The impact of human activities on the sediments of Manila Bay was evaluated through elemental analysis to determine the trace metal element concentration and calculate the corresponding metal enrichment factor (EF). The samples were analyzed using the X-ray tube-excited XRF (X-ray fluorescence) with Ag secondary target to quantify elements Mn to Pb, while the Fe target was used to quantify elements Na to Cr. The radioisotope-excited XRF with 241Am was used for Cd and Hg. The normalized EF has been calculated against baseline values to estimate the environmental impacts of human activity on the bay. In an attempt to provide a better understanding of sediment movement and reworking in the bay, spatial distribution of metals was correlated with the obtained 210Pb radioactivity levels in Manila Bay sediments. Overall, heavy metal and other trace elements are low in Manila Bay sediments, mostly ranging from deficient or minimal to moderate enrichment except for some stations where enrichment of Mn and Cu is significant. Nevertheless, there is a need to estimate the enrichment levels in marine sediments to effectively understand the risk and impact of heavy metals to support management and decision making for the rehabilitation, protection, and maintenance of a healthy ecosystem along the bay.

The Philippine Research Reactor-1 (PRR-1) will be revived as a subcritical assembly for training, education, and research (SATER) in the field of nuclear science and technology. SATER will utilize the existing slightly irradiated nuclear fuel rods that have been maintained in the PRR-1 facility for more than 30 years. A subcritical arrangement for the fuel rods was chosen considering the inherent safety of this configuration. In this paper, we calculate relevant reactor parameters that characterize different annular and hexagonal subcritical configurations of 44 PRR-1 fuel rods. These parameters include the neutron multiplication factor ( ), the effective delayed neutron fraction ( ), and the mean neutron generation time ( ), which are essential quantities to describe reactor behavior. Calculations were performed using the well-validated Monte Carlo radiation transport code MCNP5 v.1.6 together with the ENDF/B- VII.1 evaluated nuclear data library. The maximum value is at 4.0 cm pitch for the chosen annular arrangement, while the maximum value is at 4.3 cm pitch for the chosen hexagonal arrangement. For these configurations, the reactor kinetic parameters were and for the annular arrangement, while and for the hexagonal arrangement. Results demonstrate that with 44 fuel rods, different fuel arrangements remain subcritical with a subcriticality margin that is at least or maximum of 0.97. The key reactor performance characteristics determined in this study can aid in the analysis of transient behavior and safety assessment of subcritical core configurations with TRIGA fuel rods. Our results provide support in expanding the utilization options for irradiated TRIGA fuel rods, even for other TRIGA facilities

The Philippine Research Reactor-1 (PRR-1) fuel storage facility is a wet storage for irradiated nuclear fuel. The behavior of the facility in case of accidental loss of water is currently unknown. Safety analysis of a repository of fissile material involves criticality safety assessment and radiation dose estimation for normal and accident scenarios. To determine the radiological consequences of loss of water inventory in the fuel storage facility, we calculated the effective multiplication factor (keff) and gamma dose rate distribution in the system using Monte Carlo N-particle (MCNP) radiation transport code. Results show that keff will decrease from a maximum of 0.61424 ± 0.00013 when the water level is decreased from its fully moderated condition. In contrast, keff will increase to a maximum of 0.7468 ± 0.0002 when voids are introduced in the water. These results indicate that the system will remain subcritical (keff<1) and a runaway supercritical fission chain reaction cannot result from any moderating conditions. Furthermore, the dose assessment for the case of complete loss of water revealed a maximum dose rate of 5.52 ± 0.045 mSv/h and 288 ± 4.65 𝛍Sv/h at the tank surface and tank platform, respectively. These values are significantly above background radiation levels; however, the calculated spatial distribution is highly asymmetric and the dose rate falls off rapidly with increasing distance. These results suggest that a facility-level emergency response is sufficient to address the accident. Our findings can augment the existing facility emergency procedures, thereby contributing to the improvement of radiological safety.

For the past three decades, the Philippines’ expertise in nuclear science and technology (S&T) has diminished resulting from the shutdown of the Philippine Research Reactor-1 (PRR-1) in the 1980s. In addition, the mothballed Bataan Nuclear Power Plant (BNPP) and the low confidence in nuclear technologies led to the non-prioritization of nuclear science in the country. Consequently, new nuclear facilities were never re-introduced, and the transfer of knowledge declined and nuclear applications were limited to radiation and isotopic studies. If the current initiatives of the Philippines in the use of nuclear energy will push through, the country will need competent human resources who will be responsible for building the nuclear facilities and their safe operation. To augment the declined nuclear expertise in the country, the DOST-PNRI implemented capacity building activities to reestablish and sustain knowledge and expertise in nuclear S&T in the country. Activities that were implemented include the development of training materials for undergraduate students and the development of research facility using isotopic neutron sources. This paper discusses the capacity building strategies implemented and their significant outputs, as well as plans for sustainability and continual development.

Allanite is one of the most common sources of rare-earth elements (REEs) and contains significant amounts of thorium (Th) and uranium (U). The presence of radioactive Th and U nuclides in the mineral exposes it to long-term radiation. Like other natural minerals containing Th and U, allanite can be used as a natural analog to understand the long-term radiation effects in high-level nuclear waste (HLW) matrices. Allanite group mineral is generally found in the amorphous phase due to structural damage induced by self-irradiation. In this work, crystalline allanite-(La) samples collected in San Vicente, Palawan, Philippines – having a low absorbed -dose of ~ 1014 α-decays/ mg – were heated at 450, 650, and 850 °C to study the response of non-metamict allanite to heating at elevated temperatures, particularly at the early stages of exposure to alpha-particle radiation. An increase in structural order was observed upon heating to 450 and 650 °C, which is exhibited by a decrease in the unit cell volume by 1.6% and a decrease of the full width at half maximum (FWHM) of selected Bragg planes. It was evident that certain Bragg planes respond differently to the annealing temperatures with preferential reorientation. After annealing at 850 °C, however, the loss of OH bonds was observed in the infrared (IR) spectra, and the broadening of Bragg peaks was seen in the x-ray diffraction (XRD) patterns, suggesting an onset of structural degradation. Surface cracks are also seen in the scanning electron microscope (SEM) images. The study shows that the non-metamict allanite-(La) mineral structure responds to heating similarly to that of metamict ones reported in the literature. This study will provide data on the properties of allanite as part of the ongoing studies on radiation damage in silicate matrices.