yet another Cornish Station

[PolwinDave]

Hi All,
Just got a wh1090 & Cumulus set up here so still learning. Took me a while to suss the reset of the rainfall data after I got the rain gauge out of the wind - Although I changed the data files, it took an 'end of met day period' before I understood what was happening. Think I've got it now

Have been looking at radon levels hereabouts (just 1m W of Falmouth in the valley of Budock Water) and trying to tie radon in with weather. Culdrose data - abt 10 miles away showed no significant associations with weather except severe wind events, so i wanted to test out the extremely local situation here. Is anyone else monitoring radon levels?

Thanks Steve for a great piece of software.
Regards
Dave

[Repairman77]

Interesting Dave,
I wonder what equipment you use to monitor the radon levels.
We have none at my location in Cambridgeshire but I do have several radiation detectors to monitor the various types; alpha, beta, gamma here.
Do you do constant recorded readings or just random ones?
Mike.

[PolwinDave]

Hi Mike,
Thanks for the reply.
It's a long story Basically, we had a 3 month etch test by the NRPB early this year & found high levels (4k Bq/m-3) I had a number of contractors around to look but I was concerned by their non-scientific approach. ("we'll put a sump in somewhere and that'll sort it") I ended up reading everything I could find on the topic, pestering experts in the field and then borrowing four monitors - two Sun Nuclear Continuous and two cheapo's. My idea being that if I could find the levels in various parts of the house it would help to try to decide where to best locate a sump and diy a solution.
Eventually I got the levels down to below 100 Bq/m-3 through two sumps to a fan and a separate positive input ventilation system(PIV). The PIV was really to deal with condensation but it helped the radon as well.

However, whilst sorting it out, I noticed a strong and variable diurnal pattern in radon and so did a lot of analysis against data from Culdrose because the published papers on radon didn't really come to any firm conclusions about what was causing the pattern. The theory goes that it's caused by a combination of wind, pressure and temperature difference operating on the stack effect of a house.

Whilst the theory may be correct, none of the papers I saw showed convincing evidence and my own efforts with the Culdrose info more or less drew a blank. I eventually spoke to two meterologists about this and we concluded that my location (half way up a hill in a valley about 1mile from the coast) might be producing odd & quite local temp/pressure/wind variation that could explain why there was little correlation with the Culdrose data.

I'm convinced that soil moisture and permeability are intervening variables but I couldn't stretch financially to such sensors, so I decided on the WH1090 as a compromise. I've been recording hourly radon levels in two parts of the house since the end of August.

BTW I've recently bought some contamination monitors from the auction site and have managed to repair two of the four without schematics but I've only got a pancake probe which is pretty sensitive to alpha, beta & gamma, so I can't discriminate adequately at the mo. Do you have any data on alpha probes or schematics of the NE PCM 5/1 or the EMI type 3 PCM?
Regards
Dave

[Repairman77]

Hi Dave,

A very interesting survey you are doing.

With regard to monitors I don't have any info on the circuitry but if you have a Alph/Beta/Gamma monitor that should give you a good idea.
Gamma will show as background radiation unless you have a local source very close by (I know Cornwall has some Earth elements in the rocks). Beta is rarer and normally comes along with a radiation source such as Radium, Uranium, etc. It's blocked by a few mm of aluminium. Alpha is of course the one associated with Radon and Alpha can be blocked with a piece of card or a few mm of perspex.

If you take a reading and then add a filter of paper, then aluminium and record the readings you can do a subtraction routine.
i.e. No filter 100cps, with aluminium 70cps, them Gamma would be 70cps and Beta 30cps.
However as you are likely to have no appreciable amount of Gamma and Beta most of the radiation you receive will be Alpha.
I Guess you knew all this anyway so apologies if you did.

The real answer is to get a proper Alpha (only) monitor; they occasionally turn up on ebay, etc. and don't cost a fortune.
Obviously Alpha in Radon is in the actual air and should give a reasonable reading, whereas a normal Alpha source radiation will fade after a few inches.

Alpha monitors are not a thing you can construct easily as you need the special sensor, whereas Gamma/Beta monitors are pretty easy to construct with a Geiger tube; although they are cheap and plentiful these days and hardly worth the bother.

Do you get substantial readings on your counter from the Radon or is it not much more than the normal background radiation?

Mike.

[PolwinDave]

Hi Mike
I bought an ex-mod alpha only probe on ebay the other day - whether it will actually work at all or be sensitive enough remains to be seen as it's not arrived yet. I'll let you know.

I've just tried the pancake on the NE 5/1 PCM which has alpha only, alpha+beta, beta only and GM settings. I'd previously thought that I was getting about the same background on each setting and so assumed that the PCM was unable to discriminate the pulse heights from the probe but I've just noticed that I'm only getting readings on alpha, alpha plus beta (about 45-60 counts per minute) and on the GM setting (about 40 CPM), so it seems that the pancake probe may be discriminating to some extent.
Dave

[Repairman77]

Looks like you're getting somewhere Dave.

I have one of those pancake detectors somewhere. I think it picked up mostly Alpha but a bit of Beta and Gamma too.
Will have search it out and try again.

I hope your Alpha detector works OK when you get it; have you got the necessary equipment to plug it in?
I'm not sure how many volts they take to energise them?

I found some old lenses that were very rich in Alpha and use them to check detectors.
They are slightly yellow and contain Earth elements.

Mike.