Japanese A-Bomb DosimetryProject: Personal Recollections

Presented to the Lyncean GroupMay 14, 2008

ByDean Kaul and Steve Egbert

Hiroshima• Gun Assembly

Device• August 6, 1945• 140,000 Deaths

Estimated

Nagasaki• Implosion Device• August 9, 1945• 80,000 Deaths

Estimated

ABCC History

• 1947: President Truman authorizes NAS to create and manage ABCC– “…undertake a long range, continuing study of the biological and medical effects

of the atomic bomb on man.”• Jim Neel, Jack Schull and others conduct genetic effects studies

– Results Appear in 1956: No apparent genetic effects of radiation exposure• 1955: Francis Committee (Thomas Francis, Felix Moore, Seymour

Jablon)– NAS-organized committee to assess what should be done about ABCC research– Recommendations

• Reorganized program should continue• Unified study plan

– Focus on fixed cohorts of survivors and their children with internal comparison groups– Mortality follow-up– Highlighted need for dose estimates

• 1953-1963: Detailed shielding histories for most survivors– Within 2 km in Nagasaki– Within 1.6km in Hiroshima (42% between 1.6km and 2km)

ABCC/RERF Hiroshima SiteHijiyama Mountain

1950

Today

A Controversial Site!

Life Span Study CohortProximal(Detailed Shielding Histories)

Distal Total

Hiroshima 12,130 39,260 51,390

Nagasaki 4,077 20,524 24,601

Total 16,207 59,784 75,991

Proximal survivors are within ground ranges of

1600m at Hiroshima or 2000m at Nagasaki

Approximately 40% Are Still Alive

ABCC/RERF Follow-up Programs

• Mortality– Based on mandatory nation-wide family registration– Updated on a three-year cycle

• Cancer incidence– Hiroshima & Nagasaki tumor registries (1958 – present)– ABCC pathology program 1958 – 1972– Hiroshima & Nagasaki tissue registries 1973 - present

• Leukemia and related disorders– Leukemia registry 1950 – 1987– Hiroshima & Nagasaki Tumor Registries 1958 – present

• Clinical Examinations– Biennial exams– 70-80% participation through 25 AHS exam cycles– Adapted for use in F1 clinical study (FOCS)

• Mail Surveys– 1965 (Ni-hon-san study men), 1968 (women), 1978, 1991, 200?

Dose Estimation Efforts - Nagasaki1957 (T57) to 1965 (T65)

• T57 – York, USAF

• T65 – Auxier, ORNL

• Empirical Estimates

• Nagasaki Best Candidate for Approach– Similar Bombs

Tested

Dose Estimation Efforts - Hiroshima1957 (T57) to 1965 (T65)

• T57 – York, USAF

• T65 – Auxier, ORNL

• Empirical Estimates

• Hiroshima Poor Candidate for Approach– Similar Bomb

Not Tested

Shielding Experiments: Hardtack (1958), BREN (1962) Bare Reactor Exp., Nevada

• 0.6 Scale of Hiroshima • Bare U-235 Reactor, Co-60• Simulated Japanese

Structure Arrays– Asbestos-Cement Board

465m

343m

686m – 1097m

Structure Shielding• T65: John Auxier – ORNL• Empirical Approach: Hardtack Atmospheric Test and BREN Experiment Data• 9-Parameter Approach (majority of survivors with shielding histories)

– Shielded Dose/Air Dose =A1e-G1+A2G2+A3G3+A4G4+A5G5+A6e-G6+A7e-G7+A8G8 +A9

– Constants, Ai, have been determined by multiple linear regression analysis– Claimed accurate to within ±6% at the 50% confidence level.

