CRUD Analysis – Radioactive Isotope Analysis in The Field
Entergy is an American energy company. They operate over 40 plants that turn nuclear, natural gas, coal, oil and hydroelectric power into electricity. Prior to remediation work in certain parts of their nuclear power plants, it is understood that radioactive deposits within pipework can significantly elevate ambient dose rates. Following the ionizing radiation regulation principle As Low As Reasonably Possible (ALARP), it is necessary to implement methods to reduce radiation exposure of the workforce.
The Radiation Protection Manager (RPM) for Entergy, is primarily interested in lowering source term inside pipes and having a method to determine the success of remediation processes. To do this, the RPM and his team need to know which isotopes are present and the relative contribution to dose for each isotope.
Challenges faced by Entergy
Within the laminate film layer in process pipes, a build-up of radioactive metals takes place. These are referred to as Chalk River Unidentified Deposits (CRUD). While radiochemistry is an effective tool for analysing the CRUD layer, the Entergy team need to know the composition of the CRUD layer as this relates directly to dose contribution.
Having the facility to characterize the CRUD layer, the RPM and his team can put in dose reduction measures specific to the heavy isotope(s) identified. For example by adding depleted zinc, which penetrates the laminate film and blocks Co-60 from bonding to the pipe wall. It should be noted that without a good understanding of the CRUD layer composition, it is impossible to determine the long term effectiveness of the removal process and therefore no guarantee that there will be a lasting result. Nuclide Identification enables accurate targeting and leads to ensure that the correct and most cost-effective removal methods are used.