Mark Julian Henderson

Sorption of plutonium on geological materials associated with a Chinese radioactive waste repository: influence of pH

The aim of this study is to characterize plutonium sorption particularly 239Pu distribution coefficients and the influence of pH on sorption processes in saturated geological materials used as a radioactive waste repository in China. The examined geological media is from a southwestern Chinese repository and consists of soil and slates. The backfill material consists of Na-bentonite from Inner Mongolia Gaomiaozi, and will be used at the Beishan high-level waste (HLW) repository, Gansu Province. The results show that the sorption capacity of Pu by geological medium in an acidic environment is low, but significantly increases with increasing pH.

(Ce-Al)-oxide pillared bentonite: A high affinity sorbent for plutonium

The ability of bentonite and montmorillonite pillared by Al-oxide and mixed (Ln-Al)-oxides (Ln = La, Ce) to remove 239plutonium solution species from water is comparatively investigated at pH 7 and pH 4. Small-angle scattering and neutron contrast variation with H2O/D2O mixtures is used to verify the ingress of water in the calcined products after hydrophilicity was introduced by an NH3-H2O vapor treatment. The size and shape of the (La/Ce)-Al oxo-hydroxy pillaring cations (2 nm spheres) is determined by small-angle x-ray scattering from the pillaring solutions. Not all of the oxide pillars improved Pu uptake compared with sodium montmorillonite. At neutral and acidic pH only (Ce-Al)-oxide pillared clays showed the ability to remove Pu over the concentration range studied (1.35 × 10-8-8 × 10-8 mol dm-3) with distribution coefficient (KD) values >104. XPS analysis of the (Ce-Al)-oxide pillared clays indicates the presence of Ce4+ as cerium dioxide. The progressive improvement in sorption performance in the order of pillar type Al2O3 < La2O3-Al2O3 << CeO2-Al2O3 reflects the increasing access of Pu solution species to the clay mineral layers by changes to the basal spacing and specific surface area, and also to the higher stability of the (Ce-Al)-oxide pillars.

A RAPID SEISMIC DATA CALIBRATION TECHNIQUE USING INTEGRATED MEMS INERTIAL SENSOR GROUPS FOR A THREE-COMPONENT VSP

Calibration of 3C VSP data is an exciting challenge because the orientation of the tool is random when only seismic data is considered. In this work we augment the sensor package on the VSP tool with MEMS inertial sensors and apply a gesture measuring method to determine the tool orientation and calibration. This technique can quickly produce high-precision, orientation and angle information when integrated with the seismometer. The augmented sensor package consists of a low-cost triaxial MEMS gyroscope, an electronic compass and an accelerometer. The technique to process the gesture information is based on the OpenGL software for 3D modeling. We have tested this approach on a large number of field datasets and it appears to be faster and more reliable than other approaches.

A rapid seismic data calibration technique using integrated micro-electro-mechanical system inertial sensor groups for a 3C vertical seismic profileRapid data calibration for 3C VSP

Calibration of 3C VSP data is an exciting challenge because the orientation of the tool is random when only seismic data is considered. In this work we augment the sensor package on the VSP tool with MEMS inertial sensors and apply a gesture measuring method to determine the tool orientation and calibration. This technique can quickly produce high-precision, orientation and angle information when integrated with the seismometer. The augmented sensor package consists of a low-cost triaxial MEMS gyroscope, an electronic compass and an accelerometer. The technique to process the gesture information is based on the OpenGL software for 3D modeling. We have tested this approach on a large number of field datasets and it appears to be faster and more reliable than other approaches.

A rapid seismic data calibration technique using integrated micro-electro-mechanical system inertial sensor groups for a 3C vertical seismic profile

Calibration of 3C VSP data is an exciting challenge because the orientation of the tool is random when only seismic data is considered. In this work we augment the sensor package on the VSP tool with MEMS inertial sensors and apply a gesture measuring method to determine the tool orientation and calibration. This technique can quickly produce high-precision, orientation and angle information when integrated with the seismometer. The augmented sensor package consists of a low-cost triaxial MEMS gyroscope, an electronic compass and an accelerometer. The technique to process the gesture information is based on the OpenGL software for 3D modeling. We have tested this approach on a large number of field datasets and it appears to be faster and more reliable than other approaches.

An improved lossless group compression algorithm for seismic data in SEG-Y and MiniSEED file formats

An improved lossless group compression algorithm is proposed for decreasing the size of SEG-Y files to relieve the enormous burden associated with the transmission and storage of large amounts of seismic exploration data. Because each data point is represented by 4 bytes in SEG-Y files, the file is broken down into 4 subgroups, and the Gini coefficient is employed to analyze the distribution of the overall data and each of the 4 data subgroups within the range [0,255]. The results show that each subgroup comprises characteristic frequency distributions suited to distinct compression algorithms. Therefore, the data of each subgroup was compressed using its best suited algorithm. After comparing the compression ratios obtained for each data subgroup using different algorithms, the Lempel-Ziv-Markov chain algorithm (LZMA) was selected for the compression of the first two subgroups and the Deflate algorithm for the latter two subgroups. The compression ratios and decompression times obtained with the improved algorithm were compared with those obtained with commonly employed compression algorithms for SEG-Y files with different sizes. The experimental results show that the improved algorithm provides a compression ratio of 7580%, which is more effective than compression algorithms presently applied to SEG-Y files. In addition, the proposed algorithm is applied to the miniSEED format used in natural earthquake monitoring, and the results compared with those obtained using the Steim2 compression algorithm, the results again show that the proposed algorithm provides better data compression. An algorithm was proposed to compress losslessly the SEG-Y and miniSEED Files.It describes the distribution of SEG-Y and miniSEED files using Gini coefficient.Different data sub-groups should use different compression algorithms.The improved algorithm can achieve a better compression ratio of 7580%.It provides a better compression ratio than the Steim2 to miniSEED Files.