Nuclear radiation per MMBtu for coal plants?
ddrfreakazoid101 asked:
Coal power plants emmit nuclear radiation the air from burning coal mainly thorium and uranium 235 but others as well.
Coal power plants emmit nuclear radiation the air from burning coal mainly thorium and uranium 235 but others as well.
I am looking for the amount a typical coal plant emits per MMbtu of energy used.
Also I want the amount of Radiation produced daily per MW of power produced.
How would I go about doing that?
Radioactivity is a very tricky topic since it’s hard to make
meaningful measurements…there are many different types of
radioactivity, and not all are alike in terms of their energy
intensities, or potential effects.
Nonetheless, concerns over radionuclide emissions from power plants have led to some study and benchmarking of radioactive emissions, and I have summarized these here.
In a nutshell, though, there appears to be very little concern over this topic. Not because there isn’t a lot of radioactive material naturally present in coal (on the contrary, there’s quite a bit!), but because most of the radioactive materials are captured by pollution control devices in the US, and do not end up as direct atmospheric emissions.
Most….but not all. The US Environmental Protection Agency conducted what is considered the definitive study on this topic in 1998:
Study of Hazardous Air Pollutant Emissions from Electric Utility Steam Generating Units — Final Report to Congress
This is a 500-page report with several tons of detail, but one table, in particular has the key details you asked about. Table 9-3 (on page 330) gives the radionuclide emissions in units of miliCuries per billion KWh of electric generation. Check the report itself for the full details of the table, but I’ve excerpted some of the key emitters below:
Table 9-3. Average Annual Radionuclide Emissions per Operating Boiler Unit and per Billion Kilowatt-Hour Electricity Generated
Radionuclide……………………….mCi/billion KWh
Rn-220………………………………..1.1 x 10^2 = 110
Rn-222………………………………..2.0 x 10^2 = 220
U-238………………………………….1.5 x 10^0 = 1.5
U-234………………………………….1.5 x 10^0 = 1.5
Ra-226………………………………..1.2 x 10^0 = 1.2
Po-218………………………………..3.8 x 10^0 = 3.8
Pb-214………………………………..3.8 x 10^0 = 3.8
Po-214……………………………….3.8 x 10^0 = 3.8
Pb-210……………………………….3.8 x 10^0 = 3.8
Po-210……………………………….3.8 x 10^0 = 3.8
Po-216……………………………….2.4 x 10^0 = 2.4
Pb-212……………………………….2.4 x 10^0 = 2.4
K-40………………………………….5.3 x 10^0 = 5.3
The biggest emission source of radioactivity comes from Radon isotopes, which collectively (Rn-220 + Rn-222) account for 330 mCi for every billion KWh of electricity generated.
No other radionuclide makes much of a contribution, adding only about another 30 mCi all told, with K-40, and isotopes of lead and polonium accounting for most of the remainder.
You mentioned uranium and thorium in your question, but by themselves, they are fairly minor emission sources. Instead, they decompose, and their breakdown products are the key emitters.
The total radiation from air emissions at coal fired power plants, on average, is about 360 mCi per billion KWH.
Since you asked about BTUs as well as KWh, we can convert using the conversion factors found here:
1 kilowatt hour of electricity = 3413 BTUs
Hence, there is an average of 360 mCi per 3.413 trillion BTUs, or approximately 105 mCi per trillion BTUs.
I hope that fully answers your question.