Radon Reference Facility at Bowser-Morner, Inc. AMUG Meeting Las Vegas May 4, 2010 Phillip H. Jenkins, PhD, CHP

Radon Reference Facility What We Do Calibration of Rn and RDP measuring devices Spiking of Rn measuring devices Blind Performance Tests for clients maintaining certification (or licensing) with: NEHA/NRPP NRSB NJ, PA, ME, RI CNSC

Radon Reference Facility Product Testing Research Consulting Training What We Do

Calibration of Rn & RDP Devices Calibration, quality assurance testing, product development, etc. requires exposing devices to known and controlled atmospheres of radon and/or radon decay products. The design of the atmosphere, or radon chamber, may vary significantly depending on the intended use.

Radon Chamber Design More Complicated Than You Might Think Size of chamber? Recirculating or Pass-Through? Stagnant or air flow, and if so how much? Temperature and humidity control? Source of radon? How to monitor the radon concentration?

A Little Radon Chamber History 1980 When we were designing the radon chamber at Mound, we toured and took ideas from chambers at: EML, New York, NY EPA Montgomery, AL Bureau of Mines, Denver, CO University of Toronto

A Little Radon Chamber History 1980 Chamber designs varied greatly: EML was a large walk-in chamber with recirculating flow. EPA Montgomery was a single-pass design made from four plywood sheets to form a 8 x 4 x 4 foot box. BOM s chamber was held at high concentrations, where others were lower environmental levels. None had temperature and humidity control at that time.

A Little Radon Chamber History Source of Radon The chamber must have a source of radon as input. Chambers used several types of sources: Radium in solution, air bubbled through to collect radon (EML). Uranium Ore, Mill Tailings or Phosphate Slag Soil Gas Commercially available radon sources from Pylon; one-shot sources, flow-through sources.

A Little Radon Chamber History Mound design: 1980 Walk-in chamber, 9 x 9 x 8 ft, with antilock room. Recirculating flow through an external environmental chamber for temperature and humidity control. Radium in solution with bubbler (like EML).

A Little Radon Chamber History 1980 s Soon after Mound chamber was built: EML retrofitted its chamber for temperature and humidity control. EPA Montgomery built two large walk-in chambers with temperature and humidity control. Large chamber built at DOE s Grand Junction facility with temperature and humidity control. EPA Las Vegas built a large walk-in chamber with temperature and humidity control (ultimately had three chambers).

A Little Radon Chamber History 1986, DOE s need for the chamber at Mound was ending just as the need within the private sector was beginning. Mound chamber was used for about 3 years to support private efforts (manufacturers, laboratories) for calibration, product development, quality assurance testing. An incident ended the operation of the chamber at Mound in 1989. By that time there were private companies that were operating chambers.

A Little Radon Chamber History 1991, I left Mound and started designing and building a chamber at Bowser-Morner, Inc. I toured (again) the chambers at the two EPA facilities. I used ideas from EML, Mound and the two EPA facilities. Today, the only chambers (that I know of ) in the US government are the one at EPA Las Vegas and one at ORNL.

A Little Radon Chamber History Bowser-Morner chamber design: Large walk-in room, 12 x 12 x 9 ft (same as EPA Las Vegas) Recirculating flow Source, two flow-through Pylon Ra-226 sources External environmental chamber for temperature and humidity control (same as Mound) Designed to minimize the amount of radium to purchase and license, as well as the amount of radon that would be released to the environment

Bowser-Morner Radon Chamber

Chamber Layout (Similar to EPA/Las Vegas) 2.54 m 1.37 m 3.84 m (12 ft) Hgt = 2.71 m Vol = 9.45 m 3 3.76 m (12 ft) Air Lock Height = 2.71 m (9 ft) Volume = 39 m 3

Bowser-Morner Radon Chamber

Air Lock Chamber Conditioned air is blown from the environmental chamber, through the radon chamber and back at a rate of 100 cfm. Air velocity in chamber is 10 20 fpm. Rn Conditioning Chamber 8-ft 3 Environmental Chamber Radon is continuously pumped into return leg to environmental chamber. Two chambers form a closed loop.

Radon Sources 238 kbq 0.0064 mci 500 kbq 0.0135 mci

Radon Measurement System Three Eberline SACR-5 Photomultiplier Tubes/Scintillation Cells Tennelec Electronics and Counting System (to be replaced with more modern equipment)

Environmental Chamber

Chamber Interior

Intercomparisons EPA Las Vegas Lab Fills my scintillation cells from NIST traceable 226 Ra source. At Bowser-Morner I analyze the cells and report results to proficiency programs. At Bowser-Morner The same cells are used to take measurements from chamber and compare with continuous monitoring system.

Atomizer from article by Leong, Wang, Stukel & Hopke We used an atomizer of this design at Mound to generate an aerosol in the chamber air for radon decay product work. When EPA Las Vegas lab built their first chamber, they borrowed this idea from Mound. In the early 90s I borrowed the idea back from EPA Las Vegas lab to use at Bowser-Morner.

Atomizer

Aerosol Generator Atomizes salt solution. Aerosol stream passes through heated tube then across desiccant, then into chamber.

Condensation Particle Counter TSI Model 3022A

RDP Monitor Alpha Nuclear Used as a continuous gross alpha counter. Calibrated to RDP concentration upon each use through comparisons with grab RDP measurements.

Intercomparisons for RDPs EPA Las Vegas Lab Side-by-side measurements with EPA personnel. At Bowser-Morner I analyze my results and report to proficiency programs. At Bowser-Morner Grab sampling during every test. Continuous monitor used for gross-alpha only. A least squares procedure used to fit the data to the grab measurements (calibrating the monitor for each use).

Personal Alpha Dosimeter (PAD)

PAD Charging Unit at Mine

Personal Alpha Dosimeter (PAD)

PAD Detector Head

Personal Alpha Dosimeter (PAD)

Personal Alpha Dosimeter (PAD) Stall pressure is measured before and after each exposure.

Personal Alpha Dosimeter (PAD)

From CNSC Regulatory Standard S-106 Range of Measurement Overall Accuracy (95% Confidence) 0.05 WLM (177 µj h m -3 ) to < 0.10 WLM (354 µj h m -3 ) +100% / -50% 0.10 WLM (354 µj h m -3 ) +50% / -33% Range of Measurement Overall Accuracy (95% Confidence) 0.05 WL (1.03 µj m -3 ) to < 0.10 WL (2.08 µj m -3 ) +100% / -50% 0.10 WL (2.08 µj m -3 ) +50% / -33%