SEMINARIUM GEOFIZYKI WIERTNICZEJ WELL LOGGING SEMINAR

Transcription

1 SEMINARIUM GEOFIZYKI WIERTNICZEJ WELL LOGGING SEMINAR, Naukowa Sieć Tematyczna Metody Jądrowe dla Geofizyki IFJ PAN INiG ING PAN

2 Możliwo liwości symulacyjnych technik Monte Carlo na przykładach adach sondy NNTE i spng Possibilities of computer simulations techniques using Monte Carlo codes on examples of the NNTE and spng tools Teresa Cywicka-Jakiel, Andrzej Drabina, Urszula Woźnicka nicka

3 Experience and achievement of the Institute of Nuclear Physics in nuclear geophysics

4 In 1970 Professor Jan A. Czubek establish Department of Nuclear Physics Applications NUCLEAR GEOPHYSICS Analytical solutions of particle transport (gamma, neutron) Pulsed neutron generaor 14 MeV Numerical codes for particle transport Semi-empirical calibration method for neutron tools Sigma-a laboratory measurement method FLUKA, MORSE MCNP

5 Present status Department of Environmental and Radiation Transport Physics (NZ54) Head: : Prof. Dr.. hab. Urszula Woźnicka Neutron Transport Physics Laboratory Head: Assoc.. Prof. Krzysztof Drozdowicz Natural Radioactivity Laboratory Head: Dr.. Krzysztof Kozak

6 Neutron Transport Physics Laboratory organisation Nuclear Well Logging Research & Development Centre (cooperation with AGH, Geophysics Dept.) budget Scientific Network: : Nuclear Methods for Geophysics IFJ PAN Oil and Gas Institute Institute of Geological Sciences PAN

7 Monte Carlo simulations of well logging problems Type of numerical codes (FLUKA, MCNP) and nuclear libraries (ENDF, Abagian) Modeling of the Zielona Góra Facilities Modeling of the the spectrometric neutron-gamma well logging probe, SO SN Modeling of the neutron-neutron tool NNTE Monte Carlo contra semi-empirical empirical calibration NNTE response in the multi-layer system

8 Monte Carlo numerical codes and nuclear libraries A fully integrated particle physics Monte Carlo simulation package. FLUKA has many applications in high energy experimental physics and engineering, shielding, detector and telescope design, cosmic ray studies, dosimetry, medical physics and radio-biology. MCNP - A General Monte Carlo N-Particle Transport Code MCNP is a trademark of Los Alamos National Security, LLC Los Alamos National Laboratory.

9 MCNPX is a general-purpose Monte Carlo radiation transport code for modeling the interaction of radiation with everything. MCNPX stands for Monte Carlo N-Particle extended. It extends the capabilities of MCNP4C3 to nearly all particle types, to nearly all energies, and to nearly all applications without additional computational time penalty. MCNPX is fully three-dimensional and time dependent. It utilizes the latest nuclear cross section libraries and uses physics models for particle types and energies where tabular data are not available. Applications range from outer space (the discovery of water on Mars) to deep underground (where radiation is used to search for oil) MCNPX is used for nuclear medicine, nuclear safeguards, accelerator applications, nuclear criticality, and much more.

10 Monte Carlo numerical codes and nuclear libraries Nuclear libraries Evaluated Nuclear Data Files (ENDFxx) Possible differences in the results: The same libraries BUT different method of use

11 Nuclear libraries Evaluated Nuclear Data Files (ENDFxx) Total neutron cross section [barn] H 0 1 E-07 1 E-06 1 E-05 1 E-04 1 E-03 1 E-02 1 E-01 1 E+00 1 E+01 1 E+02 Energy [MeV]

12 x x x ENDF data x Calculated ( continuous ) data (MCNP) x x Group data (FLUKA) E-01

13 Modeling of the material and geometry of the Zielona Góra Facilities Nuclear tool NNTE loggingl water Water block Standard block concrete Concrete

14 Modeling of the material and geometry of the Zielona Góra Facilities Nuclear tool (NNTE) KW Water L13 Ceramic block

15 Modeling of the the spectrometric neutronn eutron-gamma well logging probe, SO SN Water pool Rock model n-gamma probe (SO-5-90-SN type) Detector (BGO) Aluminium Steel Lead Am-Be soure BGO detector Hole Am-Be source Concrete base

