MA and LLFP can
be used as a shape of foil, sample, and fuel by installing an appropriate shielding
and remote handling devices.
Along with the design study of the TEF, R&D for the components required for
TEF, such as the laser charge exchange technique to extract a very low power
proton beam, test manufacturing of MA fuel-handling devices, and operation of
lead-bismuth test loops are under way. From the experimental results of the laser
charge exchange technique, beam extraction in the magnetic field is successfully
demonstrated. Mockup of the coolant simulator block and remote handling mechanism for pin-type fuel loading has been done. An effective method to remove
polonium with a standard stainless mesh filter was established through the hot
experiments. Significant improvement of analysis accuracy of actual ADS was
expected by critical experiment with MA fuel at TEF-P.
When the target of TEF-T operates with a full power beam, a fast neutron
spectrum field is formed around the target and it is possible to apply multipurpose
78
T. Sasa