What is Cf-252?
Californium-252 (Cf-252) is one of 20 known isotopes of the element Californium. It is highly radioactive, with a half-life of 2.645 years and emits large amounts of neutrons. One microgram (μg) of Cf-252 emits 2.3 million neutrons per second; therefore, most applications require very tiny pieces of the isotope. Because of its radioactivity, Cf-252 must be carefully encapsulated for safety. An encapsulated piece of Cf-252 is referred to as a “neutron source.”
Cf-252 is used in a number of applications due to its radioactive properties, including Portable Isotopic Neutron Spectroscopy (PINS), Prompt Gamma Neutron Activation Analysis (PGNAA), scanners, reactor start-up rods, and more.
Production of Cf-252
As a man-made element, Californium is not found in nature and must be produced in nuclear reactors and particle accelerators. Californium was first produced in 1950 at the University of California’s Radiation Laboratory in Berkeley by bombarding a microgram of curium-242 with alpha particles.
Today the world’s supply of Cf-252 is made at two facilities: Oak Ridge National Laboratory (ORNL) in Tennessee and Research Institute of Atomic Reactors in Dimitrovgrad, Russia.
Production at ORNL is a three-step process:
Pellets of curium oxide are placed in the High Flux Isotope Reactor and bombarded with neutron flux, starting the process of beta decay that results in a mix of Cf-252 and other materials.
The Cf-252 mixture is transferred to a Radiochemical Engineering Development Center hot cell facility to separate and purify the Cf-252. This step takes place in a specialized ion exchange column in which the Cf-252 is flushed through resin until it is fully purified.
Using a chemical process called combined precipitation, a solid precipitate of Cf-252 and palladium is made. Then it is dried into oxide powder, compressed into pellets, and finally melted and rolled into thin wire (less than 1/10 inch in diameter). The wire is cut into shorter lengths before being encapsulated, decontaminated, leak tested, and shipped to Cf-252 suppliers, such as FTC.
Neutron Source Encapsulation
At Frontier Technology Corporation, we provide customers with Cf-252 neutron sources that are single- or double-encapsulated in stainless steel or Zircaloy-2 capsules. These capsules are sealed by TIG welding and further protected with specialized shielding materials and transported in Type-A shipping containers.
To ensure safety and contain potentially hazardous radiation during preparation, transport, and storage of Cf-252, it is crucial to use high quality, reliable shielding methods and materials
Shipping A Containers
Radioactive materials require specific types of packaging depending on the quantity and concentration of radioactivity. Our CF-252 neutron sources are shipped in Type-A shipping containers, which provide secure shipping for external radiation levels that do not exceed the legal shipping limits of 200 mRem/hour at the container surface or 10 mRem/hour at 1 meter away from these surfaces.
We offer standard and customized Type-A shipping containers which utilize proprietary packing material, water-extended polyester resin (WEP) to house and protect the encapsulated neutron sources in shipping and storage. At FTC all Type-A shipping containers are designed and constructed in-house, and their quality and performance are evaluated at each step in the manufacturing process.
Neutron radiation poses significant health risks; therefore, adequate shielding is required for protection. FTC builds custom neutron shielding walls to meet our customers’ unique project and application needs in a range of industries including:
- Military and defense
- Research and laboratory
- Oil, gas, sand, and shale
- Coal, cement, and minerals
A shield’s effectiveness comes from its ability to slow and block energized neutrons as they travel. Shielding material containing hydrogen is superior to dense material, such as lead, because hydrogen molecules are large so the neutrons collide with them readily and slow down. Compounds with a high concentration of hydrogen atoms, such as water and WEP, offer excellent protection, even in harsh environments, at an affordable price.
Our custom walls consist of a stainless steel outer structure with WEP inner core. They can be constructed with up to 12 inches of shielding thickness, up to 8 feet tall, and up to 6 feet wide. Isotope pass-through ports can also be incorporated. All of our walls are manufactured with each client’s personnel and environmental needs in mind.
FTC: A World Leader in Cf-252 Manufacturing and Design
Frontier Technology Corporation is a world-leading Cf-252 neutron source supplier. We offer over 40 years of experience in the logistics and shipping of Cf-252.
To learn more about the production of Cf-252 or about our Cf-252 sources and services, contact us or request a quote today.