Tham khảo tài liệu 'radiation protection manual episode 6', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | EM 385-1-80 30 May 97 Table 6-4 Acceptable Surface Contamination Levels NUCLIDE a AVERAGE b c dpm 100 cm2 MAXIMUM b d dpm 100 cm2 REMOVABLE b e dpm 100 cm2 U-nat U-235 U-238 and associated decay products 5 000 15 000 1 000 Transuranics Ra-226 Ra-228 Th-230 Th-228 Pa-231 Ac-227 I-125 I-129 100 300 20 Th-nat Th-232 Sr-90 Ra-223 Ra-224 U-232 I-126 I131 I-133 1 000 3 000 200 Beta-gamma emitters nuclides with decay modes other than alpha emission or spontaneous fission except Sr-90 and others noted above. 5000 fi- 15 000 fi- 1 000 fi- a Where surface contamination by both alpha- and beta-gamma-emitting nuclides exists the limits established for alpha- and beta-gamma-emitting nuclides should apply independently. b As used in this table dpm disintegrations per minute means the rate of emission by radioactive material as determined by correcting the counts per minute observed by an appropriate detector for background efficiency and geometric factors associated with the instrumentation. c Measurements of square meter. For for each object. average contaminant should not be averaged over more than 1 objects of less surface area the average should be derived d The maximum contamination level applies to an area of not more than 100 cm2. e The amount of removable radioactive material per 100 cm2 of surface area should be determined by wiping that area with dry filter or soft absorbent paper applying moderate pressure and assessing the amount of radioactive material on the wipe with an appropriate instrument of known efficiency. When removable contamination on objects of less surface area is determined the pertinent levels should be reduced proportionally and the entire surface should be wiped. 6-10. Exposure Rate Surveys. In addition to contamination monitoring it is also important to assess exposure rates resulting from the storage and use of relatively large quantities of high energy beta or gamma emitters. This information is important in planning and evaluating the control .
