Plutonium-238 would be helpful for future deep space missions: ORNL

Plutonium-238 would be helpful for future deep space missions: ORNL

Researchers at Oak Ridge National Laboratory (ORNL) have successfully produced Plutonium-238, the isotope which American space agency NASA was running out to fuel its Mars rovers. The success of project to create Plutonium-238 is considered as a major milestone by chemists and space technology experts. ORNL team has produced 50 grams of plutonium-238 and it will be helpful in future deep space missions.

As it decays, Plutonium-238 produces heat and can be used as power source for various space program instruments. The newly created Plutonium-238 will undergo analysis for testing its chemical purity. The production process will be scaled up after a team of researchers validates its efficiency.

The Department of Energy (DOE) said that it is for the first time that scientists have produced any Pu-238 since its Savannah River Plant is South Carolina ceased production in the late 1980s.

The ORNL has been working on this project since past few years using the finding provided by NASA via the Department of Energy's Office of Nuclear Energy.

A report published in Christian Science Monitor said, “Fifty grams isn't much, but this is the first time the substance has been made in the country since the Savannah River Plant in South Carolina stopped making it in the late 1980s. Right now, NASA only has access to 35 kilograms, about 77 pounds, of Pu-238 to power space exploration missions. That's just enough to last into the middle 2020s, powering just two or three proposed missions.”

The laboratory for their experiments used the High Flux Isotope Reactor for production of the plutonium isotope and then processed and purified the radioactive material in a series of shielded hot cells.

As per experts, the Pu-238 is majorly used in space power systems known as radioisotope thermoelectric generators (RTGs). This radioactive material produces heat when its starts decaying. The heat produced by it is then converted into electricity for vital tasks on spacecrafts, they said.

ORNL said in a statement that they now have a complete infrastructure that can provide steady and growing supply of Plutonium-238 for future space missions. The lab expects to produce 300 to 400 grams of Pu-238 per year and eventually ramp up annual production to about 1.5 kilograms.

According to NASA, the next space mission with plans for using an RTG is the Mars 2020 Rover, which is tentatively scheduled for launch in July 2020.

Production begins at Idaho National Laboratory, which stores the existing inventory of neptunium-237 feedstock and ships it as needed to ORNL. Engineers mix the neptunium oxide with aluminum and press the mixture into high-density pellets. They use the High Flux Isotope Reactor, a DOE Office of Science User Facility at ORNL, to irradiate the pellets, creating neptunium-238, which quickly decays and becomes plutonium-238.

The success of Wham and a team of engineers and technicians at ORNL comes two years after NASA began funding the DOE Office of Nuclear Energy through a roughly $15 million per year effort to revive the department’s capability to make plutonium-238.

Production begins at Idaho National Laboratory, which stores the existing inventory of neptunium-237 feedstock and ships it as needed to ORNL. Engineers mix the neptunium oxide with aluminum and press the mixture into high-density pellets. They use the High Flux Isotope Reactor, a DOE Office of Science User Facility at ORNL, to irradiate the pellets, creating neptunium-238, which quickly decays and becomes plutonium-238.

The irradiated pellets are then dissolved and ORNL staff use a chemical process to separate the plutonium from remaining neptunium. The plutonium product is converted to an oxide and shipped to Los Alamos National Laboratory, where the material will be stored until needed for a mission. Remaining neptunium is recycled into new targets to produce more plutonium-238.

There are currently only 35 kilograms, or about 77 pounds, of plutonium-238 set aside for NASA missions, and only about half of this supply meets power specifications. This is only sufficient to power two to three proposed NASA missions through the middle of the 2020s. Fortunately, the additional material that will be produced at ORNL can be blended with the existing portion that doesn’t meet specifications to extend the usable inventory.

With continued NASA funding, DOE’s Oak Ridge and Idaho national laboratories can ensure that NASA’s needs are met, initially by producing 300 to 400 grams of the material per year and then, through automation and scale-up processes, by producing an average of 1.5 kilograms per year.

“With this initial production of plutonium-238 oxide, we have demonstrated that our process works and we are ready to move on to the next phase of the mission,” Wham said.

The next NASA mission planning to use a radioisotope thermoelectric generator is the Mars 2020 rover, due to be launched in July 2020. The mission seeks signs of life on Mars and will test technology for human exploration and gather samples of rocks and soil that could be returned to Earth.

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