seminar guide

8/6/2019 Seminar Guide

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A Project Report on

ELECTRO- KINETIC ROAD RAMP

Submitted to

COCHIN UNIVERSITY OF SCIENCE AND TECHNOLOGY

In partial fulfillment for the requirement of the award of the

degree of

Bachelor of Technology

In

MECHANICAL ENGINEERING.

Submitted by

HEMANT KUMAR REG No. 15080216

DEPARTMENT OF MECHANICAL ENGINEERING

COCHIN UNIVERSITY OF SCIENCE AND TECHNOLOGY


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DEPARTMENT OF MECHANICAL ENGINEERING

CERTIFICATE

This is to certify that the project report entitled ELECTRO- KINETIC ROAD RAMP is being submitted

by HEMANT KUMARbearing REG NO. 15080216 in partial fulfillment of the requirement for the award of

the degree of Bachelor of Technology in Mechanical Engineering ofCochin University of Science and

Technology for the academic year2007-2011.

HEAD OF DEPARTMENT PROJECT GUIDE PROJECT CO-ORDINATOR

Mr. P.A. Job Mr.Sujith P.K. Dr. Senthil Prakash M.N.

Dr.Mathew Cherian


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Chapter 1: Introduction................................................................. 7

1.1 Report Outline..................................................................... 8

Chapter 2: Basic Structure of a Nuclear Reactor........................ 9

Chapter 3: Types of Nuclear Reactors.......................................... 11

Chapter 4: Severe Accident Scenario

4.1 Definition.......................................................................... 13

4.2 Causes for core meltdown................................................. 13

4.3 Significant Severe Accident issues................................... 14

4.3.1 Ex-vessel Accident Progression...............................15

Chapter 5: Ex-vessel Cool ability Schemes

5.1 Introduction........................................................................ 16

5.2 Top Flooding...................................................................... 17

5.2.1 Summary.................................................................. 19

5.3 Bottom Flooding................................................................ 20

5.3.1 Summary.................................................................. 22

5.4 Design for future reactors................................................... 23

Chapter 6: Conclusion.................................................................... 24

References....................................................................................... 26

List of Figures

Fig no. Title Page no

Fig. 2.0 Schematic Drawing of the principal components of a nuclear 9

reactor together with radiation shield and containment


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Fig 3.0 Reactor Types used worldwide, January 2004 11

Fig 4.1 Severe Accident Progression and associated phenomena 14

Fig 5.1 POMECO experiments on cooling of a particle bed with 19

downcomers.

Fig 5.2 The Comet Concept 20

Fig 5.3 Comet-PC for Bottom Flooding through Porous Concrete 22

Fig 5.4 Concept of core melt retention and cooling in future reactors 23

Abstract

In a severe accident scenario in a Light Water Reactors (LWR), the core of the reactor may melt down and

destroy the inner reactor vessel. This molten core, known as Corium,

discharges down to the containment surface after in-vessel failure. Containment is the last physical barrier to

release of radioactive fission products into the environment, thus it is extremely important to maintain its

integrity. This report primarily discus the various schemes for cooling of the molten corium in the containment

and hence preventing the containment failure.


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Chapter 1

Introduction

Even after 225 years of amazing advances, still James Watts steam engine remains the most important

invention to humankind, the first instance of generated energy. Almost every activity in our economy is

dependent upon energy. Without the ability to generate vast amounts of inexpensive energy on demand, there

would be no high yield agriculture, no manufacturing, no widespread exchange of goods, and certainly no

consumer economy. It is not too much of a stretch to say that insuring an adequate supply of energy is a

responsibility of present governments almost as critical as that of national defense. Today with the emergence

of Great Indian and Great Chinese dreams the demand for energy has unprecedented rise. The time to look at

the sources of energy other than limited fossil fuels has arrived. Among all the options available at present

Nuclear Energy has showcased enough promise to be considered as the energy for future.

But nothing comes free and nuclear energy also has its disadvantages, fatal radiations being the mos

threatening. Three Mile and Chernobyl are the black chapters in history of human advance on the nuclear

frontier. The safety issues in the design of nuclear power plants to avoid the reoccurrence of such disasters are

of utmost importance. Severe Accident Scenario is the one in which core of the rector melt away because of

excessive heat generated and get into the environment after damaging the reactor. Various strategies to arrest

the molten core at different stages have been developed throughout these years. Cooling of ex vessel or the


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containment of the reactor is an important step in avoiding the failure. This report deal with the primarily deals

with the two most important schemes for ex-vessel cool ability with an overview of few other techniques.

