1、 American National Standard ANSI/HPS N13.12-2013 Surface and Volume Radioactivity Standards for Clearance Approved: May 6, 2013 American National Standards Institute, Inc. Published by Health Physics Society 1313 Dolley Madison Blvd. Suite 402 McLean, VA 22101 Copyright 2013 by the Health Physics So
2、ciety. All rights reserved. No part of this publication may be reproduced in any form, in an electronic retrieval system or otherwise, without prior written permission of the publisher. Printed in the United States of America ANSI/HPS N13.12-2013 iii This standard was developed under the authority o
3、f the Health Physics Society Accredited Standards Committee (ASC) N13, Radiation Protection. The Working Group responsible for this standard had the following members: William E. Kennedy, Jr., Chairperson Dade Moeller Safety Series No. 89; 1988; and International Basic Safety Standards for Protectio
4、n against Ionizing Radiation and for the Safety of Radiation Sources, Safety Series No. 115, 1996; International Atomic Energy Agency, Vienna. 2Where radiation dose in this context is the total effective dose. Radiation dose, in general, is the energy deposited per unit mass. The SI unit for total e
5、ffective dose is joule per kilogram, given the special name sievert (Sv). The conventional unit for total effective dose in the United States is the rem, which equals 0.01 joule per kilogram. ix international recommendations for clearance of items or materials that contain levels of radioactive mate
6、rials within authorized practices from further radiological control. In response to the IAEA recommendations, the U.S. federal agencies concerned with controlling radiation exposures requested that the writing group for this standard be reformed to determine whether it would be possible to harmonize
7、, or bring into accord, the 1999 version of this standard and the IAEA recommendations. The writing group was reformed in 2005, and this revised standard is a result of the harmonization effort. It is noted that this standard focuses only on clearance, and not on exemption and exclusion, as included
8、 in the IAEA recommendations. It is also noted that the IAEA recommendations are based on modeling that uses the dosimetric recommendations of the International Commission on Radiological Protection (ICRP) found in their publication 60 (ICRP 1991). The writing group considered using the dosimetric r
9、ecommendations from the newer ICRP Publication 103 (ICRP 2007) but concluded that, lacking scenario-specific dose conversion factors, it was not possible at this time. The purpose and scope of this standard are provided in Section 1.0 and basic definitions are provided in Section 2.0. Section 3.0 co
10、ntains the basic dose criterion (in terms of the primary dose standard for clearance) and the derived screening levels (in terms of the activity per unit surface area or mass). Section 4.0 provides information useful in the implementation of this standard and covers a wide variety of topics includin
11、g the role of process knowledge, instrument selection, surface versus volume measurements, summing radionuclide fractions, concentration averaging, removable radioactivity levels, radiological measurements, representative sampling and testing, and quantitative versus qualitative measurement techniqu
12、es. Section 5.0 provides a discussion of records, and Section 6.0 provides the references cited in this standard. A more complete discussion of the details and technical basis for the harmonization of the previous version of this standard with the IAEA recommendations for clearance are found in Anne
13、x A. Annex B contains a discussion of as low as reasonably achievable (ALARA) considerations for clearance. A comparison of the derived screening levels with other guidance is provided in Annex C. Annex D contains informative references supporting the information in Annexes A, B, and C. Suggestions
14、for improvement of this standard are welcome. Send suggestions to the Health Physics Society, 1313 Dolley Madison Blvd., Suite 402, McLean, VA 22101. AMERICAN NATIONAL STANDARD ANSI/HPS N13.12-2013 1 Surface and Volume Radioactivity Standards for Clearance 1.0 Purpose and Scope 1.1 Purpose This stan
15、dard is intended to provide guidance for protecting human health from radiation exposure by specifying a primary radiation dose criterion and derived screening levels for the clearance of items or materials that could contain radioactive materials, in a manner consistent with the recommendations of
16、the International Atomic Energy Agency (IAEA) on clearance. 1.2 Scope This standard applies to the clearance of items and materials from areas controlled to protect individuals from exposure to radiation or radioactive material during or after operations. This standard establishes a primary radiatio
17、n dose criterion and derived screening levels for surface and volume radioactivity for groups of radionuclides. The following are not included in the scope of this standard: 1. naturally occurring radioactive materials (NORM) in bulk; 2. radioactive materials in or on persons, including 40K in the b
