Safeguards and Cooperative Monitoring of Reactors With Antineutrino

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Safeguards and Cooperative Monitoring of Reactors With Antineutrino Detectors Lawrence Livermore National Laboratory Adam Safeguards and Cooperative Monitoring of Reactors With Antineutrino Detectors Lawrence Livermore National Laboratory Adam Bernstein, (P. I. ) Jan Batteux Dennis Carr Celeste Winant Chris Hagmann Norm Madden Sandia National Laboratories California John Estrada (P. I. ) Collaborators Stanford University Giorgio Gratta, Yifang Wang Nathaniel Bowden Jim Lund C. Michael Greaves N. Mascarhenas University of Alabama Andreas Piepke Oak Ridge National Laboratory Ron Ellis LLNL This work was partially performed under the auspices of the US Department of Energy by the University of California, Lawrence Livermore National Laboratory, under contract No. W-7405 -Eng-48.

Project Timeline 1999 -2000 Research into 1 k. T explosion detection Late 2000 Recognize Project Timeline 1999 -2000 Research into 1 k. T explosion detection Late 2000 Recognize futility of this effort – publish paper 2000/2001 2002 Research into reactor monitoring Begin installation at San Onofre Oct. 2003 First data taking Dec. 2003 IAEA interest / experts meeting Now Feb 9 th 2004 Operational for 100 days, 70 events/day Refueling shutdown Summer 2004 800 -1000 events per day LLNL

Properties of Antineutrinos and Antineutrino Detectors • Rates near reactors are high § 1 Properties of Antineutrinos and Antineutrino Detectors • Rates near reactors are high § 1 ton detector, 24 m from reactor core § Not untypical core thermal power = 3. 46 GW § 3925 events/day/ton (100% efficient detector) • Rate and spectrum are sensitive to the isotopic composition of the core • Cost and complexity can be made comparable to that of a few high-end Germanium detectors LLNL

Monitoring Reactors with Antineutrino Detectors A. ~1 cubic meter antineutrino detectors placed a few Monitoring Reactors with Antineutrino Detectors A. ~1 cubic meter antineutrino detectors placed a few tens of meters from the reactor core B. Compare measured and predicted total daily or weekly antineutrino rates (or spectrum) to search for anomalous changes in the total fission rate C. Identify changes in fissile content based on changes in antineutrino rate (“the burnup effect”) A. B. LLNL Measured in previous experiments Rovno quotes 540 kg +- 1% fissile content from shape analysis

What Good Is That ? 1. Detecting unauthorized production of plutonium outside of declarations What Good Is That ? 1. Detecting unauthorized production of plutonium outside of declarations 2. Measuring enrichment of freshly loaded fuel and burn-up or plutonium content of spent fuel destined for reprocessing or storage shipper-receiver difference 3. Checking progress of plutonium disposition, and ensuring burnup is appropriate to core type 4. Monitoring core conversion • An integral, continuous, high statistics, non-intrusive, unattended measurement LLNL

Fission Rates Vary with Time and Isotope Pu-241 U-238 Input fuel enrichment can be Fission Rates Vary with Time and Isotope Pu-241 U-238 Input fuel enrichment can be changed in PWRs § increased plutonium production even at constant power Easy to alter for CANDU (online refueling) LLNL

Detected Antineutrino Rates Vary With Isotope LLNL Detected Antineutrino Rates Vary With Isotope LLNL

The Antineutrino Rate Tracks Inventory Changes The total antineutrino rate changes with the relative The Antineutrino Rate Tracks Inventory Changes The total antineutrino rate changes with the relative U/Pu content of the core n About 250 kg of Pu is generated during the cycle Rate calculation based on a detailed reactor simulation shows an antineutrino rate change of about 10% through a 500 day equilibrium reactor cycle n n This “burnup effect” seen and corrected for in past experiments Modern detectors reach 3% precision The change in antineutrino rate directly tracks the fissile inventory even at constant power LLNL

A 1 Cubic Meter Detector, 10 Meters From PWR Core Counts per day • A 1 Cubic Meter Detector, 10 Meters From PWR Core Counts per day • fuel rods with 20 kg Pu replaced with fresh rods (0 kg Pu) • assumed 3% systematic error • 50% detection efficiency • A standard statistical test can identify the switch with Days > 90% confidence with one month’s data The systematic shift in inventory is reflected by the antineutrino count rate over time LLNL

Inputs Needed to Predict/Extract an Absolute Antineutrino Measurement Core model with the input parameters: Inputs Needed to Predict/Extract an Absolute Antineutrino Measurement Core model with the input parameters: 1. n n n 2. 3. 4. Secondary calorimetric power Pressure Flow rates Boron concentration Inlet temperature total model error 1% (power dominates) * Antineutrino energy density error = 3 % Null result from near-reactor oscillation experiments Well understood antineutrino detector (* from “Estimation of Expected Neutrino Signal at Palo Verde”, Lester Miller, Stanford University, unpublished note) LLNL

