(57d) Spray Releases from Pressurized Piping in Nuclear Facilities

An aerosol release from a leak or process piping failure is an important accident scenario to consider when performing nuclear facility safety analyses. Across the Department of Energy complex, DOE-HDBK-3010-94 has long been the source for acceptable methodologies to analyze various postulated events involving aerosol releases. It recommends bounding values of release fraction and airborne release fraction to be used to determine the source term from various phenomenologies. A recent independent technical review of DOE-HDBK-3010-94 identified some questions regarding the conservatism inherent in its recommended approaches. Concurrent with that review, Pacific Northwest National Laboratory (PNNL) embarked on a multi-year, multi-scale test program to measure aerosol releases from pressurized piping to support accident analyzes for the Waste Treatment and Immobilization Plant (WTP) on the Hanford site. The program examined the impact of an array of physical parameters that play a role in aerosol formation and transportation when a spray leak or release occurs. The test approach and key results from the PNNL test program will be discussed within the context of informing facility safety analyses.