In my last post, I talked about how the U.S. had been converting uranium for old Soviet warheads into nuclear fuel for U.S. nuclear reactors. There are also other radioactive isotopes that the U.S. is buying from Russia.
Radioisotope thermoelectric generators (RTG) were developed to provide low power reliably for years. They are used in applications where there will be little or no human monitoring. These generators utilize a pellet of a radioactive isotope to provide the heat to generate the power. Plutonium-238 requires the least shielding and has the longest life of the isotopes that have been used in RTGs. All U.S. space exploration has been powered by Pu-238 RTGs. Solar panels are too big and inefficient, nuclear reactors are too big and complicated and there are no chemical batteries that could supply the power needed for space exploration.
The first satellites launched by the U.S. were powered by plutonium created by the U.S. However, U.S. military plutonium production stopped in 1992 and our supply of Pu-238 is rapidly dwindling. The Russians shut down their military production of Pu-239 in 2010. They are currently the only country that is still producing plutonium isotopes for industrial purposes. The most recent satellites launched by the U.S. are powered by Russian plutonium.
The U.S. has been buying Russian plutonium for years to power satellites but in 2009, after Russia wanted to renegotiate the contract and raise the price, the U.S. stopped purchasing from Russia. The situation at NASA is getting desperate. Space missions have already been cancelled because of a shortage of Pu-238. NASA currently has only sixteen kilograms of Pu-238 which it says is sufficient for the rest of this decade. That seems unlikely because a single satellite launched in 2006 needed eleven kilograms of Pu-238. In addition, U.S. military satellites also require Pu-238. Pu-238 has a half-life of about ninety years so if there are old stockpiles sitting around, they have already loss some of their energy. Without new sources of Pu-238, all future U.S. space missions may have to be cancelled.
NASA is forbidden from making its own Pu-238 so it is dependent on U.S. government programs for future production. It is estimated that the program will cost about a hundred million dollars. In 2012, only ten million dollars were spent. The Advanced Test Reactor near Idaho Falls, ID and the High Flux Isotope Reactor at Oak Ridge National Laboratory in Tennessee will be used to create about two kilograms of plutonium annual starting in 2017 if things proceed on schedule. Considering that a single satellite can require over ten kilograms of plutonium, that does not seem to be enough plutonium production to support the U.S. space program in the future.
The production of isotopes for industrials purposes is critical for the technologies of the twenty-first century. The United States is falling behind in the production of isotopes and really needs to focus money and resources on developing internal isotope production. If this is not done soon, then the U.S. will be at the mercy of other producers who will be able to charge whatever the market will bear. The U.S. will have to buy foreign produced isotopes or do without them.
