Transcript Radiological Dispersion Devices and Nuclear Weapons An Overview Victor E. Anderson, C.H.P. Radiologic Health Branch California Department of Public Health.

Radiological Dispersion Devices
and Nuclear Weapons
An Overview
Victor E. Anderson, C.H.P.
Radiologic Health Branch
California Department of Public Health
Use of Radioactive Materials for
Terrorist Attack
• Few, if any deaths due to radiation.
?
• Possible deaths due to the explosion.
Use of Radioactive Materials for
Terrorist Attack
• Most likely impact will psychological.
• The most important impact will be
economic.
Radiation Dose Delivery
• External Dose
– Source
– Fragments
– Fallout
• Internal Dose
– Primarily inhalation pathway.
Radiological Dispersion Devices
can vary in complexity and
design.
Radiography Source
Plastic Explosive
OR
Lid w/explosive bolts
Cooling system for
decay heat is required
High Level Source
MegaCuries or more
Mechanism for introducing
explosive charge and detonating
weapon
Shielding
Types of RDD
• Improvised
• Purpose Built
• Manufactured
Most Likely RDD
• Economy of force and physics
• Improvised
• Explosive
• Possibly incendiary
Potential Radionuclides.
• Primary
–
–
–
–
–
Co-60
Cs-137
Ir-192
Sr-90 (Y-90 in equilibrium)
Am-241
• Based on availability and manufactured
quantities.
Other Radionuclides
• Pu (Generally Pu-239 or Pu-238)
• U-235
• Thorium
– Heavy Metal issues - ~ 109 mCi/metric ton
• Radium
– Issues with obtaining sufficient quantities.
As the Cloud Moves Down Wind
Radioactive material is deposited as fallout.
Radiation Issues
• Ionizing Radiation
– Emission of energy
– X & Gamma Radiation
– Beta and Alpha
• Measured in rem and millirem
– Rates: rem/hr; mrem/hr
– 100 rem = 1 Sievert
Radiation Issues
• Dose = Dose Rate X Time
– 120 mrem/hr X (½ hr) = 60 mrem
• Immediate damage does not occur until
after 100 rem of dose.
• Annual radiation worker limit: 5 rem/yr
• Public dose limit: 100 mrem/yr
– Long term effects have not been detected at
these low levels.
Radioactive Contamination
• Contamination is the presence of
radioactive material in a place where it is
not wanted.
• Radiation
Contamination
• Contamination does emit radiation.
• Major concern is inside people.
First Responder Issues
• TURN ON YOUR SURVEY METERS!
• Use ICS and SEMS
• Life saving takes precedence over radiation
control issues.
• Do keep track of first responders radiation
dose.
• Remember: dose rate X time = dose.
First Responder Issues
•
•
•
•
•
Call for help.
Use SEMS to ask for:
Radiologic Health Branch Strike Teams
Ca National Guard Civil Support Team
DOE Radiological Assistance Program
(RAP) Team.
Care for Contaminated & Injured
• Contamination levels on patients
– Will not cause radiation injuries to care givers.
– Will not cause care givers to become
“casualties.”
– Are a hygiene issue.
• TAKE CARE OF MEDICAL ISSUES
FIRST!!!
Care for Contaminated & Injured
• When the patient is stabilized
– Survey – where is the contamination?
– Remove clothing as needed.
– Use gauze, sponges, small amounts of soap and
water, or “baby wipes” to clean the
contaminated areas.
– Use sheets and blankets to contain any
contamination that can not be cleaned in the
field.
Care for Contaminated & Injured
• At the ER
– Do use a special area to survey and receive the
patient.
– At the same time do the usual medical
screening.
– Take care of the patient’s medical problems.
– Decontaminate last.
– Don’t lose track of patient’s condition.
Controlling Contamination
At the ER
OUT
IN
PATIENT
Downwind Issues
• Assessment
• When to evacuate?
• Mass decontamination and screening
• Recovery
Assessment
•
•
•
•
•
Use computer models and measurements.
Project where contamination is and levels.
Determine projected dose rates
Rapid
Recommendation to Incident Command and
Emergency Operations Center
When to evacuate?
• Use EPA Protective Action Guides (PAG).
– Based on dose from deposition.
– Greater than one rem in 24 hours.
– Greater than two rem in one year.
• Use State Dose Assessment Center. If not
available use:
– Radiologic Health Branch Teams
– Radiation Assistance Team (RAP)
Mass Decontamination and
Screening
• Radioactive contamination is easily
removed – soap and water, waterless
cleaners, etc.
• Radiation dose to contaminated individuals
is small.
• Major issue is decompression of individual
and collective fears and concerns.
