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Misgivings over Safety Control in Nuclear Power Plants
The severity level of the Daiichi nuclear power plant disaster in Fukushima, Japan, last March, 2011, has been raised from a scale of level five to level seven. Accordingly, the severity rose as officials of Tokyo Electric Power Co. (TEPCO) disclosed that the damages to the plant have progressed --- fuel rods have melted in three of the plant’s fuel reactors.
Fears over the effects of nuclear radiation continue to mount as critical information about the power plant’s faulty safety controls came into the open. Controversial issues related to the plant’s safety included TEPCO’s 2002 admission that the company had been submitting fake maintenance reports to the government’s regulators. In 2007, the electric company also suppressed information about six incidents of emergency stoppages in the Daiichi nuclear plant.
Mitsuhiko Tanaka, a former Hitachi-Daiichi nuclear engineer revealed that the steel pressure vessel, which contains the fuel rods in Daiichi’s number four reactor, was flawed from the start.
Tanaka admitted that in 1975, his team discovered that braces, which should have been placed inside the vessel, were missing. Moreover, he and his team also found that the vessel’s steel walls warped when subjected to temperature levels of 600o Celsius as part of their strengthening processes.
Tanaka further admitted that he had orchestrated a cover-up by submitting fake reports in order to pass safety inspections. Doing so had saved Hitachi, the vessel manufacturer from bankruptcy; inasmuch as the Japanese government’s law for flawed vessels demanded that they should be scrapped altogether.
Ten years later and two months after the Chernobyl nuclear accident, engineer Tanaka decided to report the cover-up to Japan’s Ministry of Economy, Trade and Industry. Unfortunately, Tanaka's revelations did not receive much attention to merit a full-scale investigation and inspection of the Daiichi power plant.
Four more nuclear facilities in Japan, namely, Chubu Electric Power Co., Tohoku Electric Power Co. and Hokuriku Electric Power Co. and Kansai Electric Power Co. (Osaka) have followed suit in admitting that they had also submitted fake safety reports. Other disclosures included information that Chubu Electric Power Co. is located near Japan's earthquake fault-lines. On top of all these, there were numerous suppressed reports of nuclear accidents in different facilities during the past years, all of which emanated from omissions in safety systems.
In view of all these revelations, the greater concerns to consider are the effects of nuclear radiation brought about by accidents once they happen. A level seven nuclear accident denotes that the nuclear power plant has sustained severe damages and there is a total breakdown in the plant’s safety control mechanisms.
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Understanding the INES Scale
The “International Nuclear and Radiological Events (INES) Scale" indicates the severity by which radioactive materials impact the surroundings after a nuclear event. It ranges from a scale of one to seven, for which levels one (1) to three (3) are classified as an “incident" while levels four (4) to seven (7) fall under the “accident" classification. Understand that any increase in level, raises the severity of the problems by tenfold.
Level One – The event is related to an anomaly or theft or breach of operational limits in a nuclear facility and does not require radiological barriers and control since it does not pose grave danger to the people and the environment.
Level Two – The incident involves a breakdown in the safety function of the power plant’s emergency power supply. There is a resulting failure in accessing the control system at the plant’s accelerator facility, in which radiation levels were detected at more than 50 mSV/h in the operating area.
Level Three – This is considered as serious nuclear incident, which involves the occurrence of a fire that causes near accident, resulting in loss of the safety systems at the facility. The problem is aggravated by the release of a substantial amount of radioactive concentration, but remains contained within the nuclear installation.
Level Four – This elevates the incident to the accident classification as the power plant has lost its defense-in-depth systems, thereby, releasing substantial amounts of radioactive material within the nuclear installation as a result of fuel melts. Amounts released are more than 0.1 percent of the nuclear plant’s core inventory, which can be expected to reach and affect the public.
Level Five – This type of accident is determined to have a wider coverage of the consequences inasmuch as the damages sustained is in the plant facility’s reactor core and there is loss of the defense-in-depth system. There are large quantities of radioactive material released within the installation and the likeliest possibility of exposing the public to harmful contamination. The criticality of the accident is expected to include the occurrence of fire.
