International Reactor Dosimetry File 2002 - IAEA Publications

Table 7.3 details the 34 dosimetry reactions and their cover combinations
that were measured in support of the SPR-III spectrum characterization.
MCNP calculations were undertaken to determine an a priori neutron
spectrum to be used in the spectrum adjustment [7.14]. Models used in these
calculations were validated by a series of reactor worth measurements reported
in Ref. [7.5]. The SAND-II [7.15] iterative spectrum unfold code was used to
produce the baseline spectrum [7.10]. A Monte Carlo based iterative
application of the SAND methodology was used to produce a neutron
spectrum uncertainty and covariance matrix. The Monte Carlo simulations
sampled from a statistically valid representation of the foil activities and the
input trial spectrum. An LSL spectrum adjustment was also performed for this
spectrum.
TABLE 7.3. SPECTRUM AVERAGED DOSIMETRY CROSS-SECTIONS
FOR THE SPR-III CENTRAL CAVITY
Reaction
number
Sensor reaction
Foil
to
cover a Activity Δσ cnt C/E Δσ score C/E
calculated
(Bq/nucleus) (%) ratio (%) ratio
deviation
Measured MCNP calculated SAND-II unfold
Measured
(%)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
197 Au(n,γ) 198 Au Cd 6.574E-18 4.5 0.7428 1.16 1.0269 –2.621
197 Au(n,γ) 198 Au 7.414E-18 4.5 0.6931 1.12 0.9766 2.410
59 Co(n,γ) 60 Co Cd 6.923E-22 2.9 0.5928 1.69 0.9747 2.568
63 Cu(n,γ) 64 Cu Cd 3.302E-18 2.2 0.8776 0.13 1.0266 –2.585
115 In(n,n′) 115 In m 6.204E-17 4.7 1.1280 0.14 0.9766 2.350
nat Ti(n,x) 46 Sc Cd 7.325E-21 3.4 0.9416 0.62 0.9524 5.009
nat Ti(n,p) 47 Sc Cd 2.882E-19 2.7 1.1590 0.27 1.0673 –6.314
48 Ti(n,p) 48 Sc Cd 8.684E-21 1.2 0.9456 1.43 0.9443 5.869
32 S(n,p) 32 P 2.508E-19 3.0 1.0746 0.31 1.0050 –0.486
58 Ni(n,p) 58 Co Cd 8.752E-20 3.1 1.0311 0.26 0.9662 3.462
54 Fe(n,p) 54 Mn Cd 1.400E-20 3.2 1.0893 0.33 1.0331 –3.197
56 Fe(n,p) 56 Mn Cd 5.408E-19 2.4 0.9791 1.10 1.0097 –0.956
64 Zn(n,p) 64 Cu Cd 3.882E-18 2.2 1.1090 0.27 1.0452 –4.323
24 Mg(n,p) 24 Na Cd 1.242E-19 3.0 1.1055 1.48 1.0648 –6.086
27 Al(n,α) 24 Na Cd 6.135E-20 1.9 1.0386 1.63 0.9940 0.561
81