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Amanda Porta – CEA Saclay TAUP 2009
Reactor Neutrino Detection for Non Proliferation with the NUCIFER Experiment
A. Porta for the NUCIFER collaboration
NUCIFER Collaboration: CEA-DSM, Saclay, France; CEA-DAM, Bruyères-le-Chatel, France; IN2P3-Subatech, CNRS/IN2P3, EMN, Université, Nantes, France;
APC, Paris, France
Index:● Reactor neutrinos
● Remote control of nuclear reactors ● The NUCIFER project
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Reactor neutrino emission and detection
e
Emission: -decay of fission products
● ~ 6 / fission ● ~1021 /s for a 1 GW
el reactor
e
-decaysfission
ν e + p → e+ + n
Prompt e+ signalEprompt = Eν -(Mn-Mp)+me
Delayed n captureafter thermalization ~ 30 s
Detection:
Threshold: Mn - Mp + Me = 1.8 MeV
1ton target @ 25m of 1GWel reactor gives ~4600 int./day ➞ 1% stat within 2 days
Miniature detector and high statistical precision
Detection reaction cross section ~10-43 cm2
→ typical detector masses: many 10 tons - some ktons
n rich stable
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2.84 MeV2.94 MeV< Eν >
(Eν >1.8 MeV)
≈ 2.76 10-43 cm2
≈ 3.2 10-43 cm2
< σ ν int >
1.451.92ν / fission
(Eν >1.8 MeV)
198.9 MeV193.5 MeVE / fission *
239Pu235U
* E=Edep
-E
N νU
N νPu= fission×
U
fission× Pu
E fission Pu
E fission U~1.6
Pth = cst
Dependence of neutrino flux on fuel composition.
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Non-proliferation: IAEA interest
IAEA specifications for neutrino detectors:● Safe and robust● Compact● Easy to be used● Remote controlled
In October, the IAEA Novel Technologies group has host a meeting in Vienna to chart a path towards a safeguards deployment based on neutrino detection.Outcomes → R&D recommendation and possibility of becoming officially part of AIEA development program
What neutrinos can say:● flux directly related to the fission process in the core, i.e. to the core composition● Real-time information on isotopic fission rates● flux cannot be controlled or shielded ● Non-intrusive, continuous and remotely operated method
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SONGS1 measurement
Reactor Power (%)
-20
0
20
40
60
80
100
Date
06/2005 10/2005 02/2006 06/2006 10/2006
Detected Antineutrinos per day
0
100
200
300
400
500
Predicted rate
Reported power
Observed rate, 30 day average
Cycle 14Cycle 13outage
Cycle 13
Removal of 250 kg 239Pu, replacementwith 1.5 tons of fresh 235U fuel
LLNL/Sandia Antineutrino Detector,Bowden @ AAP 2007
LLNL/SANDIA detector results:
● 1.1 GWel ➞ ~1021 ν /s● Target: 0.64 t of Gd doped liq. scint. ● Detection efficiency ~11%
Det
ecte
d ne
utri
no c
andi
date
s per
day
Rea
cto
r P
ow
er
(%)
Nν=γ [1kt ]P th
Fuel composition (time dependent)
Detector (constant)
Neutrino rate:
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The NUCIFER detector
● 16 PMTs of 8 inch
● 25 cm acrylic buffer
● Target: 0.85 m3 Gd doped liquid scintillator
1.2 m
1.8
m
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Simulated detector response
Number of photoelectrons generated by e+ of 1 MeV with selected initial positions on z axis:
z scan
PM
Ts
Target center
PM
Ts
Target center
Detection efficiency of neutrons of 20 KeV generated in selected positions on z axis (energy threshold = 4MeV)
Energy resolution @ 4 MeV : 6 %
detection efficiency: ~ 50%
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● 2009: detector construction● 2010: commissioning at OSIRIS research reactor (CEA-Saclay)● End 2011: calibration at ILL (Grenoble) research reactor (pure 235U spectrum)● Late 2012: NUCIFER at a Nuclear Power Station
NUCIFER road-map
OSIRIS: Pth=70 MW
the core
-11m P.Durande-Ayme @ TRTR-IGORR joint meeting 2005
7 m
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with plastic scintillator
n with NE213
Nev
Background measurement at the research reactors
SB=
R
Racc
SB=
R
Rcor
Accidental background (+n capture): Correlated background (p recoil+n capture):
To be improved with PSD
at Osiris: attenuation respect to surface ~2.7
Ni
FeAl
Co K
Radiative capturesRadioactive elements with Ge
= 0.56 = 0.25
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Background reductionShielding:● Active -veto● 14 cm of Polyethylene → n shielding● 10 cm Pb → shielding
PSD in organic liquid scintillators: due to long-lived decay of scintillator light caused by high dE/dx particles
Q tot
Q t
ail
n
Very preliminary
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2 fixed fuel compositions (in fraction of fissions per isotope):End of the cycle: 235U=0.5 239Pu=0.5Beginning of the cycle: 235U=0.7 239Pu=0.3
~7 days of data taking (for NUCIFER @ 25 m from 1GW
el reactor)
Null Hypothesis of 2 statistical test: the two compositions induce identical phe spectra:
➢ Rate change: Hp rejected with 99.99 % C.L. ➢ Shape change: Hp rejected with 25% C.L.
