The enrichment meter principle provides a nondestructive measurement of the ²³⁵U fraction of uranium-bearing items. Sampling is not required and no waste is generated, minimizing exposure to hazardous materials and resulting in reduced sampling error.

Use of a low resolution detector (e.g., NaI detector) to measure uranium with ²³⁵U fraction approximately 10 % which is contained in a thin-walled container can provide a rapid (typically 100 s), easily portable measurement system with precision of 0.6 % and bias of less than 1 %.

Use of a high resolution detector (e.g., high-purity germanium) can provide measurement with a precision better than 0.2 % and a bias less than 1 % within a 300-sec measurement time when measuring uranium with ²³⁵U fraction in the range of 0.711 % to 4.46 % which is contained in thin-walled containers.

In order to obtain optimum results using this method, the chemical composition of the item must be well known, the container wall must permit transmission of the 185.7 keV gamma ray, and the uranium-bearing material within the item must be infinitely thick with respect to the 185.7 keV gamma ray.

Items must be homogeneous with respect to both ²³⁵U fraction and chemical composition.

The uranium-bearing materials in the measured items and calibration reference materials used for calibration must fill the detector field of view.

When measuring items, using low-resolution detectors, in thin-walled containers that have not reached secular equilibrium, either the method should not be used, additional corrections should be made to account for the age of the uranium, or high-resolution measurements should be performed.

The method is typically used as a verification technique, not to establish enrichment.