Radiation Safety in Industrial Radiography

Abstract

Radiography technique is one of the most widely utilized non-destructive methods, used in industry to evaluate the structural integrity or find out the hidden details of an assembled structure. Since this method uses ionizing radiation, it is important to ensure not only the quality of product, but also the safety of the technician and the general public, as well as the protection of the environment. Since the technique deals with very large amounts of radiation during testing periods, improper practice could result in the technician and the public being exposed to a large dose of radiation in just a few seconds. Therefore, a high degree of care and professionalism is required for radiography work. Moreover, contamination from a corroded or damaged source can cause additional radiation hazards to radiography personnel. The radiography procedure for a job is developed in such a way that only a minimum dose is received during practice. This is achieved through the proper design of radiography exposure installation, proper training of radiation workers, strict adherence to radiation safety rules and proper selection and maintenance of radiation sources. This paper deals with various aspect of radiation safety norms to be implemented during the practice.

Introduction

Overexposure to ionizing radiation is harmful as it may cause cell damage to the exposed person. People are constantly exposed to a certain amount of radiation from natural and man-made sources. The intensity of radiation hazards is decided by several factors, such as their physical form and activity, energy, radiation type, etc. All radiation related hazards can be broadly classified as either external or internal hazards. External hazards are radiation from outside the body, while internal hazards arise when sources enter the human body and start irradiating at the place of their residence. Radiation hazards in industrial radiography are mainly caused by external sources, as x-rays and gamma rays are penetrating in nature and can irradiate organs deep inside the body. Therefore, radiation hazard evaluation is necessary in order to avoid alarming levels of exposure.

Radiation Protection and Dose Limitation

The International Committee on Radiation Protection (ICRP) has framed a set of guidelines for arriving at dose limitation:

1. No radiation practice shall be justified until it produces a net positive benefit.
2. Doses received during radiation work should follow the ALARA principle: As Low As Reasonably Achievable.
3. The Dose limit should not exceed prescribed limits.

The annual dose limit is designed in such a way that it prevents deterministic effects and limits probabilistic effects. As the deterministic effects have some threshold values, they can be avoided by lowering the dose value below the threshold value. The probabilistic effects do not have any threshold value; therefore, a certain amount of risk is always involved with all radiation work and the amount of risk is proportional to the dose received.