atw - International Journal for Nuclear Power | 2.2024

Environment and Safety
47
They also compared the empirical results addressing
a hypothetical nuclear reactor accident, the Canadian
Nuclear Safety Commission (CNSC) used MAAP4-
CANDU to approximate release of radionuclides to the
atmosphere through the accident [37] . While there
may be some merit to the Figure below, significance
requires additional scrutiny, if indeed the case for
SMRs. The equilibrium core used for verification
consisted of four primary nuclides: Uranium-238 at a
concentration of 5.65%, Uranium-235 at 49.19%,
Plutonium-239 at 43.64%, and Plutonium-241 at 1.32%.
This core represents an equilibrium CANDU core. Their
study included over 40 radionuclides, in addition to
Cesium-137. The empirical approach yielded a total
Source Term of 6.97E+18 Bq, whereas the CNSC
published data indi cates a total Source Term (magnitude)
of 4.50E+18 Bq. The following graph illustrates
how radionuclides with an extremely minimal source
term are released when radioactive material is released
due to a nuclear accident.
non-nuclear risks that members of our society are
already exposed to [39] .
Accident Type Total number Fatality Rate
Motor Vehicle 33,070 3E-4
Falls 44,686 9E-5
Fires 3,790 4E-5
Drowning 13,000 3E-3
Firearms 40,000 3E-4
Air Travel 1,176 9E-6
Falling Objects 2,227 1E-5
Earthquakes 64,082 2E-5
Lightening 130 5E-5
Tornadoes 116 4E-7
Hurricanes 16 4E-7
Nuclear Reactor Accidents 3 5E-9
Tab. 2.
Average Risk of Fatality by Various Causes
Table 2 justifies the safety of nuclear power as it
provides the fatality rate and accidents have happened
in the past, and nuclear power has the lowest numbers.
Based on the data in Table 3, nuclear has the lowest
greenhouse gas emissions.
Fig. 2.
Source term for significant radionuclides based on MAAP4-CANDU case study.
The above graph indicates that SMRs are constructed
with safety measures to minimize the likelihood of
accidents and to confine any potential radionuclide
emissions.
2.3 Risk Mitigation
One design element of SMRs that can greatly lessen
the severity of an accident is their larger lateral
surface area-to-volume (A/V) ratio. Compared to large
light water reactors (LWRs), this larger A/V ratio
can increase the removal of radioactive particles
caused by natural phenomena after a nuclear accident.
Before a radioactive release from the reactor core could
happen, for instance, the cladding surrounding the
fuel would have to give way, the pressure vessel‘s
integrity would have to be compromised, and the
containment structure surrounding the reactor would
have to be breached. The creation of emergency
planning zones surrounding the reactor, from which
an evacuation is organized in advance, improves
safety [38] . The Table, which is based on E. E. Lewis‘s
book projects the risks that the public faces from
nuclear reactor accidents and compares them with
Energy Type Death Rate/Year Greenhouse
Gas Emission
Coal 24.6 820 tonnes
Oil 18.4 720 tonnes
Natural Gas 2.8 490 tonnes
Biomass 4.6 78-230 tonnes
Hydropower 1.3 34 tonnes
Wind 0.04 4 tonnes
Nuclear 0.03 3 tonnes
Solar 0.02 5 tonnes
Tab. 3.
Death rates and greenhouse gas emission
through different electrical plant [40]
In the pursuit of shifting global energy systems from
fossil fuels to low-carbon sources, a variety of energy
alternatives are at our disposal, including nuclear
power and renewable energy technologies like hydropower,
wind, and solar. Nuclear energy and renewable
energy sources generally produce very little carbon
dioxide per unit of energy produced; they also significantly
reduce local air pollution levels more effectively
than fossil fuels do. Moreover, the mortality rate
associated with nuclear power is exceptionally low
Vol. 69 (2024)