Preparing for nuclear war - Launching my radiation monitoring station

Today is Remembrance Day. The day when we're meant to celebrate the end of the first world war and to remember those killed and maimed in that conflict. The message was meant to be that even at best war is a necessary evil, but it is always an evil and we need to exert ourselves to prevent it from happening again.

Subsequent history has shown how well that message has been taken on board, and today I celebrate this date by publicly launching my Radiation Monitoring Station in anticipation of a possible nuclear conflict.

You can view radiation readings from the station at this link

The Radiation Monitoring Station

Background

As of this year, the Doomsday Clock is now at 2 1/2 minutes to midnight. This is the closest it's been in my lifetime, and I am in my 50's. In fact it has only once been closer: in 1953 it was at 2 minutes to midnight.

For some reason, it appears that no one in power cares much about this. By contrast, "terrorists" (who don't actually exist in this country), are seen as such an immediate and terrifying threat that laws giving the police more and more extra powers are rushed through parliament so frequently that it's difficult to keep track of them. Recently new legislation was passed in Queensland allowing police to search people and vehicles without a warrant and install malware on people's computers. All that is needed to invoke these powers is that "the emergency commander is satisfied on reasonable grounds" that certain very broadly defined conditions - not necessarily involving an actual terrorist attack [why am I not surprised?] - exist.

Anyway, enough of the political rant. I believe that, while still unlikely, the chance of a bomb going off somewhere, probably through accident or stupidity rather than by deliberate intent, is non-negligible. Were this to happen, a big question in this part of the world would be about fallout: where and how much and what sort of threat exists.

Now Australia does not, to my knowledge, have any sort of official radiation monitoring network. There is some sort of monitoring near the Lucas Heights reactor and most probably the physics departments of various universities have capabilities in this area, but we have nothing approaching the EPA's RadNet network. A disaster would therefore catch us flat-footed and the government would naturally default to "Keep Calm and Carry On" mode and concentrate on deflecting the blame it would receive for not having anticipated this problem. With a vacuum of official information, the mainstream media would report all sorts of ill-informed speculation as fact. Even the alternative media - usually more reliable than the mainstream - could not be trusted in the situation.

Therefore I decided to build my own monitoring station. That way I could at least get information that, if not as accurate as that from a professionally built station, was at least trustworthy (in the sense of being under my personal control) and relevant to my exact location.

Some Technical Details

The station currently consists of two nominally identical Geiger counters. This is mainly for redundancy in case one fails, however, when both are working, the counts from both counters are combined to give higher resolution.

Each counter contains five SI-22G tubes and one SI-3BG tube. For reference, this is what they look like. I've included an SBM-20 tube (probably the most popular tube used by amateur experimenters) for comparison.

Some Soviet Geiger tubes

These tubes were all produced in the Soviet Union in the 1970's and 80's and were purchased from a Ukrainian seller on eBay. Despite their age, all of these tubes work correctly.

The SI-22G's are highly sensitive tubes and by combining ten of them, it's possible to detect relatively small changes in background radiation. When the rate is averaged over an hour these tubes can detect a change in background level of +/- 1.5%. Greater resolution can be achieved by averaging over a longer period, although this comes with the penalty of a slower response. [There is actually some interesting (to some) mathematics in determining the resolution of Geiger tubes - it's fundamentally different to measuring other quantities like temperature and pressure because it inherently varies randomly - but I won't go into this here.]

The SI-3BG tube is my "nuclear war" tube. The issue is that high levels of radiation will overwhelm the SI-22Gs; beyond a certain point they actually start to count less the higher the radiation gets; an effect called fold-back. This is obviously a very bad thing. Now it's unlikely we would get such levels in this part of the world, but it just feels wrong to knowingly design a radiation monitoring station that will fall over in the very situation when it would be needed the most - even if that situation is highly unlikely to ever occur.

Hence the SI-3BG tube. This tube was used as the high-range tube in Soviet military Geiger counters, which measure up to 200 R/h; a level which would be fatal after a couple of hours exposure. This is almost 20,000,000 times background level and something you'd only get if you were in the direct path of fallout. The rest of the monitoring system will fail before this tube gets overloaded.

The circuit driving the tubes is based on the Theremino Geiger Adaptor. This is a simple, yet stable and efficient design. In general, the design shows evidence of being much better thought out than most other designs on the web.

Geiger Counter 2 circuitry (No. 1 is slightly different in layout but fundamentally the same)

I adapted this design in a number of ways, but I will resist the temptation to go into any more detail at the moment. I should probably make a post dedicated to this at some time.

More Information

I have put an FAQ page on the site which goes into more detail about the station and radiation monitoring in general.