Antineutrino detection has been demonstrated to provide verification of commercial reactoroperation and fissile material content for nuclear safeguards. Previous antineutrino detectorshave required underground deployment locations and significant passive neutron and gammashielding to reduce backgrounds from cosmic-ray showers. The resulting requirement for aseveral square-meter, belowground deployment location might limit the application of thisotherwise non-intrusive monitoring technology to the existing reactor fleet.In this submission, we report on the recent development and deployment of a technology whichhas the potential to dramatically reduce the footprint of antineutrino detectors and to allowoperation above ground. We have developed a segmented scintillation-based design that usesintegrated readout of standard organic plastic scintillator and ZnS:Ag/~6LiF neutron detectionscreens. This design provides unambiguous particle identification of the positron and neutronfinal-state products of an antineutrino interaction, thereby allowing for significant rejection ofbackgrounds. A small 4-unit prototype has been deployed at the San Onofre Nuclear GeneratingStation in both above and below ground locations. After initial testing inside of a passive shield,we have found that the added background rejection allows this detector technology to functionwithout the need for external passive shielding. This has allowed our overall footprint to besubstantially reduced: the detector and associated equipment are fully contained within a singleelectronics rack. Our estimates suggest that a full system that is able to fully address the needsof a reactor monitoring regime would require only a modest increase in the detector mass anddeployed footprint.
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