Rapid calibration of beryllium shims of Nigeria Research Reactor-1

Abstract

In the accident analysis of a typical Miniature Neutron Source Reactor (MNSR), the possibility of a prompt critical accident arising from the addition of the wrong thickness of beryllium shim is usually downplayed. However, this is a real possibility because at some point in the lifetime of any MNSR such as the Nigeria Research Reactor-1 (NIRR-1), beryllium shims will have to be added to compensate for fuel burn-up and poison buildup. Since the operator organization cannot afford to get the thickness required wrong, it is imperative that a simple and reliable means of calibrating the beryllium shims should be developed. Such a scheme has not only been developed but it has been completely automated. It combines the computer codes WIMS and CITATION in an innovative, interactive. Windows environment to carry out the required calibration automatically. It also facilitates rapid recalibration and verification whenever the need arises. It is shown that the scheme results in huge savings in labour and time as well as improved reliability when compared with the traditional manual method of shim calibration.

Nigerian Journal of Physics Vol. 16(2) 2004: 52-57