Branch Technical Position on Concentration Averaging and Encapsulation

The regulatory requirements for licensing a low-level waste (LLW) disposal facility describe a system for classifying low-level radioactive waste for near-surface disposal. Classification of LLW is based on the concentrations of certain radionuclides, and 10 CFR 61.55(a)(8) specifically allows for averaging of concentrations in determining the waste class. The Branch Technical Position (BTP) on Concentration Averaging and Encapsulation expands on those regulatory requirements by describing acceptable averaging methods that can be used in classifying waste.


10 CFR Part 61, "Licensing Requirements for Land Disposal of Radioactive Waste," provides licensing procedures, performance objectives, and technical requirements for the issuance of licenses for the land disposal of low-level radioactive waste (LLW). Four performance objectives, including protection of an inadvertent intruder into the waste disposal site, define the overall level of safety to be achieved by disposal (*). Intruder protection is provided in part by the waste classification concentration limits in 10 CFR § 61.55, which are designed to ensure that an inadvertent intruder is not exposed to unsafe levels of radiation. All LLW must be classified in accordance with the waste classification tables in 10 CFR § 61.55. Concentrations of radionuclides that are used to determine the waste classification may be averaged over the volume or weight of the waste, in accordance with 10 CFR § 61.55(a)(8).

The staff has published guidance that defines acceptable approaches for such concentration averaging. In 1983 the NRC issued, "Low-Level Waste Licensing Branch Technical Position on Radioactive Waste Classification", one of the first guidance documents supporting Part 61. The waste classification technical position paper describes overall procedures acceptable to NRC staff which may be used by licensees to determine the presence and concentrations of the radionuclides listed in 61.55, and thereby classifying waste for near-surface disposal.

In 1995 the NRC revised, in part, the 1983 "Low-Level Waste Licensing Branch Technical Position on Radioactive Waste Classification." The initial 1983 guidance established a technical position on radioactive waste classification. The initial guidance included a section, "Concentration Volumes and Masses," that provided guidance to waste generators on the interpretation of 10 CFR 61.55(a)(8), as it applies to a variety of different forms and types of low-level waste. The 1995 Branch Technical Position on Concentration Averaging and Encapsulation (CA BTP), expands on, further defines, and replaces the guidance which was provided in Section C.3 of the original 1983 technical position. The 1995 Technical Position represents acceptable methods by which specific waste streams or mixtures of these waste streams may be classified.

In 2007 the NRC staff performed a strategic assessment of the NRC's regulatory program for LLW. The staff undertook this effort in recognition of significant new and emerging LLW disposal issues. The strategic assessment identified a need to update the CA BTP. The CA BTP has the potential to increase the flexibility of disposal of certain types of LLW, particularly sealed sources, ion exchange resins, and irradiated hardware. The strategic assessment stated that the staff will use risk-informed approaches and knowledge that were not available when the BTP was developed and last updated (in 1995).

In SECY-10-0043, the staff provided the Commission with an analysis of issues related to LLW blending. In the Staff Requirements Memorandum (SRM) for SECY-10-0043 (SRM-SECY-10-0043), the Commission directed the staff to revise the blending position in the CA BTP to be risk-informed and performance-based. With this decision, the staff was in a position to update the entire CA BTP, not only addressing blending, but also the remainder of the CA BTP topics that addressed mathematical averaging of radioactivity concentrations. Revising the CA BTP aligned with the NRC's position of moving towards a risk-informed performance-based regulatory approach. Refer to the NRC public website on LLRW blending for more information on this topic.

The final version of the CA BTP was published in February 2015. Volume 1 (ML12254B065) is the actual guidance document and Volume 2 (ML12326A611) contains responses to stakeholder comments and the technical basis.

NRC staff anticipates questions regarding implementation of the BTP; therefore, staff will post questions (with answers) as they are received. The current list of questions/answers can be found in ADAMS (ML16237A374). If you have a question regarding implementation of the BTP, then send it to Maurice Heath at

(*) The others are protection of the general population from releases of radioactivity; protection of individuals during the operation of the facility (as opposed to after the facility is closed) and stability of the disposal site.

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Page Last Reviewed/Updated Wednesday, December 27, 2017