Nuclear Weapons: Sources of Strength or Vulnerability?  

Physics Dept. CCNY, 25 April 2017Aron M. Bernstein

Physics Dept., Lab For Nuclear Science MIT

Some say nuclear disarmament is utopian, premature, a dream.I say the illusion is that nuclear weapons provide security”

UN Secretary-General Ban Ki-moon. Seoul, Oct. 2012

•  current dangers, pathways to nuclear war?•  nuclear weapons, Hiroshima, atomic scientists•  force deployment; deterrence, war by accident?•  NPT, Iran Agreement, N. Korea•  maintenance/modernization •  outlook- citizen education, participation

Why think about nuclear weapons?

•  Not used since 1945 -Hiroshima and Nagasaki (nuclear taboo)•  No danger since 1991-Soviet Union collapsed. •  deterrence works (peace through strength) “If you want peace prepare for war” (Roman)•  let's work on more important issues like climate change….

Why think about nuclear weapons?

•  Not used since 1945 -Hiroshima and Nagasaki (nuclear taboo)•  No danger since 1991-Soviet Union collapsed. •  deterrence works (peace through strength) “If you want peace prepare for war” (Roman)•  let's work on more important issues like climate change….

dangers are increasingBulletin of Atomic Scientists “Doomsday Clock” reset to Cold War era levels

cold war legacy: concepts, weapons, deployment modes•  US, Russia have 900 weapons ready to fire tension increasing Ukraine, Crimea, Syria modernizing weapons, delivery systems arms race•  proliferation: India, Pakistan, N. Korea

It is two and a half minutes to midnight

2017 Doomsday Clock Statement

Science and Security BoardBulletin of the Atomic Scientists

Editor, John Mecklin

IT IS TWO AND A HALF MINUTES TO MIDNIGHT©

Nuclear Weapons Education Initiative

participate in education, public discourse

•  give a few lectures in undergraduate courses •  could be part of a modern physics, science, history, politics,…course•  give a focused course on nuclear weapons (preferably interdisciplinary) •  objective, factual, discussion of the issues•  this is not a call to politicize the classroom•  it is a call for creativity and moral responsibility•  informal network of interested faculty members/students•  students can request courses/information from the faculty

How do weapons work?Critical Mass ≈10kgm 235U, ≈ 6kgm 239Pu

> 2 neutrons per fission

Nuclear Weapons Physics: order of magnitude estimatefissionable material 235U, 239 Pu

completely fission 1 kgm -> 20kTon explosion

blast lasts ~ 1 u sectemperature > interior of sun

critical mass 15 Kgm (U) , 5Kgm (Pu)

1/15/13 4:47 PMNuclear Weapons - basic technology concepts [UNC]

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escape and a chain reaction is not possible; such a mass is termed subcritical. Ifthe neutrons generated exactly equal the number consumed in subsequentfissions, the mass is said to be critical. If the mass is in excess of this, it istermed supercritical.

Fission (atomic) weapons are simply based on assembling a supercritical mass offissile material quickly enough to counter disassembly forces.

The majority of the energy release is nearly instantaneous, the mean time fromneutron release to fission can be of the order of 10 nanoseconds, and the chainreaction builds exponentially. The result is that greater than 99% of the veryconsiderable energy released in an atomic explosion is generated in the last few(typically 4-5) generations of fission -- less than a tenth of a microsecond.*

This tremendous energy release in a small space over fantastically short periodsof time creates some unusual phenomena -- physical conditions that have noequal on earth, no matter how much TNT is stacked up.

Plutonium (239Pu) is the principal fissile material used in today's nuclearweapons. The actual amount of this fissile material required for a nuclear weaponis shockingly small.

Below is a scale model of the amount of 239Pu required in a weapon with theforce that destroyed the city of Nagasaki in 1945:

In the Fat Man (Nagasaki) weapon design an excess of Pu was provided. Most ofthe remaining bulk of the weapon was comprised of two concentric shells of highexplosives. Each of these was carefully fashioned from two types of explosiveswith differing burn rates. These, when detonated symmetrically on the outermostlayer, caused an implosion or inward-moving explosion.

The two explosive types were shaped to create a roughly spherical convergentshockwave which, when it reached the Pu 'pit' in the center of the device, causedit to collapse.