16 Modelling of the the spng (SO-5-90-SN) Problems: 1. Benchmark calculations: comparison of the tool responses obtained in realistic and simulated measurements at the Zielona Góra Facility 2. Calibration of the SO SN tool: calculation of the tool respons in media inaccessible at Zielona Góra 3. Influence of side effects: presence of chlorine in borehole/rock

17 Modeling of the the spng Benchmarks (SO-5-90-SN) I-H-pom [imp/s] SO-5-90-SN Pi Jo2 950 Mo2 BM2 Ra2 Li2 Mu2 Ze2 Br2 R 2 = I-H-MCNP [imp/s] 95% p.uf ności I-Si-pom [imp/s] SO-5-90-SN Pi2 Li2 Jo2 Ze2 BM2 Mo2 Ra2 Br2 Mu I-Si-MCNP [imp/s] R 2 = % p.uf ności I-Ca-pom [imp/s] SO-5-90-SN Mu2 Li2 Br2 Ra2 Pi2 Ze2 BM2 Mo2 Jo2 R 2 = % p.uf ności I-Fe-pom [imp/s] SO-5-90-SN Li2 Jo2 Pi2 BM2 Mo2 Ra2 Ze2 Mu2 Br2 R 2 = % p.uf ności I-Ca-MCNP [imp/s] I-Fe-MCNP [imp/s]

18 Modeling of the the spng Benchmarks (SO-5-90-SN) Reasons: 1. The elemental composition of rock standards should be known in more detail

19 Modeling of the the spng (SO-5-90-SN) Benchmarks: elemental composition Mean concentrations of some important thermal neutron absorbents in the Zielona Góra blocks (laboratory measured,, 2005) Wzorzec skalny B (ppm) Cl (ppm) Gd (ppm) Sm (ppm) Eu (ppm) nazwa Mucharz , Brenna Radków n.o (*) Żerkowice ~ ~ Libiąż n.o (*) n.o. (*) n.o. (*) Morawica n.o (*) Pińczów n.o (*) Józefów n.o (*) Biała Marianna n.o (*)

20 Modeling of the the spng (SO SO SN SN) Benchmarks: elemental composition Mucharz2 - simutation MCNP and measurement VII TM2_2d1 - Mu2_GEB 0,187 XRAL - TMu2_4_GEB 0,187 Mu2 - BGW VII H (2,01-2,521) MeV Si (2,625-5,228) MeV Ca (5,332-6,789) MeV Fe (6,893-8,975) MeV Gamma energy (MeV) Counts rate (imp/s) Ca: 3,610 MeV Ca: 4,419 Ca:6,42 MeV Fe: 7,64 MeV; Al: 7,72 MeV Fe: 9,2981st esc MeV Si: 1,78 MeV H: 2,223 MeV Si: 3,539 MeV Si: 4,934 MeV

21 Modeling of the the spng Benchmarks (SO-5-90-SN) Reasons: 1. The elemental composition of rock standards should be known in more detail 2. ENDF libraries

22 Cl(n,γ)Cl - gamma ray lines Cl(n,γ)Cl - gamma ray lines endf Eγ (MeV) Iγ (per 100 captures) Iγ (per 100 captures) Modeling of the the spng (SO SO SN SN) Benchmarks: ENDF libraries ACTIA Eγ (MeV)

23 Modeling of the the spng (SO-5-90-SN) Benchmarks: ENDF libraries Al(n,γ )Al gam m a-ray lines Iγ (per 100 captures) M ev (delayed) ACTIA E γ (MeV)

24 Modeling of the the spng (SO-5-90-SN) Benchmarks: improvement I Si meas (cps) Measurement vs. MCNP simulations (ENDF/BVI.2 neutron library) Si(n,γ)Si Eγ = 3.54 and 4.93 MeV R 2 =.7598 I Si meas (cps) I Si MCNP (cps) Measurement vs. MCNP simulations (ENDF/BVI.8 neutron library) Si(n,γ)Si Eγ = 3.54 and 4.93 MeV R 2 = % conf I Si MCNP (cps) 95% conf.

25 I H meas (cps) Measurement vs. MCNP simulations (ENDF/BVI.2 neutron library) H(n,γ)H Modeling of the the spng (SO-5-90-SN) Benchmarks: improvement Eγ = 2.22 MeV R 2 =.7977 I H meas (cps) Measurement vs. MCNP simulations (ENDF/BVI.8 neutron library) H(n,γ)H Eγ = 2.22 MeV R 2 = % conf I H MCNP (cps) I H MCNP (cps) 95% conf.

