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BgNS International Conference September 18-21, 2013, Sunny Beach, Bulgaria
Reactor Dosimetry in NPP Lifetime Reactor Dosimetry in NPP Lifetime Management and Decommissioning Management and Decommissioning
Tasks Tasks
Sergey Belousov Krassimira Ilieva
Desislava Kirilova*Mladen Mitev
Institute for Nuclear Research and Nuclear Energy of Bulgarian Academy of Science
*Kozloduy NPP
BgNS International Conference September 18-21, 2013, Sunny Beach, Bulgaria
OUTLINE
IntroductionREACTOR DOSIMETRY TasksUnits in Operation
REACTOR DOSIMETRY and PTSALifetime Extension
REACTOR DOSIMETRYin Decommissioning
General Conclusion
BgNS International Conference September 18-21, 2013, Sunny Beach, Bulgaria
Introduction (1)Introduction (1)
• There are six power units at Kozloduy Nuclear Power Plant (KNPP) in Bulgaria. Two of them (VVER 1000/320 type) are in operation now when other four (VVER 440/230 type) are shut down. For the Units 5 and 6 that are in operation the lifetime extension task is one of the most important. For the Units 1 to 4 that are shut down the task of radiological characterization for decommissioning purposes is of crucial interest.
BgNS International Conference September 18-21, 2013, Sunny Beach, Bulgaria
Introduction (2)Introduction (2)
• More then thirty years, since 1989 the Institute for Nuclear Research and Nuclear Energy of Bulgarian Academy of and Sciences (INRNE) has provided for KNPP a scientific assistance in the field of rector dosimetry which is a tool for nondestructive assessment of reactor pressure vessel (RPV) metal embrittlement.
BgNS International Conference September 18-21, 2013, Sunny Beach, Bulgaria
Introduction (3)Introduction (3)
• The data for the neutron fluence accumulated on the RPVs of all units during the operated cycles was assessed by calculation and verified by ex-vessel activation detectors. Assessment of the neutron fluence on the so called surveillance samples-witness has been done according to the Surveillance program of Units 5 and 6.
BgNS International Conference September 18-21, 2013, Sunny Beach, Bulgaria
Reactor Dosimetry TasksReactor Dosimetry TasksUnits in OperationUnits in Operation
BgNS International Conference September 18-21, 2013, Sunny Beach, Bulgaria
Reactor Pressure Vessel (RPV)Reactor Pressure Vessel (RPV)Current state
Neutron Embrittlement
TF = AF F1/3
Rest Lifetime
Rest cycles
LT = (Fmax -F)/Favr
Fmax ← Tka ← PTSPTS
Reduction of neutron fluence
Operation management
low leakage schemedummy cassettesweld axial level
Surveilance locationsSurveilance locationsSurveilance Program
witness-samples (surveillances) treatmentwitness-samples (surveillances) treatment
BgNS International Conference September 18-21, 2013, Sunny Beach, Bulgaria
NEUTRON FLUENCE ASSASSMENT (LiM)NEUTRON FLUENCE ASSASSMENT (LiM)
XS LibrariesBGL 440, 1000
Body Model(R,,Z)-meshes
Power andBurnup
Distribution
Material XSDATA
(TORT)
Loading / OperationalHistory DATA
Geometry & MaterialDATA
(R,,Z)-source(TORT)
Decay DPA’ XS Const Det’ XS
RESULTSFluence, Activity,
Damages
RC SimulationCode
DOSRC
GIP
TORT
VISDO
MCNP XS DATA
MCNP
Measured Activities,Uncertainty,Correlation
Least Squares Adjustment
“Best estimatedFluence”
Task parameters (XS,Densities, Dimensions),Uncertainty, Correlation,
Sensitivity
Decay DPA’ XS Const Det’ XS
BgNS International Conference September 18-21, 2013, Sunny Beach, Bulgaria
NEUTRON FLUENCE AND DETECTORS’ NEUTRON FLUENCE AND DETECTORS’ ACTIVITY CALCULATIONACTIVITY CALCULATION
TORT deterministic discrete ordinate codes BGL multigroup library
for VVER-1000 and VVER-440 BUGLE96 multigroup library for PWR
MCNP Monte Carlo code MCNPDATA library with continuous
neutron cross section energy dependence
DOSRC, VISDO code for fixed sourcesgenerating and geometry model visualization
BgNS International Conference September 18-21, 2013, Sunny Beach, Bulgaria
R1
R2
1
2
body
DOSRC, VISDO - sources generating and geometry visualization
NEUTRON FLUENCE AND DETECTORS’ NEUTRON FLUENCE AND DETECTORS’ ACTIVITY CALCULATIONACTIVITY CALCULATION
BgNS International Conference September 18-21, 2013, Sunny Beach, Bulgaria
Sources of Calculation Uncertainties:
• plant independent parameters: nuclear data
• plant dependent parameters: constructional data geometry dimensions, densities and materials’ content
operational data neutron source etc.