• Geometry factors, G, are physical dimensions taken from the shielding "history" of interest

– SP, Penetration distance of the direct radiation through the house

– IFW, Number of interior walls shielding the survivor from the front

– ILW, Number of interior walls shielding the survivor from the side

– LS, Lateral shielding exterior to the house of the survivor

– FS, FSS, Frontal shielding exterior to the house of the survivor

– HF, Height above the air-ground interface

– US, Distance from an open window in the direction of the hypocenter

– FN, Floor number on which survivor is located

Example Shielding History

T65 - The Last Word in Empirical Analysis

‘65-‘76:Advancement of Radiation Transport Calculation Technology

• Large Scale 1 and 2-Dimensional (ANISN, DOT) Neutron and Gamma Ray Atmospheric Transport Calculations– ORNL 4464 Neutron and Secondary Gamma-Ray Transport in

Infinite Homogeneous Air. (Ed Straker, Mike Gritzner)– ORNL 4289 Time-Dependent Neutron and Secondary Gamma-Ray

Transport in an Air-Over-Ground Geometry (Ed Straker, Mike Gritzner)

• Improved Neutron and Gamma Ray Cross Sections– Differential and Integral Measurements

• Using Linear Accelerator Broad Spectrum Source with Time-of-Flight (GA, ORNL)

• Especially n-γ production– Evaluations

• Especially Nitrogen, Oxygen, Iron• ENDF/B-4 (1974)

• Adjoint Monte Carlo Shielding Calculation Technology– MISC: SAIC– VCS/MASH: MAGI/ORNL/SAIC

How SAIC Became Involved:1. 1976-A Controversial Report

• Marrow Dose Calculation Project for DNA– Adjoint Monte Carlo– Application Example

Used LANL (Preeg) Hiroshima Leakage

• ORNL Demands DNA Withdraw Report– Different than T65– DNA Refuses

• ORNL (John Auxier) Defends Its Turf– Attacks Author’s

Credentials– Defends T65 at DOE

How SAIC Became Involved:2. 1978-Nuclear Test Dose

• NTPR-Nuclear Test Personnel Review– Dose Reconstruction

for 100’s of Military Personnel Exposed in Nevada and the Pacific

• Application and Verification of Computational Methods– 1 and 2D Discrete

Ordinates Methods– 3D Adjoint Monte

Carlo Methods (MISC)

• Gives Credibility to Arguments for A-Bomb Survivor Dose Discrepancy

And Then…• 1978 – Rossi and Mays, "Leukemia risk from neutrons," Health Physics

– Neutron RBE = 100; Derived from T65 City Differences in Neutron Dose– Culmination of Numerous Reports Citing A-Bomb Survivors as Basis for More

Stringent Radiation Exposure Regulatory Limitations• 1979 - BEIR III Issued; Immediately Withdrawn due to controversy• 1980 – Bill Loewe & Edgar Mendelsohn, "Revised Estimates of Dose at

Hiroshima and Nagasaki, and Possible Consequences for Radiation Induced Leukemia (Preliminary)", Report D-80-14. (LNL)

– Consistent with Kaul (1977)• 1979 - George Kerr (ORNL) Sponsored by DOE to Assess Possible A-

Bomb Dosimetry Problems– Agrees there is a Problem, Earning the Enmity of John Auxier

• 1980 - Dean Kaul Meets with NAS Seymour Jablon– Jablon Believes there is a Problem with T65

• 1980 - BEIR III Reissued – With Larger Safety Margins• 1981 - DOE Symposium on Neutron Dosimetry

– All Parties Air Their Opinions, including John Auxier• 1983 - DOE Launch a Multi-Million Dollar Program

– John Auxier Chooses Not To Participate

A-Bomb Dosimetry Reassessment Project

• Organizations– SAIC

• Delayed Radiation Free Field• Shielding• Organ Dosimetry• Dosimetry System• Uncertainty

– LANL• Yield• Leakage

– ORNL• Prompt Radiation Free Field• Factory Shielding

– Measurements– LNL

• University of Utah• Oxford University• University of Hiroshima• Nara University• Tokyo University• JNIRS• University of Munich

