Transcript CNS Country Group Presentation Template

6th Review Meeting of the
Convention on Nuclear Safety
SLOVENIA
Country Group 3
24 March 2014, Vienna
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Outline
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Basic information on the national programme
Changes in the legislation since the last Review
Meeting
Significant events since the last Review Meeting
Action on challenges and planned measures from the
last Review Meeting
Current Challenges
Questions Raised from Peer Review of National
Report
Updates to National Report to 6th Review Meeting
Conclusions
Basic information on the national
programme
Nuclear Slovenia
Mine
TRIGA
NPP Krško
Krško NPP
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Westinghouse PWR, 2 loop
700 MWe
Commercial operation since
1983
Ownership 50:50 SloveniaCroatia
Without major problems
Life time extension after
2023 is foreseen
Intensive post Fukushima
improvements
Other facilities
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TRIGA research reactor
Central Interim RW Storage
Former Uranium Mine
Looking for the LLIW Repository
>1000 sources of ionizing radiation
Slovenia, the smallest nuclear
country
We have everything the big country has …
… but we have to manage it with less
resources!
Dynamic period!
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Krško NPP operation was without major
problems, however ...
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... 11. March 2011 has drastically changed
the focus of nuclear safety related activities
Post-Fukushima activities
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New mobile equipment’s
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Mobile DG’s - various power (from 3 KW up to 2 MW)
Mobile Air Compressors
Mobile FP pumps
Stress tests and National Action Plan
Long term improvements:
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Comprehensive Safety Upgrade Programme:
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Filtered Containment venting – implemented
Passive Autocatalitic Recombiners – implemented
Additional SI and FW pumps – by 2018
Additional heat sink – by 2018
External control room – by 2018
Dry spent fuel storage – by 2018
Fire Equipment
Fire truck with a hydraulic fire-fighting arm
Tanks: 8500 l of water & 1500 l of fire-extinguishing foam
First actions of the Krško NPP
30 m3/hr, 32 bar
2 discharge connections
Testing the spraying of
the “imaginary SFP”
First actions of the Krško NPP
Fuel (diesel,
gasoline) stored
on-site
Mobile and portable
diesel generators
Other improvements
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3rd safety related diesel generator
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Upgrade of flood protection dikes.
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Reduces risk primarily from the Station Blackout
Sequence and from seismic events
Protects against more demanding Probable
Maximum Flood
Reactor pressure vessel head replacement
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In response to industry events involving Alloy 600
penetrations and 82/182 weld material
Safety Related Diesel Generator
Other developments
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Aging management programme approved
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It makes operation after 2023 possible
One more Periodic Safety Review have to be
done before first 10 year life extension
Second Periodic Safety Review is concluded,
to be approved by June 2014
KI iodide tablets distributed in 10 km radius
around the Krško NPP.
Improvements in the plant
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Replaced main generator rotor
Upgraded of 400 kV buses and undervoltage
protection
Replaced main feedwater isolation valves
actuators
Upgraded fire protection detection system,
Refurbished residual heat removal and
essential service water systems.
Post Fukushima actions
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Operator immediately started with improvements
The SNSA issued three decisions to the Krško NPP:
 to perform an extraordinary PSR in line with
specifications for European Stress Tests
 to reassess the severe accident management
strategy and implement safety improvements for
prevention of severe accidents and mitigation of
its consequences
 to review bases for emergency planning and
response including emergency planning zones
Stress tests analyses
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Evaluation of seismic and flooding margins,
Additional station blackout analyses,
Drain cycle of the 1E batteries,
Water heatup and evaporation rate in the
spent fuel pool,
Evaluation of spent fuel pool criticality.
Stress test conclusions
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Krško NPP was well designed and
constructed,
Potential external events were taken into
account during preparation of protective and
mitigating measures.
A single recommendation after Peer Review:
“The regulator should consider requesting to update
the seismic design basis for future design
modifications and consequently the associated PSA
model.”
Post Fukushima Action plan
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Its core is the Krško NPP’s Safety Upgrade
Program
Implementation of upgrades foreseen already in
2009
Implementation of Short-Term Improvements
(accelerated B.5.b Requirements Actions):
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Procurement of AC diesel generators, pumps and
compressors, implementation of quick connection points for
this equipment, additional fire protection equipments,
including high capability fire truck
Amendments to the emergency operating procedures and
severe management accident guidelines
Krško NPP Safety Upgrade
Programme
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Safety upgrade of AC power,
Additional FW pump,
Additional heat sink (AHS),
Additional SI pumps with a dedicated water
supply,
Containment filter vent system and passive
autocatalytic recombiners,
Emergency control room,
Fixed spray system around the spent fuel pit,
Krško NPP Safety Upgrade
Programme (cont’d)
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Mobile heat exchanger with provisions to
quick connect,
Flood protection upgrade,
New technical support center,
Upgrade of existing operational support
center.