• approximations of calculation methods
BgNS International Conference September 18-21, 2013, Sunny Beach, Bulgaria
Calculation uncertaintiesCalculation uncertainties
Source of uncertaintyFluence,
%Cu detector,
%Fe detector,
%Nb
detector, %
Iron XS inelastic 8.3(4.9*) 35.(14.*) 31.(16.*) 13.(8.3*)
Iron XS elastic 8.9 8.5 12. 14.
Iron XS absorption 2.3 9.7 5.7 3.1
Chromium XS inelastic 4.9 6.4 6.5 5.5
Chromium XS elastic 1.5 0.84 1.3 1.7
Chromium XS absorption 0.12 0.43 0.27 0.15
Hydrogen XS elastic 2.5 1.4 1.9 2.4
Oxygen XS elastic 2.8 1.8 2.4 2.8
Source spectrum 4.8 12. 7.7 5.3
Source spatial distribution 3.9 3.3 3.6 3.8
Steel density 2.5 3.7 3.8 3.2
Moderator density 5.4 3.7 4.3 5.2
RPV inner radius 7.4 4.2 3.7 0.35
Total 18.(12.*) 41.(20.*) 36.(19.*) 23.(12.*)
BgNS International Conference September 18-21, 2013, Sunny Beach, Bulgaria
BEST ESTIMATED FLUENCEBEST ESTIMATED FLUENCE
after 1D adjustment VVER-1000
9.7-12.6.6-15.4.4-5.24.5-5.5
STD, %δ STD, %δ , %STD, %δ , %STD, %δ , %
FluenceNb detectorFe detectorCu detector
r̂ r̂ r̂ F̂
Tasks for further improvement:
• Sensitivity matrices in maximum irradiated positions• XS uncertainty correlation matrices• XS data improvement
BgNS International Conference September 18-21, 2013, Sunny Beach, Bulgaria
Methodology ValidationMethodology Validation ((NPP)
V V ER 1 00 0
R E A C TO R C OR E
R E A C T OR VE S S E L
C A VIT Y
29
07
W E L D 3
W E L D 2
22
43
15
00
13001300
S U P P OR T R A C K S
S U P P OR T S Y S TE M
N b D ET E C TO R S
Fe , C u D E TE C TO R S
DEVICE FOR IRRADIATION OF DETECTORS IN THE AIR CAVITY BEHIND THE VVER-1000 RPV
Unit 5, cycles 6
a,kBq/g 54Fe(n.p)54Mn
calc exp
8
12
16
20
140 160 180 200
a,kBq/g 63Cu(n,)60Co
calc exp
0.2
0.4
05
0.6
0.3
140 160 180 200
BgNS International Conference September 18-21, 2013, Sunny Beach, Bulgaria
MethodologyMethodology Validation Validation ((NPP surveilance)NPP surveilance)
Location of surveillance assemblyin VVER-1000/320
2
4
6
8
10
12
14
16
18
20
22
24
26
2L1
Ne
utr
on
Flu
en
ce, 1
018 c
m-2
2L2 2L3
Lower, cal.
Lower, exp.
Upper, cal.
Upper, exp.
