Upload
abel-simpson
View
216
Download
0
Tags:
Embed Size (px)
Citation preview
March 19. 2009 AAP09 - Brazil - M. Fallot et
al.
Collaborations Double Chooz, Nucifer and MURE
Time evolution of reactor antineutrino energy spectrum and flux
March 19. 2009 AAP09 - Brazil - M. Fallot et
al.
Outline
2 reasons why antineutrino spectrum and flux vary with time :
- Non equilibrium : U and Pu istope and energy spectrum simulations
- Variation of the fuel isotopic content of a reactor core : reactor antineutrino spectrum and flux simulation
proliferation scenario (taking into account out of equilibrium effects when rapid power changes)
March 19. 2009 AAP09 - Brazil - M. Fallot et
al.
Integral -spectra measurements: [A. Hahn et al., Phys. Lett. B, 218,
(1989)] 235U, 239,241Pu targets @ILL, at better than 2% until 8 MeV
Summing individual -spectra: [Tengblad et al. (NPA503(1989)136)
111 nuclei @OSIRIS Studsvik and ISOLDE ]
Conversion - e : global shape uncertainty from 1.3%@3MeV to 9%@8MeV Measurement only related to thermal fission Irradiation time dependence (20 min & 1.5 d)
Don’t agree with the experimental integral spectra (important errors : 5% at 4MeV, 11% at 5MeV and 20% at 8MeV)
-spectra determinations
Remaining short-lived, high Q, unknown nuclei
March 19. 2009 AAP09 - Brazil - M. Fallot et
al.
In agreement with Chooz and Bugey data (1.9% on the e flux)
€
N (Eν , t ) ≈ α f
f
∑ (t) ⋅ρ f (Eν )- i (t) : relative contributions to the total fission (i=1) - i (E) : -spectra 235U, 239Pu, 241Pu, and 238U (Schreckenbach et al. and P. Vogel
Don’t take into account -decay from products of radiative capture of neutron
• Determination of the -spectra :
Theoretical approach : Microscopic cal. of trans. mat. elts [H-V. Klapdor, Phys. Rev. Lett., 48, (1982)] Phenomenological model for unknown nuclei + databases [P. Vogel et al., Phys. Rev. C, 24, (1981)]
• Determination of the reactor -spectra :
V. Kopeikin : Resolution of the Bateman equations for selected set of fission products + fission rates from the power plants + neutron capture contributions (ENDF database) Antineutrino experiment approaches:
-spectra determinations
March 19. 2009 AAP09 - Brazil - M. Fallot et
al.
Neutron capture, non equilibrium effects
« In the antineutrino energy range 1.8-3.5 MeV, the relative contribution of the additional radiation during the reactor operating period (Figs. 1, 5) is about 4%, which is somewhat greater than the error of the ILL spectra [5]. »
2 4
1.02
1.04
1
12
3
4
3
(,)/(,)t=0.5y t=0.5yconvers.E
Antineutrinoenergy,MeVE
E Ratio of the reactor -spectrum obtained by conversion + calculation methods to the - spectrum obtained by conversion method only convers. :1 – the additional contribution from fission product residual - activity of the previous two reactor cycles; 2 – from neutron capture by fission products; 3 – from increase of fission product - activity of the current reactor cycle from 1 day to 0.5 year; 4 – the sum (4=1+2+3)
V. Kopeikin et al. , arXiv:hep-ph/0110290
March 19. 2009 AAP09 - Brazil - M. Fallot et
al.
Addition to the spectrum : 1, 2 and 3 correspond to the beginning, middle and end of the reactor operating cycle
1.5
23
3.52.50
0,02
1
2 3Δ,1/(MeVfission)
.
F
Antineutrino energy E , MeVν
0.01
0.03
Modification of the - and spectra associated with neutron capture by fission products
Neutron capture, non equilibrium effects
But also the evolution of the and spectra during operating (ON) and shutdown (OFF) periods
Solid line is the ratio of the spent fuel pool - spectrum to the reactor spectrum. Dashed lines are the ratios of the reactor - spectrum after the reactor is shut down to the reactor - spectrum at the end of the operating cycle.
(E,toff) / (E,ton= 1 yr)
Spent Fuel Pool
0
0.02
0.04
2 32.5 3.5
toff = 1yr
toff = 1 d
V. Kopeikin et al. , arXiv:hep-ph/0110290
March 19. 2009 AAP09 - Brazil - M. Fallot et
al.
Developed simulation toolsAnd results on U and Pu isotopes
spectra
March 19. 2009 AAP09 - Brazil - M. Fallot et
al.
