According to US Customs and Border Protection (CBP), “The mission of U.S. Customs and Border Protection (CBP) is to safeguard America’s borders – protecting the public from dangerous people and materials while enhancing the Nation’s global economic competitiveness by enabling legitimate trade and travel. To achieve this mission, CBP uses a layered enforcement strategy to monitor, regulate, and facilitate the flow of goods. A critical layer within this strategy is the use of Non-Intrusive Inspection (NII) systems and Radiation detection equipment (RDE), to detect and interdict contraband while facilitating the flow of commerce.”
What are customs officers engaged in radiation monitoring looking for? Many radiation sources are by their nature not dangerous. But the primary target really is what’s known as Special Nuclear Material (SNM), which can be used for assembling a nuclear weapon. Radioactive isotopes that, in consolidation, could be used by terrorists to make a dirty bomb include Plutonium, Uranium, and Neptunium (Pu, U, Np). That’s why it’s critical to know the exact isotope of the radioactive material in order to assess the potential threat.
The U.S. Nuclear Regulatory Commission (NRC) divides SNM into three main categories, according to the risk and potential for its direct use in a clandestine fissile explosive or for its use in the production of nuclear material for use in a fissile explosive. These categories are the following, with Category 1 being of highest concern. Category 2 materials, for example, are considered by The International Atomic Energy Agency (IAEA) as being able to cause permanent injury or even death in a person who comes in contact with them.
- Strategic SNM (SNM);
- SNM of moderate strategic significance; and
- SNM of low strategic significance. Understandably, sources registering indication as Strategic (SNM) materials are red-flag.
Over a million people a day are processed by the U.S. Customs and Border Protection at various borders where the latest radiation detection technology is utilized. How difficult it must be to move the crowd and quickly differentiate between a person who has had a radiation involved medical procedure, possibly triggering a detection alarm, and someone who is transporting some device or tool that has a potentially dangerous radiation source in it. (Legitimate radioactive sources must be licensed, and the carrier must have proof in documentation and declare it.)
The technology utilized by Personal Radiation Detectors can make these distinctions; this capability is known as NBR, or Natural Background Radiation discrimination. NBR is designed to save time and prevent false alarms by discriminating between a source of SNM material that might be hidden in a duffel bag, for example, and someone in a crowd who has had radiation treatment in a medical facility.
The Memorial Sloan Kettering Cancer Center notes that radioactive substances can indeed be emitted through body fluids such as saliva, urine, and sweat, for several days following certain procedures:
Doctors sometimes use small amounts of radioactive material to diagnose disease. This is called nuclear medicine. The radioactive substance is injected into your body, locating specific cells or tissues ― including cancer cells ― and binds to them. The radioactive material will stay in your body for several hours or days, depending on the type that is used. Eventually, the material decays and your body naturally flushes it out through urine, sweat, and other forms of biological elimination. We make sure the specifics are clear to you before the test, and we may also issue an information card explaining your treatment in case you are questioned by someone in airport security, for example.
Putting aside the medical issues, there are basically two types of situations with regard to radiation detection. In the first, somebody brings something in that they didn’t realize that they needed to register or check, an innocent mistake. Then there are the ones who are trying to deliberately smuggle radioactive material into the country for nefarious purposes. Take for example the Canadian border, a border passing through a lot of remote country, and probably even less closely guarded than the Mexican border. The more remote, the more likely that someone is going to try to smuggle something into the U.S. That’s simply because a terrorist, or someone with malicious intent, is rarely going to come through a normal checkpoint, where the odds are much in favor of being caught, but rather attempt to cross a border in a remote area, or come into the country through another adjacent country.
By providing significant detector sensitivity for search and find, combined with accurate high dose rate radiation measurement, the Personal Radiation Detectors with NBR technology can help identify the nature of the discovered material in a manner configurable for an operation or user skills – from simple artificial vs. natural distinction; to industrial, SNM, and medical classification; to full spectroscopic analysis.
For additional details, read: A new approach to border protection