Mass Decontamination and
Screening
•
•
•
•
A plan is necessary.
Gives the population direction and hope.
Prevents mass exodus to hospitals.
Must plan for large numbers ~ one million
persons.
• Reception centers.
Mass Decontamination and
Screening
• Giving everyone a shower is not the
answer!
~ 10% of the population is medically
challenged.
• Not all will be contaminated.
Worried well problem.
• Some will only be partially contaminated.
Reception Centers
• Enough survey meters.
• Supplies.
– Decontamination
– Clothing
• Concentrate on minimum use of water.
• Documentation
• Volunteer Nuclear Medicine Doctors and
Radiation Oncologists
Public Communication
Clear
Multiple Languages
Provide Good Information
Public Communication
• Can help to prevent panic.
• Key to keeping uninjured from going to
hospitals.
• Must be followed up by educational
materials.
– What is radiation?
– What is the danger?
– What can I do?
Law Enforcement Issues
• Evidence Collection and support.
• Security for first responders with respect to
issues such as secondary devices.
• Security of the site to assure that
unauthorized personnel do not enter.
• Crowd control and assistance for evacuees.
• Traffic Control
Surveillance Issues
•
•
•
•
Determine contamination levels.
Plume projections help.
Need teams to survey ground.
Sample for loose and fixed contamination.
– Loose contamination is radioactive material that is
easily transferred from one surface to another.
– Fixed contamination does not move easily.
• Suitable air, water, and other environmental
testing.
Laboratory Issues
• Identification of the radioactive materials
– Will occur almost immediately.
– Field methods are sufficient.
• Laboratories will be needed to:
• Analyze large numbers of samples for
radioactive materials content.
– Air
– Water
Plants
Meats
Dairy Products
Laboratory Issues
• Does not require environmental sampling
sensitivities – e.g., picocuries or less.
• High throughput
• Shorter count times.
• Good documentation.
• Sample dose rate limits should be based on
equipment limits.
Laboratory Issues
• Laboratory personnel should be able to
easily stay within radiation dose worker
limits.
• Contamination control will be an issue.
• Storage and documentation of samples.
– Radioactive
– Non-radioactive
Some Thoughts
• How big – kilotons
• What will it do?
• How far?
• How many?
Nuclear Weapon Basics
• What is an explosion?
– A very fast fire that has no place to go.
• Chemical Explosion
– Powered by chemical changes
• Nuclear Explosion
– Powered by nuclear changes
• Fission
• Fusion
Fission Process
• Fissionable Materials – U-233, U-235, Pu239.
• Atom is split by a neutron and you get:
– Two or more smaller atoms
– Two to three neutrons.
• Other atoms may or not be split.
Criticality
• Sub Critical
– Does not sustain fission
• Critical
– Neutron Population Steady
– Cannot extract power
• Supercritical
– Neutron population growing slowly
– Can extract useful power.
Prompt Critical
• Neutrons are increasing very fast.
• Nuclear reaction is running away
• Result: A very, very fast burning nuclear
fire.
• If confined, so that the explosive forces
build up, then an explosion occurs.
Types of Fission Bombs
• Gun type
Types of Fission Bombs
• Implosion Type
High Explosive
Subcritical Core
Construction Issues
• Gun type is easiest to make.
– Less efficient
– Larger and heavier
• Implosion type is much harder
– More efficient
– Lighter and smaller
Type of Weapon Used
• Stolen
– “Suitcase” bombs ~ 0.1 to 10 kt
– Tactical Warheads ~ 1 to 20 kt.
• Improvised
– Gun type
– ~10 to 20 kt Range
National Planning Scenario
• Ten kiloton Weapon
• Major urban area
– Business Centers
– Ports
– Malls
• California CDPH Scenario
– Ground Burst
Effects Part One
• Intense nuclear reaction lasting for a tens to
hundreds of microseconds.
• Fireball formation
• Light in the form of visible light, heat, and high
energy photons (x and gamma rays).
• Neutron Radiation
• Electro-magnetic Pulse (EMP)
• Shock or concussion wave.
• Radioactive materials leading to fallout.
The Fireball
• Temperature starts at millions of degrees
centigrade and falls to about 3,000 degrees
centigrade at the maximum radius.
• Size varies with strength.
R ≈ 145 (kt)0.4 for contact surface.
R ≈ 110 (kt)0.4 for air burst.
R ≈ 90 (kt)0.4 for surface burst.
Fireball Radius for 10 kt Surface Contact Burst
10 kt Distance to Ignite Structures
(50 cal/cm2)
10 kt Approximate Distance For Third Degree Burns
(~ 8 cal/cm2)
Immediate Ionizing Radiation
Effects
• Large burst of X, Gamma, and Neutron
radiation is given off during the explosion.
