Mostly that it still generates radwaste. No way to avoid that with heavy-element fission.
That’s why NASA is looking at it. Radwaste isn’t a human contamination problem in space.
https://www.fulviofrisone.com/attachments/article/469/VOL%2029..pdf
pages 105-118
Space Application of the GeNIE HybridTM
Fusion–Fission Generator
Lawrence P. Forsley∗
and Pamela A. Mosier-Boss
Global Energy Corporation, San Diego, CA 92123, USA
∗Corresponding author. E-mail: lawrence.p.forsley@nasa.gov.
⃝c 2019 ISCMNS. All rights reserved. ISSN 2227-3123
96 L.P. Forsley and P.A. Mosier-Boss / Journal of Condensed Matter Nuclear Science 29 (2019) pages 105–118
Abstract
JWK Corporation and Global Energy Corporation (GEC) have spent the past two decades understanding and applying nuclear reactions in condensed matter with the US Navy and NASA. The Navy cooperation resulted in US Patent, 8,419,919, System and Method for Generating Particles.
The use of this patent to fission uranium is described in a companion paper, Uranium Fission
Using Pd/D Co-deposition.
GEC is applying this technology as a non-fissile reactor core suitable for deep-space power under its second NASA Space Act Agreement. This paper discusses the need for space-based nuclear power, the alternatives, the hybrid fusion-fast-reactor and the spaceflight readiness testing facilities.
⃝
Keywords: Fast fission, Fusion, LANR, NASA, Space power
1. Overview
NASA has used solar power for 50 years and nuclear power beginning three years later. Solar powered spacecraft are generally limited to the inner Solar System out to Mars, with the exception of the 60 foot solar panel span of the JUNO
Jupiter orbiter. Other than the US SNAP-10 fission reactor, each of nearly 40 missions, including New Horizons to
Pluto, were powered by plutonium (238Pu) radioactive thermoelectric generators (RTG). Although run for decades as
seen with the now 41 years extended missions of the two Voyager spacecraft, RTGs provide less than 1 kW of electrical
power (kWe). Meanwhile the Soviets flew 31 fission reactors in low-earth orbit (LEO) each producing up to 10 kWe.
Unfortunately, the Kosmos-954 satellite came down over Northern Canada in 1978 and contaminated 124,000 km2 of
territory. Hence, there’s reluctance to fly fissile material and non-fissile RTGs as used on the Jupiter Galileo, Saturn
Cassini, Pluto New Horizons and Mars Curiosity spacecraft as well as the earlier Voyager and Pioneer Missions
More on the hybrid fusion/fission reactor...
5.1. Hybrid reactor
GEC is developing a space-rated, hybrid, fusion-fast-fission, thorium reactor. This has different, and in some ways
more stringent, requirements than a terrestrial reactor. For example, it needs a mean-time-to failure exceeding 50,000 h
(5.7 years), to enable most missions of interest, as repair is usually impossible [21]. Initially, it will be mated to the
NASA Glenn Advanced Stirling Engine that is used with the KRUSTY reactor. This sets specific mass, volume and
temperature requirements.
Like KRUSTY, the goal has been to move in steps from tens of watts to tens of kilowatts. The first Kilopower
Program demonstration, DUFF, produced 24 We using a Stirling Engine with a heat pipe. These Stirling engines have
a conversion efficiency of 10–30% thermal to electric depending upon the temperature difference, ∆T, between the
operating temperature and the heat dump. Despite space being cold it is also a well-insulating vacuum.
The Hybrid Reactor upper temperature limit is controlled by materials. But, this has an upside. For example, the
hydrided enriched uranium metal fuel rods used in General Atomic TRIGA thermal fission reactors are self-moderating
with a rapid, negative temperature co-efficient. TRIGA reactors are considered inherently safe.
5.2. 238U and 232Th fission cross-sections
The following figures show the neutron [22] and proton [23] actinide fission cross-sections in barns (1 b=10−24 cm2
)
and incident particle kinetic energy in meV (10−3
eV) to MeV (106
eV) units. Colored arrows indicate neutron
and proton kinetic energies observed in condensed matter reactions estimating scattering losses through both the co-deposition layer and electrolyte between the active surface and the CR-39. Note that both the log energy and crosssection scales vary by figure. Neutral neutron interactions have a higher cross-section than charged protons due to the
lack of a Coulomb Barrier. But, fast protons will fission actinides. What is not shown are competing reactions like
capture and spallation reactions (n,n′
), (n,2n), (n,p), (p,n), etc. These reactions create excited nuclei that do not directly
fission.
Sustained thermal neutron fission requires >3%b of odd-numbered actinides, like 233U, 235U, and 239Pu that have
high thermal neutron (0.025 eV) fission cross-sections, σt, of 500–600 b. Most fission reactors use water or graphite
to moderate, or thermalize and slow, the 1+ MeV fission neutrons to thermal energy. A fast fission reactor uses
unmoderated neutrons but requires nearly 20% enrichment of the odd-numbered, fissile nuclei since the fast neutron
fission cross-section, σf drops to ≈1 b. Fast and thermal reactors can convert, or breed, even numbered (fertile) nuclei
into odd-numbered (fissile) nuclei by neutron capture. Both reactors depend upon a neutron chain reaction producing
>2 neutrons/fission. Reactor criticality is maintained by a neutron economy controlling how many neutrons escape
(geometry) are captured (fission poisons, control rods and breeding fissile fuel) or are delayed (fission product neutron
decay).
5.3. Fusion fast fission reactions
By comparison, our Hybrid reactor is sub-critical relying upon neither fissile fuel nor a fissile chain reaction. It is a fast
reactor, fissioning both fissile and fertile nuclei. The fusion-fast-fission reactor is based upon previous work described
in “Investigation of Nano-nuclear Reactions in Condensed Matter: Final Report” [24] and discussed in, “Uranium
Fission Using Pd/D Co-deposition” [25]. As noted, fast neutron energies of 6.3–6.83 MeV have been measured with
average fluxes exceeding 106 n/s. The instantaneous flux exceeded this rate.
Figure 10 shows the DT Fusion-Fast-Fission reaction. DD fusion-fast-fission is similar. Both primary and secondary fusion and induced fast fission reactions were generated using the patented protocol [24].
Combining the most probable primary and secondary fusion reactions result in ≈8 MeV kinetic energy in fast
proton, helium and alpha particles with ≈16 MeV as neutron kinetic energy. By comparison, actinide fission produces
≈170 MeV in charged fission fragments and ≈30 MeV in gamma and neutron kinetic energies with ≈ 3 × 1010
fissions/watt-thermal Although the fusion neutron energy drives the fission reactions the overriding thermal power is
from fission products.
The NASA version of the Hybrid fusion-fast-fission reactor will be tested in a series of stages analyzing neutron
flux, stability and pressurized gain with high temperature aqueous operation at <150◦C and <4 bar pressure. Low
energy X-ray, γ and visible light diagnostics require a 250 ml glass pressure vessel (Fig. 12). Higher temperatures,
pressures and volumes require Hastelloy and stainless steel vessels. The reactor is housed in a calorimeter (Fig. 11) that
was recently calibrated to 200 mW or better sensitivity with an ≈ 40 W upper limit. All of the materials, containment
vessels and previous operating procedures have been subject to NASA GRC and Plum Brook Health Physics and
Safety reviews as will modified experiment protocols.