Changes in the legislation
Changes in the legislation since the
last Review Meeting
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New Act on Liability for Nuclear Damage issued
Amendments of the Act on Ionising Radiation
Protection and Nuclear Safety comprising:
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requirements of Nuclear Safety Directive,
the restriction of the right to go on strike,
provisions on physical protection,
duplications in the area of radiation practices,
availability of inspectors and professional officers, etc.
Resolution on Nuclear Safety
Significant events since the last
Review Meeting
Events in the Krško NPP
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Activation of false alarms in the seismic
monitoring system,
Inoperability of the service water system,
Trip of auxiliary feedwater pump,
Inoperability of Chilled Water System,
Reactor vessel head cable bridge incident,
Extensive fuel damage
Reactor shutdowns
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Reactor trip and safety injection actuation
system due to the loss of external load
Main steam isolation valve stem failure
Shutdown due to large amounts of debris in
the Sava river
Malfunctioning of primary temperature
measurement system
Trip due to the loss of external load
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23 March 2011 (during Fukushima!)
Spurious activation of bus protection in the
NPP’s 400 kV switchyard,
Rapid pressure decrease in the main steam
line,
Safety injection (SI) signal on low steam line
pressure,
Diesel generators started automatically,
No other problems
Trip due to steam isolation valve
stem failure
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25 February 2013
Sudden closure of main steam isolation valve
(MSIV) – valve stem break,
Increased steam flow in another line resulted
in pressure drop actuating the safety injection
system and the reactor trip,
Similar event occurred 1997,
Replacement and redesign of MSIV.
Trip due to steam isolation valve
stem failure
Broken MSIV stem
Shutdown due to debris in the river
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28 October 2012
The flow of the river Sava rose very rapidly
High river washed down materials from river banks,
The inlet of the condenser cooling system was
clogged,
Condenser cooling water flow was reduced,
Temperature and pressure in the condenser
increased and vacuum in the condenser
deteriorated.
Operators carried out manual preventive shutdown
of the reactor.
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Trip due to the malfunctioning of the primary
temperature measurement system
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Extensive fuel damage
See last part of this presentation with updates to the
National Report
Action on challenges and planned
measures from the last Review
Meeting
Problems of domestic TSOs – Reliance
on foreign TSO
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Not all technical aspects could be covered by
domestic Technical Support Organizations
(TSOs)
Operator is seeking expertise from anywhere
Reducing number of domestic experts
No systematic support to nuclear fission
related research, experts are growing older ...
Challenge remains!
Financial and Human Resources for
the SNSA
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SNSA is financed only by the state budget,
Due to the crisis funds are decreasing,
No new employments!
SNSA had to abandon ISO9001 certification
SNSA is fulfilling its mission, but ...
... has already publicly announced what risks
are increasing due to restrictions
Challenge remains and is growing bigger!
IRRS in 2011
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Between 25 September – 4 October 2011
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The SNSA Strengths
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Adequate legal framework
SNSA has in place an effective process for carrying out this
responsibility,
Response to the accident at the TEPCO Fukushima Daiichi
power plant has been prompt and effective.
Good practices
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SNSA’s quality management system,
An inter-ministerial committee chaired by SNSA for coordination
of emergency planning
Communications system used during emergency situations
IRRS in 2011
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A need to develop a national policy and strategy for
nuclear safety - done
Possible alternative methods of financing SNSA –
decided not to go for independent agency!
SNSA needs competencies and resources – see
previous challenge
Necessary steps to be taken for the Low and
Intermediate Level Waste Repository – SNSA has
actively pushed for it, some progress
Transition between the emergency phase to long term
recovery operations and the post-accident phase,
... and some others.
Reactor Head Replacement
Done in 2012!
Upgrade of Flood Protection and
Installation of New Diesel Generator
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Done in 2011-12!
Flood protection
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Upgrade by up to 1.8 meters of flood protection dikes
along the river Sava.
Seismic criteria the same as for the Krško NPP
Safety margin of 0.75 m.
Third Diesel Generator
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Class 1E 3.5 MW diesel generator
Increases safety in case of a seismic event and loss of offsite
power.