• For a dose of 1,000 rad, essentially 100%
fatalities.
• For a dose of 500 rad, approximately 50%
fatalities without medical care.
• “Natural” shields such as hills, concrete
structures, etc. can provide some protection.
10 kt 1,000 Rad Immediate Dose
500 Rad Immediate Dose
Shock Wave
• The explosion will create a “wall” of
compressed air that expands outward.
• This creates the blast or concessive effects.
• Damage is highly dependent on height of
burst.
• Air or Ground
Shock Wave
• Ground Burst
• Wave moves up and along the ground.
–
–
–
–
Broken up by terrain features.
Hills
Valleys
Buildings
• Less efficient in causing damage.
Shock Wave
• Difficult to predict Destructive Effects
• Rough Guides
– Generally an over pressure of ~ 5 - 10 psi will
severely damage most structures.
– 10 kt airburst should severely damage all
structures out to about ½ mile from the
explosion’s center (ground zero).
Shock Wave Damage
• Fragments
• Secondary fires
• Explosions from gas tanks
• Damage to vehicles and aircraft.
Potential Shock Wave Damage 10 Kt
Shattered Glass Injuries
Severe Building
Damage
Fallout
• Probably the most dangerous effect from a
nuclear weapon.
• The amount depends on size and type of
burst.
• Ground burst yields the largest amount.
• Air burst yields the lowest.
• Weapon can be surrounded with Cobalt or
other materials to enhance fallout.
Fallout
• Spread and extent is highly dependent on
weather conditions.
• Individuals may be killed from radiation
exposure.
• Best defense is to leave or get into a
shielded shelter (fallout shelter).
• Arrival time depends on wind speed.
Fallout
• Composed of fission fragments, activation
products, and unused nuclear fuel.
• Initially decays off very rapidly.
A(t )  Aot
1.2
• A(t) = activity after a period of time (t)
• Ao = equal activity at start.
Fallout
• Dose rate follows previous activity decay
law.
• After about six months, then fallout decays
based on the longer lived materials.
• An initial dose rate of 1,000 rad/hr will fall
to about 2 rad/hr in a week.
10 kt Idealized Fallout Dose Rates and Times
(15 MPH Wind Blowing from the South to the North)
500 R/hr
Arrival Time ~ 35 min
1,000 R./hr
Arrival Time ~ 20 min
minutes
Fallout Issues
• Get population out of the area fast.
• Radiation burns from heavy fallout can
occur.
• Recommended that individuals in the areas
of greater than 10 rad per hour take a
shower.
• Field decontamination will be complicated
by injuries and ill population.
Response Issues
•
•
•
•
•
Major event
Initial confusion and chaos
Set up EOC and Command Posts up wind.
Define work areas
Safe area
< 2 mrem/hr
No special radiation precautions
Work Areas
• Emergency Zone
– Area where workers can maintain doses less than or equal
to 5 rem per year. (State radiation worker limits).
– Contamination control may require level A or equivalent
PPE.
– Search and Rescue will be difficult.
• Life Saving Zone
– Entry only to save lives.
– Doses must be less than 100 rem per entry.
• Lethal Zone
– No Entry
– Dose Rates are too high.
Work Zones
• Zones will shrink as fallout decays.
• Controlling rescue worker’s dose is a must.
• Survivors who have greater than 1,000 rad
are dead.
• Organization will be the key to survival.
Casualties
• CDPH Studies for a 10 kt Ground Burst Indicate
– Approximately 60,000 individuals killed outright.
– An additional 60,000 individuals at risk from radiation
syndrome death due to fallout.
• Death due to fallout radiation will be prolonged
ranging from days to weeks.
• An extreme challenge to the local, state, and
national medical care system.
Fallout Injuries
• Unknown
• Subject to factors of evacuation and time in
area.
• For a ground burst, clearly higher.
• Will require decontamination.
• Beta burns.
• Possible whole body irradiation.
Refugee Issues
• Plan for large numbers.
• Consider how to screen rapidly.
– For contamination.
– For injuries.
– For needs.
• Places to go.
• System must be humane.
Radioactive Screening
• Hand held instruments.
– Inexpensive.
– Labor intensive.
• Portal Monitors
– Expensive.
– Less labor.
– Quick.
Concluding Remarks
• The planning problem involves many
different disciplines.
• Because radiation issues will affect virtually
everything, the Health Physicist ends up as
a technical advisor, facilitator, and catalyst .
Hiroshima Today. Ground Zero is near the Center of the Picture
Concluding Remarks
• With correct planning and training a good
response can happen.
• Clear objectives, good equipment, and a
well led and organized response
organization can prevail.