Radiation Control Bureau

New Las Conchas Fire Air Sample Monitoring Information

DOE RAP Page

The air sample monitoring units were set in various locations and managed by the DOE Radiological Assistance Program as requested by the New Mexico Environment Department.  The air sample monitoring and locations were validated for accuracy by the New Mexico Environment Department, Radiation Control Bureau.

The air monitoring results for 137-Cesium, 239-Plutonium, and 241-Americium are below air effluent Concentrations as specified in Table II of 20.3.4.461 NMAC, and are in compliance with "Dose Limits for Individual Members of the Public" 20.3.4.413 and "Compliance with Dose Limits for Individual Members of the Public" as specified under 20.3.4.414 NMAC.

Air effluent concentrations are applicable to the assessment and control of dose to the public and are equivalent to the radionuclide concentration which, if inhaled over the course of a year, would produce a total effective dose equivalent of 0.05 rem.  Which is less than the 0.1 rem per year public dose limit.

1-MDA, Minimum Detectable Activity, is based on natural background, the time period of the measurement and the air sample monitoring volume (i.e. cubic meters) and was provided by DOE Radiological Assistance Program. The MDAs were calculated using the equation:

MDA = {3.29 [Rb Tg (1+Tg/Tb)]^0.5 +3}/(K Tg) where Rb = background count rate (detector specific) Tg = sample count time (usually 3600 s) Tb = background count time (usually 50,000 s) K = efficiency * alpha yield (1 for Pu & Am, 0.35 for Bi-212)

There will be slight variations in the MDAs due to different backgrounds for the detectors.  Also, the MDAs for the preliminary results will be much higher as the contribution to the background for the Pu-239/240 and Am-241 regions from Bi-212 alpha straggling was estimated and included in the calculation.  In general the MDA for the preliminary results was 0.01 nCi and for final results, without Bi-212 interference was 0.002 nCi.

2-NDA (No Detectable Activity), means there is no measurable activity above the 1-MDA.

• Location  Description	City	Elevation (ft)	Actual Corrected Flow (cubic meters)	Air Sample Start Date	Air Sample Stop Date	1-MDA 239-Plutonium pCi/m3	2-NDA 239-Plutonium pCi/m3	1-MDA 241- Americium  pCi/m3	2-NDA 241-     Americium  pCi/m3
  Holy Cross Hospital	Taos	7096	447.1	6/29/2011	6/30/2011	0.00089	NDA	0.00067	NDA
  Fire Station #2	Taos	6994	468.0	6/29/2011	6/30/2011	0.00064	NDA	0.00064	NDA
  Embudo Clinic	Embudo	5929	399.6	6/29/2011	6/30/2011	0.00050	NDA	0.00050	NDA
  Embudo Valley Library	Dixon	6091	371.6	6/29/2011	6/30/2011	0.00054	NDA	0.00054	NDA
  New Mexico Environment Dept.	Las   Vegas	6594	448.0	6/29/2011	6/30/2011	0.00045	NDA	0.00045	NDA
  El Valle Residence	El Valle	7790	955.5	6/29/2011	6/30/2011	0.00010	NDA	0.00010	NDA
  Chimayo Residence	Chimayo	6189	791.0	6/29/2011	6/30/2011	0.00051	NDA	0.00038	NDA
  Hondo School (Incident Command Post)	Hondo	6486	1719.2	6/29/2011	7/1/2011	0.00052	NDA	0.00052	NDA
  Hondo School (Incident Command Post)	Hondo	6486	348.7	6/29/2011	6/30/2011	0.00115	NDA	0.00086	NDA