thanks for your advise.
please let me to say you about my investigation till now:
I undestood that our subcontractor has been used gamma ray for RT without collimator so I advise them for using X-ray with collimator and I am waiting for thier report.
we are constrcuting a plant in a complex and we were facing with radigraphy problem;radiation of that cause on instruments on the other plants.
so UT dosen't work for piping beacuse of thier thickness.
what can we do for solving this problem.