Risk Assessment for Rare EventsApplication to terrorism: talk at Duke University

April 23rd 2008Richard Wilson

Mallinckrodt Research Professor of PhysicsHarvard University

Physicists are used to rare events:they occur with calculated probability

Molecules reaching the surface of a liquid usually turn back.

A few (fast ones) evaporate. This leads to vapor pressure (Clausius – Clapeyron)

Meteorites hit earth with roughly calculated frequencyrisk of extinction - 10-8/yr

Individual risk of Death - 5 x 10-7/yr

Rare Nuclear Power accidents first studied by physicistsAdvisory Committee on Reactor Safeguards –

Teller, Wigner, and Feynman

Before 1970, only accidents less than the MAXIMUM CREDIBLE ACCIDENT

were consideredThe landmark Reactor Safety Study (WASH 1400) in 1975

was chaired by a physicist (Rasmussen)Looked quantitatively at the extreme events

(Low Probability; High Consequence)by a combination of EVENT TREES and FAULT TREES

First task:Define the problem.

Next task: break it into manageable component

partsfactorizable as much as possible

Nuclear Power was the first example

Simplified EVENT TREE for pipe break

Rate of Pipe Breaks F1Probability of ECCS (SF) failure P2Probability of Containment Failure P3Probability of wind blowing to City P4

IF INDEPENDENT

Overall rate = F1x P2 x P3 x P4FAULT TREE can be used to estimate

P2,P3, P4

GOOD BAD

F1 1/10,000yr 1/100yrP2 1/30 1/5P3 1/3 1/2P4 1/3 1/2

Overall 1/2.7million 1/2000

Are the probabilities coupled?A failure scenario which couples them is called a

Common Mode Failure

Fire or flood can couple the individual steps At Browns Ferry fire in a cable duct led to loss of control.

(solution: use redundant cable ducts)

The event tree enables us to focus on these correlations.Now every reactor has a detailed study

(Jargon - Probabilistic Risk Analysis -PRA)It enables the analyst to find weak points.

In the first PRA (Surry, VA) a simple change for about $50,000 reduced the calculated accident probability by a factor of 5

Industries now using Event Tree Analysis

1975 Nuclear Power WASH 1400;NUREG 75/014 1978 LNG: Keeney et al Techn. Rev. 81:64 1985 Oil refineries1985 Chemical plants2000 NASA2xxx Building Industry (not yet)Independence of steps not as easy as in nuclear power.

A saboteur can :take a nuclear engineering course

work at a nuclear plant as a “sleeper”

Then he can set off two bombs(1) To break a pipe and

(2) open a containment hole (3) when the wind is blowing to a city

If 6 terrorists act in concert it is easier

A saboteur (terrorist) can couple the different steps

Rasmussen said in 1978:“There is nothing a terrorist can do that

those clowns (operators at TMI ) did not do on their own”.

My response: A terrorist can increase the probability!

Especially a group of terrorists

World Trade Center 2001Steel Frame buildings must have the beams insulated to

stop bending in case of fire. The first steel buildings were more dangerous than wood ones.

Insulation used:1900 Concrete1960 Asbestos incl. mineral wool1970 Only mineral wool2010 Maybe material used in nose cones???

Who decides? Who knows?Examine FEMA report and later NIST report with jaundiced eyes

What is missing?

At WTC beams and links bent. WHY?Was the insulation there?

It was sprayed on dry, not wet. Did it stick?Did plumbers and electricians remove any?

DOES ANYONE KNOW?The consequence of WTC collapse

was more than 3000 deaths.It was a political change in the USA

Will there be a full, publicly available, study including high consequence low probability scenarios

before rebuilding?

Imagine what a terrorist might do: and

devise a system to make it hard for him to do it. 

Stop the event as early in the chain as possible

(dont let trouble spots fester)

Event Tree Analysis

Suggested Event Scenario

(1) Stop creation of terrorists

(2) Keep weapons out of hands of terrorists(3) Keep potential terrorists away from

sensitive places(4) Make ALL individual targets more secure

Stop a scenario as early in the event chain as possible

Fewer terrorists than targets!

What makes a terrorist?

The organized Al Quaeda of 2001 no longer exists(Scott Atran)

Now organization by internetMadrid bombing was a group from one area of Morocco

terrorists are like ordinary people

2001 terrorists: educated. Not religious(Marc Sageman: “Leaderless Jihad”)

Why more terrorist suspects in Europe than USA?Frustration with lack of integration?

Watch internet grouping

Known Terrorist Groups with Assumed reasons for Frustration

Tamil Tigers - Sri LankaIRA - Ireland

Hamas military wing - Palestine/IsraelHezbollah - Lebanon

Basque separatists - SpainTaliban – NW Pakistan

“If there is hope and you kill a terrorist you have one terrorist less

If there is no hope and you kill a terrorist you have 10 terrorists more”

(Israeli General: Also Yugoslav experience in WWII)

Some important Psychologists:

Lord John Alderdice (Northern Ireland)Marc Sagerman (Interviews since 9/11)

Scott Atran Baruch Fischoff (Case Western)

Step 2.Keep weapons out of the hands of

terrorists

Firearms are easily available. Even AK57s But

Atomic Bombs?Biological material?

Nerve gases?

Step 2 keep weapons out of the hands of terrorists.