– RERF• Sample Gathering• Mapping• Hypocenter Location

• SAIC Staff– Gil Binninger– Hud Dolatshahi– Steve Egbert– Mike Gritzner– Dick Hillendahl– Dean Kaul– Tom Kuhn– Mark Otis– Jim Roberts– Bill Scott– Vic Verbinski– Bill Woolson

The Parents of DS86 Hiroshima 1983

Some US Principals in this Photo: Al Lazen, W. Lowder, Robert Christy, Ed Land, Dean Kaul, Dale Preston, Bill Ellett, Seymor JablonBill Woolson, Bill Roesch, Joe PaceGeorge Kerr, Warren Sinclair, Charlie EisenhauerPaul Whalen, Ed Haskell, Fred Seitz

LANL Calculates The Weapons

• Hiroshima (Little Boy)• Yield

– T65: 12.5 kT– DS86: 15 kT

• HOB– T65: 577 m– DS86: 580 m

• Nagasaki (Fat Man)• Yield

– T65: 22 kT– DS86: 21 kT

• HOB– T65: 503 m– DS86: 503 m

Hydro & Leakage Calculations

• Two-Dimensional– Hydrodynamics

• Includes Air Around Weapon

– Leakage• Neutrons• Gamma Rays

140µs

757µs

Neutron Leakage• Hiroshima

– Iron Moderated Spectrum

– Fast Neutrons Between 100keV and 1MeV

– Small Epithermal Component

• Nagasaki– Hydrogen Moderated

and Filtered Spectrum– Fast Neutrons

Between 1MeV and 5MeV

– Very Large Epithermal Component

Hiroshima

Gamma Ray Leakage

• Hiroshima– Fission Gamma

Rays– Iron Inelastic nγ– Iron Shielding

• Nagasaki– Capture Gamma

Rays• Nitrogen• Oxygen• Hydrogen

– Negligible Shielding

Hiroshima

LANL: Replica Project• 2-D Calculations

– Leakage• Included Air & Ground• To ~400m Horizontal

• Replica Project– Hiroshima Weapon

Case– Matching Fissile

Components– Foil Measurements to

Validate Cross Sections (SAIC: Verbinski)

– Approach to Critical to Validate Most Likely Yields

ORNL & SAIC: DS86 Free Field

SAIC: DS86 Shielding• 21 Locations• 16 Directions• 4 Distances• 1344 Unique

Shielding Parameter Combinations

• Rank Partial Correlation Shows– 5 Parameters Effective

• FS• FSS• US• FN• SP

SAIC: DS86 Organ Dosimetry• Basis:ICRP 23; M.

Christy (ORNL); Japan Statistics

• Three Anthropomorphic Phantoms– Infant– Child– Adult

• 3 Postures• 15 Organs• Energy/Angle

Differential Adjoint Leakage from Energy-Differential Average Organ Fluence

DS86 System

RERF Data Base for Individual Survivors

City,Distance

FromGround Zero

Location in House or

Street

Size, Sex, Orientation

Posture

Medical History

Unshielded Radiation

environment

House Shielding

Body Shielding

Doses and Uncertaintie

s

Radiation Risk

Estimates

DS86

SAIC Invents a New Dosimetry System for DS86

• Multi-Component System– Air Transport from

Weapon Leakage– Shield Propagation– Organ Dosimetry

• Doubly-Differential Adjoint Particle Coupling– Energy-Angle

Differential Intermediate Results

– Dose and Scalar Spectra in Organs

• Uncorrelated Components; Unlike T65

Contrasting T65D & DS86 Systems

S"

S'

DS86: Integration of Independent Calculated Components

S E freefield

shield shield

S E shield

man man

E

man

S E S E S E n S dS dE d S E

S E S E E n S dS dE d E

K E E dE Dose

", ", "

*

', ', '

*

" , " , " " , " , " , ' , ' , ' " " " " " ' , ' , '

' , ' , ' ' , ' , ' , ' ' ' ' '

