Radia2on Exposure to the Popula2on in Japan After ...

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Oct 31, 2011 - Radioisotopes in dusts released by. Fukushima Daiichi units. • Radioiodine. • Cesium-‐134 and-‐137. • Cobalt-‐60. • Fission wastes and ...

Radia%on  Exposure  to  the   Popula%on  in  Japan     A6er  the  Earthquake   Marco  Kaltofen,  MS,  PE  (Civil,  MA)   Department  of  Civil  and  Environmental  Engineering   Worcester  Polytechnic  Ins%tute   Worcester,  MA   [email protected]     Presented  October  31,  2011,  at  the  139th  annual  mee%ng  of  the   American  Public  Health  Associa%on,  Washington,  DC    

  Radia%on  Exposure  to  the  Popula%on  in   Japan  A6er  the  Earthquake  

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Presenter  disclosures   The  following  personal  financial  rela%onships   with  commercial  interests  relevant  to  this   presenta%on  existed  during  the  past  12  months:      No  rela%onships  to  disclose  

Radiation Exposure to the Population in Japan After the Earthquake

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Acknowledgments   •  Fairewinds  Energy  Founda%on   •  Dept.  of  Physics,  WPI   •  Dept.  of  Civil  and  Environmental   Engineering,  WPI   •  Hanford  Challenge   •  Safecast  

Radia%on  Exposure  to  the  Popula%on  in   Japan  A6er  the  Earthquake  

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Hypothesis   •  Dust  contaminated  with  fallout  from   the  Fukushima  accidents  is  a  source  of   human  exposure  to  radia%on.  

Radia%on  Exposure  to  the  Popula%on  in   Japan  A6er  the  Earthquake  

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Radioisotopes  in  dusts  released  by   Fukushima  Daiichi  units   Radioiodine     Cesium-­‐134  and-­‐137     Cobalt-­‐60     Fission  wastes  and  neutron  ac%va%on   products   •  Uranium  and  plutonium  fuels  and   transuranics  such  as  americium  and   neptunium       •  •  •  • 

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How  are  people  exposed  to   radioac%ve  par%culates?   •  Inhala%on  of  airborne  par%cles   •  Inhala%on  of  resuspended  dusts   •  Inges%on  of  contaminated  food   (seaweed,  shellfish,  beef,  milk,  spinach,  eggs,     tea  and  finfish  including  pollock  and  cod)   •  Inges%on  of  soils  and  dusts  (pica)   •  Dermal  contact   Radia%on  Exposure  to  the  Popula%on  in   Japan  A6er  the  Earthquake  

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Common  materials  that  retain     radioac%ve  par%culate  ma`er     •  •  •  •  •  •  • 

Car  air  filters,  ~  650  M3air  /mo.,  qualita%ve   37  mm  air  filters,  30  M3air  /  d.,  quan%ta%ve   Home  air  filters     Shoes     Se`led  dusts     Surface  soils   Food  and  plants   Radia%on  Exposure  to  the  Popula%on  in   Japan  A6er  the  Earthquake  

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Air  sampling  sta%ons  

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Primary  radioisotopes  detected   •  Cesium-­‐134  and  cesium-­‐137   •  Iodine-­‐131    (short  lived)   •  Cobalt-­‐60   •  Fission  products         Detected  as  elements  by  SEM/EDS  and  as  isotopes     by  gamma  spectrometry,  with  total  α  &  β  counts.  

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Cs-­‐137  Distribu%on  –  Fukushima  Prefecture     NMEXT  and  US  DOE  Data  

Radia%on  Exposure  to  the  Popula%on  in   Japan  A6er  the  Earthquake  

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Permissible  doses  in  Fukushima   Prefecture,  2011   •  Raised  from  1  mSv  yr-­‐1  to  20  mSv  yr-­‐1        (100  mRem  yr-­‐1    to  2000  mRem  yr-­‐1  )     •  US  general  public  limits:      10  mRem  yr-­‐1    EPA  and  100  mRem  yr-­‐1    NRC  

  Radiation Exposure to the Population in Japan After the Earthquake

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Collec%ng  samples  from  Japan   •  Sampling  team  includes  university  scien%sts,   bloggers  and  farmers,  all  with  varied  technical   training   •  Requires  educa%on  on  safety  and  sample  care   •  Must  be  cognizant  of  cultural  issues   •  Requires  safe  and  legal  shipping  methods,   despite  involving  common  everyday  items,   especially  for  biologically  ac%ve  soils            

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Autoradiographs  –  car  air  filters   April  2011,  X-­‐ray  film  image  and  uR/hr.    

   Sea`le  m=11.7    

         Tokyo  m=18.9                      Fukushima  City  m=199    

Radia%on  Exposure  to  the  Popula%on  in   Japan  A6er  the  Earthquake  

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Examining  individual  radioac%ve  par%cles    

Ibaraki  dust  sample,  collected  4/4/2011,                               High  z  par%cles,  (Eu,  Y,  Zr,  Th,  Ce,  Sr,  Ce),  in  1  to  15  um  size  range   Analyzed  by  SEM/EDS  and  gamma  spectrometry     Radiation Exposure to the Population in Japan After the Earthquake

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Radia%on  on  children s  shoes   Fukushima   48.8  uR/hr.  σ  =  15.4,     USA  mean   10.6  uR/hr.  σ  =    0.68  

 

Elementary  schools  soils,   Fukushima  Pref.,  mean,   (vs.  12.7  uR/hr.  US)      260  to  359  uR/hr.   2.6-­‐3.5  uSv/hr.         I131+  Cs137+  Cs134  MEXT  data   Radiation Exposure to the Population in Japan After the Earthquake

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Cs134  +  Cs  137  on  children s  shoes  

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Environmental  fate  of  radioac%ve  dust   •  Airborne  levels  have  dropped,  soil  levels  remain   high,  while  food  chain  radia%on  can  increase.   •  Radia%on  is  not  uniform.  Some  areas  are  much   higher  than  average,  forming   hot  spots  with  up   to  2.92  nCi/62  radiocesium  in  surface  dust.   •  Cleaned  areas  can  become  recontaminated  by   dusts  from   hot  spots.  Sept.  2011  Noda  City   house  filters:  0.23  nCi  radiocesium  despite   generally  lower  air  levels.   Radiation Exposure to the Population in Japan After the Earthquake

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Long  distance  dust  transport   Ÿ  Boston  air  filters  had   slightly  elevated  total   α  and  β  counts  during   April  and  May  2011.   Ÿ  Sea`le  and  Boston   air  filters  had  posi%ve   autoradiographic   results  during  April   2011.    All  other  USA   filters  were  nega%ve.    

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Conclusion   •  Circular  evacua%on  zones  were  not  protec%ve;   some  evacuees  moved  to  greater  contamina%on.     •  Air  now  cleaner,  but  dusts  remobilize  cesium.   •  Cs-­‐134  and  Cs-­‐137  nearly  ubiquitous  in  Fukushima   Prefecture  and  detectable  throughout  Tokyo;   Co-­‐60  found  in  dusts  from  northern  Japan.   •  US  samples  had  only  two  isolated  Cs-­‐134  and   Cs-­‐137  detec%ons  in  soil;    Am-­‐241  found  offsite   only  in  one  Tokyo-­‐area  dust  sample;  I-­‐131  has   decayed.    

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    The  12  mile  Japanese  evacua2on  zone   appears  inadequate  to  protect  the  public   health.    Is  it  2me  to  reexamine  the  US   Nuclear  Regulatory  Commission  10  mile   planning  zone  for  airborne  accidental   nuclear  releases?  

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