WHO report is sighted in Indian News Papers show that out of 57 million global deaths in 2008, 36 million deaths are due to non communicable diseases (NCDs) like cancer, stroke, diabetes and cardio-vascular diseases, and it is increasing! Assumed to be old-age diseases, the NCDs are now taking toll at younger ages (below 60 y) also. Cancer kills 7.6 million people a year; tobacco use kills about 6 million and alcohol 2.5 million a year.
Bhopal gas-leak tragedy, in the year 1984, killed over 3000 people, within days. In Chernobyl nuclear reactor accident, only 47 people died of acute radiation dose and fire burns. Some more may die of cancer over the years. Similarly, over 9000 people died of Tsunami in Japan and the on-going nuclear situation in Fukushima may also cause some fatalities over the years. These deaths are not due to acute radiation doses.
Over 1.5 lakh deaths a year are reported due to accidents on Indian roads. Today, while driving from Belapur, Navi Mumbai to Chembur (18 km), I met near-death situation on the road at least 5 times. This is not due to my fault but due to other’s faults such as: cutting lanes, drunken driving and three wheeler nuisance. Road discipline simply does not exist in Mumbai roads.
Under such scenarios, some vested interests and politicians are creating nuisance everywhere criticizing against developmental projects, particularly nuclear power plants at Jaitapur. Reason is safety! If they are so much concerned about safety, what they are doing about safety on the roads, high pollution levels, floods, crime, etc?
If one sees the risks in proper perspective, it is unimaginable to understand why the designers are spending so much money on safety in nuclear power plants? How many thousands are spend to save ONE life in nuclear power sector?
Let us spend our resources in proportionate to the risks. Say no for over-protection.
Friday, April 29, 2011
Monday, April 25, 2011
ICRP New publication - ICRP-113, 2009, Education and Training in Radiological Protection
Title: Education and Training in Radiological Protection for Diagnostic and Interventional Procedures, ICRP Publication 113, ICRP, Ann. ICRP 39 (5), 2009 - New Publication from ICRP
Abstract: In view of the increase in the number of diagnostic and interventional medical procedures using ionizing radiations, there is compelling need for education and training of medical staff (including medical students) and other healthcare professionals in the principles of radiation protection.
Based on the current ICRP basic recommendations (2007) for such education and training of these individuals, the ICRP is providing guidance through ICRP-113 regarding the necessary radiological protection education and training for use by various categories of medical practitioners and other healthcare professionals who perform or provide support for diagnostic and interventional procedures utilizing ionizing radiation and nuclear medicine therapy.
The publication is useful for regulators, health authorities, medical institutions, and professional bodies with responsibility for radiological protection in medicine; an the industry that produces and markets the equipment used in these procedures and universities and other academic institutions responsible for the education of professionals involved in the use of ionizing radiation in health care.
Advice is also provided on the accreditation and certification of the recommended education and training. The accredited organization is required to meet standards that have been set by the authorized body (based on ICRP News).
Abstract: In view of the increase in the number of diagnostic and interventional medical procedures using ionizing radiations, there is compelling need for education and training of medical staff (including medical students) and other healthcare professionals in the principles of radiation protection.
Based on the current ICRP basic recommendations (2007) for such education and training of these individuals, the ICRP is providing guidance through ICRP-113 regarding the necessary radiological protection education and training for use by various categories of medical practitioners and other healthcare professionals who perform or provide support for diagnostic and interventional procedures utilizing ionizing radiation and nuclear medicine therapy.
The publication is useful for regulators, health authorities, medical institutions, and professional bodies with responsibility for radiological protection in medicine; an the industry that produces and markets the equipment used in these procedures and universities and other academic institutions responsible for the education of professionals involved in the use of ionizing radiation in health care.
Advice is also provided on the accreditation and certification of the recommended education and training. The accredited organization is required to meet standards that have been set by the authorized body (based on ICRP News).
Tuesday, April 5, 2011
Important of Exclusion Zone in safety of public
Exclusion Zone is one of the five and the last barriers before radioactive releases from nuclear power plants reach the public domain. This is not a physical barrier. However, no permanent residence is allowed within the 1.6 km radius from nuclear reactor. This ensures significant dilution of an airborne radioactive release before it reaches any public habitation, thus reducing the resulting public dose. Radiation dose to the public at the distance of 1.6km is calculated for the releases during normal/abnormal working of the nuclear reactors, to check compliance with the regulatory limits for releases to the public domain.
Thus Exclusion Zone is an important barrier which has prevented large public doses during the on-going nuclear emergency situation at Fukushima nuclear power reactor in Japan.
