CALIBRATION OF FAR-WEST TECHNOLOGY (FWT-60) RADIOCHROMIC DYE DOSIMETERS

Radiochromatic dye dosimetry was used to measure kilogray doses absorb ed hy various liquid samples during gamma ray exposure in a spent nucl ear fuel pool. The source of nuclear fuel was the Advanced Test Reacto r (ATR) at the Idaho National Engineering Laboratory (INEL). Calibrati ons were performed using a Co-60 source and were run on bare dosemeter s, as well as on dosemeters which were mocked to simulate the samples. These dosemeters were prepared as a dye-impregnated nylon film and ar e commercially available. When exposed to gamma ray doses of 0.5 to 20 0 kGy, a colour change occurs which has an optical density proportiona l to absorbed dose. The difference in the calibration curves demonstra tes the importance of irradiation of dosemeters under conditions as cl ose to the actual samples as possible. Since these dosemeters could no t be immersed directly in the organic solutions of interest, they were sandwiched between layers of Lucite and stainless steel. This simulat ed the conditions inside an irradiated sample and provides a practical method of measuring absorbed doses. The reproducibility of measuremen ts using the radiochromic dye dosemeters is also shown.