Radiological Terrorism and Public Health Lecture 17: Transportation Accidents, Power Plant...

Radiological Terrorism and Public HealthLecture 17: Transportation Accidents, Power Plant Incidents,and the Nuclear Threat

Steffan Puwal, PhD

Source: FEMA Emergency Management InstituteRadiological Emergency Management

Radiological Transportation

•Millions of shipments of radioactive material are accomplished without incident in the US every year▫Most of these shipments are

Nuclear plant fuel Weapons and weapons material Hospital waste Lab and research material Commercial products

Industrial Packaging (IP)

•Packaging designated Industrial Packaging (IP) contains LSAs and CSOs▫low specific activity (LSA) material is a

small amount of radioactive material within a much larger amount of non-radioactive material (such as smoke detectors)

▫Surface Contaminated Objects (SCOs) are non-radioactive objects with a surface contaminated by radioactive material (such as pieces of hospital equipment)

Industrial Packaging (IP)

•When LSAs and CSOs are transported, they must be shipped in packaging well secured to prevent leakage▫The packaging will carry the designation

IP-1, IP-2, or IP-3 depending on the integrity of the shipping container

▫Must carry the label “RADIOACTIVE-LSA” or “RADIOACTIVE-CSO” depending on the material being shipped

Shipment of Radioactive Material• Limited Quantity Shipments

▫Quantities of radioactivity and levels of surface radiation exposure are very low

▫ Includes certain medical diagnostic kits▫Potential radiation hazard is very low, but in the

event of an accident radioactive material will be release

▫Do not require a “radioactive” designation on shipping

▫Limited Quantity Shipments for the US Postal Service are usually 1/10 the radioactivity of a private carrier’s allowed limits

Shipment of Radioactive Material• Type A Packaging

▫The majority of radioactive material shipments▫Greater activity allowed in Type A than allowed in a

“limited quantity” package, but less than Type B▫Designed to withstand stresses of non-accident

conditions (rough handling, etc.)• Type B Packaging

▫More highly radioactive shipments such as radiography sources

▫Designed to contain their contents under accident conditions including drop, puncture resistance, thermal and water immersion stresses

Information Sources

•In responding to a shipping accident or an attack on material in transit, several sources of information are available to the first responder▫Package labels▫Package markings▫Vehicle placards▫Shipping papers

Package Labels•Nearly all packages containing

radioactive materials must carry the label “RADIOACTIVE” and carry the tri-blade radiation symbol

Packaging Labels

•There are 3 basic labels used to identify radioactive materials▫Radioactive White-I▫Radioactive Yellow-II▫Radioactive Yellow-III

Radioactive White-I• Used on

packages with a maximum dose rate of 0.005 mSv/hr (0.5 mR/hr) on any exterior surface

• Measurement made on contact with the surface

White

Black

Black

Red

Radioactive Yellow-II•Maximum

on-contact surface measurement of 0.5 mSv/hr (50 mR/hr)

Black

Black

Yellow

Red

Radioactive Yellow-III•Maximum

on-contact surface measurement of 2 mSv/hr (200 mR/hr)

Black

BlackRed

Yellow

Package Marking

•Most packaging also carries a 4 digit U.N. Identification Number with a specific set of response instructions (Hazmat and Fire) as outlined in the U.S. Department of Transportation’s Emergency Response Guidebook

Vehicle Placards

•Placards are signs on the outside of the vehicle

•Any vehicle carrying a RADIOACTIVE YELLOW-III package must have a RADIOACTIVE YELLOW-III placard, for example

Shipping Papers

•The content of delivery, identifying the point of origin and destination as well as the contents and activity must be listed on shipping papers readily accessible to the driver of the truck, chief engineer of the train, or pilot of the ship/plane

•Shipping papers contain all information of the placard plus additional information on the chemical form of the material (such as “Flammable Liquid”)

On-Scene Accident Response

•Priorities should be▫Help▫Notify▫Isolate

•As we have seen, unbroken packages in normal shipping never have a surface radiation level exceeding 1000 mR/hr, so helping an accident victim should never be delayed on the basis of concern over exposure to first responders

On-Scene Accident Response•Authorities should be notified• If possible, information contained on the

placards, shipping label, or shipping papers should be relayed

•The area should be isolated to prevent additional exposures

•Areas are usually cordoned off by first responders; this should never hold people in the area, increasing their exposure time

Nuclear Power Accidents

Nuclear Power

•Virtually all commercial nuclear power reactors in the United States are either PWRs or BWRs (pressurized or boiling water reactors)

Nuclear Power•The water used to cool the condenser is

slightly warmer after use. For this reason, a cooling tower is sometimes used to prevent a harmful spike of temperature.

