Strontium-90 (Worksheet)

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Name: ______________________________

Section: _____________________________

Student ID#:__________________________

Work in groups on these problems. You should try to answer the questions without referring to your textbook. If you get stuck, try asking another group for help.

Today’s dependence on fossil fuels, the environmental effects of using fossil fuels and the increasing costs of fossil fuels have lead chemists and fuel scientists to investigate other avenues for energy generation. One of these alternatives is nuclear power. Currently, the amount of energy generated by nuclear power is far below its potential. The reasons for this are varied but primary among them is the question, what do we do with the radioactive wastes?

Using the attached paper and the leading questions. Critically evaluate the problems associated with the deep geological repository concept for nuclear waste. Identify how it is done, what the drawbacks are and if this is something that should continue to be pursued. Remember Yucca Mountain was scheduled to open 10 years ago and now it is not expected to become a respository for nuclear waste until 2021! In particular focus your efforts on the storage issues associated with Strontium-90.

“Chemistry related to isolation of High-Level Nuclear Waste”, Darleane C. Hoffman, Gregory R. Choppin, J. Chem. Educ., 63, 1986, 1059-1064.

Key Questions

Write the nuclear reactions for the nuclear fission of uranium or plutonium.
Figure 1 notes that Strontium can either be “once through” waste or “reprocessed” waste. What is meant by these terms?
What are the 4 main geological types considered for waste disposal?
What is tuff?
What are the most important environmental influences that must be considered when picking a disposal site?
What are the 3 most important aspects of storage units/sites?
The article mentions the degradation of the encapsulated radioactive waste, what do you believe is the focus of the encapsulation, long term storage or containers that breakdown once the radioactivity has dissipated?
On page 1061, last paragraph, column 1, the author compares kinetic with equilibrium factors, what do they man by this?
“What are some of the chemical and geochemical reactions that can influence the retention or passage of radionuclides from the glass to the surface of the ground through the burial site?” (directly from paper)
What are the main components that escape to the groundwater?
Why is it an advantage to have Fe²⁺ in the water surrounding a waste recepticle?
Why is it an advantage that glass is not crystalline?
What other materials are being considered and why are they at the top of the list?
What is the function of the clay around the outside of the sample capsule?
Address the issues related to the scale-up of research carried out on this subject.
What can be learned from the Oklo natural reactors? http://www.ocrwm.doe.gov/factsheets/doeymp0010.shtml
Finally, what is your opinion of this paper? Did you find it informative or dated? Based on the work presented here, what do you think about the Yucca Mountain project? Is this the way to dispose of our radioactive wastes?

Reference

Kelley J. Donaghy, SUNY-ESF