Experience with Ontario Hydro's in place carbon filter testing

It is now 5 years since Ontario Hydro's first use of freon to test for both integrity and carbon quality in Nuclear Generating Station carbon ventilation filters. The method has since been refined and the equipment modified and the test has now become routine. Alongside the freon test, a 24 hour methyliodide desorption test is also routinely performed on the worst (most desorbing) filters as indicated by the freon test. The method uses non-active methyliodide injection and neutron activation analysis of dual carbon sampling beds. A chemical means of iodine analysis to replace the neutron activation analysis is being pioneered to streamline the process and render it fully field applicable. The method is still developmental, but field testing is anticipated in 1992. In the interim some TEDA impregnant analysis of carbon grab samples has been carried out. In this work, data on apparent TEDA loss from Emergency (standby) filters over a 3 year period is presented. The discussion includes the development of the freon test, replacement of the laboratory test, the in-place methyliodide desorption test, and the use of the methyliodide desorption test at the Pickering Nuclear generating Station. Alternative testing strategies, experience with emergency filters, and anticipated future developments are described. 6 refs., 11 figs., 6 tabs