Transcript ANS_May17_2012 - Harvard University Department of Physics

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
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
Effects of Low Doses
Probability of Causation
and implications for
Public Policy
The Future of Nuclear Power may
depend upon a Rational Approach to
Risks of Radiation Exposure
and their regulation.
What are they?
Do we compensate those exposed?
If not what?
LINEARITY
AT LOW DOSES
IS USUAL!!
Walking blindfold across
Harvard Square is safe:
(Risk (R) = 0)
IF THERE ARE NO CARS!
The risk (R) increases roughly in proportion
to the number of cars.
Acute Effects
Characteristics
• One dose or dose accumulated in a short time KILLS
• 1/10 the dose repeated 10 times DOES NOT KILL
CHRONIC EFFECTS including CANCER
Characteristics
A dose just sub-acute
can give effects if repeated.
Usually not all people affected dose response is flatter
Typically an accumulated
Chronic Dose = Acute LD50
gives CANCER to 10% of the population.
E.g. LD50 for radiation is about 350 Rems.
At 350 Rems about 10% of exposed get cancer.
(more or less depending on rate of exposure)
Early Optimism Based on Poisons
There is a threshold below which nothing
happens
__________
J.G. Crowther 1924
Probability of Ionizing a Cell
Linear with Dose
Repair Mechanisms
BUT
Does the Mechanism Reject/Repair:
ALL DAMAGED CELLS UP TO XXXX?
(implying a threshold)
OR 99.999% of CELLS
INDEPENDENT OF DOSE
WE DON’T KNOW
CRITICAL ISSUES FOR LINEARITY
• The POLLUTANT acts
in the same way as
whatever else influences the CANCER RATE
• CANCERS caused by the POLLUTANT
are INDISTINGUISHABLE from other cancers
Probability of Causation
Come let us Cast Lots to find out
who is to blame for this ordeal.
Jonah 1:7
Probability of Causation
equals
Risk from Substance
divided by
Risk from all Causes
Risk from all causes can be
approximated as the Prevalence in
a similar Population.
If the cancer is rare, POC can be
high even if the risk is low.
E.g
POC for berylliosis is unity for
beryllium as a cause
POC for asbestos exposure as a
cause of mesothelioma among
males is 80% and 20% among
females
Administrative Uses
of the POC concept:
Aluminum workers in Quebec
(compensate if POC > 50%)
Radiation Workers in UK
(compensate if POC >20%)
Compensation for Radiation Exposures
1985 - Veteran “Downwinders”
(if upper 99th percentile of POC > 50%;
effectively POC >5%)
1996 - UK Workers
(if POC >20%)
2000 - Old AEC employees
(if upper 99th percentile of POC > 50%;
effectively POC >5%)
Medical Causation
General Causation:
the Postulated Cause is Known to Cause the
Disease under some conditions
(POC>0)
Specific Causation, exposure and other
circumstances make POC large enough (>50%)
What do the Courts say?
US Supreme Court
Daubert
Joiner
Kumho Tire
General Causation needs a Risk
Ratio that is significant,
statistically and otherwise
Usually RR>2
(POC >50%)
Rule to avoid frivolous lawsuits:
The postulated cause must be
“more likely than not”
POC>50%
But
Rutherford instruction
If total asbestos exposure is a proven
cause, it can be assigned to individual
suppliers even if POC < 50%.
RISK of respiratory ailments
due to LIFETIME EXPOSURE to
AIR POLLUTION is
3 to 5% average in the USA!
POC varies from 30% to 80%
If I develop leukemia:
The POC from my Medical Exposures
would be over 50%
Can I sue using the Rutherford case?
Minister of Health, UK
US State Department
Harvard University
Commonwealth of Massachussets
ONR
DOE (AEC)
Assignment of a Cause does not
mean that Compensation is
payable.
E.g.
Chemotherapy agents are often
carcinogenic and increase risk of
future cancers even as they cure.
Go back to the beginning:
Does it make sense?
Can we study those cohorts where NIH
calculate POC near 50%?
Risk Ratio of 2?
Those x-rayed just post world
war II?