The document analyzes major nuclear accidents at Chernobyl, Three Mile Island, and Fukushima. It finds that flawed reactor designs, human errors, lack of safety precautions, and inadequate emergency response were key contributing factors. It recommends improving nuclear plant design safety features, establishing rigorous training programs, developing comprehensive emergency plans, and fostering a strong safety culture in the nuclear industry.

1. MECH30632 Nuclear Systems
Answer:
Title: The Safety of Nuclear Power Generation: An Assessment of Nuclear Accidents
Introduction
Chernobyl, Three Mile Island and Fukushima are the major nuclear reactor accidents in the
history of nuclear power generation. These accidents have made public opinion on nuclear
energy to be very negative. However, the fact is that nuclear energy remains far safer than
fossil fuels and nuclear power plants have a lower risk of accidents and death rates
compared to fossil fuels, as shown in Figure 1 below (Ritchie, 2020). This article analyzes
the root causes, lessons learnt and recommendations from investigation reports of the
aforementioned major nuclear reactor accidents.
Figure 1: Safest and cleanest energy sources (Ritchie, 2020)
Chernobyl Accident
The main cause of Chernobyl accident was flawed reactor design. The plant was using
RBMK reactors, which had a positive void coefficient. These reactors were running at a low
power level, became very unstable and exploded due to uncontrolled power surge (Kortov
& Ustyantsev, 2013). The control rods of the RBMK reactors were poorly designed. The
length of these rods was found to be 1.3 meters shorter than required. The inadequate
number of control rods in the reactor also caused the accident. The reactor was found to
have 8 control rods against the minimum number of 15 as required by the international
standards. The plant also did not have a containment structure to prevent radioactive
material from escaping into the environment.
Human error was also a major cause of Chernobyl accident. The operators of the plant
violated the standard operating procedures and regulations of the plant before a routine
shutdown by running it at very low power without putting in place adequate safety

2. precautions (Khan, et al., 2018). The operators did not communicate or coordinate with the
safety personnel about the test procedure they were about to carry out. The operators did
not have adequate knowledge or training on nuclear reactor engineering and physics. There
was also no safety culture in the company. The planned test was delayed for 11 hours with
no emergency protection. There was also no rigorous emergency preparedness plan to
facilitate speedy evacuation of workers and surrounding populations.
Three Mile Island Accident
Three Mile Island nuclear power plant accident was caused by failure of equipment and
incompetent plant operators who were not able to understand the condition of the reactor
at particular times through the event. Instrumentation in the control room was deficient
and therefore could not detect the malfunctioning of the reactors. The plant operators did
not have the knowledge and experience to diagnose the problem and respond to the
reactor’s unplanned automatic shutdown and they were not adequately trained on
emergency response.
Fukushima Accident
Fukushima accident was largely caused by human error. Japan’s nuclear power sector
regulator, Nuclear and Industrial Safety Agency (NISA), allowed Tokyo Electric Power
Company (TEPCO), the owner of Fukushima plant, to operate the plant without
implementing adequate measures to protect the plant against tsunamis and earthquakes
despite the area being known to be prone to these natural disasters (Horii, 2015). Both
NISA and TEPCO did not follow the required international standards and best practices
regarding safety of nuclear power plants. As a result, they were not able to predict the
probability of the plant being hit by a massive tsunami. This would have necessitated an
upgrade of the plant’s design to incorporate state-of-the-art safety precaution measures
against natural disasters such as earthquakes, tsunamis and flooding (Acton & Hibbs,
2012).
The onsite emergency response teams and plant operators were not adequately trained and
prepared on how to respond to and manage emergencies such as high pressures and water
levels in reactors and containment of radioactive materials released. There was also lack of
clarity on the roles and responsibilities of different personnel of the emergency response
team and other external emergency response enters.
Conclusion And Recommendations
Chernobyl, Three Mile Island and Fukushima nuclear accidents were caused by flawed
designs and human error. The lessons learnt from these accidents have shaped nuclear
plant design and safety across the world. These lessons have resulted to several
recommendations that if implemented will prevent similar accidents or minimize their

