Abstract
The High Average Power Laser (HAPL) power plant has targets that are directly driven by forty KrF laser beams. The final optics system includes a grazing incidence metallic mirror (GIMM) located at 24 m from the target. Several options were considered for the substrate material. We performed three-dimensional (3-D) neutronics calculations to assess the impact of the GIMM design options on the nuclear environment at the dielectric focusing and turning mirrors. We used the recently developed MCNPX-CGM Monte Carlo code that allows performing the neutronics calculations directly in the exact CAD model. Neutron traps are used behind the mirrors to reduce radiation streaming. The results indicate that material choice, density, and thickness for the GIMM impact the nuclear environment at all mirrors. The neutron flux and nuclear heating at the dielectric mirrors are a factor of ∼1.6 higher when AlBeMet is used instead of SiC as substrate in the GIMM. The fast neutron flux decreases by about three orders of magnitude as one moves from the GIMM to the focusing mirror with an additional two orders of magnitude attenuation at the turning mirror accompanied with significant spectrum softening.
Original language | English |
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Pages (from-to) | 1879-1883 |
Number of pages | 5 |
Journal | Fusion Engineering and Design |
Volume | 83 |
Issue number | 10-12 |
DOIs | |
State | Published - Dec 2008 |
Externally published | Yes |
Funding
This work has been performed through grants from the Naval Research Laboratory as part of the US Department of Energy funded HAPL program.
Keywords
- 3-D modeling
- Dielectric mirrors
- Metallic mirrors
- Radiation damage
- Radiation streaming
- Shielding