Radiation hardening, also known as “rad hardening,” and radiation survivability testing are of critical importance to defense, aerospace, and energy industries. Learn more about how Phoenix’s cutting-edge neutron generators are a proven solution for manufacturers in need of neutron flux cavities to optimize their parts for use in high-radiation environments.
Everyone knows that excessive exposure to radiation can cause severe damage to living things, but high radiation levels can also cause radiation damage to other objects, especially electronics. Ionizing radiation in particular, including directly ionizing radiation such as alpha and beta particles and indirectly ionizing radiation such as gamma rays and neutron radiation, is profoundly damaging to the semiconductors which make up the backbone of all modern electronics. Just one charged particle can interfere with thousands of electrons, causing signal noise, disrupting digital circuits, and even causing permanent physical radiation damage.
Of course, electronics make the world go round, and spacecraft, satellites, nuclear defense systems, military aircraft, and nuclear power stations just can’t operate without these electronic systems. These systems must be designed with robust, durable, nuclear-hardened electronics able to withstand high-radiation environments for long periods of time without breaking down or malfunctioning. That’s where radiation-hardened electronics can help.
Radiation hardening involves designing radiation-tolerant electronics and components that are tolerant of the massive levels of ionizing radiation, such as cosmic outer space radiation and high energy radiation within nuclear power plants. In order to test these components and determine whether they are sufficiently hardened, radiation hardened electronics manufacturers perform rigorous testing as part of their manufacturing processes. Components which pass these tests go into production and can be described as “radiation hardened”; components which do not go back to design.
Radiation Survivability Testing
The process of radiation hardening involves rigorous radiation survivability testing, also known as radiation effects testing. Radiation survivability testing involves bombarding materials with radiation to determine how long it can withstand harsh extremes of its operating environment and ultimately which material will be the best choice for a given radiation-hardened component.
Say, for example, you are responsible for designing the electronic components of a military satellite. A failure of the satellite’s electronics due to space radiation could endanger national security or put the lives of warfighters at risk. Both the electronics themselves need to be designed to be radiation-resistant; on top of that, the electronic components will need adequate protection as well in the form of shielding made from materials that are not easily penetrated by radiation – these are important steps in the radiation hardening of electronics. In the design phase, radiation survivability testing is a necessary method for ensuring that components operating in high-radiation environments will be able to function properly and with a lifespan that suits the operational needs of the system.
Radiation can adversely affect or damage materials in many different ways due to how high-energy radiation can disrupt their atomic structures. When designing components with radiation tolerance (to be tolerant of environments with high-radiation levels), manufacturers must take potential effects such as these into account:
When an object is exposed to neutron radiation, which is produced by nuclear fusion and fission reactions, the neutrons may be absorbed into the atomic nuclei. The process of absorbing a neutron can convert certain elements into unstable isotopes which then release radiation in of their own in the form of excess neutron radiation, alpha or beta particles, or bursts of gamma rays. This is called neutron activation and depending on the material, the object can remain radioactive for hours or days. Neutron activation can be a useful materials testing tool, but in other circumstances is less than desirable.
Ionization causes electrical breakdown, especially in semiconductors and integrated circuits, that can cause microelectronics to fail. Radiation exposure can cause all sorts of damage ranging from benign glitches and soft errors to catastrophic system failures. In particular, single event effects can change the logic of entire systems by altering one bit on integrated circuits, where the “single event” is an ion changing the state of a node on an electronic device; with radiation-hardened electronics, the risk of single event effects is mitigated. Radiation hardening and rigorous survivability testing are especially important in the design of microelectronics and electronic components since so much of the world’s vital infrastructure, such as GPS and weather forecasting, depends on satellites, which are exposed to large amounts of ionizing radiation in orbit around Earth.
Radiolysis occurs when radiation exposure causes chemical bonds to break down, causing structural weaknesses in a material that can lead to corrosion, cracks, or any other undesirable changes to its physical properties that could lead to degraded performance or failure. Radiation-hardened designs attempt to mitigate the effects of radiolysis.
