[en] Defence vehicles like battle tanks, Infantry Combat Vehicle (ICV) and other tracked vehicles can operate in areas affected by hazardous radionuclide due to a nuclear disaster. Collective protection system is employed in such vehicles which consist of Initial Nuclear Radiation (INR) sensors, gamma radiation monitors, Nuclear Biological and Chemical (NBC) filters, sealing and overpressure system, various activation and control mechanisms for the air handling and other mechanical sub systems. The INR sensors detect the prompt INR pulse and activate the automatic NBC system and provide protection from the blast waves. The gamma radiation monitors measures the radiation levels in the contaminated area. The various sub-systems of NBC protection system operate in a definite sequence to provide the required protection of crew and equipment of the defence vehicles. Reliable operation of the protection system in the harsh environment of the defence vehicles, which operate in the extremes of climate, mechanical stress, and electromagnetic environment, is most essential. (author)

[en] Semi-automatic gamma radiation test and calibration facility have been designed, developed and commissioned at Defence Laboratory Jodhpur (DLJ). The facility comprises of medium and high dose rate range setup using 30 Ci Cobalt-60 source, in a portable remotely operated Techops camera and a 15000 Ci ⁶⁰Co source in a Tele-therapy machine. The radiation instruments can be positioned at any desired position using a computer controlled positioner having three translational and one rotational motion. User friendly software helps in positioning the Device Under Test (DUT) at any desired dose rate or distance and acquire the data automatically. The servo and stepper motor controlled positioner helps in achieving the required precision and accuracy for the radiation calibration of the instruments. This paper describes the semi-automatic radiation test and calibration facility commissioned at DLJ. (author)

[en] Semi-automatic gamma radiation test and calibration facility have been designed, developed and commissioned at Defence Laboratory Jodhpur (DLJ). The facility comprises of medium and high dose rate range setup using 30 Ci Cobalt-60 source, in a portable remotely operated Techops camera and a 15000 Ci ⁶⁰Co source in a Tele-therapy machine. The radiation instruments can be positioned at any desired position using a computer controlled positioner having three translational and one rotational motion. User friendly software helps in positioning the Device Under Test (DUT) at any desired dose rate or distance and acquire the data automatically. The servo and stepper motor controlled positioner helps in achieving the required precision and accuracy for the radiation calibration of the instruments. This paper describes the semi-automatic radiation test and calibration facility commissioned at DLJ. (author)

[en] The PIN detectors when operated with reverse bias in the pulse mode offer a large volume of depletion region, which act as an efficient detection medium for the ionizing radiations. The detector reverse bias and the temperature effect the output counts per second (CPS) for a given radiation intensity. A detailed investigation carried out on these effects for 1 mm² Si PIN diode is being reported in this paper. The studies carried out facilitate in the optimisation of detector bias and operating temperature for its improved performance in dosimetry applications. It is observed that a bias of 160 V is an optimum choice for 1 mm² devices, which cover the dose rate ranging from 50 mR/h to 1000 R/h. It is also observed that the effect of temperature on output counts is negligible up to a certain limit (∼ 60 degC for lesser leakage current diodes) but beyond that the counts decrease abruptly. (author)

[en] A semiconductor based compact device, 'Gamma Flash Sensor' has been developed for detection of pulse gamma ray of the intensities of the order of 4 R/s. The semiconductor sensing element is used in photovoltaic mode to produce a voltage proportional to the intensities of pulsed gamma rays. The signal after processing and threshold comparison produces an output activation signal when the gamma dose rate exceeds 4 R/s. This compact device has application for the automatic activation of Nuclear, Biological and Chemical (NBC) protection system in Defence vehicles and underground NBC shelters. (author)

[en] The DEfence Laboratory RAdiation Detector - 'DELRAD' is an indigenously developed Hybrid Micro Circuit Module employing Si PIN diodes for detection of gamma radiation. Using this as a detector, the 'DELRAD Probe' has been designed and developed specifically for the UAV, NETRA for aerial surveillance of the nuclear affected areas. The critical requirement of very light weight radiation sensor as payload (<50gm) for the UAV NETRA is met by designing this Probe weighing approx. 40gm. The sensor is capable of measuring gamma radiation levels from 1mR/h to 1000R/h. The Probe has been tested, calibrated and integrated with the UAV NETRA. In addition to this, the radiation testing during flight of UAV NETRA integrated with DELRAD probe has also been carried out and results have been recorded. The work carried out proves the capability of Defence Laboratory, Jodhpur, (DRDO) in the area of 'Aerial Surveillance of Nuclear Radiation Affected Area' using Unmanned Aerial Vehicles (UAVs)

