ThorEA - Towards an Alternative Nuclear Future.pdf

Appendix III:
International research on thorium fuels and fuel cycles
Since the early 1960s, extensive studies on the thorium fuel cycle and its deployment have been conducted in Germany, India,
Japan, the Russian Federation, the United Kingdom, and the USA. These included studies in material data, fabrication tests,
irradiation of Thorium-based fuel in material test reactors with post-irradiation examinations, and investigations into the use
of thorium based fuel for Light Water, Liquid Metal Fast Breeder, and High Temperature Gas Reactors. Test reactor irradiations
of thorium fuel to significant burn-ups (up to 150 GWd/t) at high specific heat loads (up to 680 W/cm) have also conducted.
Additionally, several test reactors have been either partially or completely loaded with Thorium-based fuel.
A.3.1 Experimental reactors
Dragon reactor, United Kingdom:
In this 20 MWth HTGC reactor, which started operation
in 1966, thorium fuel elements (10:1 Th:HEU ratio) were
irradiated for 741 full power days.
MSRE ORNL, USA:
The Molten Salt Reactor Experiment (MSRE) at Oak Ridge
National Laboratory (ORNL) was a 7.4 MWth graphitemoderated
reactor operated from 1960 for 5 years. The molten
salt was LiF-BeF2-ZrF4-UF and the fuels were Pu-239, U-235
and U-233. The operation successfully completed its objectives,
including the study on U-233 operation at high power.
Peach Bottom HTGR, USA:
The Peach Bottom reactor was a high-temperature, graphitemoderated,
helium-cooled reactor experiment operating at
110 MWth with HEU/Th coated-particle fuel, from 1966 to 1972.
Power Reactors
Considerable experience has been gained in thorium based fuel
in power reactors worldwide. The following reactors have either
irradiated thorium fuel or are preparing test irradiations:
THTR, Germany:
300 MWe reactor operated with 675,000 pebbles containing
Th-HEU fuel from 1985 to 1989. Fuel fabrication was on an
industrial scale.
Fort. St. Vrain, USA:
The Fort St. Vrain reactor was a HTGR (graphite moderated,
helium-cooled) reactor with thorium and HEU fuel designed to
operate at 842 MWth (330 MWe). The fuel was in microspheres
of thorium carbide and Th/U-235 carbide. Almost 25 metric
tons of thorium fuel was manufactured for this reactor.
Excellent results in matching reactor physics calculations
(e.g. temperature coefficients, control rod worth, reactivity
evolution as a function of burn-up) with measurements(^ref).
Indian Point & Shippingport, USA:
Thorium based fuel for PWRs was investigated at the Indian
Point reactor (285 MWe) using both U-235 and plutonium as
the initial fissile material and it was concluded that it would
not significantly affect operating strategies or core margins
(^ref). A Thorium-based plutonium-burner was proposed for
the LWR fuel cycle. The LWBR concept was also tested in the
Shippingport reactor (100 MWe, largest breeder in the World)
using thorium and U-233 fuel in zircaloy clad. The core was
operated from 1977 for 5 years without fuel failure, achieving a
maximum burn-up of 60 GWd/t and successfully demonstrated
breeding of U-233 using the seed/blanket concept.
52 Towards an Alternative Nuclear Future
BWR, Lingen, Germany:
Th/Pu-based fuel test elements were used in this
60 MWe reactor.
A3.2 The Special Case of India: Thorium-Fuel
Reactors and Experiments
There has been sustained interest in India for the thorium fuels
and fuel cycles due to its large deposits of thorium (518,000
tonnes; mostly as monazite in beach sands), compared to its
limited mineral Uranium reserves (92,000 tonnes). The longterm
sustainability of India’s civil nuclear energy programme
greatly depends on the large-scale utilization of its vast
thorium resources for breeding and recycling fissile U-233 in
a self-sustaining Th-232/U-233 closed fuel cycle.
Therefore, the case of India is of particular interest given
its current leadership in thorium research programs. Since
its inception, India’s nuclear power program, contemplated
three phases, namely i) the use of heavy water reactors; ii)
the development of fast breeders; and iii) the development
of thorium based reactors to utilise its vast reserves.
Intense work on the thorium cycle began in the 80s when this
cycle was analyzed for all possible reactor configurations. MSRs
were proposed as theoretically optimal for this cycle although
PHWRs appeared as the natural option to develop this fuel cycle,
given the well-proven technology and availability. Several power
reactors are currently in operation in this country:
CIRUS, KAMINI and DHRUVA Reactors, India:
CIRUS is a 40 MWth PHWR in BARC, near Mumbai, where fuel
fabrication, irradiation and examination of spent Th-fuel (up
to 18 GWd/t burn-up) has been carried out.
Reaching criticality in 1996, KAMINI is a 30 kWth light water
experimental reactor, specifically designed to use metallic
uranium-233 as fuel.
Largest research reactor in India, DHRUVA is a 100 MWth
PHWR similar to CIRUS, also based in BARC. Work to optimise
and confirm the physics design parameters of the AHWR using
(Th-Pu)O2 and (Th-U-233)O2 fuels has been carried out.
KAPS Units 1 and 2, KAIGA Units 1 and 2, and RAPS 3
and 4, India:
All units are 220 MWe PHWRs. Each KAPS unit is loaded with
500kg Th-fuel; in June 1995, Unit 1 had achieved about 300 days
of full power operation, Unit 2 about 100 days. More units in the
KAIGA and RAPS power stations are under construction. The use
of Th-based fuel is planned for power flattening. Work on postirradiation
examinations, reprocessing (laboratory scale and
pilot-scale) and re-fabrication (laboratory scale) continues and
has been enlarged based on these experiments.