Project - Analytical substantiation of safe storage of Westinghouse spent nuclear fuel at ZNPP

At ZNPP, as at many NPPs around the world, there is a lack of space for SNF storage in at-reactor spent fuel pools. In order to solve this problem, it is typical to use additional SNF management systems, including dry storage of SNF, which was stored for a certain time in the spent fuel pools, at the NPP industrial site in special containers. These containers provide efficient of SFA decay heat removal and adequate biological shielding of NPP personnel and the environment from radiation.

Currently, ZNPP uses fuel from two manufacturers - the Russian concern TVEL (TVS-M, TVS-A, etc.), and the American company Westinghouse (TVS-WR). The introduction of TVS-WR fuel assemblies at the Zaporizhzhya NPP began after the construction of ZNPP DSFSF, therefore, at first, only Russian-made fuel was considered in the safety analysis report (SAR). After the introduction of TVS-WR, the substantiation of possibility of its storage in the ZNPP DSFSF was made as annex to the SAR.

NT-Engineering, by order of the Argonne National Laboratory, has implemented the Project in support of substantiation of safe storage of Westinghouse spent nuclear fuel at ZNPP.

In order to comprehensively and fully substantiate the safety of storage of Westinghouse fuel at ZNPP DSFSF, such design basis accidents were analyzed that could lead to a threat of criticality occurrence, various damage to the SNF management system and/or violation of the geometry and integrity of the fuel itself.

Within the framework of this Project, criticality issues and the possibility of a self-sustaining chain reaction occurring during additional initiating events for spent nuclear fuel produced by Westinghouse, which were not considered in the storage facility safety analysis reports (SAR), were analyzed.

Based on the calculation model, an analysis of possibility of fuel systems criticality that may arise as a result of degradation of fuel basket and during BDBA associated with a fall from a great height, more than 9 m, as well as due to the influence of fires lasting more than 30 minutes, was made.

To perform calculations of parameters and developed models, the SCALE calculation complex was used, which, by order of the U.S. Nuclear Regulatory Commission, has been developing and modernizing by scientists from the Oak Ridge National Laboratory of the United States for more than twenty years. Since the release of the first version of SCALE in 1980, this software package is used extensively by many organizations, both in the US and around the world, to model fresh and spent fuel management systems and, in particular, nuclear fuel storage facilities.

The materials of the Project have been developed in full, in due time and in accordance with the current requirements of nuclear and radiation safety of Ukraine, which is confirmed by the Customer’s positive response.

Customer’s positive response (PDF)

Photo by “Energoatom”