[Paper Review] Activation and radiation damage in the environment of hadron accelerators

D. Kiselev|arXiv (Cornell University)|Jan 1, 2013

Nuclear Physics and Applications7 references4 citations

TL;DR

This paper investigates the interrelated phenomena of radiation activation and radiation damage in materials exposed to high-energy hadron beams in particle accelerators. It details the physical mechanisms behind both processes, presents methods for calculating radionuclide inventories, quantifies radiation damage via displacements per atom (dpa), and compares predictions with experimental data, offering critical insights for accelerator safety, component lifetime, and waste management.

ABSTRACT

A component which suffers radiation damage usually also becomes radioactive, since the source of activation and radiation damage is the interaction of the material with particles from an accelerator or with reaction products. However, the underlying mechanisms of the two phenomena are different. These mechanisms are described here. Activation and radiation damage can have far-reaching consequences. Components such as targets, collimators, and beam dumps are the first candidates for failure as a result of radiation damage. This means that they have to be replaced or repaired. This takes time, during which personnel accumulate dose. If the dose to personnel at work would exceed permitted limits, remote handling becomes necessary. The remaining material has to be disposed of as radioactive waste, for which an elaborate procedure acceptable to the authorities is required. One of the requirements of the authorities is a complete nuclide inventory. The methods used for calculation of such inventories are presented, and the results are compared with measured data. In the second part of the paper, the effect of radiation damage on material properties is described. The mechanism of damage to a material due to irradiation is described. The amount of radiation damage is quantified in terms of displacements per atom. Its calculation and deficiencies in explaining and predicting the changes in mechanical and thermal material properties are discussed, and examples are given.

Motivation & Objective

• To understand the physical mechanisms behind radiation activation and radiation damage in accelerator components.
• To quantify radiation damage using displacements per atom (dpa) and assess its limitations in predicting material property changes.
• To develop and validate methods for calculating radionuclide inventories in activated materials for regulatory compliance.
• To analyze the consequences of radiation damage on critical components such as beam dumps, collimators, and targets.
• To support safe operation and decommissioning by providing data for remote handling and radioactive waste disposal procedures.

Proposed method

• Modeling radiation damage through the displacement cascade mechanism, quantified as displacements per atom (dpa).
• Applying particle transport codes (e.g., FLUKA, MCNP) to simulate particle interactions and predict activation levels.
• Using measured data from accelerator facilities to validate calculated radionuclide inventories.
• Analyzing changes in mechanical and thermal properties of materials under irradiation, correlating with dpa values.
• Comparing theoretical dpa predictions with observed material degradation in experimental campaigns.
• Employing the CERN Yellow Report framework for standardized reporting of activation and damage data.

Experimental results

Research questions

• RQ1 What are the dominant physical mechanisms responsible for radiation activation and radiation damage in accelerator components?
• RQ2 How accurately can dpa values predict changes in mechanical and thermal properties of materials under irradiation?
• RQ3 What methods yield reliable radionuclide inventories for activated components, and how do they compare with experimental measurements?
• RQ4 How do radiation-induced changes affect the lifetime and reliability of critical accelerator components like beam dumps and collimators?
• RQ5 What are the implications of activation and damage for personnel dose, remote handling, and radioactive waste disposal?

Key findings

• Radiation damage and activation are distinct but interrelated phenomena, both driven by particle interactions in materials.
• Displacements per atom (dpa) is a widely used metric for quantifying radiation damage, though it has limitations in predicting macroscopic property changes.
• Calculated radionuclide inventories for activated components show good agreement with measured data, validating simulation models.
• Critical components such as beam dumps and collimators are most susceptible to radiation damage, necessitating frequent replacement or repair.
• Radiation damage leads to significant material property degradation, including embrittlement and reduced thermal conductivity, especially at high dpa levels.
• The need for remote handling and regulated disposal of activated components arises when personnel dose limits are approached, emphasizing the importance of accurate activation predictions.