Our Portfolio: Characterization & Sensors Projects

CMST Index | Characterization & Sensors | SCFA

BetaScint Fiber-Optic Sensor for Detecting Strontium-90 and Uranium-238 in Soil

Information
Resources

Technology
Summary Sheet

Technology
Deployment
Fact Sheets:
AR #839
AR #841
AR #1379
AR #2361
AR #2437

Innovative Technology
Summary Report

Images

Commercial Products

 

Tech ID: 70
Project Overview
 The BetaScint(TM) sensor is designed to measure beta emissions from Sr-90 and U-238 in soils. The sensor is 150×35×8cm; it can measure contamination of the soil surface or of a soil sample spread over a tray. The time required is 20 minutes per sample at a cost of $30-55, compared with 1-4 weeks and $150-275 for laboratory analyses. The BetaScint sensor works as follows: (1) beta particles (electrons) emitted by radioactive soil contaminants excite electrons in fluorescent compounds doped into plastic fibers in the layers of the sensor; (2) these give off light (scintillate) when the fluorescent molecules lose energy and return to their ground state; (3) scintillations are counted by photodetectors to determine beta radioactivity of the soil sample. Sample processing is limited to drying and sieving soil samples to remove rocks and excessive organic matter. The BetaScint system is easy to operate and does not generate secondary wastes.
Technology Description
The BetaScint(TM) sensor technology is intended for screening sampling to determine the extent of excavation needed to remove Sr-90 contamination as work progresses and for confirmation sampling to verify that Sr-90 contaminated wastes and adjacent Sr-90 contaminated soil have been removed at the end of excavation. The BetaScint sensor is designed to measure beta emissions from Sr-90 and U-238 in soils on-site with a short (20 minute) turn-around time at a cost 60%-90% less than off-site laboratory analyses. The sensor can measure contamination of the soil surface or of a soil sample spread over a tray. The basic principles of the BetaScint(TM) technology are as follows: (1) 2.3MeV beta particles (electrons) are emitted by the radioactive decay of Yttrium-90 or Protactinium-234m (equilibrium radioactive decay daughters of Sr-90 and U-238 respectively) on contaminated soil surfaces; (2) the beta particles excite electrons in the two 1mm ribbons and one 0.5mm ribbon of plastic scintillation fibers that make up the sensor; (3) the excited fluorophores in the plastic fibers give off light (scintillate) when they lose energy and return to their ground state; (4) scintillations from the plastic fibers are counted by photodetectors; (5) when background counts are eliminated, the number of scintillations counted in a given time is proportional to the average beta radioactivity of the soil sample. BetaScint can measure only total beta activity (combined Sr-90 and U-238 concentrations); constituent identification can be achieved by pairing BetaScint with on-site gamma spectroscopes. Detection limits are around 1 pCi/g above background, comfortably less than the LEHR screening criterion of 10 pCi/g, for example.

Return to Top