(c) Not more than 300 curies of solid cesium 137, cobalt 60 or iridium 192, may be packed in one outside container for shipment by rail freight, rail express, or highway, except by special arrangements and under conditions approved by the Bureau of Explosives.* Within the AEC, activities of shipments of all radioactive materials generally are measured in curies or in sub-multiples of curies. One curie is equivalent to 1,000 millicuries or to 1,000,000 microcuries. From Note 1 above, "that amount of any other radioactive substance which disintegrates at the rate of 100,000 million atoms per second" is 2.7 curies.

Paragraph 73.391 (b)* is generally interpreted as permitting the shipment of 2 curies (2 grams) of Ra226 in a single package, regardless of the fact that, as ordinarily shipped, the package would contain approximately two curies each of a number of radioactive decay products. That this was the intent of the National Research Council subcommittee formulating the original draft of these regulations, is indicated by the following statement from page 39 of NRC Publication 205: "The maximum quantity of radium whose shipment is permitted in a single container, as in a neutron source, is 2000 mc. or 2 gm. Ra.” Field comment indicates, however, that some AEC installations interpret the two curies as applying to all of the radioactive material believed to be in the package. The latter interpretation receives some support from 73.27 (6). The interpretation of this paragraph as applied to other radioactive substances, e. g., uranium, thorium, strontium 90, zirconium 95, is also controversial.

73.392. Exemptions for radioactive materials:

(a) Radioactive materials are exempt from prescribed packaging, marking and labeling requirements provided they fulfill all of the following conditions:

1) The package must be such that there can be no leakage of radioactive material under conditions normally incident to transportation.

2) The package must contain not more than 0.1 millicuries of radium, or polonium, or that amount of strontium 89, strontium 90, or barium 140 which disintegrates at a rate of more than 5 million atoms per second; or that amount of any other radioactive substance which disintegrates at a rate of more than 50 million atoms per second.

That amount of material which disintegrates at the rate of 5 million atoms per second is 0.135 millicuries; and that which disintegrates at the rate of 50 million atoms per second is 1.35 millicuries.

3) The package must be such that no significant alpha, beta, or neutron radiation is emitted from the exterior of the package and *Revised May 3, 1955.

the gamma radiation at any surface of the package must be less 10 milliroentgens for 24 hours.

(b) Manufactured articles other than liquids, such as instrument or clock dials or electronic tubes and apparatus, of which radioactive materials are a component part, and luminous compounds, when securely packed in strong outside containers are exempt from specification packaging, marking, and labeling requirements provided the gamma radiation at any surface of the package is less than 10 milliroentgens in 24 hours.

1) Switchboard or similar apparatus containing electronic tubes, of which radioactive materials are a component part, are exempt from specification packaging, marking, and labeling requirements when shipped in carload or truckload lots or when transported by private motor carrier provided the gamma radiation at any readily accessible surface of the units, when prepared for shipment, does not exceed 50 milliroentgens in 24 hours.*

(c) Radioactive materials such as ores, residues, etc., of low activity packed in strong tight containers are exempt from specifications packaging and labeling requirements for shipment in carload lots by rail freight only provided the gamma radiation or equivalent will not exceed 10 milliroentgens per hour at a distance of 12 feet from any surface of the car and that the gamma radiation or equivalent will not exceed 10 milliroentgens per hour at a distance of 5 feet from either end surface of the car. There must be no loose radioactive material in the car, and the shipment must be braced so as to prevent leakage or shift of lading under conditions normally incident to transportation. The car must be placarded by the shipper as provided in 74.541 (b) and 74.553. Shipments must be loaded by consignor, and unloaded by consignee.

Paragraph 73.392 (c) provided exemption from specification packaging, marking and labeling for shipments of packaged low activity materials by rail freight, in carload lots only, subject to the conditions given therein. Such exemption is provided independently of the general conditions for exemption from specification packaging, marking and labeling given in paragraph 73.392 (a). However, such materials are not exempt from specification packaging, labeling and marking when shipped by motor truck or by railway express unless they meet the requirements of 73.392 (a). See, for example, 77.815 (a), (b), and (c).

The term "low activity material" is not defined by the ICC. The wording of 73.392 (c) and of 74.532 (j) (1) implies that any gamma emitting material, a full carload of which does not produce radiation in excess of 10 mr./hr. at a distance of 12 feet from any surface of the car may be considered low activity material for this purpose.

*Revised May 3, 1955.

Limitation of the radiation from either end of the car to 10 mr./hr. at 5 feet may be achieved either by spacing or by the use of shielding. The term "no loose material" is not defined by the ICC. The usage here and in paragraph 74.532 (j) implies that "loose material" means amounts of material which may be introduced as a result of spillage, either within the car or onto the containers or equipment which are brought into the car. The level of gamma radiation which may exist in the car after unloading is specified in section 73.395.

73.393. Packing and shielding:

(a) Radioactive materials that present special hazards due to their tendency to remain fixed in the human body for long periods of time (i. e., radium, plutonium, and radioactive strontium, etc.) must, in addition to the packaging hereinafter prescribed, be packed in inside metal containers specification 2R, or other container approved by the Bureau of Explosives.

Specifications for 2R containers are given in Section 78.34 of the ICC Regulations (not excerpted in this Handbook). The requirement that packages containing radium, plutonium, etc., be packed in inside containers of this specification is not considered to apply to cases in which these radioisotopes occur in low activity materials as discussed in 73.392 (c) or as impurities in other radioactive materials.

(b) All radioactive materials must be so packed and shielded that the degree of fogging of undeveloped film under conditions normally incident to transportation (24 hours at 15 feet from the package) will not exceed that produced by 11.5 milliroentgens of penetrating gamma rays of radium filtered by 1/2 inch of lead.

