A Functionally Graded Composite for Service in High-Temperature Lead- and Lead-Bismuth–Cooled Nuclear Reactors—I_ Design

Short and Ballinger
A COMPOSITE FOR HIGH-TEMPERATURE LEAD- AND LEAD-BISMUTH–COOLED REACTORS—I
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Fig. 14. Power and P0D ratio performance gains by increasing
the coolant flow velocity and outlet temperature. The
baseline design point of 2400 MW~thermal! is shown
as compared to power contours for the new design.
The P0D ratio gives an estimate of the size of the core.
This figure shows how increasing the outlet temperature
by using the composite in this study can lead to
the design of a smaller core at the same power level or
a higher-power core of the same size.
IV.B. Economic Gains
A number of factors made possible by this FGC contribute
to lowering the cost of a lead-cooled fast reactor
~LFR! plant:
1. Keeping the power level constant allows for shrinking
of the core due to a higher power density,
leading to less materials cost.
2. Conversely, keeping the core size constant would
allow for more electricity production out of the
same core.
3. Eliminating FAC reduces the risk of reactor material
degradation.
4. A smaller core and more passive safety systems
~due to higher permissible temperatures and power
densities! shrink the footprint of the plant, saving
materials and construction costs.
V. CONCLUSIONS
Based on this research, the following conclusions
may be stated:
1. The FGC developed in this research protects
against lead-bismuth corrosion in all expected environments,
both oxidizing and reducing, such that corrosion
Fig. 15. Increase in operating region based on reasonable design
constraints for a lead-bismuth-cooled reactor.
Pumping work, vessel size, pressure drop, heat exchangers,
and coolant flow velocity were considered
when restricting the recommended operation region.
will hopefully no longer be a concern for lead-bismuth–
cooled systems. Extrapolated corrosion rates based on
the experiments in this study are ,1 mm0yr, which is
negligible in terms of reactor design, even assuming a
60-yr reactor lifetime for structural components. It should
be noted that further corrosion studies are necessary to
confirm both long-term corrosion behavior and corrosion
resistance in flowing lead-bismuth.
2. The FGC is diffusionally stable. The diffusional
dilution zone between the two layers will not exceed
17 mm for fuel cladding ~3-yr life! or 33 mm for coolant
piping ~60-yr life!, both assumed to operate at 7008C.
3. Because of the performance gains above, the FGC
represents a potential enabling technology for leadbismuth–cooled
reactors and systems.Asteady-state temperature
increase of up to 1508C beyond the current
limitation of 5508C is possible, provided that suitable
structural materials exist. This allows reactor designers
to increase the power density and0or increase the output
of their reactors and to include larger safety margins in
case of an accident.
4. This FGC is ready for immediate deployment in
nonirradiated or low-dose applications. The corrosion
resistance has been demonstrated and will be verified
pending longer-length experiments. Further work is required
to investigate the properties of the FGC under
flowing lead-bismuth and irradiation, especially at temperatures
below 4508C where mechanical properties can
be adversely affected by fast neutron irradiation. 30
378 NUCLEAR TECHNOLOGY VOL. 177 MAR. 2012