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Environmental ScatterWorkshop in Bologna July 14-16 2003
P6 1QUADOSQUADOS
Problem 6Environmental Scatter
Jean-Louis Chartier1 and Bernd R.L.Siebert2
Intercomparison on the Usage of Computational Codes in Radiation Dosimetry
Workshop in Bologna-Italy July 14 -16 2003
(2) Physikalisch-Technische Bundesanstalt, Braunschweig, Germany
(1) Institut de Radioprotection et de Sûreté Nucléaire, Fontenay aux Roses, France
Environmental ScatterWorkshop in Bologna July 14-16 2003
P6 2QUADOSQUADOS
Table of ContentThe problemNomenclatureResults for task 1, 2, 3 and 4Physics of the problemParticipation and approachesDetailed discussion of computing
• directional fluence and• contributions from walls, floor and ceiling.
OralsSummary and Conclusion
If there is a questionor the needto discuss,
please interrupt,anytime!
Orals will be given by Tom McLean and Miloslav Králik
Environmental ScatterWorkshop in Bologna July 14-16 2003
P6 3QUADOSQUADOS
10-9 10-8 10-7 10-6 10-5 10-4 10-3 10-2 10-1 100 1010.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8Direct
241AmBe(α,n)
252Cf(sf) 252Cf(sf), moderated (15 cm D2O) + 1 mm Cd
E ϕ E
/ ϕ
E / MeV
Environmental Scatter: Workplace Fields
10-9 10-8 10-7 10-6 10-5 10-4 10-3 10-2 10-1 100 1010.00
0.05
0.10
0.15
0.20Inscattered
241AmBe(α,n)
252Cf(sf) 252Cf(sf), moderated
(15 cm D2O) + 1 mm Cd
E ϕ E
/ ϕ
E / MeV
Inscattered: 241AmBe (α,n) 252Cf(sf) 252Cf(sf),moderated
Work place neutron fieldsfor the Calibrationof Personal Dosimeterscan be “mocked up” in the laboratory
Sources, direct: 241AmBe (α,n) 252Cf(sf) 252Cf(sf),moderated
Environmental ScatterWorkshop in Bologna July 14-16 2003
P6 4QUADOSQUADOS
Environmental Scatter: Workplace Fields
Shadow ConesShadow Cones
“BUNKER” operated by (Photos by Urbach)
Monitor LB6411
For information on calibrations:[email protected]
Position controlling
Environmental ScatterWorkshop in Bologna July 14-16 2003
P6 5QUADOSQUADOS
Problem 6: Environmental Scatter
Shadow coneShadow conewith two layerswith two layers
Position 1Position 1
Position 2Position 2
252Cf- isotropic252Cf- isotropicpoint source inpoint source incentrecentre
y
xx
A bare 252Cf neutron source is located at the centre of a concrete walled calibration room.
Task 1 :Compute thefluence as function of energyin positions 1 & 2
Task 2:Compute thefluence as function of energyand angle in positions 1 & 2
Task 3: Compute thecontributions from air , walls,floor and ceiling in positions1 & 2Task 4: Compute the influence of a change in the water content in concrete in positions 1 & 2
Task 1: Compute thefluence as function of energyin positions 1 & 2
Task 2: Compute thefluence as function of energyand angle in positions 1 & 2Task 3: Compute thecontributions from air , walls,floor and ceiling in positions1 & 2
Figure is not scaled
Task 4: Compute the influence of a change in the water content in concrete in positions 1 & 2
Environmental ScatterWorkshop in Bologna July 14-16 2003
P6 6QUADOSQUADOS
Nomenclature (1/5)
ICRU Report 60: Fundamental Quantities and Units for Ionizing Radiation BIPM : Le Système international d´unités (7e édition 1998)
The particle number, N, is the number of particles that are emitted, transferred, or received. The unit is 1.Note: The distribution, NE , of the particle number with respect to energy is given by NE =dN/dE
The fluence , Φ, is the quotient of dN by da , where dN is the number of particles incident on a sphere of cross sectional area da, thus The SI-unit is m-2,but cm-2 is ok, too. a
Nd
d=ΦNote: The distribution, ΦE , of the fluence with respect to energy is given by ΦE = dΦ/dE, the unit is m -2 eV -1.
The flux , N, is the quotient of dN by dt, where dN is the increment of the particle number in the time interval dt, thus N = dN/dt ; unit is s-1.
.
Environmental ScatterWorkshop in Bologna July 14-16 2003
P6 7QUADOSQUADOS
ϑϑ
t=h/|cos(ϑ)|t=h/|cos(ϑ)|
hh
Surface sSurface ss=2πr2s=2πr2
2r2r
track lengthtrack length
ϕϕs=πr2
Nomenclature (2/5) Relation between thenumber of particles, N, that cross a surface and the fluence in a cell
Practical definition of fluence in a cell for use with transportcalculations: The fluence, Φ , in a cell is the quotient of thesum of track lengths ti and the volume, Vcell, of that cell, thus
∑=
=N
iitV 1cell
1Φ
Since Vcell= h.s
∑=
=N
i icoss 1
11ϑ
Φ
cos|
|
hti
i ϑ= ( ) [ ]1
1+
=
− ∈= ∑ jji
n
iij s,|
sϑϑϑϑΦ cocoscos wherecos|1
1
Environmental ScatterWorkshop in Bologna July 14-16 2003
P6 8QUADOSQUADOS
( )[ ] [ ] ( )|cocos|21 co,coscos 1 cosE 1 1 cos ++ϑ ϑ+ϑϑϑ∈ϑ=ϑ ∑ jj
n
ijjij ss
ng
j
Nomenclature (3/5)
( )jjj ϑ−ϑ⋅π⋅= + coscos2∆ 1Ω
j
J
jj
ΩΦΦ Ω ∆1
⋅= ∑=
( ) [ ]11
+− ∈= ∑ jji
n
iij s,|
sϑϑϑϑΦ cocoscos wherecos|1
Presentation per sr
jjjΩΦΦΩ
-1∆⋅=
]E[cos
j
jj s
nϑ
Φ⋅
≈ ΦTally 2 ≈ ΦTally 4 or 5
if fluence is isotropic then
∑=
⋅=J
jjn
s 1
2Φ
< cos ϑ >=0.5
[ ] jcos,coscos nnjj
:=+∈ 1ϑϑϑ
nj is given in MCNP by tally F1
if fluence is isotropic in that bin
E is expectation value
=
Environmental ScatterWorkshop in Bologna July 14-16 2003
P6 9QUADOSQUADOS
Nomenclature (4/5)
Generally for MCNP and MCNPX:• a fluence estimator (F4 or F5) should be used for tasks 1,3 and 4• and a particle estimator (F1) [or a fluence estimator (F2)] in conjunction with cos ϑ sorting for task 2• all results should be normalised to one source neutron.
