Improved safety basis for liquid waste processing at BWXT

The operational cost of an overly conservative safety basis can be significant. BWX Technologies, Inc. (BWXT) recently upgraded the safety basis for the liquid waste treatment facility at its Lynchburg, Virginia manufacturing plant to remove excess conservatism and allow more efficient operation. The previous safety basis resulted in a maximum mass in the treatment process at 600 grams ²³⁵U. The revised safety basis being developed uses the nature of the process and the design of the equipment to establish limits. The analysis considers precipitation and extraction by organics as an upset condition in the start of the process and as a normal part of the process in the later steps. Each of the tanks were evaluated over a range of sediment densities and distributions. The analyses of individual tanks established the actual margin of safety in the process. The solidification and drying equipment were likewise evaluated. The revised safety basis has established mass limits larger than can be used based on other regulatory considerations. Discussions with the United States Nuclear Regulatory Commission (USNRC) are on-going regarding revision to existing license conditions which would allow fully utilizing the increased limits in the revised safety basis.