Events at Fukushima NPP in Japan
New impetus to review NPPs safety worldwide
INES Level 7
Impact of
extreme external
events and their
combinations
2
KNOWLEDGE
BASE
TECHNOLOGY
(technical safety
ensuring)
DEFENCE-IN-DEPTH
PRINCIPLE
Multiplicity of safety
barriers
Variety of levels for
protection barriers:
–prevention of accidents
–mitigation of accident
consequences
(accident management)
LEGISLATION
Federal laws
(responsibility
principles)
System of rules and
regulation
State licensing
authority
(independent
regulation)
SAFETY CULTURE - Alignment of priorities
- Human factor
Safety fundamentals
3
The safety fundamentals are correct and shall
not be subject to any revisions
Prolonged loss of external and internal
power and water supply
Failure to provide
external support timely
Inefficiency of the severe accident
management efforts made by personnel
Very low probable events and
their combination (deterministic
approach)
Off-site
radiological
impact on the
public and the
environment
shall be
excluded
4
The key criterion of success
is the recovery of power
supply and water feed for
reactor cooling down
implemented within first
hours after the total blackout
Operating organization, governmental and local
authorities, international organizations and the public
shall be timely informed about a NPP event. Provision of
external support from state level as well as from
international community shall be ensured.
At each power unit there
shall be available a reserve of
engineering means protected
against possible damage by a
natural disaster, which ensure
power and water supply for
purposes of reactor and fuel
pool cooling
Personnel, managers at NPP and in the Operating
organization shall be focused on prompt actions
aimed at accident prevention and mitigation of severe
accidents consequences
!
6
Deterministic experience related to BDBA consequences
evaluation that has been accumulated beforehand
Additional equipment failures
Methodology for Russian NPPs safety
status analysis as regard to emergencies
Upgrading works aimed at safety improvement of NPPs
(incl. BDBA management) have been implemented
during last 10 – 15 years
Vulnerabilities and list of hypothetic initial events have
been identified for each NPP
Implementation of supplementary measures aimed at
enhancement of NPP capability to operate in a
standalone mode (up to 5-10 days) is needed
The countermeasures considered in designs of the
operating NPPs cover not all BDBA initial events
(combination of 2 or more failures was not considered)
7
Analytical report on the reviewed scenarios of
abnormal external event impacts on Russian NPPs;
Measures aimed at mitigation of beyond-design-
basis accident consequences at NPPs:
Operative (1 to 4 months);
Short-term (1 year);
Medium-term (1 to 2 years);
Long-term (3 to 7 years)
8
9
Reviews of safety status with involvement of General Designer, Architect Engineer and Scientific Supervisor have been performed for all operating NPPs in Russia with all credible extreme events. For each NPP a separate report has been elaborated.
Supplementary safety improvement measures have been developed for each NPP
The reports on safety analysis of a NPP under extreme external impacts had been submitted to the regulatory body (Rostechnadzor) till 15.08.2011
As per results of own review, Rostechnadzor had approved the reports on safety analysis of a NPP under extreme external impacts in November 2011
Operative measures
Focused checks and analysis of NPP safety provisions for extreme impacts
Extraordinary plant staff emergency drills as per BDBA scenarios
Extraordinary tests of safety systems equipment with EDG start-up
Increased number of regularly performed emergency drills related to personnel actions in case of a BDBA
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Short-term measures
To identify backup (additional) water (borated water) sources for purposes of heat removal from the core, fuel pool and SNF storage facilities, and to introduce procedures of their use into the operating documentation
To develop a generic list of supplementary mobile equipment per a unit
To perform additional quick studies and analysis of NPP seismic zoning documentation, and calculation analysis of seismic impacts on the reactor unit, fuel pools and on-site SNF storage facilities
To perform analysis of emergency instructions and guidelines as regard to sufficiency of accident management actions to be performed by staff
To elaborate technical specifications on the supplementary design solutions
11
Supplementary equipment delivery to NPPs
Full-scope implementation of the supplementary design solutions
Long-term measures
Medium-term measures
Adjustment of emergency instructions and accident
guidelines after implementation of the planned measures
Development of the design documentation and
beginning of implementation of the supplementary design solutions
Adjustment of emergency instructions and accident
guidelines after the equipment delivery to NPPs
Development of severe accident management guidelines 12
Generic set of mobile equipment for BDBA management
purposes, per a Unit
29%
89%
20%
74%
71%
11%
80%
26%
Mobile Diesel
Generator Units
(MDGU) 2.0 MW
Mobile Diesel
Generator Units
(MDGU) 0.2 MW
Mobile Pump
Units (MPU)
Motor-driven
Pumps
Supplied
May 2012
80 pcs.
35 pcs.
36 pcs.
31 pcs.
(9шт.) (22 шт.)
(59 шт.)
(32 шт.)
(7 шт.)
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To identify supplementary schemes of power supply from emergency diesel generators to the loads:
power control;
control systems.
To identify supplementary water sources and schemes of water supply to reactor, steam generators and SNF storage pools using diesel-driven / motor-driven pumps;
To implement a system for SNF pool metal liner cooling.
Implementation of hydrogen monitoring and afterburning systems;
Implementation of a system for emergency gas release from the reactor containment.
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Power supply securing
Heat removal securing
Explosion safety ensuring
Provision for reactor scram by the automated emergency
protection system in case of earthquake;
Improvement of seismic resistance of plant equipment,
pipelines and civil structures.
NPP equipping with emergency I&C devices designed for
operation under BDBA conditions;
Improvement of protection of plant MCRs and ECRs;
Development of Severe Accident Management Guidelines.
15
Seismic resistance ensuring
Provisions for management and control
Upgrading the communication
infrastructure of the Engineering Support
Center, the Crisis Center and NPPs;
Establishment of a regional Crisis Center of
WANO Moscow Center.
16
Analysis of scenarios and radiological consequences of
severe accidents, with the goal of implementation of:
• the RPV cooling system;
• the system for emergency gas release from the reactor
containment;
• the emergency I&C;
• other supplementary design solutions.
Calculation of maximum possible seismic impacts at the NPP
locations, on the basis of modern computational models.
17
Federal safety requirements are met with the
compensatory measures taken into account;
For Russian NPPs in operation, analysis of their
defense-in-depth resistance has been carried out;
Measures aimed at enhancement of operating NPPs
resistance to extreme external impacts have been
developed and are implemented;
For Russian NPPs under construction or in designing,
it is planned to perform analysis of their resistance to
extreme external impacts.
18 Final slide
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