Neutronics Studies of the Gas-Carried Lithium Oxide Cooling-Breeding Fusion Reactor Blanket and Shield

The neutronics and photonics of the gas-carried Li₂O blanket have been studied. The blankets studied consist of 20 to 30% Li₂O solid particles and 2% Type 316 stainless-steel structural material in volume. The Li₂O blanket can achieve a high tritium breeding ratio without a neutron multiplier due to its high lithium atom density. The effects of the design variations on the tritium breeding ratio and total nuclear heating are summarized as follows:

1. The tritium breeding ratio is relatively insensitive to the graphite reflector thickness and, as found in the UWMAK-I design, is also insensitive to the ¹Li enrichment.
2. The total nuclear heating is ∼15 MeV per deuterium-tritium neutron. The contribution from gamma-ray heating is ∼20%.

The performance of the shield and the thermal behavior of the magnet in case of a loss-of-coolant accident (LOCA) are also investigated. The superconducting toroidal field coil will go normal ∼100 s after a LOCA occurs, which is about one order of magnitude longer than the time required to shut down the plasma. The radioactivity and afterheat after shutdown of the reactor have been calculated and found comparable to the stainless-steel-structured UWMAK-I design.