Nuclear Energy: Disadvantages of Nuclear Energy

Earlier in the discussion about advantages and disadvantages of nuclear energy we saw how nuclear energy is beneficial, if used in the right manner and its scope utilised to the fullest.
However, there is a great deal of radiation danger associated with Nuclear energy. It is capable of causing genetic disorders, thus once exposed, can affect generations to come adversely. Another drawback is the storage of nuclear wastes, as it too can lead to disastrous effects if not disposed or stored in the right manner.

A well known nuclear disaster was the attack on Hiroshima and Nagasaki by the United States during World War II. An experiment, as described by some, was a grave event in the history of nuclear energy and its effects. It was the first of its kind. Another infamous event is the Chernobyl disaster. Although an accident, it made the world realize that controlling such a potentially great power is not entirely in our hands. The accident happened during a test in a nuclear power plant. The extent of damage was controlled as the plant was shut down immediately, and the residents relocated. Even now, the city is in ruins, a pale picture of its past.

The most recent nuclear mishap was the Fukushima Accident in Japan. It was caused by an earthquake-generated tsunami. The nuclear reactor was seismically robust, however could not sustain the effect of the gallons of sea water that went inside the reactor, thus leading to power failure which in turn led to overheating. This ultimately resulted in a hydrogen explosion and subsequent events led to the discharge of radioactive materials into the atmosphere.

Disadvantages of Nuclear Energy

1)  Radioactive minerals are unevenly distributed around the world and are found in limited quantities.
2)  Supply of high quality uranium, one of the raw material, will last only for few decades.
3)  Nuclear waste from nuclear power plant creates thermal(heat) pollution which may damage the environment.
4)  A large amount of nuclear waste is also created and disposal of this waste is a major problem.
5)  The danger of accidental discharge of radio activity also exists.
6)  Starting a nuclear plant requires huge capital investment and advanced technology.
7)  Nuclear plants are opposed on moral grounds, by many groups, because of their close linkage with development of nuclear weapons.
8)  There are number of restrictions on the export or import of nuclear technology,fuels etc.
9)  Nuclear power stations are always at the risk from terrorist attack.
10)  Aftermaths of Chernobyl cannot be forgotten easily.
11)  Safety issues associated with nuclear power are hard to be overlooked.
12)  Proliferation of nuclear technology increases the risk of nuclear war too.
13)  The waste produced remains 'active' over many years and disposing it safely is a an issue which needs to be addressed properly.
14)  Nuclear power is not a renewable source of energy. Uranium is a metal that is mined from the ground in much the same way as coal is mined. It is a scarce metal and the supply of uranium will one day run out making all the nuclear power plants obsolete.

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Nuclear Energy : Advantages of Nuclear Energy

What is nuclear energy?

Nuclear energy is a powerful source of energy, generated during a nuclear reaction, by change in the nucleus of an atom. The source of nuclear energy is the mass of the nucleus and energy generated during a nuclear reaction is due to conversion of mass into energy(Einstein's Theory)

There are two ways to obtain nuclear energy:
1) Nuclear fission  and  2)Nuclear fusion.
In a nuclear fission reaction, the nucleus of a heavy radioactive element like uranium, plutonium or thorium splits up into smaller nuclei, when bombarded by low energy neutrons. A huge amount of heat is generated in this process, which is used in nuclear power plants to generate electricity.
Nuclear fusion reaction involves the combination or fusion of two light elements to form a heavier element and release uncontrollable energy. Thus it cannot be used to generate electricity, unlike fission reaction. Did you know that the sun’s energy is generated by nuclear fusion reaction? The heat and light that we get from Sun, is all due to the continuous reactions going on inside it. We can now imagine how much energy would be released in the nuclear fusion reaction, that it is the source of sun’s energy.
Let’s cut out the technical part behind nuclear power and discuss advantages and disadvantages of nuclear energy, starting with advantages.

Advantages of Nuclear Energy

1)  As compared to other conventional energy sources, Nuclear power produces very less amount of pollution.
2) Very small amount of raw material is required to generate huge amount of nuclear energy. To put it into perspective, about 28gm of Uranium releases as much amount of energy as is generated by 100 metric tonnes of coal.
3) Since they are required in small quantities, atomic materials can be easily transported to far-off places even at a global scale. Thus transportation is easy unless you are considering security part of it.
4) If nuclear power stations are operated upto their full capacity they can produce cheap electricityand gain from other benefits of Nuclear energy.
5) The quantity of nuclear waste produced is also small.Cons of this advantage are discussed in Disadvantages of Nuclear Energy.
6) It is a very reliable source of energy. The average life span of a nuclear reactor is approx. 40 years which can be extended upto 60 years.
7) Nuclear power stations are usually very compact compared to thermal stations.
8) Although the initial capital cost of building a nuclear plant is high, the maintenance and running costs are relatively low.

