Back in the Day: Radiation Safety on the Submarine
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Back in the Day: Radiation Safety on the Submarine

By Dr. Zoomie

Dr. Zoomie – greetings from New York! And here’s my question. A few times you’ve mentioned being on a nuclear submarine and I was wondering if you can tell me how you guys stayed safe from radiation and all – I mean, you lived pretty close to a nuclear reactor for months at a time. Didn’t it cause problems for you?

Oh boy – here’s a chance to cavort down memory lane if there ever was one! And I guess I need to start by saying that I got out of the Navy in 1989 and their radiation safety practices might have changed since then – but here’s what we did back in the day. And I should say, too, that those of us who were responsible for radiation safety (the Navy called it RadCon, or Radiological Controls) were called Engineering Laboratory Technicians (or ELTs), and in addition to RadCon we also handled boiler water and reactor water chemistry controls.

Daily routine

A lot of our radcon occurred as part of our daily routine – the stuff we did every single day, usually on the Midwatch (midnight to 8 AM) as the Underway ELT. When I was Underway ELT I tried to structure my day so that I got most of the required work done on the Midwatch, so I’d wake up around 9 or 10 in the evening, I’d eat Midrats (the “meal” that was a sort of midnight snack), and then I’d start to work – first I’d initialize my instruments for the day by doing the daily checks (testing the response to radioactive sources, measuring background radiation, and so forth), then I’d draw and analyze my reactor coolant sample, and after that I’d do whatever radiation and contamination surveys were required. If reactor water chemistry was starting to change, as it often did if we were running at high speeds for prolonged periods of time, I’d also add chemicals to keep our pH in band or would take actions to reduce the amount of dissolved gases in the coolant. And we did radiation and contamination surveys every day (more about these in a moment), starting with a contamination survey of my nucleonics laboratory after each reactor coolant sample.

If I was efficient, I could polish off my daily routine by about 3 or 4 AM, then maybe stay up for breakfast and then do administrative work, training, and so forth until 3 or 4 in the afternoon, when I’d try to hit the rack until 10 or 11. If I was unlucky, I’d be woken up to do radiation surveys for entering tanks adjacent to the reactor compartment shield, to do contamination surveys if someone needed to do maintenance on our steam plant (just in case there was leakage from our reactor plant into the steam plant), or some other radiological task. When possible I tried to wrap up my day’s work on the Midwatch, but most days other stuff came up that kept me from getting a solid 6 hours or so of sleep.

Radiation surveys

We did a LOT of radiation surveys. When I drew the reactor water sample I did a radiation survey to see what sort of radiation levels I was working in and to see if our fuel might have suffered damage. Most days I did other radiation surveys, usually adjacent to the reactor compartment to make sure the shielding wasn’t damaged, and anytime we had to enter a tank or other space adjacent to the reactor compartment I’d do surveys to make sure whoever was making the entry was in a safe radiation field. In addition, there were routine radiation surveys that had to be performed regularly to make sure that nobody was being inadvertently exposed to radiation, maybe from a misplaced radioactive source, contamination, or a flaw in the shielding around the reactor compartment. And, speaking of the reactor compartment, if we needed to do work in the RC then I or whoever was the Duty ELT had to do an RC entry to perform a radiation survey so that anyone entering to do work would know where the hot spots were so they could plan their work better.

In addition to the interior surveys, if we were in-port I had to do some external surveys as well to make sure people on the pier weren’t getting too much radiation exposure. This was most important if we had no shore power and needed to keep the reactor running when we were tied up at the pier or anchored in the harbor.

Contamination surveys

We did a lot of contamination surveys too. Every day I’d survey my lab for contamination after analyzing the reactor coolant sample, as well as checking the area around the reactor coolant sample sink in case some coolant had splashed when I was taking our sample. On top of that, I’d check the path I’d walked from the reactor coolant sample sink to my lab to make sure I hadn’t spread contamination when walking from the sink to the lab. Every month I also did contamination survey of the entire submarine – one area each week – just to make sure contamination hadn’t been deposited elsewhere accidentally.

The contamination surveys could take a couple of different forms – I could do a “frisk” by moving a radiation detector over the floor, counter, or whatever surface was being surveyed or I could wipe a small piece of filter paper over the counter of floor (or whatever) and then hold that under a Geiger counter to see if it had picked up any contamination.

Radiation dosimetry

We issued radiation dosimeters to everyone onboard who work with or around radiation. This included all of the “nukes” – the guys who worked on the reactor and propulsion plants – as well as any of the non-nukes who worked adjacent to the reactor compartment or who might work with nuclear weapons that we might (or might not) have onboard.

In addition to the routine monthly dosimetry reads we would do special reads for anyone who entered the reactor compartment or any other areas with elevated radiation levels. So if I, for example, entered the reactor compartment to do a survey then I’d read my dosimeter (and that of anyone else who made an entry with me) to see how much radiation I’d picked up during the entry.