Mean track length for parallel incidence on sphere is 4/3 r ⇒ Φ = 1/ π r 2 but every track is counted twice (entering and leaving the sphere).
Most participants used MCNP or MCNPX, one used TRIPOLI
Some comments on MCNP (1/2)
F4 and F5 compute track length sum divided by the specified volume.
F1 (with surface): normalise by dividing by area and mean cosϑ
F1 (with sphere): normalise by dividing by area = 2 π r 2 with F2 only by 2
WHY ?
Environmental ScatterWorkshop in Bologna July 14-16 2003
P6 10QUADOSQUADOS
Nomenclature (5/5)
MCNP-convention: upper bin energy, group fluence !Several particpants were not aware of this.Group fluence to lethargy representation via ln(Ei / Ei-1).
Most participants used MCNP or MCNPX, one used TRIPOLI
Cumulative distribution
Flagging allows to partially reconstruct the geometrical history of a neutron
Multiple scattering contributions can be separated, one should alwaysat least view the uncollided fraction for any tally.
Some comments on MCNP (2/2)
( ) ( ) EEEE
E
J
jjJ d
01∫∑ =≈=
=
ΦΦϕΦ( ) ( )
jj
jjj EE
EE
′+′
′+′′ −
−=
1
1 ΦΦϕ
can be used to re-bin the results.
Environmental ScatterWorkshop in Bologna July 14-16 2003
P6 11QUADOSQUADOS
Results for Task 1 (1/7) Task 1:Compute the fluence as functionof energy in position 1
10-9 10-8 10-7 10-6 10-5 10-4 10-3 10-2 10-1 100 101
E / MeV
0
2.10-7
4.10-7
6.10-7
8.10-7
10-6
EΦE(
E ) /
cm2
ZZCCGGBBDDFFHHIIJJL without thermalL without thermalMM
with equal bin size
G
D
Environmental ScatterWorkshop in Bologna July 14-16 2003
P6 12QUADOSQUADOS
Results for Task 1 (2/7) Task 1:Compute the fluence as functionof energy in position 1
10-2 10-1 100 101
E / MeV
0
2.10-7
4.10-7
6.10-7
EΦE(
E) /
cm2
ZZCCGGBBDDFFHHIIJJL without thermalL without thermalMM
with equal bin size=original
D
J
Environmental ScatterWorkshop in Bologna July 14-16 2003
P6 13QUADOSQUADOS
Results for Task 1 (3/5) Task 1:Compute the fluence as functionof energy in position 1
10-9 10-8 10-7 10-6 10-5 10-4 10-3 10-2 10-1 100 101
E / MeV
0
2.10-7
4.10-7
6.10-7
8.10-7
10-6
EΦE(
E ) /
cm2
ZZE * 4,2E * 4,2KKN * 4N * 4A * 4 πA * 4 π
with equal bin size
Environmental ScatterWorkshop in Bologna July 14-16 2003
P6 14QUADOSQUADOS
Results for Task 1 (4/7) Task 1:Compute the fluence as functionof energy in position 1
10-9 10-8 10-7 10-6 10-5 10-4 10-3 10-2 10-1 100 101
E / MeV
0
10-6
2.10-6
3.10-6
4.10-6
5.10-6
Φ (E
) / c
m2
ZZCCGGBBDDEthermal: 1 binEthermal: 1 binFFHthermal: 1 binHthermal: 1 binIIJJ
KKLwithout thermalLwithout thermalMMNfrom tally F2Nfrom tally F2AA
with equal bin size
( ) ( ) EEEE
E
J
jjJ d
01∫∑ =≈=
=
ΦΦϕΦ
Environmental ScatterWorkshop in Bologna July 14-16 2003
P6 15QUADOSQUADOS
Task 1:Compute the fluence as functionof energy in position 1
Results for Task 1 (5/7)
per bintotal
E n 0 .4 1 4 1 1 0 1 0 0 1 1 5e V k e V k e V M e V M e V M e V
A .1 2 .0 9 .0 9 .0 8 .0 7 .0 9B 1 .0 0 1 .0 1 1 .0 0 1 .0 1 1 .0 2 1 .0 3C .9 7 1 .0 0 .9 8 1 .0 0 1 .0 0 1 .0 1D .9 9 .9 5 1 .0 1 .8 7 .9 5 .9 5E .7 7 .3 7 .3 0 .2 2 .1 9 .2 4F 1 .0 0 1 .0 1 .9 8 .9 9 1 .0 1 1 .0 0G 1 .0 6 1 .0 2 .9 8 1 .0 0 1 .0 0 1 .0 0H 1 .0 0 1 .0 0 .9 8 1 .0 0 1 .0 0 1 .0 0
I 1 .0 0 1 .0 0 .9 9 1 .0 0 1 .0 0 1 .0 0J 1 .0 5 1 .0 6 1 .0 5 1 .0 6 1 .0 6 1 .0 6K .0 0 .8 2 .7 8 .7 6 .7 6 1 .4 8L .0 0 1 .0 1 .9 9 1 .0 0 1 .0 1 1 .0 0
M 1 .0 1 1 .0 0 .9 8 1 .0 0 1 .0 0 1 .0 0N .8 1 .3 9 .3 2 .2 3 .2 0 .2 5Z 1 8 3 2 6 3 0 .3 2 2 6 .1 2 9 9 .7 6 9 4 .6 3 4 9 .0Z 1 8 3 2 2 4 6 3 2 6 8 9 2 9 8 8 3 6 8 3 4 0 3 2 Z .109
Environmental ScatterWorkshop in Bologna July 14-16 2003
P6 16QUADOSQUADOS