In spite of the best possible design and safety records, accidents can still occur and hence the concept of defense-in-depth should never be compromised.
Thus Exclusion Zone is an important barrier which has prevented large public doses during the on-going nuclear emergency situation at Fukushima nuclear power reactor in Japan.
In spite of the best possible design and safety records, accidents can still occur and hence the concept of defense-in-depth should never be compromised.
Thursday, March 31, 2011
Uranium in drinking water and chemical toxicity
As per US-EPA (US-DOE, 2007) the maximum concentration level (MCL) in drinking water is 0.03mg/L or 27pCi/L for natural uranium. Level of 67pCi/L of natural uranium in drinking water is also suggested by some authors. It is assumed that 02 to 5% of the intake is absorbed in to the blood stream of which 22% is deposited on bone, 12% in kidneys and rest excreted. The uranium deposited in kidneys is excreted within few days. The mean U concentration in drinking water detected in some SU cities is 2.55 micro-g/L
WHO threshold value to prevent sub-clinical renal effects is 0.002mg/L.
The chemical toxicity value for soluble salts of uranium is 0.003mg /kg-day. This is the highest dose that can be taken every day, over a life time without causing adverse health effects. This is generated based on animal studies and normalized to humans using an uncertainty factor of 1000. Lowest observed adverse health effect is at an intake level of soluble uranium of 3mg/kg-day. Daily intake of uranium by adults (60kg) through air, water and food is 2.2 micro-g and total body burden of uranium in humans is 40 micro-g. At equilibrium, the excretion rate through urine is 4.4 micro-g per day.
In alkaline conditions in the kidney, uranium hydrogen carbonate complex is most stable and hence uranium is excreted out from the kidney. In acidic conditions the uranium (as uranyl ion) gets deposited in the tubular wall in the kidney. The most common renal injury caused by uranium in experimental animals is damage to the proximal convoluted tubules in kidney. Nephritis is the primary induced effect of uranium in humans.
The threshold uranium concentration for chemical toxicity is 1 micro-g/g of kidney tissue. For protection of the public, further safety factor of 10 is applied and values in the range of 0.1 to 0.3 micro-g/g of the tissue are reported as threshold limits for public by some authors.
WHO threshold value to prevent sub-clinical renal effects is 0.002mg/L.
The chemical toxicity value for soluble salts of uranium is 0.003mg /kg-day. This is the highest dose that can be taken every day, over a life time without causing adverse health effects. This is generated based on animal studies and normalized to humans using an uncertainty factor of 1000. Lowest observed adverse health effect is at an intake level of soluble uranium of 3mg/kg-day. Daily intake of uranium by adults (60kg) through air, water and food is 2.2 micro-g and total body burden of uranium in humans is 40 micro-g. At equilibrium, the excretion rate through urine is 4.4 micro-g per day.
In alkaline conditions in the kidney, uranium hydrogen carbonate complex is most stable and hence uranium is excreted out from the kidney. In acidic conditions the uranium (as uranyl ion) gets deposited in the tubular wall in the kidney. The most common renal injury caused by uranium in experimental animals is damage to the proximal convoluted tubules in kidney. Nephritis is the primary induced effect of uranium in humans.
The threshold uranium concentration for chemical toxicity is 1 micro-g/g of kidney tissue. For protection of the public, further safety factor of 10 is applied and values in the range of 0.1 to 0.3 micro-g/g of the tissue are reported as threshold limits for public by some authors.
Monday, March 28, 2011
Physical Barriers to Environmental Release of radioactive releases in case of reactor accidents: Defense-in-Depth concept
The following five barriers are built into the reactor design to prevent radioactivity escaping from the reactor to the public:
1. Ceramic Fuel - The ceramic uranium dioxide fuel in pellet form entraps most of the fission products generated due to the fission reaction in the fuel. These fission products would be released if the fuel were to melt. The fuel has a high melting point, but continuous cooling is required so that the fuel is not over-heated resulting in melting of the fuel. Another safety feature of the ceramic fuel is that it is relatively chemically inert with the heavy water coolant.
2. Fuel Sheath (cladding) - The fuel pellets are enclosed in a high integrity, welded zircalloy sheath. This sheath contains the gaseous and volatile fission products which escape from the pellets. The sheath is designed to withstand the stresses resulting from pellet thermal expansion, gaseous fission product build-up and external hydraulic pressure.
3. Heat Transport System Boundary - The high integrity pressure tubes, piping, and vessels contain most fission products escaping via sheath defects until they are removed via the coolant purification system.