18、ody; 3. release of a licensed or regulated site or facility; 4. radioactive materials on or in foodstuffs; 5. release of land or soil intended for agricultural purposes; 6. clearance issues related to national defense or security; 7. process gases and liquids, including those discharged in accordanc
19、e with federal or state license requirements; 8. radioactive material in transport in accordance with Department of Trans-portation, U.S. Nuclear Regulatory Commission (USNRC), or U.S. Depart-ment of Energy (DOE) regulations; and 9. radioactive materials at concentrations or quantities governed by r
20、egulations or exemption or exclusion. This clearance standard is not intended as a substitute for radiological criteria for decom-missioning or for intervention criteria during cleanup projects. This standard provides screening levels, which are protective of the public health, for the clearance of
21、items or materials. 2.0 Definitions The following basic definitions are provided to aid in the understanding and interpre-tation of this standard. ALARA: The acronym means As Low As is Reasonably Achievable. ALARA is not a standard of care; it is the process through which the Optimization Principle
22、of the radiation protection philosophy is addressed. ALARA means making every reasonable effort to maintain exposures to radiation as far below dose limits as is practical and consistent with the authorized purpose of the practice, taking into account the state of technology, the economics of improv
23、ements in relation to the technology, the economics of improvements in relation to benefits to worker and public health and safety, and other societal and socioeconomic consi-derations. Background: Background radiation includes both natural and anthropogenic sources. Natural background radiation sou
24、rces include primordial radionuclides (i.e., radio-nuclides belonging to the three radioactive decay series headed by 238U, 235U, 232Th),40K, and 87Rb cosmogenic radio-nuclides (i.e., radionuclides produced by interactions of cosmic nucleons with target atoms in the atmosphere or in the earth includ
25、ing 14C, 3H, 7Be, and 22Na), and cosmic radiation (i.e., radiation from the secondary particles, mostly high-energy muons and electrons, produced by interactions of charged particles, primarily protons, from extraterrestrial sources with the Earths atmosphere). Anthropogenic background radiation and
26、 radioactive material in the environment includes human-made or human-induced sources such as nuclear fallout from previous weapons testing or significant accidents with major geographic impacts and industrial releases such as emissions from coal-fired combustion that are dispersed to the ANSI/HPS N
27、13.12-2013 2 environment. Naturally occurring radioactive material in bulk that has been tech-nologically enhanced is not considered background for purposes of this standard. Clearance: The removal of items or materials that contain or may contain residual levels of radioactive materials within auth
28、orized practices from further radiological control for radiation protection purposes. Committed Effective Dose: The dosimetric quantity formed by multiplying the time integral of the equivalent dose rate in a tissue or organ following an intake by the appropriate tissue weighting factor and then sum
29、ming the resultant products, as defined by the International Commission on Radiological Protection (ICRP 1991). Critical Group: A group of individuals in the population expected to receive the highest dose. Decay Series: The decay of a radionuclide (parent) producing a decay product (progeny) that i
30、tself is radioactive and subsequently undergoes radioactive decay, producing its own decay product. This process may be repeated several times with each succeeding radioactive decay product undergoing radioactive decay until a stable (i.e., nonradioactive) decay product is produced. The entire seque
31、nce from the original parent radionuclide through all of the succeeding decay products to the final stable decay product is a decay series. DQO: The acronym means Data Quality Objectives, which are an established set of qualitative and quantitative criteria, including acceptable tolerance levels, to
32、 specify the quality and quantity of data necessary to support a given decision (e.g., conformance with acceptable clearance screening levels). Effective Dose: Formed by weighting the equivalent dose in a tissue or organ by the tissue weighting factor, wT, and summing over the tissues or organs, as
33、defined by the International Commission on Radiological Protection (ICRP 1991). The equivalent dose to the whole body at a depth of 1.0 cm may be used as the effective dose for external exposures. Equivalent Dose: The product of the absorbed dose in a tissue or organ and the radiation weighting fact