1.1 Report Outline

Starting with the brief description of the importance of nuclear energy in present world in the introductory

chapter the report gives a brief introduction to basic structure of a nuclear reactor in chapter 2. Chapter 3

discusses the different types of nuclear reactors presently being used all over the world. In chapter 4 severe

accident scenario is being described. Various probable causes for the accidents are discussed. Subsequently

significant issues related to it are mentioned and a brief description of ex-vessel progression of accident is

given. Next chapter discusses in detail the two most important schemes namely Top Flooding of corium and

Bottom Flooding of the molten core. Finally chapter 6 concludes the discussion and gives few critical remarks

on the present techniques. A detailed list of all the references is provided in the last.

Chapter 2

Basic Structure of a Nuclear Reactor


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The structure of a nuclear reactor in most basic form is shown below in the fig.2.0.

The following are essential components/systems of a thermal nuclear fission reactor.

fig 2.0 Schematic Drawing of the principal components of a nuclear reactor together with radiation shield and

containment [1]

1. The fuel the fissile material (U-235), either as found in natural uranium or enriched.

In some cases plutonium is added. The fuel is produced in the form of metal or oxide

pellets.

2. Fuel cladding a metal shell in which the fuel pellets are contained. It protects the

fuel from corrosion and prevents fission products from escaping.

3. A moderator made of light elements, it slows down the fission neutrons to thermal

levels without unduly absorbing them (not used in fast breeder reactors).

4. A coolant to transport the heat generated from the core to the steam generator for

driving the turbine.

5. Control rods made of neutron absorbing material, these can be moved in or out of

the core to control the reaction and maintain it at a critical level or to stop the reaction

during shutdown.


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6. A pressure vessel to prevent radioactive material from escaping in case of excessive

internal pressure.

7. A containment structure or neutron shield (concrete or other material) to protect

operators and the public from radiation.

Chapter 3

Basic Types of Reactors

A number of reactor technologies have been developed. Fission reactors can be divided roughly into two

classes, depending on the energy of the neutrons that are used to sustain the fission chain reaction namely:

Thermal reactors use a neutron moderator to slow ormoderate the rate of production of fast neutrons by

fission. Thermal neutrons (slow neutrons) have a far higher probability of fissioning U-235, and a lower

probability of capture by U-238 than the faster neutrons that result from fission, this increases the probability of

fission and thus sustain the chain reaction.Most power reactors are of this type.

Fast reactors sustain the chain reaction without needing a neutron moderator. They require highly enriched fue

in order to reduce the amount of U-238 that would otherwise capture fast neutrons.


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fig 3.0 Reactor Types in use worldwide, January 2004, [2]

Thermal power reactors can again be divided into three types, depending on whether they use Light water or

Graphite or Heavy water as the moderator.

There are 2 types of Light water moderated reactors are in use these days, namely:

Pressurized water reactors (PWR): About 60% of the worlds commercial power reactors are Pressurized

Water Reactors (PWRs). These are reactors cooled and moderated by high pressure, liquid (even at extreme

temperatures) water. They are generally considered the safest and most reliable technology. The main

components of PWR are: A compact core in a pressure vessel capable of containing ordinary water at high

pressure, a driven primary heat exchanger circuit at high pressure, a secondary coolant circuit at lower pressure

with a steam generator and turbine/electric generator system and a containment structure.

Boiling water reactors (BWR): A BWR has many similarities to a PWR but there is only one circuit with

water at lower pressure so that it boils in the core at about 285C. The water in the top part of the core is in the

form of steam, which has a lower moderating effect. The steam passes directly to the turbines, which are thus

part of the reactor circuit. Also, the control rods enter from below.


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Chapter 4

Severe Accident Scenario

4.1 Definition:

A severe accident by definition involves melting of core and release of radioactivity. The phenomena

involved in core melt accidents are very complicated because the main characteristics of the accident scenario

are the interactions of the core melt with structures, and water, and release, transport and deposition of the

fission product carrying vapors and aerosols. The interactions of core melt may lead to (i) ablation of structures

(ii) steam explosions and (iii) concrete melting and gas generation.

