Idealist - Radiation from North Korea's 2009 underground nuclear test

The easiest way to verify an underground nuclear test (and ascertain the size of the test and the type of nuclear blast) is by detecting the radioactive gases released after the explosion.

There are well over 100 different radioactive elements produced by nuclear blasts that are conducted either aboveground or underground. But usually the only type of radiation that escapes from underground nuclear blasts into the outside air - and available for detection - is the radioactive noble gases¹. These gases can be detected over a period of several weeks thousands of feet high at distances hundreds or thousands of miles away from the 'ground zero.' [Xenon-133 (half life of 5.2 days) was detected over Canada and tracked to North Korea's 2006 test (view: Xe-133 plume trajectory).]

Following North Korea's second nuclear test in May 2009, South Korea, Japan and the U.S. conducted sampling of the air downwind of the North Korean test site - when N.K. wasn't shooting off test missiles into the air! - and tried to detect traces of radioactive xenon, a common byproduct of a nuclear explosion. However, they couldn't find the 'signature' gases from North Korea's test for unknown reasons. Some speculated that it was a faked test. Or N.K. succeeded in a rare 100% containment of the gases.

What is this 'gas signature'? It would have probably been a mix of two Xenon gaseous isotopes, Xenon 133 and Xenon 135, in a specific 'activity ratio' (i.e., so many parts per million of one gas per parts per million of the other gas). After a 2-week (or so) period (when most of the Xenon-135 converts into Cesium 135), that activity ratio, because of the uneven rate of decay of the two isotopes, soon resembles that of the Xenon gaseous mix produced worldwide by nuclear power plants, which are continuously emitting a myriad of radioactive gases into our atmosphere. (Read more about radioactive gases in the grey boxed-feature and learn why most aren't used to detect nuclear explosions (hint: most are too short-lived)) A second method, using the ratio of detected Xenon-133m and Xenon-131m, can also be used to detect emissions from a leaked subsurface nuclear test.

About 8 percent of the elements created in the fission explosion comprise radioactive noble gases of krypton and xenon. These gases include:

Xenon-137 (half-life of 3.9 minutes) decays in a few minutes into Cesium 137, which collects in the muscles of humans and has a half-life of 30 years.
Krypton-90 (half-life of 33 seconds) decays in minutes into rubidium-90 (half-life of 2.91 minutes) and then quickly into strontium-90, which collects in human bones and teeth and has a half-life of 28 years.
Xenon-135, which has a half-life of 9.17 hours, decays into cesium-135 with a half-life of 3 million years.
Xenon-133, which has a half-life of 5.24 days, decays into cesium-133.
Metastable xenons - Xenon-131m, with a half-life of 11.93 days, doesn't emerge until the decay of its parent of Iodine-131 (half-life about 8 days). Xenon-133m, with a 2.19 day half-life, emerges from the decay of parent iodine-133, which has a half-life of 20.9 hours. Xenon-135m has a half-life of just 15.6 minutes. Its parent, I-135, has a half-life of 6.7 hours.
There's also Xenon -141, -143 and -144, which have half-lives of just 1.73 seconds, 5.11 milliseconds and 3.88 milliseconds, respectively, and decay into solid-form carcinogenic radioactive isotopes of cerium.
Krypton-89, with a half-life of 3.2 minutes, decays into strontium-89, which has a 52-day half-life.
Krypton-85, a beta and gamma emitter, is the only Krypton fission byproduct that takes more than a few days to decay fully. It has a half-life of about 11 years and sometimes can also be used to tell if a nuclear explosion occurred. Long-lived krypton and xenon and argon gases, like krypton 85 and xenon 133, are all heavier than air and thus they settle near the ground. Because we breathe in air whether it is radioactive or not, humans routinely intake radioactive noble gases from nuclear reactor emissions and leaks from underground nuclear test shafts into our lungs. In the lungs, these radio-chemicals get absorbed into the bloodstream and because they are soluble in fat they tend to accumulate in our 'fatty' deposits in our bodies where they give off Xray-like gamma radiation.
Fission explosions also create radioactive isotopes of the noble gas Argon. Among the longer-lived Isotopes of Argon are Argon-37, with a half-life of about 35 days, and Argon-39, with a half-life of 269 years. Argon-37, uniquely, can only be produced by a nuclear reaction; it is produced when neutrons bombard rock-fortified calcium. Argon-39, on the other hand, is regularly produced by nuclear reactors as neutrons convert potassium-39 (into Argon-39) and is also created by cosmic activity. Although Argon-37 can be a tracer for leaked underground nuclear explosions, it is difficult to detect⁴ and measure at low quantities (it later decays to chlorine-37).
Fission and fusion nuclear explosions also create Carbon-14, an unstable isotope (stable carbon predominantly exists as Carbon-12) that can be created by natural processes when Nitrogen-14 is bombarded by cosmic radiation in the form of neutrons. Nitrogen exists as either Nitrogen-14 or Nitrogen-15. Elemental Nitrogen, or nitrogen gas, is known as Nitrogen-14, which has an 'isotopic abundance' - meaning it comprises a percentage of total isotope quantity in nature - of 99.643%. [When you look at a periodic table, it is an arrangement of elements only by atomic number, which is the number of protons. The atomic weight, however, is the average weight of that element across all naturally-occurring isotopes, or the abundance-weighted average mass of an element. The word 'Isotope' doesn't necessarily mean anything toxic, or radioactive. Everything created by nature (and human) is an isotope. All elements exist only as isotopes. Many elements exist as many different isotopes, however not all do. Elemental sodium only exists naturally as Sodium-23. There are stable and unstable (radioactive) isotopes existing in nature. The unstable (radioactive) naturally occurring isotopes include all elements with an atomic number of 84 or greater (after elemental Bismuth).]

