Frontier Technology Corp (FTC) is a leading global supplier of californium-252 (Cf-252) neutron sources and radioactive shipping containers. We offer a full range of Cf-252 sources, rod assemblies, custom shielding and containers. In this guide, we answer some of the most frequently asked questions about Cf-252.

General Questions

What is californium-252? What does californium-252 look like?

Californium is a radioactive element with extensive industrial applications. First identified in 1950 at the University of California Berkeley, Cf-252 is the only isotope of californium that spontaneously emits neutrons, with a single microgram releasing up to 170 million neutrons per minute. Californium was the sixth transuranium element to be discovered, but it remains one of the only to be broadly used in applications such as nuclear start-up, sand, shale, oil & gas, and more.

Cf-252 is a silver-white metal, and the isotope has a half-life of just 2.65 years and a primary energy of 2 MeV. 

  • Californium-252 is the only isotope which spontaneously emits neutrons.
  • Californium-252 (Cf-252) was first identified in 1950 at the University of California in Berkeley, and was the sixth transuranium element to be discovered.
  • Cf-252’s half-life is 2.65 years.
  • Cf-252’s primary energy is 2 MeV.

How is californium-252 made?

Most of the Cf-252 used in the western world comes from Oak Ridge National Laboratory (ORNL), a facility that also serves as a leading global supplier of Cf-252. Scientists at ORNL use a high flux isotope reactor (HFIR) to produce Cf-252 and other isotopes. Using curium as a fuel source, the HFIR uses the flux trap principle to generate and trap neutrons, which can then be used in isotope production.

How is the activity of californium-252 measured?

  • Californium-252 is a radioactive metal that is measured in weight amounts of micrograms and milligrams.
  • All other isotopes are measured in the form of Curies.

What are the advantages of californium-252?

Cf-252 offers several key advantages that make it useful in a range of industries. For instance, Cf-252 offers extremely powerful neutron emission, so it is an ideal start-up source for nuclear reactors, which require a large and stable neutron source. Its powerful emission and portability also make the isotope useful for applications with size limitations such as boreholes and well logging. 

Cf-252 sources are temperature-stable, so they can operate in extreme high-temperature environments. Coupled with its ability to offer accurate insights about elemental/chemical composition, Cf-252 is practical for applications both in the field and in dedicated facilities. 

What is californium-252 used for?

Cf-252’s primary applications fall into two categories: sample analysis and neutron emission. In the energy industry, Cf-252 is used as a powerful neutron source to power nuclear reactors. Californium is used in the military and defense industries to detect hazardous materials – including IEDs –  via PINS systems. The isotope is also implemented in composition analysis in the oil and gas industry to analyze drill sites and in the coal and cement industries to detect the composition of the material in real-time.

Other sectors that rely on Cf-252 include various academic, governmental, and medical groups, who primarily use Cf-252 for research or spectroscopy.

How is californium-252 contained and protected?

Since Cf-252 is radioactive, it is essential that it be thoroughly contained to protect those who interact with the sources. At FTC, we offer both single and double encapsulation for Cf-252 neutron sources. An inner capsule can be used as a single encapsulated capsule whereas a double encapsulated capsule contains both an inner and an outer capsule. Our capsules are constructed with stringent care from durable stainless steel and/or Zircaloy-2.

How is californium-252 shipped?

With proper protection, Cf-252 can be safely shipped to virtually any location worldwide (please note that Frontier Technology Corporation does not ship to countries on the embargo list). The key is proper shielding with a Type-A radioactive shipping container. Frontier’s Type-A containers are composed of proprietary WEP shielding technology to ensure absolute containment. Critically, these containers comply with 10CFR50 Appendix B, U.S. Department of Transportation (USDOT) and U.S. Nuclear Regulatory Commission (USNRC) regulations, so you can trust in their absolute quality and efficacy.

Radioactive shipping containers must demonstrate the ability to prevent reactive elements from releasing neutrons under challenging transport conditions, which may include jostling or drops, exposure to precipitation, or even container penetration. An effective Type-A container withstands all of these conditions, preserving the neutron sources for safe transport. 

Why is californium-252 expensive?

Cf-252’s cost is due to its strength and unique analytical capabilities, but there are also other factors that contribute to this. The main driver of Cf-252’s price is limited supply. Californium-252 does not occur in the natural world; instead, it must be produced synthetically using specialized equipment, such as high flux isotope reactors. There are only two of these reactors worldwide, and the production process for Cf-252 can take up to two years, so the isotope remains scarce. Other factors that contribute to its prices include production and transportation costs.

What are the conversion measurements for 1 microgram (µg) of Cf-252?

  • 1µg = 2.31 x 106 neutrons/second (n/s)
  • 1µg = 0.5mCi
  • 1 µg = 0.02 GBq

What are Yellow III, Yellow II, and White I classifications?

Radioactive Category LabelsMaximum Surface mRem/hrTransport Index
White I0.50
Yellow II501.0
Yellow III20010

What is the proper label for shipping containers containing Cf-252?

    CLASS 7 UN3332

What is the proper labeling for EMPTY shipping containers previously containing radioactive material?

    CLASS 7 UN2908

Questions About Californium-252 at Frontier Technology Corporation

Explain the similarities and differences between FTC's Model 10 and Model 10S capsules?

  • Both are single-encapsulated sources
  • Both are certified as Special Form by IAEA.
  • Both are inner capsules for double-encapsulated sources. (Model 100)
  • Model 10 = 5.5mm x 24.8mm
  • Model 10S = 5.5mm x 11.9mm

How are FTC's sources sealed?

  • Welded with Tungsten Inert Gas (TIG) to meet Special Form requirements.

What is NIST-traceable, and are Frontier sources NIST-traceable?

  • NIST stands for the National Institute of Standards and Technology, and is an agency of the U.S. Department of Commerce. NIST measurements are the standard that all industrial measurements are held to.
  • ALL Frontier sources are NIST-traceable, and certification can be provided upon request.

Does Frontier provide certified neutron emission statements?

  • Yes, upon request.

What countries can Frontier ship Cf-252 sources to?

  • Every country in the world with the exception of those on the Embargo List.

Why choose Frontier Technology Corporation for californium-252?

Frontier Technology Corporation has over 40 years of experience in providing customer-tailored neutron sources, including PINS sources and nuclear start-up rods, along with Type-A shipping containers, custom shielding, and antimony-beryllium pellets. Throughout our decades of operation, we have become a leading global provider of Cf-252, and our quality standards are unmatched in the industry. 

FTC is licensed by the Ohio State Department of Health, and our design processes, fabrication, construction, and testing all comply with rigorous 10CFR50, Appendix B standards. We also comply with stringent ODH, Nuclear Regulatory Commission, ISO 2919, ASTM, and ANSI standards, and our neutron sources meet the requirements for IAEA Special Form Certification issued by the U.S. Department of Transportation.

As a leading global supplier of Cf-252, FTC has compiled extensive resources on californium, which we encourage you to explore:

For more information, or to learn more about Cf-252,  contact us or request a quote today.

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Frequently Asked Questions About Californium-252