Bandelier National Monument 1 hour drive from Santa Fe; 30 minutes from Los Alamos.
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Transcript of Bandelier National Monument 1 hour drive from Santa Fe; 30 minutes from Los Alamos.
Measuring Radiation
• Coming from a source– Curie (Ci) – Becquerel (Bq)
• Absorbed by a person– Rad– Gray (Gy)
• Biological risk– Rem– Sievert (Sv)*
• Definitions– Ci: 37 x 109 disintegrations/second– Bq*: 1 disintegration/second– Or: the amount of a radioactive material
released• Chernobyl released 81 x 106 Ci of cesium Cs134
Cs135 Cs137.
Rad (radiation absorbed dose):Gray* (Gy): 100 rad
Rem: rad x Q (quality factor)Sievert* (Sv): 1 SV = 100 rem
Rads or Grays depend on the type of radiation:(alpha, beta, gamma, X-ray)
*Systeme Internationale
Exposure to Radiation
• Average annual exposure:• naturally ~ 360 mrems• Occupational exposure• 5,000 mrem/year
• http://www.ans.org/pi/resources/dosechart/
• (Website of the American Nuclear Society, which considers itself the “recognized credible advocate for advancing and promoting nuclear science and technology”.)
• Common sources (in mrem)• Cosmic rays: 26• Construction: 0-7• Terrestrial: 30• Power plants: 0.04• From food & water - 40• From air - 200 (now 228)• Medical procedures• whole-body CT scan: 1000• chest X-ray: 10• chest CT scan: 700 • Dental X-ray: 4-15 (now 0.5)• barium enema: 405 (now 800)• Plutonium-powered pacemaker: 100
mrem
Sources of Exposure to Radiation in the United States Today
whyfiles.org/020radiation/ index.php?g=4.txt
Understanding the toxicity of radioactivity
• Early experimenters• Manhattan Project• Civilian uses
– Medical• Diagnostic
– X-rays• Therapeutic
– Baths– X-ray treatments
– Consumer goods• Watch dials• Fluoroscopes
• Nuclear power– Post WW II
Radon: the Indoor Air Pollutant
• U238 --> radium --> radon• Radon
– Inert gas– Short half-life– Radon daughters are not inert
• Source of radon:– Uranium in soil, rock strata
• Recognition of problem– 1985, Reading PA
• “Reading Prong”• Also
– Florida -- phosphate mining– Rockies --uranium tailings– Illinois - radium in bedrock
Risk Perception
• People fear risks that are– Catastrophic– Mysterious– Not in their control
• People accept risks that are– Incremental– Well understood– Seemingly under their control
Arguments For Nuclear Power
• Intrinsically cheaper– Uranium is plentiful in the US
• Does not generate greenhouse gases• Safer than coal or oil
– Include costs of • Mining• Transport• Air pollution
• All forms of energy generate hazardous waste
• Technology to deal with small amounts of high-level waste exists– Reprocessing plutonium means
we will enver run out of nuclear fuel
• Low level waste is not a problemCoal-fired plant near Dussledorf, Germany
For a thorough defense, see: http://www.phyast.pitt.edu/~blc/book/chapter11.html
Arguments Against Nuclear Power
• Failures are catastrophic• The technology is not safe• Wastes are hazardous for millennia• Cost estimates must include waste
disposal• Mining is as hazardous as coal
mining if long-term effects are included
• Technology to deal with not-so-small amounts of high-level waste does not exist
• Reprocessing plutonium is an invotation to nuclear terrorism
• Low level waste is a problem
Three Mile Island: 1979
Arguments Against Nuclear Power: Chernobyl
• 25 April 1986• Graphite-moderated reactor
– Obsolete– Not used for power plants in US
• Melt-down• Explosion• 70% of nuclear material spewed out• 7,000-10,000 direct deaths• 300-400 millio exposed in 15 countries
– 150,000 at risk of thyroid cancer– 700,000 children at risk of
leukemia• 2 million acres farm land unuseable
– 20% of arable land in Ukraine• $400 billion costs (in USSR/Ukraine)• 200 years to repair the damage
Air Quality Varies by Region
Best days in east ~ worst days in mountain/west
East: 18-73 mile visibilityWest: 63-220 mile visibility
26 mi
137 mi
Smog-Related Atmospheric Molecules
• Major:– Nitrogen: N2
– Oxygen: O2
– Carbon dioxide: CO2
• Minor:– Oxides of nitrogen: Nox
– Sulfur dioxide: SO2
– Ozone: O3
– Hydrocarbons– Industrial pollutants
• Reactions of Interest– S + O2 --> SO2
– SO3 + H2O --> H2SO4
– N2 + O2 --> NO2
– NO2 + H2O --> HNO3
Interactions1. Generation of atomic oxygen:
NO2 + hv --------> NO + O Where hv = light at < 440 nm.
2. Ozone formation:
O + O2 + M ----> O3 + M M = 3rd molecule, typically N2
or O2
.
3. Ozone destruction:
NO + O3 ----> NO2 + O2
4. Hydroxy radical formation:
4 O + H2O 2 OH
O3 + H2O ------> 2(OH) + O2 at wavelengths < 320 nm.
Formation of peroxyacetyl nitrates (PAN)
• RH + OH H2O + R where RH is any hydrocarbon
• R + O2 RO2 (very fast)
• RO2 + NO NO2 + RO where R’CHO is an aldehyde
• RO + O2 R’CHO + HO2 (very fast)
• R’CHO + OH R’CO + H2O where R’CO is an acyl radical, and
• R’CO + O2 R’C(O)O2 (very fast) R’C(O)O2 is an acylperoxyl radical
• R’C(O)O2 + NO2 R’C(O2)NO2 where R’C(O2)NO2is an acylperoxyl
nitrate
R’-C=O O-O-NO2