Physical and Earth Science Research Laboratory

डा. बुद्धराम शाह

मुख्य वैज्ञानिक अधिकृत

प्रमुख, Physical and Earth Science Research Laboratory

Physical and Earth Science Research Laboratory
प्रमुख	डा. बुद्धराम शाह , मुख्य वैज्ञानिक अधिकृत
इमेल	[email protected]
महाशाखा	विज्ञान संकाय

Background

The Physical Science Research Laboratory conducts research primarily in the fields of radiation science and nanomaterials. Radiation research encompasses both ionizing radiation and selected areas of non-ionizing radiation, including radiofrequency radiation. The laboratory's flagship activity is the provision of occupational radiation dosimetry services to radiation workers, particularly those employed in public and private healthcare institutions across Nepal.

In addition to occupational radiation protection, the laboratory undertakes environmental radioactivity monitoring, including measurements of background gamma radiation and indoor radon concentrations. The nanomaterials research program focuses on the synthesis, characterization, and application of advanced nanomaterials for scientific and technological innovation.

Personal Dosimetry Service

The Personal Dosimetry Service is the laboratory's core radiation protection program. Currently, more than 1,200 radiation professionals from over 100 hospitals and institutions throughout Nepal are monitored on a three-month cycle for occupational radiation exposure using Thermoluminescent Dosimeters (TLDs).

The dosimetry system employs lithium fluoride (LiF:Mg,Ti) thermoluminescent phosphors in the form of TLD cards. Each radiation worker wears a TLD badge during working hours for a period of three months. At the end of each monitoring cycle, the badges are collected for dose assessment, and a new set of TLDs is issued to ensure continuous monitoring.

The laboratory established Nepal's first national occupational dosimetry service in 2016 and maintains a comprehensive dose registry under its Quality Management System (QMS). Calibration and quality assurance of the TLD reader are regularly maintained in collaboration with the Secondary Standard Dosimetry Laboratory (SSDL) of the International Atomic Energy Agency (IAEA) and the Nuclear Agency Malaysia, ensuring measurement traceability and reliability.

The development and strengthening of the dosimetry service were significantly supported through the IAEA Technical Cooperation Project NEP9005, Strengthening Radiation Safety through Regulatory Infrastructure, Occupational and Medical Exposure Control (2018–2021).

Environmental Radioactivity Measurement

The laboratory conducts environmental radioactivity assessments to establish baseline radiation levels and evaluate public exposure from naturally occurring radionuclides.

Gamma-ray spectrometric analyses are performed on environmental samples collected from different provinces of Nepal to determine radionuclides belonging to the uranium (²³⁸U), thorium (²³²Th), and potassium (⁴⁰K) decay series. Measurements are carried out using a 14-pin digiBASE gamma-ray spectrometry system coupled with a 3” × 3” NaI(Tl) scintillation detector.

The laboratory also performs nationwide indoor radon surveys using passive radon dosimeters (LR-115 and CR-39) based on Solid State Nuclear Track Detector (SSNTD) technology. These studies contribute to the assessment of radon exposure in residential and occupational environments. Notably, radon monitoring has been conducted in earthquake-affected areas of Sindhupalchok and Gorkha districts following the 2015 Gorkha earthquake to evaluate potential changes in indoor radon concentrations associated with geological disturbances.

Nanomaterials Research

The synthesis, characterization, and application of metal oxide nanostructures are the main areas of interest for nanomaterial research. Many metal oxides are crucial due to their wide range of electronic and optical properties. Appropriate doping processes can further alter these properties. In this project, nanomaterials made from metal oxides are synthesized by the wet chemical route (sol-gel, hydrothermal, microwave, spin coating, etc.). Their crystalline properties are examined by an X-ray diffractometer. The optical properties are determined using UV-visible spectroscopy. Different modes of vibration/stretching of molecular bonding and functional groups of the synthesized samples were detected using Raman and FTIR spectroscopy. The electrical properties are measured between room and high temperatures using the four-probe method. The effective electric charge of particles in suspension is determined by zeta potential. And the samples are sent elsewhere for morphological studies using field emission scanning electron microscopy (FESEM), high-resolution transmission microscopy (HRTEM), Brunauer-Emmett-Teller (BET) surface area analysis, and atomic force microscopy (AFM). We have been dealing with nanomaterial for many applications, such as in wastewater treatment (photocatalytic and adsorption kinetics), gas sensors, dye-sensitized solar cells (DSSCs), biomedical applications, etc.

Earth Science Research

The geological science research activity focuses on a wide spectrum of the earthquake science, from studies of an individual earthquake to tectonic geomorphology. The research combines information from satellite imagery, field observations, tectonic and seismicity database to understand the earthquake genesis in process in the Nepal Himalaya. Accelerometers are being installed which will help to better understand the local site effects and to lay foundation for establishment of earthquake early warning in the country. The works also tries to increase public awareness about an earthquake.

SSDL Project (IAEA NEP6004)

At present, Nepal lacks a calibration for radiation measurement devices. As a result, Nepal is dependent on foreign countries for this purpose. It is therefore imperative to strengthen the capability of NAST in performing the calibration of devices being used in the country for which we need a secondary standard level setup.

A project (NEP6004) on Establishing Secondary Standard Dosimetry Laboratory (SSDL) has been approved for Nepal by the International Atomic Energy Agency (IAEA) of which NAST is the main Counterpart. Under this project, to perform the calibration work, a Bunker has been constructed to install 20 Ci: Cs-137 radioactive sources. This radioactive source will be provided by the IAEA and building a Bunker is under the responsibility of Nepal Government. The architectural and Engineering Design, Cost Estimate and Bidding Document of the Bunker Building having Bunker Component underground (two mirror irradiation rooms) and an office building on the ground floor have been completed. The Bunker building is ready to handover for initiating its activities upon installations of required irradiators.

Team Members

1. Dr. Buddha Ram Shah ([email protected]/ [email protected])

2. Dr. Deependra Das Mulmi ([email protected]/ [email protected])

3. Dr. Dilli Ram Thapa ([email protected] , [email protected])

4. Dr. Shiba Subedi ([email protected])

3. Mr. Bishnu Neupane ([email protected] / [email protected]))

4. Mr. Ram Sharan Karki ([email protected])

5. Mr. Pramod Subedi ([email protected]; [email protected])

6. Mr. Deepak Deuja ([email protected])