E n 0 .4 1 4 1 1 0 1 0 0 1 1 5e V ke V ke V M e V M e V M e V
B 1 .0 0 1 .0 0 1 .0 1 1 .0 0 1 .0 0 1 .0 1C .9 7 .9 9 .9 9 .9 9 .9 9 1 .0 0D .9 8 .9 4 .9 6 .8 6 .8 8 .9 9E .7 5 .3 4 .2 8 .2 1 .1 6 .2 0F .9 9 1 .0 1 1 .0 0 1 .0 0 1 .0 0 1 .0 1G 1 .0 6 1 .0 2 1 .0 0 1 .0 0 1 .0 0 1 .0 0H 1 .0 0 1 .0 0 1 .0 0 1 .0 0 1 .0 0 1 .0 0I 1 .0 0 1 .0 0 1 .0 0 1 .0 0 1 .0 0 1 .0 0J 1 .0 5 1 .0 6 1 .0 6 1 .0 6 1 .0 6 1 .0 5K .0 0 .8 2 .7 9 .7 7 .7 7 1 .5 0L .0 0 1 .0 0 1 .0 0 1 .0 0 1 .0 0 1 .0 0
M .9 9 1 .0 2 1 .0 6 1 .0 2 1 .0 0 1 .0 1N .7 9 .3 6 .3 0 .2 2 .1 7 .2 1Z 1 8 1 8 6 1 9 .3 2 1 6 .4 2 8 7 .3 6 4 1 .2 3 0 6 .0Z 1 8 1 8 2 4 3 7 2 6 5 3 2 9 4 1 3 5 8 2 3 8 8 8
Results for Task 1 (6/7) Task 1:Compute the fluence as functionof energy in position 2
per bintotalZ .109
Environmental ScatterWorkshop in Bologna July 14-16 2003
P6 17QUADOSQUADOS
Results for Task 1 (7/7) Task 1:Compute the fluence as functionof energy in position 1&2
1E-7 1E-5 1E-3 0.1 101E-13
1E-11
1E-9
1E-7
1E-5
1E-3
0.1
10
Flue
nce
(par
ticle
s cm
-2M
eV-1)
Neutron energy (MeV)
Det. 1 Det. 2 Det. 1 w/ cone Det. 2 w/ cone
Participant I Thedifferencebetween
thevariousspectra
is used tomock up
work placespectra
(environmental)[see task 4, F25]
Environmental ScatterWorkshop in Bologna July 14-16 2003
P6 18QUADOSQUADOS
Results for Task 2 (1/3) Task 2:Compute the fluence as functionof energy and angle in position 1
10-9 10-8 10-7 10-6 10-5 10-4 10-3 10-2 10-1 100 101
E / MeV
0
2.10-7
4.10-7
6.10-7
8.10-7
10-6
EΦE(
E) /
(cm
2 sr)
(Z / 170 cm)Tally F5(Z / 170 cm)Tally F5cosϑ ε [-1,-0.866]cosϑ ε [-1,-0.866]cosϑ ε [-0.866,-0.5]cosϑ ε [-0.866,-0.5]cosϑ ε [-0.5,0]cosϑ ε [-0.5,0]cosϑ ε [ 0, 0.5]cosϑ ε [ 0, 0.5]cosϑ ε [ 0.5, 0.866]cosϑ ε [ 0.5, 0.866]cosϑ ε [ 0.866, 0]cosϑ ε [ 0.866, 0](Z / 170)Tally F1(Z / 170)Tally F1
Total Fluence and Total Fluence and Fluence in Angular Bins as ComputedFluence in Angular Bins as Computed
10-9 10-8 10-7 10-6 10-5 10-4 10-3 10-2 10-1 100 101
E / MeV
0
2.10-8
4.10-8
6.10-8
8.10-8
EΦE(
E) /
(cm
2 sr)
(Z / 170 cm)Tally F5(Z / 170 cm)Tally F5cosϑ ε [-1,-0.866]cosϑ ε [-1,-0.866]cosϑ ε [-0.866,-0.5]cosϑ ε [-0.866,-0.5]cosϑ ε [-0.5,0]cosϑ ε [-0.5,0]cosϑ ε [ 0, 0.5]cosϑ ε [ 0, 0.5]cosϑ ε [ 0.5, 0.866]cosϑ ε [ 0.5, 0.866]cosϑ ε [ 0.866, 0]cosϑ ε [ 0.866, 0](Z / 170)Tally F1(Z / 170)Tally F1
Total Fluence and Total Fluence and Fluence in Angular Bins per SteradianFluence in Angular Bins per Steradian
10-9 10-8 10-7 10-6 10-5 10-4 10-3 10-2 10-1 100 101
E / MeV
0
2.10-8
4.10-8
6.10-8
8.10-8
E ΦE(
E) /
(cm
2 sr)
(I / 170 cm)Tally F5(I / 170 cm)Tally F5cosϑ ε [-1,-0.866]cosϑ ε [-1,-0.866]cosϑ ε [-0.866,-0.5]cosϑ ε [-0.866,-0.5]cosϑ ε [-0.5,0]cosϑ ε [-0.5,0]cosϑ ε [ 0, 0.5]cosϑ ε [ 0, 0.5]cosϑ ε [ 0.5, 0.866]cosϑ ε [ 0.5, 0.866]cosϑ ε [ 0.866, 0]cosϑ ε [ 0.866, 0](I / 170)Tally F1(I / 170)Tally F1
Total Fluence and Total Fluence and Fluence in Angular Bins per SteradianFluence in Angular Bins per Steradian
10-9 10-8 10-7 10-6 10-5 10-4 10-3 10-2 10-1 100 101
E / M eV
0
2 .10-8
4 .10-8
6 .10-8
8 .10-8
EΦE(
E ) /
(cm
2 sr)
(Z / 170 cm )T ally F 5(Z / 170 cm )T ally F 5cosϑ ε [-1 ,-0 .866]cosϑ ε [-1 ,-0 .866]cosϑ ε [-0 .866,-0 .5]cosϑ ε [-0 .866,-0 .5]cosϑ ε [-0 .5 ,0]cosϑ ε [-0 .5 ,0]cosϑ ε [ 0 , 0 .5]cosϑ ε [ 0 , 0 .5]cosϑ ε [ 0 .5 , 0 .866]cosϑ ε [ 0 .5 , 0 .866]cosϑ ε [ 0 .866, 0]cosϑ ε [ 0 .866, 0](Z / 170)T ally F1(Z / 170)T ally F1
T otal F luence and T otal F luence and F luence in A ngu lar B ins per S terad ianF luence in A ngu lar B ins per S terad ian
10-9 10-8 10-7 10-6 10-5 10-4 10-3 10-2 10-1 100 101
E / M eV
0
2.10-7
4.10-7
