To help the development of deep-space probes in the United States, scientists at Oak Ridge National Laboratory (ORNL) have just made an important progress—through the improvement of the automated process of key steps, the use of the launch heat generator (RTG) To produce plutonium-238 (PU-238) nuclear fuel production efficiency. It is reported that ORNL scientists have delivered the production process of alumina-aluminum particles to the machine, and it is expected that by 2025, the output of nuclear fuel will be increased to 1.5 kg (3.3 lb) per year.
(Picture comes from: ORNL)
NASA hopes to send more unmanned probes to the outer solar system. At the same time, it will also launch nuclear-powered probes to Mars and arrange manned space flight outposts on the moon.
A current bottleneck is that the agency ’s PU-238 nuclear fuel reserves have been reduced to less than 35 kg (77 lb).
In order to increase inventory, ORNL must use the funds it has acquired to produce more nuclear fuel for deep space missions. After all, at such a distance from the sun, photovoltaic panels can no longer be expected.
It should be pointed out that PU-238 is an unstable plutonium isotope. When it naturally decays into uranium-234, it produces 0.5 watts of thermal energy.
A launching heat generator (RTG) can use this heat to generate electricity to power the spacecraft. Since the 1960s, the system has been working well, but the process of preparing PU-238 is somewhat laborious.
To produce plutonium isotopes, ORNL first converts ne-237 (NP-237) to oxidized ne, then mixes with aluminum and compacts into dense particles.
They were then passed through a laboratory's high-throughput isotope reactor, using radiation to convert NP-237 to NP-238 (which decays into PU-238).
Then plutonium is chemically treated to turn the purified plutonium into fuel pellets. It is embarrassing that it involves too many manual operations, which seriously slows down production efficiency.
Previously, ORNL could only produce 80 pellets per week. But on a brand new, partially automated production line, its output has increased to 275 pellets per week. BobWham stated:
This automation improvement involves only part of the Pu-238 production process, but it helps increase the annual output from 50 grams to 400 grams, which is close to NASA's goal of 1.5 kilograms by 2025.
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