Energy Deposition, DPA and other Specialist Analysis

Ionising radiation can present a hazard to materials and components as well as to biological matter. Examples of how this can occur include heat generation, resulting in changes to material properties or changing the reaction rate in the local environment; or displacement of atoms (DPA) in a material lattice, degrading structural performance or resulting in failure of electronic components.

What is Energy Deposition, DPA and other Specialist Analysis?

Specialist analysis through Monte Carlo or deterministic methods can calculate the amount of energy deposited by radiation in matter or numbers of displaced atoms. Similarly, these methods can also be applied to other specialist radiation physics analysis. This can include radiolysis rates, detector responses, radioisotope yield for radioisotope manufacture or bremsstrahlung from trace ion interactions in imperfect vacuum.

These are just a few examples of specialist radiation physics analysis that the team at TÜV SÜD has performed for various clients. However, there will be other applications of such specialist skills and the number of applications is likely to increase as physics, medical and nuclear research and understanding continues to develop and improve through the 21st century.

Why is Energy Deposition, DPA and other Specialist Analysis Important?

The significance of conclusions of specialist analysis depends very much on the application.

Regarding nuclear safety significance, radiation doses to components that provide a safety function (e.g. polymer seals, door interlock detectors/cameras) can result in their failure. Calculations can help predict whether or not a component will fail within the forecast operational lifetime and if so, what the replacement schedule should be. Also, energy deposition by radiation can result in heating of components and/or the local environment. This can have an accelerating effect on chemical reactions (e.g. increasing corrosion rates or hydrogen production rates) or can result in pressurisation of sealed containers (e.g. transport containers).

Radiation induced atomic displacements (DPA) can cause failure of electronic components and can result in changes to structural properties of materials; the latter being particularly important in fusion first wall analysis or target components for linear accelerators. Another means of metallic properties being changed in such environments, is the build-up of both stable and unstable activation products which can have an alloying effect. Such analysis is critical in determining maintenance and replacement schedules or developing product specifications when considering components in these environments.

Calculation of activation products can also be important when radioisotope production is intentional. For research concerning transmutation of long-lived nuclear waste into shorter-lived isotopes, the yield and species of daughter isotopes can be estimated. Similarly, when considering production of isotopes for medical or industrial uses, performing detailed calculations in an effort to improve understanding of how isotope yield changes with various parameters and understanding what by-products are likely to be produced can greatly assist with design feasibility studies and risk mitigation.

TÜV SÜD's Services

TÜV SÜD can offer a range of services to support specialist analysis including:

• Energy deposition analysis – Calculation of decay heat and/or deposited energy to provide data to engineers with which they can perform the relevant thermal calculations.
• DPA analysis – Calculations to determine number of displaced atoms due to incident ionising radiation.
• Calculation of residual isotope inventories – Simulations can also be used to estimate both stable and unstable residual isotopes generated by incident radiation.
• Other specialist analysis – Given the wide range of applications of these skills, contact us with your specialist radiation physics analysis requirements to see if we may be able to help.