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This is a question related to current events, but I want to ask about the physics, which are not explained in any news article that I can find.

Ernest Moniz and John Kerry wrote an op-ed in the Washington Post about the recent nuclear deal with Iran. In it, they say that even though inspections can be delayed for 24 days, that delay is not a problem, because "environmental sampling can detect microscopic traces of nuclear activities even after attempts to remove evidence."

My question is: how does this detection work, and how hard is it to defeat? I've studied some college level chemistry and physics, but I'm not an expert. My first guess was that the radioactive material in question would be emitting radiation that would alter the nuclei in the walls of any building or underground lab, and those altered nuclei would also be radioactive and detectable by the IAEA, even after 24 days. Maybe I'm way off on that guess, but if that were true, I can imagine ways to create thick moveable walls (not easy, but within a government budget) that could hide activity and defeat a delayed inspection. So, how does it work?

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    $\begingroup$ This is an excellent question insofar that Physics SE users should have the expertise to answer and good answers help keep public officials answerable to their electors: there is a tendency to throw any rubbish scornfully at the public with the haughty assumption that people are too stupid to know the difference. There is a partial overlap with Skeptics SE and you should consider that site if you don't get the answer you want: many of those guys are physicists with a debunk motivation. $\endgroup$
    – Selene Routley
    Commented Jul 24, 2015 at 1:33
  • $\begingroup$ Related: physics.stackexchange.com/q/77975. $\endgroup$
    – Kyle Kanos
    Commented Jul 24, 2015 at 1:44
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    $\begingroup$ The IAEA applies a whole slew of different tools, and I have never been conversant with everything they do. Part of it is direct detection of radionucleides, and other parts are in infrastructure and logistics monitoring. It's a complicated business and I suspect that they don't provide complete details on how they go about it. $\endgroup$
    – dmckee --- ex-moderator kitten
    Commented Jul 24, 2015 at 14:14
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    $\begingroup$ I'm focused on the direct detection part of the question. I did find this: iaea.org/sites/default/files/inspectors.pdf From that, it sounds like hiding it might be extremely difficult or improbable, but not technically impossible. $\endgroup$
    – Rob N
    Commented Jul 25, 2015 at 18:18
  • $\begingroup$ During the run-up to the US invasion of Iraq, in 2003 or thereabouts, I attended a talk by Scott Ritter about the Iraqi weapons inspection program. One of the things he said was (my paraphrase) "These facilities are big industrial installations that deal with lots of nasty chemicals. They are impossible to hide. If there were a way to hide them, it would be big business --- don't you remember the Love Canal?" $\endgroup$
    – rob ♦
    Commented Apr 29, 2016 at 22:08

2 Answers 2

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Ernest Moniz and John Kerry wrote an op-ed in the Washington Post about the recent nuclear deal with Iran. In it, they say that even though inspections can be delayed for 24 days, that delay is not a problem .My question is: how does this detection work, and how hard is it to defeat?

Let us have the info as to how the monitoring of Nuclear establishments/Nuclaer Weapon explosion/Power plant accidents get monitored through radiation fall out by Regulatory Authorities and then get a picture about the answer(probable) to the question:

Following Info. may be helpful-

The results of NRB-USA monitoring have shown the presence of natural and weapons fallout radiation and in a few instances, very low levels of radioactive material of nuclear plant origin.

A number of studies by the Radiation Public Health Project assert that levels of radioactive strontium-90 (Sr-90) are rising in the environment.

Strontium-90 (90Sr) is a radioactive isotope of strontium produced by nuclear fission, with a half-life of 28.8 years.

It undergoes β− decay into yttrium-90, with a decay energy of 0.546 MeV. Strontium-90 has applications in medicine and industry and is an isotope of concern in fallout from nuclear weapons and nuclear accidents.

The biological half-life of strontium-90 in humans has variously been reported as from 14 to 600 days.

Sr-90 comes from three sources: 1. fallout from above-ground explosions of nuclear weapons testing 2. radioactive releases from nuclear power plant accident and 3. radioactive releases from nuclear power plants into the environment.

By far, the largest source of Sr-90 in the environment (~99%) is from weapons testing fallout.

The general focus on human health monitoring here is on the isotopes cesium-137, iodine-131, and strontium-90 since they are relatively volatile and thus can contaminate large areas.

The concentration of Radio nuclides that may be released is limited to levels which, if inhaled or ingested continuously over the course of a year, would produce a dose of no more than 100 millirem.

The limits are based on radiation protection recommendations of both the National Council on Radiation Protection Measurements and the International Commission on Radiological Protection organizations resulting from ongoing research.

Nuclear power plants are further limited by their license conditions to keep radioactive material in effluents “as low as reasonably achievable” so that dose criteria for releases to unrestricted areas are five millirem for releases into the air and three millirem for liquid releases.

All power plant operators are required to file a report of these discharges annually with the NRC. These reports, which are publicly available. The concentrations of radionuclides released into the environment from a nuclear facility are generally too low to be measurable outside the plant’s boundary.

Ref:

http://www.geigercounter.org/radioactivity/isotopes.htm https://en.wikipedia.org/wiki/Strontium-90 www.nrc.gov › ... › Radiation Protection › How NRC Protects You

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  • $\begingroup$ As the answer was becoming large ,i did not give the details of radiation detection apparatus/contraptions which can be usually found on the net/wiki. $\endgroup$
    – drvrm
    Commented Jul 18, 2016 at 9:22
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Once an air sample is taken, it is possible to analyze the constituent atomic species with high sensitivity using laser cooling in a magneto-optical trap. In particular, the amount of radioactive isotopes can be specified, particularly well for Rubidium and Cesium.

I heard this on a conference. Maybe you can find more info if you search in the field of ultra-cold atoms or AMO physics.

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