What Is Molybdenum-99 (Mo-99)?


Molybdenum-99: Delivering Life-Saving Diagnostics

Molybdenum-99 (Mo-99) is the radioactive isotope that enables many diagnostic nuclear medicine procedures such as SPECT scans, which can detect many potentially life-threatening conditions and help patients receive the potentially life-saving treatments they need. As the parent isotope of technetium-99m, a light-emitting element used to diagnose and stage diseases such as cancer and heart disease in 56,000 Americans every day, Mo-99 is one of the world’s most valuable radioisotopes.

Our fusion-based medical isotope production system produces high-specific-activity molybdenum-99 using a proprietary fusion-fission process, without the need for a conventional reactor and the use of inefficient highly enriched uranium. We believe that our production of Mo-99 in the United States will mitigate, if not prevent chronic shortages by producing the isotope in an efficient, clean, low-cost manner compatible with the existing radioisotope supply chain.

What is molybdenum-99 used for?

Molybdenum-99 is the parent isotope of technetium-99m, a gamma-emitting isotope used as a radioactive tracer in medical imaging procedures such as SPECT scans. Tech-99m is used in tens of millions of medical diagnostic procedures around the world every year. It is a critical medical tool for diagnosing heart disease, bone disease, and cancer.

Tech-99m has a very short half-life; of any given supply, nearly all of it will decay in under a day. Its short half-life makes it extremely useful as a tracer, but also makes it impossible to stockpile. Tech-99m has to be used nearly as soon as it is produced. Mo-99 has a much longer half-life that allows it to be shipped from production facilities to radiopharmaceutical facilities where it can be processed in a technetium generator.

Nuclear medicine applications of molybdenum-99

Because Technetium-99m is sourced exclusively from molybdenum-99, molybdenum is a critical enabler of an extremely wide range of nuclear medicine diagnostic procedures which rely on Tech-99m, such as:

  • Single photon emission computed tomography: SPECT scans use gamma-emitting isotopes, most commonly Tech-99m, to produce a 3D image of a patient’s body using a rotating gamma camera
  • Bone scans: Tech-99m and medronic acid pinpoint regions of active bone growth in the body
  • Myocardial perfusion imaging: A form of functional cardiac imaging used as a stress test for the heart
  • Cardiac ventriculography: Tech-99m acts as a tracer to evaluate cardiac disorders such as coronary artery disease, valvular heart disease, congenital heart diseases, and cardiomyopathy
  • Functional brain imaging: By pinpointing areas of the brain with high blood flow, Tech-99m can be used to map the regional metabolic rate of brain tissue
  • Sentinel-node identification: Tech-99m can identify the predominant lymph nodes draining a cancer, such as breast cancer or malignant melanoma
  • Immunoscintigraphy: Tech-99m can be incorporated into a monoclonal antibody capable of binding to cancer cells to detect hard-to-find cancers such as intestinal cancer
  • Blood pool labeling: By combining Tech-99m to a tin compound, it can be used to map circulatory system disorders such as internal bleeding and heart wall motion abnormalities

Technetium-99m is also used in conjunction with pyrophosphate to gauge damage to the heart after a heart attack, with sulfur to image the structure of the spleen, and with technetate(VII) to detect Meckel’s diverticulum.

Is molybdenum-99 natural?

Molybdenum, the fifty-fourth most abundant element in the Earth’s crust, has seven naturally occurring isotopes out of thirty-five known isotopes, and molybdenum-99 is not one of them. Mo-99 is not a naturally occurring isotope of molybdenum. SHINE has developed an innovative process to produce Mo-99 through the intense neutron bombardment of low-enriched uranium.​

When uranium-235, the most fissile isotope of uranium, is subjected to neutron radiation, it undergoes fission and produces many lighter isotopes, including Mo-99.

Though uranium fission can happen naturally in the case of a natural fission reactor (the only known instance of which occurred in Gabon, France two billion years ago), only man-made fission reactions with sufficiently enriched uranium are sufficient to produce Mo-99 in any appreciable quantity.

What type of radiation does molybdenum-99 emit?

As they decay, unstable isotopes expel energy in the form of excess alpha, beta, neutron, or photon radiation in order to reach a more stable form. Molybdenum-99 emits beta radiation, or the release of an energized electron from the atomic nucleus, as it decays into its daughter isotope, technetium-99m.

A common misunderstanding about Mo-99 is that it is the gamma-ray-emitting isotope used in many diagnostic nuclear medicine procedures such as SPECT scans and bone scans. Often, Mo-99 is conflated with Tech-99m due to the former’s utility in producing the latter.

Where is molybdenum-99 produced?

Currently, the method most commonly used to produce molybdenum-99 is the use of non-power-generating fission reactors. These reactors previously used highly enriched uranium as fuel to produce Mo-99, but most have switched over from HEU to low-enriched uranium out of nuclear proliferation and security concerns.

There are only a handful of such facilities in the world, located in Europe, South Africa, and Australia. These few reactor facilities, all of which are located on the eastern hemisphere, currently provide the vast majority of the world’s Mo-99.

Due to the precariousness of this situation, many new methods are being considered for the reliable domestic supply of Mo-99, including our proprietary fusion/fission isotope production process.

Why are there shortages of molybdenum-99?

Molybdenum-99 is an unstable radioactive isotope and thus eventually decays into other elements. With a half-life of 66 hours, it takes just under three days for half of any given quantity of Mo-99 to decay into technetium-99m. Tech-99m decays even more rapidly, with a six-hour half-life, into technetium-99, which is medically useless, and then into stable ruthenium. In other words, the supply of Mo-99 is constantly running out and it is impossible to stockpile the isotope. Therefore, isotope production facilities must be continually in operation to provide a reliable domestic supply.