The Pu pit became denser, underwent a phase change, and became supercritical.

A small neutron source, the initiator, placed in the very center of this Pu pit,provided an initial burst of neutrons -- final generations of which, less than a

Hiroshima Aug. 6, 1945 15kTons ~ 2% efficient ≈35% killed, ½ first day, blast, burns, radiation Modern bombs are ≥  10 times more powerfulhigh altitude bomb-EMP could destroy all US electronics one bomb, one city, many bombs - nuclear winter

We Meant so Well

I.I. Rabi at Los Alamos on the 40th anniversary of Trinity

•  First we were afraid that Hitler would get the bomb

•  Then we were afraid that we would get it

Debate: Utility of Nuclear Weapons

Pro•  Ended war in Japan•  Saved casualties in

WW2•  Prevented (deterred)

WW3 US/USSR

Con•  not necessary; were

the first step in the cold war

•  Needlessly killed Japanese civilians

•  European war was not likely without nuclear weapons

Expectations about the bomb: 1945•  Atomic Scientists(Oppenheimer,Bohr,Franck, Szilard) so terrifying that war could be ended•  genocidal weapons•  common problem that mankind should solve together no secret, no monopoly, no defense international control required One World or None•  Politicians (Churchill, Roosevelt, Stalin,..) a powerful tool to influence (coerce) others

Expectations about the bomb: 1945•  Atomic Scientists(Oppenheimer,Bohr,Franck, Szilard) so terrifying that war could be ended•  common problem that mankind should solve together no secret, no monopoly, no defense international control required One World or None•  Politicians (Churchill, Roosevelt, Stalin,..) a powerful tool to influence (coerce) others

neither was fully correct•  small coercive influence during US monopoly (45-49) USSR took over Poland, Czechoslovakia China entered the Korean War •  after NPT (1970) deterrence, abhorrence ⇒ non-use (nuclear taboo)

number of warheads cold war

N. Korea ~5-10

Do we need to improve our nuclear arsenal?

US Trident II Submarine

•  24 missiles x 4 = 96 warheads•  could destroy that many targets •  warheads;100kT, 475kT (Hiroshima ~15kT)•  delivery time 15-30 min•  total explosive power > 10MT•  total allied bombing in WWII ~ 3 MT•  could cause worldwide nuclear cooling, famine

•  US 14 subs, England 4 (12+2 at sea)

Can Nuclear War Happen?

not rationally- no country wants itbut tense situations can get out of control

remainder of talk will focus on this

Launch on Warning: accidental nuclear war?

•  US and Russia have ~ 900 missiles on alert status•  delivery times ~15 (30) min SLBM (ICBM) based•  decision times ~ 10 min•  first strike capability •  false alarm (cyber?) -> mutual destruction global nuclear winter for ~ decade •  US president has nuclear black box 24-7•  probability of error not negligible (complex systems)•  each side vulnerable to the other’s system•  Russian early warning system less robust•  need public education, pressure to change

Other Possible Pathways to Nuclear War

•  escalation of a conventional war •  Pakistan and India have ~ 100 weapons worldwide nuclear winter for several years.

•  North Korea 5 nuclear weapons tests, developing delivery missiles threatens to use them- could get out of control    •  complacency: nuclear weapons will never be used” no urgency to solve problem

Luck has saved us on many occasions

•  1962 Cuban Missile Crisis -Soviet nuclear submarine commander did not fire his nuclear weapons.

•  US false alarm Nov. 1979 warning of 200 Soviet missiles on their way•  1983 a false alarm in the Soviet early warning system indicated a US

missile attack; Soviet officer on duty did not report this to his superiors, preventing a nuclear war; similar incident on US side 1983-L. Perroots

•  many incidents-nuclear weapons dropped by accident-did not detonate (Schlosser- Command and Control)

•  hacking of early warning system? •  do nuclear weapons provide security or endanger it?

Nuclear Weapons Maintenance•  Last US test 1992 ( No. 1132)•  1994 Science Based Los Alamos Stockpile Stewardship

maintains weapons without exploding them: experiments test components, supercomputers model weapons

•  enhanced safety, reliability•  Life extension, annual assessment

Modernization [arms race-decreased security?]