4.2 Causes For Core Meltdown:

In pressurized water reactors, boiling water reactors, and breeder reactors, the core can melt as a result of a loss

of coolant accident (in which all emergency core cooling systems have failed). This can also happen if the

emergency system fails with the steam generator secondary dry-out. A rapid loss of water from the reactor

system naturally stops the chain reaction. Borated water is injected by the emergency systems and thus in the

large-break accidents, control rod insertion is not needed to stop the fission reaction. Smaller breaks do need the

control rods to fully insert because water stays in the core and the highly borated water from the emergency

systems is naturally delayed. However, radioactive decay of the fission products in the fuel ceramic will

continue to generate heat. This heat (7% decreasing exponentially to 3% of full power) can cause the reactor

core to melt within an hour after coolant flow is stopped [3].

Other sources of heat may be present in a nuclear reactor core. If the reactor vessel has been breached and air

enters the reactor, core material such as graphite or zirconium (used in fuel cladding) may burn, sharply heating

the core.

4.3 Significant Severe Accident Issues


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The melt progression during the severe accident results in interaction of the melt with the

reactor, plant structures and the coolant. We can broadly classify these interactions in terms ofin-vessel

accident progression, and ex-vessel accident progression. During this, release and transport of fission

products and/or combustible gases may occur.

The in-vessel melt progression will end when either the vessel failure takes place or the melt is cooled and thevessel failure is avoided.

Similarly the ex-vessel accident progression will end when either the melt is cooled and stabilized or the

containment failure occurs.

4.3.1 Ex-vessel accident progression

The-ex-vessel accident progression involves the interaction of the products of the in-vesse

accident progression, namely fission products, hydrogen and corium melt with the

contents of the containment. In particular, if a melt pool is formed on the concrete basement, then

criticality may be achieved again since the concrete generally contains much water.

Various fission products and some gases are produced because of these interactions.

The containment failure may occur due to direct attack of the melt or due to the high pressure generated by the

gases produced resulting in steam explosion. The failure of containment results in the direct mixing o

radioactive fission products in environment hence leading to disaster.


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Two time zones can be defined namely early and late for the failure of the

containment. This is basically based on the behavior of the radioactive aerosol source in

the containment, which diminishes, exponentially with time, due to its deposition on the

containment floor and surfaces, and its dissolution in water. It has been observed that

with steam in the containment atmosphere 99.9% of the aerosols in the containmentatmosphere are removed in 46 h. Thus, the time span of interest for the early failure of

containment is 46 h and for the late failure of containment more than 46 h [4]. It

should be obvious that the greater public hazard is posed by the early failure of the

containment.

Chapter 5

Ex-Vessel Cool ability Schemes

5.1 Introduction

The containment vessel of a nuclear power plant plays an important role since it is the last physical barrier that

can minimize accidental release of fission products into the environment. Therefore maintaining the

containment integrity is crucial to minimize the consequences of a severe accident. It has been known that the

containment integrity could be challenged under extreme thermal and mechanical loads potentially generated in

a severe accident. The various phenomena threatening to containment integrity are direct containment heating(DCH), Steam explosion, and Hydrogen combustion. All these result in extreme thermal and mechanical loads.

Various accident managements measurements are proposed to avoid severe accident scenario. Similarly some

techniques are devised to minimize the effects once severe accident has happened. These techniques can be

broadly classified in two parts namely arresting the corium flow and cool it in in-vessel, and if it fails then

spread the corium in containment and cooling is done by flooding it with water [5].


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Thus the basic steps in ex-vessel cooling methodology are-

1). Spreading the molten corium over as large as possible area as fast as possible.

2). Flooding the corium surface with coolant to take away the heat from it.

Spreading of the melt is a very important process because of its connection with the melt cooling process. It isincorporated in the design of a reactor which decides the spreading of the melt and hence determines the height

of the melt pool that will have to be cooled subsequently. A well spread melt will be of lower depth than an ill-

spread melt and, thus, easier to cool.

Melt cool ability is perhaps the most vexing issue impacting severe accident containment

performance in the long term. Melt cool ability is essential to prevent both the basement

melt-through and the continued containment pressurization, thereby, to stabilize and to

terminate the accident.Provision of deep (or shallow) water pools under the vessel may

not assure long term cool ability/quench ability of the melt discharged from the vessel

Interaction of the melt jet may lead to very small particles (in the event of a steam

explosion), which may be difficult to cool in the form of a debris bed of low porosity.

Incomplete fragmentation will lead to a melt layer on the concrete basement under a

particulate debris layer and a water layer.

The melt cool ability has been under intense research interest all over the world. Two

major schemes employed most commonly are:

i). Top flooding, and

ii). Bottom flooding.

These are individually discussed in detail in following sections.

