Gamma Radiation Measurements
DEQ performs “real-time” radiation measurements to monitor and gauge exposure rates in the environment on and around the INL. Real-time measurements are collected using a Reuter-Stokes RSS-112 High-Pressure Ion Chamber (HPIC) Environmental Monitor, calibrated at a range of 0 to 100 mR/hour, that transmits five-minute average exposure rates to a personal computer used for polling data in DEQ's Idaho Falls office. Data are stored in a database with average exposure rates determined for five-minute periods, weekly, monthly, and quarterly.
DEQ conducts independent HPIC radiation monitoring to:
- Verify and supplement radiation monitoring conducted by the US DOE M & O contractor for INL (BEA) and the DOE offsite monitoring contractor (ESER)
- Independently determine whether INL activities pose a threat to public health and to the environment
- Provide historical and real-time background measurements and timely measurements in the event of a future atmospheric radiological release due to INL operations or a radiological accident
Many sources of penetrating radiation are measured by HPIC, including cosmic radiation from deep space, ionizing radiation from the sun, gamma-emitting radionuclides distributed in the soils, and air-borne gamma-emitting radionuclides (cloud gamma) attributed to radon and its progeny as well as potential contributions from INL operations.
It is neither feasible, nor appropriate, for DEQ to monitor at all possible locations. Therefore, locations are prioritized in terms of areas where climatology and dose projection models predict that contaminants are representative of transport and accumulation mechanisms. Additionally, HPIC monitoring locations are co-located with NOAA Mesonet towers to provide redundancy in data collection (by NOAA) in the event that the DEQ telemetry system and polling hardware fail.