Abstract
The results of criticality, sensitivity and uncertainty (S\U) analyses on the first core criticality of the Indonesian 30 MWth Multipurpose Reactor RSG GAS (MPR-30) using the recent nuclear data libraries (ENDF/B-VII.1 and JENDL-4.0) and analytical tools available at present (WHISPER-1.1) are presented. Two groups of criticality benchmark cases were carefully selected from the experiments conducted during the first criticality approach and control rod calibrations. The C/E values of effective neutron multiplication factor (k) for the worst case was found around 1.005. Large negative sensitivities were found in (n,e-mail:γ) reaction of H-1, U-235, Al-27, U-238 and Be-9 while large positive sensitivities were found in U-235 (total nu and fission), H-1 (elastic), Be-9 (free gas, elastic) and H-1 S(α,β) (lwtr.20t, inelastic). The S\U analysis results concluded that the uncertainties of k originated from the nuclear data were found around 0.6% which covered well the [C/E-1] values. Differences in the sensitivities amongst the two nuclear data libraries were also identified, and recommendation for improving the nuclear data library was given.
Highlights
With the growing computing speed, the Monte Carlo method has been widely adopted in the reactor physics simulation including the neutronics benchmark calculation of Indonesian Multipurpose Research Reactor Reaktor Serba Guna G.A. Siwabessy (RSG GAS) in order to evaluate the effective neutron multiplication factor k [1], control rod worth, power distribution, and kinetics parameters [2]
Reactivity gains were measured by calibrating the difference of the regulating rod (RR) position with a reactivity meter and it had been corrected by a method described elsewhere [1]
The sensitivity coefficients in this study have been calculated by MCNP6.2 using 10,000 neutron histories and 10,000 neutron generations with 100 inactive ones
Summary
With the growing computing speed, the Monte Carlo method has been widely adopted in the reactor physics simulation including the neutronics benchmark calculation of Indonesian Multipurpose Research Reactor RSG GAS in order to evaluate the effective neutron multiplication factor k [1], control rod worth, power distribution, and kinetics parameters [2]. Many Monte Carlo codes such as McCARD [3], MCNP6.2 [4] and Serpent2 [5] have the capability to calculate the sensitivity coefficient (S ) of k to each isotope for each neutron reaction at each energy group. Later, using S and the covariance data from the nuclear data library, the uncertainty (U) of k to the nuclear data library can be calculated. The sensitivity and uncertainty (S\U) analyses on the first core criticality of the Indonesian Multipurpose Research Reactor RSG GAS are evaluated using the modern nuclear data libraries such as ENDF/BVII.1 [6] and JENDL-4.0 [7] using Whisper-1.1 [8] within MCNP6.2 software distribution
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