6.10-7
8.10-7
10-6
EΦE(
E) /
(cm
2 sr)
(Z / 170 cm)Tally F5(Z / 170 cm)Tally F5cosϑ ε [-1,-0.866]cosϑ ε [-1,-0.866]cosϑ ε [-0.866,-0.5]cosϑ ε [-0.866,-0.5]cosϑ ε [-0.5,0]cosϑ ε [-0.5,0]cosϑ ε [ 0, 0.5]cosϑ ε [ 0, 0.5]cosϑ ε [ 0.5, 0.866]cosϑ ε [ 0.5, 0.866]cosϑ ε [ 0.866, 0]cosϑ ε [ 0.866, 0](Z / 170)Tally F1(Z / 170)Tally F1
Total Fluence and Total Fluence and Fluence in Angular Bins as ComputedFluence in Angular Bins as Computed
10-9 10-8 10-7 10-6 10-5 10-4 10-3 10-2 10-1 100 101
E / MeV
0
2.10-8
4.10-8
6.10-8
8.10-8
E ΦE(
E) /
(cm
2 sr)
( G/ 170 cm)Tally F5( G/ 170 cm)Tally F5cosϑ ε [-1,-0.866]cosϑ ε [-1,-0.866]cosϑ ε [-0.866,-0.5]cosϑ ε [-0.866,-0.5]cosϑ ε [-0.5,0]cosϑ ε [-0.5,0]cosϑ ε [ 0, 0.5]cosϑ ε [ 0, 0.5]cosϑ ε [ 0.5, 0.866]cosϑ ε [ 0.5, 0.866]cosϑ ε [ 0.866, 0]cosϑ ε [ 0.866, 0](G / 170)Tally F1(G / 170)Tally F1
Total Fluence and Total Fluence and Fluence in Angular Bins per SteradianFluence in Angular Bins per Steradian
Environmental ScatterWorkshop in Bologna July 14-16 2003
P6 19QUADOSQUADOS
Task 2:Compute the fluence as functionof energy and angle in positions 1 & 2
Angle Participantsdegree B C G I L Z
180-150 .93 .94 .26 .94 .89 .95150-120 1.04 1.05 .39 1.05 1.05 1.05120- 90 .89 .91 1.71 .91 .88 .89 90- 60 1.07 1.07 1.85 1.06 1.08 1.08 60- 30 .99 1.00 .38 1.00 1.03 1.00 30- 0 1.10 1.02 .27 1.03 1.05 1.03sum/F4 1.00 1.00 1.07 1.00 1.00 1.00
Results for Task 2 (2/3)
Angle Participantsdegree B C G I L Z
180-150 .78 .77 .21 .78 .61 .78150-120 .90 .90 .35 .93 .86 .91120- 90 1.12 1.11 1.73 1.05 1.09 1.12 90- 60 1.02 1.01 1.72 .99 .98 1.03 60- 30 1.08 1.09 .41 1.10 1.15 1.08 30- 0 1.06 1.05 .28 1.06 1.09 1.05sum/F4 1.02 1.01 1.03 1.00 1.00 1.02
Position 1 (170 cm)
Position 2 (300 cm)
B,C,Z: F1 (surface)
I,L : F1 (volume)
G : F2 (volume)
?
Environmental ScatterWorkshop in Bologna July 14-16 2003
P6 20QUADOSQUADOS
Angular dependence of neutron fluence at position 1
1,0E-12
1,0E-11
1,0E-10
1,0E-09
1,0E-08
1,0E-07
1,0E-06
1,0E-05
1,0E-10 1,0E-09 1,0E-08 1,0E-07 1,0E-06 1,0E-05 1,0E-04 1,0E-03 1,0E-02 1,0E-01 1,0E+00 1,0E+01 1,0E+02
Neutron Energy (MeV)
E p
hi(E
) per
sou
rce
neut
ro
150-180 degrees120-150 degrees 90 -120 degrees 60- 90 degrees 30- 60 degrees 0- 30 degrees
Note : Data not corrected for double counting I.e. divide by 2 to get absolute f luence in each cosine bin
Taken from participant G
10-9 10-8 10-7 10-6 10-5 10-4 10-3 10-2 10-1 100 101
E / MeV
10-9
10-8
10-7
10-6
EΦE(
E) /
(cm
2 sr)
cosϑ ε [-1,-0.866]cosϑ ε [-1,-0.866]cosϑ ε [-0.866,-0.5]cosϑ ε [-0.866,-0.5]cosϑ ε [-0.5,0]cosϑ ε [-0.5,0]cosϑ ε [ 0, 0.5]cosϑ ε [ 0, 0.5]cosϑ ε [ 0.5, 0.866]cosϑ ε [ 0.5, 0.866]cosϑ ε [ 0.866, 0]cosϑ ε [ 0.866, 0]
10-9 10-8 10-7 10-6 10-5 10-4 10-3 10-2 10-1 100 101
E / MeV
10-9
10-8
10-7
10-6
E ΦE(
E ) /
(cm
2 sr)
cosϑ ε [-1,-0.866]cosϑ ε [-1,-0.866]cosϑ ε [-0.866,-0.5]cosϑ ε [-0.866,-0.5]cosϑ ε [-0.5,0]cosϑ ε [-0.5,0]cosϑ ε [ 0, 0.5]cosϑ ε [ 0, 0.5]cosϑ ε [ 0.5, 0.866]cosϑ ε [ 0.5, 0.866]cosϑ ε [ 0.866, 0]cosϑ ε [ 0.866, 0]
Results for Task 2 (3/3) Task 2:Compute the fluence as functionof energy and angle in position 1
Angular dependence of neutron fluence at position 1
1,0E-12
1,0E-11
1,0E-10
1,0E-09
1,0E-08
1,0E-07
1,0E-06
1,0E-05
1,0E-10 1,0E-09 1,0E-08 1,0E-07 1,0E-06 1,0E-05 1,0E-04 1,0E-03 1,0E-02 1,0E-01 1,0E+00 1,0E+01 1,0E+02
Neutron Energy (MeV)
E p
hi(E
) per
sou
rce
neut
ro
150-180 degrees120-150 degrees 90 -120 degrees 60- 90 degrees 30- 60 degrees 0- 30 degrees
Note : Data not corrected for double counting I.e. divide by 2 to get absolute f luence in each cosine bin
G ?
