Risk-Informed Safety Analysis for Accident Tolerant Fuels

Abstract

Accident tolerant fuels (ATFs) are being tested by different nuclear vendors and research organizations, and their introduction into the U.S light water reactor fleet is planned for the second half of the 2020s. Under the framework of the U.S. Department of Energy Light Water Reactor Sustainability (LWRS) Program, as part of the LWRS Risk-Informed Systems Analysis Pathway, research is being conducted at the Idaho National Laboratory (INL) to develop tools and methods that can help the industry to quantify the benefits from adopting ATF technology. In this paper we describe the developed risk-informed methodology including the safety analysis code improvements, and we present some results for selected accident scenarios. The developed methodology combines the INL state-of-the-art deterministic Best Estimate code RELAP5-3D and the probabilistic risk analysis tools RAVEN and SAPHIRE. The analyses are performed on a three-loop pressurized water reactor, simulating station blackout and large-break loss-of-coolant accidents and considering near-term ATFs or iron-chromium-aluminum and chromium-coated clads. Finally, we show how, applying our methodology, the new core damage frequency (CDF) can be assessed. The results indicate that the main benefit in introducing near-term ATFs is a significant reduction in hydrogen production during accident conditions. No significant CDF reduction was found.

Assessment of Modeling and Simulation Technical Gaps in Safety Analysis of High Burnup Accident-Tolerant Fuels

“…This model allows simulating the initiation of the metal-water reaction near 1000°C and auto-catalytic hydrogen production when the Zr cladding temperature goes over 1200°C (1477 K or 2200 °F). The RELAP5-3D metalwater reaction model was already updated to use two ATFs: Cr-coated Zr and FeCrAl (APMT) [19].…”

Hydrogen Isotopes Permeation in Clean or Unoxidized FeCrAl Alloys: A Review

“…The FeCrAl alloys have excellent resistance to aqueous corrosion, [15,[37][38][39][40] superior resistance to oxidation in high temperature air [17,20,41] and steam, [10,40,[42][43][44][45] and better creep/mechanical properties expected at high temperatures. [10,46,47] The superior high-temperature oxidation resistance of FeCrAl reduces the generation of hydrogen and associated exothermic heat of reaction with coolant during severe accidents, [45,48,49] while the creep/mechanical properties enhance the cladding burst margin. [46,47] FeCrAl alloys (and especially APMT) have an outstanding environmental resistance under the normal LWR coolant conditions, in addition to their excellent oxidation resistance under potential severe accident conditions.…”

Dynamic Probabilistic Risk Assessment Based Response Surface Approach for FLEX and Accident Tolerant Fuels for Medium Break LOCA Spectrum

“…Several studies [8,11,16,26] on the different chromium coatings ranges vary from 20 µm to 50 µm. In this paper, we selected 20 µm as the small coating thickness.…”

“…For example, Multilayered silicon carbide has a high melting point of 2700 • C but can fail from brittle fractures due to the differential pressure loadings and thermal stress [5]. These days, the ATF candidates that are being explored include silicon carbide (SiC) clads [5,6], chromium-coated zircaloy (Cr-coated Zr) [7,8], iron-clad (FeCrAl) [9,10], metallic fuel and uranium silicide (U 3 Si 2 ) [11]. In this paper, we investigated the three types of near-term ATF options within the DOE advanced fuels campaigns (AFC) directive for each class of silica, alumina, and chromium; multilayered SiC, iron-clad (FeCrAl), and Cr-coated Zr.…”