Because there are so few reactor facilities producing Mo-99, one reactor temporarily shutting down for maintenance or unforeseen issues imperils the entire global Mo-99 supply chain, leading to shortages across the world of the isotopes necessary to deliver lifesaving medical care. The average age of these reactors is between 50 and 60 years old, and most of them are expected to go offline in the next five to 10 years—leaving only the Australian reactor left online by 2030.

How is molybdenum-99 produced?

There are multiple ways to produce molybdenum-99, the most common among them being reactor-driven Mo-99 production. We believe that the SHINE isotope production process is the best way to produce Mo-99, and that in the future our molybdenum-99 production facilities will satisfy most of the world’s demand for this critical medical radioisotope.

Mo-99 is produced by irradiating enriched uranium with neutron radiation. When the uranium undergoes fission, it splits apart into various lighter elements. In the Mo-99 production facilities, the Mo-99 is separated from the rest of the fission byproducts, then packaged and sent to radiopharmaceutical facilities all around the world where it can be processed into technetium-99m and used in medical diagnostic procedures.

After a global medical radioisotope shortage in 2008-2009 due to several Mo-99 providing reactor facilities going offline, the U.S. Department of Energy sought to develop novel methods of producing this critical isotope. With support from the DOE, many companies have looked into new ways to produce Mo-99. Some of these methods involve transforming other isotopes of molybdenum, such as Molybdenum-98 or Molybdenum-100, into Mo-99 through nuclear transmutation instead of relying on uranium fission.

Our isotope production method relies on using proprietary nuclear fusion technology to transform recycled uranium into lifesaving medicine. While all of the proposed methods for producing Mo-99 have their own advantages and disadvantages, we believe that our method is the best suited for supplementing and eventually replacing the aging reactors that currently provide the world with this critical diagnostic tool.

The SHINE molybdenum-99 production process

Our molybdenum-99 production process utilizes our revolutionary deuterium-tritium fusion neutron generators to produce Mo-99. Our DT neutron generators use a compact particle accelerator to fuse deuterium and tritium, two isotopes of hydrogen, and create very high, sustained yields of neutron radiation. With this system, we have set a record for the most powerful sustained fusion neutron source built by humanity.

Low-enriched uranium for Mo-99 production

The high yields of neutron radiation we produce induces fission in low-enriched uranium. We source our LEU from decommissioned nuclear systems as a way of recycling uranium that is no longer in use. Highly enriched uranium from these decommissioned systems is diluted, or downblended, into LEU and dissolved in water to create uranyl-sulfate. This uranium solution serves as the target for the neutron beam created by our DT neutron generators.

As in a fission reactor facility, the fission of LEU produces produces Mo-99 as a byproduct, along with other isotopes with medical applications. Our proprietary isotope extraction and purification process separated our Mo-99 from the uranium solution and ensures that it meets all medical and customer standards.

Advantages of our molybdenum-99 production

We believe that our fusion-based molybdenum-99 production process is the best and most reliable way to produce Mo-99. For the following reasons, our isotope production process shows clear advantages over all other methods for producing this vital isotope:

Removal of nuclear fission reactors

By utilizing fusion-produced neutrons, we eliminate the need for fission reactors. By eliminating fission reactors, we also eliminate almost all of the nuclear waste associated with running these reactors.

While current Mo-99 production facilities are not used to generate power, they produce much of the same radioactive waste byproducts as power-generating fission reactors. Reactorless methods of isotope production have a clear advantage in that they produce far less waste than nuclear reactors.

Removal of highly enriched uranium

HEU, the most widely used form of uranium for nuclear power, presents a major nuclear proliferation concern. Over the past few years, most reactor facilities producing Mo-99 have begun phasing out HEU for LEU in order to address this concern. By cutting down on HEU used for isotope production, it is easier to prevent HEU from falling into the wrong hands.

Our production process removes HEU from the equation in more ways than one. The LEU we use in our isotope production system is created by taking HEU from decommissioned nuclear systems and diluting it so that fissile uranium comprises a much lower percentage of its total mass. This alleviates the concerns with storing HEU that is no longer in use. By using LEU downblended from HEU, we eliminate the chance of HEU used in the production process being diverted for nuclear weapons production. Our isotope production method is the best way to produce Mo-99 without highly enriched uranium.

Reusable target liquid

Unlike reactor facilities, our Mo-99 production system does more with less. Our liquid LEU target solution can be recycled into our production system after each use, dramatically decreasing the amount of uranium needed to produce Mo-99. This recyclable target solution further reduces nuclear waste produced, makes separating the isotopes easier, and decreases the amount of uranium required to make a given quantity of Mo-99.

Commercially viable Mo-99 produced

The key advantage our Mo-99 production process has over other competing methods of isotope production is its commercial viability. Unlike our competitors, our Mo-99 production system has been designed from the ground up to be fully compatible with the existing medical isotope supply chain. We produce high-quality, high-purity, high-specific-activity Mo-99 that is immediately ready to be delivered to medical facilities for nuclear medicine procedures.

Our Mo-99 production facility in Janesville, Wisconsin, is anticipated to have the largest dedicated medical isotope capacity in the world, with the ability to reliably place critical medical isotopes into the hands of U.S.-based clinicians as much as 24 to 36 hours sooner than current sources. At full capacity, we believe the facility will be capable of satisfying current U.S. demand for Mo-99 or the equivalent of over one-third of the world’s current demand.

Our upcoming production facility in Veendam, the Netherlands, will have a similar capacity, allowing us to produce two-thirds of the worldwide need for Mo-99.