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Ch.21 - Nuclear Chemistry
All textbooksBrown 14th EditionCh.21 - Nuclear ChemistryProblem 66
Chapter 21, Problem 66

Which type or types of nuclear reactors have these characteristics? (a) Can use natural uranium as a fuel (b) Does not use a moderator (c) Can be refueled without shutting down

Verified step by step guidance
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Step 1: Understand the characteristics of natural uranium as a fuel. Natural uranium consists mostly of U-238 with a small percentage of U-235. Reactors that can use natural uranium typically require a neutron economy that allows for the use of U-238, such as heavy water reactors.
Step 2: Identify reactor types that do not use a moderator. A moderator is used in most reactors to slow down neutrons, but fast reactors do not use a moderator as they rely on fast neutrons to sustain the chain reaction.
Step 3: Consider the ability to refuel without shutting down. This characteristic is often associated with certain types of reactors that allow for continuous fuel replacement, such as liquid metal-cooled fast reactors.
Step 4: Combine the characteristics to identify potential reactor types. Look for reactors that can use natural uranium, do not use a moderator, and can be refueled while operating, such as certain types of fast breeder reactors.
Step 5: Review specific examples of reactors that meet these criteria. Research reactors like the CANDU reactor for natural uranium use and fast breeder reactors for the other characteristics.

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Nuclear Reactor Types

Nuclear reactors can be classified into various types based on their design and operational characteristics. Common types include pressurized water reactors (PWR), boiling water reactors (BWR), and fast breeder reactors. Each type has specific fuel requirements, cooling methods, and neutron moderation techniques, which influence their efficiency and safety.
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Natural Uranium Fuel

Natural uranium consists primarily of the isotope U-238, which is not fissile but can be used in certain reactor designs. Reactors that utilize natural uranium typically require a specific configuration to achieve a sustained nuclear reaction, often relying on fast neutrons rather than thermal neutrons, which are moderated in other reactor types.
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Refueling and Online Operation

Some nuclear reactors are designed for online refueling, allowing them to be refueled without shutting down. This capability enhances operational efficiency and reduces downtime. Such reactors often employ advanced designs that facilitate the safe replacement of fuel assemblies while maintaining critical operations.
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Related Practice
Textbook Question

The spent fuel elements from a fission reactor are much more intensely radioactive than the original fuel elements. (b) Given that only two or three neutrons are released per fission event and knowing that the nucleus undergoing fission has a neutron-to-proton ratio characteristic of a heavy nucleus, what sorts of decay would you expect to be dominant among the fission products?

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Textbook Question

Which are classified as ionizing radiation: X rays, alpha particles, microwaves from a cell phone, and gamma rays?