AIT-WATCHMAN A Remote Reactor Monitor and Advanced Instrumentation Testbed Christopher Grant On behalf of the WATCHMAN Collaboration
The link between nuclear reactors and nuclear weapons 235 U 85 Kr A source of fissionable material, ! such as 235 U, is required to manufacture nuclear weapons 235 U ! Energy 235 U ! However, 235 U is not ideal due to its rare isotopic abundance (0.7%) and ! the challenge of achieving over 90% 141 Ba enrichment needed for a weapon September 11, 2019 1 TAUP 2019 - Toyama, Japan
̅ ̅ The link between nuclear reactors and nuclear weapons An alternative method, and one that was used by many countries, involves the production of 239 Pu via the transmutation of natural Uranium inside a nuclear reactor 239 Pu 239 Np 239 U #/% ~ 24,000 years #/% ~ 2.4 days " #/% ~ 23 min " " 238 U ! ( ) ( ) + + ' ' Plutonium can be easily separated from Uranium with chemistry September 11, 2019 2 TAUP 2019 - Toyama, Japan
Reactors are operating all over the world S. M. Usman, G. R. Jocher, S. T. Dye, W. F. McDonough, and J. G. Learned, Scientific Reports 5 , Article number: 13945 (2015) September 11, 2019 3 TAUP 2019 - Toyama, Japan
Non-Proliferation Treaty (NPT) – an attempt to mitigate the risk Nuclear Weapon State Ratifiers Nuclear Weapon State Acceders Other Ratifiers Other Acceders or Succeeders Withdrawn Non-signatory These agreements are supported by physical measurements and monitoring systems overseen the International Atomic Energy Agency (IAEA) and the Unrecognized State, abiding by acceders Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) September 11, 2019 4 TAUP 2019 - Toyama, Japan
Can neutrinos be used to monitor distant reactors? Roughly 6 ̅ " # released per fission and ~10 21 fissions per second in a typical 3 GW t power reactor, means that you have ~10 22 ̅ " # per second isotropic emission September 11, 2019 5 TAUP 2019 - Toyama, Japan
̅ Can neutrinos be used to monitor distant reactors? Roughly 6 ̅ " # released per fission and ~10 21 Inverse Beta Decay (IBD): " # + % → ' ( + ) fissions per second in a typical 3 GW t power reactor, means that you have ~10 22 ̅ " # per second isotropic emission 25 km stand-off Water Cherenkov Detector September 11, 2019 6 TAUP 2019 - Toyama, Japan
̅ Can neutrinos be used to monitor distant reactors? Roughly 6 ̅ - . released per fission and ~10 21 Inverse Beta Decay (IBD): - . + 0 → 2 3 + 4 fissions per second in a typical 3 GW t power reactor, means that you have ~10 22 ̅ - . per second isotropic emission 25 km stand-off Water Cherenkov Detector ! " ~ 10 &'( cm ( " + ( Can expect “several” interactions per kiloton of water per day at 25 km distance September 11, 2019 7 TAUP 2019 - Toyama, Japan
̅ Can neutrinos be used to monitor distant reactors? Roughly 6 ̅ - . released per fission and ~10 21 Inverse Beta Decay (IBD): - . + 0 → 2 3 + 4 fissions per second in a typical 3 GW t power reactor, means that you have ~10 22 ̅ - . per second isotropic emission 25 km stand-off Water Cherenkov Detector ! " ~ 10 &'( cm ( " + ( Monitoring capability with antineutrinos studied Can expect “several” interactions in great detail in the following reference: per kiloton of water per day at A. Bernstein, et al., Science & Global Security, 18:127–192, 2010 25 km distance September 11, 2019 8 TAUP 2019 - Toyama, Japan
AIT-WATCHMAN (A dvanced I nstrumentation T estbed – WAT er CH erenkov M onitor of AN tineutrinos ) NNSA’s Office of Defense Nuclear Nonproliferation has funded WATCHMAN R&D since 2012. Mission need: demonstrate and evaluate the viability and scalability of antineutrino-based technologies for remote reactor discovery and monitoring. September 11, 2019 9 TAUP 2019 - Toyama, Japan
AIT-WATCHMAN (A dvanced I nstrumentation T estbed – WAT er CH erenkov M onitor of AN tineutrinos ) NNSA’s Office of Defense Nuclear Nonproliferation has funded WATCHMAN R&D since 2012. Mission need: demonstrate and evaluate the viability and scalability of antineutrino-based technologies for remote reactor discovery and monitoring. Primary Goals: Confirm existence of an operating reactor (ie. determine unknown reactor is • operating in presence of another known reactor) Determine power plant operational status with and without prior knowledge • Demonstrate Gd-loaded water as a scalable detector medium • Enable future technology upgrades: • Water-based liquid scintillator WbLS, Large-Area Picosecond Photodetectors (LAPPDs), techniques for Cherenkov and scintillation light separation, etc. September 11, 2019 10 TAUP 2019 - Toyama, Japan