2L4 2L5
BgNS International Conference September 18-21, 2013, Sunny Beach, Bulgaria
VVER-1000 Mock-up
Methodology Verification (Methodology Verification (BenchmarkBenchmark)) LR0 in Rez, Czech Republic
VVER-440 Mock-up dummy
VVER-440 Mock-up standard
Conformity Mock-up – NPP UnitAttenuation and Spectra
0 5 10 15 20 25 30
Azimuth, deg
-25
-20
-15
-10
-5
0
5
10
15
20
25
(AF
/AF
m-1
),%
VVER440 standardVVER440 dummy VVER1000
BgNS International Conference September 18-21, 2013, Sunny Beach, Bulgaria
RD CollaborationRD Collaboration
The neutron fluence evaluation methodology is being developed under research projects USA NRC, IAEA and EC in close collaboration of Russia, Czech Republic, Germany, Spain, Bulgaria, Belgium, Hungary and Ukraine, and especially within the activity of the European Working Group on Reactor Dosimetry (EWGRD) and WGRD-VVER group of the countries operating VVER. The WGRD-VVER group was created in 1990. The EWGRD activity is dated from 1994.
BgNS International Conference September 18-21, 2013, Sunny Beach, Bulgaria
ConclusionsConclusions
The RD methodology developed in the Institute for Nuclear Research and Nuclear Energy of Bulgarian Academy of Science is at the state of the art at the state of the art levellevel
The state of the art RD provides reliable assessment results (with uncertainty less than 10%) for neutrons with energy above .1 MeV
Further efforts are needed to achieve the same level of accuracy for thermal neutrons and gammas
BgNS International Conference September 18-21, 2013, Sunny Beach, Bulgaria
Reactor DosimetryReactor Dosimetry and PTS Analysis and PTS Analysisin in Lifetime ExtensionLifetime Extension
BgNS International Conference September 18-21, 2013, Sunny Beach, Bulgaria
IAEA-EBP-WWER-08 (Rev. 1)
BgNS International Conference September 18-21, 2013, Sunny Beach, Bulgaria
KKII ≤ [K ≤ [KICIC]][K[KICIC] - ] - allowable stress intensity factorallowable stress intensity factor
KKII - - crack loading in terms of stress intensity factor crack loading in terms of stress intensity factorTTkk
aa - RPV maximum allowable critical brittle fracture - RPV maximum allowable critical brittle fracture
temperaturetemperature
BgNS International Conference September 18-21, 2013, Sunny Beach, Bulgaria
Critical temperature of brittlenessCritical temperature of brittleness TTKK
TTKK = T = TK0K0 + + ΔΔTTFF + + ΔΔTTTT + + ΔΔTTNN
ΔTΔTFF = = AAFF . (F.10. (F.10-22-22))nn
Master Curve (MC) approach (VERLIFE)Master Curve (MC) approach (VERLIFE)
[K[KICIC] = 25.2 + 36.6 · exp ] = 25.2 + 36.6 · exp 0.019 ( 0.019 (ΔΔTT)) ΔΔT = T = RTRT00 = T = T00 + + ; Reference temperature T; Reference temperature T00
PNAE G-7-002-86 doc – accidental situationPNAE G-7-002-86 doc – accidental situation
[K[KICIC] = 26 + 36 · exp ] = 26 + 36 · exp 0.02 ( 0.02 (ΔΔTT)),, ΔΔTT = T – T = T – Tkk
base metalbase metal
[K[KICIC] = 74 + 11 · exp ] = 74 + 11 · exp 0.0385 ( 0.0385 (ΔΔTT ) ) , , ΔΔTT = T – T = T – Tkk
weld metalweld metal[K[KICIC] = 35 + 53 · exp ] = 35 + 53 · exp 0.0217 ( 0.0217 (ΔΔTT ) ) , , ΔΔTT = T – T = T – Tkk
[Kic]
0.00
100.00
200.00
300.00
400.00
500.00
600.00
700.00
-150 -100 -50 0 50 100 150
ΔT, ºC
VERLIFE
PNAE G
PNAE B
PNAE W
BgNS International Conference September 18-21, 2013, Sunny Beach, Bulgaria
IAEA-EBP-WWER-08 (Rev. 1)
MATERIAL SCIENCE
REACTOR DOSIMETRY
STRUCTURAL ANALYSIS
THERMAL HYDRAULICS
Fields of studyFields of study(ALPHABETIC ARRANGEMENT)(ALPHABETIC ARRANGEMENT)
BgNS International Conference September 18-21, 2013, Sunny Beach, Bulgaria
Developing the team approach …
from N. Taylor presentation at JRC WS 11-13.10.2006
BgNS International Conference September 18-21, 2013, Sunny Beach, Bulgaria
Application of FFP approach requires clear description of the uncertainties of the results of all disciplines uncertainties of the results of all disciplines involvedinvolved. Uncertainty decreasing is a way for increasing of the limit values without reduction of conservatism.