T65D: Multiplication of Interdependent Empirical Components

Dose Dose Shielding Factor Organ Dose Factorman freefield Parameter Globe Factory * *, ,9

DS86 VerificationSulfur Activation

• U of Tokyo– Suspects A-Bomb– Collects Sulfur from

Telephone Poles– Measures S Activation

• Fast Neutron Activation (at Hiroshima)

• Sensitive to Weapon Tilt

• 3D Calculation Required to Match Data

• Large Uncertainty Bands at Large Distances

Sulfur Measurements

0

1

2

0 200 400 600 800 1000 1200 1400

Ground Range

M/C

Sulfur Activaion

0

500

1000

1500

2000

2500

3000

3500

0 200 400 600 800 1000 1200 1400

Ground Range (m)

P-3

2 D

PM

/gr

S A

TB

Measured

DS86

DS86 VerificationCobalt Activation

• Thermal Neutron Activation (at Hiroshima)

• Samples Embedded in Complex Geometry Objects

• Poor Agreement with Calculations

DS86 VerificationEuropium Neutron Activation

• Thermal Activation• Hiroshima

– Calculations High Below Bomb

– Calculations Diverge from Measurements Beyond ~900m Slant Range

– Similar to Co Results

• Nagasaki– Large Spread in

Measurements– Nominal Agreement

with Calculations– Calculations High

Under Bomb

DS86 Accepted Because TLD Measurements Support Calculations Over T65

In Spite of Neutron Problems,No Going Back to T65!

DS86 Status at Release• Gamma Dose, Shielding, Organ Dosimetry Improved

Significantly Over T65D

• The Neutron Discrepancy is the Most Severe of All Outstanding Dose Problems

– Affects all Hiroshima survivors– Cast doubt on the entire dosimetry system

• The Neutron Discrepancy is not the Only Remaining Problem, Others:

– Shielding uncertainty/discrepancy– No dose values for approximately 15% of survivors

• Impact of Problems if Left Unresolved:– High neutron dose uncertainty for most influential data base– Highest uncertainty for Hiroshima portion (2/3 of total data base)– Probable over-estimate of gamma-ray health risk– Inability to establish dose risk relationship at low doses (dose < 100 rads)– No usable data base for neutron, heavy charged particle risk assessment

Celebrating DS86 Completion

• DS86 Approval Announced in Hiroshima

• Japanese Hosts Suggest a Banzai Cheer in Celebration

• Older US Participants Refuse to Participate

And Then…DS86 from 1987 to 1999

• 1987 - DS86 Released• 1990 - BEIR V Released• Unanswered Questions in the 90’s

– Uncertainty Discrepancy• Predicted Uncertainty ~35%• Observed Uncertainty (from bio-dosimetry) ~45% or Greater

– Unresolved Neutron Activation Discrepancy Suggests Neutron Dose Bias at Hiroshima

• Europium• Cobalt

– Japan Courts Denounce DS86 for use in determining survivor compensation

Post-DS86

• Japan Measurements Challenge US Calculations

• DoE Funding Dries Up

• DSWA/DTRA Slips SAIC a Few Bucks to Keep Up Interest

The Problem Worsens

• More Neutron Measurements– Eu-152– Co-60– Cl-36 (AMS)– Ni-63 (AMS)

• Seem Consistent• But Require a

300m Relaxation Length– Calculated

Relaxation Length = 140m

1993: Partial Progress

• ENDF/B-6.2– Air Cross Sections– Iron Cross Sections

• Switch from 46 to 178 Neutron Cross Section Energy Bands

• Nagasaki– Discrepancy under

bomb resolved

• Hiroshima– No improvement

ENDF/B 6.2178 Energy Bands

DS86

1993 Difference AnalysisRequested by DSWA/DTRA

Could More Fast Neutrons Have Leaked From the Hiroshima Weapon?