Principle of our strategy
weighted
Monte-Carlo Simulation :Evolution Code MURE
-branch database :BESTIOLE, …
Total e and - energy spectra with complete error treatment
- decay rates
€
Yi Z , A , t( )/e spectra
€
Sν ,i Z , A , Eν ( )
Two distinct studies
€
Nν (Eν , t ) = Yn Z , A , t( ) ⋅
n
∑ Sν ,n Z , A , Eν ( )
fissilemat. + FY
neutron flux
Core geometry nuclear
database
exp. spectrum
models
- e conversion : pas branch by branch method : no additional errorNeutron capture taken into account Long lived fission products accumulation Error treatment and propagation Nuclear database tests
March 19. 2009 AAP09 - Brazil - M. Fallot et
al.
The e spectra formulation
Coulombcorrections
Phase spaceSpectral Shape factor(Well controlled for
allowed and forbidden unique
transitions)
€
P(E0
i, E
ν ) = F(Z , E) ⋅ pE(E0
i − E)2 ⋅Sν (E)with
depends on the transition : Branching Ratios, End-
Points,spin, parity of the mother and daughter nuclei
branching ratios individual spectra
S,n (Z,A, E) = bn,i(E0) . i
i P(E0, E)
i -- -
Remaining short-lived, high Q, unknown nuclei
March 19. 2009 AAP09 - Brazil - M. Fallot et
al.
Bestiole Database
(ROOT and ASCII formats)
• Collect all available information : Nuclear Database : ENSDF
Experimental spectra 111 nuclei @ISOLDE [O. Tengblad et al., Nucl. Phys. A, 503, (1989)]
• 950 nuclei : ~ 10000 branches ~ 500 -n branches
• Tag all relevant information : Forbiddenness (spin & parity) Level of approximation
CEA/Saclay/SphN : D. Lhuillier, Th. Müller et al.
March 19. 2009 AAP09 - Brazil - M. Fallot et
al.
MURE **MCNP Utility for Reactor Evolution, O. Méplan et al. ENC Proceedings (2005) Developed by CNRS/IN2P3/IPNO and LPSC
Geometry
Evolution
•Open source code : adapted to antineutrino needs (simple geometry
implementation, easy coupling to databases …) •Benchmarked with APOLLO2 code •Fuel Burnup •Fission product distributions •Refined effects : out of equilibrium spectra • Neutron capture on FPs …
proliferation scenario calculations
Possibility to simulate :
• Simple cases : pure U or Pu isotope fissions and associated spectra• Complexe cases : reactor and associated spectra
March 19. 2009 AAP09 - Brazil - M. Fallot et
al.
Obtained spectra
X 4% agreement in the range 2 -6 MeV with Schreckenbach’s data , higher discrepancy at high energyX simulation errors (cf. Th. Müller’s talk) within the experimental error bars
Données :[A. Hahn et al., Phys. Lett. B, 218, (1989)]
Rudstam data + Bestiole + JENDL + Qb
Rudstam data + Bestiole
Ratio : (MURE - DATA)/DATA
March 19. 2009 AAP09 - Brazil - M. Fallot et
al.
Several tracks to solve these problems :
- Use of Gross Theory in existing databases such as JENDL3.3 when the considered nuclei have been treated, other models… (QRPA)
- Inclusion of existing TAGS nuclear data and new measurements
- Sensitivity to fission yields databases
Origins of the discrepancy and solutions
- ?
ZAN
Z+1AN-1
γ
γ
γ2γ1
• Pandemonium effect : use of Ge detectors to measure the decay schemes : underestimate of b branches towards high energy excited states : overestimate of the high energy part of the FP b spectra
• Unknown fission products contribute importantly at E>5-6MeV
- an alternative : the « ratio method » (see Th. Müller’s talk) : relying on the very precise Schreckenbach’s team 235U and 239Pu b spectra measurements + corrections to be applied for time evolution and neutron capture
March 19. 2009 AAP09 - Brazil - M. Fallot et
al.
decay database testing and fission yields
Treatment of Pandemonium with JENDL3.3 : Gross Theory spectra
Rudstam et al. dataJENDL totalJENDL exp. (ENSDF)BESTIOLE exp. (ENSDF)BESTIOLE beta-n branches (ENSDF)
142Cs83As 85As 89Br
Different databases for fission yields : important input for MURE simultion :
Yields from JENDL3.3
Yields from ENDFB
Yields from JEFF31
With beta spectra from :BESTIOLE + JENDL Gross Theory + Q approx.
