Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Comparisons: Radiological Traceability Program (RTP)


The Radiological Traceability Program (RTP) is a Proficiency Testing (PT) program that establishes traceability for the Radiological and Environmental Sciences Laboratory (RESL), the Department of Energy’s (DOE) reference laboratory, to the National Institute of Standards and Technology (NIST).


The RTP provides an annual exchange of PT materials between NIST and RESL. It is designed to provide a mechanism for evaluating the ability of RESL scientists to prepare PT materials containing known activities of various radionuclides (Table 1), and to analyze materials of unknown activities in 6 matrices: air filters, vegetation, water, soil, synthetic urine, and synthetic feces.

Table 1. Radionuclides for the Radiological Traceability Program

Nuclides Category
Th-230, U-238, U-234, Pu-238, Pu- 239/240, Am-241, Np-237 Alpha Emitting Radionuclides
H-3, Sr-90 Beta Emitting Radionuclides
Cs-137, Cs-134, Co-60, Mn-54, Co-57, Zn-65 Gamma Emitting Radionuclides
I-125, I-131 Isotopically Pure Radionuclides

The objective of the Program is to conduct measurement traceability evaluations of the DOE RESL consistent with the ANSI N13.30, N42.22 and N42.23 standards. RESL is the designated reference laboratory for DOE and the Nuclear Regulatory Commission (NRC) Radiological Measurement Assurance Program (RMAP). As defined in ANSI N42.23-1996, RESL serves as a secondary reference laboratory to NIST and maintains direct traceability to NIST through the RTP. In this role, DOE has authorized RESL to prepare and distribute PT materials in a variety of sample matrices to laboratories that perform radiochemical analyses of environmental, bioassay, and other samples.

The RTP consists of two performance components:

  1. NIST prepares PT materials to be analyzed by RESL. RESL’s analytical results are evaluated and Reports of Traceability of Characterization of Materials Containing Radionuclides for each of the 6 matrices are issued.
  2. NIST performs verification measurements on PT samples prepared by RESL. The RESL’s values are compared with the experimental results generated by NIST and a Report of Traceability for Preparation of Performance Evaluation Material by RESL is issued.

Each result reported to NIST represents the activity added by NIST to the PT material, not the total activity contained in the sample. The natural background activity contained in a sample matrix is subtracted from all analytical measurements.

Created September 19, 2016, Updated February 22, 2021