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http://www.ursjv.gov.si/

REPUBLIC OF SLOVENIAMINISTRY OF THE ENVIRONMENT AND SPATIAL PLANNINGSLOVENIAN NUCLEAR SAFETY ADMINISTRATION

4th CNS Review Meeting, Vienna, 15 April 2008

4th Review Meeting of theConvention on Nuclear Safety

SLOVENIACountry Group 6

Vienna, NH Hotel, 15 April 2008

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Outline

• Nuclear Safety 2005-2008

• Legislative arrangements

• Regulatory supervision

• Issues from 2005 (Follow-up)

• Questions 2008

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Nuclear Slovenia

NPP KrškoTRIGA

Mine

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Slovenia, the smallest nuclear country

We have everything the big country has …

… but we have to manage it with less resources!

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Nuclear Facilities

Highlights/Themes of 2008 Report

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Krško NPP

• Westinghouse PWR• 2 loop• 700 MWe• Commercial operation

since 1983• Ownership 50:50

Slovenia-Croatia


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Krško NPP: Operation

• Without major problems• Last reactor trip in 2005• 18 month fuel cycle


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Krško NPP: Performance Indicators

Load Factor

0

20

40

60

80

100

120

1983

1984

1985

1986

1987

1988

1989

1990

1991

1992

1993

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

2007

avg.

year

[ %

]


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Electrical Energy Production

0

1

2

3

4

5

6

1983

1984

1985

1986

1987

1988

1989

1990

1991

1992

1993

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

2007

avg.

year

[TW

h]


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Number of Reactor Trips

0

2

4

6

8

10

12

14

16

1983

1984

1985

1986

1987

1988

1989

1990

1991

1992

1993

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

2007

avg.

year

num

ber

of s

hutd

owns

Manual Auto

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Collective Dose

0

500

1000

1500

2000

2500

3000

year

[man

mS

v]


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Unavailability of Auxiliary Feedwater

0,000

0,001

0,002

0,003

0,004

0,005

0,006

0,007

0,008

0,009

1991

1992

1993

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

2007

avg.

year

unav

aila

bilit

y


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Krško NPP: International Reviews

• OSART Follow-up (November 2005)

• Overall impression was positive. – Majority of issues fully resolved.– Commitment for improvements,– Priority remains on nuclear safety at all levels,– Effective use of computer technology.

• Areas for improvement:– Industrial safety should be improved.– Volume and storage of low level waste.– Enhancing the use and adherence to procedures in the

field.


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Krško NPP: Issues

• Extension to 18-month fuel cycle– Foreseen already in 2000 during SG replacement– New fuel with 1.4X IFBA burnable absorbers– 2004 – first extended cycle was 19 months long– Only few operational problems with fuel leaks– Increase in tritium production

• Emergency preparedness exercises:– Annual exercises in the Krško NPP with the participation

of the SNSA– Slovenia participated in “CONVEX-3” exercise in May

2005 organized in the Cernavoda NPP


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Krško NPP: Finances

• Operator must ensure sufficient financial resources throughout the operating lifetime.

• Owners of Krško NPP are approving 5 years investment plan

• No problems with any delayed payments in recent years.


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Krško NPP: Human Resources

• Krško NPP staffing– Approaching the period of retirements– Active employment policy– Currently 570 staff members– No plans for bigger reductions


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• Systematic Approach to Training• Retraining of licensed personnel (typically 4 per

year), two-year cycle of requalification training • Full-scope replica simulator:

– Abnormal Operating Procedures validation– Unusual events analysed, corrective actions proposed – Validation of some scenarios in the scope of the Periodic

Safety Review recommendations in 2006

• Training for subcontractors (General Employee and Radiation Protection)


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• Training for specific areas: Refuelling Operations, Maintenance, Engineering, Radiation Protection, Chemistry, Security, Emergency Preparedness

• Maintenance training centre• SNSA and TSO training:

– two months of initial training on nuclear technology in Ljubljana,

– the US NRC Training Center in Chattanooga, USA,– the Krško NPP - classroom training and simulator

training,– international courses and workshops


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Krško NPP: QA and Safety Culture

• QA and ISEG merged• “Quality and Nuclear Oversight Division”

responsible for :−Design Modification Control, Procurement

documents control, QA review of Plant Procedures, Document Control, Procurement control, Control of special processes, Inspection control, Audits,

−Self-assessment program, Safety culture oversight, Human performance oversight, Operating experience oversight, Corrective Action Program

• Safety Culture review


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Krško NPP: Major modifications

• Computer program PAD 4.0 for fuel elements design basis calculation.

