29th Symposium on Fusion Technology (SOFT 2016)

P3.176 Benchmark experiment on copper with graphite by using DT neutrons at JAEA/FNS

7 Sep 2016, 11:00

1h 20m

Foyer 2A (2nd floor), 3A (3rd floor) (Prague Congress Centre)

Board: 176

Poster I. Materials Technology P3 Poster session

Speaker

Saerom Kwon (Japan Atomic Energy Agency)

Description

In our previous copper benchmark experiment we had pointed out that the elastic scattering and capture reaction data of the copper had included some problems in the resonance region, which had caused a large underestimation of reaction rates of non-threshold reactions. In order to corroborate this issue, we carried out a new benchmark experiment on copper in the neutron field with more low energy neutrons. The experimental assembly consisted of quasi-cylindrical copper (63.0 cm diameter, 60.8 cm thick) with graphite blocks (63.0 cm diameter, 10.1 cm thick) in the front part of the copper. Also, the side and rear parts of the assembly were covered with Li2O blocks (5.1 cm, 15.3 cm thick) to absorb background neutrons. We measured reaction rates, ⁹³93Nb(n,2n)^92m92mNb, ²⁷27Al(n,α)²⁴24Na, ¹¹⁵115In(n,n')^115m115mIn, ¹⁹⁷197Au(n,γ)¹⁹⁸198Au and ¹⁸⁶186W(n,γ)¹⁸⁷187W, using the activation foils. We analyzed the experiment with MCNP-5.140 and the latest nuclear data libraries, ENDF/B-VII.1, JEFF-3.2 and JENDL-4.0. As a result, the calculated reaction rates related to low energy neutrons, ¹⁹⁷197Au(n,γ)¹⁹⁸198Au and ¹⁸⁶186W(n,γ)¹⁸⁷187W, excessively underestimated the measured ones as in the previous benchmark experiment. We also tested the nuclear data of copper modified in the previous study, where the elastic scattering cross section of copper was increased by 10 % and the capture reaction of copper was decreased by 10 % from 100 eV to 300 keV. Then the calculated reaction rates with the modified copper nuclear data reproduced the measured ones well. It was revealed that the modification of the specific cross sections had been sufficient in the neutron field with more low energy neutrons. The cross section data of the elastic scattering and (or) capture reaction of copper should be reevaluated.