In electronics radiation can be an important factor in the design process, but they are not the only materials for which radiation hardening and survivability testing are important. Normal concrete is especially susceptible to neutron activation and excess radiation exposure can cause a concrete bunker to become structurally unsound due to alterations of its physical properties. Because of this danger, special radiation tolerant concrete has to be used in the design and construction of nuclear reactor facilities that will not exhibit the same vulnerability to high levels of radiation. For example, the same type of radiation hardened concrete used for shielding in nuclear reactors is also used at Phoenix to make certain that our staff is not exposed to neutron radiation!
Radiation exposure can alter a material’s physical properties in many ways, including the following:
Hardening: Radiation exposure can physically strengthen a material, but at the cost of an often-undesirable loss of flexibility and elasticity
Embrittlement: One of radiation’s possible effects can also involve the material’s structure weakening, creating new stress points in the material and making it easier to fracture
Swelling: Due to thermal creep, a material exposed to radiation can exhibit swelling, which is especially dangerous for materials under pressure
Reduction of conductivity: Radiation exposure can reduce a material’s thermal or electrical conductivity
Ozone cracking: When radiation interacts with oxygen, it can produce excess ozone which can cause cracking and a loss of structural integrity in materials made from plastics, rubber, and other polymers.
Radiation hardening and survivability testing is primarily a need of the aerospace and defense sectors. Defense systems and infrastructure which are expected to remain functioning in the vicinity of a nuclear detonation must be tolerant of large amounts of radiation produced by the explosion, meaning they rely on radiation-hardened electronics. In addition, these systems must be able to remain functional in the event of secondary radiation effects, such as an electromagnetic pulse. For that functionality to be maintained through an event where these systems are exposed to high levels of radiation, we require radiation-hardened electronics to be used in the design.
In space, one of the greatest threats to our commercial and defense satellite infrastructure is the massive amounts of radiation that are produced by solar flares. Sufficiently powerful solar flares can even affect electronics on the surface of the Earth, causing power outages and failures of systems. Satellites, space shuttles, and space stations are especially vulnerable to solar flares, since they have no atmosphere to protect them. Radiation hardening is crucial to prevent damage to spacecrafts’ electronic systems from space radiation, as well as to protect human passengers from the direct effects of radiation exposure.
Phoenix’s high-yield neutron generators are an ideal source of radiation for rad hard research and radiation survivability testing. To simulate the conditions in space or within nuclear reactors, massive amounts of high energy neutron radiation bombards the material in question. After the material has been exposed to amounts of radiation consistent with the extremes of its operational environment, the material is analyzed for any signs of damage.
Most radiation survivability testing is carried out in nuclear reactor facilities, since the intense radiation within the reactor provides sufficient neutron yield to carry out the tests. However, using reactors comes with drawbacks, such as a large footprint and significant regulatory overhead due to the presence of high enriched uranium and the production of nuclear waste.
Phoenix builds a variety of high flux neutron generator systems with several different energy spectra intended to suit a wide variety of radiation and rad hard needs without the large footprint and safety concerns associated with reactors. Our system for radiation hardening and radiation survivability testing enables us to perform steady state irradiation testing with performance exceeding all existing solutions and with drastically reduced security costs and general risks.
Phoenix’s Radiation Survivability Solutions
- Easy-to-operate turnkey rad hard solution
- Minimal time to a typical radiation exposure fluence of 1 x 1012 n/cm2 (1 MeV neutron equivalent damage in silicon)
- Provides uniform neutron flux over test area of at least 10 x 10 x 10 cm3 to accommodate simultaneous exposure of large groups of electronic parts
- Several different neutron energy spectrums available
- System lifetime of greater than 10 years
- Fail-safe behavior
- Radiation shielding meets safety standards dictated under USA 10 CFR Part 20
- Easily operated by trained personnel and serviced by Phoenix operators
Phoenix develops the strongest compact neutron generators in the world. Our high-intensity neutron sources provide ample neutron flux for timely and efficient radiation hardening and effects testing. The compact design of our neutron generator systems also makes it possible for a rad hard and radiation effects testing system to be installed onsite in a reasonably sized protective enclosure, providing easy access to this necessary testing method for commercial or industrial applications.
The Phoenix Neutron Imaging Center, the first reactorless facility for high-quality fast and thermal neutron radiography, also produces enough thermal and fast neutrons to perform radiation hardening and survivability testing services without the inconveniences associated with reactor facilities.