{"operation":"document","citation":"18-0033","title":"Occupational Services Inc. — Hazardous Materials Safety Interpretation","source_type":"guidance","agency":"Pipeline and Hazardous Materials Safety Administration","status":"guidance","official":true,"published_on":"2018-08-07","effective_on":null,"summary":"18-0033 response to Occupational Services Inc. concerning 173.401, 173.403, 173.436.","machine_formats":{"json":"https://regulus.evalyn.ai/document/phmsa-interpretation-18-0033.json","markdown":"https://regulus.evalyn.ai/document/phmsa-interpretation-18-0033.md"},"app_url":"https://regulus.evalyn.ai/document/phmsa-interpretation-18-0033","source_url":"https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/docs/standards-rulemaking/hazmat/interpretations/60496/180033.pdf","body":"<<>>\n\nU.S. Department\nof Transportation\nPipeline and Hazardous\nMaterials Safety\nAdministration ·\n1200 New Jersey Avenue, SE\nWashington, DC 20590\nAUG O 7 2018\nLinda Bray\nSenior Health Physicist\nOccupational Services Inc.\n6397 Nancy Ridge Drive\nSan Diego, CA 92121\nReference No. 18-0033\nDear Ms. Bray:\nThis letter is in response to your March 2, 2018, email requesting clarification of the Hazardous\nMaterials Regulations (HMR; 49 CFR Parts 171-180) applicable to custom optical instruments\nthat use Thorium-232 (Th-232) as a filter. You note the following:\n• The Th-232 is an integral part of the lens and is deposited as a fixed coating over the lens\nsurface through a physical heating process.\n• The Th-232 is not a removable (nonfixed) contaminant; it is designed as a part of the\nfinished optical instrument fixed to the surface under normal conditions of transport.\n• The level of distributed activity on the lens typically exceeds the exemption in§ 173.401\nbased on the size of the lens, and for contamination limits in§ 173.403.\n• These lenses do not meet the definition of a sealed source, as the material is not\ncompletely encased by an enclosure.\nYou explain that while it is easy to determine the amount ofTh-232 deposited on the lens, it is\ndifficult to determine what is meant by concentration. You state that you would like to weigh\neach lens individually without any support structures such as holders, rings, or finished devices\nand then determine the concentration by dividing the Th-232 activity by the weight of the lens.\nWhen performing this calculation, the concentration is below the exempt values in§ 173.436.\nSpecifically, you ask whether a thin coating containing Th-232 applied to the surface of a lens\ncould use the weight of the lens to determine activity concentration in accordance with the values\nin § 173.436.\nThe answer is no. Because the lens is a solid object with a radioactive substance on its surface, it\nwould be more appropriate to consider the lens from a Surface Contaminated Object (SCO)\nperspective for Class 7 determination using the contamination limits in§ 173.403. However, if\nyou were to attempt to determine whether the TH-232 coating meets the definition of radioactive\n\n<<>>\n\nmaterial, then only the mass of the layer of Th-232 coating, not including the mass of the glass\nlens it is applied to, could be used for the activity concentration calculation as a Class 7\n(radioactive material).\nI hope this information is helpful. Please contact us if we can be of further assistance.\nSincerely,\n~ .~/ ~~- -\n., ~~ ~\nT. Glenn Foster\nChief, Regulatory Review and Reinvention\nStandards and Rulemaking Division\n\n<<>>\n\n/ - -\n, '\nl... l10 cl. ,,u ?,(,<...v\\\n§ I 7 3 ; Kelley, Shane (PHMSA) ; Foster,\nGlenn (PHMSA) \nCc: PHMSA Public Affairs \nSubject: FW: Question on Interpretation of Class 7 Exemption for Thorium Lenses\nHM Info Center & Standards,\nPassing this one to you for direct response.\nJoe\nFrom: Linda Bray [mailto:Lind~@J)ccserv.com]\nSent: Friday, March 02, 2018 1:42 PM\nTo: PHMSA Public Affairs \nSubject: Question on Interpretation of Class 7 Exemption for Thorium Lenses\nI am hoping to obtain assistance on the interpretation of how to apply the exempt concentration limits in 49 CFR\n173.436. We have a company manufacturing custom optical instruments (lens) that use Th-232 as a filter. They have\nthe appropriate NRC and state licenses to possess and distribute the material as exempt from licensing. The lens are\ndistributed to individuals who do not require a state or NRC license to possess the items. The lenses are made to order\nand contain varying levels of Th-232. The Th-232 is an integral part of the lens and is deposited as a fixed coating over\nthe lens surface through a physical heating process. So the Th-232 is not a removable (nonfixed) contaminant, it is\ndesigned as part of the finished optical instrument fixed to the surface under normal conditions of transport.\nThe level of distributed activity on the lens do typically exceed the exemption in 173.401 based on the size of the lens,\nfor contamination limits in 173.403. However, the activity levels are still very low which is why they qualify for the\nNRC exempt distribution license\nThese lens do not meet the definition of a sealed source or an article as the material is not completely incased by an\nenclosure around the Th.\nIt is easy to determine how much Th-232 is deposited on the lens. The difficult part is to determine what is meant by\nconcentration. We would like to weigh each lens individually without any other support structures such as holders, rings\n1\n\n<<>>\n\nor finished devices and then determine the concentration by dividing the Th-232 activity by the weight of the\nlens. When we perform this calculation the concentration is below the exempt values in 173.436. However, the\nguidance available in the interpretations is not clear on this issue. They do indicate for sealed sources like little H-3 vials\non glow in the dark watches to use the volume of the source without any additional support structures (i.e. the\nwatch). This makes sense so that people cannot abuse or dilute the requirements by adding nonessential weight to get\nbelow the exempt limits. However, this is not a sealed source which can be considered a separate item. The material is\nan integral part ofthe lens, and the material cannot be readily separated from the lens to represent a volume. We also\ndon't want to have to try to estimate an infinitely small volume of space to represent the source and way overestimate\nthe hazard for transport of these items which are used in a wide variety of common optical instruments.\nWe want to ensure we are performing the assessment correctly. Please advise on how the regulations for the exempt\nconcentration are to be applied in this situation as it impacts our shipping and also may impact customers who use the\nlens on a daily basis in devices which may also be moved over a public route.\nSincerely,\nLurda ~uztf\nSenior Health Physicist\nOccupational Services Inc.\n6397 Nancy Ridge Or.\nSan Diego CA. 92121\n858 558 6736 (Office)\n619 518 1662 (cell)\n2","truncated":false,"body_characters":6670}