26.08.2015   ACCELERATOR DRIVEN SUBCRITICAL REACTORS

Neutron yields

The most important experimental observable with respect to hybrid reactors is the number of neutrons produced per proton-nucleus reaction. Recent measurements of neutron multiplicities have been made by Hilscher et al. [110] for thin and thick targets of Pb and U between 1 and 5GeV. Thin target measurements can be compared with those obtained by different INC calculations done in the frame of the OECD workshop [106]. The measurement for thin targets was carried out at 1.22 GeV, while the bench­mark calculations were carried out at 0.8 and 1.6 GeV. In table 6.1 we give a sample of the results of the benchmark and a linear interpolation to 1.22 GeV together with the experimental result. Also present in the last column of the table is a systematics established by Pearlstein [105]. Table

6.1 shows a scatter of close to 30% both on the calculated and measured values.

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Figure 6.4. Comparison of experimental 208Pb neutron induced fission cross-sections with calculations based on the Bertini (left) and ISABEL (right) INC models, with and without pre-equilibrium and using different level densities [90]. Bold dots: data by Vonach et al. [91]. Upper left: Bertini INC, RAL fission, and default level density [101]; solid line: stan­dard MPM; dashed line: no MPM; dotted line: hybrid MPM. Lower left: Bertini INC, RAL fission, and standard MPM: solid line: default level density; dashed line: Julich level density; dotted line: HETC level density. Upper right: ISABEL INC, RAL fission, and default level density; solid line: standard MPM; dashed line: no MPM. Lower right: ISABEL INC, RAL fission, and standard MPM; solid line: default level density; dashed line: Julich level density; dotted line: HETC level density.

Table 6.1. Experimental and computed neutron multiplicities for GeV protons on thin lead targets.

Energy

Experiment

PSI1

LANL2

Dubna3

Jaeri4

BNL5

0.80 GeV

13.6

14.7

12.1

11.46

13.9

1.22 GeV

14.5

16.27

18.00

14.9

13.89

17.31

1.60 GeV

18.7

21.0

17.5

16.10

20.4

1 The PSI calculation was made by F. Atchison and H. U. Wenger. It used the Bertini INC code with the Dresner Evaporation code.

2 The calculation was made by E. Prael with LAHET using the Bertini ICNC, precompound emission and the Dresner EVAP4 evaporation code, with the fission model of Atchison.

3 The calculation was made by Mashnik using the code CEM92M [105] which includes INC + PE + EVAP modules.

4 The calculation was made by T. Nishida et al. and used the Bertini INC + Dresner EVAP.

5 Systematics established by S. Pearlstein.

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