[en] Due to increased uses of radio-isotopes in almost all the fields like: research and development, medical diagnostics and treatment, nuclear power generation, nuclear weapons and industry it has become essential to carryout 24 x 7 gamma radiation monitoring at and around the sites employing nuclear radioactive sources. Also, radiation monitoring at nuclear contaminated distant and remote sites where regular visits are not feasible and manual monitoring not recommended due to radiation health hazards, to be carried out to estimate the radiation exposure to the people in near vicinity. Now, the monitoring if done remotely, the radiation exposure to the monitoring team can be avoided. The RRMTS has been developed for 24 x 7 gamma radiation at multiple remote locations. It is capable of measuring gamma radiation levels over a very wide range from background (μR/h) to 1000R/h making it suitable for environmental radiation monitoring as well as radiation monitoring during nuclear emergencies

[en] The X-ray mass attenuation coefficient of Nb compound around the k-edge is measured in the energy range 18.913 keV to 19.688 keV and the technique used for this measurement of (μ/ρ) is the scanning EXAFS synchrotron radiation source, at Raja Ramanna Centre for Advanced Technology (RRCAT), Indore, India. The obtained results are in consistent with the theoretical calculated ones. (author)

[en] Batch sorption experiments were carried out under aerobic conditions to understand the sorption behavior of U(VI) onto bentonite clay under varying pH (2-8) and ionic strength (I = 0.01 - 1 M (NaClO₄)) conditions. The influences of different complexing anions (1 x 10^-4 M) such as oxalic acid (ox), carbonate (CO₃^2-), citric acid (cit), and humic acid (HA, 10 mg/L) on the sorption behavior were also investigated. The sorption of U(VI) increased with increasing pH up to pH 6 beyond which a decrease was attributed to the formation of anionic carbonate species. Marginal influence of the change in the ionic strength of the medium on the sorption profile of uranium suggested inner-sphere complexation onto the bentonite surface. The presence of humic acid showed interesting sorption profile with varying pH. Initially, there was an enhancement in the sorption with increased pH followed by a plateau and finally a decrease thereafter due to the formation of aqueous U(VI)-humate complexes. Spectroscopic studies such as UV spectrophotometry, luminescence and extended X-ray absorption fine structure (EXAFS) measurements were also performed to understand the changes in aqueous speciation of U(VI) ion. The luminescence yields of different aqueous U(VI) species followed the order: U(VI)_Hydroxy > U(VI)_HumicAcid > U(VI)_carbonate > U(VI)_citrate. The lower luminescence yield of U(VI)carbonate complex can be attributed to the strong dynamic quenching by carbonate at room temperature. The U(VI) samples shows two distinct life-time suggesting the presence of the different luminescent U(VI) species. Similar trend was observed for U(VI)-bentonite suspension in presence/absence of the complexing ligands. There was luminescence quenching for the sorbed U(VI) due to surface complexation. These observations were further supported by spectrophotometric measurements. EXAFS spectra of U(VI) samples were recorded in luminescence mode at the U L₃ edge. There was shift in the absorbance edge which was attributed to decrease in electron density at U(VI) due to surface or ligand complexation. The R space spectra are mainly dominated by the back-scattering from the axial oxygens in the first shell. The inner-sphere multinuclear complex formation takes place during the U(VI) sorption onto bentonite.

[en] In present research work, Prunus armeniaca L. (Wild Apricot) Seed oil has been investigated to produce biodiesel. The free fatty acid (FFA) content of the Prunus armeniaca oil (PAO) was <2%, so a single stage alkali catalyzed transesterification process was used to produce Prunus armeniaca methyl ester (PAME). The transesterification was conducted using optimum condition of 1% (w/w) potassium hydroxide as catalyst, 55 °C reaction temperature and 60 min reaction time with constant stirring at 400 rpm. Transesterification process gave a maximum yield of 96.5% by weight of Prunus armeniaca biodiesel. Fuel properties determined in the study conform to standards set for the ASTM D6751 and EN 14214. PAME exhibited a satisfying oxidative stability of 6.3 h and high cetane number (58.7) compared to petrodiesel (49.7). The experiments were conducted using various blends (B5, B10, B20 and B30) of the methyl ester of PAO with diesel in a single cylinder, four strokes, and direct injection diesel engine. The test results show that the brake thermal efficiency (BTE), in general, was found to be decreased and brake specific fuel consumption (BSFC) increased with increased volume fraction of P. armeniaca biodiesel (PAME) in the blends. A marginally higher BTE and lower BSFC noticed for B5 blend than diesel. At higher load conditions, CO, UHC and smoke opacity were found lower for all PAME blends in comparison to neat diesel. The NOx emissions were found to be increased for PAME based fuel in comparison to neat diesel. It may be concluded from the experimental investigations that PAME, can be an alternative for petrodiesel that can be used in a diesel engine without any major modification in the engine.