The quantity of gamma radiation referred to, 11.5 milliroentgens, is that measured after filtration by the lead. Photographic emulsions are more sensitive to gamma radiations of quantum energies less than about 0.15 Mev than to harder or more penetrating gamma radiation of higher quantum energies. Filtration of radium gamma radiation by this thickness of lead removes practically all of the quanta with energies as low as 0.15 Mev and provides an arbitrary standard of photographic effectiveness with which other gamma radiation may be compared.

For cases in which the gamma emission from the radioactive materials within the package contains a strong component of quantum energy higher than about 0.2 or 0.3 Mev, and a substantial amount of lead shielding is used in bringing the radiation from the package down to prescribed limits, the gamma radiation emitted from the package may be considered to have the same photographic effectiveness per milliroentgen of exposure as gamma radiation from radium filtered by 1/2 inch of lead. Ordinarily, for Group I packages, this is the case.

The following table, adapted from Table IX, p. 48, NRC Publication 205 (cited in Chapter I of this Handbook), gives the relative sensitivity of photographic emulsions to gamma radiations of different quantum energies below 0.15 Mev as compared to sensitivity to radium radiation filtered as specified above:

Quantum energy-
Relative sensitivity.

0.14 0.12 0.09 0.075
1.2 2.3 4.9 8.6 14

0.06

0.045 0.03 21

24

As an example of the application of these values to paragraph 73.393(b), if a package emits gamma radiation of which the effective quantum energy is 0.09 Mev, the maximum gamma radiation permitted at 15 feet from the package is 11.5/4.9 milliroentgens per 24 hours. For a more complete discussion, the reader is referred to NRC Publication 205, pp. 15-24 and 48-49.

(c) The design and preparation of the package must be such that there will be no significant radioactive surface contamination of any part of the container.

(d) The smallest dimension of any outside shipping container for radioactive materials must be not less than 4 inches.

(e) All outside shipping containers must be of such design that the gamma radiation will not exceed 200 milliroentgens per hour or equivalent at any point of readily accessible surface. Containers must be equipped with handles and protective devices when necessary in order to satisfy this requirement.

(f) The outside shipping container for any radioactive material, unless specifically exempt by 73.392 or unless approved by the Bureau of Explosives, shall be as follows: (1) Spec. 15A or 15B (78.168 or 78.169 of this chapter). Wooden boxes. Authorized for not more than 2,700 millicuries; (2) Spec. 12B (78.205 of this chapter). Fibreboard boxes. Authorized for not more than 2,700 millicuries; (3) Spec. 21A or 21B (78.222 or 78.223 of this chapter). Fibre drums. Authorized for not more than 2,700 millicuries; (4) Spec. 6A, 6B, or 6C. 17C or 17H (single-trip) (78.97, 78.98, 78.99, 78.115 or 78.118 of this chapter). Metal barrels or drums. Authorized for not more than 2,700 millicuries; (5) Spec. 55′ (78.250 of this chapter). Metal-encased, lead-shielded containers. Authorized for not more than 300 curies (see 73.391). Containers must be equipped with a seal.*

Specifications for these containers are given in Part 78 of ICC regulations. These specifications are not excerpted in this Handbook.*

(g) Radioactive materials Group I, liquid, solid, or gaseous, must be packed in suitable inside containers completely surrounded by a shield of lead or other suitable material of such thickness that at any time during transportation the gamma radiation at one meter *Revised May 3, 1955.

(39.3 inches) from any point on the radioactive source will not exceed 10 milliroentgens per hour. The shield must be so designed that it will not open or break under conditions incident to transportation. The minimum shielding must be sufficient to prevent the escape of any primary corpuscular radiation to the exterior of the outside shipping container.

“. . . at one meter from any point on the radioactive source is interpreted to mean "at one meter from the nearest point on the source."

(h) Radioactive materials Group II, liquid, solid, or gaseous, must be packed in suitable inside containers, completely shielded so that at any time during transportation the radiation measured at right angles to any point on the long axis of the shipping container will not exceed the limits specified in subparagraphs (1) to (4) of this paragraph. The shielding must be designed so as to maintain its efficiency under conditions normally incident to transportation and must provide personnel protection against fast or slow neutrons and all other ionizing radiation originating in the radioactive materials or any part of the aggregate constituting the complete package.

(1) Gamma radiation of 10 mrhm.

(2) Electrically charged corpuscular radiation which is the physical equivalent (see note 1 of this paragraph) of 10 mrhm. of gamma radiation.

(3) Neutron radiation which is the physical equivalent (see note 1 of this paragraph) of 2 mrhm. of gamma radiation.

(4) If more than one of the types of radiation named in subparagraphs (1), (2), and/or (3) of this paragraph is present the radiation of each type must be reduced by shielding so that the total does not exceed the equivalent of subparagraphs (1), (2), or (3) of this paragraph.

NOTE 1.-For purposes of Parts 71-78 the "physical equivalent" of a roentgen is that amount of radiation that would be absorbed in tissue to the extent of 100 ergs per gram (mrhm. is an abbreviation for milliroentgens per hour at 1 meter (39.3 inches)).*

(i) Liquid radioactive materials Groups I, II or III must, in addition, be packed in tight glass, earthenware, or other suitable inside containers. The inside containers must be surrounded on all sides and within the shield by an absorbent material sufficient to absorb the entire liquid contents and of such nature that its efficiency will not be impaired by chemical reaction with the contents. If the container is packed in a metal container specification 2R or other container approved by the Bureau of Explosives, the absorbent cushioning is not required.

*Revised May 3, 1955.

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