3. severity in the future.
First is to improve the design of nuclear power plant components especially the reactors.
The reactors should be capable of remaining stable even at low power supply and other
complex operating conditions. The plants must be designed with improved and efficient
automatic shut-down mechanisms and automated inspection equipment. The automated
systems will help to identify any abnormalities in the plant operations and notify relevant
plant personnel and agencies. Another important design factor is addition of containment
structures to prevent release of radioactive material into the atmosphere in case of a
nuclear accident. Where possible, it is recommended that nuclear power plants be built
away from coastlines, rivers and active seismic zones (Sharma, 2011).
There is need to establish training institutions accredited by the relevant government-
affiliated nuclear industry agencies to offer relevant training programs to nuclear plant
operators and supervisors. Examples of these are the Institute of Nuclear Power Operations
(INPO) and National Academy for Nuclear Training that were established and mandated to
promote excellence in plant operation, management and training. Every person employed in
the plants should be adequately trained on the operations of the plant, standards of
excellence, operating procedures, and response to extreme emergencies. Use of plant-
specific simulators can help to expose the operators to extreme emergency scenarios during
trainings (Harris, 2011).
The nuclear power plants should establish comprehensive disaster preparedness and
mitigation plans. These plans will specify the involved stakeholders, their clear roles and
responsibilities, chain of command or communication in case of an emergency and
evacuation procedures. During a nuclear disaster, the concerned personnel should report to
relevant agencies and the surrounding population immediately (Aitsi-Selmi & Murray,
2016); (Zablotska, 2016). This will speed up response during emergencies. Every nuclear
plant should also have a multi-level emergency response teams that are adequately staffed
and equipped with well spelt out operating guidelines. Most importantly is to ensure
effective and timely communication between onsite and office emergency response teams.
Another recommendation is to provide psychiatric and psychological support to the
affected communities (Feder, 2016).
Above all, there is need to establish a safety culture in the nuclear power industry. Nuclear
power regulators and plant owners should prioritize safety of workers, surrounding
populations and the environment at all costs. Regulators should ensure that developers of
these plants have put in place adequate measures to prevent or mitigate potential risks
before approving their development plans and issuing them with operating licenses.
References
Acton, J. & Hibbs, M., 2012. Why Fukushima Was Preventable. [Online]

4. Available at: https://carnegieendowment.org/2012/03/06/why-fukushima-was-
preventable-pub-47361
[Accessed 21 April 2022].
Aitsi-Selmi, A. & Murray, V., 2016. The Chernobyl Disaster and Beyond: Implications of the
Sendai Framework for Disaster Risk Reduction 2015–2030. PLoS Medicine, 13(4), pp. 1-10.
Harris, R., 2011. What Went Wrong In Fukushima: The Human Factor. [Online]
Available at: https://www.npr.org/2011/07/05/137611026/what-went-wrong-in-
fukushima-the-human-
factor#:~:text=What%20Went%20Wrong%20In%20Fukushima%3A%20The%20Human
%20Factor%20Japanese%20officials,have%20reduced%20the%20accident's%20severity.
[Accessed 21 April 2022].
Horii, H., 2015. Root causes of Fukushima Nuclear Power Station accident and lessons to be
learned, Tokyo: University of Tokyo.
Khan, A., Hasan, M. & Sarkar, M., 2018. Analysis of Possible Causes of Fukushima Disaster.
International Journal of Nuclear and Quantum Engineering, 12(2), pp. 53-58.
Kortov, V. & Ustyantsev, Y., 2013. Chernobyl accident: Causes, consequences and problems
of radiation measurements. Radiation Measures, 55(1), pp. 12-16.
Ritchie, H., 2020. What are the safest and cleanest sources of energy?. [Online]
Available at: https://ourworldindata.org/safest-sources-of-energy
[Accessed 21 April 2022].
Sharma, P., 2011. Chernobyl & Fukushima: Lessons to be Learnt. Indian Journal of Surgery,
73(3), pp. 173-174.
Zablotska, L., 2016. 30 years After the Chernobyl Nuclear Accident: Time for Reflection and
Re-evaluation of Current Disaster Preparedness Plans. Journal of Urban Health, 93(3), pp.
407-413.