ASNT

US NUCLEAR REGULATORY COMMISSION REGISTRATION

Table 10 Design and operational safety features in gamma radiography sources and devices

The US Nuclear Regulatory Commission (NRC) and its Agreement States perform engineering and radiation safety evaluations on the ability of sealed sources and devices to safely contain radioactivity under the conditions of their possession and use (Table 10). These evaluations are summarized in registrations that NRC maintains in the National Sealed Source and Device Registry System (NSSDRS). The registration certificates contain detailed information on the sources and devices, such as how they are permitted to be distributed and possessed (specific license, general license, or exempt), design and function, radiation safety, and limitations on use. Both the NRC and agreement states issue registration certificates for distributors and manufacturers within their jurisdiction. However, only the NRC is responsible for devices distributed as exempt products (such as smoke detectors and gun sights) and issues those registration certificates. The NRC’s regulations are found in Chapter I of Title 10 , Energy , of the Code of Federal Regulations (CFR). Chapter I is divided into Parts 1 through 199. Parts 34.20, 34.21, and 34.27 contain the require- ments most relevant to gamma radiography sources and devices. Each radiographic exposure device, source assembly, or sealed source—and all associated equipment—must meet the requirements specified in ANSI N432-1980: Radiological Safety for the Design and Construction of Apparatus for Gamma Radiography. This publication has been approved for incorporation by reference by the Director of the Federal Register in accordance with 5 U.S. Code 552(a) and 1 CFR Part 51. The following requirements apply to radiographic exposure devices, source changers, and sources. l The licensee shall ensure that each radiographic exposure device has attached to it a durable, legible, clearly visible label. l Radiographic exposure devices intended for use as Type-B transport containers must meet the applicable requirements of 10 CFR 71 .

Typical Sealed Source Materials

Source capsules

stainless steel, titanium, vanadium

Co-60 activity

metal pellet

metal disks/pellet, some clad in aluminum metal alloy/composite (elemental Se used outside the US) metal-oxide/glass-ceramic

Ir-192 activity

Se-75 activity

Yb-169 activity

Number of Encapsulations

Double or treble encapsulated

ISO/ANSI Source Integrity Minimum classification of C43515, typically higher is achieved. Special-form heat test and percussion test conditions are also met by Special-form sources; equivalent to C64515

Special Form

Co-60, Ir-192, Se-75

Yes

Yb-169

May sometimes be normal form capsules

Focal Spot Material and Shape

Ir-192

Metal cylinder

Co-60 Se-75 Se-75 Yb-169

Metal hemisphere Elemental cylinder

Metal-alloy quasi-sphere (vosoid) Oxide ceramic cylinder or sphere

Wire Mounting Crimped steel coupled to wire cable Tungsten back-shielded chain link

Emission Direction Link-style designs: side emission only (radial) Cable-style designs: end emission (axial) and side emission (radial) Leakage and Contamination Conformance to ISO 9978 , ANSI N432-1980 Endurance Source wear from repeated wind-outs and retractions based on application (ANSI requires 50 000 cycles, ISO requires 20 000 cycles)

CHAPTER 3

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Part 3