•  30 to 50 year plans to modernize all strategic delivery systems •  new Start level-although Pentagon certified 1/3 reduction OK•  cost ~ $18b/y 2021 to 2035 in FY 2016 dollars, increase of ~ 3% to 7% of military budget•  total cost of ~ $1T over the next 30 years ($90 million/day)•  improved accuracy: B61-12 bomb (bombers), improved fuzing

Initiation of nuclear war

“Nuclear Button”National Security State

•  set up 1947; cold war, •  atom bomb required quick action

•  daily presidential security briefing Obama participated, not Trump

•  effect on president’s policy?

nuclear  briefcase  

Nuclear Non-Proliferation Treaty (NPT) 1970•  189 countries •  P5 :US, Russia, China, England, France committed to disarm; no time schedule: article 6•  resolution to ban nuclear weapons-UN •  Iran: 2015 agreement•  outside treaty: India, Pakistan, Israel•  N.Korea: joined, withdrew: 5 tests

   N. Korea serious problem, not a crisis

 permanent war footing,  spends ~25% of GNP on military army 1.1 Million ~ 15%   Seoul -1.1 million people -35 miles from N. Korea- ~13,000 artillery thereKorean war 1950-53 armistice, no peace treaty

  5 nuclear weapons tests •  first (2009) ~0.5kT detected international monitoring stations •  2 in 2016•  accelerated ballistic missiles program (26 in 2016). •  violation of UN Security Council resolutions.

Obama policy “strategic patience”- sanctionswaited for N. Korea to change course did not work-sanctions evaded, capabilities increasing Trump policy: get China to solve problem, threaten force

direct diplomacy needed: carrots and sticks start with freeze

   

negotiations with N. Korea Zigs and Zags

N. Korea signs NPT 1985. safeguards started in 1992serious problems emerged with IAEAAgreed framework 1994- 2002; N.Korea shut down its reactor, to be replaced mutual accusations of not carrying it outJan. 2003: N. Korea withdraws from NPTfirst bomb test 2006 ≈ 0.5 kT (fizzle?)- detected CTBT0 negotiations in 2008, 9 didn’t succeed

US regarded agreement as freezing weapons development, N. Korea wanted diplomatic recognition, normalization and aid

N.Korea background informationChina does not want a failed nuclear weapons state on their border90% of the trade that North Korea has is with ChinaUS THAAD (Terminal High Altitude Area Defense) missile deployment- problem with China

N. Korea made recent overtures-ignored        

“Reckless Leader Nuclear Strategy Theory” (Thomas Schelling)leader cannot be counted on not to initiate nuclear war

Nixon-Kissinger tried this to end Vietnam War secret operation Giant Lance, Oct. 10, 1969- placed U.S. nuclear assets on high alert bomber squadron with nuclear weapons flew patterns near USSR. didn’t work and was terminated

What happens when 2 leader try the same tactic??Kim Jong-un has been threatening to use nuclear weapons for years Trump – deterrence through threats “all options are on the table”

weapons-grade plutonium, for 15 years, and it does not intend to do so thereafter.

Intrusive MonitoringThe agreement will put in place enhanced international monitoring and accountancy to promptly detect and deter Iranian noncompliance. The agreement will set up a multi-layered system to monitor and inspect every aspect of Iran’s nuclear supply chain and fuel cycle, including continuous monitoring at some sites for 20–25 years. Other elements, including access to a wider number of nuclear sites—notably centrifuge manufacturing sites—and inspections on short notice under the terms of Iran’s additional protocol, will be permanent. Inspectors will have access to any site, anywhere, including military sites, if there is evidence of suspicious nuclear activities. A special adjudication commission will ensure disputes are settled within 24 days; this will ensure prompt access when necessary. With sufficient resources, the International Atomic Energy Agency will be able to verify Iran’s commitments effectively.

Incentives for Iranian Follow-ThroughThe structure of the nuclear deal gives Iran incentives to follow through on its commitments. No sanctions relief will be granted until Iran has taken steps to limit its uranium-enrichment program, convert the Arak heavy- water reactor, provide required trans-parency, and give the IAEA the infor-mation needed to resolve questions about about past activities with

Nov.2012

Nov. 2013

Nov.2014

June 2015

8,000 kg

6,000

4,000

2,000

0

Source: JCPOA

Capping Iran’s LEU Stockpile

possible military dimensions. For 10 years, if Iran violates the agreement, UN sanctions will snap back into place and the United States and the inter-national community will have the time necessary to respond. Though the UN Security Council’s previous prohibition on nuclear- capable missile work will end after eight years, mis-siles without nuclear warheads are a significantly lesser threat.

