What does it take for the DPRK to

What does it take for the DPRK to be a nuclear threat? Jerry Peterson Department of Physics University of Colorado Jerry. Peterson@Colorado. edu

There is a secret to nuclear bombs!

The Secret to the Atomic Bomb? That’s not it.

The Secret to Nuclear Bombs They work! Plan A Plan B The Super

Hiroshima Plan A Nagasaki Plan B

Ground zero of the first Soviet A-test, August 1949. Plan B

Proliferation • Currently: USA, Russia, United Kingdom, France, PR China, India, Pakistan, North Korea, (and Israel) • Have thought about it: Canada, Sweden, Switzerland, Brazil, Argentina… • Have given them up: South Africa, Kazakhstan, Ukraine, Belarus • Active programs? Iraq, until we ended it. Iran?

Uranium is 0. 7% 235 U and 99. 3% 238 U neutron Excited nucleus, shaking Two fission fragments and 2. 4 neutrons Like charges repel—the origin of heat energy

Fission, just like a lava Lamp

The hardest part of getting a nuclear bomb is the material “Front End”- obtain 235 U (HEU=at least 80%) by exactly the same methods used to make Low Enriched Uranium (LEU) for power plants (typically 3 -4%) from natural uranium, 0. 7% of which is 235 U. “Back End”- obtain 239 Pu from Spent Nuclear Fuel by chemical reprocessing.

The plutonium route-Plan B • Construct a nuclear reactor, operating from the fission of 235 U. The operation of the reactor can be monitored by satellite. • Allow the excess neutrons available from this fission to capture on abundant 238 U to breed 239 Pu. (arithmetic: 238+1=239) • Separate the plutonium and uranium by ‘reprocessing’ chemistry, which releases radioactivity that can be sensed. • Create a fission bomb from this material.

DPRK summary • Began construction of nuclear reactors and associated technology from late ‘ 50’s, Yongbyon reactor operational 1986, making ~6 kg Pu/year using natural uranium. • Signed Non. Proliferation Treaty 1985—allows peaceful development • Withdrew from the NPT on 2003, and expelled IAEA inspectors in 2002. • Known to be developing nuclear bomb technology, via the plutonium route= Plan B. • Yongbyon components destroyed 2008, restarted • Evidence of uranium enrichment 2010 (Pakistan), Plan A • Lots of uranium ore 32, 000 tons of uranium

The context • NPT • US removed all nuclear weapons from Korea in 1991, in ROK since 1958, up to 950! In 1967. • Six Power talks—not just nuclear • Agreed Framework— Freeze plutonium program, in return for fuel oil and a promise of two LWR for power. • LWR concrete poured 2002, suspended.

You can’t hide any significant nuclear effort. • Satellite images, including heat sources • Seismology • Radioactivity—very sensitive and specific. • Laws of physics—extrapolations.

Yongbyon

Yongbyon facility

Now operating again S. Hecker

Test the device As we did in 1945. First (underground) 2006, sensed by seismology. A ‘fizzle’, but enough radioactive leakage to sense. Second one-2009, a few kilotons of TNT equivalent, but no leakage. Number 6 -September 2017

#6 --The ‘Super’? A hydrogen bomb uses a fission bomb ‘trigger’ to initiate fusion reactions among isotopes of hydrogen, for an unlimited yield. The trigger supplies enough pressure and temperature to allow two positive hydrogen nuclei to react.

But-like charges repel !

Future? Inventory— 20 -40 kg Plutonium 200 -450 kg HEU -enough for ~20 -25 weapons Production for ~6/7 weapons per year S. Hecker/ Bulletin of the Atomic Scientists

How big was #6? 3 September 2017 Richter 5. 7=5. 4 k. T Richter 6. 3=42. 5 k. T (Hiroshima 14 k. T) (convertalot. com/earthquake power calculator. htm) Hecker-perhaps 100 k. T

Ivy Mike 10 Mt “Science seems ready to confer on us, as its final gift, the power to

Nuclear Bomb Effects, by Testing Surface, air, underground, undersea, in space USA— 1054 The effects are experimentally known! Brian Toon, the expert