Ratio : (MURE - DATA)/DATA
235U
[K. Takahashi and M. Yamada 1969]
-> comparer JENDL avec JEFF3 et ENDFBVII
M. Fallot et al. ND2007, L. Giot et al. Physor 2008
March 19. 2009 AAP09 - Brazil - M. Fallot et
al.
Evolution of the spectrum shape with time
235U under monoenergetic n flux (no moderation) : evolution during 1 year
To be studied in the reactor framework : under realistic n spectrum
Bin per bin comparison with respect to 0.7day -spectrumfor 60 time steps during 1 year
0 2 4 6 8 10 12
Energy (MeV)
March 19. 2009 AAP09 - Brazil - M. Fallot et
al.
World-wide initiatives
238U - spectrum integral measurement in Münschen (Niels Haag et al. @Garching ) : March-April 2009 (now !!!)
235U/239Pu ratio measurement in Moscow @Kurchatov institute (V. Kopeikin et al.)
Measurements of Pandemonium nuclei : Total Absorption Spectrometry collab. (Valence group)
D. Jordan, PhD Thesis
TAS measurements @ Univ. Jyvaskyla
Using large 4 scintillation detectors, aims to detect the full -ray cascade rather than individual -rays
12 BaF2 Crystals
New Surrey-Valencia Total Absorption Spectrometer
March 19. 2009 AAP09 - Brazil - M. Fallot et
al.
Antineutrino energy spectrum and flux reactor simulations,
« gross » proliferation scenarios
March 19. 2009 AAP09 - Brazil - M. Fallot et
al.
Scenarios and reactors of interest for IAEA ?
PWRs
BWR, FBR, CANDU reactors
Research reactor/isotope production reactors Pth >10MWth
Future reactors (PBMRs, Gen IV reactors, ADS, especially reactors using carbide, nitride, metal or molten salt fuels.
PWRs : PWR (full core) simulation and simple refuelling scenario studies
BWR, FBR, CANDU reactors : channel simulation, simplistic refuelling scenario study
Research reactor / isotope production reactors Pth >10MWth : started OSIRIS simulation for Nucifer, and high flux ILL reactor simulation
Future reactors (PBMRs, Gen IV reactors, ADS, especially reactors using carbide, nitride, metal or molten salt fuels.
An antineutrino measurement is directly related to the fission process in the reactor core.
An antineutrino measurement can provide in real time information on isotopic fission rates, which can be related to the thermal power and fissile inventory of the reactor.
International expert meeting organized by the Department of New Technologies of IAEA, October 26-28. 2008 :
March 19. 2009 AAP09 - Brazil - M. Fallot et
al.
Chooz-B reactors (I, II)
• 2 core N4 series : 4.27 GWth
• 2 core N4 series : 4.27 GWth
13 m
4,5 m
Moderator/coolant
‣ pressurized borated water (155
bars)560 K < TH2O < 620 K
(ρ= 0.7 g.cm-3 )
Moderator/coolant
‣ pressurized borated water (155
bars)560 K < TH2O < 620 K
(ρ= 0.7 g.cm-3 )
3,8 m
4,8 m
Fuel
‣enriched UO2 pellet : 1.8, 2.4 and 3.1
%
(ρ= 10.85 g.cm-3 )
700 K < TUO2 < 1400 K
Fuel
‣enriched UO2 pellet : 1.8, 2.4 and 3.1
%
(ρ= 10.85 g.cm-3 )
700 K < TUO2 < 1400 K
9 mm 13 mm
March 19. 2009 AAP09 - Brazil - M. Fallot et
al.
PWR N4 : Chooz-B (I, II)-like reactor
Fuel element
‣ 317 pellets / h = 4.2 m‣ Zircaloy coating/ 0.6 mm‣ 3 Enrichments : (1.8, 2.4, 3.1 %.)
12.6 mm
12.6 mm
‣ Zircaloy structure‣ 24 ‘guide’ tubes (poison, instrumentation,..)
214 mm
214 mm
Assembly
264
Core
‣ 3(4) enrichment zones‣ Refueling 1/3(4) 11 months
205
PWR : full core simulation. Approx. : No control rod reactor driving yet : constant power, Boron diluted into water and mean keff =1
PWR : full core simulation. Approx. : No control rod reactor driving yet : constant power, Boron diluted into water and mean keff =1
March 19. 2009 AAP09 - Brazil - M. Fallot et
al.