Simulation of response to core evolution
Following the burn-up:
Reactor emitted spectrum from MURE + BESTIOLE simulation package
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NUCIFER @ 25 m from 1GWel PWR:
with 2 relative measurements of 15 days of data before and after the reactor stop the retrieval of 80 kg of Pu can be seen with 75% C.L. and 4% probability of false alarm.
Sensitivity to Pu content
+
+
time
Det
ecte
d
rate
Reactor stop
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Conclusions
Neutrino detection is a promising method for reactor survey: ● The challenge is a small detector close to the earth surface
● Accurate simulations of reactor neutrino spectra and detector response
➔ If we go at some 10 m from reactor core with a 1 ton detector we can have a good statistic within few days
➔ Accurate measurements to optimize the background shielding and background rejection method
First event expected for beginning 2010!!!!
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Back-up slides
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SONGS detector deployed at the San Onofre Nuclear Generating Station
• 3.4 GWth ➞ ~1021 ν /s• 3800 int. expected per day in 1m3 liq. scint. target • Dimensions: 2.5x3 m2, 0.64t of Gd doped liquid scintillator,
8 PMTs, water shielding, plastic muon veto• Detection efficiency: 11%• Low cost and robust detector• Automated, non intrusive measurement
Back up slide: the LLNL/Sandia detector
NIM A 572 (2007) 985, J. Appl. Phys. 103, 074905 (2008)
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Back up slide: Power measurement
35% constant E resolution
Pth = cst !
Normalized to T=1day
1+k(t) parameter: simulation of 1 year cycle of a PWR reactor @ Pe = 0.9 GW: 10% decrease
Yu.V.Klimov et. al., Atomic Energy, vol. 76, n. 2 (1994)
Reactor power in % of 1375 MW
Rat
e p
er 1
05 sec
nν /(1+k) = γ Wth
γ =0.733 ± 0.005 evt./MWth
Proportionality to Pth after burn-up correction
Rovno experiment results:
Integral flux measurement over 1 cycle is a cross check of fuel composition and thermal power declared in the books by the Power Station
Nν=γ [1kt ]P th
Fuel composition (time dependent)
Detector (constant)
Neutrino rate:
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Back up slide: the Rovno experiment (1986)
PWR Rovno reactor (Russia)1.3 GWth
~1m3 of mineral oil + 0.5 g/l Gdd= 0.78 g/cm3 84 PMT, ε det – ~50%
Shielded by: 15 cm of steel, 50 cm of bored polyethylene liquid scintillator active shielding on the top
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Back up slide: neutrino energy spectrum from 235U and 239Pu
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OngoingHP-GeTawainTexono
On site R&DLSAngra, BrazilANGRA
In preparationLS @ 120 mweRovno, RussiaROVNO new
In preparationLS @ 120 mweChooz, FranceDouble Chooz
Funded1.2t LSFranceNUCIFER
Ongoing1t LS @ surfaceJoyo - JapanKASKA
OngoingHP-GeSan Onofre, USSONGS
OngoingGd-H20San Onofre, USSONGS
OngoingPS @ 20 mweSan Onofre, USSONGS
Done - Pth & Burnup0.5t LS @ 20mweSan Onofre, USSONGS
Done - Pth & Burnup1t LSRovno, RussiaROVNO old
StatusSetupSiteExperiment
Back up slide: worldwide effort
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Back up slide:Liquid scintillator: Eljen Technology EJ335-0.1/0.5%
COMPONENT % WT.1,2,4Tlimethylbenzene < 40%USPWhite Oil >60%Organic f1uors <0.2%
Physical propertiesBOILING POINT > 200°C (390°F)MELTING POINT Not applicableSPECIFIC GRAVITY (H20=1) 0.87 at 20°C.VAPOR PRESSURE (mm Hg) < 1 mm @ 20°C (68°F)VAPOR DENSITY (air =1) approx.4PERCENT VOLATILE BY VOLUME (%) <40%EVAPORATION RATE (butyl acetate=1) very slowSOLUBILITY IN WATER Nil
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Back up slide: testing the PSD of NUCIFER scintillatorFacility set-up
Method:
neutrons
gammas
Results:
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Back up slide: Reactor neutrino simulation
deployed by Double Chooz Collaboration
Inputs: • n flux • initial composition • core geometry
Monte-Carlo Simulation:Evolution Code MURE
Inputs: nuclear database exp. spectrum models
-branch database: BESTIOLE
Relative rate of fissions of each isotope at time t.
ν spectrum for β decays of each isotope
Nν (Eν ,t) = Σ i ( t) . Si (Eν )
Advantage: full error propagation under control
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● Good agreement with reference spectrum● Improvement of construction method from to spectrum
The energy spectrum of neutrinos from pure 235U fission is well simulated from cumulative fission yields:
Th. Mueller, PhD Thesis
Full error and bin correlation treatment
Back up slide: Simulation results
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Simulation of detection of neutrinos for different core compositions:0.70 235U + 0.30 239Pu0.65 235U + 0.35 239Pu..................................0.50 235U + 0.50 239Pu
N 1±N 1
N 2±N 2
2=N 1−N 2
2
N 1N 2
● The red curve in case of an unchanged reactor (no change in rate)● The green curve in the case of change of 10% in core composition → extraction of 105 kg of Pu
NUCIFER at 25 m from 1GWel PWR:
with 2 relative measurements of 15 days of data before and after the reactor stop the retrieval of 80 kg of Pu can be seen with 75% C.L. and 4% probability of false alarm
Back up slide: Sensitivity to Pu content