What ‘sniffer’ planes can tell us about North Korea’s nuclear tests



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Boeing WC-135 Constant Phoenix “sniffer plane” used to monitor radioactive emissions from nuclear bomb tests.
US Air Force/Staff Sgt. Christopher Boitz

Kaitlin Cook, Australian National University

On Sunday, North Korea claimed it had completed its sixth nuclear test – a hydrogen bomb.

This test was performed underground by the notoriously secretive regime. So, how can the international community know the state news agency was telling the truth?

The 6.3 magnitude tremor tells us there was an explosion Sunday. But to know this was a nuclear test, we have to detect the signature of a nuclear explosion.


Read More: Trump can’t win: the North Korea crisis is a lose-lose proposition for the US


Nuclear weapons either produce energy through nuclear fission (fission bombs) or a combination of fission and fusion (thermonuclear or hydrogen bombs). In both cases, nuclear reactions with neutrons cause the uranium or plutonium fuel to fission into two smaller nuclei, called fission fragments. These fragments are radioactive, and can be detected by their characteristic decay radiation.

If we detect these fission fragments, we know that a nuclear explosion occurred. And that’s where “sniffer” planes come in.

Nuclear fission and fusion.

Enter ‘sniffer’ planes

Since 1947, the United States Air Force has operated a nuclear explosions detection unit.

The current fleet uses the WC-135 Constant Phoenix. The aircraft fly through clouds of radioactive debris to collect air samples and catch dust. By measuring their decay, fission fragments can be detected in minute quantities.

The crew are kept safe using filters to scrub cabin air. Radiation levels are monitored using personal measuring devices for each crew member.

A WC-135 Constant Phoenix from the 45th Reconnaissance Squadron taxis in on the flightline.
US Airforce/Staff Sgt. Christopher Boitz

Sniffer planes like Constant Phoenix can be rapidly deployed soon after a reported nuclear test and have been used to verify nuclear tests in North Korea in the past.

This year, Constant Phoenix has reportedly been deployed in Okinawa, Japan and has had encounters with Chinese jets.

On the ground, the Comprehensive Test Ban Treaty Organisation (CTBTO) operates 80 ground-based monitoring stations across the globe that constantly monitor the air for fission products that have dispersed through the atmosphere.

Japan and South Korea operate their own radiation monitoring networks. These networks will also presumably be looking for signatures of the latest North Korean test.

CTBTO radiation monitoring system.

What can fission fragments tell us?

When a nuclear test occurs underground, the fission fragments are trapped except for noble gasses.

Because noble gasses don’t react chemically (except in extreme cases), they diffuse through the rock and eventually escape, ready to be detected.

In particular, some radioactive isotopes of the chemical element xenon are useful due to the fact these isotopes of xenon don’t appear in the atmosphere naturally, have decay times that are neither too long nor too short, and are produced in large quantities in a nuclear explosion. If you see these isotopes, you know a nuclear test occurred.

Something happened during this test that has people excited — there was an additional magnitude 4.1 tremor around eight minutes after the initial tremor, according to the United States Geological Survey. Among other things, this may indicate that the tunnel containing the bomb collapsed. If this happened, then other fission products and other radioactive isotopes could escape as dust particles.

This might have been accidental or deliberate (to provide proof to international viewers), but in either case, we may learn a lot, depending on how fast the sniffer planes arrived and how much dust was released.

For example, by looking at the probability of seeing fission fragments with different masses, the composition of the fission fuel could be determined. We could also learn about the composition of the rest of the bomb. These facts are things that nuclear states keep very secret.

Crucially, by looking for isotopes that could only be produced in a high intensity high energy neutron flux, we could suggest whether or not the bomb was indeed a hydrogen bomb.

What can’t they tell us?

The amount of information a sniffer plane can determine depends on how much material was released from the test site, how quickly it was released (due to nuclear decay) and how rapidly the sniffer plane got into place.

But fission fragment measurements probably can’t tell us whether the bomb tested was small enough to fit on an Intercontinental Ballistic Missile (ICBM). After all, it’s easy enough for North Korea to show a casing in a staged photograph and blow up something else.


Read More: North Korea panics the world, but ‘H-bomb’ test changes little


Whether or not North Korea has a thermonuclear device that is capable of being mounted to an ICBM is a question weighing heavily on the minds of the international community.

The ConversationSniffer planes and the CTBTO network will be wringing all of the data they can out of the debris in the atmosphere to help the world understand the nuclear threat from North Korea.

Kaitlin Cook, Postdoctoral Fellow, Department of Nuclear Physics, Australian National University

This article was originally published on The Conversation. Read the original article.

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MEDICAL SYSTEM IN GAZA STRIP NEARING ITS COLLAPSE


The latest reports coming out of the Gaza Strip indicate that medical personnel are having difficulty reaching the wounded and that the collapse of the medical system is imminent. Church officials are calling for a cease fire to treat the wounded, reports Catholic News Agency.

According to Caritas Internationalis, a network of 162 aid agencies which helps provide primary medical services in Gaza, its efforts to help the wounded are being severely hampered by the war.

Caritas’ president, Cardinal Oscar Rodriguez Maradiaga, has issued a call for an immediate cease fire, saying, “Caritas and our Catholic Church partners in the Holy Land call for an immediate ceasefire to enable the sick and wounded to be treated. Innocent people are suffering because aid agencies cannot reach them due to the Israeli military action.

“Caritas calls for action from the USA, the EU, and the international community on pressing for an immediate ceasefire to create the necessary environment in Gaza for aid agencies to be able to care for the wounded. War cannot be justified by either Israel or Hamas. Arguments over proportionality are morally repugnant when we are talking about the lives of innocent children.”

The latest figures show 87 Palestinian children have been killed in the Israeli attacks.

Caritas’ Jerusalem Secretary-General Claudette Habesch offered more details about developments on the ground. “Our staff in Gaza are witnessing a collapse of medical services. People are dying in their homes because they can’t get treatment. There are 2,053 hospitals bed sin Gaza and 2,500 people wounded by the Israeli bombardment. Doctors say they lack bandages and antiseptic.”

The Israeli offensive against Gaza began after the Palestinian region’s ruling Hamas party made continuous rocket attacks on southern Israel, citing Israeli raids and blockades.

Israeli tanks, planes, and ground forces continued their attacks Sunday night. According to Reuters, at least 541 people have died in the 10-day offensive.

Israel had occupied the Palestinian enclave in Gaza from 1967 to 2005.

Report from the Christian Telegraph