Hamon
Ultimate heat sink
cooling tower
Emergency
Cooling
Tower
2
Ultimate heat sink cooling towers: an additional piece of safety within
Application for Emergency Cooling Towers
The safe cooling of the nuclear island is a must because
this is the ultimate heat discharge in the process. In the
case of Fukushima an Emergency Cooling Tower in
combination with a safe water and energy supply would
have provided the necessary cooling and the required
water for it.
The International Atomic Energy Agency, IAEA, especially requests that the “unavailibility of the heat sink”
due to “external events” needs to be considered in the
design and that the adequate reaction time shall not be
less then 48 hours. (1)
In case of a shut down of the nuclear power plant the
nuclear core still requires a permanent cooling capacity
of approx. 50 MW.
This equals a water flow of 2150 m³/h with a cooling
range of 20 K or about 100000 m³ within 48 hours.
If the coolant from the river, lake or sea is blocked due
to an external event (like airplane crash, blocking of water
intake and pumps due to debris, dam brake, water
shortage, or other events), a huge reservoir of coolant
is needed to provide the cooling for the reactor.
An ultimate cooling system which includes a cooling
tower needs only about 3% of this water quantity
(3000 m³) to compensate the evaporation losses.
(1)
ar. 2.26 and 2.27 of IAEA Safety Standards Series, External Events
p
Excluding Earthquakes in the Design of Nuclear Power Plants, Safety
Guide No. NS-G-1.5, 2003
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This quantity can be stored within the confines of an
ultimate heat sink cooling tower. In the worst case the
fill up can be handled with trucks.
An ultimate heat sink cooling system consisting mainly
of cooling tower, pumps, piping and valves can be integrated in new and in already existing nuclear power plants
where the risk assessment shows the need for such a
cooling system.
Development of state of the art
Ultimate cooling is one of the critical safety systems in
a nuclear power plant and its characteristics are defined
considering the environment and the external risks to
be covered for each specific power plant. Therefore,
international standards or specifications do not thoroughly
describe the cooling towers that are adapted to local
a Nuclear Power Plant
circumstances and design philosophy. Consequently,
in Europe, well known nuclear power plant operators,
such as EDF, EnBW, and RWE have developed internal
specifications covering this subject.
HAMON, as a specialist has been closely involved in the
development of these specifications. In 1991, after 2 years
of studies and work, the EDF standard for emergency
cooling tower was completed and approved by the French
Safety Authorities. It covers the highest safety standards.
Design Considerations
As the ultimate safety equipment these towers should
be designed to cover all applicable potential hazards:
 earthquake
 snow
 storm
 tornado
 hail and/or icing
 aircraft impact
 explosions
 fire
 missiles
 internal flooding
 loss of make-up water
 power supply variation (Hz, V) or complete loss
 mechanical failures
The consideration of these hazards in the design leads
to several hundred special technical qualifications for
the construction and equipment. HAMON engineers in
close contact with authorities and owners have worked
out these requirements and the solutions.
Concept of Emergency Cooling Towers
For new applications HAMON recommends in general
Emergency Cooling Towers
 being built of small cellular modules in reinforced
concrete with forced draft fans
 with up to 4-fold redundancy
 with water storage of minimum 2 days
 which consider the applicable hazards and are designed
for extreme climate conditions
 which integrate in the housing the additional equipment
like pumps, piping, valves, electrical, etc.
 almost completely built of non flammable construction
materials
For existing plants, the technical solution must be
developed according to the actual needs and situation.
References
HAMON has delivered emergency cooling towers for
new and already existing power plants.
The Emergency Cooling Towers of NPP Civaux (EDF,
France) and GKN II (EnBW, Germany) are in addition to
other very good examples of this safety philosophy and
have determined the state-of-the-Art. Further they are a
demonstration of HAMON’ competence in this field.
References for upgrades of existing plants are:
 C.N. ASCO, Tarragona Spain
 C.N. Trillo, Guadalajara, Spain
 C.N. Vandellos, ANAS, Tarragona, Spain
HAMON Engineers are available to discuss the application of an Emergency Cooling Tower for your nuclear
power plant.
By integrating an Emergency Cooling Tower into the nuclear cooling circuit the owner
 increases the safety of the plant to ‘State of the Art’ by closing a gap in safety
 increases the likelihood for acceptance by Authorities, Governments and the Public
 saves the creation of an artificial private huge pond with its everlasting maintenance and surveillance
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