• Beacon-TSM application as a Power Distribution Monitoring System (PDMS).

• Replacement of a traveling screen for the service water pump suction.

• Replacement of fire alarm annunciators, pipelines, isolation valves and the hydrant on the fire protection system.

• Replacement of the central alarm system. • Old 10 kV distribution grid replaced by a 6.3 kV

house grid.


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Krško NPP: Major modifications

• Replacement of the water pre-treatment and the water treatment system.

• Installation of a super compactor,• Installation of a preheating and pressure side venting of

heater drain system,• Replacement of two low pressure turbine rotors, stators

and bearings with better thermo-hydraulic efficiency (about 3%),

• Installation of seismic protection equipment on the polar crane in the reactor containment building.

• Chilled Water System Chiller Replacement,• Reactor building recirculation sump strainer

replacement,• Replacement of thermal insulation inside the containment.


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Krško NPP: Major future modifications

• Under construction: A new cooling tower

• Announced: Digital Electro-Hydraulic Control System – DEH

• In preparation: Installation of the third emergency Diesel Generator DG3


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Krško NPP: Problems

• Disintegration of an AF flow distributer in SG• Increased AF and IB room temperature • Warming of Ultimate Heat Sink - Sava river


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Disintegration of AF flow distributer in SG

Two loose parts found during outage 2007 in the secondary side of steam generator

Disintegrated AFW flow distributor (vanes, 150x70x20mm) ~50 U tubes had marks of mechanical damage, 16 U tubes were

plugged AF flow vanes also exhibited cracks also in another steam

generator Both flow distributors replaced


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Increased AFW Room Temperature

• In summer temperature in turbine drive auxiliary feedwater pump raises above maximum allowed.

• Four times between 2002 and 2005• Special analysis established that equipment can

withstand 46°C.• Maximum allowed temperature increased from

40 to 46°C • Issue will be addressed through Aging Program

and Maintenance Procedures


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Sava River high temperature

• River Sava temperature is warmer every summer!• Approaching ultimate heat sink limit temperature!• Actions:

– improved Service Water System pumps characteristics in 2002 and 2004

– temporary Justification for Continuous Operation up to 27,4oC

– modification of Chilled Water System underway (air cooled)

• Remains an open issue


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Resolution of sump clogging issue

Slovenia closely followed US NRC GL 2004-02 requirements

Isolation at lower levels and critical points replaced with metal reflecting isolation

Sump screen/strainer replaced – new one with 300+m2 area, 1.6 mm diameter mesh

Procedure for control of materials in containment in place


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Krško NPP: Tritium issue

• Tritium releases problem after introduction of 18-month fuel cycle.

• In 2006 the quarterly release limit of 8 TBq exceeded.

• Tritium contributes to annual effective dose <10 nSv.

• SNSA increased annual limit from 20 to 45 TBq and halved the limit for other liquid discharges


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Krško NPP: Issues from outside

• Hydro Plants• Airport


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Krško NPP: Issues from outside – Hydro Plants

Chain of HPPs under construction on river Sava up and downstream of NPP SNSA is setting conditions for these constructions

Reassessment of external flooding hazard to the Krško NPP: probabilistic assessment of floods – Q(10.000) values higher

by 12% some deficiencies in flood protection dikes identified probable maximum flood (PMF) analysis according to

ANSI/ANS-2.8-1992 underway - PMF values higher for 35-50% flood analysis for HPPs dam failures according to ANSI/ANS-

2.8-1992 is underway Krško NPP protection against flooding needs to be

upgraded At the same site are planned radwaste repository and a

new NPP


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Krško NPP: Issues from outside – Airport Cerklje

• Airport Cerklje in the vicinity of NPP Krško will be expanded

• In- and out-going air traffic will increase• Air exclusion zone (r=1km, h=5000ft) around NPP

remains in force• Military facilities at the airport will be refurbished

and expanded with civil aviation• A study into possible effects to NPP Krško is

underway • Decrease in nuclear safety will not be allowed


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The second NPP unit

• Planned since July 2006• Should go on-line 2017• Project has not started yet

• It will most probably be a PWR at the same site• The GEN-energija utility will be the investor


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Siting of new NPP


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“Simplicity” of the process

Many players:• Government• Ministry of

Environment• Ministry of Economy• SNSA• …

Several Laws:• Spatial Planning• Protection of Nature• Construction• Mining• Nuclear Safety

Licenses, legal procedures

Facilit

y

typ

e

NPP


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SNSA’s role

Siting

Trial operation

Operation

End of operation

Decommissioning

Construction


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Other facilities

• TRIGA research reactor

• Central Interim RW Storage

• Former Uranium Mine

• Looking for the LILW Repository

• >1000 sources of ionizing radiation

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Low and Intermediate Level Repository

• Three repository options studied for a site close to the Krško NPP.

