#24 - After a nuclear power plant accident, researchers

[Administrator]

Complete Question Explanation

Must Be True. The correct answer choice is (B).

According to this stimulus, the researchers found iodine, tellurium, and cesium in the downwind atmosphere. Within that same sentence, the speaker specifies that the researchers found no heavy isotopes in the downwind atmosphere.

Later, the speaker introduces the fact that if radioactive material entered the atmosphere directly from the core, that material would contain heavy isotopes. We can thus infer that there are heavy isotopes in the nuclear core, and that a core ejection would not explain the researchers' findings.

We are also told that fuel rods never contain significant quantities of tellurium isotopes, which forces us to look for another origin for the downwind isotope discovery.

The final two sentence tell us that steam may have been in contact with the core, and that if it had been, it could have easily dissolved - and plausibly carried - the three isotopes that the researchers found downwind. This ultimately leads us to the correct inference. Answer choice (B) states the material that the researchers found was carried by steam released from the plant.

Answer choice (A): This is basically an Opposite Answer, so we can quickly eliminate it, as it's likely that the radioactive material came from the core, rather than the fuel rods.

Answer choice (B): This is the correct answer. The stimulus tells us that there are heavy isotopes in the core, and that "radioactive material ejected into the atmosphere directly from the core would include heavy isotopes." Since we didn't find heavy isotopes, it seems unlikely that the stuff we found was ejected directly from the core. But the steam is an alternative to that scenario! What if, instead of being ejected directly from the core, those isotopes were carried by steam that came into contact with the core? Not a direct ejection, but an indirect cause - the steam comes into contact with the core, dissolves the isotopes of iodine, tellurium, and cesium, and carries them along as vapor/gas, and that's what we found downwind? Nothing was ejected from the core at all, just some things were picked up and carried by the steam? That's the inference we should be making here! It's not likely to be the fuel rods, and it's not likely to be a direct ejection of material from the core, but it could be the result of steam being released that was in contact with the core.

Answer choice (C): This is a bait-and-switch, trying to swap "not the source of the radioactive materials" for "not damaged," which are two very different things.

Answer choice (D): This is the other attractive answer choice, but fails when we consider that we don't know anything about what the fuel rods contain, so we don't have any basis to support an inference that the material came from them.

Answer choice (E): is unsupported by the stimulus, so immediately wrong.

[OPD]

Is the test taker supposed to ignore the presence of heavy isotopes in the atmospheric discovery and their non-existence in the core?

[Francis O'Rourke]

Hi OPD,

It looks like you mixed up where heavy isotopes are located. According to this stimulus, the researchers found iodine, tellurium, and cesium in the downwind atmosphere. Within that same sentence, the speaker specifies that the researchers found no heavy isotopes in the downwind atmosphere.

Later, the speaker introduces the fact that if radioactive material entered the atmosphere directly from the core, that material would contain heavy isotopes. We can thus infer that there are heavy isotopes in the nuclear core, and that a core ejection would not explain the researchers' findings.

We are also told that fuel rods never contain significant quantities of tellurium isotopes, which forces us to look for another origin for the downwind isotope discovery.

The final two sentence tell us that steam may have been in contact with the core, and that if it had been, it could have easily dissolved - and plausibly carried - the three isotopes that the researchers found downwind. This ultimately leads us to the correct inference. Answer choice (B) states the material that the researchers found was carried by steam released from the plant.

Let me know if this helps.

[Margo]

It looks like you mixed up where heavy isotopes are located. According to this stimulus, the researchers found iodine, tellurium, and cesium in the downwind atmosphere. Within that same sentence, the speaker specifies that the researchers found no heavy isotopes in the downwind atmosphere.

Later, the speaker introduces the fact that if radioactive material entered the atmosphere directly from the core, that material would contain heavy isotopes. We can thus infer that there are heavy isotopes in the nuclear core, and that a core ejection would not explain the researchers' findings.

We are also told that fuel rods never contain significant quantities of tellurium isotopes, which forces us to look for another origin for the downwind isotope discovery.