If North Korea's future nuclear tests result in a containment failure that leads to significant venting, the public health effects could be disastrous. (A smaller yet non-insignificant public danger exists from late-time seeps (see our Nevada Test Site underground test section) from underground test cavities.)

North Korea's 2nd test was similar in size (although no one knows what the yield really was) to Baneberry, a U.S. Nevada Test Site nuclear blast that badly leaked in 1970. Baneberry was a 10-kiloton nuclear blast that released six million Curies into the aboveground environment. According to the book 'KILLING OUR OWN', on the topic of Baneberry's fallout, 'In all of the states where the total radioactivity rose highest--Idaho, Montana, Oregon, Nevada, Washington, Nebraska, and as far away as Minnesota and Maine--infant mortality also rose sharply during the first three months after the test.' The book also states that 'a dangerously high concentration of Iodine-131, a radiation byproduct, was found in the milk of Utah and Nevada cows which had eaten vegetation exposed to Baneberry's fallout.'

If there was venting, the worst effects may come in the form of non-gaseous fission elements such as Iodine-131, which is bioaccumulative. Radioactive iodine does the most damage when it falls on grass, gets consumed by cows and goats, concentrates in milk, or other dairy products, and further concentrates in the thyroid glands of humans, where cancer can develop. Fallout may also contain Strontium-90 and Cesium-137 - also bioaccumulative - that can enter the global food chain. Anyone in the world can unknowingly consume foods like cheeses, apricots, and meats from areas contaminated by a leaked underground nuclear test.

Regrettably, in mid-2009 (and 2010) there is an information vacuum regarding the radiological dangers posed by present day underground nuclear testing by North Korea. Do people care about being fallout victims? Don't they know about the destructiveness of a 'Baneberry'? Read more about this in our oped piece 'How to Squash the Baneberry of the East a la Dorothy Gale.'

Can we expect more tests? The state-run North Korean news agency - KCNA website - stated on May 25 that, 'The DPRK will bolster up the war deterrent for self-defence in every way along the road already chosen by itself...'

Answer: The United States started testing first. And the U.S., by all appearances, has not pulled away from nuclear testing exercises. It is the last of the 'founding nuclear nations' to NOT close its nuclear test site. The Nevada Test Site, where over 1,000 nuclear tests were conducted, maintains an 18-month 'readiness' posture for nuclear testing resumption by order of the U.S. President. It is also where the U.S. continues to conduct nuclear experiments - including subcritical tests and simulations (i.e. Divine Strake) - that violate the spirit of test ban treaties.

