The worldwide NORM production and a fully automated gamma-ray spectrometer for their characterization

Materials containing radionuclides of natural origin and being subject to regulation because of their radioactivity are known as Naturally Occurring Radioactive Material (NORM). By following International Atomic Energy Agency, we include in NORM those materials with an activity concentration, which is modified by human made processes. We present a brief review of the main categories of non-nuclear industries together with the levels of activity concentration in feed raw materials, products and waste, including mechanisms of radioisotope enrichments. The global management of NORM shows a high level of complexity, mainly due to different degrees of radioactivity enhancement and the huge amount of worldwide waste production. The future tendency of guidelines concerning environmental protection will require both a systematic monitoring based on the ever-increasing sampling and high performance of gamma-ray spectroscopy. On the ground of these requirements a new low-background fully automated high-resolution gamma-ray spectrometer MCA_Rad has been developed. The design of lead and cooper shielding allowed to reach a background reduction of two order of magnitude with respect to laboratory radioactivity. A severe lowering of manpower cost is obtained through a fully automation system, which enables up to 24 samples to be measured without any human attendance. Two coupled HPGe detectors increase the detection efficiency, performing accurate measurements on small sample volume (180 cm³) with a reduction of sample transport cost of material. Details of the instrument calibration method are presented. MCA_Rad system can measure in less than one hour a typical NORM sample enriched in U and Th with some hundreds of Bq kg^?1, with an overall uncertainty less than 5 %. Quality control of this method has been tested. Measurements of three certified reference materials RGK-1, RGU-2 and RGTh-1 containing concentrations of potassium, uranium and thorium comparable to NORM have been performed. As a result, this test achieved an overall relative discrepancy of 5 % among central values within the reported uncertainty.     

Low gamma counting for measuring NORM/TENORM with a radon reducing system

A detection system for counting low levels of gamma radiation was built by upgrading an existing rectangular chamber made of 18 metric tonne of steel fabricated before World War II. The internal walls, the ceiling, and the floor of the chamber are covered with copper sheets. The new detection system consists of a stainless steel hollow cylinder with variable circular apertures in the cylindrical wall and in the base, to allow introduction of a NaI (Tl) crystal, or alternatively, a HPGe detector in its interior. This counting system is mounted inside the larger chamber, which in turn is located in a subsurface air-conditioned room. The access to the subsurface room is made from a larger entrance room through a tunnel plus a glass anteroom to decrease the air-exchange rate. Both sample and detector are housed inside the stainless steel cylinder. This cylinder is filled with hyper pure nitrogen gas, before counting a sample, to prevent radon coming into contact with the detector surface. As a consequence, the contribution of the ²¹⁴Bi photopeaks to the background gamma spectra is minimized. The reduction of the gamma radiation background near the detector facilitates measurement of naturally occurring radioactive materials (NORM), and/or technologically enhanced NORM (TENORM), which are usually at concentration levels only slightly higher than those typically found in the natural radioactive background.     

NORM activity concentration in sediment cores from the Peninsular Malaysia East Coast Exclusive Economic Zone

Study for distribution of Naturally Occurring Radioactive Materials (NORM) i.e. ²²⁶Ra, ²²⁸Ra and ⁴⁰K in the east coast of Peninsular Malaysia Exclusive Economic Zone (EEZ) was carried out as part of the national marine environment project. Sixteen marine sediment cores from selected locations within the EEZ were collected for determination of NORM activity concentrations using high-purity germanium (HPGe) gamma spectrometer. From the measurement, the activity concentration of ²²⁶Ra, ²²⁸Ra and ⁴⁰K is ranged from 16 ± 4 Bq/kg to 46 ± 6 Bq/kg (total mean 30), 28 ± 7 Bq/kg to 87 ± 11 Bq/kg (total mean 56) and 171 ± 33 Bq/kg to 690 ± 89 Bq/kg (total mean 420), dry wt., respectively. The activity concentrations of radionuclides in most of the core were quite uniform suggesting that there were thorough vertical mixed of sediment throughout the core. The results obtained were also in good agreement with those previous reported from other countries in the region and therefore can be used to enhance present radioactivity database. The calculated external hazard values were ranged from 0.25 to 0.51 with the mean of 0.38 (less than unity) showed little risk of external hazard to the workers handling the sediments and it was likely low level of the mainland natural gamma-radiation in the east coast of Peninsular Malaysia.     

