Analysis of reverse flow restriction device to prevent fuel dryout during loss of coolant and instability accidents of boiling water reactors

Radaideh, Majdi Ibrahim Ahmad

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https://hdl.handle.net/2142/95259 Copy

Description

Title

Analysis of reverse flow restriction device to prevent fuel dryout during loss of coolant and instability accidents of boiling water reactors

Author(s)

Radaideh, Majdi Ibrahim Ahmad

Issue Date

2016-09-07

Director of Research (if dissertation) or Advisor (if thesis)

Kozlowski, Tomasz X

Committee Member(s)

Brooks, Caleb

Department of Study

Nuclear, Plasma, & Rad Engr

Discipline

Nuclear, Plasma, Radiolgc Engr

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

• TRAC/RELAP Advanced Computational Engine (TRACE/PARCS)
• Boiling Water Reactor (BWR) instability
• Loss of Coolant Accident (LOCA)

Abstract

This work introduces a new method to increase the safety of Boiling Water Reactors (BWRs) during the BWR instability and Loss of Coolant Accidents (LOCA). The method is based on a device called Reverse Flow Restriction Device (RFRD) and its purpose is to allow the flow in the forward direction, but prevent the flow in reverse direction which occurs in multiple accident scenarios. In this thesis, detailed TRACE/PARCS simulations have been used to investigate the effect of RFRD on the peak clad temperature during BWR instability and LOCA. The device is simulated in TRACE by using high friction coefficients for the reverse flow to ensure that only forward flow is allowed. The results demonstrate that by adding the RFRD device, flow reversal in fuel bundles could be substantially blocked and so the inlet flow reversal is thus prevented. The RFRD device also showed a modest impact on reducing the power oscillations. The use of RFRD device could prevent fuel dryout damage by preventing excessive high clad temperatures due to sustained dryout without timely rewetting. For LOCA, the device is capable of containing the coolant inside the core during the blowdown and when activating the emergency systems which keep the peak clad temperature at lower levels. Moreover, the RFRD achieved the reflood phase (when the saturation temperature of the clad is restored) earlier than without the RFRD. Sensitivity results demonstrated that for LOCA, high reverse flow friction coefficient is needed and hence the RFRD should be well-fitted to the lower tie plate to be able to sustain the high pressure caused by the large coolant flow during the blowdown phase of LOCA.

Graduation Semester

2016-12

Type of Resource

text

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http://hdl.handle.net/2142/95259

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© 2016 Majdi Ibrahim Ahmad Radaideh. All Rights Reserved

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