Methodology and algorithm to correct the thermal neutron porosity for the effect of rare elements and rock minerals with high neutron absorption probability

The thermal neutron porosity is routinely acquired in almost every well. When combined with the density, gamma ray and resistivity logs, the basic petrophysical parameters of a reservoir are evaluated. The design of the thermal neutron tool is simple, but its interpretation is complex and affected by the formation constituents. The most challenging situation occurs when the formation contains elements with high absorption probability of the thermal neutrons. The existence of such elements changes the neutron transport parameters and results in a false increase in the measured porosity. The problem is reported by many users throughout the years. In 1993, higher thermal neutron porosity is reported due to the existence of an iron-rich mineral, Siderite, in the Nazzazat and Baharia formations in Egypt. Siderite and all iron-rich minerals have high thermal neutrons absorption probability. Recently, in 2018, high thermal neutron porosity in Unayzah field in Saudi Arabia is also reported due to the existence of few parts per million of gadolinium. Gadolinium is a rare element that has high probability of thermal neutron absorption. Currently, none of the existing commercial petrophysics software(s) have modules to correct the thermal neutron porosity for such effects. This represents a challenge to the petrophysicists to properly calculate the actual reservoir porosity. In this paper, the effects of the rare elements and other minerals with high thermal neutron absorption probability on the thermal neutron porosity are discussed, and a correction methodology is developed and tested. The methodology is based on integrating the tool design and the physics of the neutron transport to perform the correction. The details of the correction steps and the correction algorithm are included, tested and applied in two fields.

Short.Term Reactivity Change: Xenon Effects

Most fission products absorb neutrons to some extent and they accumulate slowly as the fuel burnup increases, hence decrease the long-term reactivity. The neutron-absorbing fission-product xenon-135 has particular operational importance. Its concentrations can change quickly in a power maneuvre, producing major changes in neutron absorption on a relatively short-time scale (minutes).

A Short Critique on Development and Properties of B4C Dispersed Epoxy and Rubber Based Irradiation Shielding Materials

The present article deals with the review on the development and the after effect of irradiation exposure on the properties and characteristics of some B4C polymeric irradiation shielding materials. The smorgasbord of radiations such as alpha, beta, neutron and gamma and their effects not only on biotic but also on a-biotic environments lead to the development of irradiation shielding materials. This article confirms the fabrication of shielding materials that trades off the factor weight without compensating the irradiation shielding ability however possibly by studying material with high thermal neutron absorption and other attenuation factors. One such material is polymers and its allied materials owing to the presence of rich in hydrogen content and the tendency to augment particles within themselves made them suitable for the above mentioned purpose. The details of fabrication and the effects on the mechanical properties are well discussed in this work

Novel α + β Zr Alloys with Enhanced Strength

Low-alloyed zirconium alloys are widely used in nuclear applications due to their low neutron absorption cross-section. These alloys, however, suffer from limited strength. Well-established guidelines for the development of Ti alloys were applied to design new two-phase ternary Zr alloys with improved mechanical properties. Zr-4Sn-4Nb and Zr-8Sn-4Nb alloys have been manufactured by vacuum arc melting, thermo-mechanically processed by annealing, forging, and aging to various microstructural conditions and thoroughly characterized. Detailed Scanning electron microscopy (SEM) analysis showed that the microstructural response of the alloys is rather similar to alpha + beta Ti alloys. Duplex microstructure containing primary alpha phase particles surrounded by lamellar alpha + beta microstructure can be achieved by thermal processing. Mechanical properties strongly depend on the previous treatment. Ultimate tensile strength exceeding 700 MPa was achieved exceeding the strength of commercial Zr alloys for nuclear applications by more than 50%. Such an improvement in strength more than compensates for the increased neutron absorption cross-section. This study aims to exploit the potential of alpha + beta Zr alloys for nuclear applications.

Neutron Diffraction Study on the Magnetic Structure of 153EuMnO3-δ: One Way to Assess the Magnetic Structure of EuMnO3-δ

Owing to the strong neutron absorption of 151Eu, 151Eu free 153EuMnO3-δ has been synthesized to collect the neutron diffraction data for analyzing the magnetic structure of EuMnO3-δ. The obtained neutron diffraction data of 153EuMnO3-δ indicates that the magnetic diffraction peaks corresponding to cAAFM (canted A-type antiferromagnetic) phase can be observed, but the magnetic diffraction peaks corresponding to expected ICAFM (incommensurate antiferromagnetic) phase may be too weak to be observed.