CATEGORY 1 QUANTITIES - COMMON APPLICATIONS

Gamma Irradiation: Sterilizes medical supplies/equipment to prevent 

the spread of disease. Medical product is irradiated in its final 

container, assuring product is sterile untilopened.

Typically 24/7 operations. FDA and NRC approved.

Co-60 – typical facility has 500-600 pencils - 7,000-11,000 Ci each

Food Irradiation: Food, spices, and drink containers are sterilized to 

improve food safety; prevent illnesses, outbreaks, recalls; extend 

shelf life; kill insects. Leaves no chemical residues on product.

FDA and NRCapproved.

Co-60 – typically facility has 500-600 pencils - 7,000-11,000 Ci each

Cancer Treatment: External Beam Radiation Therapy or Stereotactic 

Radiosurgery (e.g., GammaKnife®), radioactive material used to kill 

cancerous tissue and reduce tumor size. Reaches inoperable areas of 

the brain and spine. FDA and NRCapproved.

Co-60 – typically 201 sources per device – 30 Ci each

Agriculture: Sterile insect technique, used in agricultural 

applications to control insect populations that threaten livestock, 

fruit, vegetables and fiber crops. Sterile insects do notbreed.

USDA and NRC approved.

Co-60 or Cs-137 – depends on facility size – multiple sources up to 

50,000 Ci total

Blood Supply: Blood irradiators, irradiate blood for immunoincompetent or immuno-compromised patients to prevent GraftVersus-Host Disease, which is fatal. FDA and NRC approved.

Cs-137 –devices can range from 600 – 3,000 Ci (depends on facility 

throughput needs)

Research: Research irradiators, used to expose biologic and nonbiologic materials to radiation to evaluate the response of the target 

materials. Also used to evaluate electronic and satellite components. 

Typically used at educational and medical institutions.

NRC approved.

Co-60 or Cs-137– devices can range from 400 – 3,000 Ci

Power Source: Radioisotope Thermoelectric Generator (RTG), used 

as a power source for unmanned remote arctic facilities, and in space 

applications. In the U.S., RTGs using Sr-90 are only used by the DOD, 

those using Pu-238 are used byNASA.

Sr-90 – RTGs range from 50,000 Ci to 200,000 Ci

Cancer Treatments: Globally, teletherapy devices are used to deliver 

an external source of radiation to treat deep seated cancerous 

tumors. Teletherapy (human) has been replaced by linear accelerator 

(LINAC) devices in the U.S. A few units exist in the U.S., typically used 

for veterinary applications.

Co-60 or Cs-137 – devices can contain up to 10,000 Ci
CATEGORY 2 QUANTITIES - COMMON APPLICATIONS

Fixed Radiography: Nondestructive testing method for inspecting 

materials for hidden flaws. Similar to how X-ray technology is 

used to check for broken bones. On portable specimens, 

radiography is conducted within a shielded vault at a fixed facility.

Ir-192 ~ 100-150 Ci per device, Co-60 ~ 100-300 Ci per device

Portable Radiography: Nondestructive testing method for 

inspecting materials for hidden flaws. Portable radiography devices 

are used to verify structural integrity in a wide variety of field 

conditions, e.g. pipelines, buildings, tanks, oil platforms,etc.

Ir-192 ~ 100 -150 Ci per device, Co-60 ~ 100-300 Ci per device 

Se-75 ~ 150 Ci per device, Yb-169 up to 81 Ci (category 3)

Calibrator: This device uses radiation sources of a known intensity 

for calibration of radiationmonitoring equipment and dosimeters.

Co-60 – up to 200 Ci per device

Cs-137 – up to 20 Ci per device

CATEGORY 3 QUANTITES – COMMON APPLICATIONS

Cancer Treatments: High-dose rate brachytherapy is a type of 

internal radiation therapy that delivers radiation from implants 

placed close to or inside the tumors in the body through a catheter. 

At the end of the treatment cycle, the sources are retracted back into 

the device or remain in the patient.

Ir- 192 – multiple sources up to 14 Ci total

Petroleum Industry: A well-logging source, measures hydrogen levels 

in rock strata around the bore hole of an oil well by backscatter 

measurement. This measurement, combined with others, give an 

indication of the presence of hydrocarbons.

Am/Be – typically ~15.8 Ci

Production Lines: A radioactive measuring system to determine: the 

level or transmission in a tank or line; the backscatter of a beam of 

radiation passing through a thickness; or the amount of water in a 

material passing through a system.

Cs-137 ~ 10 Ci, Co-60 ~1 Ci, Am/Be ~3 Ci

Pacemaker: Around 1979, pacemakers were designed with a Pu 

based battery. These pacemakers were soon obsolete and replaced 

by the development of lithium battery based pacemakers. A very 

small population of patients with this pacemaker are still alive. Upon 

death, the pacemaker is removed from the patient anddisposed.

Pu – pacemaker typically contained 3 Ci
Radionuclide

Category 1, 2, and 3 Thresholds

NRC - 10 CFR Part 37

and Parts 20, 30-36, and 39, as appropriate

NRC - 10 CFR Part 20

and Parts 30-36, 39 

as appropriate

Cat 1 Cat 2 Cat 3 (and lower)

TBq Ci TBq Ci TBq Ci

Am-241 (Be) 60 1,620 0.6 16 .2 0.0006 1.6

Cf-252 20 540 0.2 5.40 0.0002 0.5

Cm-244 50 1,350 0.5 13.5 0.0005 1.4

Co-60 30 810 0.3 8.10 0.0003 0.8

Cs-137 100 2,700 1 27.0 0.001 2.7

Gd-153 1,000 27,000 10 270 1.00 27

Ir-192 80 2,160 0.8 21.6 0.08 2.2

Pm-147 40,000 1,080,000 400 10,800 40.00 1,080

Pu-238 60 1,600 0.6 16.2 0.06 1.6

Pu-239 (Be) 60 1,600 0.6 16.2 0.06 1.6

Ra-226 40 1,080 0.4 10.8 0.04 1.1

Se-75 200 5,400 2 54.0 0.20 5.4

Sr-90 (Y-90) 1000 27,000 10 270 1.0 27

Tm-170 20,000 540,000 200 5,400 20.00 540

Yb-169 300 8,100 3 81.0 0.30 8.1

All other radioactive 

materials