Partitioning and transmutation: A hype

(December 4, 1998) The Dutch Energy Research Foundation (ECN) in Petten organized a workshop on transmutation of nuclear waste on November 13, 1998. The researchers claimed that results are so favorable that further reprocessing and vitrification of nuclear waste better be stopped: if nuclear waste has been reprocessed and vitrified, transmutation is not possible any longer.

(503.4965) WISE Amsterdam -By transmutation of long-lived radio- isotopes, the ECN researchers claim, it is technically possible to shorten the period of storage to 1,000 years instead of the present 250,000 to 1 million year. If these results are realized in practice, they remark, public acceptance of future nuclear energy would be better. The large inventories of separated civil and military plutonium, more than 250,000 kg worldwide, could also be eliminated by transmutation. Too good to be true?

What is P&T?
Since some decades now, it is claimed by some nuclear researchers that Partitioning and Transmutation (P&T) is the solution for the problem of the storage of nuclear wastes. With successful P&T, this storage period could be brought down to 1,000 or even to 250 years, it is claimed. Partitioning is just another word for reprocessing of spent nuclear fuel. Transmutation is changing long-lived nuclides into other nuclides through irradiation with neutrons.

The ECN is doing research on partitioning and transmutation since about 1988. An actinide laboratory was built for ƒl 2 million (US$1.1 million). The present program, called Recycling of Actinides & Fission Products (RAS), is funded by the Dutch Ministry of Economic Affairs with ƒl 5.85 million (US$3.21 million) and the European Union (EU). The ECN cooperates mainly with French transmutation researchers. In Marcoule, France, new reprocessing technologies are being developed to separate all important actinides and long-lived fission products from spent fuel.
Two groups of radio-isotopes, ECN says, must undergo P&T:

• Actinides, most with very long lifetimes,
• Long-lived fission products (See Table I)

Actinides are formed by neutron irradiation of uranium-238. The group includes plutonium (which is the major actinide) and the minor actinides: neptunium, americium and curium. Spent fuel contains± 1% plutonium and ± 0.1% minor actinides. Fission products represent about 3.4% of spent fuel. The rest (95.5%) are uranium isotopes, mainly uranium-238.
ECN concentrates on life-reduction of actinides. They have experimented with transmutation of americium-241, which seems to be a very cunning choice. Their result: "transmutation of 35% of americium-241 in a uranium-free fuel by `fast neutron' irradiation". It all sounds optimistic, but is it true?

Does it work?
No, and for a number of reasons.

• The isotope ECN experimented with is not a long-lived one. Americium-241 has a half-life¹ of "only" 430 years. Americium-243 should have been a more logical choice: it has a halflife of 7,400 years. The technique of partitioning and transmutation of americium-241 is internationally rather advanced: ECN estimates it would take only some decades before it can be industrialized. Neptunium-237, with a half-time of 2.1 million years or curium-245 with a half-life of 8,500 years, are much more difficult to separate and transmute.
• The present reprocessing plants don't separate all actinides, only plutonium. New reprocessing technologies which separate all actinides are only in the research stage. It is questionable if such new reprocessing plants would be built. Reprocessing costs are to be much higher than at present, while the trend is that reprocessing costs have to come down significantly if nuclear energy is to compete with other methods of electricity production.
• Many fission products (28% of them) are long-lived isotopes: zirconium-93, cesium-137, iodine-129, palladium-10. These fission products cannot be separated in present reprocessing plants and will not for at least the next two decades. Moreover, the ECN researchers admit that transmutation of several fission products is not considered feasible.
• Direct storage of spent fuel at reactor sites is much less dangerous and many times cheaper: less transports; almost no discharges of radioactive elements into the environment; many times less volume of waste and less proliferation risks.
• Transmutation à la ECN needs the large-scale introduction of fast breeder reactors (FBR) and the development of new types of nuclear fuel, which do not contain uranium-238. In the last decade, almost all FBRs have been closed due to technological and economical problems. The method promoted by Nobel prize winner Rubbia, transmutation in Thorium Accelerated Based Systems, so-called Rubiatrons (or TABS), is only in the paper stage and is also based on Fast Breeders. Realization will take billions of dollars and many decades. The present Light Water Reactors are not suited for transmutation of acinides or long-lived fission products.
• To reach practical results (almost 100% transmutation of all long-lived radio-isotopes is necessary), long-lived fission products and all actinides must undergo many cycles of reprocessing and transmutation. This has grave environmental, risky and financial consequences: each time spent fuel is reprocessed, much radioactivity is released into the sea and into the air. Reprocessing plants are notorious for their large discharges of radioactivity into the environment.

Spent fuel and reprocessed materials, including plutonium, have to be transported worldwide which endangers people along the routes and has proliferation problems.

• The planned construction of new reprocessing plants and new fast breeders is neither economically nor politically attainable.
• An almost 100% separation during reprocessing of all long-lived isotopes is necessary. If only 10% of the isotope stays behind, the storage period of nuclear waste will remain some hundreds of thousands of years. This advanced reprocessing techniques do not yet exist.

The researchers at the ECN admit their research is only directed on the future: to enable expansion of nuclear energy later on. It has no relevance whatsoever for present-day nuclear energy problems. Their claim that transmutation is the solution for the nuclear waste problem is unfounded and sounds like mere fraud.
Their attitude is to get more money for further research.
All over the world, more and more money is spent on transmutation research: mainly in the US, France, Japan.
P&T research began over 20 years ago and many more decades of research is needed, researchers admit. The nuclear lobby presents it as the final nuclear waste solution which would bring about public acceptance of nuclear energy. But even experts of the International Atomic Energy Agency (IAEA) are critical.

Drawing conclusions on partitioning & transmutation is easy:

• Partitioning and transmutation is a hype: the next decades
  it is neither technically nor practically possible, because existing reprocessing plants separate plutonium, but not other actinides or long-lived fission products;
• For the largest part of spent fuel, it cannot be a solution: P&T presumes reprocessing of spent fuel, but about 2/3 of all spent fuel is not and will not be reprocessed;
• P&T can only be achieved after building new reprocessing plants, new fast breeder reactors, Rubbia accelerators and designing and making new types of nuclear fuel which would take at least several decades and cost many billions of US dollars; and
• Even partial transmutation would have very negative safety, environmental and economic consequences.

Partitioning and transmutation is not and cannot be a solution for nuclear waste problems. Therefore all money spent on it is spilled: funding and research should be stopped by the Netherlands and by the European Union.

Tabel I: Half-lifes of some radio-isotopes: