Good morning everybody.
In today's lecture we will continue discussions
on many more siting considerations which we
have no doubt brought out but in a little
more depth.
We mentioned that one of the important things
could be flooding.
How?
As I mentioned we take water for condenser
cooling from a river or from the sea.
It is quite likely that you could have high
waves in the sea or in a very large amount
of rain in the river areas you could have
a flood.
So it is very important that we assess any
site for a nuclear power plant from its flooding
potential.
So before you start designing the plant you
setup your design basis flood that means any
system which is required for operation should
be above that.
That is that minimum level above which any
structure of a nuclear power plant should
be there.
And this goes through lot of discussions.
Then besides this, it also could include tsunamis.
Then as I said snow melt, many times what
you call the sea level rises because of snow
melting.
Then suppose let us say there was a dam which
is located well away from the plant.
Not well away means not very far but should
that dam fail and the water come to the river
and that could be flooding.
Of course, there could be internal flooding
also but there is a part of the design internal
design of the plant.
This is an external event flooding when we
consider.
Now how do we go about this assessment?
We do it in two stages.
First stage what has happened before as a
part of history.
All the historical data on the cyclones, tornado
which have happened in that region we collect.
Then we also have the data on the wind speed
and all your temperatures; both the dry bulb
and the wet bulb temperature, how much has
there been any flash floods of a thing in
this last 50 years, we collect.
Then we subject these data into what is called
as an extreme value analysis wherein it looks
at the probability of the occurrence and its
magnitude both and then finally it tells how
what sort of a value we need to consider for
the design basis.
Normally once this data is analyzed to analyze
that we use a model which considers or this
meteorological and hydrological parameters
and we do this analysis.
And you might wonder how do we assure that
these models are okay.
There are institutions in the country like
the Central Water Power Research Station which
is located at Khadakwasla, near Pune wherein
they do model stories.
They really have a scaled model, scaled down
model and they really look at the moment of
the river, whether river changes course as
a function of time, all sorts of things, different
soil conditions everything is done.
So we do give a contract to these agencies
to do the analysis.
Then as I mentioned the failure of any barrage
or dam upstream and should there be a blockage
of the river because of landslide very very
close hilly area, anything can happen.
So all these nice things should be assessed.
So this model which ever developed will give
us an idea about what is the required design
basis flood level.
Now let us look at this tsunami.
What is tsunami?
It's the Japanese word.
It's a series of waves created when a body
of water is rapidly displaced.
That is is a huge amount of water is displaced.
That's why we had the tsunami in 2004, large
amount of water came onto the land.
So how does it happen?
It can be because of movement of the Earth
below the sea level.
When that happens that just in the land when
the earthquake happens it breaks the land
and pushes the material out, the plates which
break.
Here it is the water which is there which
comes out.
So all of us know that the tsunami can be
very devastating.
Here if you really look the way we'll be traveling
with the speed of hundreds of kilometers per
hour and when it comes to the shore where
it is stopped, the whole kinetic energy converts
the potential energy.
It just goes to a right as it happened in
the Fukushima in Japan in 2011.
The height of the waves went as much as 15
meters whereas still that time only they had
had tsunamis of 8 meters.
So in Kalpakkam also we had a tsunami of something
like 5 to 6 meters.
Of course, incidentally I was a witness to
the tsunami in 2004 and by a few seconds I
escaped.
And it can really cause lot of damage to property.
Now look at this figure.
How a tsunami happens?
Just as we call a fault in the Earth play
similarly fault on the base seabed also is
possible and let us say this earthquake occurs
so this plate moves because there is a crack.
This when this pushes this mass comes out
and this pushes water on the sea surface.
When this pushes the water and then tsunami
is generated now now.
Now these waves start moving outward and this
will be very low where you have a deep ocean
but when you come very close to the land where
the depth will be very less you are more or
less seeing that your land mass is trying
to stop this.
It is not allowing further.
So it rises in height and then grows.
That is where we get a large amount of force
and the large amount of force.
Then once this water has been pushed up, it
spreads out and of course the velocity of
the wave decreases and the velocity of the
wave decreases, the height increases, and
this is actually as a tsunami and just like
earthquakes here also there will be a wave.
Then it will come back.
Then it will be going back and forth.
That is sometimes referred to as seiche.
It is a French word for to sway back and forth.
Of course, this back and forth movement can
be even in lakes or rivers when you have the
seismic waves.
So looking at this we look at a site and all
these flood hazard if we feel that these things
can cause, require a very large design basis
flood level then we may have to think because
it's an economics.
You can't build all your plant in a very large
height.
So we have to look at that.
Then shoreline and riverbank erosion.
See suppose I have put up my plant very close
to a coast and you know the shoreline is never
constant.
It moves in areas where you have you will
find that somewhere the Earth sea is coming
in inside, somewhere you may find that the
beach portion is growing.
This is dependent on the wind directions.
This is dependent upon the sand deposition
patterns and different things.
So this can be observed in the based on the
historical observations on the shoreline.
So no erosion no – there is a wind it will
take the sand and anyway sea water erodes.
It's a very common things, and it erode it
some place it will deposit in another place.
In fact I have seen at Kalpakkam where I lived
for 40 years we found that after the construction
of some structures very close to in the beach
we found that the shoreline had changed.
Then we realized that after some years in
another place nearby villages somewhere the
sea has entered practically inside.
That is it has come in.
So somewhere protected somewhere.
So it has got a natural way of relocating
and redeposition.
So this needs to be considered before you
choose.
You should not put your plant in – the distance
should be good enough so that you are not
going to cost at least in the time of the
life of the plant.
Now there could be seasonal variations.
Sometimes it is called as the they are short-term
variations because of the different seasons.
So there could be a shore instability which
can happen and in case of river banks it can
even change the course of the river and it
can take another route.
So we have to be careful that this doesn't
happen.
And one more thing which we must consider
or keep in mind see many times from the nuclear
power plant or the thermal power plant, the
water used is let out into the river.
The point at which we reach out if it is very
low in case of some rivers getting flooded
the water might even not the river it may
enter through some of the pipes or some of
the what we call passages which we are given
to for the pipes to go into the river.
In fact this happened in the case of the Kakrapar
plant in Gujarat where excessive rain and
the water increase and the flooding was the
plant was flooded because of the spaces gaps
in the pipes and the wall which was sending
the water back to the river.
So this is an important point which needs
to be kept in mind.
Of course this river course changing is called
as meandering.
It's a technical term for meandering.
So we need to assess this site for all that.
Then aircraft location.
Now when does aircraft crashed generally take
place mostly during takeoff or landing.
That is the thing.
When it is in the air normally very rarely
turbulence happens but nothing -- crashes
have not happened because of turbulence per
se.
So first is it should not be in the vicinity
of a what you call, airport so that you can
have a crash on the NPP but mind you in spite
of all this we still consider in the design
of the containment that a plane of course
a military plane with a maximum energy can
hit and still the containment will not fail.
The containment structure concrete structure
will not fail.
Nevertheless, we still do this because we
are reducing one event so that's what why
we consider this distant from the airfield.
Now this as I said if it is a military airport
we need to be still far away.
Chemical explosions.
Now I mentioned to you about chemical explosion
maybe in a factory which is close to the plant.
So we must but not only that that could be
a road or a highway which is by the side of
your plant or very close to your plant and
let us say there is a explosion of the tanker.
Then your chemicals effects will be felt at
the plant.
So it is very important that not only a chemical
factory explosion any movement of chemicals
around this thing or let us say you take a
gas carrying, cooking gas, liquefied petroleum
gas.
There are tankers.
There are sometimes tankers carrying very
hazardous material.
So in case that happens whether your site
is okay.
Here I would like to give a small example
with reference to our prototype fast breeder
reactor which is under construction at Kalpakkam.
Here we found that the East Coast road was
going was about 3.5 kilometers from the site.
So immediately we decided okay if this is
3.5 kilometers what will be the effect.
We considered worst-case scenarios and then
satisfied ourselves that okay, our my [Indiscernible]
[00:17:08] plant is taken care.
There is no effect on the plant because of
such explosions.
Mind you all these details and studies we
need to submit it to the regulatory authorities.
Of course, then the Ministry of Environment
and Forests everything so that we get the
environmental clearance.
Environmental clearance is very very important
today for practically all industries.
We are not following that but luckily for
us in the nuclear industry everything is streamlined.
Now what or the other type of events which
we think can have effect on the nuclear power
plant.
Mining.
Suppose some mines are there nearby or some
drilling operations are going on.
Then that drilling can have effect on the
plant because continuous vibrations may be
transmitted to the plant and this can affect.
So we would not like any mines to be nearby.
One more thing sometimes in the mines you
ought to have explosives to open up and that
will cause a vibration to the NPP, Nuclear
Power Plant.
So one is I should be able to design for that
vibration or if I find feel that that going
to be higher value I would like to see that
I don't locate my plant.
I locate it a bit far away such that it cannot.
And these for these again you do lot of studies
by really blasting at some places and then
noticing how the vibrations are traveling
through the land in different places.
Then another thing let us say that there was
a warehouse which is storing some flammable
material or some toxic material.
There may not be factory.
It may be a warehouse where it is located
and then it may be they may be taking it and
transporting it.
So that should also not jeopardize.
Here again I remember I want to tell you we
take care that this should not affect.
So we make an assessment.
If it is okay.
We don't we don't say that okay if it is there
I will not.
So these are all under the desirable categories.
Then last but not the least we should see
that cooling water for the plant is always
available.
You must have a reservoir normally you would
find a large reservoir is built very close
to your nuclear power plant so that in the
worst case when pumping fails you are able
to give water to the plant to maintain the
shutdown cooling and keep the plant in a safe
condition even when power is not available.
So this is a very important matter.
In some cases we need to see let us take that
we have a sea water being used as a coolant.
Any ship or any shipwreck happening very close
to that weather it can affect the cooling
water.
All these aspects we need to be look into
and see that so we will say no ships should
come in that direction like that we put some
rules.
Now till now we saw what was happening to
the plant from the external.
Now we will look up what the plant will happen
to the site and public and environment because
of the plant.
What are the effects they can be?
Two, one is normally what we call conventional
pollution or there is radiological pollution.
And our main objective right from beginning
is to ensure that the radiological pollution
or radiological impact beyond the exclusion
boundary is within the prescribed limit not
only during normal operation even during abnormal
operation and what is the exclusion zone boundary
it is 1.5 kilometers, radius that circle you
draw within that okay outside that we should
not have that any radioactivity even under
normal or during abnormal conditions.
This is a very important thing because there
is a basic thing for which we are working.
Now second category of events is related to
the thermal and chemical pollution.
In the chemical pollution let us say we are
having power plant which has a reprocessing
facility and then also in the plant we have
chemicals for water treatment and all and
after we do the treatment the water we will
release it to the sea or river.
We should see that this release of chemicals
is controlled so that it does not result in
the death of the marine organisms including
fishes so that our environment on the sea
is not affected.
So this is very important.
So we have limits on what sort of concentrations
we should send.
So we normally we should dilute and be able
to send.
Then thermal.
Thermal is nothing but what I mentioned to
you earlier.
We take cooling water for cooling the condenser
in thermal power plant or a nuclear power
plant.
The water it enters at about a room temperature
of about 34-35 degree centigrade or about
30 to 32 degree centigrade and will come out
after removing the heat in the condenser and
if it comes at a very large temperature difference
again the marine organisms life would be disturbed.
They require a very minimum variation of temperature.
So this limit has been set by the Ministry
of Environment and Forests.
We have a criterion that it should not be
more than 7 to 10 degree centigrade.
Generally 7 in other cases 10.
Now this if that much is not possible we should
not – now let us look at, let us look in
a design where the temperatures are bit higher.
So what we need to do anyway we have to have
a higher flow of cooling water.
Higher water flow means higher pumping and
lot of cost.
So in some of the plants basically which are
cooled by river they take the water which
is coming from the condenser through open
ponds so that by the time it reaches the river
it cools off.
They are ways – see everything can be engineered.
Here is one thing which can be engineered.
Idea is the temperature should be within 7
degree centigrade which is a quiescent condition
for the marine organisms.
Here I would like to give you a small flavor
of one thing which happened about 20-25 years
back.
It was near the Ennore thermal power plant
which was earlier.
Now that Ennore thermal power plant doesn't
exist and there was a marine research center
by the side of the Ennore thermal power plant
somewhere little bit away.
They were trying to do research on what conditions
this marine organisms can grow.
How it is fishers and things like that and
once when there were failure in the condenser
tubes of the Ennore thermal power plant people
were called and this marine scientists also
they also went and when the condenser was
opened up they found lot of growth of this
marine organisms inside the condenser and
they saw the fish movement around the water
where the water is taken and let off in the
nearby sea.
It was really enormous.
So they concluded that our condenser conditions
are the most suitable because it is a constant
temperature.
So that shows that only thing what the marine
organisms require is a constant temperature
not much variation in temperature and the
condensers prude of course because of the
growth of these organisms we had some tube
failures.
Going on to the radiological impact.
Why radiological impact will occur?
If radionuclides are released.