Popular Japanese Theory:If the case had cracked,neutrons with a near-fissionspectrum might have leakedfrom the waist

+/-30 deg Horizontal Pancake

+/-30 deg Vertical Cone

1E-5

1E-4

1E-3

1E-2

1E-1

1E+0

1E-6 1E-5 1E-4 1E-3 1E-2 1E-1 1E+0 1E+1

Neutron Energy(MeV)

mole

/kt0

/leth

ds86 (ds93)

Calculation

Wild Theories Abound• Japan Suggests

the Bomb Cracked Before Neutrons Were Emitted

• US Tries– Directional

Fission Spectrum Leakage

• Pancake• Funnel-cake

– Spectrum Optimization

• Emissions from a Moving UFO are Seriously Considered 2.3MeV

Finally, Action!

• BEIR 7 is Needed to Support Radiation Regulatory Updates

• BEIR 7 is Put On Hold Because of Unresolved Problems with DS86

• DoE is Moved to Action, Again

Get It Right This Time!

• 2000 – DoE Resumes Dosimetry Program Funding

• 2000 - Hiroshima: Challenged to Solve Problems in One Year

• 2001 – Hiroshima: Japanese Find More Measurements that Disagree with Calculations

• 2001 – Cleveland: German Measurement Agrees with Calculation, No Resolution, Angry Japanese

2001 The Case Against 152 Eu Disagreement

• More Measurements Available at Hiroshima and Nagasaki

• Discrepancy– Exists at Both

Cities– Commencing at

Same Level: ~3.5 Bq/mg

– Inconsistent with NTS Test Comparisons

BUSTER-J ANGLE DOG ACTIVATION CALCULATION AND MEASUREMENT COMPARISON .

1E+13

1E+14

1E+15

1E+16

1E+17

1E+18

1E+19

300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000 2100 2200 2300 2400

SLANT RANGE (M)

FLU

EN

CE *

SLA

NT R

AN

GE

2 (N/c

m2 *m

2 )

S32 irdf90

shielded Au(total)

shielded Au(prompt)

shielded Au(delay)

S32n,p (Meas) .299 barn

Au Diff (Meas) 98 barnS32

Au

0.00

0.25

0.50

0.75

1.00

1.25

1.50

1.75

2.00

300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000 2100 2200 2300 2400

SLANT RANGE(M)

MEA

S/C

ALC R

ATIO

S32 irdf90

shielded Au(total)

Au M/C Fit

S M/C Fit

Confirmation of Technology

• Nagasaki-Like NTS Test

• Calculations Agree with Measurements– Fast (Sulfur)– Thermal (Gold)

• Calc. Using ENDF/B-6.2 Cross Sections

Final Path to Success!

• 2002 – Hiroshima: Europium and Chlorine Discrepancies Resolved by Japanese, Embarrassed Japanese– New Komura Eu Activation, Nagashima Cl at Hiroshima– Dr. Kosako (U of Tokyo): “What will we tell them?”– Japanese Regain Composure, Challenge Calculators to Explain

Short Range Thermal Neutron Activation Discrepancy• 2003 – Pasadena: HOB Increase Accepted as Answer

to Japanese Challenge– Hiroshima Burst Height Raised from 580m to 600m, based on

Thermal Activation Measurements– Tops of 6 story building near ground zero at Hiroshima, but not

Nagasaki– Hiroshima Yield Changed to 16kT– Hiroshima Hypocenter Changed, Based on New GIS Analysis

Thermal Neutron Discrepancy Resolved

Hiroshima FIA 152Eu & 36Cl (as 152Eu)

0.001

0.01

0.1

1

10

100

1000

0 200 400 600 800 1000 1200 1400 1600Ground Range, m

Act

ivat

ion

Bq

/mg

P reIntercomparison EuDistant EuEu (Int)All Cl (as Eu)DS02DS86

Hiroshima FIA 152Eu & 36Cl (as 152Eu)

