Radiological implications of readings with a NaI(Tl) monitor set on an ion exchange resin column for purifying primary coolant water.
Changes in readings of a NaI(Tl) monitor set on the surface of an ion exchange resin column used to purify primary coolant water at the Kyoto University Research Reactor were examined with mathematical models to clarify the radiological meanings. The concentration distributions of the nuclides in the interstitial water of the resin bed and those adsorbed on the resins were determined by use of the dispersion-convection theory coupled with the linear isotherm adsorption relation. The adsorbed amount that was assessed by this model was theoretically related to that made by a compartmental model. The buildup concentrations of nuclides in the core water and the decreased accompanying power operation and shut-down were modeled using the value representing the cleanup rate by the purification circuit. The values of this parameter were determined by the least squares method for observed concentrations of 24Na, a major radionuclide in the core water. Recognizing that the adsorption band had remained within the top 10 cm during the circulation of water through the column, the change in the amount of radionuclide adsorbed on the resin was calculated using a compartmental model. The amount of radionuclide adsorbed on the resin predicted by the model agreed well with the readings of the NaI(TI) monitor. Factors that affect the reading are discussed in relation to early detection of fuel defects.
Research Reactor Institute, Kyoto University, Osaka, Japan.
M
M
Fukui
D000327:Adsorption; D002852:Chromatography, Ion Exchange / Q000295:instrumentation; D008956:Models, Chemical; D009688:Nuclear Reactors; D011834:Radiation Monitoring / Q000295:instrumentation; D011868:Radioisotopes / Q000032:analysis*; D012974:Sodium Iodide; D012979:Sodium Radioisotopes / Q000032:analysis; D013696:Temperature; D013793:Thallium; D014875:Water Pollutants, Radioactive / Q000032:analysis* / Q000302:isolation & purification
D011868:Radioisotopes; D012979:Sodium Radioisotopes; D014875:Water Pollutants, Radioactive; D013793:Thallium; D012974:Sodium Iodide