Now as we saw earlier during normal times
we do release very controlled levels basically
in the gaseous form after going through filters,
and if you whatever anything we send out it
has got how it reaches the human.
So these are called as pathways.
So basically pathways are routes through which
people are getting exposed to the radiation.
How?
This can be through inhalation means breathing.
You are in an area where radioactive contamination
is there you inhale.
Then ingest.
Ingest means something could go through into
your system of food, food contaminated food
you take it could go.
If you recall after the Fukushima disaster
there is lot of worry asking people not to
eat the food, asking people not to eat the
fish because they were contaminated.
So that could be another route.
Of course, as I told you earlier forget about
radiological impact, radiological this thing
normally itself we are taking lot of potassium-40
with our food radioactive potassium-40 is
coming in.
So these are all only additional things.
Then immersion.
It could be a direct exposure to of a person
to the radioactive material.
This mostly can happen only to the workers,
occupational workers or in some establishments
which are handling you know sources of radioactivity
like X-ray units or irradiation plants like
that.
So this sketch shows how it can move.
This is a source.
So it comes out in the air.
This air can affect the vegetation and vegetation
eaten by cows.
So milk can get or the – it can goats also
can get.
Then that can slowly get to the man ingestion.
This is actually ingestion or it can come
through the soil.
It can radioactive thing deposit of the soil.
That can also go to the vegetation and that
also can have an external dose to the man
and then of course direct inhalation or immersion
whatever, both are possible.
So here these are the routes.
That is why when I mentioned to you that we
do take a environment survey means we do all
that.
We look at the food.
We look at the what you call milk.
We look at the vegetables everything we monitor
from time to time.
So what is the objective of this radiation
impact assessment is what is the individual
radiation dose coming to the population from
a nuclear power plant.
So we need to know the site characteristics.
That means we said the wind, the flood everything.
The wind comes into picture because let us
say some radioactive gases are released which
direction the plume will take, which direction
it will go, which direction will be more in
the winter, which they are actually more in
the summer all sorts of data we get.
Then the population distribution around the
place, which population more, which is less.
We get an idea.
Suppose I know the direction in this direction
I know that means this population is going
to be affected.
I can do some proper emergency evacuation
measures.
I might plan for that condition.
Then the food we eat, for example the dietary
habits.
For example when we take Kalpakkam we found
that rice is one of the items which is maximum
consumed by the public.
Maybe if I go to North it might be wheat.
So we find out what are the dietary habits
and then assess how which are the things.
So all this thing we do of course well before
the plant is built.
Then the we've identified which nuclide is
critical which can easily get to the common
man and look at that nuclide with more interest.
Let us look.
We just see this is a plume.
Now it will diffuse as distance is there.
Suppose you have a rain it might wash out
and deposit.
Suppose it is not there it may just the plume
may go.
There maybe eddies everything.
Then all these things require a modeling of
this taking the weather conditions into account
we need to assess how these things go to assess
the impact and here we have a continuous weather
monitoring station not only at Kalpakkam but
at different places along the coast nearby
Kalpakkam in a distance of about 20 to 30
kilometers.
We have continuous monitoring and continuous
data being through wireless transmission being
collected at Kalpakkam.
In fact many times and we get inputs from
the ISRO satellites about the weather conditions,
about ensuing weather condition like a cyclone
or a storm.
So all these data we build it into our assessment
of the radiation impact.
So first what is the source strength, how
much is the source, how many becquerels of
activity it has got, and then at what height
it is being put out.
You always see a chimney of course no smoke
comes out near a nuclear power plant but that
chimney height is decided such that the plume
which is generated by the time it reaches
the ground it would have dispersed a lot so
the effective per unit volume activity would
have come down a lot.
So the stack height is decided that way.
Then what sort of nuclide you are going to
release Odin, Krypton, Xenon what sort of
things you are going to release and what is
the duration of your release and how they
will change with the atmospheric condition.
So all this data as I mentioned the wind speed,
the air temperature, the humidity and all
parameters we get current and the past and
we are able to decide when I should release
the valve.
So even this is also possible.
Then let us take the other route of water
route.
Source where we are using and let us say we
are in a waste treatment plant so we have
lot of water which is having activity or let
us say there could be a surface or a subsurface
which has got this activated water.
In the case of your Fukushima we had to discharge
active water.
So that can go to sediments.
It can go to the plants both the terrestrial
and the aquatic plants and again the aquatic
animals officious they will take.
Then finally the dose will come to the man
from both sides.
