HPS - ANSI/HPS N13.53
Control and Release of Technologically Enhanced Naturally Occurring Radioactive Material (TENORM)
|Publication Date:||1 January 2009|
This standard specifies dose limits and release criteria for the management of material, products, and waste containing technologically enhanced naturally occurring radioactive material (TENORM), namely uranium and thorium. TENORM is used to differentiate radioactivity present in some materials and processes from NORM contained in nearly all materials of mineral origins. The radioactivity in TENORM is due to a few predominant radionuclides associated with two radioactive decay series, namely uranium-238 (238U) consisting of thorium-234m (234mTh), protactinium- 234m (234mPa), 230Th, radium-226 (226Ra), radon-222 (222Rn), lead-210 (210Pb), and polonium-210 (210Po); and the 232Th series consisting of 228Ra, 228Th, 224Ra, and 220Rn. In some situations, the actinium decay series, starting with 235U, may need to be considered as well, especially if 238U concentrations are elevated even at natural isotopic abundances. The major decay products of 235U include 231Th, 231Pa, actinium-227 (227Ac), 227Th, 223Ra, and 219Rn. The isotopic distribution of natural uranium is given as 48.9% for 238U, 48.9% for 234U, and 2.2% for 235U, in terms of activity. Potassium-40 (40K) is also included because in some instances it may be isotopically enriched. Annex A presents the radioactive decay schemes for the uranium and thorium series and potassium.
In defining the objective of this standard, it should be recognized that the demarcation between NORM and TERNORM is not always well delineated; often, an industry using or receiving materials may not be capable of distinguishing materials that are TENORM, or even materials that may be subject to existing federal or state regulations. Given that it is not possible to catalog a priori all situations involving the use of TENORM, the standard provides a common theme and information with which to recognize practices that may result in unnecessary radiation exposures to workers and the public and possibly have an impact on the environment. In considering a specific practice, the information provided in this standard should be used to seek technical and regulatory advice from qualified regulatory agencies or experts in the appropriate disciplines. In this context, the standard recommends that industries routinely monitor rule-making activities as emerging issues involving TENORM are addressed by federal or state agencies. Finally, the standard may be adopted by industries and organizations as guidance in foreign countries where there are no TENORM regulations or guidelines.
The criteria are contained in Section 2.0, and Annex B presents the basis for the recommended criteria. Also, the standard offers further guidance to facilitate its implementation. Annex C presents background information for recognizing and evaluating practices that may have potential impacts on the public, workers, and the environment. Annex D describes various options for managing TENORM and also includes supporting technical information. The guidance presented in Annexes C and D is informative and not part of the requirements or criteria presented in Section 2.0. Annex E presents normative and informative references cited throughout the standard.
The standard applies to practices that use, process, recycle or reuse, and distribute TENORM, including the generation and disposal of wastes that may result in making radioactivity more accessible to humans or the environment. Among others, practices of specific concern to this standard include home building using materials obtained from mining and mineral extraction spoils, overburden, and wastes or building homes on sites containing extraction spoils, overburden, aggregates, and wastes from mineral mining and oil and gas extraction. The quarrying of gravel and sand and their use as aggregates in construction material, such as cement, are excluded from this standard, but other materials with known elevated levels of NORM, such as some minerals, aggregates used in building construction, mining overburden and spoils, and sands, are covered by this standard.
The standard applies to consumer and industrial products that are known to contain TENORM. The intentional introduction of TENORM into products or materials with no benefit to their properties or functions is not approved by this standard. Regarding recycling, the standard does not approve practices whose only purpose is to dilute TENORM in a manner that constitutes disposal or processes leading to that intent.
This standard does not apply to NORM present in natural soils, rocks, and materials involving human activities that are generally regarded as common practices. Among others, such practices include materials used in scientific and research studies; engineering studies and applications; soil and geological samples used in site or material characterizations, research, and engineering studies; farming, including tilling and plowing; site grading; grave digging; and trenching or similar types of excavation or earth work.
The cultivation, distribution, and consumption of agricultural crops and foodstuffs that are known to contain NORM are not covered by this standard because such practices do not involve technological enhancement by definition. However, this exclusion does not apply to foodstuffs grown in TENORM whether as a product, waste, aggregate, or mixed with soils.
In the absence of regulatory requirements or guidance, the standard does not apply to industrial settings or activities involving the use of materials or products containing TENORM as long as such materials and products are used in their intended form and function and workers are provided a standard of care under Occupational Safety and Health Administration (OSHA) or Mine Safety and Health Administration (MSHA) regulations or other applicable regulatory provisions. This exclusion applies insofar as it shall be demonstrated that such practices and the associated standard of care for worker safety rendered under OSHA or MSHA regulations would result in a level of protection that is equivalent to this standard.
In considering the voluntary implementation of a TENORM management program, an acceptable approach may involve identifying relevant protective requirements for regulated materials (e.g., uranium and thorium under the Atomic Energy Act (AEA)), since radiation exposures and doses associated with TENORM are the same as those arising from other types of radioactive materials. Accordingly, it follows that radiation protection principles promulgated by existing federal or state regulatory programs for radioactive materials of other origins may be applied to TENORM as templates in developing safety programs, operating plans, and procedures for specific practices. Finally, other options, as possible long-term alternatives, may be to consider the use of materials with lower levels of TENORM or research leading to the use of substitute materials that are essentially free of NORM or have NORM at levels not likely to result in doses in excess of the provisions of this standard.
This standard may provide suitable guidance to federal or state agencies overseeing remediation projects where TENORM is the contaminant of concern, depending on the ownership and regulatory status of the property. For example, a federal or state agency might find the provisions of this standard protective and adopt it by reference. Other federal agencies, such as the U.S. Department of Energy (DOE) and the U.S. Nuclear Regulatory Commission (NRC), oversee other radiation cleanups involving TENORM or contaminants similar to TENORM (e.g., regulated source material). Accordingly, this standard offers relevant guidance over a broad range of practices and remediation projects involving TENORM.
Finally, the standard does not address issues associated with the linear, no threshold radiation dose response hypothesis; they are being addressed by radiation standard-setting organizations and regulatory agencies. However, its use is acknowledged because it represents a prudent approach in protecting workers and the public health until more definitive scientific information becomes available and an alternative hypothesis is proposed and adopted by regulatory agencies.