Consistency and efficiency of standard swipe procedures taken on slightly radioactive contaminated metal surfaces.
In radiation work areas, a standard "swipe" procedure is widely used to evaluate the extent of contamination on surfaces. This report documents the variability in results of swipes carried out on various metal surfaces and the variability between different experienced health physics technicians. Also, there is an issue of the efficiency of the first swipe in terms of what fraction of the total absorbed surface contamination is detected by a swipe. The samples used for this study were metal surfaces uniformly exposed in the spent fuel pool of a nuclear power plant The primary surfaces studied were those usually found on spent fuel transportation casks (mainly 304 stainless steel in the U.S.), which are submerged in the spent fuel pools for loading or unloading of the highly radioactive fuel assemblies from nuclear power plants. These surfaces become contaminated with suspended and dissolved radionuclides, primarily 137Cs, 134Cs, and 60Co, in the spent fuel pool. A detailed evaluation was conducted of variations in the swipe measurements made on these metal samples using repeated swipes of the same area by the same technician and comparing swipes of one technician to those of another on similar surfaces. Rough surface finishes showed considerable inconsistency (approximately 30% variation) from one technician to another, but smooth surface finishes show substantially better consistency (<10% variation) between technicians. The "efficiencies" of a single swipe, particularly the initial swipe, expressed as a fraction of total "removable" contamination, ranged from approximately 10% to 20% for the stainless steel and titanium surfaces. Aluminum surfaces, on the other hand, showed much higher efficiencies on the initial swipe. However, in terms of the total contamination imbedded in the surfaces, the first swipe picked up only between 0.5% and 3% of the total adsorbed contamination. The overall results show the wide variations that routinely occur in swipe results on portions of surfaces that would be expected to give consistent results. These difference are an order of magnitude or more greater than the counting statistical errors.
Jung
H
H
Yonsee University, Seoul, Korea.
Kunze
J F
JF
Nurrenbern
J D
JD
D000327:Adsorption; D000535:Aluminum / Q000737:chemistry; D004866:Equipment Contamination / Q000706:statistics & numerical data*; D008670:Metals / Q000737:chemistry*; D009688:Nuclear Reactors / Q000295:instrumentation; D015588:Observer Variation; D011834:Radiation Monitoring / Q000379:methods* / Q000592:standards / Q000706:statistics & numerical data*; D011868:Radioisotopes / Q000032:analysis*; D015203:Reproducibility of Results; D013193:Stainless Steel / Q000737:chemistry; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry
D008670:Metals; D011868:Radioisotopes; D013193:Stainless Steel; D000535:Aluminum; D014025:Titanium