State-of-the-art of NORM nuclide determination in samples from oil and gas production: Validation of potential standardization methods through an interlaboratory test programme

Gas and oil companies frequently encounter build up of Naturally Occurring Radioactive Material (NORM) in their production and processing facilities. In the Netherlands NORM is subject to strict national regulations and, consequently, installations have to be screened on a regular basis. The availability of accurate and reliable NORM sampling and analysis techniques is therefore essential. A number of years ago, the Nederlandse Aardolie Maatschappij B.V. (NAM) actively initiated an investigation on analysis techniques for NORM samples from gas and oil companies. Within this framework, Shell Research Amsterdam organized a four-stage interlaboratory test programme in which representative samples of increasing complexity were analyzed by a number of Dutch institutes. Whereas a large spread in results was observed in the first stage, results in the last stage deviated less than ±10% from the values certified by an independent referee institute, even for comple, sludge samples. It was found that in particular the use of different values for the -yields and branching ratios amongst the institutes was responsible for the initial spread.     

Assessment of NORM at diamond cement factory and its effects in the environment

Preliminary studies have been conducted into the impact of NORM (naturally occurring radioactive materials) on the environment and the public from the operational activities of Diamond Cement factory in Ghana. Both water and soil samples were collected and their activities measured using gamma spectrometry. The annual effective dose was found to vary from 0.022 to 0.186 mSv with an average of 0.094 ± 0.041 mSv for soil samples. That of the water samples varied from 0.094 to 0.287 mSv with an average of 0.179 ± 0.080 mSv. The average value of the equivalent dose of the soil samples was found to be lower than the world average soil annual equivalent dose of 0.7 mSv.     

Determination of naturally occurring radioactive materials (NORM) in formation water during oil exploration

The present study is conducted, in order to contribute to a future waste management policy related to the presence of technologically enhanced natural occurring radioactive material (TENORM) in Iran petroleum industry. Samples were collected from offshore oil company for analysis of ²³⁸U, ²³⁵U, and ²³²Th series in produced waters. The activities of samples were determined by high-purity germanium detector, well for lowlevel activity γ-spectrometry. The results have shown that, ²²⁶Ra concentration ranges from 5.26 Bq/L to 27.93 Bq/L. Also the total activity in produced water is in the range of 16–840 Bq/L were mainly due to enhanced levels of dissolved ²²⁶Ra, ²¹⁴Pb, ²¹⁴Bi ions. Also, enhanced dissolution of elements such as radium by increasing of salinity, result in higher concentration of NORM in old oil region. Measured values are above EPA regulation (40 CFR 141055) & aqueous Derived Release Limit (DRL) of Canadian guideline for the management of (NORM). Therefore produced water has to dispose in pits which have to design for decrease the environmental effects. Also according to this study, re-injection of produced water in to abandon well of Iran Offshore Oil Company in Persian Gulf, have preference over discharging to the pits.     

Analytical methods for the characterization and the leachability evaluation of a solid waste generated in a phosphoric acid production plant

Naturally Occurring Radioactive Materials (NORM) are present in the environment and can be concentrated by technical activities, particularly those involving natural resources. These NORM deposits are highly stable and very insoluble under environmental conditions at the earth's surface. However reducing or oxidant conditions or pH changes may enable a fraction of naturally occurring radionuclides to eventually be released to the environment. In this paper the analytical methods to determine the chemical and radiochemical composition of a solid waste generated in an acid phosphoric production plant was shown. The sample, analysed by gamma spectrometry and radiochemical methods, contained ²¹⁰Pb and ²¹⁰Po and a high activity concentration of uranium isotopes but it shows a very low quantity of ²²⁶Ra. Also a sequential extraction method consisting of five operationally-defined fractions was used to evaluate the leachability of uranium isotopes, ²¹⁰Pb and ²¹⁰Po. The average leaching potential observed in the sample is 97.6% for ²³⁸U, 93.2% for ²¹⁰Pb and 82.4% for ²¹⁰Po. Moreover the results show that ²¹⁰Pb and ²¹⁰Po are leachable under only extreme conditions, whereas uranium is very more soluble.     

Direct determination of 226Ra in NORM/TENORM matrices by gamma-spectrometry

Summary The main shortcoming with the procedure to determine ²²⁶Ra in a gamma spectrum of an environmental sample by means of the ²¹⁴Bi and ²¹⁴Pb photopeaks is the likelihood of ²²²Rn leakage from the sample counting vial. An option to make such determination is to disregard the ²²⁶Ra gamma-contributions to the spectrum, other than 186.2 keV (3.5%), subtracting the ²³⁵U contribution to the ²²⁶Ra+²³⁵U peak at 186 keV. The use of this option to determine directly ²²⁶Ra activity concentrations in environmental samples and in NORM/TENORM matrices will be presented and discussed.     