The final two sentence tell us that steam may have been in contact with the core, and that if it had been, it could have easily dissolved - and plausibly carried - the three isotopes that the researchers found downwind. This ultimately leads us to the correct inference. Answer choice (B) states the material that the researchers found was carried by steam released from the plant.

Let me know if this helps.

Hi Francis,
I'm still struggling with this question.
My understanding is that the atmosphere downwind has: iodine, tellurium, cesium (NO heavy isotopes).
The material came EITHER from spent fuel rods OR from the plant's core. Since spent fuel rods don't have significant tellurium, then the material must have come from the plant's core.
The plant's core has: heavy isotopes, iodine, tellurium, and cesium.

I have trouble with B: that radioactive material detected by the researchers was carried by the steam. Because the researchers did NOT detect heavy isotopes but the plant's core has heavy isotopes, are we assuming that the steam was able to dissolve the heavy isotopes? This wasn't explicitly stated so I was confused. Is the assumption that the steam was in contact with the core, picking up iodine, tellurium, cesium, and heavy isotopes, then the steam dissolved the heavy isotopes before the researchers could measure them?

Also, if the steam easily dissolves the iodine, tellurium, and cesium isotopes, why weren't these dissolved as well? I guess that just because they could be easily dissolved, doesn't mean they necessarily were..

Sorry if my thoughts are jumbled! Thanks

[Adam Tyson]

Happy to help, Margo! The stimulus tells us that there are heavy isotopes in the core, and that "radioactive material ejected into the atmosphere directly from the core would include heavy isotopes." Since we didn't find heavy isotopes, it seems unlikely that the stuff we found was ejected directly from the core. But the steam is an alternative to that scenario! What if, instead of being ejected directly from the core, those isotopes were carried by steam that came into contact with the core? Not a direct ejection, but an indirect cause - the steam comes into contact with the core, dissolves the isotopes of iodine, tellurium, and cesium, and carries them along as vapor/gas, and that's what we found downwind? Nothing was ejected from the core at all, just some things were picked up and carried by the steam? That's the inference we should be making here! It's not likely to be the fuel rods, and it's not likely to be a direct ejection of material from the core, but it could be the result of steam being released that was in contact with the core. Boom!

[ser219]

I hesitated to pick B because I was confused by "the core contains iodine, tellurium, and cesium isotopes, which are easily dissolved by steam.


I did not know if this dissolving meant that steam could contain or could not contain the cesium, iodine, or tellerium. How can we know this? Or is this something the test makers just expect you to know that I did not? I'm not a science person but I usually do well on lsat science stuff but this one was confusing for me.

[James Finch]

Hi Ser,

What you describe is a common problem for this particular question. The two inferences that the stimulus is trying to get to are that there has to be a vector for the radioactive isotopes to escape the core, as there aren't any heavy isotopes present as there would be if there was a direct expulsion of material from the core to the atmosphere, and that steam could function as this vector, as the steam could carry the dissolved radioactive isotopes from the core out into the atmosphere. The problem is that to get that second inference, you have to know that "dissolve by" contains the possibility that the isotope isn't fundamentally changed by dissolving into the steam, but may be transported within it to another location while still retaining its characteristics as a radioactive isotope. Because that isn't made explicit, getting to the correct answer choice is more of an exercise in process of elimination rather than accurately Prephrasing and matching that Prephrase to the correct answer choice.

(A) is basically an Opposite Answer, so we can quickly eliminate it, as it's likely that the radioactive material came from the core, rather than the fuel rods. (B) is possible, but not one that is easy to immediately pick. (C) is a bait-and-switch, trying to swap "not the source of the radioactive materials" for "not damaged," which are two very different things. (D) is the other attractive answer choice, but fails when we consider that we don't know anything about what the fuel rods contain, so we don't have any basis to support an inference that the material came from them. (E) is completely unsupported by the stimulus, so immediately wrong. That leaves only (B) as a potential correct answer choice, so even with if you're a bit uncertain about it you should be confident in your methodology and move on at this point.

Hope this helps!

[ArizonaRobin]

I hesitated to pick B because I was confused by "the core contains iodine, tellurium, and cesium isotopes, which are easily dissolved by steam.


