Radioactive Materials Security – What is IC Quantity?
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Radioactive Materials Security – What is IC Quantity?

By Dr. Zoomie

Hi, Dr. Zoomie – I am putting together a radioactive materials license and they’re asking me what sort of security I have and whether or not I have an “IC quantity” of radionuclides. To be honest with you, I’m not sure what an “IC quantity” is, and I’m also not sure how much security I need. Help!

OK – so let’s try to get this sorted out for you, and it shouldn’t be too bad (hopefully)!

First let’s tackle the easy one. “IC” stands for Increased Controls – a concept that came out within the last decade or so (the new security regulations are only a year or so old). That’s the amount of radioactivity that calls for higher levels of security. If you have less than the IC quantity then you don’t have to worry; more than the IC quantity and security becomes a bigger issue. IC quantities are listed in 10 CFR 37 – for Cs-137 for example the IC quantity is 27 curies; as long as you have less than 27 Ci of Cs-137 on your license then you don’t have to worry about the added IC precautions.

Let’s say you have three nuclides (A, B, and C) and the IC limit is 10 Ci for nuclide A, 20 Ci for nuclide B, and 30 Ci for nuclide C. What you have on hand is 6 Ci of nuclide A, 10 Ci for nuclide B, and 6 Ci of nuclide C. You don’t have an IC quantity of any single nuclide – are you off the hook? Sadly no, and it’s because of the sum of fractions rule. 6 Ci of nuclide A is 60% of the IC limit for that nuclide, 10 Ci of nuclide B is 50% of the limit for it, and 6 Ci of nuclide C is 20% of that limit. If you add these up (0.6+0.5+0.2) you come out with 1.3 – if the sum of the fractions is less than 1.0 then you’re OK; since you come in above that level then IC applies to you (sorry).

OK – so that’s what IC means and when you have to use it; now let’s get into the harder question about how to secure your materials.

The bottom line is that, no matter how much (or how little) radionuclide you have on hand, you need to make sure that nobody can steal it and that nobody can accidentally be exposed to enough radiation to hurt them. The less risk a source poses the less security you need to have. But no matter how minor a source, you are required to take steps to make sure that nobody can just come in off the street and take your radioactive materials without being stopped.

Fiber Optic Active Seal Installation
Fiber Optic Active Seal

So – say all you have is a soil density (“nuclear”) gauge, a lead paint analyzer, or a tank level gauge. The portable devices (lead paint analyzer and soil density gauge) are going to have to be kept locked up at all times. In your office they will have to be kept in a locked room, preferably in a locked cabinet or safe inside that room for added security. Better yet is to limit access to the room to only those people who are permitted to use the source. But the bottom line is that you have to do what you can to keep it from being stolen. In the field, by the way, this means keeping a device locked into the trunk of a car or in a toolbox that locks and that’s fastened to your van or pickup truck.

If you have a higher-activity source or a combination of sources that call under the IC regimen then you’ve got even more work to do. In addition to seeing to the physical security of the source you’re going to have to work with your on-site security or with a security contractor because you’re going to have to submit fingerprints of all the workers who will have access to the source, conduct a background check, and make sure that they are considered to be trustworthy and reliable. If they don’t pass the background check, if they refuse to be fingerprinted, or if their fingerprints have shown up somewhere that they shouldn’t then you probably won’t be able to give that person access to your higher-activity sources.

There are a lot of other aspects to the IC program – you should really check out 10 CFR 37 for all the details – but these are what seem to trip people up the most.

A few other things to keep in mind, with any level of radioactive materials. One is that keys are a weak point of many security systems because they can be copied, lost, or taken with a departing worker. It is far better to have keycard access or, at least, a numeric keypad to gain access to a room. If a key is compromised then you have to call a locksmith and issue new keys to everyone with access to a particular room. On the other hand, if a disgruntled employee leaves your company all you have to do is to revoke authorization for his keycard, or change the key code – much easier and less expensive.

The other thing to remember is that it’s hard to defend against an insider who has legitimate access to a radioactive source. This could be a disgruntled employee, someone who’s looking for quick cash, or a criminal who managed to make it past your background check. But it could also be a loyal employee who is being threatened or who is under substantial pressure. The bottom line is that anyone who has legitimate access to your radioactive sources has the potential to become a weak point in your security program – this is one good reason to conduct periodic evaluations of a person’s reliability to try to make sure they haven’t become a threat since their last check.

Finally, you should consider going beyond the bare minimum required by the regs. Consider asking your local police precinct to visit your facility and take a look at your physical security – they might see things that you would miss. You might want to put in cameras at critical doors to keep track of who’s entering and leaving secured rooms, and you might even consider thermal or motion detectors in your most sensitive spaces. Don’t use flimsy doors (and especially not doors with windows in them) to safeguard high-activity sources, don’t store them near (or in) a loading dock area, and so forth. Let’s face it – in addition to the cost of the sources themselves, a terrorist attack can cause a huge economic impact on your community – you (and your company) don’t want that to come from one of your sources. This is another good reason to ask a professional to evaluate your facility and make recommendations – and for you to follow those recommendations.

Good luck!