Leachability of naturally occurring radioactive materials

Summary Naturally occuring radioactive materials (NORM) are present in the environment and can be concentrated by technical activities, particularly those involving natural resources. These NORM deposits are highly stable and very insoluble under environmental conditions at the earth's surface. However, reducing or oxidant conditions or pH changes may enable a fraction of naturally occurring radionuclides to eventually be released to the environment. In this paper the leachability of²¹⁰Pb and²¹⁰Po was determined in three samples coming from a refractories production plant (dust, sludge, finished product), in one dust sample from a steelwork and in one ash sample coming from an electric power station. A sequential extraction method consisting of five operationally-defined fractions was used. The average leaching potential observed in the samples from the refractory industry is very low (mean values: 5.8% for²¹⁰Pb and 1.7% for²¹⁰Po). The²¹⁰Pb and²¹⁰Po leachability increases for the ash sample coming from an electric power plant using carbon (17.8% for²¹⁰Pb and 10.0% for²¹⁰Po); for the dust sample coming from a steelwork, the percent soluble fraction is 41.1% for²¹⁰Pb and 8.5% for²¹⁰Po. For all samples the results obtained show that²¹⁰Pb is slightly more soluble than²¹⁰Po.     

Validation of MCNP volume efficiency calculation for gamma spectrometric assay of large NORM samples

Gamma spectrometric assay of large samples of different types are a very common practice. The total efficiency for standard ¹⁵²Eu and large NORM samples were simulated using MCNP code and experimentally validated in this work. The simulation was performed for large cylindrical samples of different diameters and heights at different detector–sample spacings. The simulation results agreed with the experimental ones. Thus, this study has demonstrated that MCNP calculation provides a useful tool to determine the volume efficiency correction factor.     

Comparison of background gamma-ray spectra between Los Alamos, New Mexico and Austin, Texas

Background counts in gamma-ray spectrometry are caused by a variety of sources. Among these are naturally occurring radioactive materials (NORM) in the environment, interactions from cosmic radiation, and contamination within the laboratory. High-purity germanium detectors were used to acquire long background spectra in Los Alamos, NM (elevation ~7,300 feet) and Austin, TX (elevation ~500 feet). This difference in elevation has a sizeable effect on background spectra due to cosmic interactions, such as (n,n′) and (n,γ). Los Alamos also has a fairly high NORM concentration in the soil relative to Austin, and this gives way to various spectral interferences. When analyzing nuclear forensics samples, these background sources can have non-trivial effects on detection limits of low-level fission products. By accurately determining the influence that elevation and environment have on background spectra, interferences within various laboratory environments can be more accurately characterized.     

Measurement of naturally occurring radioactive materials (NORM) in beach sand minerals using HPGe based gamma-ray spectrometry

This paper discusses the measurement of naturally occurring radioactivity materials (NORM) in beach sand minerals using high resolution gamma spectrometry. In India, the beach sand minerals of economic interest from coastal Kerala, Tamil Nadu and Orissa are enriched with NORM due to the occurrence of monazite deposits and heavy minerals such as zircon, ilmenite, magnetite, garnet, rutile etc. Since many of these ores are rich in ²³²Th and other radio elements, certification of radioactivity levels has become mandatory in recent years. The average activity concentrations of ²²⁶Ra in zircon, rutile and garnet were 3,531, 1,134 and 17 Bq kg^?1, respectively. The average activity concentration of ²³²Th observed in zircon, rutile and garnet were 618, 454 and 64 Bq kg^?1, respectively. Concentration of ²²⁶Ra, ²³²Th, and ⁴⁰K in ilmenite ore ranged from 17.6–444 Bq kg^?1, 80.4–1971 Bq kg^?1 and ≤5.5–25.0 Bq kg^?1, respectively.     

First proficiency test for the determination of NORM in contaminated soil from the oil field

The Atomic Energy Commission of Syria (AECS), in cooperation with the Arabic Atomic Energy Agency (AAEA), has initiated the first proficiency test exercise for the determination of naturally occurring radioactive materials (NORM) in contaminated soil from the oil field. The soil sample was collected from one of the most highly radioactively contaminated lagoons with production water in the Syrian oil fields, which was then prepared, characterised and certified according to a standard procedure. Samples were dispatched to laboratories from eight Arab countries; Kuwait, Egypt, Yemen, Tunisia, Jordan, the Kingdom of Saudi Arabia, Libya and Syria. The results were evaluated using three statistical criteria; z-score, the U _test score and the relative bias. These statistical methods were used to evaluate the performance of each laboratory, in addition to the overall evaluation for each radionuclide. This evaluation has indicated that 57% and 86% of the results passed the criteria set for precision and accuracy applied for this test in relation to ²²⁶Ra and ²²⁸Ra, respectively. These two radionuclides are considered to be the most important radionuclides in the oil industry.     

Study of naturally occurring radioactive material (NORM) in top soil of Punjab State from the North Western part of India

The concentration levels of ²³⁸U, ²³² Th, ⁴⁰K and ¹³⁷Cs in top soils of State of Punjab located in the North Western part of India were measured using conventional low background gamma ray spectrometric setup as well as Compton suppressed gamma ray spectrometric setup. The radioactivity level of ²³⁸U and ²³²Th was found to vary between 15 Bq/kg and 27 Bq/kg and between 16 Bq/kg and 57 Bq/kg respectively. The radioactivity level of ⁴⁰K was found to vary between 266 Bq/kg and 799 Bq/kg. The mean radioactivity level of the NORM in general was found to be similar to what is expected as a result of their normal abundance.     

