SAMPLE PREPARATION LABORATORY HEPA FILTER CHANGE DOE/ERSP PROCEDURENO.17 APPROVED: L DATE DRAFTED: 30 January 1978 7 February 1978 by Don R. Martin (ERSP Manager) Introduction By the end of six months of operations about 6000 soil samples will have been processed in this facility, and 10% are ballmilled. Assume that each averages 100 grams and that 0.1% of the material is trapped in one or the other of the 4 HEPA filters. One can further assume then that each filter will accumulate about 15 grams of potentially radioactive material. The average activity (238, 239py) for the samples is 10 pCi/g. Therefore one could expect a total of no more than 150 pCi of 238, 239py to accumulate on each filter in a 6-month period. Due to the inherent difficulties of determining the levels of alpha radionuclides imbedded deep within filter material, the loaded filters should be treated as though they contain significant levels of Pu, Am and U. Il. Procedure When the Dwyer Model 25 manometersindicate, in inches of water, that the red lined partial pressure levels have been reached for a hood, filter and blower combination, the HEPA filters are to be changed. The drying oven hood red line is set at 0.75 inch of water; The ballmill hood red line is set at 0.80 inch of water; The muffle oven hood red line is set at 0.75 inch of water; and The grinding hood red line is set at 0.45 inch of water. A. Erect wind screen. B. Don mask and protective clothing. C. Disconnect the downstream flex pipe from the filter opening. D. Seal in plastic the downstream pipe opening and the filter opening. Disconnect the upstream flex pipe from the filter. F. Seal in plastic the upstream pipe opening and thefilter opening. G. Double bag the loaded filter and box. H. Dispose of as low level radioactive waste. 1 Install new HEPA filter and establish new manometereut off setting. d. Survey the personnel and roof area to verify that they are free of contamination. A-17-1