The Site, Detector, Signal, Backgrounds 3. 46 GWt reactor Antineutrino detector in “tendon gallery” The Site, Detector, Signal, Backgrounds 3. 46 GWt reactor Antineutrino detector in “tendon gallery” with 1017 n / s per m 2 Installation/testing begun May 2002 data taking began in late September 2003 LLNL

The Underground Experimental Site 20 meter concrete/rock overburden 24 meters from core LLNL The Underground Experimental Site 20 meter concrete/rock overburden 24 meters from core LLNL

Cutaway Diagram of the LLNL/Sandia Antineutrino Detector Currently operational: 2 cells instrumented with 4 Cutaway Diagram of the LLNL/Sandia Antineutrino Detector Currently operational: 2 cells instrumented with 4 pmts; 0. 32 tonnes of Gdscintillator; quasi-hermetic muon veto Gd-doped LLNL hermetic water shield

Detection of Antineutrinos • The antineutrino interacts with a proton producing… – A 1 Detection of Antineutrinos • The antineutrino interacts with a proton producing… – A 1 -7 Me. V positron – A few ke. V neutron – mean time interval 28 sec • Both final state particles deposit energy in a scintillating detector over 10 s or 100 s of microsecond time intervals (depending on the medium) • Both energy depositions and the time interval are measured LLNL

Backgrounds 1. Muon generated neutrons create “correlated” events § § fast neutron proton knock-on Backgrounds 1. Muon generated neutrons create “correlated” events § § fast neutron proton knock-on thermalization and capture within time window energies and time correlation can mimic the antineutrino 2. Neutron and gamma “singles” can fall within the time coincidence window defining the antineutrino event n n gammas from surroundings neutrons from S. F. , activated nuclei from surroundings muon-induced neutrons Background rate ~ a few dozen per day LLNL

Four Variables Define the Antineutrino Signal Variable Eff. T > 100 ( sec) 95% Four Variables Define the Antineutrino Signal Variable Eff. T > 100 ( sec) 95% the time between a muon veto and a cube signal 10 < Tcube < 100 70% the time between the two energy depositions mean = 28 sec (Me. V) 62% (analytic formula) The prompt, positron-like signal (including annihilation gammas) 4 < Edel < 12 68% (MC) the delayed, neutron-like signal from Gd gamma cascade ~80% Events with large asymmetries in PMT energy distribution within a cell ( sec) 3 < Eprompt < 10 Me. V “geometry cut” 1. 022 < E 1 < 7 Me. V, peak at ~3 Me. V 1280 events per day 68 events per day (now) over 800 (with simple upgrades) 100% efficiency LLNL 5% efficiency 30% efficiency and 2 x volume

Event Candidates Since the Last Muon antineutrino-like backgrounds (spallation and capture) more likely to Event Candidates Since the Last Muon antineutrino-like backgrounds (spallation and capture) more likely to occur near a muon Cut on time since last muon: T > 100 sec LLNL

2. Interevent time distribution well fit by e- t/ 28 sec (Capture time set 2. Interevent time distribution well fit by e- t/ 28 sec (Capture time set by 0. 1% Gd concentration in scintillator) Cut on interevent time: 10 < Tcube < 100 sec LLNL

Conclusions That antineutrinos can track burnup and plutonium inventory is firmly established by prior Conclusions That antineutrinos can track burnup and plutonium inventory is firmly established by prior experiments and shortly confirmed by us Detector deployment essential for demonstrating practical utility and potential Main challenges: 1) 2) 3) • • • Controlling detector systematic effects (spectrum error, fiducial error, event containment…) Shrinking footprint (coherent scatter, better IVB detector) Transforming a delicate physics instrument into a robust cooperative monitoring device Must compare to existing safeguards methods and demonstrate that the benefit is worth the cost of deployment LLNL

Literature on Applied Antineutrino Physics Reactor Monitoring Bernstein, A. , Wang, Y. , Gratta, Literature on Applied Antineutrino Physics Reactor Monitoring Bernstein, A. , Wang, Y. , Gratta, G. , West, T. , Nuclear Reactor Safeguards and Monitoring with Antineutrino Detectors, J. Of Appl. Phys V. 91, Num. 7, p 4672, April 2002 Klimov, Yu. et al. The remote measurement of power and energy release using a neutrino method, Inst. Obshch. Yad. Fiz, Russia, At. Energ. , (1994) 76(2) 130 -5, CODEN: AENGAB; ISSN: 0004 -7163 Detection of Antineutrinos for Non-Proliferation M. M. Nieto, A. C. Hayes, C. M. Teeter, W. B. Wilson, W. D. Stanbro, ar. Xiv: nucl-th/0309018 v 1 9 Sep 2003 Conclusion: power and isotopic measurement at 10 -100 m is feasible Explosion Detection A. Bernstein, T. West V. Gupta, An Assessment of Antineutrino Detection as a Tool for Monitoring Nuclear Explosions, Science & Global Security, Volume 9 pp 235, April 2001 B. Conclusion: 1 k. T remote detection is not feasible LLNL




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