26 Modeling of the the spng (SO-5-90-SN) Benchmarks: improvement I Fe meas (cps) Measurement vs. MCNP simulations (ENDF/BVI.2 neutron library) Measurement vs. MCNP simulations Fe(n,γ)Fe (ENDF/BVI.8 neutron library) Eγ = 7.63 and 7.64 MeV 120 R 2 =.6515 I Fe meas (cps) % conf I Fe MCNP (cps) Fe(n,γ)Fe Eγ = 7.63 and 7.64 MeV R 2 = I Fe MCNP (cps) 95% conf.

27 Calibration of the the spng (SO-5-90-SN) Counts rate [pulse/600 s] H (1,71-2,35 MeV) H: 2,223 MeV Si:3,539 MeV Si:4,934 MeV Ca: 6,418MeV Si (2,67-5,03MeV) Ca (5,25-6,64MeV) Sandstone Piaskowiec Radków Limestone Wapień Józefów Sandstone Mucharz Fe: 7,631MeV 7,646 MeV Piaskowiec Mucharz Fe (6,85-10MeV) Number of channel Corelation: number of counts in the window and the concentration

28 Calibration of the the spng (SO-5-90-SN) Ca-pom [%] C 5 0 BM2 Mo2 Ca-pom =, ,96914 * Ca-chem Jo2 50 Korelacja: r =,98445 Si-pom =, , * Si-chem Ra2 Li2 Pi2 40 Korelacja: r =,99002 Fe-pom =, ,89471 * Fe-chem 1.6 Korelacja: r =,94589 Br2 Ze2 1.4 Si-pom [%] 30 el chem 20 = b el 0 i + = i= 4 Fe-pom [%] el 1.0 i b i I 0.8 eli pom Mu2 el : H, Si, Br2 Mu2 0.6 Ze210 Ra2 Ra2 Li % p.ufności Ze2 Jo2 Pi2 Jo2 BM2 Mo2 0.2 Mo2 Li % 45 p.ufności BM2 Pi2 Ca-chem 0.0 [%] Mu2 Ca, Fe Br2 Si-chem 0.0 [%] Fe-chem [%] 95% p.ufności

29 Calibration of the the spng (SO-5-90-SN) Enlargement of the range of Fe variability 5 4 C-Fe-MCNP [wt.%] 3 2 R 2 = (9 punktów) Mu2 Br2 R 2 = (21 punktów) 1 0 Ra2 Ze2 BM2 Pi2 Jo2 Mo2 Li2 95% p.ufności C-Fe-chem [wt.%]

30 Response of the the spng (SO-5-90-SN) Influence of the side effect: : a presence of chlorine in borehole. Interference of gamma ray from Cl(n,γ)Cl Mucharz2 sandstone (50 kppm NaCl in borehole) Gamma counts (cps) Cl: MeV and MeV Al: MeV (delayed gamma) Cl: MeV and MeV measurement MCNP - ENDF60 for Cl and Al MCNP - ACTIA for Cl and Al (delayed gamma-ray included) Eγ (MeV)

31 Modeling of the neutron-neutron well logging probe NNTE Near epithermal detector źródło Am-Be Far epithermal detector Near thermal detector

32 Modeling of the neutron-neutron well logging probe NNTE Problems: 1. Benchmark calculations 2. Calibration of the NNTE in Miocen standard 3. Test of infinity of Zielona Góra blocks 4. Test of the range of the detection 5. NNTE response in the ceramic block

33 Modeling of the NNTE probe: Benchmark measurement (cps) Measurement vs. MCNP simulations (ENDF/BVI.0, BVI.1, BV.0) neutron data library measurement (cps) measurement vs. MCNP simulations (ENDF/BVI.6 neutron measurement library) vs. MCNP simulations "near" 2000 thermal detector (ENDF/BVI.8 neutron library) R 2 = "near" thermal detector measurement (cps) R 2 = % conf E E E E E E E E E % conf MCNP (neutron absorptions per source neutron) "near" thermal detector R 2 = % conf. 5.0E E E E E E E E E E E E E E E E E E-06 MCNP (neutron absorptions per source neutron) MCNP (neutron absorptions per source neutron)