No Deal, No LimitsThe final P5+1 agreement with Iran should not be judged on how it ad-dresses any single element of Iran’s nuclear program. Instead, policy- makers should assess its overall impact on reducing Iran’s nuclear capacity and improving international monitoring and verification. There is no better deal on the horizon. Congressional efforts to block implementation would unravel the deal, undermine global support for the existing sanctions architecture, and allow Iran to accelerate its nuclear program and escape more-intrusive in-ternational monitoring. The risk of an Iranian nuclear weapon and a military conflict over the issue would grow. 

10 Years

Implementation begins 5 years 10 years 15 years 20 years 25 years

Key Restrictions Will Last Well Over a Decade

The Arms Control Association is an independent, membership-based organization dedicated to providing authoriative information and practical policy solutions to address the dangers posed by the world’s most dangerous weapons. For more information,

visit www.armscontrol.org.

Implementation of additional protocol, commitment not to reprocess plutonium, NPT obligations

Continuous surveillance of uranium mines and mills

Continuous surveillance of centrifuge production areas

LEU stockpile capped at 300 kg, no enrichment at Fordow, no new heavy-water reactors

Limit of 5,060 IR-1 operating centrifuges

Very limited R&D on advanced centrifuges

Iran Agreement(2015)  

•  blocks  239Pu  path  to  bomb  (need  ≈  4Kgm  )              unfinished  Arak  reactor  reconfigured:  6  Kgm  Pu/y  -­‐>  1  Kgm/y                                                                                                                                  no  weapons-­‐grade  plutonium,  ship  all  spent  fuel    (Permanent)  •  no  addiGonal  heavy  water  reactors,  will  not  reprocess  fuel-­‐15  years.    

•  but  US  poliGcs  prevenGng  taking  full  advantage  of  this  opportunity  

~1/2 bomb

extends breakout time to > 1y

Obama’s Nuclear Weapons Legacy?

•  April 2009 Prague speech –abolish nuclear weapons•  New Start Treaty (Feb. 2011)-agreed to modernize arsenal •  improved Nuclear Security (Summits)•  tried to engage Russia in further steps (failed)•  Iran agreement (2015)•  ~1000 nuclear weapons still on launch on warning (US, Russia)•  N. Korea•  did not declare a no first use policy•  did not get the CTBT(Comprehensive Test Ban Treaty) ratified

Outlook; some reasons for guarded optimism

•  no nuclear war since 1945 deterrence, nuclear taboo, luck•  despite strains, NPT working reasonably well•  CTBO in operation: detected ~0.5kT N.Korean test•  budget constraints in Russia and US may lead to

nuclear force reductions•  world wide discussion of zero nuclear weapons•  humanitarian renunciation of nuclear weapons (UN

general assembly)•  public education, opinion counts!

Plenty of Work to Reduce Danger of Nuclear War

•  take weapons off hair trigger alert•  Iran agreement -follow through, don’t scrap it!•  N. Korea-negotiations, not threats, involve China •  US-Russia-reduce weapons to ~1000 including tactical, •  stockpile stewardship program (maintain, not modernize) •  use budget constraints to improve nuclear weapons policy•  make NPT more effective prod US-Russia for reduction timetable•  US discretionary budget > 50% military

•  scientists/academics: nuclear weapons education•  we need help with education project

11/29/16, 3:25 PMdiscretionary_spending_pie,_2015_enacted.png 1,003×915 pixels

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 ~  $600 Billion> next 7 countries

Will Trump rip up the Iran agreement as he promised during the election campaign?

“the stupidest deal of all time”

It is not just a US-Iran agreementthe rest of the P5+ 1 want to keep itthey are lifting sanctions and doing business

James Mattis, nominee for defense secretaryNYT, Dec. 2 ”Despite his tough stance on Iran.. he thinks that tearing up the agreement is favors keeping the agreement would hurt the US and favors working with allies to enforce it’s terms”.        

Bulletin of the Atomic Scientists

!(2.5min) 2017

Bulletin of the Atomic Scientists

!(2.5min) 2017