The article discusses the comparative characteristics of electron-betatron accelerators, linear electron accelerators, microtrons used in nondestructive inspection of large and thick-walled products. A description is given of a flaw detection installation based on a microtron with an energy of 8-12 MeV intended for the inspection of products containing steel 50-500 mm thick. The characteristics of flaw detection microtrons, existing or being developed, are given.