There are adequate supplies of technologies that can be integrated into radiation detectors for homeland security and scientific research as an alternative to helium-3 gas, which is suffering from a severe shortage that only became apparent in 2008, the Government Accountability Office (GAO) says in a recent report.
The three alternative neutron detector technologies—boron-10, boron trifluoride and lithium-6—have not yet been fully tested for these applications although field testing of radiation portal monitors (RPM) using boron-10 lined proportional detectors has been completed, says the report, Neutron Detectors: Alternatives to using Helium-3 (GAO-11-753). The report cites DHS officials as saying that boron-10 –based detectors may be available for domestic RPM deployments during FY ’12.
“GAO estimates this neutron detector is sufficiently mature such that a decision to use it in forthcoming portal monitor deployments can be made with confidence that the portals will perform as required,” the report says.
The report says that in February 2011 the Domestic Nuclear Detection Office awarded contracts to five vendors to acquire RPMs, one based on boron-10 and the rest on lithium-6. This year the agency is doing performance testing and limited environmental testing on these detectors.
Separately, DNDO completed performance, environmental and system tests using a boron-10 proportional detector and completed field tests in July, with preliminary results showing the RPM designed successfully passed all test objectives for use at a port of entry, GAO says. The Defense Department has acquired 12 RPMs that use boron-10 detectors and plans to conduct field tests this year, the report says.
GAO says that this RPM based on boron-10 is at a technology readiness level (TRL)-7, with TRL-9 the most mature, and could be at TRL-8 once it has been deemed to successfully complete the field tests.
The report says that full tests of the boron trifluoride-based technology are still needed that although performance testing at Pacific Northwest National Laboratory showed these detectors could provide a suitable replacement for helium-3. GAO puts this technology at a TRL-5 for use in RPMs.
Several detectors based on lithium-6 from three different vendors over the summer passed Department of Homeland Security performance tests and limited environmental tests, the report says. Successful completion of the technology in an operational environment would get it to a maturity level of TRL-7, GAO says. It adds that additional environmental and system tests could be done in less than four months.
The report also says that there are more than 30 federally funded research and development programs underway that could create more alternative detector technologies, some of which could be ready for integration into deployable detector systems in less than two years, further reducing demand for helium-3.
GAO says the costs of boron-lined detectors and lithium-6-based detectors are high but as with the boron trifluoride detectors, all meet required detection efficiency and required gamma radiation discrimination.
Based on the recent developments of the alternative detector technology, GAO says that “Federal agencies should therefore be able to continue the deployment of radiation portal monitors with minimal additional program delays and with minimal use of additional helium-3.”
Two concerns with the boron-10 and lithium-6 technology is that they are export controlled materials, GAO says. Boron trifluoride is a hazardous material, the report says.