AIT-WATCHMAN (A dvanced I nstrumentation T estbed – WAT er CH erenkov M onitor of AN tineutrinos ) Hartlepool Reactor AIT-WATCHMAN at Boulby Underground Lab September 11, 2019 11 TAUP 2019 - Toyama, Japan
AIT-WATCHMAN (A dvanced I nstrumentation T estbed – WAT er CH erenkov M onitor of AN tineutrinos ) Hartlepool Reactor has two cores, each operates at a power of 1.5 GW t Hartlepool Reactor for a total of just over 3 GW t 25 km WATCHMAN AIT-WATCHMAN at Boulby Underground Lab September 11, 2019 12 TAUP 2019 - Toyama, Japan
Baseline WATCHMAN Detector Design Gd-doped (0.1%) water Cherenkov detector • ~20 m ~1 kiloton fiducial volume • ~3600 high quantum efficiency, low radioactivity, • 10” PMTs (~20% photocathode coverage) Active outer veto • Multiple calibration system access ports and large • central access plug for future instrumentation Gd-loaded water was chosen because of it’s scalability over other media - it’s the most viable path to a 100 kt – 1 Mt scale detector ~20 m Cutaway view September 11, 2019 13 TAUP 2019 - Toyama, Japan
̅ Advantages of gadolinium loading Gd provides roughly 70% neutron Delayed signal detection efficiency in WATCHMAN (~8 MeV gamma cascade) & Gd & " # % $ & ' ( Prompt signal September 11, 2019 14 TAUP 2019 - Toyama, Japan
Gd-loading demonstrator The Gd-loading and water purification system is based on EGADS ( E valuating G adolinium’s A ction on D etector S ystems). This was built to test Super-K detector materials in contact with Gd-doped water. System is essentially lossless – it extracts Gd, purifies the water, and adds the Gd back in. Water transparency remained within the SK ultra-pure range for over two years. September 11, 2019 15 TAUP 2019 - Toyama, Japan
Backgrounds for reactor monitoring In addition to antineutrinos from the Earth and from other nuclear reactors, the following backgrounds need to be addressed… Detector related backgrounds (random coincidences) γ γ Gammas from radioactivity within detector materials or within the internal water volume September 11, 2019 16 TAUP 2019 - Toyama, Japan
Backgrounds for reactor monitoring In addition to antineutrinos from the Earth and from other nuclear reactors, the following backgrounds need to be addressed… Detector related backgrounds Cosmogenic related backgrounds (random coincidences) (correlated events) " 9 Li γ " γ # # Gammas from radioactivity within Fast neutrons from nearby Long-lived radionuclides produced by detector materials or within the rock muons spallation ( 9 Li and 8 He) that undergo internal water volume $ -decay with neutron emission September 11, 2019 17 TAUP 2019 - Toyama, Japan
Background Measurements Neutron energy spectrum was measured by MARS Plastic at three different depths in Kimbleton Underground Multiplicity And Recoil scintillator + Research Facility (KURF). The data was compared Spectrometer (MARS) GdO 2 (1%) with an existing model and other measurements. 12 layer detectors PRELIMINARY Neutron converter - 3,560 lbs of lead in a steel table September 11, 2019 18 TAUP 2019 - Toyama, Japan
Background Measurements Watchboy was deployed at the same depth as WATCHBOY Detector MARS. FLUKA simulations of neutrons in WATCHBOY, using the MARS measured neutron energy spectrum as input, agree with the data. ] -1 Data Rate [day FLUKA 10 Geant4 1 1 − 10 PRELIMINARY 2 − 10 2-ton Gd-loaded water target 2 3 4 Neutron multiplicity surrounded by pure water veto September 11, 2019 19 TAUP 2019 - Toyama, Japan
Boulby Underground Laboratory This facility is well-established, hosting a variety of low- background particle physics experiments and other multidisciplinary projects Depth of 1.1 km (2805 mwe) Cleanliness in the underground lab will reduce the impact of dust and other environmental contamination September 11, 2019 20 TAUP 2019 - Toyama, Japan
Estimated sensitivity for the baseline design Summary of background budget Component Events/week Core-1 4.2 Core-2 4.2 WATCHMAN simulations use World reactors 1.5 combination of customized Accidentals 0.9 rat-pac with BONSAI for Fast neutrons* 0.6 event reconstruction Radionuclides 0.1 Total 11.3 *Fast neutron sims with FLUKA still in progress September 11, 2019 21 TAUP 2019 - Toyama, Japan
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