Nuclear Power

•For a September 11 – style attack, the cooling tower presents the most visible target

•However, no nuclear material is contained within the cooling towers▫A plane crash, tornado, or earthquake that

takes out the cooling tower alone will not result in the release of radioactive material

Nuclear Power

•Control rods are neutron absorbers. Inserting the control rods kills off the nuclear chain reaction and shuts down the reactor – we say we scram the reactor

Fuel•Ceramics have very high melting points•For this reason, UO2 (uranium dioxide) ceramic

pellets serve as the fuel▫Typically cylindrical in shape, ½ inch high and ½

inch in diameter▫Stacked end-to-end to form a 12 foot long fuel

rod▫The fuel rod is enclosed by a metal fuel cladding

The fuel cladding is a first line of containment, containing the mass yield of the uranium fission within the cladding of the rod

Fuel

•A number of fuel rods are grouped side-by-side to form a fuel assembly

•A number of fuel assemblies are, in turn, grouped to form the reactor core

Defense-in-Depth

•Multiple containment mechanisms of the fission products leading to containment within containment within containment … are referred to as defense in depth▫The first level of containment is the fuel

cladding 99% of the fission products are contained

within the cladding▫The reactor vessel containing the core and

coolant system is made of steel up to 10 inches (25 cm) thick and serves as a second layer of containment

Defense-in-Depth•The third layer of containment is the

containment building itself – the building that houses the core, coolant systems, and the reactor vessel▫The containment building is typically a

reinforced concrete structure 6 feet (1.8 m) thick

▫This makes the explosions witnessed at Fukushima Daiichi all the more impressive in their scale

The Plume

•Steam and gasses trapped within the containment vessels may be released to the environment

•Being a heated gas, it will travel above the ground and along the ground as a cloud referred to as the plume▫Obviously, exposure to the plume means

exposure to radioactive isotopes contained within the plume and should be avoided by the general public

The Plume•Public warning of how to avoid the plume should

be broadcast on the Emergency Alert System▫(formerly the Emergency Broadcast System,

formerly Civil Defense/Conelrad)•Avoiding exposure to the plume is the basis for

the evacuation zone▫US advising of a 50 mile zone in Japan was

primarily based on the earthquake devastation limiting information access (both to the public and responders) and lack of access to proper medical care in the devastation zone

Evacuation Zone• This will, however, make it difficult for a US

nuclear incident to advise less than a 50 mile radius evacuation zone▫A smaller evacuation zone makes evacuation

easier▫A larger zone impedes the ability of people to

escape, leaving people exposed and sitting in their cars on the freeway

▫Despite facts on the ground, this advisory opinion to Japan may make future US nuclear accidents more difficult to manage

Levels of Alert, Nuclear Power Plant

•There are 4 levels of alert at a nuclear power plant▫Unusual Event

Very common; does not pose a risk to the general public

200 unusual events per year in the US▫Alert

An event that should be monitored closely but does not currently present a risk to the general public

10 alerts per year in the US

Levels of Alert, Nuclear Power Plant

•There are 4 levels of alert at a nuclear power plant▫Site Area Emergency

Major failures; immediate action by the public is not necessary but the public should be informed to “please stand by” for further updates

▫General Emergency Severe incidents that call for immediate action by

the public A major release of radioactivity may not

necessarily be in progress, though it is likely imminent

Evacuation Zone

•Current evacuation/shelter guidelines suggest▫Evacuate the entire area within 2-3 miles of

the plant in all directions and people living up to 10 miles downwind

▫Shelter in place for the rest of the population living within a 10 mile radius A fallout shelter or a home with the HVAC

system turned off (to prevent air intake) can serve this purpose

Exposure and Ingestion

•As the plume deposits its radioisotope load on the ground grazing livestock will consume the isotope▫Radioactive isotopes of iodine are common

in a nuclear plant release▫This is incorporated into milk▫Contaminated milk is the most frequent

means by which radioiodine is ingested▫Those living within a range of the plant

may be advised to take stable iodine tablets

The Nuclear Threat

The Nuclear Threat• Atomic weapons are generally lower yield

weapons (in the kiloton range) and are relatively simple to produce▫A critical mass of uranium-235 will spontaneously

fission in a self sustaining chain reaction▫So that it doesn’t blow apart and fizzle out, two

halves are usually driven toward each other

▫A critical density of plutonium-239 will sustain a chain reaction as well

▫Explosive “lenses” compress the device into a critical density

The Nuclear Threat• The mathematics and practical engineering involved

in a plutonium device make it an unlikely device for a terrorist attack

• The simplicity of obtaining a critical amount of enriched uranium makes this device more “likely”