Only limited possibilities for ordinary weapons - including AK47s

ESSENTIAL FOR NUCLEAR WEAPONSNot easy for chemicals or

biological materials

Important to prioritize“If you guard your toothbrushes as carefully as you guard

your diamonds You will lose fewer toothbrushes but

you will lose more diamonds!”JH Van Vleck (circa 1955)

Be careful with fissile material: IAEA records

Step 3.Keeping Terrorists at Arm’s length

Make it hard to enter the US keeping terrorists away from facilities

is where US is concentrating efforts

Inevitably conflicts with liberty and human rights 

USSR system of closed areas – (Chelyabinsk, Sverdlovsk)

no longer works   

Step 3

Importance of Secrecy As in military matters:

Strategic (long term issues) should be openTactics (short term issues) should be on a

“need to know”

I know, in general, where to fly an airplane to destroy a nuclear power plant, (not the

containment vessel)but on individual detail, I do not need to know

Step 4. Making Society Safer AEngineering and Industrial facilities

   Do not store a lot of fuel in one place near a lot of people in one place. (Wigner 1974)

Oil tanks and LNG facilities should be in remote areas.   (In 1848 London decided to keep Petroleum products 30

miles from London bridge in Canvey Island)

Terrorism and Sabotage already considered for nuclear power.

Look at every industry for high consequence scenarios

The following accidents happened naturally

A terrorist can make them happen more often!

(1)Substation failure in Naperville ILL shut down landing system at O'Hare (and cut off my son's E mail)

(2) Broken relay shut down NE electricity for 5 hours (1967)(3) Storm cut major transmission lines in France for 4 days

(4) 1944 at Clapton Sands off duty US soldiers shot at insulators and shut down the line to Naval base

(punishment was being sent to Utah Beach...)

IF:20 terrorist sharp shooters each chose a transmission tower

in a remote area and at noon each shot at an insulatorMAYBE AT THE SAME TIME

other terrorists release gunk in subway....

Anyone guess the consequence?

There are many more terrorists than there are dangerous facilities.

BUT if the facilities are protected, a terrorist may do not do anything

Physical protectionbe wary

Possible “easy” terrorist Actions

Anthrax released in a high explosive bomb upwind of city can kill more people than a plutonium bomb

Silver cyanide plating solution dumped in reservoir after filtration

(possible in Oxford in 1949)

Biological material released in subway

Emergency exits not used in USARhode Island Fire people did not use

Fire protection, etc must be practiced.

Andrea Doria in collision in calm weather in fog and sank in 3 hours

100 people diedBritish troopship with families sunk in 1/2 hour

engineer killed in explosion all others saved!

Step 4 – Making Life Safer B

B Biological Processes Reducing Natural Epidemics also trains people to

reduce the risk of biological terrorism

1919 Flu; 2005 SARS

In disease spread there are 2 crucial numbers:

(i) average number of people a single person infects ~ 2.5

(ii) time between infections ~ 10 days

Act promptly to reduce (i) from 2.5 to 0.99At least 60% of all people must cooperate

(Successes - small pox;

Wash handsWear face mask especially infected people (Japan)

Don't go to work/school or travel if feverQuarantine; need for societal agreement

In community:radio temperature to central place to identify a

cluster of high fever. Then start more drastic action promptly

1918 Influenza: the Mother of All Pandemics

This is not emphasized by Public Health Professionals

Jeffery K. Taubenberger and David M. Morens Armed Forces Institute of Pathology, Rockville, Maryland, USA; and National Institutes of Health, Bethesda, Maryland, USA

CDC Health Topics Vol. 12, No. 1January 2006

Fails to emphasize the importance of immediate action.

Airline Pilots will now resist a hijackingBar cockpit doors

Maybe set to control from ground or automatic

Use emergency exits regularly“The public may leave at the end of each

performance by all exit doors and at that time the doors shall be open”

Lord Chamberlain's regulations, UK

Easy access to first aid boxesIn a recent inspection in Boston, they were

locked up and noone had the key!

Few plans for a major fire at WTC? (FEMA report instructive for what it missed out)

Insulation not tested for durabilityFire and initial impact destroyed all safety

mechanisms (Common mode failure not foreseen!)

Helicopter fire fighters?Protect buildings by cables from

towers or balloons?

The crucial questions in terrorism is the coupling between the steps.

A terrorist will choose to attack unprotected facilities and there are

many

Crucial Importance of Readiness for Response

If a terrorist knows that there will be a quick and intelligent response

it will be less attractive

Inspect the insulation of all buildings over 50 stories high.

(expensive but possible;

e.g. apply a heat source to steel in one location and compare the

temperature - time profile with calculation)

Anthrax in small amounts make only a local problemIrradiate all mail at sorting offices (Co60 or Cs137)

Anthrax spores released in a small HE bomb up wind can kill more people than a hydrogen bomb

poisoning water supplies? Emergency purification?

Some terrorists are now educated. Also some act in concert

    Sabotage and terrorism are unfortunate facts of life.

  They will be with us until the end of

the human race. 

We must not let terrorism distort our lives.

Other risks are bigger.Car accidents:

45,000/yr vs. 3,500 onceDrugs destroy society more

Security vs. FreedomOur human rights are what makes life worth living.

“If you still want to belong to an organization dedicated to killing Americans, there’s always the tobacco lobby.”

Alex Gregory, Cartoonbank.com