Nuclear power has great prospects in the near future as nuclear power plants are efficient and do not produce any kind of pollution, unlike other sources. All in all, if nuclear energy is implemented extensively and its potential is exploited well, it would bring down the use of other important conventional sources of energy.

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Spiral Model : Advantages and Disadvantages

What is the Spiral Model?

The Spiral Life Cycle Model is a type of iterative software development model which is generally implemented in high risk projects. It was first proposed by Boehm. In this system development method, we combine the features of both, waterfall model and prototype model. In Spiral model we can arrange all the activities in the form of a spiral.

Each loop in a spiral represents a development phase (and we can have any number of loops according to the project). Each loop has four sections or quadrants :
1. To determine the objectives, alternatives and constraints. We try to understand the product objectives, alternatives in design and constraints imposed because of cost, technology, schedule, etc.
2. Risk analysis and evaluation of alternatives. Here we try to find which other approaches can be implemented in order to fulfill the identified constraints. Operational and technical issues are addressed here. Risk mitigation is in focus in this phase. And evaluation of all these factors determines future action.
3. Execution of that phase of development. In this phase we develop the planned product. Testing is also done. In order to do development, waterfall or incremental approach can be implemented.
4. Planning the next phase. Here we review the progress and judge it considering all parameters. Issues which need to be resolved are identified in this phase and necessary steps are taken.

Subsequent loops of spiral model involve similar phases. Analysis and engineering efforts are applied in this model. Large, expensive or complicated projects use this type of life cycle. If at any point of time one feels the risk involved in the project is a lot more than anticipated, one can abort it. Reviews at different phases can be done by an in-house person or by an external client.

Why spiral model is called meta model?

Spiral model is also called as meta-model because in a way it comprises of other models of SDLC. Both waterfall and prototype models are used in it. Here we do software development systematically over the loops (adhering to waterfall approach) and at the same time we make a prototype and show it to user after completion of various phase (just in case of prototype model). This way we are able to reduce risks as well as follow systematic approach.

Now let’s discuss the advantages and disadvantages of Spiral Model in detail.

Spiral Model Diagram

Advantages of Spiral Model

1)  Spiral Life Cycle Model is one of the most flexible SDLC models in place. Development phases can be determined by the project manager, according to the complexity of the project.
2)  Project monitoring is very easy and effective. Each phase, as well as each loop, requires a review from concerned people. This makes the model more transparent.
3)  Risk management is one of the in-built features of the model, which makes it extra attractive compared to other models.
4)  Changes can be introduced later in the life cycle as well. And coping with these changes isn’t a very big headache for the project manager.
5)  Project estimates in terms of schedule, cost etc become more and more realistic as the project moves forward and loops in spiral get completed.
6)  It is suitable for high risk projects, where business needs may be unstable.
7)  A highly customized product can be developed using this.

Disadvantages of Spiral Model

1)  Cost involved in this model is usually high.
2)  It is a complicated approach especially for projects with a clear SRS.
3)  Skills required, to evaluate and review project from time to time, need expertise.
4)  Rules and protocols should be followed properly to effectively implement this model. Doing so, through-out the span of project is tough.
5)  Due to various customizations allowed from the client, using the same prototype in other projects, in future, is difficult.
6)  It is not suitable for low risk projects.
7)  Meeting budgetary and scheduling requirements is tough if this development process is followed.
8)  Amount of documentation required in intermediate stages makes management of project very complex affair.

I hope after reading the benefits(pros)and drawbacks(cons) of Spiral model, you will be a better judge to which model suits your requirements best.

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Update : Recently a new friend of mine, Anja Skrba, translated this article for her Croation readers. We appreciate her hard work. You can check her article by clicking here(opens in new window).

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Earned Value Management : Advantages and Disadvantages

Earlier we saw what Earned Value Management is, and calculations in Earned Value Analysis. In project management, we use the concept of earned value to measure and predict the progress in the on-going project. It has become very popular now a days as a perfomance measuring method. Lets discuss the advantages and disadvantages of project Earned Value Analysis (EVA) / Management (EVM).

Earned Value Management Advantages and Benefits

1) EVM keeps the management on their toes. As EVA is done periodically, management tries to make sure that all the project parameters are on track.
2) It is probably the only system used at present which tracks the project in terms of work, time and money.
3) Timely performance measurement makes sure that steps can be taken to the bring project back on track before its too late.

Earned Value Management disadvantages and drawbacks

1) While doing earned value analysis, we don't take quality into consideration. It may be possible that our project is scoring high on earned value performance scale, but the quality of work is below par. Quality is an important criteria in any project, and unfortunately it is not considered in EVA.
2) In EVM, we take planned value as the baseline, using which we do our calculations and we make predictions. But there is always an element of uncertainity involved while doing any predictions. Our project may be on schedule when EVA is done, but because of unforeseenable risks it can get delayed at later stages. So basing our assumptions on Planned value is like playing with fire.
3) Cost of implementing Earned value management causes managers to not use it extensively. Generally, a software is required and coordination between different departments should be very good for it to achieve its goal.
4) Time required, to collect all the relevant data pertaining to Actual costs, is a lot in big and diverse projects.

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Earned Value Analysis terms and Formulae

Earned Value Analysis terms

Earned Value Management is one of the most common techniques used to measure the performance of the ongoing project. To implement earned value analysis in project management, it is important to first understand the following EVA terms and formulae.

Planned Value (PV):
Also called Budgeted Cost of Work Scheduled(BCWS), is the cost that is proposed to be utilised on an activity during a specific time frame.

Actual Cost (AC):
Also called Actual Cost of Work Performed(ACWP), is the aggregate cost that is spent on an activity while its execution, during a specific time frame.

Rate of Performance (RP):
It is the rate at which the project is progressing. Mathematically, it is the percentage of the work actually completed out of the total work that was scheduled to be completed till that point of time.

Earned Value (EV):
Also called Budgeted Cost of Work Performed(BCWP), is the estimate of the value of the work completed, on the basis of how much work should have been completed and how much work was actually completed.
EV = PV X RP

EVA Chart

Illustration to explain these terms:
Consider a project where the work has to be completed in two months in Rs 20,000. Cost breakdown is Rs.10,000 for each month. The work scheduled in each month is half of the total work to be completed.
By the end of the first month, the project has completed only 25% of the total work to be completed, but the cost utilised is that of 50% of the total work.

Also given that, for completion of 25% work, the actual cost(AC) incurred =50% of total budgeted cost
=10,000

Now from given data :-
The planned value(PV) for the work to be completed by the end of the first month
=50% of total
=50% of 20,000
=10,000

The rate of performance(RP)= Percentage of ratio of work actually completed to the work scheduled to be completed
=(25/50)X 100
=50%
This implies that only half of the work scheduled to be completed by the end of the first month has been completed.

Now, the earned value(EV) or the value of the work actually completed in monetary terms
=Rate of performance X Planned Value of work to be completed till the first month (EV = PV X RP)
=50% of 10,000
=5,000
This implies that we have utilised Rs.10,000(AC) for the work which should have utilised Rs. 5,000(EV) according to our budget.

Some more important terms in Earned Value Management:

Cost Variance (CV):
As the name suggests, Cost Variance calculates the deviation between the cost actually incurred and the planned cost. It checks whether we have gone according to our budgeted costs or not.
CV = EV - AC

Cost Performance Index(CPI):
Cost Performance is used to estimate the projected or actual cost of completing the project based on the performance to date.
CPI = EV / AC

Schedule Variance (SV):
Schedule Variance calculates the deviation between the actual and planned time taken to complete the project or an activity of a project. It checks whether the project has taken more or less time than that of the planned schedule.
SV = EV - PV

Schedule Performance Index(SPI):
Schedule Performance Index is used to estimated the projected time to complete the project.
SPI = EV / PV

Estimate At Completion(EAC):
Used to find the estimate cost of the project at completion, going by the present performance.
EAC = PV of whole project/CPI

Estimated time to complete:
Used to find the approximate time required to complete the project, going by the present performance.
=Original time/SPI

Illustration:
Take the above example to understand these terms.

Cost variance(CV)=EV - AC
=5,000-10,000
=-5,000

Cost performance index(CPI)=EV / AC
=5,000/10,000
=1/2

Schedule variance(SV)=EV - PV
=5,000-10,000
=-5,000

Schedule performance index(SPI)=EV / PV
=5,000/10,000
=1/2

Estimate At Completion(EAC)=PV of whole project/CPI
=20,000/(1/2)
=40,000
This indicates that the project which had to be completed in a budget of Rs.20,000 will be completed in Rs.40,000(if the rate of performance is the same).

Estimated time to complete:
=Original time/SPI
=2 months/(1/2)
=4 months
This indicates that the project which had to be completed in 2 months will be completed in 4 months, if the work goes on in the same way.

Earned Value Illustration

Negative values denote:
If CV is negative, it means that actual cost of performing the work is more than planned (AC > PV)
If SV is negative, it means that the activity took more time than planned to complete.

