During 1987-1999, Mangalore University carried out extensive studies on the baseline radiation levels in the environment of the Kaiga Nuclear Power Station and the West Coast region of India, through three BRNS funded research projects. The highlights of these studies are:
♦ An extensive database was established on the radiation level, and natural and artificial radionuclide concentrations in the terrestrial, aquatic, and atmospheric environmental matrices of Kaiga and the West Coast of India.
♦ The identification of natural plant species, Cymbidium aloifolium (L.), a lichen, and Petrobryopsis tumida (Hook.) Dix., a moss, in the tropical forest of the Kaiga region, as possible bio-indicators for monitoring natural and artificial radioactivity in the environment was made feasible.
Journal of Environmental Radioactivity, Vol. 31, No. 2, pp. 189-198, 1996.

Lichen - Cymbidium aloifolium (L.)

Moss - Petrobryopsis tumida (Hook.) Dix

♦ The presence of ¹³⁷Cs in higher concentrations in the West Coast region of India in general, and around Kaiga region in particular was revealed, well before the nuclear power plant became operational. The reason for this was traced to the significantly higher rainfall, dense forest, higher soil organic matter, and the unique topography of Kaiga. This was considered as a very important finding because in the absence of such studies, and if the studies had been carried after the reactor became operational, the presence of higher ¹³⁷Cs would have been wrongly interpreted as being released from the nuclear power station.
Radiation Physics and Chemistry, UK, Vol. 51, No. 4-6, pp. 623-624, 1998.
Health Physics, USA, Vol. 81, No. 2, pp. 148-155, 2001.
♦ The baseline database generated by the Mangalore University through extensive studies was very useful in the impact assessment of the Kaiga Nuclear Power Station on the environment, and helped in convincing the general public that there is no radiological impact on the environment due to this power plant.

BRNS in the year 2014 sanctioned a Coordinated Research Project (CRP) titled “Standardization of techniques for ¹⁴C and tritium measurements in environmental matrices and evaluation of population doses in the vicinity of PHWR power plant” to CARER. This research project involves a systematic effort on the measurement of ¹⁴C and tritium in the environmental matrices around PHWR plants in India.

The CRP comprises of three projects - Project 1 is aimed at (i) standardizing a method for sampling and measuring of ¹⁴C in the environmental matrices, (ii) estimation of excess ¹⁴C in the environmental matrices, and (iii) establishing a database on population doses around the PHWR power plant in Kaiga. Knowledge on the release rates of ¹⁴C from nuclear facilities is essential because of its long half-life, environmental mobility, and ease of assimilation into living matter. Through this project, methods and standard protocols would be developed for the measurement of ¹⁴C in the environmental matrices, and a reliable data on the release of ¹⁴C from PHWR during normal operations would be generated.

Project 2 of this CRP aims at developing and standardizing methods for (i) long-term continuous sampling of air for tritium measurements, and (ii) measurement of OBT and TFWT in the environmental matrices.

Project 3 aims to (i) establish a calibration centre for radon/thoron measuring devices for the benefit of different research groups of India, (ii) to develop a uniform protocol for measurements of radon/ thoron and progeny, (iii) evolve regional coordinated research projects for the measurements of radon, thoron, and their progenies, and (iv) conduct a large scale study on equilibrium factor distribution and lung dose due to radon, thoron, and their progenies.

The research team of CARER has developed a Thoron Mitigation System in collaboration with the Radiological Physics and Advisory Division (RP & AD), BARC through an MoU. The development of this simple and inexpensive activated charcoal- based mitigation system will find immense application in the continuous removal of radon and thoron from off-gas streams of uranium and thorium processing facilities. Spin-off applications of the newly developed system include remediation of radon and thoron problem in mining and processing industries, site remediation, and reduction of personal radiation exposures. Another potential application is the recovery and isolation of radioactive Xe and Kr fission gases from workplaces.

While the CARER was responsible for the design, fabrication, and characterization of the system, RP & AD, BARC provided the necessary support in the development of the theoretical models and calibration of the system. The characterization experiments resulted in the generation of breakthrough curves, estimation of breakthrough time, adsorption coefficient, degassing characteristics of activated charcoal for radon, and understanding the effect of flow and pressure drop across the bed on the mitigation factor, which are essential for designing a mitigation system for workplaces. A sustained mitigation factor of > 10⁵ was successfully demonstrated for thoron using the thoron mitigation system.