I did not know if this dissolving meant that steam could contain or could not contain the cesium, iodine, or tellerium. How can we know this? Or is this something the test makers just expect you to know that I did not? I'm not a science person but I usually do well on lsat science stuff but this one was confusing for me.

I had the same problem. I thought that the steam would dissolve, therefore destroy, the isotopes so the only way it seemed that these could come from the core was through some other, unmentioned, process. So answer choice B seemed to be directly negated by the last sentence of the stimulus. My process of elimination led me to C which, while not perfect, was supported by one premise and not negated by any others.

[Dave Killoran]

I hesitated to pick B because I was confused by "the core contains iodine, tellurium, and cesium isotopes, which are easily dissolved by steam.


I did not know if this dissolving meant that steam could contain or could not contain the cesium, iodine, or tellerium. How can we know this? Or is this something the test makers just expect you to know that I did not? I'm not a science person but I usually do well on lsat science stuff but this one was confusing for me.

I had the same problem. I thought that the steam would dissolve, therefore destroy, the isotopes so the only way it seemed that these could come from the core was through some other, unmentioned, process. So answer choice B seemed to be directly negated by the last sentence of the stimulus. My process of elimination led me to C which, while not perfect, was supported by one premise and not negated by any others.

Hi Robin,

The problem is that dissolve doesn't have to mean destroyed. Think about dissolving sugar into water—are the elements of sugar then completely gone? No, and that's the idea they are getting across here, that the elements of the isotopes persisted.

If it helps, here's the Oxford dictionary definition: "(with reference to a solid) become or cause to become incorporated into a liquid so as to form a solution."

Thanks!

[yrresnik]

Complete Question Explanation

Must Be True. The correct answer choice is (B).

According to this stimulus, the researchers found iodine, tellurium, and cesium in the downwind atmosphere. Within that same sentence, the speaker specifies that the researchers found no heavy isotopes in the downwind atmosphere.

Later, the speaker introduces the fact that if radioactive material entered the atmosphere directly from the core, that material would contain heavy isotopes. We can thus infer that there are heavy isotopes in the nuclear core, and that a core ejection would not explain the researchers' findings.

We are also told that fuel rods never contain significant quantities of tellurium isotopes, which forces us to look for another origin for the downwind isotope discovery.

The final two sentence tell us that steam may have been in contact with the core, and that if it had been, it could have easily dissolved - and plausibly carried - the three isotopes that the researchers found downwind. This ultimately leads us to the correct inference. Answer choice (B) states the material that the researchers found was carried by steam released from the plant.

Answer choice (A): This is basically an Opposite Answer, so we can quickly eliminate it, as it's likely that the radioactive material came from the core, rather than the fuel rods.

Answer choice (B): This is the correct answer. The stimulus tells us that there are heavy isotopes in the core, and that "radioactive material ejected into the atmosphere directly from the core would include heavy isotopes." Since we didn't find heavy isotopes, it seems unlikely that the stuff we found was ejected directly from the core. But the steam is an alternative to that scenario! What if, instead of being ejected directly from the core, those isotopes were carried by steam that came into contact with the core? Not a direct ejection, but an indirect cause - the steam comes into contact with the core, dissolves the isotopes of iodine, tellurium, and cesium, and carries them along as vapor/gas, and that's what we found downwind? Nothing was ejected from the core at all, just some things were picked up and carried by the steam? That's the inference we should be making here! It's not likely to be the fuel rods, and it's not likely to be a direct ejection of material from the core, but it could be the result of steam being released that was in contact with the core.

Answer choice (C): This is a bait-and-switch, trying to swap "not the source of the radioactive materials" for "not damaged," which are two very different things.

Answer choice (D): This is the other attractive answer choice, but fails when we consider that we don't know anything about what the fuel rods contain, so we don't have any basis to support an inference that the material came from them.

Answer choice (E): is unsupported by the stimulus, so immediately wrong.

Why would it not be strongly supported to assume from the stimulus that rods contain tellurium? Is says doesn’t contain significant which strongly implies contains less than significant no? Which would make answer choice d pretty even with b.