As used in these regulations, each of the following terms
shall have the meaning specified in this regulation:
(a)"NARM" means any naturally occurring or
accelerator-produced radioactive material, not including by-product, source, or
special nuclear material.
(b)"Nationally tracked source" means a sealed
source containing any quantity of radioactive material equal to or greater than
any threshold listed in the table in this subsection. For purposes of the
definition of nationally tracked source," sealed source" shall be defined as
radioactive material that is sealed in a capsule or closely bonded, that is in
a solid form, and that is not exempt from regulatory control. For purposes of
the definition of"nationally tracked source,""sealed source" shall not include
any radioactive material encapsulated solely for disposal and any nuclear
material contained in any fuel assembly, subassembly, fuel rod, or fuel pellet.
Category I nationally tracked sources contain radioactive material in
quantities equal to or greater than the category 1 threshold. Category 2
nationally tracked sources contain radioactive material in quantities equal to
or greater than the category 2 threshold but less than the category 1
threshold.
Nationally tracked source thresholds
|
Radioactive material
|
Category 1 (TBq)*
|
Category 1 (Ci)**
|
Category 2 (TBq)*
|
Category 2 (Ci)**
|
|
Actinium-227
|
20
|
540
|
0.2
|
5.4
|
|
Americium-241
|
60
|
1,600
|
0.6
|
16
|
|
Americium-241/Be
|
60
|
1,600
|
0.6
|
16
|
|
Californium-252
|
20
|
540
|
0.2
|
5.4
|
|
Cobalt-60
|
30
|
810
|
0.3
|
8.1
|
|
Curium-244
|
50
|
1,400
|
0.5
|
14
|
|
Cesium-137
|
100
|
2,700
|
1
|
27
|
|
Gadolinium-153
|
1,000
|
27,000
|
10
|
270
|
|
Iridium-192
|
80
|
2,200
|
0.8
|
22
|
|
Plutonium-238
|
60
|
1,600
|
0.6
|
16
|
|
Plutonium-239/Be
|
60
|
1,600
|
0.6
|
16
|
|
Polonium-210
|
60
|
1,600
|
0.6
|
16
|
|
Promethium-147
|
40,000
|
1,100,000
|
400
|
11,000
|
|
Radium-226
|
40
|
1,100
|
0.4
|
11
|
|
Selenium-75
|
200
|
5,400
|
2
|
54
|
|
Strontium-90
|
1,000
|
27,000
|
10
|
270
|
|
Thorium-228
|
20
|
540
|
0.2
|
5.4
|
|
Thorium-229
|
20
|
540
|
0.2
|
5.4
|
|
Thulium-170
|
20,000
|
540,000
|
200
|
5,400
|
|
Ytterbium-169
|
300
|
8,100
|
3
|
81
|
* The Terabecquerel (TBq) values are the regulatory
standard.
** The curie (Ci) values specified are obtained by converting
from the TBq value. The curie values are provided for practical usefulness and
are rounded after conversion.
(c)"Natural radioactivity" means the
radioactivity of naturally occurring nuclides.
(d)"Non-fixed contamination" means
contamination that can be removed from a surface during normal conditions of
transport.
(e)"Nonionizing
radiation" means radiation not capable of producing ionization, including sound
and radio waves and visible, infrared, or ultraviolet light.
(f)"Non-stochastic effect" means a health
effect, the severity of which varies with the dose and for which a threshold is
believed to exist. For purposes of these regulations,"deterministic effect"
shall be considered an equivalent term.
(g)"Normal operating procedures" means
operating procedures for conditions suitable for routine purposes with
shielding and barriers in place, including routine alignment procedures. This
term shall not include maintenance procedures and routine and emergency
radiation safety considerations.
(h)"Normal treatment distance" means either
of the following:
(1) For electron
irradiation, the distance from the virtual source to the surface along the
central axis of the useful beam, as specified by the manufacturer; or
(2) for X-ray irradiation, the distance from
the virtual source to the isocenter along the central axis of the useful beam.
For non-isocentric equipment, this distance shall be the distance specified by
the manufacturer.
(i)"Nuclear regulatory commission,""NRC," and
commission" mean the U.S. nuclear regulatory commission or its authorized
representatives.
(j)"NVLAP" means
the national voluntary laboratory accreditation program.