34 Calibration of the NNTE in Miocen standard porosity [%] The standard calibration curve for the near thermal detector NNTE logging-tool, Miocene Standard 216mm, 15 c.u.; MCNP simulation 120 y = E-13x E-09x E-06x E-03x E+00x E The standard calibration curve for the near epithermal detector NNTE logging-tool, Miocene Standard 216mm, 15 c.u.; 80 MCNP simulation 120 The standard calibration curve for the far epithermal detector 60 y = E-10x near thermal E-07x detector E-04x 3 + NNTE E-01x logging-tool, 2 - Miocene Standard 216mm, 15 c.u.; E+01x E+03 MCNP simulation y = E-12x E-09x E-06x E-03x E-01x E+01x E near epithermal detector far epithermal detector count rate [cps] porosity [%] count rate [cps] -20 porosity [%] count rate [cps]

35 Test of infinity of the Zielona Góra blocks (NNTE tool) Assumptions: Rock models from the calibration facility BGW Zielona Góra: Morawica 141 (Mo1) limestone, borehole diameter 141mm Pińczów 220 (Pi2) limestone, borehole diameter 220 mm Rock model radius: from 0 to 80 cm every 10 cm Rock model surrounded by water Tool stand-off = 0 mm Criterion for infinity infinity of the rock model: 98% of the tool signal for the infinite model

36

37 Test of infinity of the Zielona Góra blocks (NNTE tool) Near detectors Morawica 141 por % Pińczów 220 por % NNTE logging-tool detector response as a function of the radius of the rock model. Limestone; porosity 2.99%; borehole diameter 141mm; stand-off 0mm. MCNP simulation. 7.E-06 NNTE logging-tool detector response as a function of the radius of the rock model. Limestone; porosity 34.89%; borehole diameter 220mm; stand-off 0mm. MCNP simulation. 2.3.E-06 MCNP (number of neutron absorptions per starting particle) 6.E-06 5.E-06 4.E-06 3.E-06 2.E-06 1.E-06 0.E cm 40 cm near thermal detector near epithermal detector MCNP (number of neutron absorptions per starting particle) 2.1.E E E E E E E E E cm 30 cm near thermal detector near epithermal detector radius of the rock model (cm) radius of the rock model (cm)

38 Test of infinity of the Zielona Góra blocks (NNTE tool) Far detector Morawica 141 por % Pińczów 220 por % NNTE logging-tool detector response as a function of the radius of the rock model. Limestone; porosity 2.99%; borehole diameter 141mm; stand-off 0mm. MCNP simulation. 3.E-07 NNTE logging-tool detector response as a function of the radius of the rock model. Limestone; porosity 34.89%; borehole diameter 220mm; stand-off 0mm. MCNP simulation. 2.6.E-08 MCNP (number of neutron absorptions per starting particle) 3.E-07 2.E-07 2.E-07 1.E-07 5.E-08 0.E cm far epithermal detector radius of the rock model (cm) MCNP (number of neutron absorptions per starting particle) 2.4.E E E E E E E E cm far epithermal detector radius of the rock model (cm)

39 Test of infinity of the Zielona Góra blocks (NNTE tool) rock model Morawica 141 (por p.u.).) Pińczów 220 (por p.u.).) real rock model dimensions [cm] criteria 98% simulation criteria 100% φ 100 φ 100 φ x 108 φ 80 φ 100

40 Test of the range of the detection in the Zielona Góra blocks (NNTE tool) Rock models from the calibration facility BGW Zielona Góra: Morawica 141 (Mo1) limestone, borehole diameter 141mm Pińczów 220 (Pi2) limestone, borehole diameter 220 mm Rock model diameter: : 200 cm Rock model surrounded by water Cylindrical zone 5 cm thick Outer radius of the zone: from 10 cm (Mo1) or 15 cm (Pi2) to 90 cm every 5 cm Tool stand-off = 0 cm Criterion for investigation range - 99,8% of the total signal

41

42 Test of the range of the detection (NNTE tool) Near detectors Morawica 141 por p.u. Pińczów 220 por p.u. 30 Rock model Mo1 (por p.u.); rock model diameter 200 cm; borehole diameter 141mm, stand-off 0mm; thickness of the cylindrical zone 5 cm 35 Rock model Pi2 (por p.u.); rock model diameter 200 cm; borehole diameter 220mm, stand-off 0mm; thickness of the cylindrical zone 5 cm contribution to detector signal (%) cm near thermal detector near epithermal detector 60 cm contribution to detector signal (%) cm near thermal detector near epithermal detector 35 cm distance between the outer radius of the cylindrical zone and the borehole wall (cm) distance between the outer radius of the cylindrical zone and the borehole wall (cm)

