Safety Evaluation Report of Barakah Units 1 and

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SER Summary-CLA Barakah Units 1&2
design basis tsunami was chosen to be outside of the Arabian Gulf, because there are no
sources of tsunamigenic faults within the Arabian Gulf itself. The propagation of the tsunami
inside the Arabian Gulf from a source outside is the result of conservatively chosen
assumptions.
The FANR staff concludes that a further evaluation of a beyond design basis tsunami and
the combination of storm surge and tsunami is warranted in order to understand the increase
that this could cause in run-up at and inundation of the Barakah site. In this context, the
applicant will, using appropriately conservative assumptions and a suitable mathematical
model, evaluate the flooding caused by a tsunami generated by an earthquake at the
Makran subduction zone (outside the Strait of Hormuz) corresponding to a full rupture of this
fault.
The applicant has proposed design changes, including water-tight doors and relocated
penetrations, which will provide protection against flooding well above the flooding level that
would result from a design basis tsunami. The seismic consequences of such a very large
but distant earthquake on the Barakah site ground motion and consequently on the facility
will also be documented along with the need for any additional site or facility protection or
mitigation upgrades.
Other External Initiating Events
The relatively distant location of shipping channels and shallow depths of the Arabian Gulf in
the vicinity of the Barakah site provide ample time for plant operators to implement actions to
prepare for and mitigate the effects of major oil spills. The applicant’s strategy for
addressing extreme toxic gas events, detecting gases, and isolating the control room, is
acceptable. Taking appropriate precautions prior to the onset of sand and dust storms will
ensure that the plant and plant operators are properly prepared to deal with the potential
effects and minimize the consequences of these events. In the limiting case, plant operators
who have been properly trained can ensure that the alternate AC diesel generator is
preserved for use following the event.
With respect to high temperatures, even at temperatures of 50 °C, the Main Control Room
air conditioning system design margins will continue to be maintained. The fire probabilistic
risk assessment will include consideration of extreme fire and flood events in order to assess
vulnerabilities that may need to be addressed. External explosion hazards were evaluated.
An evaluation of margins and a qualitative assessment of the robustness of the
building/barriers against explosions will be later provided.
Consequential Loss of Safety Functions
The reference plant has one alternate AC diesel generator (in addition to the emergency
diesel generators) for two units. The Barakah design currently proposes one alternate AC
generator to be shared among units. FANR has requested the applicant to perform
sensitivity analyses with multiple, diverse, alternate AC generators to establish what
improvements in risk reduction could be achieved. The applicant has proposed to extend
the battery duty life to 16 hours from the design basis value of 8 hours. This provides
substantial additional time for operators to take measures to cope with a station blackout
condition. The applicant has proposed the addition of cross-tie capabilities to provide AC
power for emergency loads from any emergency diesel generator or alternate AC diesel
generator on the site, and the capability to connect a mobile diesel generator to each unit. In
order to fully assess the effects of sand/dust storms or events on the ultimate heat sink and
potential impacts on the various downstream systems being served, further analyses will be
performed as part of the detailed design. FANR has requested the applicant to address low
power and shutdown events in the applicant’s Fukushima Report, including appropriate