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Title: Flow excursion time scales in the advanced neutron source reactor

Flow excursion transients give rise to a key thermal limit for the proposed Advanced Neutron Source (ANS) reactor because its core involves many parallel flow channels with a common pressure drop. Since one can envision certain accident scenarios in which the thermal limits set by flow excursion correlations might be exceeded for brief intervals, a key objective is to determine how long a flow excursion would take to bring about a system failure that could lead to fuel damage. The anticipated time scale for flow excursions has been examined by subdividing the process into its component phenomena: bubble nucleation and growth, deceleration of the resulting two-phase flow, and finally overcoming thermal inertia to heat up the reactor fuel plates. Models were developed to estimate the time required for each individual stage. Accident scenarios involving sudden reduction in core flow or core exit pressure have been examined, and the models compared with RELAP5 output for the ANS geometry. For a high-performance reactor like the ANS, flow excursion time scales were predicted to be in the millisecond range, so that even very brief transients might lead to fuel damage. These results should prove useful whenever one must determine the time involved inmore » any portion of a flow excursion transient.« less
Authors:
Publication Date:
OSTI Identifier:
78569
Report Number(s):
CONF-950904--4
ON: DE95009181; TRN: 95:016185
DOE Contract Number:
AC05-84OR21400
Resource Type:
Conference
Resource Relation:
Conference: 7. international topical meeting on nuclear reactor thermal-hydraulics (Nureth-7), Saratoga Springs, NY (United States), 10-15 Sep 1995; Other Information: PBD: [1995]
Research Org:
Oak Ridge National Lab., TN (United States)
Sponsoring Org:
USDOE, Washington, DC (United States)
Country of Publication:
United States
Language:
English
Subject:
22 NUCLEAR REACTOR TECHNOLOGY; NEUTRON SOURCE FACILITIES; EXCURSIONS; SYSTEM FAILURE ANALYSIS; TWO-PHASE FLOW; FLOW RATE; FUEL PLATES