CPI interpretations:
=1: the actual cost = planned cost
<1: actual costs are more than the budget >1: actual costs are under budget

SPI interpretations:
=1: on schedule
<1: behind schedule >1: ahead of schedule

After going through the definition, need and terms related to earned value management, I hope you will be able to use this tool properly to rate the performance of your project. Will Earned Value Analysis work for your project?

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Autobiography of a Word Processor

Born in the year 1978, with tremendous efforts to create a unique word processor, I was yet another revolutionary product.
They initially created me for the purpose of easing out their essay writing skills. As my newer versions came into place, I had become a software that could even tell mistakes, correct grammar and help with coding. With each version, I was brought in with something new and was not limited to just the functionality of a typewriter with modifying options. Providing perfection at every step and easing out typing had become my sole function.
Slowly and steadily, by 1986, I became the largest selling application software. But that is when my position started being threatened by other similar copied softwares developed by other companies. Since people always go in for better and advanced products, the story is the same for my counterparts too. They developed, they used, they left us. Harsh, but true. So they left me for the better ones by 1995.
But soon, after the failure of others, I came into the limelight again by being used in the mobile revolution. And here I am, 30 years hence, continuing to win hearts of millions across the world.
Read Grievances of A Software (Just 4 Fun)

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Earned Value Analysis

What is earned value analysis?

Earned value analysis is an approach for measuring how much work has been completed in a project at given point of time and performance.
This analysis can be done by calculating how much time, the work has taken and the resources it has utilised. These values are then compared with the planned values of time and resources. If the time taken to do the particular task is greater than what was planned, it means that the project is running behind schedule. Similarly, if the resources utilized are more than what were planned, it means the project has not been managed efficiently in terms of resources.

Formally, Earned value analysis may be defined as a tool to objectively measure project performance by integrating scope, time and cost data. Earned value management also provides a means to forecast future performance based on past performance.

Earned Value Terminology

Earned Value Analysis (EVA) - It is a quantitative technique using which we can evaluate the performance of project and predict the final results, for this we compare present progress and cost incurred to planned estimations.It is the most comprehensive trend analysis technique.
Earned Value Management (EVM) – It is project management methodology used for monitoring and controlling our project by measuring the performance Work Breakdown Structure (WBS).
Earned Value Analysis terms and Formulae

Earned Value Analysis And Project Management

Earned Value Analysis is a Cost Control tool in Project Management.
It is used as a forecaster and tracker for measuring the progress of the project in terms of work done and resources utilized. It should be noted that both these terms (work done and resources utilized) are inter-related when it comes to execution of a project.

A baseline (original plan plus approved changes) can determine how well the project is meeting its goals and baseline acts as a benchmark.
Earned value technique compares the cumulative value of the budgeted cost of work performed(earned) at the original allocated budgeted amount to both, the budgeted cost of work scheduled(planned) and the actual cost of work performed(actual).

Actual information must be entered periodically to use Earned Value Analysis:

•  Was each item of the Work Breakdown Structure(WBS) completed or approximately how much of the work was completed,
•  Actual start and end dates of the activities/tasks,
• Actual costs of individual activities and tasks.

A "threshold" or tolerance point for the constraints in a project - time, cost and scope may be kept. Actual values should be kept below the tolerance levels. If the project constraints exceed these threshold values, it acts as a "danger sign" and required steps should be taken to address it immediately or at least some changes be made in the future plans to accommodate the discrepancies without much hassle.
Earned value analysis includes some easy mathematical formulae, based on common sense. So if you find these formulae too confusing, and think the only way to remember them is to mug them up, don't worry you will soon master them with the help of little understanding.....

Why is Earned Value Analysis done? Need of EVA in Project Management (PM)

Meeting project deadlines within a reasonable budget is hard to achieve. Focusing on both the parameters is a difficult but a necessary task. Without monitoring and controlling the project, it is nearly impossible to complete it within the scope, time and cost. Compromising on one of these three factors leads to the over utilization of other(s), which is not desirable and may lead to contractual penalties.
To complete a project in the given timeframe and within the given resources, it is necessary to plan for their judicious use, not only at the beginning of a project but also during its execution. This is essential to make the project adapt to external changes and absorb irregularities in the schedule.
This is where Earned Value Analysis comes into the picture. It is used as a tool for cost control as it is very helpful in determining how the project is going, in terms of cost, scope and time. That is, whether the cost is under control and if it will go over our planned budget or in how much time the project would be completed if we continue working at the same pace.
Thus Earned Value Analysis is helpful to plan and make changes in our plan depending on the current scenario and other internal and external factors which may influence the project later on.

Note that Earned Value Analysis calculations for any project can be done at any point of time, but if we are not using earned value management, we might not get accurate results.


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