Environmental ScatterWorkshop in Bologna July 14-16 2003
P6 21QUADOSQUADOS
Results for Task 3 (1/3)Task 3: Compute the contributions fromair , walls, floor and ceiling in pos. 1
B F I M Zair 13.78 13.40 14.42 1.59 13.65near sensor 25.58 25.80 25.83 9.36 25.83opp. ssensor 6.63 6.57 6.49 3.68 6.48side 1 12.20 12.22 14.32 10.53 12.25side 2 12.16 12.18 14.32 10.53 12.23floor 14.27 14.29 12.31 6.44 14.34ceiling 14.25 14.33 12.32 6.45 14.32
Normalised to total fluence for each author
Most results that usedflagging agree very well.Results for position 2 are of the same quality, in general.
See pages 38 & 39 andAppendix
Side 1 and 2 andfloor and ceiling
are by virtue of thesymmetry of the problemexpected to be identical
Environmental ScatterWorkshop in Bologna July 14-16 2003
P6 22QUADOSQUADOS
Results for Task 3 (2/3)Task 3: Compute the contributions fromair , walls, floor and ceiling in pos. 1
10-9 510-8 510-7 510-6 510-5 510-4 510-3 510-2 510-1 5100 5101
E / MeV 0
3.10-7
EΦE(
E ) /
(cm
2 sr)
Z airZ airZ wall near sensorZ wall near sensorZ wall opposite sensorZ wall opposite sensorZ side wallsZ side wallsZ floor and ceilingZ floor and ceiling
Environmental ScatterWorkshop in Bologna July 14-16 2003
P6 23QUADOSQUADOS
10-9 510-8 510-7 510-6 510-5 510-4 510-3 510-2 510-1 5100 5101
E / MeV 0
3.10-7
EΦE(
E) /
(cm
2 sr)
B wall near sensorB wall near sensorF wall near sensorF wall near sensorI wall near sensorI wall near sensorM wall near sensorM wall near sensorZ wall near sensorZ wall near sensor
10-9 510-8 510-7 510-6 510-5 510-4 510-3 510-2 510-1 5100 5101
E / MeV 0
3.10-7
EΦE(
E ) /
(cm
2 sr)
B airB airF airF airI airI airM airM airZ airZ air
10-9 510-8 510-7 510-6 510-5 510-4 510-3 510-2 510-1 5100 5101
E / MeV 0
3.10-7
EΦE(
E) /
(cm
2 sr)
B wall opposite sensorB wall opposite sensorF wall opposite sensorF wall opposite sensorI wall opposite sensorI wall opposite sensorM wall opposite sensorM wall opposite sensorZ wall opposite sensorZ wall opposite sensor
10-9 510-8 510-7 510-6 510-5 510-4 510-3 510-2 510-1 5100 5101
E / MeV 0
3.10-7
EΦE(
E) /
(cm
2 sr)
B side wallsB side wallsF side wallsF side wallsI side wallsI side wallsM side wallsM side wallsZ side wallsZ side walls
10-9 510-8 510-7 510-6 510-5 510-4 510-3 510-2 510-1 5100 5101
E / MeV 0
3.10-7
EΦE(
E) /
(cm
2 sr)
B floor & ceilingB floor & ceilingF floor & ceilingF floor & ceilingI floor & ceilingI floor & ceilingM floor & ceilingM floor & ceilingZ floor & ceilingZ floor & ceiling
Results for Task 3 (3/3)Task 3: Compute the contributions fromair , walls, floor and ceiling in pos. 1
10-9 510-8 510-7 510-6 510-5 510-4 510-3 510-2 510-1 5100 5101
E / MeV 0
3.10-7
EΦE(
E) /
(cm
2 sr)
B airB airF airF airI airI airM airM airZ airZ air
10-9 510-8 510-7 510-6 510-5 510-4 510-3 510-2 510-1 5100 5101
E / M eV 0
3.10-7
EΦE(
E) /
(cm
2 sr)
B w all opposite sensorB w all opposite sensorF w all opposite sensorF w all opposite sensorI w all opposite sensorI w all opposite sensorM w all opposite sensorM w all opposite sensorZ w all opposite sensorZ w all opposite sensor
10-9 510-8 510-7 510-6 510-5 510-4 510-3 510-2 510-1 5100 5101
E / MeV 0
3.10-7
EΦE(
E) /
(cm
2 sr)
B side wallsB side wallsF side wallsF side wallsI side wallsI side wallsM side wallsM side wallsZ side wallsZ side walls
10-9 510-8 510-7 510-6 510-5 510-4 510-3 510-2 510-1 5100 5101
E / MeV