Neutronics inputs
Systematic effects : ✓ Temperature : Thermalisation & Doppler effect
✓ Neutron Absorbant : Bore
Systematic effects : ✓ Temperature : Thermalisation & Doppler effect
✓ Neutron Absorbant : Bore
• A matter of neutronics : neutron flux & interaction cross sections (n,x)
• A matter of neutronics : neutron flux & interaction cross sections (n,x)
Fast neutronsFission spectrum
~2MeV
Fast neutronsFission spectrum
~2MeVSlow
neutronsthermalisation
~0.025eV
Slow neutrons
thermalisation ~0.025eV
Epithermal domain
+moderator 1eV<En<1MeV
Epithermal domain
+moderator 1eV<En<1MeV
‣ Φ ~ 3,5 .10 14 n.cm-2.s-1 | <En> ~ 0.7 MeV‣ Φ ~ 3,5 .10 14 n.cm-2.s-1 | <En> ~ 0.7 MeV
Burnup effect
Burnup effect
σ(n,f) 238U
σ(n,γ) 238U
σ(n,f) 235U
σ(n,γ) 235U
March 19. 2009 AAP09 - Brazil - M. Fallot et
al.
‣Thermal bump displacement :
Systematic effects • Thermalization :• Thermalization : • Doppler effect :• Doppler effect :
0 K
1800 K
• Boron Cross sections 1/v• Boron Cross sections 1/v
‣ Harder neutron spectrum
Tfuel ➚ ⇒ Resonant captures➚
• Criticity control with soluble boron :
‣ Cbore adjusted at each time step t , <keff (t+1) >= 1
• Criticity control with soluble boron :
‣ Cbore adjusted at each time step t , <keff (t+1) >= 1
March 19. 2009 AAP09 - Brazil - M. Fallot et
al.
Systematic effects
Guessed uncertainties on input parameters
Inventory : ΔN (%) Nfission : Δ(Nf/s) (%)
235U 238U 239Pu 241Pu 235U 238U 239Pu 241Pu
ΔTm = 30 K 0.5 < 0.1 1. 0.8 0.4 < 0.1 < 0.1 1.5
ΔTf = 200 K 1. < 0.1 2. 2.5 1. 0.5 0.8 1.
ΔcB = 200 ppm 0.7 < 0.1 2. 1.8 2.4 2. 0.5 0.8
Δ(mean keff=1 or keff=1)
0.2 4.4 0.8 2.2
• Systematic study : ‣ T moderator : 300, 600,... 1200K‣ T fuel : 300, 600,.... 1500 K‣ Boron Concentration : 0, 500,... 3000 ppm mass.
• Systematic study : ‣ T moderator : 300, 600,... 1200K‣ T fuel : 300, 600,.... 1500 K‣ Boron Concentration : 0, 500,... 3000 ppm mass.
n, En, keff(<>, Inventory, Nf/s.
n, En, keff(<>, Inventory, Nf/s.
Also studied : - self-shielding effect on inventories and fission rates, - influence of the Monte-Carlo seed
Studied effects : of the order of 2% or
lower on main fission rates (exc. 238U)
March 19. 2009 AAP09 - Brazil - M. Fallot et
al.
PWR refueling simulation
Constant power : 4.27GWth
Boron concentration 1000ppmMean keff = 1
PWR refuelled every year :250kg 239Pu retrieval900kg 235U adjunction
Constant power simulation of N4 PWR
6.4%
Folded by Nucifer response @25m :
Preliminary
Antineutrino rate/s in Nucifer
March 19. 2009 AAP09 - Brazil - M. Fallot et
al.
Filling all control rods with 238U
25*205 control rods :
+11.5t 238U=> 238U mass
increase of 10%
Folded by Nucifer response @ 25m :
235U : +150kg239Pu :+100kg
235U and 239Pu fission rates change by -5.5% and +2.5% resp.
Antineutrino flux :Change of 0.5% !
Because of 238U fission rate increase +6-8% :
mimick 235U
238U inventory
235U and 238Pu inventory
Fission rates
Antineutrino rate/s in NuciferPreliminary
PreliminaryPreliminary
Preliminary
March 19. 2009 AAP09 - Brazil - M. Fallot et
al.
Removal of the control rods
Corresponds to 65kg 239Pu removal, without changing 238U and 235U masses as rods are replaced by fresh Unat
Amount of 238U stays ~ the same, so no compensation by 238U of 235U and 239Pu fission
rates variations
Preliminary
1.3%
Normal refuelling
Replacement of the control rods
March 19. 2009 AAP09 - Brazil - M. Fallot et
al.
CANDU reactor specifications(CANada Deuterium Uranium)
http://canteach.candu.org
Heavy water as moderator and coolant and natural uranium as fuel
Spatial separation of coolant (in force tubes) and moderator (between force tubes)
On-line refuelling :
Plutonium proliferation
Antineutrino flux and spectra : refuelling and 239Pu proliferation scenarii
Calandria
moderator
Force tubesV.M. Bui PhD, Collaboration with A. Nuttin (LPSC)
(*)A. Nuttin, Physor-2006, Study of CANDU Thorium-based Fuel Cycles by Deterministic and Monte Carlo Methods.