5.2 Top Flooding

The basic scheme for melt cooling in ex-vessel is Top Flooding. After RPV failure the

molten corium discharges to the containment. To remove the heat from this corium after

its spreading, coolant water is flooded over it. Three modes of heat removal from the

melt pool have been identified. These are the (1) initial melt-water contact; (2) the

conduction through the crust; and (3) melt eruptions into water, when the heat

generated in the melt is greater than that removed by conduction through the crust.


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Top flooding is in itself not a very efficient way to remove heat, the reason being that water on combination

with corium reacts with the molten metals which are present and come from core, forms crust on the top surface

of melt. This layer is formed very fast and then it arrests the further direct heat transfer. It acts as an insulator

and doesnt allow the intimate melt-water contact and reduces the heat transfer. The only heat transfer taking

place is due to conduction through the melt pool to containment body. This increases the temperature of the

containment and poses serious threats to its integrity.

Cooling done by Top flooding can be substantially increased by the use ofdown comers,

which channel the coolant water from the top of the debris bed to its bottom. The POMECO (Porous

experiments at KTH showed an increase of the dry out heat flux from 50 to 600%, thus accelerating and

improving the coolability of the debris (6). During these experiments it was found that the effect is independent

of downcomer geometry but depends only on the cross sectional areas.

Sometimes due to crust formation the gases being produced as the consequence of concrete erosion by hot

corium keeps on accumulating and lift it up from the central part which makes it a porous surface structure and

allow a more efficient cooling of the upper few cm of the original melt, while the bulk and the lower part of the

melt solidified in a dense form that excludes water ingression and efficient cooling. In reactors top flooding

alone is unlikely to stop concrete erosion by corium melts of typical heights. A theoretical model for the top-

flooding and associated cooling processes was developed at Forschungszentrum Rossendorf, which includes

water progression over the surface of the melt, and the subsequent crust growth and heat transfer from theflooded melt during ongoing MCCI. Heat transfer to the overlying water layer is calculated based on empirical

correlations for a smooth surface, considering the different boiling modes from film boiling to convection

boiling. Convective processes in the two-component melt take into account the gas release from the bottom

concrete layer. In case of typical decay power in the melt, however, the long term concrete erosion would not

stop, as heat conduction through the upper thick crust is unable to remove the decay heat at a sufficiently low

temperature level, for which the concrete would be stable. The thermal calculations for the sidewall of the top

flooded melt indicate a stable anchoring of the surface crust with the concrete wall even in case of internal heat

generation [7].


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fig.5.1 POMECO experiments on cooling of a particle bed with downcomers.

5.2.1 Summary

Thus the top flooding of molten corium is not a very efficient method for cooling the melt debris in ex-vessel.

The formation of crust at the top of the surface prohibits the contact of the melt and water and hence reduces the

effective heat transfer. Introduction of downcomers helps a lot in increasing the heat transfer. These

downcomers act as the channel for the flow of water to down layers of melt bed and hence increases the heat

transfer.

5.3 Bottom Flooding

In this scheme unlike to the top flooding, water is introduced from the bottom of the melt debris. This has been

investigated in the COMET experiments [8] performed in Germany at the Forschungszentrun Karlsruhe (FZK)

In this scheme, molten corium material, after release from the RPV, spreads onto a layer of sacrificial concrete

material (core catcher) located in the containment cavity, erodes this layer and finally reaches a matrix of plastic

water injectors buried in this layer. Upon contact with the molten core material, the plastic plugs melt and water


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is injected into the molten corium. The driving water pressure is due to the location of the water reservoir above

the containment cavity.

In COMET experiments, the melt was found to quench, in a relatively short time, to porous, easily penetrable

debris, with continued access of water to the regions of the solidified debris. Recent investigations are

concentrating on the possibility of replacing the array of flow channels by a layer of porous concrete, throughwhich the coolant water could be supplied to the melt.

Four major series of Comet experiments are performed till date these are Comet T, Comet U, Comet H andComet-PC.

In the COMET-T experiments iron and oxide melt in different percentages (initial temperature about~1800 C)

were used as melt simulants. The decay heat was not simulated. Two possible melt configurations are

considered: (i) a stratified configuration with a layer of the lighter oxide melt located above the metallic melt,

(ii) a uniform configuration, in which metal is dispersed inside the oxide melt due to the strong agitation of the

melt by gas release from the sacrificial layer. The main conclusion that has been drawn from the transient

cooling of thermite melts is that the behavior of the pure oxide melts does not differ very much from that of the

stratified metal and oxide melts as far as the coolability is concerned. The average porosity obtained was 30%

for the metal portion and 50 % for the oxide portion [9].