0
3.10-7
EΦE(
E) /
(cm
2 sr)
B floor & ceilingB floor & ceilingF floor & ceilingF floor & ceilingI floor & ceilingI floor & ceilingM floor & ceilingM floor & ceilingZ floor & ceilingZ floor & ceiling
10-9 510-8 510-7 510-6 510-5 510-4 510-3 510-2 510-1 5100 5101
E / MeV 0
3.10-7
EΦE(
E) /
(cm
2 sr)
B wall near sensorB wall near sensorF wall near sensorF wall near sensorI wall near sensorI wall near sensorM wall near sensorM wall near sensorZ wall near sensorZ wall near sensor
Environmental ScatterWorkshop in Bologna July 14-16 2003
P6 24QUADOSQUADOS
Task 4: Compute the influence ofa change in the water content inconcrete in positions 1 & 2
Results for Task 4 (1/4)
Normalised to normal water content for each authorH2O B C F G I L Z -1% 103.90 - - 103.78 - 107.66 104.06 +1% 96.41 96.78 96.46 96.74 97.04 92.54 96.47 +2% - 93.99 93.77 94.02 94.29 88.16 93.80 +3% - 91.46 91.62 91.66 - - 91.13
H2O B C F G I L Z -1% 104.27 - - 103.91 - 110.11 104.11 +1% 96.83 96.64 97.12 96.72 96.81 85.81 96.68 +2% - 93.50 93.95 94.76 94.42 80.77 93.52 +3% - 90.91 91.27 91.26 - - 90.93
Normalised to normal water content for each author
Environmental ScatterWorkshop in Bologna July 14-16 2003
P6 25QUADOSQUADOS
Z .106
Normalised to Z within each energy bin-1 0.414 eV 1 keV 10 keV 100 keV 1 MeV 16 MeV B 1.00 1.00 1.01 1.01 1.02 1.03 G 1.06 1.02 .99 .99 1.00 1.00 L .00 1.00 1.00 1.00 1.01 1.01 Z 1.82 0.68 0.24 0.33 0.75 0.37+1 B 1 . 00 1 . 01 1 . 03 1 . 01 1 . 02 1 . 03 C . 97 1 . 00 1 . 02 1 . 01 1 . 01 1 . 01 F 1 . 00 1 . 00 1 . 01 . 99 1 . 01 1 . 00 G 1 . 06 1 . 02 1 . 02 1 . 00 1 . 00 1 . 00 I 1 . 00 1 . 01 1 . 02 1 . 01 1 . 01 1 . 01 L . 00 . 99 1 . 01 . 99 1 . 00 1 . 00 Z 1 . 83 0 . 59 0 . 20 0 . 28 0 . 65 0 . 33
Results for Task 4 (2/4)D
ecrease with increasing energy
Task 4: Compute the influence ofa change in the water content inconcrete in positions 1 & 2
Z 0.414 eV 1 keV 10 keV 100 keV 1 MeV 16 MeV -1% 1.80 .67 .24 .32 .70 .32 +1% 1.82 .62 .22 .29 .64 .31 +2% 1.83 .58 .20 .27 .60 .29 +3% 1.81 .52 .18 .23 .53 .27
Environmental ScatterWorkshop in Bologna July 14-16 2003
P6 26QUADOSQUADOS
Results for Task 4 (3/4)
10-9 10-8 10-7 10-6 10-5 10-4 10-3 10-2 10-1 100 101
E / MeV
0
2.10-7
4.10-7
6.10-7
8.10-7
10-6
E ΦE(
E ) /
cm2
-1%-min-1%-min-1%-max-1%-max 0%-min 0%-min 0%-max 0%-max+1%-min+1%-min+1%-max+1%-max
Influence of H20 -content in concreteInfluence of H20 -content in concrete(Sensor position 1 in problem P6)(Sensor position 1 in problem P6)
10-9 10-8 10-7 10-6 10-5 10-4 10-3 10-2 10-1 100 101
E / MeV
0
2.10-7
4.10-7
6.10-7
8.10-7
10-6
E ΦE(
E) /
cm2
-1%-min-1%-min-1%-max-1%-max 0%-min 0%-min 0%-max 0%-max+1%-min+1%-min+1%-max+1%-max
Influence of H20 -content in concreteInfluence of H20 -content in concrete
(Sensor position 1 in problem P6)(Sensor position 1 in problem P6)
( ) ?∆
∆∆ OH2
=
⋅=
Φ
αΦ
uc
( ) ( )( )( ) ?∆
∆∆ OH2
=
⋅=
EucEE
E
E
Φ
αΦ
Task 4: Compute the influence ofa change in the water content inconcrete in positions 1 & 2
Environmental ScatterWorkshop in Bologna July 14-16 2003
P6 27QUADOSQUADOS
Results for Task 4 (4/4)
0 2 4 6 8 10 12 14 16 18 20 222.4
2.6
2.8
3.0
3.2
3.4
3.6
3.8
4.0
4.2
4.4
4.6
Flue
nce
x10-6
(par
ticle
s cm
-2)
Moisture (%)
Det.1 Det.2
Participant I Almost all14 participants
providedstochastic
uncertainties.
There waslittle to nonediscussionon other
sources ofuncertainties.