So how the groundwater dispersion is very
important so that's why wherever we have this
waste treatment and waste immobilization plants
we continuously monitor the ground around
the area we look for activity and again these
are we decide our siting based on the soil
conditions, the ground water movement, etcetera.
but still nevertheless we continuously monitor.
So we want to ensure that the radionuclides
will not be transported very fast.
Now low-level radioactive waste as I mentioned
we store it in trenches or within the plant
area.
So there is always this is a source for through
subsurface water and suppose there is trenches
there is a leak.
It is possible.
So we use normally reinforced concrete cement
concrete trenches.
Then sometimes rainfall and seepage through
the trenches can happen because of the permeability
of the rock and soil in that area.
So that also can lead to dispersion.
So we really understand all these pathways.
We do lot of studies by examining the dispersion
by simulation with some other sources when
the plant has not been built and then later
we find out, use these models to validate
experimental model to validate our theoretical
model and then use it for the analysis.
Then population distribution.
It's a very important input as I mentioned.
Suppose on the day when I had my leak or when
I want to release something to the atmosphere
I must know in which direction the wind is
which population.
If the population is going to be very large
in that area then I would like to think twice
and this population distribution analysis
helps you even during emergency preparedness.
You know that okay today this emergency has
happened in this direction okay how many people
are there.
I need to evacuate about 1 lakh people.
So how many buses I require all this goes
into the emergency planning.
Of course, when we come to emergency preparedness
we will see how these are done.
So the population distribution we saw is very
important for us to know which population
– how much population is getting that dose
so that the average dose should not cross
any of the allowable limits.
Then let us look at the environmental impact
study.
Of course environmental impact study as I
mentioned is conducted by an independent agency.
We do consider the cooling water, the condenser
cooling water requirements and things like
that.
We do consider but the study what we do study
will not be acceptable.
It should be done by an independent agency.
That independent agency consultants they have
data of so many plants, thermal power plants
and all.
So they do have an idea how to go about it
and they also would give us solutions to the
different types of problems.
So we use their expertise.
So as I mentioned this cooling, the intake
structure, intake structure means where we
take the cooling water from the river or sea
and the outfall is where we put the outfall.
Now the temperature difference needs to be
maintained and this is again indicated for
different areas which is the local, the state
or the central pollution control board has
put limit and for this studies have to be
need to be done to say that this is appropriate.
This will not happen.
We do a lot of experimental modeling also
for this.
In summary I would say what we have looked
at in the last lecture and this lecture we
see a huge amount of effort which goes into
the site selection.
So why?
I repeat we are conscious of the safety to
the person.
Industrial safety sure.
We are conscious of that.
In addition to that we are very much conscious
of the radiological impact which it can cause,
not that radiation per se is bad nevertheless,
we would like to see that the normal radiation
levels which are persisting we should not
add too much into that.
We want to that additional value we want to
limit as low as possible.
One can say take one viewpoint very I should
say drastic viewpoint this can cause radiation
so why we go for it.
Not correct.
Everywhere there is a risk.
So that we have to see that the risk is acceptable
and here when the operation of so many plants
has shown the risk is not high.
I can just tell you one very very important
thing which people normally get scared sir
radiation if it happens today okay I am okay
but it can genetically affect somebody.
There could be mutations and cancer some could
be some other and it could have different
problems for my future generations.
Yes that was what was thought in the 40s and
50s but now we have data on all the people
who were exposed to the Hiroshima, Nagasaki
bombings in Japan in 1945.
All their survivors and their children, their
grandchildren everybody now it is something
like about 55 plus 14, 69 years of data we
have and the most surprising thing is they
say if we take the cancers which have happened
in that sample population, maximum but not
sure you can attribute only two cancers could
be because of radiation not yes because it
could be there are so many other causes.
So what I can tell you there is there nothing
to fear radiation but nevertheless we should
take every effort to say that the impact is
minimal.
Too much of anything is bad even if it is
like drinking you know nectar too much of
anything is bad.
So you see that the amount of safety consciousness
in a nuclear power plant is unlike any other
industrial activity like a chemical plant
or anything.
There may be revelations.
Here we have a regulation.
We have a regulating authority and the regulating
authority its performance over the last 30-40
years has been so good that we have had practically
no events which have released large-scale
reactivity to the environment.
Now this environmental impact study is a very
important part before we make a decision on
the site and as I mentioned environmental
impact along with the all data and the then
only we get the environmental clearance from
the Ministry of Environment and Forest.
Then only we can think about constructing
the plant.
Thank you.