Could it be that the U.S.'s nuclear experiment/testing posture is provoking North Korea (and other nations) to become a nuclear nation? Is its posture the 'chicken' that is laying these (N.K. underground) 'eggs'? Consider that eight days after the U.S. conducted its 23rd subcritical nuclear experiment in 2006 at the Nevada Test Site, the North Korean government made its first mention (on 9/7/06) that it may conduct a nuclear test. In that announcement, North Korea's Central News Agency noted that a South Korean group, the National Alliance for the Country's Reunification, made a statement accusing the United States' subcritical test as an "obvious criminal act of disturbing the global peace." North Korea's test was carried out in October 2006.

The U.S. is also among the nine last 'Annex 2 states' that have not ratified the Comprehensive Test Ban Treaty; the list includes: China, Egypt, India, Indonesia, Iran, Israel, North Korea, Pakistan and the United States.

¹CTBTO spokesperson Annika Thunborg: 'Radioactive noble gases will seep out [from an underground test site] even if you contain the particles. You can never contain it entirely.' May 29, 2009, PBS

⁴ The CTBTO Spectrum, a newsletter of the international organization of the CTBT, elaborates on the laboratory difficulties - and possibilities - in 37Ar detection: 'This isotope has a considerably longer half-life than the CTBT- relevant radio-xenon isotopes, and would so be more likely to remain in detectable quantities during the time-frame of an OSI [on-site inspection]. On the other hand, stable argon comprises an enormously larger fraction of standard air than does xenon, potentially resulting in unwieldy sample sizes once the chemical separation is accomplished. In addition, the determination of the sample activity is complicated by the very low energy of the emitted ionizing radiation. These difficulties could be mitigated by off-site measurement of samples in a designated laboratory – such a solution would be more profitable in the case of 37ar than in the case of the radio-xenons due to the longer life-time of the former.' (CTBTO Spectrum, Issue 7)

The 10-kiloton U.S. underground nuclear explosion in 1970 dubbed Baneberry released 6% of its radioactive load of gaseous and non-gaseous matter, amounting to 6 million Curies, into the environment because of a containment failure.

June 3, 2009 - Was N. Korea`s 2nd Nuke Test Faked? - “Krypton-85, however, is bound to be leaked no matter how tight the facility is sealed...Unless krypton-85 is detected, it will be difficult for the international community to confirm the test."

- If it was faked, it'd be on the scale of size of 'Minor Scale,' a 4.7-ton non-nuclear ANFO (diesel oil and fertilizer) surface explosion at WSMR in 1985.

June 2, 2009 - Noko missiles ARE messing up 'nuclear assessment: '..it is also difficult to determine the yield of the blast because there are many factors affecting it — including what kind of a detonator was used and how tightly the underground site was sealed' - AP article

May 29, 2009 - Takashi Hiraoka, a former Hiroshima mayor, stated - with regards to N. Korea's test - on May 26: "I have visited a number of nuclear testing sites, but even with underground testing, radiation is leaked. I am worried that the North Korean public may have been exposed to radiation." article

May 29, 2009 - '"Radioactive noble gases will seep out [from an underground test site] even if you contain the particles," says CTBTO spokesperson Annika Thunborg. "You can never contain it entirely."' article

May 28, 2009 - ITAR-TASS World Service - '..."The registered radiation background in Vladivostok, Nakhodka, Posiet, and Barabash fluctuates between nine to eighteen microroentgen per hour, with the norm being 30 mr/hr," Koridze said. In the event of nuclear tests, specialists expect a rise in the radiation background within the first three days after the test. Later on changes are unlikely. However, the monitoring of the radiological situation in Primorye will be carried on in an enhanced mode until May 31, Koridze said. The enhanced monitoring of the radiological situation in Primorye was launched on May 25, immediately following the announcement about the conduct of an underground test of a nuclear device in the DPRK.'

