Radiation and Magnuson Park Al Conklin Senior Health Physicist Office of Radiation Protection

Department of Health  By statute (RCW 70.98) Department of Health is the Radiation Control Agency.  Mission: to protect and improve the health of people in Washington State.

Me  In radiation safety for 38 years (28 as a health physicist)  Studied health effects of plutonium  Regulated nuclear waste management and nuclear facilities  Performed Dose reconstruction for Hanford downwinders  Handled public health inquiries about Chernobyl, Fukushima and Hanford.  Currently a radiation instructor for first responders and health care providers.

History of Radium  A natural isotope existing in nature; decaying from uranium.  When isolated, it glows in the dark.  In 1915, a radium paint was invented and used on WW1 aircraft gauges so pilots could fly at night.  Became a standard for decades for clock faces, dials and gauges.  Its danger was discovered in the 1920s when radium dial painters died from ingesting radium on their brushes.

Exposure Pathways for Radium  Swallowing substances contaminated by radium.  Radon gas given off by Radium– the most significant pathway  Measured as picocuries – or pCi – per liter of sampled air. ( 1 pCi = 1/ 1 trillionth of a curie)  External gamma exposure measured in units of rem or microR/ hour which equals 1/1 millionth of a rem

Radon Measurements in Buildings EPA Standard = 4.0 pCi/L N Sand Point Way Controls 3 locations tested All 3 tests less than 0.3 pCi/L Mountaineers Bldg 11 locations tested All tests – less than 0.3 pCi/L 4 locations tested All tests – less than 0.3 pCi/L All tests were less than detectable pCi/liter Not enough radium in these buildings to cause any measurable radon concentrations.

N Building 27 Shed Building 2 Fence Radiation Surveys of Perimeter Fence Grumbles Conklin microR/hour Gamma Radiation – Outside Bldg 27 Prior to Clean-up

Bldg. 27 (Arena Sports) Local Radiation Surveys for comparison Location Results 1 8 to to to to to to to to to to to to Gamma Radiation- Neighborhood microR/hour

Background Radiation Surveys in Seattle Magnuson Park Lake City Way Woodland Park 6 to 8 Queen Anne Hill 8 to 10 Pike Street Market Park 4 to 7 Safeco Field 7 to 9 microR/hour 4 to 6

External radiation exposure  Even before clean-up, exposure to radiation in the clean-up are was equivalent to area background levels.  THEN WHY CLEAN IT UP?  Some spots were significantly above backround  Clean-up requirements are very strict and conservative requiring clean-up to levels too low to accurately measure with instrumentation  The standard is based on a calculated level; it’s too low to be measured.

What does long term risk mean?  We know there is risk from higher exposures.  We can’t see it at extremely low exposures like the levels seen here. There is no reliable data.  However, there are also no reliable data that proves the opposite.  Neither can be proven --- so, we based dose limits and clean-up standards assuming the risk is real, though we can, theoretically, calculate a risk all the way to a single atom.

Risk, continued  There has to be a clear pathway for exposure.  It must be conservative, but also must be realistic.  You have to account for:  different kinds of radiation (alpha, beta and gamma)  A reasonable maximum time of exposure (no one will sit on a spot in the elements for an entire year)  A clear defined pathway (ingestion, inhalation, external exposure)  There is no dose if a person is not exposed to a radiation source.

We can compare risks  Radiation scientists strongly caution against trying to calculate actual risks from such low standards.  However, since the Navy scenarios are based on the theory of effects at low doses, we’ll go with that.  But, it’s important to put that calculated risk in perspective with other similar radiation exposures.  This means that if the risk from one radiation source is true, it has to be for the others.  The body cannot tell the difference between nature caused and man caused radiation.

Putting Numbers in Perspective Recreation in the Clean-up area* (from residual radium) 0.02 mrem/hr Living in a brick building 0.01 mrem/ hr One cross country flight 4.0 mrem/trip One chest X-Ray10.0 mrem/X-Ray Dose from Radon – Seattle 0.22 mrem/day Dose from Radon – Spokane 4.3 mrem/day Natural gamma background-Sandpoint neighborhood 0.01 mrem/hr Eating one banana 0.01 mrem/banana *Based on the EPA clean-up value of 15 millirem per year for any residual radium.

Translation – based on life styles, individuals’ doses can vary significantly  If you spend 200 hours at the clean-up site, you would receive 1/200 th of the radiation dose as you would get from 1 hour of flying in an airliner. (cosmic radiation)  For each hour you spend there, the radiation dose is the same as eating 2 bananas, (natural potassium is slightly radioactive).  The average annual dose from radon in:  Seattle is 80 millirem (doses vary)  Spokane is 1600 millirem (doses vary)  The 15 millirem standard is only theoretical but is lost in background doses from just living on the earth  We are talking about very low exposures here.

Clean-up work involving DOH  Building 27  Contractor cleaned and reported surveys showing no residual contamination.  DOH would normally verify surveying 10% of the locations done by the contractor.  However, our inspectors chose to go beyond those survey points. Their findings:  Building was not clean. They found additional hot spots in corners, cracks, cubby holes, staircases, etc.  Contractor removed more material, requiring a new verification survey. Funding has been identified to conduct verification surveys.  Building 2 is releasable.

This park will be a safe place to play, work or attend school Questions may be directed to: Al Conklin (360) Conclusion