How does heavy water in a nuclear reactor help to keep the chain reaction going?

1 answer:

4 0

<span>Heavy water acts as a neutron moderator. The neutrons formed by fission come off at high velocity, but U-235 absorbs neutrons much more strongly when they are slowed down, so all so-called thermal reactors use a moderator to slow them down until they achieve the average velocity appropriate to the atoms of the moderator which is at approx 300 deg C in a water reactor. Other moderators can be light water or graphite. Heavy water has the advantage over light water that it absorbs fewer neutrons so natural uranium can be used, whilst light water requires enriched uranium fuel. Graphite in a very pure form is also a good moderator but requires a gas coolant, carbon dioxide has been used in magnox and agr reactors, but there is a time limit on the life of the reactor due to graphite corrosion, and these are now obsolete as far as new builds are concerned. The Soviet RBMK reactors used graphite but with a water coolant inside pressure tubes, but after Chernobyl there will certainly be no more of these built
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What mass of KNO, will dissolve in 100 g of water at 100°C?

Sphinxa [80]

Answer:

About 170-180 grams of potassium nitrate are completely dissolved in 100 g.

Explanation:

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In this case, according to the reported solubility data for potassium nitrate at different temperatures on the attached picture, it is possible to bear out that about 170-180 grams of potassium nitrate are completely dissolved in 100 g; considering that the solubility is the maximum amount of a solute that can be dissolved in a solvent, in this case water.

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vampirchik [111]

This problem is describing the state two gases have when separated and together as shown on the attached picture. First of all, diagram 1 shows how they are separated in two containers with apparently equal volumes, whereas diagram 2 shows the removal of the barrier so that they get mixed together.

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Therefore, the correct choice is:

C. The partial pressure of each gas in the mixture is half its initial pressure; the final total pressure is half the sum of the initial pressures of the two gases.

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