Physics 43 Ch 45 HW # 7: DOUBLE POINTS!!
The following problems are essay type ‘lab report’ problems in which you must explain your method,
assumptions and results. Box final numerical values and make it super easy to grade. Have fun with it.
Type your discussions. Plagiarism is illegal so don’t do it. If you quote someone, please note it.
1. After the sudden release of radioactivity from the Chernobyl nuclear reactor accident in 1986, the
radioactivity of milk in Poland was 2 000 Bq/L due to iodine-131 present in the grass eaten by dairy cattle.
Radioactive iodine (beta decay), with half-life 8.04 days, is particularly hazardous, because the thyroid
gland concentrates iodine. The Chernobyl accident caused a measurable increase in thyroid cancers among
children in Belarus. Write out decay equation. Estimate the dose received by a 30.0 kg child who drinks a
liter of radiated milk every day after the disaster in the first day, the first week, the first month and then in
a year. Do not assume a constant decay rate for long term exposure. Discuss the health risks, both short
term and long term. You can use this table to estimate the short term health risks due to the initial
exposure.
For the long term cancer risk, compare and contrast the risk from ICRP and the ECCR dose coefficients,
discussed in lecture and given below. The SI unit for dose is the Sievert (sievert (Sv) = 100 rem).
FYI: The ECCR model is described in detail here: http://www.euradcom.org/2011/ecrr2010.pdf.
2. In a study published by the journal Proceedings of the National Academy of Sciences, “Cesium-137
deposition and contamination of Japanese soils due to the Fukushima nuclear accident,” researchers
examined levels of the radioactive isotope cesium-137 in soil collected in and around the Fukushima
plant. (abstract, paper, movies here: http://www.pnas.org/content/108/49/19530.abstract) In the eastern
part of Fukushima prefecture soil levels of cesium-137 exceeded 2,500 Becquerel per kilogram, which
would leave food production in the area "severely impaired," according to the study. In a recent Business
Week article “Fukushima Farmers Face Decades of Tainted Crops as Fears Linger” Shin Shato from the
farm Ministry’s grain division in Japan said that the government banned rice containing more than 100
Becquerel of cesium per kilogram.
The amount of radioactive isotopes in soil that is absorbed into a growing plant is given by a “Transfer
Factor” which depends on many things such as the type of plant, soil, weather, stage of growth of the
plant, just to name a few. Many studies have been conducted by different organizations and institutions in
the past decades. Here is a table of transfer factors for Cs-137, where the factor is expressed as a unitless
fraction (multiply by a 100 to get the percent absorbed).
Transfer factors of
Leung, 2002)
137
Cs published by other Organization (Jalil et al., 2002; Shang and
Using the TF factors in the table determine the activity in the rice grown in the Fukushima prefecture
where the activity in the soil was over 2,500 Bq/kg. Discuss your reasoning (which TF you used and if
you averaged and why.) Using the same analysis in problem one, find the short and long term health risks
for eating 1 kg of rice and vegetables grown in this area per day for a day, week, month, year. Given your
results, comment on the 100 Bq/kg ban. Given the 30 year half life of Cs-137, comment on how long the
ban should last.
For more info: IAEA Final Report: RADIONUCLIDE TRANSFER FACTOR FROM SOIL TO PLANT
http://gea.unsl.edu.ar/pdfs/IAEA-GEA%20report.pdf
3. On their website (www.nei.org) to the Nuclear Energy Institute, the US nuclear power
industry lobby group claims: “Nuclear energy is America’s largest source of clean-air, carbon-free
electricity, producing no greenhouse gases or air pollutants.” Discuss the accuracy of this statement
considering the entire life cycle of nuclear power generation. The most comprehensive study to date is a
survey examining 103 other lifecycle assessments conducted by Benjamin K. Sovacool, Valuing the
greenhouse gas emissions from nuclear power: A critical survey, Energy Policy 36, June 2, 2008.
http://www.nirs.org/climate/background/sovacool_nuclear_ghg.pdf Both pro-nuke and anti-nuke
advocates refer to Sovacool to justify their arguments for and against nuclear power. You should look at it.
Here is a nice brief paper by a Stanford nuclear power student you might find useful:
http://large.stanford.edu/courses/2011/ph241/ali1/
Plagiarism is illegal so don’t do it. If you quote someone, please note it.