43 Test of the range of the detection (NNTE tool) Far detector Morawica 141 por p.u. Pińczów 220 por p.u. 30 Rock model Mo1 (por p.u.); rock model diameter 200 cm; borehole diameter 141mm, stand-off 0mm; thickness of the cylindrical zone 5 cm 35 Rock model Pi2 (por p.u.); rock model diameter 200 cm; borehole diameter 220mm, stand-off 0mm; thickness of the cylindrical zone 5 cm contribution to detector signal (%) far epithermal detector 60 cm contribution to detector signal (%) cm far epithermal detector distance between the outer radius of the cylindrical zone and the borehole wall (cm) distance between the outer radius of the cylindrical zone and the borehole wall (cm)

44 Response of the NNTE tool in the ceramic block MCNP calculation measurement Near thermal detector tool response [cps] tool response [cps] position 150 of the tool [cm] MCNP calculation measurement position of the tool [cm] 0 Near epithermal detector MCNP calculation measurement 2005 tool response [cps] Far epithermal detector position of the tool [cm]

45 Monte Carlo simulations contra Czubek s method Tool response Semi-empirical calibration method of the neutron tool: Base: Integral neutron parameters: General Neutron Parameter Porosity A B C A, B, C - Borehole diameter GNP = L map Pr m ap Σ n ap

46 Monte Carlo simulations contra Czubek s method Semi-empirical calibration method of the neutron tool: Base: Integral neutron parameters: Slowing down length Diffusion length Macroscopic absorption cross section ( ) etc. The integral (macroscopic) neutron parameters are calculated using the base nuclear data (i.e. using the nuclear libraries)

47 Monte Carlo simulations contra Czubek s method Semi-empirical calibration method of the neutron tool F Real measurement Simulated measurement (MCNP) F = b + a GNP n GNP SLOWN, NEROTH, LMBRIN (analytical solutions + Abagian library) as above + ENDF library or GNP calculated purely Monte Carlo

48 TRnum= Bl/Dal (z obliczeń MCNP) 3,5 3,0 2,5 2,0 1,5 1,0 0,5 Uogólniona krzywa kalibracji sondy PKNN3 (6), n= TR obliczone MCNP; GNP wyznaczone z MOM3 i SIGMA3- ośrodki dwu- i trójstrefowe; regresja wielokrotna dla ośrodka Uogólniona dwustrefowego; krzywa bloki kalibracji z B10 sondy PKNN3 (6), n= TR obliczone MCNP; GNP wyznaczone z MORSE - ośrodki dwu-, trój- i czterostrefowe; regresja wielokrotna dla ośrodka dwustrefowego; y = 0,00026x 4-0,01805x 3 + 0,45898x 2 bloki z B10 3,5-5,21104x + 23,21963 R 2 = 0,99120 y = 0,00129x 3-0,00540x 2-0,80015x + 9,62829 TRnum= Bl/Dal (z obliczeń MCNP) 3,0 2,5 2,0 1,5 1,0 średnia odległość punktów od krzywej d śr = 0,62 GNP R 2 = 0,99142 średnia odległość punktów od krzywej d śr = 0,28 GNP ,5 GNP anal = L map * n ap (MOM3 i SIGMA3) ośrodek dwustrefowy (skała + otwór) GNP num = L map * n ap (MORSE ośr. dwu-, trój- i czterostrefowe) ośrodek trójstrefowy (skała + rura lub korek + otwór) uogólniona krzywa kalibracji ośrodek dla dwustrefowy ośrodka dwustrefowego (skała + otwór) ośrodek trój- (skała + korek + otwór) i czterostrefowy (skała + warstewka wody + rura + otwór) uogólniona krzywa kalibracji dla ośrodka dwustrefowego

49 Żerkowice 220; XIIIG Radków 216; XIV Pińczów 220; C Pińczów 145; B Mucharz 220; MV Mucharz 143; M81 Morawica 220; MII Morawica 141; MV Libiąż 216; III, I Libiąż 145; V Józefów 216; JII Brenna 215; B35 BIV BIVa Brenna 141 B29.8 B42 B40 Biała Marianna 220 BMG KAlSi3O8 (ORTOKLAZ) CaMg(CO3)2 por. 20% CaCO3 por. 20% SiO2 por. 20% CaMg(CO3)2 por. 0% CaCO3 por. 0% SiO2 por. 0% H2O SLOWN Ls cm Ls cm MORSE (pulely Monte-Carlo) Slowing down length [cm]

