Section 5M. As used in sections five M to five P, inclusive, or the rules and regulations adopted under said sections, the following words shall, unless the context clearly indicates otherwise, have the following meanings:—
''By-product material'', any radioactive material, except special nuclear material, yielded in or made radioactive by exposure to the radiation incident to the process of producing or utilizing special nuclear material.
''General license'', a license effective under rules and regulations adopted by the department without the filing of an application with the department or the issuance of licensing documents to particular persons to transfer, acquire, own, possess or use quantities of, or devices or equipment utilizing radioactive material.
''Person'', any individual, corporation, partnership, firm, association, trust, estate, public or private institution, group, agency of the commonwealth other than the department, any political subdivision of the commonwealth, any other state or political subdivision or agency thereof, and any legal successor, representative, agent or agency of the foregoing, but not including federal government agencies.
''Source material'', uranium or thorium, or any combination thereof, in any physical or chemical form; or ores which contain by weight one-twentieth of one per cent or more of uranium, thorium, or any combination thereof. Source material does not include special nuclear material.
''Special nuclear material'', plutonium, uranium 233, and uranium enriched in the isotope 233 or in the isotope 235, but not including source material; or any material artificially enriched by any of the foregoing, but not including source material.
''Specific license'', a license, issued to a named person upon application filed under the rules and regulations adopted by the department, to use, manufacture, produce, transfer, receive, acquire, or possess quantities of, or devices or equipment utilizing, radioactive material.