Analysis of Radiation Dose Effects and
Emergency Response from Nuclear Power
Accidents
Richard Wilson
Mallinckrodt Professor of Physics (Emeritus)
Harvard University
Thursday, May 17th 2012
American Nuclear Society,
Northeastern Section
Responses to Fukushima:
NRC correctly has two papers on making reactors
safer, ANS is stressing these
BUT
nuclear power is dead for 50 years
UNLESS
ANS explains to the public that radiation is not the
disaster they think
(I continually challenge APS also)
DO NOT BE LAZY
understand and speak out
Topical issue – Fukushima a year agoEvacuate or not?
What do we know from previous incidents?
Those who do not understand history are condemned to repeat it
Medical X rays
Radium Dial painters
Hiroshima-Nagasaki
Windscale (UK)
TMI
Chernobyl
Tokai (Japan)
Avoid Acute Radiation Sickness (ARS)
ARS can occur if dose in a week is > 200 Rems (2 Sv).
But chronic doses can accumulate over years
Chronic effects:
cancer
heart disease
genetic effects
No cancers specific to radiation
Radiation can cause an increase
in natural cancer rate
Perhaps 30% at 200 Rems (maybe much less)
Suggested immediate actions
• Prior experience suggests:
• Avoid effects of iodine (don’t drink local milk (even
mother’s milk) for a month
• Evacuate if needed to Avoid Acute Radiation
Sickness
• If no Acute Radiation Sickness a day or two delay in
considering evacuation makes little difference
• Let workers get higher doses than normal subject to
acute radiation sickness
My Estimate of Dose at Site Boundary
My Dose at Site Boundary
March 2012 calculation
– Peak probably noble gases (little effect) followed by
cesium. (134 and 137)
– Take peak and multiply by width
– Dose about 2 Rems (0.02 Sv) and falling
– My CAT scan doses last year 2.4 Rems
Evaporation
Temperature
184°C
671°
C
990°C
1750°C
Products of Fission
Gases
(1) Noble Gases (Kryton,xenon)
(2) Iodine goes to thyroid: leukemia, thyroid cancers
(Do not drink milk for a month)
Solids
sublimate as temperature goes up
(A) Cesium 134, 137. do not stay
(B) Strontium, transuranics
Only at higher temperature, not much even at
Chernobyl
Table not broken down by age (MY MISTAKE!)
What about Ibaraki?
(on way to Tokyo)
It looks different with different scale.
Dose Negligible
Adverse Effects of Evacuation
– Stress can increase cancer rates 5% or more
– Direct loss of life due to lack of facilities
– NO ONE CONSIDERED THESE AT ALL
Subsequent study (IAEA, INPO, TEPCO, etc)
confirms:
•No one got Acute Radiation Exposure
•(highest exposure in a worker 30 Rems)
•If there are cancers the probability of causation
(POC) will be less than 50% in all but a few cases.
These are the locations of measurement
BEIR report on effects of radiation
Not broken down by age
These numbers are for high dose RATES
Animal studies in 1960s suggested a
reduction by 10 if low dose RATES
A rcent MIT study suggests the same.
EMPHASIZE rare human data
deposition at TECHA River
Studies after Chernobyl
Perhaps a factor of 3
Deposition to NW of plant highest from
Tuesday/Wednesday releases
Rems/man or manRems?
• Traditionally health physicists assume a linear dose
response and then it is clear that the societal effect
is best expressed in Man Rems or Person Sievert
• But here one needs the effect on an individual or the
small group being affected then Rems per man is the
proper description
(emphasized by the late Rosalyn Yalow,
Nobel Laureate who died last week)
Comparison with other disasters
Chairman Gregory Jaczko
testimony in US Congress
March 17th 2011
Recently, the NRC made a recommendation that:
“Based on the available information that we have, that
for a comparable situation in the United States, we would
recommend an evacuation to a much larger radius than
has currently been provided in Japan. As a result of this
recommendation, the ambassador in Japan has issued a
statement to American citizens that we believe it is
appropriate to evacuate to a larger distance up to
approximately 50 miles.”
What should a decision maker have done
(my personal opinion)?
• Order an immediate evacuation for many km ?
• Make it easy for any VOLUNTARY evacuation
– to avoid panic as happened after Katrina
NO
YES
• Do simple steps to reduce exposure to fall out
– including measurement
YES
• ORDER all out clean up for years
NO
• Facilitate individual towns and people in voluntary steps
• Richard Wilson paper in DOSE_RESPONSE (2012):
“Evacuation Criteria After a Nuclear Accident:
A Personal Perspective”
YES
Threshold or linearity?
It is important that you understand the argument
BUT when dose is low it should not matter
But do not in public argue with your supporters
who reject the threshold arguments
Alternate Dose-Response Models
Cancer Over Background
Excess Dose
Low dose linearity
is a general argument
• Probability of dying in a car accident in Harvard
Square is roughly proportional to the number of
cars!
• If the medical outcomes is not distinguishable
• From one occurring naturally then the argument
applies
• Most cancers
• Inherent in the multistage theory of cancer
• Lung effects caused by air pollution
British Journal of Cancer
Vol. VIII, March 1954, No. 1
Sir Richard Doll & Peter Armitage
(repeated 50 years later)
Cancer caused by a series of steps:
Does it matter if Nuclear Power is dead?
Problem is importance for terrorism:
(1) Take 1000 Ci medical source
(2) Add a few pounds TNT
(3) Explode in Wall Street
EFFECT:
(A) Less than 10 people die (situation in Brazil)
(B) 20 square miles out of action
THIS MAKES ACTION ATTRACTIVE
FOR A TERRORIST
Even more important
• What do you do if someone explodes a
nuclear bomb in Boston Harbor?
NO
• Run away as fast as you can?
• Take shelter for 24 hours till radioactivity does
and listen to which way the wind is blowing?
YES
• Then if you are in the plume run fast,
NO
but which way? Away from explosion?
• Sideways away from plume?
YES
Thank you for listening