Hot Channel Analysis of a 333 MWth Civil Nuclear Marine Core using the COBRA-EN Code


In this study, hot channel analysis of a 333 MWth civil nuclear marine Pressurized Water Reactor (PWR) core operating in steady-state conditions has been performed to determine whether it satisfies thermal-hydraulic (TH) safety limits. For this purpose, we have used the code COBRA-EN with standard and the tightest achievable fuel dimensions (lower pitch-to-diameter ratio (P/D)) and typical PWR TH conditions. The reactor power distribution was computed using the WIMS and PANTHER reactor physics codes. The analysis shows that even in the hot channel at 118% overpower, the minimum departure from nucleate boiling ratio (MDNBR) and the fuel temperatures remain well within TH margins for both the standard and low P/D geometry cores. It is also necessary to prevent boiling in the coolant. In the COBRA-EN model, the coolant does not begin to boil unless the core-averaged linear power rating exceeds 27 kW/m for standard geometry, which is 155% higher than the design value. At steady state, due to the increased pressure drop, a low P/D lattice leads to a reduced coolant flow rate. In turn, this leads to a higher temperature rise across the core, which affects temperature limits and the MDNBR. Nevertheless, we find that it is possible to increase the power density by more than 45% while remaining within TH limits.

Meeting Name

International Topical Meeting on Nuclear Reactor Thermal Hydraulics 2015, NURETH-16 (2015: Aug. 30-Sep. 4, Chicago, IL)


Nuclear Engineering and Radiation Science

Keywords and Phrases

Codes (symbols); Coolants; Hydraulics; Nuclear reactors; Temperature; Channel analysis; Cobra-en; Departure from nucleate boiling ratios; Dnbr; Marine cores; Marine pressurized water reactor; Pitch-to-diameter ratios; Steady-state condition; Pressurized water reactors; Civil nuclear marine core 1; Cobra-en; Dnbr; Hot channel analysis

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Document Type

Article - Conference proceedings

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© 2015 American Nuclear Society (ANS), All rights reserved.

Publication Date

01 Aug 2015