34、or, wR,as defined by the International Commission on Radiological Protection (ICRP 1991). Exclusion: The designation by a regulatory authority that the magnitude or likelihood of an exposure is essentially unamenable to control through requirements of standards and such exposures are outside the sco
35、pe of standards (e.g., exposure from 40K in the body, from cosmic radiation at the surface of the earth, and from unmodified concen-trations of radionuclides in most raw materials). Exemption: The designation by a regulatory authority that specified uses of radioactive materials or sources of radiat
36、ion are not subject to regulatory control because the radiation risks to individuals and the collective radiological impact are sufficiently low. Ionizing Radiation: Includes alpha particles, beta particles, gamma rays, x-rays, and other particles capable of causing ionization of target materials. M
37、ay: The term may is used in this standard to identify elements of optional guidance potentially useful in interpreting and implementing the requirements of this standard. MQO:The acronym means Measurement Quality Objectives, which are an established set of performance criteria for a given measuremen
38、t method necessary to meet the established DQOs for a given clearance action. Process Knowledge: A collection of facts, information, and data characterizing or describing past or current processes or practices. Screening Level: Activity concentrations (for either surface or volume radioactivity) tha
39、t are designed to determine compliance with the primary dose criterion through comparison with radiation survey results. ANSI/HPS N13.12-2013 3 Shall: The word shall is used to identify mandatory elements of this standard needed for full implementation of the standard. Should: The word should is use
40、d to identify elements of guidance in this standard. If the guidance is not followed, technical equi-valency in outcome must be demonstrated in alternative manners. Site: A licensed or regulated location that includes one or more (1) facilities designated for the use of radioactive materials or radi
41、ation generating devices or (2) radiologically controlled or restricted areas. Surface Radioactivity: Radioactivity residing on or near the surface of items or materials that can be adequately quantified in units of activity per unit area. When an item or material (including structural components an
42、d shielding at nuclear reactors) has been exposed to neutron irradiation, or when an item or material could have cracks or interior surfaces allowing the distribution of radioactivity within the interior matrix, it is conservatively considered to be a volume source of radioactivity. Survey: A system
43、atic evaluation and documentation of radiological measure-ments with a correctly calibrated and operated instrument or instruments that meet the detection levels required by the objective of the evaluation. Technologically Enhanced Naturally Occurring Radioactive Material (TENORM): Naturally occurri
44、ng radioactive material disturbed or altered from natural settings or present in a technologically enhanced state due to past or present human activities and practices that could result in a relative increase in radionuclide concentrations, radiation exposures and risks to the public, and threat to
45、the accessible environment above background radiation levels. “Technologically enhanced” means that the radiological, physical, and chemical properties of the radioactive material have been altered. In comparing background radioactivity or radiation levels with TENORM, the definition does not provid
46、e a point of reference, such as a level equivalent to a multiple of background, because this could lead to situations in which a material not considered TENORM in a high-background area could become TENORM when relocated to a lower-background area. TENORM does not include radiation emanating from or
47、 radioactivity present in ores, rocks, soils, and materials containing uranium and thorium subject to regulations under the Atomic Energy Act (ANSI/HPS N13.53-2009). Total Effective Dose (TED): The sum of the effective dose (for external exposures) and the committed effective dose (for internal expo
48、sures) from exposures during a single year. Volume (or Volumetric) Radioactivity: Radioactive material residing in or throughout the volume of items or materials. Volume radioactivity can result from activation (e.g., through neutron irradiation) or from the penetration or absorption of radioactive
49、materials into porous materials, cracks, or on interior surfaces within the interior matrix of items or materials. A common example is wood that has absorbed fluids containing radioactive materials. 3.0 Dose Criteria and Derived Screening Levels The following section defines the primary (dose) and secondary screening (derived) criteria that comprise this standard. 3.1 Primary Dose Criterion The primary criterion of this standard is to provide for public health and safety to an average member of a critical group such that the dose shall be limited to 10 Sv/y (1.0 mrem/