The goal of all of this was to make sure that nobody exceeded a radiation dose limit as well as to try to keep our radiation exposures as low as reasonably achieve able (ALARA).  More on this shortly!


The goal of all of this was to keep radiation exposure to everyone onboard as low as reasonably achievable (ALARA). ALARA is the guiding philosophy for radiation safety around the world. ALARA might be the guiding philosophy for radiation safety – but it’s also frequently misunderstood. ALARA does not mean trying to keep radiation exposure as low we can possibly keep it, it means keeping them as low as we can reasonably keep them. If some action makes it quick, easy, or cheap to reduce radiation exposure then we ought to consider it. But if it will cost a lot of money or require a great effort to reduce radiation exposure by just a little bit then the saved exposure might not be worth the effort.

 And here’s a great example of that – there was one time when shipyard workers were going to be working in the vicinity of a piece of equipment that gave off elevated levels of radiation – certainly not dangerous, but high enough so that the shipyard would have had to pay their workers an additional bonus for working in an area with higher levels of radiation. So the shipyard insisted that we install temporary radiation shielding around the piece of equipment to reduce rad levels to the point where they didn’t have to pay the high-rad bonus rate. And, sure, looking at how much the dose was reduced, the total dose to the shipyard workers was cut nearly in half, reducing their total exposure by about 1 rem, summed across all of the workers. The thing is, we had to install the shielding, meaning we were exposed to the unshielded radiation, and it’s not easy to bend lead sheets around an irregularly shaped piece of equipment and to secure them with metal bands, using an awkward tool. In order to reduce dose to shipyard workers by about 1 rem, me and my fellow “nukes” absorbed a cumulative 1.5 rem of additional dose. In other words, the total person-rem (dose among all persons) was increased in order to save the shipyard some money. Reducing their exposure worked out well for the shipyard – but is was not reasonable to reduce their exposure at the expense of the ship’s crew.

Water and air sampling

Another part of our radiation safety program was performing routine checks for radioactivity in the atmosphere as well as in our drinking water and other fluid systems. We did the air sampling because the reactor plant was at a high pressure and we wanted to make sure the reactor coolant wasn’t leaking into the atmosphere or into the steam plant (the reactor and steam systems were physically separate) – if even a tiny leak developed we’d see reactor coolant contaminating the atmosphere. Even leaks into the steam system would end up in the atmosphere because there were always small amounts of steam escaping into the atmosphere. So we had several machines that continuously sampled the air in various parts of the engineering spaces, and under some circumstances we’d use a portable air sampler to pull a cubic meter of air through a piece of filter paper that was then counted using a Geiger counter to see if there was any radioactivity on it. If an air sample ever came up “hot” then we’d all put on respirators until we could sort things out – that might mean coming shallow to ventilate the boat, finding and stopping a leak, or maybe simply realizing we’d had a false alarm.

We also needed to perform occasional checks of our fresh water to make sure no radioactivity had got into any of them. Some of these tanks held drinking water, others held fresh water used to cool things like our main coolant pumps, which could not be cooled using seawater (which is corrosive and filled with minerals that could become radioactive when exposed to neutrons from fission), and still others used to store water we could add to the steam plant or reactor plant to make up for trace leaks or water removed for sampling. These were all sampled regularly – during my time onboard we never had any air or water samples that came up hot except for a few spurious alarms.

My favorite survey!

Radiation surveys are usually not a lot of fun – they can be time-consuming, there’s the need to record the readings precisely, and you rarely find anything unusual, so they’re usually not very interesting. But there was one survey I loved performing and I volunteered for it every time – surveying topside when we pulled into port.

The reason we did this survey was to look for contamination – we sometimes discharged reactor coolant overboard and, even though we ran it through filters and an ion exchanger, there was still the chance that it contained some radioactivity. So we checked the hull for contamination when pulling into port. In fact, we had to do this survey before anyone was allowed to go topside, with the exception of the person performing the survey and a diver (in case I fell overboard).

The first time I did the topside survey was when we were pulling into port in Japan after two months at sea. After two months of breathing fetid air, reading by fluorescent lights, seeing mostly gray, red, and white, and continually surrounded by my shipmates I was suddenly topside on a warm and sunny day, breathing the fresh air; I was so enraptured by it all that I momentarily forgot why I was up there. Then I remembered and sort-of got to work, dragging the process out as long as I could as we made our way into Tokyo Bay. At other times I performed this survey in the tropics as we pulled into ports in Hawaii, Guam, and the Philippines; looking at snowy mountains in the Aleutian Islands or the somewhat more cosmopolitan mountains in Hong Kong, on a chilly spring day in South Korea, and four times pulling into port in San Diego after prolonged absences. After the survey, though, it was time to pop back down the hatch, check the wipes for contamination, and then get back to the business of shutting down the reactor.