Upgrade of flood protection dikes
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Plant site
would
remain dry
Upgrade of dikes upstream of the plant to protect the plant to the flood flows
beyond the Probable Maximum Flood
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Harmonization of Legislation with
Good Practice in EU
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WENRA Reference Levels are fully
transposed into Slovenian legislation,
Slovenian legislation is harmonized with the
EU Nuclear Safety Directive and EU Nuclear
Waste Directive
The Krško QA System and
Compliance with IAEA GS-R-3
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The latest revision of Quality Assurance Plan in 2011.
In line with Slovenian Rules JV5 and IAEA GS-R-3
requirements
Covers Safety Culture, Self-Assessment, Human
Performance, Industrial Safety
The bases for the revision were:
 Changes of the Slovenian regulatory requirements
and licensing documents,
 SNSA inspection requirements,
 Changes of international standards,
 Conclusions of the first PSR,
PSR 2 to be completed in 2013
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PSR2 was completed
There were no major issues which would prevent
further safe operation
15 safety factors were reviewed
An action plan is being developed and will be
implemented in the next 5 years.
Some issues from the action plan:
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Procedures periodic review
Root cause analysis
Temporary modification survey
Generation of solid radioactive waste
Potential tube wear from secondary side loose parts
...
Cyber Security Threats and Airplane
Crashes
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Krško NPP has prepared and implemented Cyber
Security programme
SNSA has trained its people
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Airplane Crashes
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No-flight zone in place around the NPP Krško
NEI 06-12 B.5.b requirements was one of the inputs to post
Fukushima action plan and those consider also airplane
crash
Bunkerized structures for DG3 and future safety equipment
Alternative Spent Fuel Pool cooling system,
Fire fighting of airplane fuel fires capabilities
Improved SAMGs.
Future Planned Measures
to Improve Safety
Future Planned Measures to Improve
Safety
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Most of those measures are within the Safety
Upgrade Programme (see post-Fukushima
related slides)
Upflow conversion in the reactor vessel
Improvements in off-site emergency planning
together with Croatia
Inviting peer review missions:
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WANO, IRRS-FU, OSART, EPREV
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Current and Future Challenges
Challenges
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Individual actions of the Safety Upgrade
Program as well as other National postFukushima Action Plan (NAcP), including Design
Extension Codition (DEC) implementation
Reassessment of alternative spent fuel strategy
(part of NAcP)
Preservation of knowledge and competencies:
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Financial and Human Resources of SNSA
Domestic TSOs
Questions Raised from Peer Review
of National Report
Questions from Peer Review
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The complete set of answers to the questions raised by
other CP is available at the SNSA site:
http://www.ursjv.gov.si/fileadmin/ujv.gov.si/pageuploads/si/Porocila/
NacionalnaPorocila/KJV_6th_answers.pdf
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Questions were evenly distributed among articles, with
the exception two:
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“regulatory body”: the decreasing SNSA budget, challenge to
keep competency due to small nuclear programme, ageing of the
SNSA staff, sharing information to the public of the SNSA
activities
“assessment and verification of safety”: PSA, PSR, SAMG,
response to Fukushima, performance indicators,
Questions from Peer Review
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The other questions referred to.
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Post-Fukushima upgrades (plan and status)
Management system of the licensee
Emergency preparedness in Slovenia and Croatia and
review of emergency plans in the light of Fukushima
Incident reporting system by the operator
Assessing safety culture
Transparency and communication to the public by the
licensee
Updates to National Report to
the Review Meeting
Fuel leakage and cladding failure
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Discovered during outage in October 2013,
Six fuel assemblies were leaking,
50 cm long segment of the fuel rod found in the
fuel transfer channel
Fuel leakage and cladding failure
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Open defects in 8 fuel rods of three fuel assemblies,
Primary cause debris fretting, baffle jetting and gridto-rod fretting
Extensive inspection of fuel assemblies and the core
baffle plate
Corrective action: armoring of fuel assemblies with
dummy stainless steel rods at exposed positions
Prior to the start of operation an extended Failed
Fuel Action Plan was prepared
RTD – Spurious electrical signals
caused reactor trip
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Resistance Temperature Detectors Bypass was
eliminated during outage 2013
After the outage signal “spiking” caused reactor trip
due to creation of OPΔT (for a split second)
Corrective actions:
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Installation of “surge suppressors”
Some equipment was tagged out until the problem was
resolved
The vendor will analyze lead/lag filters used in processing the
signals and redesign appropriate circuits
CONCLUSIONS
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The only NPP operating safely
Slovenia has Legislative System harmonized with
best practices
Regulatory Supervision is efficient and effective,
although the risks due to lack of resources are
increasing
Slovenia and its Nuclear Facilities
fulfill requirements of the
Convention on Nuclear Safety