Sadly, today I heard in the news that EPZ's* request to allow use of MOX fuel in the 30 year old Borssele NPP was granted by Dutch Ministry of Economic Affairs (MinEZ). Publication here.
Personal Geiger counter, radiation measurements in the city of Goes, The Netherlands. Note: I'm not using officially calibrated equipment, so don't draw any conclusions. Just use the graphs for comparing variations over time.
About this blog
So I got the urge to be able to detect and measure radiation by my own, especially since I live within a 15km radius from the NPP of Borssele and a 30km radius from the four reactors of Doel NPP, Belgium.
Browsing the internet, I found some relatively cheap ex-army radiation detectors at an army-dump shop. One of them appeared to be suitable to even detect the (usually low) background radiation levels: A Frieseke & Hoepfner FH40T Geiger counter (fitted with a FHZ76V energy-compensated geiger-mueller tube), sensitive to γ (gamma) radiation and β (beta) radiation over 0.25MeV.The FHZ76V tube actually contains a Valvo 18550 tube, which is equivalent to Centronics ZP1320, Mullard Mx164 and LND-713 (found in this Probe Selection Guide and here)
The specs of the ZP1320 tube claim a sensitivity of 9cps/mR/h for Cs-137 (540cpm/mR/h). For 'normal' background (0.025-0.045mR/h) this results in a counting rate of approx.10-20cpm.. Where I live, I measure values varying between 4cpm up to 25cpm. This variation is caused by the randomness of the decay of radioactive elements.
Note:
1 R = 8.77 mGy
1 Gy = 115 R
For sake of simplicity, in our calculations we simply use 1R = 10mGy and 1Gy= 100R. And so is 10µR = 0.1µSv.
This approximation is good enough for this experiment.
There are 3 types of radiation:
α (alpha) decay is helium nucli being released, (beta) decay is electrons (β-) or positrons (β+) and γ (gamma) decay is electromagnetic radiation (like X-rays).
This Geiger-Mueller tube is only sensitive to β and γ radiation. The calibration is only correct for the γ radiation (662keV) emitted from Cs-137 .
I am now on the lookout for a device that can detect alpha radiation too. But the current situation in Fukushima has stirred up the market (crazy prices, run out of stock) for detection devices so I better wait until better times.
Thursday, June 30, 2011
Borssele NPP gets permit for MOX fuel
Sadly, today I heard in the news that EPZ's* request to allow use of MOX fuel in the 30 year old Borssele NPP was granted by Dutch Ministry of Economic Affairs (MinEZ). Publication here.
Wednesday, June 8, 2011
Disassembly and repair of FH40T geigercounter
To reach the components concerned, the circuit boards need to be removed from the FH40T's housing.
To make removal possible, several wires need to be unsoldered.
To document the situation, to be able to connect all wires after repair of the circuit, I took this series of pictures: