Within the European nuclear research community, a Technology Platform
named SNETP (Sustainable Nuclear Energy Technology Platform: www.snetp.
eu) gathers most of the stakeholders involved in reactor research. SNETP issued
a “Strategic Research Agenda” in May 2009 (revised in 2013 following the
Fukushima accident) with an Annex (in January 2011) devoted to Th. In the
annex, Th systems are noted as having significant long-term potentialities but
also significant challenges before reaching industrial implementation. The two
aspects (Pu management, molten salts) mentioned in this chapter were specifically
recognized in the Th Annex to the Strategic Research Agenda.
18.3 Th-MOX Fuels Irradiated in LWR Conditions
Within the European Framework Programmes, the study of Th fuels behavior in
LWRs was first aimed at comparing the behavior and the applicability of various
matrices to be used for the transmutation of Pu and minor actinides (projects
THORIUM CYCLE, LWR-DEPUTY, OMICO). Comparisons were made with
standard fuels (UO 2 , MOX), and also with so-called inert matrices fuels (using,
for example, Mo or MgO as matrix in CERMET and CERCER fuel types, respectively). As explained earlier, irradiation experiments were performed in three
facilities, namely, the KWO PWR, HFR, and BR2 Material Test Reactors.
The THORIUM CYCLE project was a 4-year project with the following participants: the coordinator NRG (NL), BNFL (UK), CEA (F), FZK and KWO (D), and
JRC-IE and JRC-ITU (EU). The goals of this project, which started on 1 October
2000, were to supply key data for application of the Th cycle in LWRs. In
particular, it included the study of
• The behavior of Th-based fuel at extended burn-up through an irradiation
experiment of four short fuel pins [UO 2 , (U,Pu)O 2 , ThO 2 , and (Th,Pu)O 2 ] up
to 55 GWd/tHM in HFR, and an irradiation experiment of one short fuel pin
[(Th,Pu)O 2 ] to 38 GWd/tHM in a PWR (KWO); it should be noted that a
previous irradiation of (Th,Pu)O 2 in Germany (Lingen) achieved a burn-up of
20 GWd/tHM [7];
• The core calculations for Th-based fuel, including code-to-code validation,
sensitivity check for significant isotopes
232 Th and
233 U, and the calculation
up to 80–100 GWd/tHM for Th-MOX fuel.
The irradiation test in KWO enabled the investigation of the operational safety
of Th-MOX rod behavior under realistic pressurized water reactor (PWR) conditions. The short test rod was inserted in a MOX assembly to provide the most
realistic boundary conditions possible. The foreseen MOX carrier assembly had
already been irradiated for one cycle. The cladding appeared in good condition after
irradiation, and its creep-down, measured at the reactor site during the shut-down
periods, as well as its general behavior, were well within the bounds of experience
for UO 2 fuels. The fission gas (Xe and Kr) release was about 0.5 % [8], which is
200
D. Haas et al.
named SNETP (Sustainable Nuclear Energy Technology Platform: www.snetp.
eu) gathers most of the stakeholders involved in reactor research. SNETP issued
a “Strategic Research Agenda” in May 2009 (revised in 2013 following the
Fukushima accident) with an Annex (in January 2011) devoted to Th. In the
annex, Th systems are noted as having significant long-term potentialities but
also significant challenges before reaching industrial implementation. The two
aspects (Pu management, molten salts) mentioned in this chapter were specifically
recognized in the Th Annex to the Strategic Research Agenda.
18.3 Th-MOX Fuels Irradiated in LWR Conditions
Within the European Framework Programmes, the study of Th fuels behavior in
LWRs was first aimed at comparing the behavior and the applicability of various
matrices to be used for the transmutation of Pu and minor actinides (projects
THORIUM CYCLE, LWR-DEPUTY, OMICO). Comparisons were made with
standard fuels (UO 2 , MOX), and also with so-called inert matrices fuels (using,
for example, Mo or MgO as matrix in CERMET and CERCER fuel types, respectively). As explained earlier, irradiation experiments were performed in three
facilities, namely, the KWO PWR, HFR, and BR2 Material Test Reactors.
The THORIUM CYCLE project was a 4-year project with the following participants: the coordinator NRG (NL), BNFL (UK), CEA (F), FZK and KWO (D), and
JRC-IE and JRC-ITU (EU). The goals of this project, which started on 1 October
2000, were to supply key data for application of the Th cycle in LWRs. In
particular, it included the study of
• The behavior of Th-based fuel at extended burn-up through an irradiation
experiment of four short fuel pins [UO 2 , (U,Pu)O 2 , ThO 2 , and (Th,Pu)O 2 ] up
to 55 GWd/tHM in HFR, and an irradiation experiment of one short fuel pin
[(Th,Pu)O 2 ] to 38 GWd/tHM in a PWR (KWO); it should be noted that a
previous irradiation of (Th,Pu)O 2 in Germany (Lingen) achieved a burn-up of
20 GWd/tHM [7];
• The core calculations for Th-based fuel, including code-to-code validation,
sensitivity check for significant isotopes
232 Th and
233 U, and the calculation
up to 80–100 GWd/tHM for Th-MOX fuel.
The irradiation test in KWO enabled the investigation of the operational safety
of Th-MOX rod behavior under realistic pressurized water reactor (PWR) conditions. The short test rod was inserted in a MOX assembly to provide the most
realistic boundary conditions possible. The foreseen MOX carrier assembly had
already been irradiated for one cycle. The cladding appeared in good condition after
irradiation, and its creep-down, measured at the reactor site during the shut-down
periods, as well as its general behavior, were well within the bounds of experience
for UO 2 fuels. The fission gas (Xe and Kr) release was about 0.5 % [8], which is
200
D. Haas et al.