Level Six – Considered as a serious power plant accident where there is loss of the defense-in-depth system and that radiological measures and control barriers are rendered ineffective. This type of accident calls for the implementation of the planned countermeasures against the significant release of radioactive materials that affect the public and the environment.
Level Seven – This denotes a major nuclear accident. The release of radioactive material is widespread and the problems more complex. Measures taken extend beyond the planned consequence and risk management strategies.
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Significance of mSv as a Unit of Radiation Exposure Measurement
Comprehend that the metric unit “mSv" denotes the measure of radioactive energy that penetrates human or living tissues.
The letters “Sv" stand for Sievert (See-vert), which measures the amount of energy absorbed by the body that is expected to create harmful biological effects on the human being.
The “m" stands for Milli or a thousandth part of the energy absorbed. In some cases the measure is expressed as microsievert, which means a millionth part of the radioactive absorption.
If the measure is expressed as “mSv/h", the “h" stands for hour. In which case, the measurement context denotes the rate by which a specific amount of radioactive energy penetrates the human tissues in a matter of one hour.
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Potential Radiation-Related Problems
Responders to the accident, the rescuers and the plant workers have the highest potential and degree of exposure due to their involvement in the emergency activities.
In the event that a level seven nuclear power plant accident takes place, the people, land and everything within 20 to 30 kilometer radius around the plant’s vicinity are contaminated by a mixture of radioactive substances. The latter enters the body by way of skin penetration, inhalation of contaminated air and/or through the ingestion of contaminated food or water.
These substances are called “radionuclides" which were produced during the fission that transpired inside the reactor core. The most harmful radionuclides that can affect human health are the (1) radioactive iodine and (2) radioactive caesium.
Humans are said to be exposed to low doses of these radiologically active substances as part of their day to day activities. They become threats to life and the surroundings once they exceed the established safety levels per person.
The first signs that the amount of radioactive materials received by human tissues has been excessive are: skin reddening, radiation burns, hair loss, and a disorder known as Acute Radiation Syndrome (ARS).
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What is Acute Radiation Syndrome?
A person, who was exposed to high doses of radiation over a short period of time, is liable to develop ARS because the radioactive material that entered his body has reached and affected his internal organs.
Typically, a person afflicted with ARS experiences nausea, vomiting and diarrhea within minutes or days after being exposed to the radionuclides. The symptoms are expected to last for several minutes or days and are likely to come and go. This will later develop into a more serious health condition wherein the afflicted person debilitates due to loss of appetite, fever, fatigue and in most severe cases, seizures or becomes comatose.
ARS becomes fatal if the illness is allowed to progress into a state of bone marrow deterioration, because such a condition eventually leads to infection and internal bleeding; hence, it is important to seek immediate medical attention in order to increase one’s chances of recovering from the disorder.
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Radioactive Iodine and Thyroid Cancer
The human body readily absorbs iodine whether by way of inhalation or ingestion. Once the substance enters the body, it is capable of crossing the bloodstream. As radioactive iodine flows into the body, the thyroid’s absorption process will include the said substance as part of the nutrients. Excessive radioactive accumulation can cause cell mutation or cell destruction by affecting nearby cells, which increases the risk of developing into thyroid cancer.
- The World Health Organization (WHO) furnishes information that taking potassium iodide pills can help lower the risks of thyroid cancer, since the medication can prevent the thyroid from reabsorbing the radioactive iodine carried by the blood cells.
- The risks of thyroid cancer are higher among children who were exposed to radioactive doses of more than 100 mSv.
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Radioactive Caesium and Its Effects
Radioactive caesium that is contacted, inhaled or ingested, can easily penetrate the soft-muscle tissues and could cause involuntary muscular reflexes, spasms and damage to the reproductive organ.
- The concern over caesium as a radionuclide is long-term effects and greater potential of developing into a cancerous health disorder. Unlike radioactive iodine, caesium takes longer to disintegrate once the substance enters the body and cannot be prevented from participating in the re-absorption processes while inside the human body.
- Caesium-137 has a half-life of 30 years, which denotes that it will take around 240 years before the substance is converted or ceases to be a radioactive substance.
- Caesium-134 has a half-life of two years, which will take about 20 years before it fully loses its radioactive properties.