The use of energy information in plastic scintillator material

Plastic scintillator material is often used for gamma-ray detection in many applications due to its relatively good sensitivity and cost-effectiveness compared to other detection materials. However, due to the dominant Compton scattering interaction mechanism, full energy peaks are not observed in plastic scintillator spectra and isotopic identification is impossible. Typically plastic scintillator detectors are solely gross count detectors. In some safeguards and security applications, such as radiation portal monitors for vehicle screening, naturally-occurring radioactive material (NORM) often triggers radiation alarms and results in innocent or nuisance alarms. The limited energy information from plastic scintillator material can be used to discriminate the NORM from targeted materials and reduce the nuisance alarm rate. An overview of the utilization of the energy information from plastic scintillator material will be presented, with emphasis on the detection capabilities and potential limitations for safeguards and security applications.     

Preconcentration and separation of <Superscript>99</Superscript>Tc in groundwater by using TEVA resin

An effort has been made to optimize the counting time for low-level measurement of naturally occurring radioactive material (NORM) by considering the standard deviation between the activity values of different photopeaks and counting error. It is observed that at lower counting time, relative standard deviation (RSD) varies randomly, but attains a gradual trend with increasing time and also comes closure to the counting error. Therefore minimum counting time for low-level NORM measurement of ²³⁸U and ²³²Th would be the time required to stabilize the RSD values.     

Determination of macroconstituents and trace elements in naturally occurring radioactive material in oil exploration waste products

Naturally occurring radioactive materials (NORM) contain radionuclides, such as radium, thorium, and uranium. The existence of NORM remains an issue for oil and gas exploration because once the material becomes concentrated through technological activity, it becomes a radioactive contamination hazard or a radioactive waste. Pipes and tanks used to handle large volumes of produced water at some oil-field sites are coated with scale deposits that contain high levels ²²⁶Ra, ²²⁸Ra and ²¹⁰Pb. Experiments were conducted using thermal and epithermal neutron activation analysis and Compton suppression for the determination of macroconstituents and trace elements in the radioactive scale sample.     

“Green chemistry” – a new paradigm for the basic organic chemical industry

An analysis is given for the major existing problems in the manufacture of organic chemicals and motor fuels related to exhaustion of natural raw materials and the ecological deterioration of the environment. These problems may be solved to a considerable extent by applying advances in green chemistry. The promise and advantages of employing new microbiological technologies to yield valuable organic products and alternative fuels are examined.     

Removal of natural uranium from water produced in the oil industry using Algerian bentonite

Batch sorption experiments have been carried out to remove natural uranium (NORM) from water obtained together with crude oil and natural gas, using Algerian bentonites. The effect of some important factors such as S/L ratio, pH, initial concentration, particle size was evaluated and a kinetic study performed. The value of the distribution coefficient (K _d) at equilibrium for natural uranium varied from 30 to 600 cm³·g⁻¹ and 50 to 1100 cm³·g⁻¹ (∼10% margin error) using natural bentonite and drilling bentonite, respectively. The isotherms showed that the data are consistent with both Freundlich and Langmuir models.     

A Single-wavelength NIR-triggered Polymer for in situ Generation of Peroxynitrite(ONOO~–) to Enhance Phototherapeutic Efficacy

Phototherapies including photodynamic therapy(PDT) and photothermal therapy(PTT) are the most promising and non-invasive cancer treatments. However, the efficacy of mono-therapy of PDT or PTT is often limited by the phototherapeutic defects such as low light penetration depth of photosensitizers and insufficiency of photothermal agents. Peroxynitrite(ONOO~-) has been proved to be an efficient oxidizing and nitrating agent that involves in various physiological and pathological processes. Therefore, ONOO~-produced in tumor site could be an effective treatment in cancer therapy. Herein, a novel cyanine dye-based(Cy7) polymer nanoplatform is developed for enhanced phototherapy by in situ producing ONOO~-. The Cy7 units in the nanoparticles can not only be served as the photosensitizer to produce reactive oxygen species(ROS) including singlet oxygen and superoxide anion for PDT, but also be used as a heat source for PTT and the release of NO gas from N-nitrosated napthalimide(NORM) at the same time. Since NO can react quickly with superoxide anion to generate ONOO~-, the enhanced phototherapy could be achieved by in situ ONOO~-produced by PCy7-NO upon exposure to the near infrared(NIR) light. Therefore, the NIRtriggered Cy7-based nanoplatform for ONOO~--enhanced phototherapy may provide a new perspective in cancer therapy.