The COMET-U experiments were performed at the ANL in USA and were aimed at investigating the

coolability of corium melts with a high content of UO2. The major constituents of the melt are 52 % UO 2, 16 %

ZrO2, 13 % SiO2, 4% CaO and 11% Cr. The composition of the oxide fraction corresponds to the situation that


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proceeds after the erosion of the sacrificial concrete layer. The decay heat was not simulated. In this series it

was confirmed that corium melts behaved in the same way as the thermite melts in the experiments at FZK.

The COMET-H experiments were large-scale tests performed with thermite melts ofup to 1300 Kg. A decay

heat of 450 W/m2 (surface power density) was simulated during the experiments. This value for the decay heat

represents the highest level of decay heat that has to be managed in the reactor. In some experiments, due to thepartial or total closure of several nozzles by solid debris, the low water flow rate through the cooling channels to

the lower side was insufficient to cool some portion of the melt pool.

As the COMET concept is under evolution for plant application, the possibility to replace the array of flow

channels by a layer of Porous Concrete (see fig 5.3 forComet-PC concept) through which the coolant water

could be supplied to the melt is under investigation. As the radial erosion of the sacrificial layer was higher than

expected, flooding started from the side instead from the bottom and therefore resulted in a typical top flooding

scenario. Due to the existing sideward bypass for the coolant water, cooling of the bottom melt was however

incomplete and parts of the melt continued downward propagation, resulting in an erosion of the porous water-

filled concrete layer.

fig 5.3: Comet-PC for Bottom Flooding through Porous Concrete

5.3.1 Summary

Thus in Bottom flooding after erosion of a sacrificial concrete layer, the melt is passively flooded from the

bottom by passive injection of coolant water. This water is forced up through the melt. This results in the

evaporation of the water and breaks up the melt and creates a porous structure of the melt and hence improved

heat transfer. This porous melt solidifies in one hour in general and then permanently flooded by water. Now

days the injection of water is proposed to be done from layers of porous water filled concrete instead of array of


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water channels. Experiments have shown that this technique is much more efficient and fast in comparison to

top flooding.

5.4 Design for future reactors

Few changes in design are suggested for future reactors for the mitigation of severe accidents. This formally has

two steps, first to temporarily retention of molten corium in a shallow crucible called core catcher then

passively flooding it with water.

The bottom and side of a core catcher are assembled from a large number of cast iron elements, covered with

sacrificial and optionally protective material it is located in a compartment lateral to the pit. The related spatial

and functional separation isolates the core catcher from the various loads during RPV failure.

Within the core catcher, due to the effective cooling of the melt from all sides a stable state will be reached

within hours and complete solidification of the melt is achieved after a few days. The core catcher can

optionally be supplied by the Containment Heat Removal System (CHRS). In this active mode of operation, the

water levels inside spreading compartment and reactor pit rise and the pools become sub cooled, so further

steaming is avoided. This results in a depressurization of the containment in the long-term. Temporary retention

in the pit also ensures the collection and relocation of the core inventory independent of the accident scenario

and hence makes it independent of the inherent uncertainties associated with in-vessel melt pool formation and

RPV failure.

fig. 5.4 Concept of core melt retention and cooling in future reactors. [10]

Chapter 6

Conclusions


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Containment integrity in case of severe accident scenario is the most important issue, as it is the last physical

barrier to release of radioactive fission products to environment. Severe accident scenario is basically the

melting of the core because of excessive heat generation. This molten core first damages the reactor pressure

vessel and then discharges down to containment. Its discharge depends on the location and geometry of RPV

failure. The molten corium needs to be cooled quickly to protect containment.

The cooling of melt in ex-vessel involves two stages, first the spreading and second cooling of the core melt

Spreading needs to be done at fast rate and to large surface area to have effective cooling. Presently sometimes

containment is provided with a pool of water beforehand in the hope that this will help in quick cooling of melt.

Although it has been found out that the height of melt layer is same as the height of the water pool but yet it has

not been resolved that whether it helps or not [11]. Various modifications have been carried out in design of

nuclear reactors to have good spreading of melt. A new concept of core-catcher for European Pressurized Water

Reactors (EPR) is suggested. In this ex-vessel is provided with a retention crucible and this after failure of a

plug spreads to a large surface area and is then flooded by coolant.