50 Żerkowice 220; XIIIG Radków 216; XIV Pińczów 220; C Pińczów 145; B Mucharz 220; MV Mucharz 143; M81 Morawica 220; MII Morawica 141; MV Libiąż 216; III, I NEROTH MORSE Ld cm Ld cm (purely Monte-Carlo) Libiąż 145; V Józefów 216; JII Brenna 215; B35 BIV BIVa Brenna 141 B29.8 B42 B40 Biała Marianna 220 BMG KAlSi3O8 (ORTOKLAZ) CaMg(CO3)2 por. 20% CaCO3 por. 20% SiO2 por. 20% CaMg(CO3)2 por. 0% CaCO3 por. 0% SiO2 por. 0% H2O Diffusion length [cm]

51 Nomogram do wyznaczania Σ a matryc mioceńskich na podstawie pomiarów sondą NNTE. Parametrem krzywych jest PorPozBter [% jsm]. Średnica otworu 216 mm. Wykres uzyskany na drodze symulacji MCNP [% jsm] 8 [% jsm] [% jsm] 16 [% jsm] Σ a matrycy mioceńskiej [cu] DporSigA [%] 20 [% jsm] 25 [% jsm] 30 [% jsm] 35 [% jsm] 40 [% jsm] 45 [% jsm] 50 [% jsm] 55 [% jsm] 60 [% jsm] 70 [% jsm] 80 [% jsm] 90 [% jsm]

52 NNTE response in the multi-layer system r Continuous change of the parameters of the wellbore zone along the radial dimension

53 NNTE response in the multi-layer system Brine Virgin zone Filtration zone Borehole (brine) Rock matrix Gas Formation fluid NNTE tool

54 NNTE response in the multi-layer system Virgin zone: Miocen standard Skład: SiO 2 : %; Al 2 O 3 : 7 %; Fe 2 O 3 : 2 %; CaO: %; K 2 O: 1.80 %; H 2 O: 1.20 %; CO 2 : 8 % Σ a = 15 c.u. (for rock matrix) Density: ρ r = 2.63 g cm -3 Porosity: 20 p.u. Examples for analytical calculation Temperature: 20.5 C Pressure : 0.1 MP Gas saturation of the virgin zone: CH 4 density: ρ g = 0.1 g cm -3 Example 1: H 2 O + CH 4, S w + S g = 100% Example 2: solanka 50 kppm NaCl + CH 4, S w + S g = 100% Borehole fluid: 10 kppm NaCl Density ρ b = g cm -3 Filtration zone: Miocen standard 20 p.u., 100 % saturated of borehole fluid Thickness G f = 0, 50, 100, 200 mm Borehole diam.: 216 mm Tool diam.: 89 mm Stand-off: 0 mm

55 NNTE response in the multi-layer system Analytical approximate solution Near thermal detector [cps] Gf = 0 Gf = 50 mm Gf = 100 mm Gf = 200 mm NNTE tool response as the function of the thickness Gf of the filtration zone Example Gas saturation of the virgine zone [%]

56 NNTE response in the multi-layer system Analytical approximate solution 2.5 Gf - thickness of the filtration zone (Near / Far) Epi Gf = 0 mm Gf = 50 mm Gf = 100 mm Gf = 200 mm Example Gas saturation of the virgin zone [%]

57 NNTE response in the multi-layer system Monte Carlo solution NNTE tool Borehole and brine Filtration zone Virgin zone

58 NNTE response in the multi-layer system Normalized detector response of the NNTE tool Near thermal detector Sg = 90 % { Sg = 50 % { Sg = 10 % { LMBRIN MCNP LMBRIN MCNP LMBRIN MCNP Thickness of the filtration zone [mm]

59 NNTE response in the multi-layer system Near-to-Far epith. det Example Example 1 NNTE tool. Ratio of the detectors response: Near to Far epithermal detectors MCNP LMBRIN 7 % < 100% < LMBRIN Sg=90% { Sg=50% { Sg=10% { 20% LMBRIN MCNP LMBRIN MCNP LMBRIN MCNP Thickness of the filtration zone [mm]

60 Future belongs to Monte Carlo

61