Risk-informed design changes for a passive cooling system

The failure probability of a passive decay heat removal system after a LOCA is evaluated as part of a risk-informed design process for a helium-cooled fast reactor. The system was modeled using RELAP5-3D. The epistemic uncertainties in input parameters as well as the epistemic model uncertainties in the code were assessed and propagated through the model using Latin hypercube sampling. The changes in the design that we investigated reduced the overall failure probability of the system by reducing the impact of the major contributor to the failure probability. Sensitivity analyses led to two unexpected results. First, the key factors affecting the system failure probability are the location of the thermal insulation (inside or outside the hot leg) and the uncertainty in the insulation thermal conductivity. Second, the heat transfer coefficient in the core is not as important as one might expect. Our results show that the heat transfer coefficient in the containment structures is more important. Different methods for sensitivity analysis were applied and gave consistent results.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Nuclear Science and Engineering.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2007

Author dc:creator

• Patalano, Giovanbattista

Advisor dc:contributor.advisor

• George E. Apostolakis.

• Nuclear Science and Engineering.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/44780

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/44780