Nuclear material and radioactive sources are widely used for the benefit of mankind mainly in nuclear power plants for electricity generation, hospitals for diagnosis and treatment, industries, research and development activities in the country. In spite of observing safety precautions during the operation of nuclear installation and radiation facilities, there are chances that radiation workers may be exposed to radiation which could be hazardous for their health. Therefore, monitoring of radiation exposure is very important for taking necessary protective measures to avoid any over exposure. PNRA requires that the radiation workers should be monitored for occupational exposure in order to be vigilant of radiation doses. PNRA has established National Dosimetry and Protection Level Calibration Laboratories (NDCL) at different places in the country for independent monitoring and cross verification of radiation exposure of workers. This setup has improved regulatory oversight at nuclear installations and radiation facilities across Pakistan. NDCL have following functions:
External Dosimetry
External dosimetry laboratories (labs), established at Islamabad and Karachi are used for monitoring of external doses of radiation workers at the licensed facilities. These labs are equipped with Thermo-Luminescent Dosimeter (TLD) Readers, Whole Body and Extremity TLDs and employs Thermo-Luminescent Dosimetry technique for measuring external exposure to radiation workers. PNRA also performs personal dose assessment of first responders in case of any nuclear or radiological emergency at nuclear power plants or radiation facilities.
Internal Dosimetry
Internal Dosimetry Laboratories have been established in Islamabad, Chashma and Karachi. These labs are capable to assess the ingested or inhaled radio-nuclides through direct as well as indirect methods. The direct measurement of radioactivity within the human body is conducted by Whole Body Counters (WBC). Radiation workers employed at the nuclear power plants are routinely monitored for internal radiation doses at these labs. Whereas, the indirect measurement method involves internal dose assessment by counting the activity excreted from the human body. This technique employs bio-assay of body fluids (urine) using alpha, beta and gamma spectroscopy.
Protection Level Calibration
Protection Level Calibration setup has been established at PNRA for
calibration of radiation detection equipment according to international practices. This
setup is equipped with gamma irradiators, ionization chambers and calibration phantoms.
This arrangement has enabled PNRA to ensure through cross verification that the equipment
used by the licensees of nuclear installations and radiation facilities for radiation dose
monitoring are appropriately calibrated and the results are accurate.