The oil & gas activity provides about 90% of Nigeria’s foreign earnings and more than 80% of the nation’s national income. However, the extraction processes which take oil and gas from the ground leave behind dangerous wastes. Some of these hazardous wastes generated in conjunction with oil & gas activity have been discussed in the authors’ article published on 21 January, 2009 in this website. This edition deals specifically with radioactive sources and wastes arising from the oil & gas exploration and production activity.
Naturally occurring radioactive materials (radionuclides) present under the ground may, during oil & gas drilling, be enhanced to elevated and harmful levels in produced waters, drilling mud, or oil and gas extraction equipment. The radionuclides may be present in mineral scale, sludge, slimes or evaporation ponds or pits for produced waters.
There are also man-made radioactive sources used in improving recovery from oil and gas wells and in detecting leaks in oil and gas pipes. These radioactive sources and the radioactive wastes (arising from man-made and naturally-occurring radionuclides) produce ionizing radiations which are harmful to oil & gas workers and members of the general public if not properly handled.
The oil & gas industry is the major user of radioactive sources in Nigeria. By the same token, it is also the largest producer of radioactive wastes. The national drive to improve oil & gas recovery from reservoirs and increase crude oil reserve to 40 billion barrels by the year 2010 would require nuclear well-logging and increased use of radioactive sources. Hence, this calls for radiation safety regulator to take more stringent measures to enforce radiation protection safety and security of radioactive sources in the oil & gas industry
Radioactive Sources in Oil and Gas Industry
There are two classes of radioactive sources that oil and gas workers and the public should be concerned about:
1) Technologically – Enhanced Naturally-occurring radioactive materials (TENORM or NORM):
There are over 100 naturally-occurring radionuclides, but public health concerns are limited to radionuclides in the uranium and thorium decay series. This is due to their relative abundance and toxicity. Others like naturally occurring potassium-40 have not been known to accumulate from oil and gas production. Radium-226 and radium 228 are the two most common to travel up with oil and gas at elevated levels. They come from the uranium -238 and thorium-232 decay chains, respectively. Other radioactive elements associated with the decay series are radon gas and lead-210. There is long-term radiological concern for radium-226, because of its long half-life (1,600 years). Lead-210 has a 22-year half life.
During drilling, the radon gas may be released to the atmosphere and inhaled by unprotected workers. The elevated levels of NORM (radium-226 & radium-228 ) are actually found in the produced waters, drilling mud and scaled sludge. The NORM residues also contaminate oil & gas equipment and facilities such as pipes, tanks, separators, etc. NORM is the most toxic waste oil and gas wells can generate.
2) Artificial Radioactive Sources:
Radioactive sources are required for industrial radiography and nuclear well-logging. Industrial radiography is a technique used to test the integrity of welds and to detect leaks caused by cracks and corrosion in pipes. The nuclear well-logging, which improves recovery from oil and gas wells, also uses radioactive materials. These radioactive sources become radioactive wastes when they are no longer useful, and they must be properly disposed of. These include Cs-137 and many radioactive tracers.
Effects of radioactive sources on biological systems.
The radioactive sources and wastes emit ionizing radiations which have harmful effects on mankind and other biological systems. A person can get a dose of the ionizing radiation by inhalation, ingestion, or physical contact with radioactive sources and wastes. It can also be through food chain (i.e. by consumption of contaminated fish, shellfish or other animals).
Ionizing radiation affects living cells, either damaging them or by creating substances (radicals) which disrupt the normal cell division. As a result, cells die or mutate, affecting the health of affected person (somatic effects) and possibly affecting future generations of the affected person (hereditary effects). Excessive exposure to radiation has serious health implications such as susceptibility to genetic diseases, leukemia, cancers, etc.
The half-life of a radioactive substance determines the number of years the harmful effects of the radionuclide will persist in the biological systems. The effective half-life, Teff of a radioactive isotope in the body is the time taken for the activity of the isotope in the body to reduce to half its initial activity. For instance, oil & gas related produced waters, mud and scaled sludge containing elevated levels of radon-226(with half-life of 1600years) will have serious radiological safety concerns for centuries at the sites they are indiscriminately disposed of.
NORM, if not properly handled, can hurt people and the environment as any radioactive waste can. Radon gas from oil and gas wells is the second-leading cause of lung cancer. Radium-226 and radium -228, the two most common elements in NORM, emit alpha particles and gamma radiation as they decay. They may not be harmful to oil and gas on- site workers who follow workers safety procedure. But they pose serious health risks to the public if the wastes are indiscriminately disposed of in the environment.
Regulator and Regulations on Oil and Gas Related Radioactive Wastes
The Nuclear Safety and Radiation Protection Act of 1995 was the first major legislation on radiation safety to be promulgated in Nigeria. The Act led to the establishment of the Nigerian Nuclear Regulatory Authority (NNRA). The Federal government also established the National Institute for Radiation Protection and Research, located at the University of Ibadan as the technical/scientific support arm of the NNRA.
The Nuclear Safety and Radiation Protection Act of 1995 charges the regulator with the responsibility for nuclear safety and radiological protection regulation in Nigeria. The Act requires the regulator to ensure protection of life, health, property and the environment from the harmful effects of ionizing radiation, while allowing beneficial practices involving exposure to ionizing radiation. The Act also has provisions for sanctions ranging from fines, closure of facilities to imprisonment.
Based on experiences of the regulator (NNRA) on radiological incidents and accidents in the petroleum industry, it has fashioned out two other enforceable regulations on radiation safety issues concerning oil & gas activity. The regulations, which have been gazetted with the approval of the President, Commander-in-Chief of the Armed Forces, were launched in July, 2008 in Port Harcourt. The Regulations are:
a) Nigerian Radiation Safety in the Management of Naturally- occurring Radioactive Materials (NORM) Regulations, 2008.
b) Nigerian Radiation Safety in Nuclear Well-Logging Regulations, 2008.
There are genuine public concerns over indiscriminate and dangerous disposal of radioactive wastes by the oil and gas industry, as these wastes pose serious health risks. A major oil exploration and production multinational company operating in Nigeria was caught by the law enforcement agency while trafficking in wastes suspected to be radioactive substances. The oil com
pany and its corporate /individual accomplices were said to have conspired between September 9 and October 9, 2006 to carry, transport, handle, store and transfer radioactive wastes to an unauthorized person. The dangerous wastes were transported from Port Harcourt, Rivers state to Warri, Delta State without valid license or authorization from the Nigerian Nuclear Regulatory Authority.
Consequently, the Federal Government filed a criminal case against the accused before a Federal High Court in Abuja on March 23, 2007. In the charge cited as FHC/ABJ/CR/30/2007, the Federal government stated that the accused committed offences punishable under section 45 (1) (a) of the Nuclear Safety and Radiation Protection Act 1995. The story was run on March 26, 2007 by many Nigerian National Dailies, including This Day Newspaper.
There are many undiscovered and unreported cases of illegal dumping of oil and gas related radioactive wastes (i.e spent radioactive sources, produced waters/muds/scaled sludge laden with elevated levels of NORM) in the Nigerian environment, posing threats to life, public health and ecological systems. It is hoped that the recently launched regulations on Nuclear well-logging and NORM will further empower the regulator to enforce safe temporary storage of radioactive wastes arising from oil and gas activity prior to permanent disposal in environmentally sound manner.