4. Containment Boundary - This is designed to withstand the pressure surge of a worst case LOCA, with a small ‘puff release’ during the overpressure transient. Post LOCA containment venting via a filtered, monitored pathway minimizes the environmental radioactive release.
5. Exclusion Zone - No permanent residence is allowed within a 1.6 km radius from nuclear reactor. This ensures significant dilution of an airborne radioactive release before it reaches any public habitation, thus reducing the resulting public dose.
Inadequate fuel cooling due to cooling system failure, the situation which is prevailing now at Fukushima nuclear power reactor in Japanese, results in overheating of the fuel, with potential for large scale fuel failures. In the event of large scale fuel failures, at least two of the five physical barriers would be breached, i.e., the fuel and the fuel sheath. In the case of a LOCA, the third barrier, the heat transport system is also breached, leaving only the containment and exclusion zone barriers.
In the case of a LOCA coincident with containment failure (dual failure), only the exclusion zone would remain as a physical barrier. Thus, the Containment boundary is a very strategic defense-in-depth barrier to fission product release in to the public domain. .
1. Ceramic Fuel - The ceramic uranium dioxide fuel in pellet form entraps most of the fission products generated due to the fission reaction in the fuel. These fission products would be released if the fuel were to melt. The fuel has a high melting point, but continuous cooling is required so that the fuel is not over-heated resulting in melting of the fuel. Another safety feature of the ceramic fuel is that it is relatively chemically inert with the heavy water coolant.
2. Fuel Sheath (cladding) - The fuel pellets are enclosed in a high integrity, welded zircalloy sheath. This sheath contains the gaseous and volatile fission products which escape from the pellets. The sheath is designed to withstand the stresses resulting from pellet thermal expansion, gaseous fission product build-up and external hydraulic pressure.
3. Heat Transport System Boundary - The high integrity pressure tubes, piping, and vessels contain most fission products escaping via sheath defects until they are removed via the coolant purification system.
4. Containment Boundary - This is designed to withstand the pressure surge of a worst case LOCA, with a small ‘puff release’ during the overpressure transient. Post LOCA containment venting via a filtered, monitored pathway minimizes the environmental radioactive release.
5. Exclusion Zone - No permanent residence is allowed within a 1.6 km radius from nuclear reactor. This ensures significant dilution of an airborne radioactive release before it reaches any public habitation, thus reducing the resulting public dose.
Inadequate fuel cooling due to cooling system failure, the situation which is prevailing now at Fukushima nuclear power reactor in Japanese, results in overheating of the fuel, with potential for large scale fuel failures. In the event of large scale fuel failures, at least two of the five physical barriers would be breached, i.e., the fuel and the fuel sheath. In the case of a LOCA, the third barrier, the heat transport system is also breached, leaving only the containment and exclusion zone barriers.
In the case of a LOCA coincident with containment failure (dual failure), only the exclusion zone would remain as a physical barrier. Thus, the Containment boundary is a very strategic defense-in-depth barrier to fission product release in to the public domain. .
Thursday, March 24, 2011
Contamination of foods and feedstuffs by the nuclear disaster
The releases from the damaged reactors are contaminating food and feedstuffs in the nearby areas in Japan. Radioactive iodine will be seen quickly in the milk. As most of the radioactive particles may end up in the ocean it is imperious to avoid sea foods of any kind. Water sources are likely to be contaminated. The Japan government declared that the tap water in Tokyo is contaminated with radioactive iodine and is unsafe for infants.
Continuous monitoring for radioactivity of the food products, milk and drinking water is being done to ensure that the radiation exposure of the public does not exceed the acceptable limits prescribed by the WHO. Since some of the radioactive isotopes released are having half lives in years, the food chain safety will be compromised in the next decades by the situation in Fukushima.
The WHO guideline levels in drinking water, for the most predominant radio-nuclides, Iodine-131 and Cesium-137, in the releases from the reactors are: 0.01 Bq/mL. These guideline levels of radionuclides in drinking water were calculated on the basis of an annual dose criterion of 0.1 mSv (10mR) from drinking 2 liters of water per day. The average natural background radiation to which we are all exposed is 2 mSv in a year.
The International Atomic Energy Agency (IAEA) has also been monitoring the environment for radioactivity and radiation levels at the nearby areas from the Fukushima plant in Japan. As per IAEA update, the dose-rate results ranged from 0.8 to 9.1 micro-Sievert per hour. The beta-gamma activity contamination measurements ranged from 0.08 to 0.9 MBq per square metre.