10

100

1000

0 100 200 300 400 500Ground Range, m

Act

ivat

ion

Bq

/mg

P reIntercomparison EuDistant EuEu (Int)All Cl (as Eu)DS02DS86

Nagasaki FIA 152Eu

0.001

0.01

0.1

1

10

100

1000

0 200 400 600 800 1000 1200 1400 1600Ground Range, m

Act

ivat

ion

Bq

/mg

Measurement

DS02

DS86

Nagasaki FIA 152Eu

10

100

1000

0 100 200 300 400 500Ground Range, m

Act

ivat

ion

Bq

/mg

Measurement

DS02

DS86

Nagasaki TLD Gamma Dose

-1

0

1

2

3

4

500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000 2100 2200Slant Range(m)

M/C

Measurement

Fit

DS02 Gamma Ray Dose Verified Using TLD Meas.

Hiroshima TLD Gamma Dose

-1

0

1

2

3

4

500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000 2100 2200

Slant Range(m)

M/C

MeasurementFit

Hiroshima FIA TLD Gamma Dose

0.01

0.1

1

10

100

1000

500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000 2100 2200Slant Range, m

Do

se, G

y

Measurement

DS02

Hiroshima FIA TLD Gamma Dose

0.01

0.1

1

10

100

1000

500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000 2100 2200Slant Range, m

Do

se, G

y

Measurement

DS02

With Shielding+10%

+10%

Agreement within Uncertainty

Validity of the Assigned Total Uncertainty – The Test

• 41 Survivors• Chromosome Aberration (Cs) Total Dose• Tooth Dose (Lingual) Gamma Dose• DS86 to DS02; DS02 to Custom Location/Shielding (SHLD02)

Validity of the Assigned Total Uncertainty – The Finding

• DS86: Variability Much Larger than DS86/DS02 Uncertainty Assessment

• DS02: Variability Consistent with DS86/DS02 Uncertainty Assessment (±25% to 40%)

• SHLD02: Variability Much Improved

At Last…(DS02)

• 2003 – Hiroshima: DS02 Declared Finished; All Discrepancies Satisfied

• 2004 - DS02 System is Assembled in Hiroshima and Documented

• 2005 - DS02 Report Published

RERF Epidemiology:An Unfinished Story

• Life Span Study– 339 Excess

Cancer Deaths (circa 1990)

– 1 Sv (Sievert) = 100 REM

• Acute 0.2 Sv Risk– Absolute– Relative

• Results Will Continue to Accrue Until ~2028

Table 1. Cancer deaths between 1950 and 1990 among Life Span Study survivors with significant exposures

Dose rangeNumber of cancer

deathsEstimated excess

deathsAttributable fraction

0.005 - 0.2 Sv 3391 63 2% = 100×63/3391

0.2 - 0.5 Sv 646 76 12%

0.5 - 1 Sv 342 79 23%

1 Sv - 308 121 39%

ALL 4687 339 7%

Table 2. Lifetime cancer risks for atomic bomb survivors who received an acute dose of 0.2 Sv.

Age at exposure(yea

rs)Excess lifetime risk

Background lifetime risk

Excess relative risk

Men 10 0.03 (3%) 0.26 12% = 100×0.03/0.26

30 0.02 (2%) 0.28 7%

50 0.01 (1%) 0.18 6%

Women 10 0.05 (5%) 0.19 26%

30 0.03 (3%) 0.20 15%

50 0.01 (1%) 0.15 7%

Room for Improvement?• Gamma Ray Dose Inconsistencies• Survivor Location Improvement

– Use GIS Technology– Create a Geo-Referenced Collage of Pre-Attack

Photos• Custom Shielding Calculation

– Survivor Location According Shielding History– Houses Located According to GIS Collage

• Reduce Uncertainty by Between a Third to a Half

• Improved Biodosimetry– Chromosome Aberations– Electron Spin Resonance

• There Are No Plans for These at This Time

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1262.0

1261.5

1261.0

1260.5

1260.0

1259.5

1259.0

1258.5

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