Cooperative Monitoring of Reactors Using Antineutrino Detectors – Report on Progress Adam Bernstein, (P. I.)

Cooperative Monitoring of Reactors Using Antineutrino Detectors – Report on Progress

• Adam Bernstein, (P.I.)

• Celeste Winant

• Chris Hagmann

• Norm Madden

• Jan Batteux

• Dennis Carr

How Much Plutonium is There in the World ?

Civil Plutonium Flows are Monitored by the International Atomic Energy Agency (IAEA): How Do They Do It ?

What Good is Antineutrino Monitoring?

• Verify declarations of plutonium content with a direct measurement  shipper-receiver difference

• Early detection of unauthorized production of plutonium outside of declarations at tens of kg levels

• Checking progress of plutonium disposition, and ensure burnup is appropriate to core type

“The Burnup Effect”: the Antineutrino Rate Varies with Time and Isotope

The Simplest Operational Implementation

Monitoring Reactors with Antineutrino Detectors

• 1 ton antineutrino detector placed a few tens of meters from the reactor core

• Compare measured and predicted total daily or weekly antineutrino rates (or spectrum) to search for anomalous changes in the total fission rate - normalize with thermal power measured to 1% accuracy

• Extract changes in fissile content based on changes in antineutrino rate

• Measured in previous experiments
• Kurchatov/Rovno quotes 540 kg +- 1% fissile content from shape analysis
• We expect sensitivity to a change of a few tens of kilograms of fissile materials (Pu  U) is possible with a relative measurement
• ‘rate + shape’ analysis could eliminate need for normalization with reactor power

Benefits and Obstacles for Adoption by the IAEA

• Antineutrino monitoring could provide:

• An inventory measurement good to tens of kg early in the fuel cycle

• Reduced frequency of inspector visits ($9000 per inspector-day)

• Reduced reliance on surveillance and bookkeeping But:

• Cost and footprint must be small

• Reactor layout must allow for deployment with overburden

• IAEA has other pressing safeguards problems

Testing the Idea at a Reactor Site

Events that mimic antineutrinos (Background!)

• Antineutrinos are not the only particles that produce this signature

• Cosmic ray muons produce fast neutrons, which scatter off protons and can then be captured on Gd

• Important to tag muons entering detector and shield against fast neutrons – overburden very desirable

Finding the Energy Scale using ‘Singles’ Data

• Full energy peaks not available in this small detector

• We must compare data to a simulation to extract an energy scale

• Model includes:

• Assumed U/Th/K concentrations
• MCNP for particle transport
• z dependence of light collection
• gaussian smearing to account for photostatistics

Antineutrino Selection Criteria

• 4-cell Prompt Energy > 3 MeV → 0.6 (analytic)

• 4-cell Delayed Energy > 4 MeV → 0.4 (n/ transport MC)

• 10 < Interevent Time < 100 sec → 0.7 (analytic)

• Time Since Last Muon >100 sec → 0.94 (deadtime)

• Abs((pmt1-pmt2)/(pmt1+pmt2))<0.4 → 0.85 efficient (GEANT)

The Time Distributions Behave As Expected

Energy Distributions Are Also Consistent With Antineutrinos

The Delayed Energy Spectrum via Subtraction

Daily Power Monitoring Using Only Antineutrinos

A Preliminary Indication of the Burnup Effect

Next Steps

• Continue data taking through the next shutdown

• Exploit recently installed LED and charge injector to study stability

• Show the IAEA how the method fits into the current safeguards regime

• Pursue worldwide collaborations – France, Brazil, Russia… deployment in a country subject to safeguards would be an important ‘psychological’ breakthrough