Spanish to English Tech/Engineering Nuclear Eng/Sci

This term appears in a service agreement in Mexican Spanish regarding the requirements for Provider X to provide services to a nuclear reactor, such as decontamination. Here is the context:

"En su propuesta, el Proveedor deberá describir paso a paso cada una de las etapas que forman parte del proceso de descontaminación y aplicación de metales nobles, indicando la interacción del químico empleado con el crud, así como el mecanismo de descontaminación y aplicación de cada etapa."

My translation:
"In its proposal, the Provider must describe each of the stages forming part of the process of decontamination and application of noble metals step by step, indicating the interaction of the chemical used with X, as well as the mechanism of decontamination and application of each stage."

What does "el crud" mean? Is it a term of art in nuclear engineering? Any help in this matter would be greatly appreciated!