Another useful approach consists in application of local Tk
a distribution over RPV. The local assessmentlocal assessment could let us to increase the fluence limit value taking into account that the positions of the highest fluence does not coincide with positions where stress intensity factor KI reaches its highest values during PTS accident.
ConclusionsConclusions
BgNS International Conference September 18-21, 2013, Sunny Beach, Bulgaria
Reactor Dosimetry in Reactor Dosimetry in Decommissioning TaskDecommissioning Task
BgNS International Conference September 18-21, 2013, Sunny Beach, Bulgaria
Available DocumentsAvailable Documents• [1] “Nuclear Data Requirements for Fission
Reactor Decommissioning,” IAEA INDC(NDS)-269, January 1993
• [2] “Decontamination and decommissioning of nuclear facilities,” IAEA-TECDOC-716, August 1993
• [3] “Radiological Characterization of Shut Down Reactors for Decommissioning Purposes,” IAEA Technical Reports Series No. 389, October 1998
BgNS International Conference September 18-21, 2013, Sunny Beach, Bulgaria
CONTRIBUTORS TO DRAFTING AND REVIEWAnttila, M. VTT Energy, FinlandCrégut, A. Consultant, FranceCross, M.T. AEA Technology, United KingdomDlouhy, Z. Radioactive Waste Management and
Environmental Protection Consulting Services, Czech Republic
Elkert, J. ABB Atom AB, SwedenFedorowicz, R. Atomic Energy of Canada Ltd, CanadaGenova, M. Centro Informazioni Studi Esperienze, ItalyImbard, G. Commissariat à l’énergie atomique, FranceKlein, M. Centre d’étude de l’énergie
ucleaire/Studiecentrumvoor Kernenergie (CEN-SCK), Belgium
Laraia, M. International Atomic Energy AgencyLe Goaller, C. Commissariat à l’énergie atomique, FranceMadrid, F. Empresa Nacional de Residuos Radioactivos, SpainReisenweaver, D.W. Nuclear Energy Services, United States of
AmericaSancho Llerandi, C. Centro de Investigaciones Energéticas,
Medioambientales y Tecnológicas, SpainShidlovskii, V.V. Mayak Production Association, Russian
FederationSivintsev, Y. Russian Research Centre “Kurchatov Institute”,
Russian FederationSmith, R.I. Consultant, United States of AmericaValencia, L. Kernforschungszentrum Karlsruhe, Germany
Consultants MeetingsVienna, Austria: 6–10 March 1995; 18–22 November 1996
Advisory Group MeetingVienna, Austria: 12–16 February 1996
BgNS International Conference September 18-21, 2013, Sunny Beach, Bulgaria
TABLE II. THE MOST IMPORTANT ACTIVATION REACTIONS CONSIDERED [3]
BgNS International Conference September 18-21, 2013, Sunny Beach, Bulgaria
TABLE II. THE MOST IMPORTANT ACTIVATION REACTIONS CONSIDERED [3](continued)
BgNS International Conference September 18-21, 2013, Sunny Beach, Bulgaria
TABLE VII. RADIOACTIVE INVENTORY OF A TYPICALWWER 440 (GREIFSWALD UNIT 1) FOR MAJOR COMPONENTS [3]
BgNS International Conference September 18-21, 2013, Sunny Beach, Bulgaria
TABLE XII. RADIOACTIVE INVENTORY OF TRINO PWR(ITALY) [3]
BgNS International Conference September 18-21, 2013, Sunny Beach, Bulgaria
RELATIVE IMPORTANCE OF RADIONUCLIDES WITH TIME [3]
The principal activation products present in reactor materials at shutdown are 55Fe, 60Co, 59Ni, 63Ni, 39Ar, 94Nb (in steels); 3H, 14C, 41Ca, 55Fe, 60Co, 152Eu, 154Eu (in reinforced concretes) and 3H, 14C, 152Eu and 154Eu (in graphites). In terms of radiation levels, 60Co is the most predominant radionuclide. For steels, 55Fe and 60Co account for the major part of the inventory in the first ten years after shutdown. In the following 50 years, most of this activity has decayed, leaving the longer lived nickel, niobium and silver isotopes to dominate. For graphites and concretes, the short term decay is dominated by 3H, leaving the longer lived 14C, 41Ca and Eu isotopes to dominate in the longer term. After decay periods of more than 100 years, sufficient gamma activity from trace rare earth elements (e.g. Eu) is present to warrant the adoption of semiremote dismantling methods for reactor bioshields.