March 19. 2009 AAP09 - Brazil - M. Fallot et
al.
Simulation inputs
A channelA bundle
Fresh fuel
1 32 Pool
4 5 1’
Irradiated fuel
Moderator
Mirror
Annular gas CO2
coolant
Calandria tube
37pins
Force tube
Refuelling of a channel 2/3 fresh fuel and 1/3 irradiated fuel
Different simulation steps :
Force tube →channel of 12 fuel bundles
1 bundle + mirror → full reactor, homogeneous, infinite (no leak)
Fit boundary mirror dimensions to obtain the CANDU moderation ratio
Temperature dependance : Tmod= 300 K Tcool= 600 K Tfuel= 1200 K
Spatial dependance of the neutron flux
Dwell time def. : threshold 1.05 (A. Nuttin* et al.) : leaks : 3000pcm, absorptions (Boron and impurities) : 2000pcm.
T= 300 K for all components
)(
)1(
tN
tNK
neutrons
neutrons +=∞
Correct mean temperatures
Dwell time : 200d
March 19. 2009 AAP09 - Brazil - M. Fallot et
al.
Channel simulation & gross diversion scenario
3 channels (12 bundles) simulations with 100d, 200d and 300d refueling periods
Principle : refuel faster some channels to take Pu away and refuel slower the same number to mask diversion
Isotopic Vector Plutonium: Pu of military quality (VP>90%)
2 “full core” refuelling scenarii
- Standard : 400 channels refueled @200 days
- Proliferant : 200 channels refueled @ 100d + 200 channels refueled @ 300d to mask diversion
X-checks : collaboration with A. Nuttin et al., Physor 2006 Conf. Proc. , comparison between MURE and deterministic code DRAGON
Inventory @ refuelling period 100d
Inventory @ refuelling period 200d
Inventory @ refuelling period 300d
March 19. 2009 AAP09 - Brazil - M. Fallot et
al.
A gross proliferation scenario e
in N
ucife
r (H
z)F
its a
nd s
ums
Folded with Nucifer response @ 25m for 1 channel with different refueling periods :
100d 200d 300d
0 100 200 300 4000 100 200 300
Time (days)
0 100 200 300 400
Time (days)Time (days)
400 channels (~ CANDU600-like) refueled every 200d, @ 2 channels per day : adequation between dwell time, daily number of refuelled channels and total number of channels : flat profile of the flux
« Normal refueling » :
+…+
Adding 400 channels with history shifted by 1 day
0 100 200 300 400
0.02588 Hz => 2236 per day in Nucifer
Preliminary
Time (days)
March 19. 2009 AAP09 - Brazil - M. Fallot et
al.
Core refuelled @ 100d and 300d
Folded by Nucifer response @ 25m :
200 channels refuelled every 100d, 200 channels every 300d, @ 2 channels per day
3.5% discrepancy in the antineutrino rate !!!Nucifer reaches 1% statistic precision after 1 day
3.5% discrepancy in the antineutrino rate !!!Nucifer reaches 1% statistic precision after 1 day
Fission rates : Normal refuelling : 54.1% 235U - 45.9% 239PuDiversion scenario : 60,1% 235U - 39,9% 239Pu
Time (days)
0 100 200 300 400
+660kg 235U after 200x100d + 200x300d-430kg 239Pu including 152kg from 100d channels
0.02497 Hz => 2157 per day
0 100 200 300 400
Time (days)
0.02588 Hz => 2236 per day
+600kg 235U after 400x200d-464kg 239Pu
March 19. 2009 AAP09 - Brazil - M. Fallot et
al.
Conclusions and outlooks
A set of performant tools (MURE+BESTIOLE+databases…) to compute the antineutrino energy spectrum and flux under various conditions : experiment and reactor simulations
Neutron capture and long-lived fission products contributions to the spectrum : need to be evaluated carefully and compared with Kopeikin’s et al. results
Simulation of different kinds of reactors, including Chooz-B ones for the Double Chooz experiment
First gross proliferation scenarios studied, with PWR and CANDU reactors, including the response of the Nucifer detector placed at 25m from the cores
Nucifer sensitivity in 239Pu content : ~+-65kg <=> 1% change in the measured antineutrino flux by Nucifer @25m of a PWR core,
1% statistical accuracy reached in 4days by Nucifer in these conditions
March 19. 2009 AAP09 - Brazil - M. Fallot et
al.
Backup Slides