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How Radiation Can Affect Fetuses and Children
The unborn child of a pregnant woman, exposed to radioactive materials, is at risk of brain damage. Doses of radiation exceeding 100mSv can cause fetal brain damage during the 8th to 15th week of the gestation period, and 200 mSv during the 16th-25th week. Fetal exposure, regardless of gestation period increases the risks of childhood cancer.
Children are said to be the most affected due to their inability to fully understand damage brought about by life changing events. Loss of property, lives, relocation, health and even a community, cause emotional stress to everyone directly affected, particularly the younger generations.
Nevertheless both adults and children may show signs of emotional distress, which are exhibited by the following symptoms:
- Anxiety over the effects of radiation and possible development of cancer as an illness
- Loss of appetite
- Trouble sleeping
- Behavioral changes common among children, i.e. clinging, nail-biting, bed wetting, irritability
- Difficulty in overcoming fear and developing new ones
- Feelings of guilt and suicidal tendencies
- Disorganized behavior
These symptoms are typically manifested for days, weeks or months and the WHO gives advice that anyone with such symptoms should see a health professional. The primary objective is to help the affected person overcome his grief, loss or anxieties. Early management is said to be the best way to prevent any emotional distress from developing into a long-term mental illness. Psychological stress is said to be the most detrimental and lingering health disorder that affects those who survived a nuclear accident.
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Effects of Radionuclides on the Environment
Although food contamination is one of the many effects of radiological exposure, food substances that were dispatched prior to the disastrous event are not affected. Radioactive iodine in food has a short-term effect on the environment due to its shorter half-life as it loses its radiologic properties within a shorter life span.
1. This stands opposed to radioactive caesium C-137 and C-134, which lingers in the environment in a radioactive state for longer durations of up to 240 years and 20 years, respectively.
2. Rain water, snow and atmospheric deposits bring down the radioactive materials onto the Earth’s surface and are absorbed by the soil or combines with water. Agricultural produce grown from contaminated soil and/or irrigated with contaminated water are likely to contain radionuclides. Plants naturally absorb the harmful substances as part of the soil’s nutrients.
3. Animal feeds, fodder, pastures, and open-sources of drinking water that were contaminated during a level seven nuclear disaster, are later ingested by animals that are oblivious to the hazards. These animals are likely to produce milk or eggs or become sources of food, thereby transferring the undestroyed radionuclides to another animal or to humans.
4. Bodies of water are also contaminated by the radioactive nuclides and likewise affect aquatic animals particularly those consumed as food by humans. The contamination of algae and planktons, on which aquatic animals rely for subsistence, can likewise cause the indirect transfer of radioactive materials to humans.
The effects of nuclear radiation to public health and the environment are many, which were all monitored and documented by organizations like the WHO and the IAEA (International Atomic Energy Agency). However, it seems that those who operate the nuclear power plants have learned very little from all the accidents that have happened.
The causes of most nuclear power plant disasters can be easily summarized as system flaws and failures that were deliberately ignored and intentionally suppressed.
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Reference Materials and Image Credit Section
- By Clenfield, Jason "Japan Nuclear Disaster Caps Decades of Faked Reports, Accidents" - Bloomberg Mar 18, 2011 4:52 PM
- IAEA.org "The International Nuclear and Radiological Event Scale"
- WHO- Health Action in Crises May 12,2011
- CDC.govt - "Acute Radiation Syndrome (ARS): A Fact Sheet for the Public"
- Fukushima7 by Rama C. Hoetzlein /Wikimedia
- International Nuclear Event Scale Triangle en by 102orion/Wikimedia
- Cae halle Germany 2010 by Herder3 /Wikimedia
- Hiroshima girl by Dake at fr.wikipedia/ Wikimedia /Wikimedia
- Illu thyroid parathyroid, a work of the United States Federal Government / Wikimedia
- Cs-137 from nuclear tests by Harold L. Beck, National Cancer Institute/Wikimedia
- Japan Evacuees Brave Radiation Fears to Briefly Return Home by Steve Herman - VOA April 12 2011 Namie-05- Wikimedia
Cattle have been left to forage on their own for the past month, Namie, Fukushima Pref., Japan, April 12 2011 / Wikimedia VOA by Steve Herman