Indo - UK: Premature, Oscillation-Induced Critical Heat Flux ("Premature OICHF")

Lead Research Organisation: Imperial College London
Department Name: Dept of Mechanical Engineering

Abstract

Water is an excellent coolant for nuclear reactors, but steam is a very poor one. The ability to predict with confidence, but without excessive conservatism, the point at which cooling by water will turn into cooling by just steam is absolutely vital. The the rate of transfer of heat at which this transition occurs is known as the "critical heat flux" (CHF).

Predicting the circumstances under which CHF would occur (and then making sure that reactor operating conditions stay well away from them) is a very large part of the thermal hydraulic design of water cooled reactors.

There are some, unusual, circumstances in which the flows inside a nuclear reactor can become unsteady and cyclical, with flow-rates rising and falling with time. Under the circumstances, predicting the critical heat flux not surprisingly becomes rather more complicated and difficult.

This project is attempting to build a computer model which will predict when critical heat flux occurs in the presence of cyclical flows. The second strand of this project is to conduct experiments in which a test section is exposed to a cyclical flow, and the occurrence or not of critical heat flux is observed. The model we develop will then be tested and refined against these measurements.

A validated, general-purpose tool for predicting critical heat flux under conditions of oscillatory flow will be a useful additional capability available to reactor designers and safety analysts.

Planned Impact

Nuclear power worldwide is a very important source of electricity, and it is a source upon which it looks probable that increased reliance will be placed in future, as concerns about the burning of fossil fuel and so on increase.

All nuclear plants need to be carefully designed to ensure that they remain properly cooled during both normal and under fault conditions. For a water-cooled plant, this means cooled by liquid water, as opposed to by steam. A better ability to predict the transition from water cooling to steam cooling will allow better design decisions to be made, and allow more reliable selection of setpoints, and thermal and power limits, and so on.

This will have significant economic benefits to the plant builder and operator, and ultimately to the consumer as it will prevent the costs of the plant being higher than they would otherwise be, and thus will similarly be reflected to it in electricity prices being less high than they might have been otherwise.

Publications

10 25 50
publication icon
Hänsch S (2016) The hydrodynamics of microlayer formation beneath vapour bubbles in International Journal of Heat and Mass Transfer

publication icon
Hänsch S (2017) Mechanistic studies of single bubble growth using interface-tracking methods in Nuclear Engineering and Design

publication icon
Giustini G (2018) Modelling of bubble departure in flow boiling using equilibrium thermodynamics in International Journal of Heat and Mass Transfer

publication icon
Giustini G (2019) Microlayer evaporation during steam bubble growth in International Journal of Thermal Sciences

publication icon
Hänsch S (2019) Microlayer formation and depletion beneath growing steam bubbles in International Journal of Multiphase Flow

publication icon
Walker S (2019) Phenomenological modelling of film-dryout 'critical heat flux' in Nuclear Engineering and Design

 
Description This is current work in progress. It is particularly timely, as recent critical heat flux events in Switzerland seem to be directly associated with the oscillatory behaviour being addressed here.
Exploitation Route This is current work in progress. It is particularly timely, as recent critical heat flux events in Switzerland seem to be directly associated with the oscillatory behaviour being addressed here.
Sectors Energy

 
Description Collaboration with Indian DAE BARC 
Organisation Bhabbha Atomic Research Centre
Country India 
Sector Public 
PI Contribution We are collaborating in a series of projects under the Indo-UK Civil Nuclear Programme
Collaborator Contribution We and BARC work together on developing measurements associated with various aspects of nuclear thermal hydraulics, and in the development and validation of models of these phenomena
Impact Multiple publications, multiple visits to BARC, multiple hostings of Indian scientists in the UK
Start Year 2015
 
Description Indo-UK Civil Nuclear Network Conference & Meeting. 30 - 31 October 2019 Halifax Hall, Sheffield University. 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Study participants or study members
Results and Impact Indo-UK Civil Nuclear Network Conference & Meeting. 30 - 31 October 2019 Halifax Hall, Sheffield University. Annual gathering of researchers working on collaborative Indo-UK civil nuclear research projects. Talks and presentations on work done under Indo-UK collaborative grants.
Year(s) Of Engagement Activity 2019
 
Description Indo-UK Civil Nuclear Network Meeting. 03 July 2017 Mechanical Engineering Department, Imperial College London. 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Study participants or study members
Results and Impact ndo-UK Civil Nuclear Network Meeting. 03 July 2017 Mechanical Engineering Department, Imperial College London. Annual gathering of researchers working on collaborative Indo-UK civil nuclear research projects. Talks and presentations on work done under Indo-UK collaborative grants.
Year(s) Of Engagement Activity 2017
 
Description Indo-UK Civil Nuclear Network Meeting. 19 - 20 December 2016 Halifax Hall, Sheffield University. 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Study participants or study members
Results and Impact Indo-UK Civil Nuclear Network Meeting 19 - 20 December 2016 Halifax Hall, Sheffield University. Annual gathering of researchers working on collaborative Indo-UK civil nuclear research projects. Talks and presentations on work done under Indo-UK collaborative grants.
Year(s) Of Engagement Activity 2016
 
Description Indo-UK Civil Nuclear Network Meeting. 20 September 2018 The Open University, Milton Keynes. 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Study participants or study members
Results and Impact Indo-UK Civil Nuclear Network Meeting. 20 September 2018 The Open University, Milton Keynes. Annual gathering of researchers working on collaborative Indo-UK civil nuclear research projects. Talks and presentations on work done under Indo-UK collaborative grants.
Year(s) Of Engagement Activity 2018
 
Description Invited Lecture on the boiling, DNB, and its prediction, at BARC, Mumbai, February 2020 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact An invited lecture on boiling, DNB, and its prediction, to scientists from the Indian DAE laboratory BARC, and the associated HBNI University Institute
Year(s) Of Engagement Activity 2020
 
Description Invited lecture to Westinghouse (Sweden) Meeting og BWR fuel users 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact I was invited to give a lecture on BWR fuel Critical Heat Flux prediction methods
Year(s) Of Engagement Activity 2017
 
Description Online resources: official website of the Indo-UK Civil Nuclear Network, https://indouk-civilnuclear.org 
Form Of Engagement Activity A magazine, newsletter or online publication
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact Generation of online resources available to everyone is interested at https://indouk-civilnuclear.org. Information on current and previous Indo-UK grants; publications; events; past and upcoming workshops and meetings.
Year(s) Of Engagement Activity 2018,2019,2020
URL https://indouk-civilnuclear.org