Pipe break testing of primary loop piping similar to the Department of Energy's new production reactor-heavy water reactor

This paper provides information about and results from specific tests completed at Oak Ridge National Laboratory (ORNL) in support of the Department of Energy's (DOE's) new production reactor-heavy water reactor (NPR-HWR) program. The paper also provides detailed analytical studies completed by Battelle Columbus Laboratory. All of this information is presented in a demonstration that the primary piping of the NPR-HWR, with its relatively moderate temperature and pressure should not suffer an instantaneous double-ended guillotine break (DEGB) under design basis loadings and conditions. The first ORNL test series obtained pipe crack extension data representative of large dynamic loads applied to a flawed stainless steel 316LN pipe weldment. The results of that testing were reviewed by a special Piping Integrity Review Group (PIRG) established by DOE. Members of this group are identified in this paper. The PIRG review comments were such as to necessitate a second series of tests. This paper provides results of that second series of pipe tests. An aged section of 304 stainless steel pipe, obtained from the C-reactor at Savannah River, was subjected to large fully reversed cyclic bending loads. An initial flaw size was based on leakage flow testing at prototypic NPR-HWR pressure and temperature. The detectable leakage flaw was cycled in bending at large loads for 40 cycles. The members of the PIRG assessed these results together with analytic work by Battelle and stated that, provided the caveats cited in this paper are in force, the following conclusion is applicable: • For DOE low-pressure (≤1·72 MPa), low-temperature (100°C) reactors with austenitic stainless steel piping, the DEGB should not be a design basis condition.