Nuclear fission and nuclear to thermal energy conversion

[kirsten_2009]

Homework Statement

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Suppose the main water pipe breaks in a nuclear power plant, shutting off the water flow. If the control rods fall immediately into place, stopping the chain reaction, is there still a problem?

Yes, because radioactivity continues to create lots of thermal energy. (A)
Yes, because the control rods stop only the fissioning of uranium and not the fissioning of plutonium. (B)
Yes, because the uranium can still fission even though it is not chain-reacting. (C)
No, because no heat can be created once the fission reaction is shut off. (D)
No, because the small amount of heat that continues being created is not enough to cause any danger. (E)

Homework Equations

The Attempt at a Solution

I'm thinking (D) -No, because no heat can be created once the fission reaction is shut off.

The fission of Uranium is what releases nuclear energy to heat water which then under less pressure turns into steam to turn a turbine no? but if the fission if uranium through it's chain reactions is stopped then there is no nuclear energy being released to heat the water averting a meltdown...correct?

 

[SteamKing]

The Japanese faced a similar real-life situation in 2011 after the tidal wave knocked out electricity powering the circulating water pumps which cooled the reactors at Fukushima:

http://en.wikipedia.org/wiki/Fukushima_Daiichi_nuclear_disaster

Read this article and see if D is still your final answer.

 

[kirsten_2009]

Ah interesting...thank you! so...although fission stops, still a lot of heat is produced by radioactivity so there is still definitely a problem. I choose (A).

 

[swag yolo]

you wouldn't happen to be in phy100 at u of t would you?

 

[HalfLostAndSearching]

Yes, you are correct. Once the chain reaction is shut off, no further nuclear energy is being released and therefore no thermal energy is being produced. While there may be some residual heat from the decay of radioactive elements, it is not enough to cause any significant danger. So, the correct answer is (D) - No, because no heat can be created once the fission reaction is shut off.