• Obtaining enriched material is exceedingly difficult because▫1) it is exceedingly expensive, so states alone usually

produce it and guard their supply carefully▫2) states that want their own weapons aren’t likely to

just give away the material

The Nuclear Threat•Thermonuclear weapons are even less

likely to be used in a terrorist event▫1000x more powerful than atomic weapons

(in the megaton range)▫Basic idea: a fission device (the initiator) is

used to generate high temperatures; high temperatures lead to fusion reactions

Atomic weapons are fission based; Thermonuclear weapons are primarily fusion based with a fission trigger

The Nuclear Threat

•Present-day weapons use solid lithium deuteride fuel (isotopes Li-6 and H-2)

•Neutrons released from the initiator convert Li-6 into tritium

Li-6 + n H-3 + He-4•The tritium (H-3) is highly energetic,

enough so that it can overcome the Coulomb repulsion of the nuclei and fuse with the deuterium (H-2) in the original fuel

The Nuclear Threat•Fusion devices have a “clean explosion”

because, while fission devices tend to be radioactive, fusion devices don’t

•However, fusion devices are hot enough so that U-238 is now fissile

The Nuclear Threat

•The device can be jacketed with naturally occurring, non-enriched uranium (mostly U-238) and increase the yield

•This increases the radioactivity of the fallout greatly

•Most thermonuclear devices have U-238 jackets that give them a “dirty” explosion because the point of a nuclear weapon is its destructive power

Response• In a nuclear detonation, our primary concerns are

▫Acoustic blast wave – the force that levels structures

▫Thermal blast wave – the heat that melts structures▫Flash blindness – a prompt release of EM radiation

in the visible spectrum that can lead to transient or permanent blindness

▫Electromagnetic Pulse (EMP) – high altitude devices can generate an electromagnetic wave that disables electronic systems, hampering response efforts (not likely in a terrorist event, possible from a rogue state attack)

▫Fallout

Blast Effects

•The human body can withstand overpressures of up to 30 psi

•Winds in a region with 2 – 3 psi overpressure, however, are usually sufficient to knock someone off their feet

0.25 miles from a 10 kT blast we find around 5 psi overpressure with winds of up to 160 miles per hour

The Mushroom Cloud•The mushroom

cloud is a rising heat plume that cools and spreads as it goes up

Fallout

•Material (dirt, buildings, etc.) is irradiated with an intense bombardment of neutrons from the device

•This material is now radioactive – its original isotopes have been transmuted into radioisotopes

•This material is carried up in the mushroom cloud and spread over a region▫As it cools, it rains down as fallout, leading

to an absorbed dose to those below

Safe Levels

•One rule of thumb is the 7:10 rule▫For every 7 fold increase in time, there is a

10 fold decrease in exposure rate▫The times must be expressed in the same

units (7 days later the rate drops from 100 R/day to 10 R/day)

Blast Effects of a 10 kT deviceEffect Range (miles) Range (kilometers)

Blast and thermal crater (everything is vaporized)

0.25 0.4

Destruction of brick structures

0.9 1.4

Destruction of wooden structures

1.5 2.4

Forest fires in dry conditions

3 – 6 5 – 10

Immediate death from initial radiation (ARS leads to death)

0.5 0.8

Fallout sufficient to kill persons in the open

10 16

Source: FEMA Emergency Management Institute Radiological Emergency Management

Triage and Response

•As we have said, triage is pointless for large scale nuclear war

•For a single small device it remains difficult and medical resources are likely to be strained greatly

Review Questions1. Distinguish between Type A packaging and

Type B packaging on the basis of surface radioactivity.

2. Distinguish between Radioactive White I, Radioactive Yellow II, and Radioactive Yellow III on the basis of surface radioactivity.

3. An airplane is flown into the cooling tower of a nuclear plant. Is radioactive material immediately released?

Review Questions

4. What is meant by “defense in depth”?

5. What are the 4 levels of alert at a nuclear facility and what do they mean?

6. What are the guidelines for evacuation and shelter-in-place in a General Emergency at a nuclear power plant?

Review Questions

7. Consider doing an analysis of a weapon for an intelligence agency. You are told it has been determined that there is a core of mostly U-235, with a significant amount of U-238 jacketing the central core. Is this an “atomic” nuclear weapon, or a thermonuclear weapon? What is the likely nominal yield (in kilotons)?

Review Questions

8. A survey of a nuclear detonation site reveals a dose rate of 100 Gray/day. What do you expect the dose rate to be 1 week later?

9. Describe the effects of detonation of a 10 kT nuclear device detonated just outside of a major metropolitan area.