May 27, 2009 - 'The US government remains officially mum on technical details about the underground blast that took place Monday in North Korea. It could be days or weeks before radioactive gases from the underground test are detected and analyzed by US and allied intelligence.' - N Korea's bomb test 'troubling progress, The Daily Star

May 27, 2009 - Is North Korea shooting off missiles daily to thwart radiation detection? - 'The launches likely represent an attempt by Pyongyang to interfere with South Korean and U.S. efforts to detect the radioactive gases that a nuclear explosion emits.' more

May 27, 2009 - 'Released even by underground nuclear tests, the radionuclides would be carried around the northern hemisphere over the next few days and weeks by winds. ' - Blast had pulses racing, The Sydney Morning Herald

May 26, 2009 - 'Maritime Territory will not be exposed to radioactive fallout after the nuclear test in North Korea, the press service of the local meteorological centre said today. As estimated by Rosgidromet's [Federal Service for Hydrometeorology and Monitoring of the Environment], the air-mass trajectories from the test site "indicate possible transmission of radionuclides towards Japan in case of their emission and the absence of transmission towards Russia," the press service said.' Russia: Possible nuclear fallout from N Korea no hazard to Maritime Territory, Excerpt from Russian state news agency ITAR-TASS Vladivostok report

May 26, 2009 - Peace Clock in Hiroshima reset - article; visit our peace clock replica online

May 25, 2009 - NORTH KOREA CONDUCTS UNDERGROUND NUCLEAR TEST, ON SAME DAY AS SIMILARLY-SIZED U.S. NUCLEAR TEST IN 1953 - In the United States, fifty-six years ago today, Shot Grable was conducted at the Nevada Test Site. Grable was an atomic cannon test. The 15 kiloton yield nuclear device was shot from a 280mm cannon but only reached one-third of the goal altitude of 1,500 feet, where it created a mushroom cloud topping at 35,000 feet. According to Richard Miller's book "Under the Cloud," part of the radioactive mushroom cloud from Shot Grable moved northwest to Oregon and Washington and another section moved east, crossing New England within 24 hours. A violent thunderstorm dropped radioactive hail on Washington, DC. And another section moved over Idaho. In total, Grable fallout fell on 98 percent of the over 3,000 counties in the United States. All of the fallout in the U.S., due to unique meteorological conditions, happened within 24 hours of the test. Grable increased the radiation on the ground in dozens of U.S. counties up to 1,000 times the current EPA threshold of 0.2 microcuries per square meter. It was one of 100 aboveground tests conducted at the Nevada Test Site from 1951 to 1962 that cumulatively added 150 million Curies of radioactivity into the environment.

Idealist's public document archives: 1. 2.

U.S. NUCLEAR tests: 128 A + 899 U in NV,
1 A in NM, 10 U (in NM, CO, AK, MS, central NV),
100+ A, U in Pacific, 3 A in S. Atlantic
(A=aboveground; U=Underground)

'The greatest irony of our atmospheric nuclear testing program is that
the only victims of U.S. nuclear arms since World War II have been our own people.'
- Forgotten Guinea Pigs Report, 1980

In 1986, the U.S. Dept. of Energy used the cover of the Chernobyl fallout cloud over the United States to release huge amounts of radiation into the air from a failed underground Nevada nuclear test. It was called Mighty Oak.

Did global fallout cause massive mutations that may explain disorders like autism?

learn more on our global fallout page

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20 Radioactive Dangers We All Face
1. Nuclear reactors crashing on Earth from space and fallout from: 2. Pacific nuclear testing 3. the Nevada Test Site 4. High-altitude nuclear tests 5. Project Rulison 6. Mighty Oak nuclear test 7. North Korea's nuclear tests 8. Global nuclear testing 9. 'Project 57' (Area 13) 10. Trinity, WSMR & Steel	11. Hanford & INL & LANL 12. Nuclear Power 13. DTRA's Divine Strake's babies 14. Fallout resuspension: Milford Flat Fire 15. Australia's fallout and duststorms 16. Hiroshima & Nagasaki -and- 17. Low-level radiation impacted viruses 18. Radioactivity in drywall (dust) 19. Nuclear waste transport 20. Greenham Common