Task 4: Compute the influence ofa change in the water content inconcrete in positions 1 & 2
Environmental ScatterWorkshop in Bologna July 14-16 2003
P6 28QUADOSQUADOS
Generals• ‘Realistic’ neutron spectra• Concept in radiation protection dosimetry• Replicate workplace neutron fields• Enable calibration of area and personal dosimeters in
conditions close to those of their use• Calibration implies :
– Use of reference radiation fields– Knowledge of energy and angle distributions of
fluence—> operational quantities dose equivalent : H*(d) ; Hp(d,a)
Environmental ScatterWorkshop in Bologna July 14-16 2003
P6 29QUADOSQUADOS
Problem 6 : Environmental scatter
• 14 participants + author• Codes :MCNP versions 4B2, 4C, 4C2, 5, X-2.4k,
X-2.5B and Tripoli 4.3• Task 1 : 14 solutions• Task 2 : 8 solutions ( remark 1)• Task 3 : 8 solutions ( remark 2)• Task 4 : 6 solutions
Environmental ScatterWorkshop in Bologna July 14-16 2003
P6 30QUADOSQUADOS
Non-exhaustive list of computational techniquesinvolved in problem 6 (1)
• Task1• Biased isotropic source : SI,SP,SB• Cylindrical shape : EXT,SI,SP• Spectral distribution : ERG,SI,SP• Thermal treatment S(a,ß) in CH2 (shadow cone)
• Thermal treatment S(a,ß) in concrete (~H in H2O)
• Tally F2 (positions 1 & 2) ; disc perp./Ox ; r variable• Tally F4 (positions 1 & 2) ; sphere ; r variable• Tally F5 (positions 1 & 2) ; point detector ; Ro variable• DXTRAN spheres (RIi , ROi) at positions 1 and 2
Environmental ScatterWorkshop in Bologna July 14-16 2003
P6 31QUADOSQUADOS
Non-exhaustive list of computational techniquesinvolved in problem 6 (2)
• Task 2• Tally F1 + Cn cosine card (6 angular bins) reference direction for the cosine binning = normal to the scoring disc surface• Tally F1 + FTn ‘FRV’ (tally special treatment) reference direction for the cosine binning = vector FRV (V1,V2,V3) for a scoring spherical
surface
Environmental ScatterWorkshop in Bologna July 14-16 2003
P6 32QUADOSQUADOS
Non-exhaustive list of computational techniquesinvolved in problem P6 (3)
• Task 3• Cell-flagging : F4 + CFn ‘cell numbers’• Cell-flagging : F5 + FTn ‘ICD’ + FUn ‘cell numbers’
• Task 4• Several ‘task 1 runs’ with different concrete materials• PERTurbation cards with different concrete materials
(only 1 run)
Environmental ScatterWorkshop in Bologna July 14-16 2003
P6 33QUADOSQUADOS
Task 2 : Directional distribution of fluence (1)
• Tally F1 + cosine binning —> Neutron current in thedifferent angular bins crossing disc or sphere surface
• Determination of the neutron fluence in the differentangular bins :- current / (disc surface • mean cosine in angular bin)- current / (sphere surface • 0.5)
• Additional information in T. Mc Lean’s oral
Environmental ScatterWorkshop in Bologna July 14-16 2003
P6 34QUADOSQUADOS
Task 2 : Directional distribution of fluence (2)Position 1
Angular distribution of neutron current at 170 cm
degrees0 20 40 60 80 100 120 140 160 180
Cur
rent
/ co
sine
bin
0
1e-4
2e-4
3e-4
4e-4
5e-4Angular distribution of
neutron fluence at 170 cm
degrees0 20 40 60 80 100 120 140 160 180
Flue
nce
/ cos
ine
bin
0,0
2,0e-7
4,0e-7
6,0e-7
8,0e-7
1,0e-6
1,2e-6
1,4e-6
Environmental ScatterWorkshop in Bologna July 14-16 2003
P6 35QUADOSQUADOS
Task 2 : Directional distribution of fluence (3)Position 2
Angular distribution of neutron current at 300 cm
degrees0 20 40 60 80 100 120 140 160 180
Cur
rent
/ co
sine
bin
0
1e-4
2e-4
3e-4
4e-4
5e-4
Angular distribution of neutron fluence at 300 cm
degrees0 20 40 60 80 100 120 140 160 180
Flue
nce
/ cos
ine
bin
0,0
2,0e-7
4,0e-7
6,0e-7
8,0e-7
1,0e-6
1,2e-6
1,4e-6
Environmental ScatterWorkshop in Bologna July 14-16 2003
P6 36QUADOSQUADOS
Task 2 : Directional distribution of fluence (4)Angular binning ?? = 15°
Angular distribution of neutron current at 170 cm
degrees0 20 40 60 80 100 120 140 160 180
Cur
rent
/ co
sine
bin
0,0
5,0e-5
1,0e-4
1,5e-4
2,0e-4
2,5e-4Angular distribution of
neutron fluence at 170 cm
degrees0 20 40 60 80 100 120 140 160 180
Flue
nce
/ cos
ine
bin
0
2e-7
4e-7
6e-7
Environmental ScatterWorkshop in Bologna July 14-16 2003
P6 37QUADOSQUADOS
Task 2 : Directional distribution of fluence (5)Angular binning ?? = 15°
Angular distribution of neutron current at 300 cm
degrees0 20 40 60 80 100 120 140 160 180
Cur
rent
/ co
sine
bin
0,0
5,0e-5
1,0e-4
1,5e-4
2,0e-4
2,5e-4
Angular distribution of neutron fluence at 300 cm
degrees0 20 40 60 80 100 120 140 160 180
Flue
nce
/ cos
ine
bin
0
2e-7
4e-7
6e-7
Environmental ScatterWorkshop in Bologna July 14-16 2003
P6 38QUADOSQUADOS
Task 3 : Walls- and air-scattering fluence contributions
• 2 approaches were used:
1 - Cell-flagging Additivity should be verified, i. e. : Wall- and air scatter contributions (task 3) should
add up to total fluence (task 1)
2 - ‘Voiding’ technique (M.Králik’s oral)
Environmental ScatterWorkshop in Bologna July 14-16 2003
P6 39QUADOSQUADOS
Task 3 : Walls- and air- scattering fluence contributions (2)
Air- and walls-scattering contributions
airsensors w.
oppos. w.side w. 1
side w. 2 floorceiling
Flue
nce
cont
ribut
ion
by
0,0
2,0e-7
4,0e-7
6,0e-7
8,0e-7
1,0e-6
1,2e-6
1,4e-6
1,6e-6
1,8e-6
at 170 cm
at 300 cm
Environmental ScatterWorkshop in Bologna July 14-16 2003
P6 40QUADOSQUADOS
Oral: Tom McLean
Oral: Miloslav Králik
Environmental ScatterWorkshop in Bologna July 14-16 2003
P6 41QUADOSQUADOS
Summary and Conclusions
The realistic problem attracted 14 participants Task 1: 10 solutions were in good agreement Task 2: 8 solutions Task 3: 8 solutions Task 4: 6 solutions were in good agreement
A wide range of techniques was used Basic differences were seen in computing the
Directional distribution of fluence (Task 2) and Contributions from walls, floor and ceiling (Task 3)
The numerical results wereby in large satisfactory.Several author interpreted theirresults adequately.
The uncertainty associatedwith the results was not *addressed. *Apart from providing stochastic uncertainties.