The two schemes which are utilized for the cooling of melt are Top Flooding and Bottom Flooding. In Top

flooding once the melt is spread over the containment water is filled in the containment over the melt. This

initially causes large heat transfer and cools down the melt but very soon a crust formation occurs and it arrests

the further heat transfer through direct contact. It has been found that if channels are provided for water to go to

the deeper layers of melt then it increases the heat flux by large amount.

Second technique and by far the most effective one is flooding of melt through bottom of the melt. This is very

much effective as water comes in contact with melt, evaporates and results in formations of lots of voids in the

melt. These pours helps in heat transfer and results in quick cooling down of melt. Recently instead of flooding

water through array of flow channels, a concept of porous concrete filled with water is suggested, presently

experiments are going on to check its effectiveness.

After reviewing the present techniques it seems that presently we are not utilizing both the schemes together

We can have both top and bottom flooding together to have much more effective heat removal, as top flooding

is good in removing heat from upper layers of melt debris and bottom flooding can be used to cool the inner and

lower layers.

Viscosity of melt seems to play a very important role in spreading part. If we can provide core-catchers with

some material of low viscosity beforehand then on mixing with core melt it will reduce the viscosity of melt and


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helps in quick spreading of the melt. We can even make the crucible material with upper layer of some material

which melts down when comes in contact with hot corium and mixes with it and has low viscosity thus

reducing the viscosity of the melt. Melt-concrete interactions results in addition of concrete material to melt

which increases its solidus temperature which is bad once melt is spread but before it has been spread if we can

add some thing which can increase the solidus temp of the melt then it will help us in smooth spreading as no

solidification will occur in flow dura

References

[1] Lamarsh, J.R, Introduction to nuclear engineering. 2nd ed., Addison-

Wesley, 1983, chap 4, pg # 118, fig 4.5.

[2] www.wikipedia.com : article on Nuclear Reactor.

[3] www.wikipedia.com : article on Nuclear Meltdown.

[4] N. Yamano, Y. Maruyama, T. Kudo, A. Hidaka, J. Sugimoto, Phenomenological

studies on melt-coolant interactions in the ALPHA program, Nuclear

Engineering and Design vol.155, pg # 369-389, 1995.

[5] B.R. Sehgal, Accomplishments and challenges of the severe accident

research, Nuclear Engineering and Design 210 (2001) pg # 7994

[6] B. De Boeck, Prevention and mitigation measures to ensure containment

integrity, Nuclear Engineering and Design vol 209, issue 1-3, pg # 147-154,

2001.

[7] Konovalikhin, M.J., Sehgal, B.R., Investigation of volumetrically heated

debris bed quenching, ICONE-9, Nice, France, April 812, 2001
http://www.library.iitb.ac.in/searchbook/jsp/bookdetails.jsp?accno=154749http://www.library.iitb.ac.in/searchbook/jsp/bookdetails.jsp?accno=154749http://www.library.iitb.ac.in/searchbook/jsp/bookdetails.jsp?accno=154749http://www.library.iitb.ac.in/searchbook/jsp/bookdetails.jsp?accno=154749http://www.wikipedia.com/http://www.wikipedia.com/http://www.library.iitb.ac.in/searchbook/jsp/bookdetails.jsp?accno=154749http://www.library.iitb.ac.in/searchbook/jsp/bookdetails.jsp?accno=154749http://www.wikipedia.com/http://www.wikipedia.com/


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[8] H. Alsmeyera, G. Albrechta, L. Meyera, W. Hafnerb, C. Journeauc, M. Fischerd,

S. Hellmand, M. Eddie, H.-J. Alleleinf, M. Burgerg, B.R. Sehgalh, M.K. Kochi,

Z. Alkanj, J.B. Petrovk, M. Gaune-Escardl, E. Altstadtm, G. Bandinin Ex-vessel

core melt stabilization research (ECOSTAR), Nuclear Engineering and Design

vol. 235, pg 271284, 2001

[9] H. Alsmeyer, M. Farmer, F. Ferderer, B. W. Spencer and W. Tromm, The

COMET Concept for Cooling of Ex-Vessel Corium Melts, CD-ROM Proc. of

ICQNE6. San Diego, California (1998).

[10] D.Paladino, S.A. Theerthan and B.R. Sehgal, DECOBI: Investigation of melt

cool ability with bottom coolant injection, Progress in Nuclear Energy, Vol. 40,

No. 2, pg #. 161-206, 2002

[11] Alsmeyer and Werle, Kernschmelzkhlung fr knftige DWR-Anlagen. In: KFK-

Nachrichten, 26, 3/94, pp. 170178.


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