The technology and the prototype system were transferred to BARC and the system has been integrated in to the processing facilities of BARC.

Journal of Environmental Radioactivity,142, 87-95, 2015.

---

Radon breakthrough curves for activated charcoal adsorber beds

Schematic representation of integration of TMS with the thorium processing facility.

CARER has developed a new technique for the measurement of radon concentration in the soil gas. This method makes use of a bubbling system in which the soil gas is drawn through an active pump and bubbled through vegetable oil. After the bubbling process, the oil is subjected to gamma-ray spectrometry. This technique provides an easy approach for the measurement of radon in the soil gas. This was a collaborative work between CARER and the College of Technology, Kuwait.

Journal of Radiation Measurements, Vol. 42, 486 – 490, 2007

Experimental arrangements for soil gas measurement

One of the important studies undertaken by CARER is on the radon absorption efficiencies of different edible oils of plant origin produced in India. This study was performed by bubbling a known concentration of radon through the oil and then, evaluating the bubbled oil by gamma ray spectrometry using an HPGe detector. The results showed that oils such as coconut oil, sesame oil (til oil), groundnut oil, mustard oil, sunflower oil, and saffola kardi oil are very good absorbers of radon, and among them, coconut oil and sesame oil are better absorbers than olive oil. The study also revealed that Henry's equilibrium constants, or the concentration factors, for coconut, sesame, mustard, and sunflower oils are higher when compared to that of olive oil, which was earlier reported as the best radon absorbing oil. These oils are far less expensive when compared to olive oil, and the study showed that they can very well be used for the measurement of radon by using them as an absorbing medium.

Health Physics, 98(4), 621-627, 2010.

India is the second largest producer of rice (Oryza sativa L.) in the world and rice is an essential component of the diet for a majority of the population in India. However, detailed studies aimed at the evaluation of radionuclide transfer factors (F_v) for the rice grown in India are almost non-existent. CARER performed a systematic study on the transfer factors for terrestrial food pathways (such as soil to rice, soil to vegetables, etc.) and concentration ratios for aquatic food chain for natural and artificial radionuclides for field conditions. The salient feature of the study was developing experimental rice and vegetable fields close to the Kaiga nuclear power station using the water drawn from the coolant water discharge canal. For a comparative study, rice and vegetable samples were also collected from the nearby villages. Important findings of this study are:

♦ The ¹³⁷Cs activity concentration in the rice grown using water drawn from the coolant water discharge canal was comparable to those observed in the rice grown by farmers in the nearby villages. This suggested that there was no radiological impact of the nuclear power plant on the main food cultivation of the region,
♦ The radionuclide concentration in the plant did not linearly relate to the soil concentration. The transfer factor values of ⁴⁰K, ²¹⁰Pb, and ¹³⁷Cs for above the ground parts decreased with the increase of activity concentrations of these radionuclides in the soil, which is evidence for non-linearity in the transfer of elements from the soil to above the ground parts of the plants, and
♦ This study generated more than 3000 data regarding transfer factors and concentration ratios for terrestrial and aquatic pathways. BRNS has considered the above project as one of the best research projects.
Journal of Environmental Radioactivity, 118, 80-92, 2013.

CARER has performed extensive studies on the soil to grass transfer factors (F_v) and grass to cow milk transfer coefficient (F_m) for iodine, cesium, and strontium isotopes for equilibrium and emergency situations in the Kaiga nuclear power plant region. This is one of the most comprehensive studies on the F_v and F_mC values for a nuclear power plant in India. For the first time in the country, grass to milk transfer factors for iodine, cesium, and strontium were estimated for emergency situations in field conditions using the experimental grass field and adopted cows. The important findings of the study are:

♦ The F_m values of both ¹³⁷Cs and stable Cs are higher by an order of magnitude for the local breed cows, which are low milk yielding, when compared to the high milk yielding dairy farm cows, and also to the values given in the IAEA publications. The reasons for the higher F_m values for the local breed cows are higher soil ingestion because of extensive grazing, low milk yield rates, negligible supplement feed to the cows, and lower body mass,
♦ The grass to milk transfer of ¹³⁷Cs is influenced by the ⁴⁰K activity concentration in the grass; higher transfer of ¹³⁷Cs occurs when the ⁴⁰K content is lower in the grass,
♦ The mean value of F_m for iodine for equilibrium condition for common grazing areas had a mean value of 8.6x10^-4 d L^-1, which is similar to that reported by IAEA (2010),
♦ The mean value of F_m for emergency situation for iodine was found to be 1.5x10^-3 (d L^-1), which is similar to the value of 5.4x10^-3 (d L^-1) as reported by IAEA (2010),
♦ The mean value of F_m for cesium isotopes for emergency situation was 4.4×10^-3 d L^-1. The strontium F_m values for an emergency situation was found to have a mean value of 1.4×10^-3 d L^-1, and
♦ This study highlighted the need for realistic estimation of F_m values using site specific information on the daily intake of grass and supplement feed by the cows.

Journal of Environmental Radioactivity, 124 (2013) 101-112. Journal of Radiation Protection and Environment, Vol. 34, Issue 3, 210-212, 2012.

experimental grass field,

common grazing areas

The availability of data on the deposition velocity, deposition rate, and mass interception factors for airborne radionuclides is essential for predicting air to grass transfer of radioactivity during an emergency release. This data plays a crucial role in the realistic estimation of doses to the public during an emergency situation. Systematic experiments were carried out by CARER on the air to grass transfer of radioactivity for postulated emergency release. For this, an environmental chamber with a working area of 2 m x 2 m x 2 m was designed, fabricated, and installed, and grass grown in pots were exposed to different concentrations of iodine, caesium, and strontium (stable isotopes of the elements were used). The environmental chamber has facilities to control temperature, humidity, wind flow, simulate rainfall and to expose the plants grown in the pots to controlled levels of radionuclides/stable elements. The studies conducted under various simulated environmental conditions of postulated accidental release, resulted in the following important findings:

♦ The mass interception factor of iodine varied in the range of 0.25-13 m² kg^-1 with a mean value of 4.2 m² kg^-1, when the ambient temperature varied in the range of 20-30°C.
♦ The wet deposition rate and deposition velocity of Iodine was higher by an order of magnitude when compared to the dry deposition rates and deposition velocities. However, the mass interception factors remained nearly the same, both in the case of dry and wet deposition.

Experimental setup using the environmental chamber for studying air to grass transfer of iodine with simulated rainfall

Uranium mineralization has been identified at Gogi, in Yadagiri district of Karnataka, and it is one of the prospective uranium mining regions. CARER has now completed detailed radioecological studies around the proposed uranium mining region, which has resulted in establishing a baseline database for the region. The studies have resulted in some very interesting findings, such as, high concentrations of radon and uranium in some of the tube wells of Gogi village. This is primarily due to the underlying uranium rich geological formations of the region. A digital radiation level map was developed for the Gogi region, which would be of immense benefit in impact assessment around the proposed mining region.

Report on the BRNS research project report titled “Baseline database on radiation level, radionuclides and trace elements concentration in environmental matrices around Gogi”, Mangalore University, 2013.

Recently, CARER completed detailed radioecological studies around the proposed new BARC-RMP campus at Chellekere, Karnataka. Under this study, gamma radiation levels and radionuclide concentrations in the terrestrial, aquatic, and atmospheric environmental matrices were measured and a detailed baseline database was generated. These studies were undertaken under the RMP, BARC-Mangalore University MoU.

BARC, RMP – MoU research project report titled “Detailed radiological studies comprising baseline radiation levels and radionuclide concentrations in environmental matrices in and around Dodda Ullarthi, Challakere”, CARER, Mangalore University, 2016.

CARER has developed an innovative method for instant access to data on radioactivity and related aspects around different facilities. It has developed digital maps for direct access to data on radioactivity around Kaiga, Gogi, and Chellekere regions. These digital maps provide details on radionuclide distribution and gamma dose, GPS coordinates of the sampling locations, etc., by clicking the respective sampling location on the computer. The digital map can be explored using the Adobe Reader on any computer and there is no requirement for additional software. This is considered as a very important contribution of CARER.

Digital radioactivity map of Challakere region (Data on radiation levels and other details are displayed in the right bottom corner)