Environmental ScatterWorkshop in Bologna July 14-16 2003
P6 42QUADOSQUADOS
Appendices
Table of Content
Cell-flagging and ‘Voiding’ techniques (1-4)
The use of calibration fields (1-3)
Environmental ScatterWorkshop in Bologna July 14-16 2003
P6 43QUADOSQUADOS
Cell-flagging and ‘Voiding’ techniques (1)
Geometry 1 Geometry 2
Geometry 3 Geometry 4wall 2 wall 1
Air
Environmental ScatterWorkshop in Bologna July 14-16 2003
P6 44QUADOSQUADOS
Cell-flagging and ‘Voiding’ techniques (2)
Geometry 1 Geometry 2
2 1 2 1
Geometry 2 —> Geometry 1 by voiding wall 1
Geom. 1: CF (air) = 6.40 10-8 = Total
Geom. 2: CF (air) = 8.50 10-8
CF (wall1) = 2.90 10-7 VT (wall1) : 3.75 10-7- 6,40 10-8= 3.11 10-7
Total = 3.75 10-7 Difference CF --> VT : +7.2%
Environmental ScatterWorkshop in Bologna July 14-16 2003
P6 45QUADOSQUADOS
Cell-flagging and ‘Voiding’ techniques (3)Geometry 1 Geometry 3
2 1
Geometry 3 —> Geometry 1 by voiding wall 2
Geom. 1: CF (air) = 6.40 10-8 = Total
Geom. 3: CF (air) = 7.38 10-8
CF (wall1) = 7.45 10-8 VT (wall1) : 1.48 10-7- 6,40 10-8= 8.40 10-8
Total = 1.48 10-7 Difference CF --> VT : +12.7%
2 1
Environmental ScatterWorkshop in Bologna July 14-16 2003
P6 46QUADOSQUADOS
Cell-flagging- and ‘Voiding’ techniques (4)
Geometry 4 —> Geometry 3 by voiding wall 1Geom. 4: CF (air) = 1.01 10-7 Geom. 3: CF(air) = 7.38 10-8
CF (wall1) = 3.31 10-7 CF (wall2) = 7.45 10-8
CF (wall2) = 8.42 10-8 Total = 1.48 10-7
Total = 5.17 10-7 VT (wall1) = 5.17 10-7 – 1.48 10-7= 3.69 10-7
Difference CF VT : +11.5%
Geometry 4
2 1 2 1
Geometry 3
Environmental ScatterWorkshop in Bologna July 14-16 2003
P6 47QUADOSQUADOS
The quantity to be determined is a specific dose equivalent (DE), H, which is computed as theenergy integral over the product of ΦE (E) and the fluence-to-DE conversion factors, hΦ (E).
Let the subscript i=cal indicate the calibration field and i=wp the work place field. Then thecalibration factor, Ncal, is implicitly defined by the requirement: Hcal =: Ncal
.Mcal, and if thecalibrated dosemeter is used in a work place field then one obtains for the difference between thetrue value of the DE in that field to the measured one,
∆=Hwp - Ncal.Mwp,
The last Eqaution lends itself to derive the the design aims of a moderator assembly. One seeclearly, that the choice of the calibration field would be arbitrary, if the energy dependence of hΦis matched by that of RΦ.
The use of calibration fields (1/3)
( ) ( ) )(-)()(-)(d= cal
cal,w,
max
min
ERNEhEEEE
EEpE ΦΦΦΦ∆ ⋅⋅⋅∫
∫ ⋅⋅max
min i,i )( )(d=
E
EE EEhEH ΦΦ ∫ ⋅⋅
max
min i,i )( )(d=
E
EE EEREM ΦΦ
Environmental ScatterWorkshop in Bologna July 14-16 2003
P6 48QUADOSQUADOS
The use of calibration fields (2/2)
10-3 10-2 10-1 100 101 102 103 104 105 106 107 108
Energy (eV)
10-4
10-3
10-2
10-1
Flue
nce
per
uni
t lo
g en
ergy
(Le
thar
gy)
Bare 252Cf without shadow coneBare 252Cf without shadow coneBare 252Cf with shadow coneBare 252Cf with shadow coneMod. 252Cf without shadow coneMod. 252Cf without shadow coneMod. 252Cf with shadow coneMod. 252Cf with shadow cone
10-9 10-8 10-7 10-6 10-5 10-4 10-3 10-2 10-1 100 101
En / MeV
0.1
0.2
0.3
( ΦE
. E )
/ cm
-2
Typ A : <h*Φ(10)> = 12,2 pSv cm2Typ A : <h*Φ(10)> = 12,2 pSv cm2
Typ B : <h*Φ(10)> = 23,9 pSv cm2Typ B : <h*Φ(10)> = 23,9 pSv cm2
Typ C : <h*Φ(10)> = 122 pSv cm2Typ C : <h*Φ(10)> = 122 pSv cm2
Typ D : <h*Φ(10)> = 213 pSv cm2Typ D : <h*Φ(10)> = 213 pSv cm2
Typical neutron spectra in nuclear power plants
10-9 10-8 10-7 10-6 10-5 10-4 10-3 10-2 10-1 100 101
En / MeV
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
( ΦE
. E )
/ cm
-2
252Cf-mod+Schatten : <h*Φ(10)> = 36,0 Sv cm2252Cf-mod+Schatten : <h*Φ(10)> = 36,0 Sv cm2
252Cf- mod + Cd : <h*Φ(10)> = 93,3 Sv cm2252Cf- mod + Cd : <h*Φ(10)> = 93,3 Sv cm2
252Cf : <h*Φ(10)> = 343 Sv cm2252Cf : <h*Φ(10)> = 343 Sv cm2
212Am-Be : <h*Φ(10)> = 381 Sv cm2212Am-Be : <h*Φ(10)> = 381 Sv cm2
"Broad calibration fields"
Environmental ScatterWorkshop in Bologna July 14-16 2003
P6 49QUADOSQUADOS
The use of calibration fields (3/3)
10-3 10-2 10-1 100 101 102 103 104 105 106 107 108
Energy (eV)
100
101
102
103
Res
pons
e pe
r un
it flu
ence
(R
el. u
nits
)
Base (9)Base (9)
Planar (9)Planar (9)
Intermediate (10)Intermediate (10)
Fast (10)Fast (10)
Combination (11)Combination (11)
10-3 10-2 10-1 100 101 102 103 104 105 106 107 108
Energy (eV)
10-3
10-2
10-1
100
101
Res
pons
e pe
r u
nit
fluen
ce (
Rel
. uni
ts)
Eberline_2Eberline_2MODEL 930_2MODEL 930_2LB 6411LB 6411Eberline_3Eberline_3Model 930_3Model 930_3
Personal dosemeters
Survey instruments