Sequential multi-nuclide emission rate estimation method based on gamma dose rate measurement for nuclear emergency...

Area of Science:

• Nuclear engineering
• Environmental science
• Radiological assessment

Background:

• Accurate source term estimation is critical for nuclear accident emergency response.
• The composition and emission rate of radioactive releases are often unknown.
• Existing methods may struggle with uncertainty and negative estimations.

Purpose of the Study:

• To develop a robust sequential method for reconstructing the source term of multiple-nuclide releases.
• To improve the accuracy and efficiency of emission and composition assessment using gamma dose rate data.
• To address challenges like unknown a priori information and negative estimations in algorithms.

Main Methods:

• A fully sequential method based on a regularized weighted least square problem.
• Incorporation and dynamic updating of a priori nuclide ratios into the background error covariance (BEC) matrix.
• Suppression of negative estimations using artificial zero-observations.

Main Results:

• Successful reconstruction of radionuclide emission rates and their uncertainties.
• Demonstrated effectiveness of the method in twin experiments using the JRodos system.
• Validation of the impact of accurate a priori ratios on analysis speed and data requirements.

Conclusions:

• The proposed method provides a reliable way to assess nuclear accident source terms.
• Effective suppression of negative values enhances performance, especially with limited prior information.
• The method's efficiency is significantly improved by accurate a priori nuclide ratio data.