BgNS International Conference September 18-21, 2013, Sunny Beach, Bulgaria
RELATIVE IMPORTANCE OF RADIONUCLIDES WITH TIME [3]
BgNS International Conference September 18-21, 2013, Sunny Beach, Bulgaria
RELATIVE IMPORTANCE OF RADIONUCLIDES WITH TIME VVER 500 Armenian NPP - calculated
BgNS International Conference September 18-21, 2013, Sunny Beach, Bulgaria
PARAMETERS INFLUENCING THE RADIONUCLIDE INVENTORYPARAMETERS INFLUENCING THE RADIONUCLIDE INVENTORY
For all reactor types, the radionuclide composition of activated and contaminated materials may vary within a very wide range. The most important factors and parameters are:
•the neutron fluence, •the duration of the operation,•the time elapsed after reactor shutdown.• Reactor type, design, power level and shutdown period;• Composition of construction materials, including trace
elements;• Operational parameters, e.g. chemistry of the heat transfer
medium, and maintenance;• Unplanned events.
BgNS International Conference September 18-21, 2013, Sunny Beach, Bulgaria
NEUTRON ACTIVATION ASSESSMENT (DT)NEUTRON ACTIVATION ASSESSMENT (DT)Updated INRNE MethodologyUpdated INRNE Methodology
XS LibrariesBGL 440, 1000
Body Model(R,,Z)-meshes
Power andBurnup
Distribution
Material XSDATA
(TORT)
Loading / OperationalHistory DATA
Geometry & MaterialDATA
(R,,Z)-source(TORT)
Decay ConstActivation XS
RESULTSActivity, Spectra
RC SimulationCode
DOSRC
GIP
TORT
VISDO
MCNP XS DATA
MCNP
ORIGEN
Decay ConstActivation XS
RESULTSInventiory, Activity, Doses*
EASY 2010
BgNS International Conference September 18-21, 2013, Sunny Beach, Bulgaria
Tasks for further improvement:
• XS libraries generation appropriate for thermal neutrons energy range
• Methodology benchmarking (based on JPDR data [1]) for methodology verification/validation
• International collaboration improvement• FFP approach implementation
In comparison with discussed in [3] is updated by
• 3D transport codes application• EASY code implementation (appropriate ORIGEN
alternative )
NEUTRON ACTIVATION ASSESSMENT (DT)NEUTRON ACTIVATION ASSESSMENT (DT)
Microsoft PowerPoint Presentation
BgNS International Conference September 18-21, 2013, Sunny Beach, Bulgaria
The RD methodology developed in the Institute for Nuclear Research and Nuclear Energy of Bulgarian Academy of Science for Surveillance Program at NPP is at the state of the art levelthe state of the art level
This methodology could be modified for the decommissioningdecommissioning purposes
Tasks for the furtherfurther methodology improvementimprovement are determined
Application of FFP approachFFP approach should be very useful for NPP problems management
General ConclusionsGeneral Conclusions