Stress analysis and testing of the outer capsule design for the Strontium Heat Source Development Program

Abstract

The objective of the Strontium Heat Source Development Program is to 90 obtain the data needed to license SrF^ heat sources-specifically the 90 SrFp capsules produced in the Waste Encapsulation and Storage Facility (WESF) at Hanford. Toward this end, a high integrity outer capsule has 90 been designed to replace the present outer capsule of the WESF SrFp capsule. This report describes the proposed design of a Hastelloy S® outer capsule which features a mechanical interlock type of end closure. Qualification testing requirements are outlined, and stress analyses and developmental tests are described. These tests were performed on AISI-1018 steel stand-in capsules, and included both external pressure and impact tests. The external pressure tests showed that stress calculations seriously overestimated the pressure capability of the outer capsule. Possible reasons for the lack of agreement between the tests and the analyses are evaluated. The stress analyses and test results indicate that the proposed outer capsule will meet the heat source qualification requirements. Future tests will be conducted to experimentally verify that the Hastelloy S outer capsule in an aged condition meets the structural integrity requirements. Hastelloy is a trade name of the Stellite Division, Cabot Corporation.

Collapse of experimental capsules under external pressure

“…After adjustments to correct for the unexpected yield behavior of the tube material, the predicted pressure-deflection trends were found to follow the experimental data. Simonen (1979). Nuclear Regulatory Commission regulations require that the capsule sustain an external pressure of 1000 bars (14,500 psi).…”