The Agency continues to receive data confirming high levels of radioactivity (above permissible limits) in food, notably spinach, in samples taken from 37 locations in the vicinity of five cities south of the Fukishima site. Higher levels of both Iodine-131 and Caesium-137 have been measured by the Japanese authorities in milk, water, in spinach and some other fresh vegetables. In view of this, it is reported that distribution of food from the areas affected has been restricted. The Japanese authorities are monitoring the situation in the rest of the country.
Further radioactivity releases from the stricken reactors in to the environment should be controlled somehow to keep the public exposures as low as possible.
Continuous monitoring for radioactivity of the food products, milk and drinking water is being done to ensure that the radiation exposure of the public does not exceed the acceptable limits prescribed by the WHO. Since some of the radioactive isotopes released are having half lives in years, the food chain safety will be compromised in the next decades by the situation in Fukushima.
The WHO guideline levels in drinking water, for the most predominant radio-nuclides, Iodine-131 and Cesium-137, in the releases from the reactors are: 0.01 Bq/mL. These guideline levels of radionuclides in drinking water were calculated on the basis of an annual dose criterion of 0.1 mSv (10mR) from drinking 2 liters of water per day. The average natural background radiation to which we are all exposed is 2 mSv in a year.
The International Atomic Energy Agency (IAEA) has also been monitoring the environment for radioactivity and radiation levels at the nearby areas from the Fukushima plant in Japan. As per IAEA update, the dose-rate results ranged from 0.8 to 9.1 micro-Sievert per hour. The beta-gamma activity contamination measurements ranged from 0.08 to 0.9 MBq per square metre.
The Agency continues to receive data confirming high levels of radioactivity (above permissible limits) in food, notably spinach, in samples taken from 37 locations in the vicinity of five cities south of the Fukishima site. Higher levels of both Iodine-131 and Caesium-137 have been measured by the Japanese authorities in milk, water, in spinach and some other fresh vegetables. In view of this, it is reported that distribution of food from the areas affected has been restricted. The Japanese authorities are monitoring the situation in the rest of the country.
Further radioactivity releases from the stricken reactors in to the environment should be controlled somehow to keep the public exposures as low as possible.
Tuesday, March 22, 2011
Radiation dose control from releases from “damaged” nuclear reactors
The recent nuclear crisis in Japan where four nuclear power reactors were damaged due to earthquake has raised questions with respect to the public exposures. In such accidental situations, the atmospheric releases from the damaged reactor core are mainly radio-nuclides in vapour form, such as of Iodine. Let us take an example of radioactive Iodine isotope, I-131.
The half-life - the time required for the radioactivity to reduce by one-half - for I-131 isotope is 8 days. Since the half life is considerably long, the isotope can travel long distances along the direction of the wind. On the way, the iodine isotope gets deposited on the soil, on water surfaces and on grass and “contaminates” them. Human consumption of such contaminated items results in radiation dose to the exposed population. Biologically, the thyroid hormone contains iodine in stable (not radioactive) form. If one is exposed to radioactive iodine, it will get uploaded into the thyroid and gets deposited there, giving radiation dose. Prophylaxis is a process where the thyroid is deliberately saturated by “stable” iodine and hence the uptake of “radioactive” iodine from the releases is minimized. A tablet of Potassium iodide/iodate (around 130 mg) is consumed, just before or just after the releases, for “blocking” the thyroid from radioactive iodine uptake.
In general, staying indoors, use of proper respirators and consumption of stable iodine tablets (if advised), reduces exposure of people from the atmospheric releases of radioactive isotopes/materials.
Public needs to be sensitized on this aspect for their protection.
The half-life - the time required for the radioactivity to reduce by one-half - for I-131 isotope is 8 days. Since the half life is considerably long, the isotope can travel long distances along the direction of the wind. On the way, the iodine isotope gets deposited on the soil, on water surfaces and on grass and “contaminates” them. Human consumption of such contaminated items results in radiation dose to the exposed population. Biologically, the thyroid hormone contains iodine in stable (not radioactive) form. If one is exposed to radioactive iodine, it will get uploaded into the thyroid and gets deposited there, giving radiation dose. Prophylaxis is a process where the thyroid is deliberately saturated by “stable” iodine and hence the uptake of “radioactive” iodine from the releases is minimized. A tablet of Potassium iodide/iodate (around 130 mg) is consumed, just before or just after the releases, for “blocking” the thyroid from radioactive iodine uptake.
In general, staying indoors, use of proper respirators and consumption of stable iodine tablets (if advised), reduces exposure of people from the atmospheric releases of radioactive isotopes/materials.
Public needs to be sensitized on this aspect for their protection.
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