• Site is not perfect – problem of floods

• Underground silos proposed

– ~55 m deep and 30 m diameter built from the surface,

• Public hearing and acceptance process is underway

• Should be finally accepted by the Government.

• Possible expansion for Croatian half of waste

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Legislative Arrangements

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• Act on nuclear safety from 2002• 22 decrees and regulations• Several older still valid• Intensive involvement in WENRA process• Two regulations will harmonize with WENRA

– On nuclear safety design bases, documentation and licensing

– On operational nuclear safety

• Being discussed, adopted 2008 or 2009.

Legislative and Regulatory Framework

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Regulatory Supervision

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• SNSA - within the Ministry of the Environment and Spatial Planning

Slovenian Nuclear Safety Administration SNSA

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SNSA within the governmental structure

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SNSA:

• 46 staff positions. – 9 Ph.D.– 14 Master of Science– 20 Graduated Engineers– 3 Technical Staff

• Annual budget about 2,7 mio EUR

• Independent in its professional decisions.

• Licensees may appeal to the Ministry of Environment

• Drafts regulations or decrees

• Issues individual legal acts - decisions to the licensees.

• Independent inspection

SNSA ID

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SNSA: • December 2007: ISO 9001:2000 certified

SNSA Management System

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SNSA Integrated Assessment System

NPP

Inspections

Rumors

Licensing ofChanges

SNSA Management Meeting(daily)

Feeling about the Climate in the NPP

Third PartyNews

BAD

Reporting Managementmeetings

Safety Indicators

Outages

OEF Analyses

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SNSA System of Safety Indicators


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SNSA Fuel Cycle and Outage Analysis

OU

TA

GE

Inspection of maintenance activities

Inspection of modifications

Inspection of tests

Formation of SNSA review team

Preparation of review plan

Draft of Outage analysis report

NPP's Outage plan

Co-ordination with NPP and TSOs

Daily meetings and drafting of report

Finalization of the report with the Action plan

Revision of the report with the Action plan

Implementation of the Action plan

Transfer of not fully implemented actions into new cycle

Archiving

+15 d

+30 d

During fuel cycle

-30 d

-30 d

-60 d

-6 m

SNSA TSOs

TSO's report

SNSA

SNSA

SNSA

NPP

SNSA

SNSA

Comments of TSOs and NPP

SNSA

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SNSA Risk Based Regulatory Oversight

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SNSA Communication Strategy

• First communicate it on technical level trying to “sell the idea”

• If not accepted: increase informal pressure – meeting with the management

• Only after that follows our order (decision)!

(Never in last 5 years!)

Regulatory Gun

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Good Practices

• Krško NPP: – Long term (5 yrs) investment plan approved (gives

flexibility for nuclear safety maintenance)

– Dedicated training programme for field operators developed, “motor operated valves” training center

– Corrective Action Programme (CAP)

– Resolution of sump clogging issue

• SNSA – ISO 9001 certified

– comprehensive outage inspection programme,

– Risk Based Oversight

– Plant Performance Indicators

Good practices

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Issues from 2005

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Challenges

• Pressure of owners to reduce operating costs Owners approved kWh price: covers production + investments. Long term stability guaranteed

• SNSA Projects – Managing of ageing processes in the Krško NPP

Internal SNSA system developed and used

– Plant event analysis by the regulatory bodyRegularly performed

– Review of NPP Krško Safety Culture and guidelines for regulatory evaluation of Safety Culture

Partly done: “soft system” established, more formal developed

– Development of PSADone, being used!

Follow-up from 3rd Meeting

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Challenges

• Siting of LILW repository Site in Krško community waits local approval this year

LILW operational by 2013

• Decision on high-level RW No change – decision to be taken after 2020

• Agreement about repository between Slovenia and Croatia

No news, maybe after Slovenia gets a site


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Challenges

• Qualification of domestic subcontractors Qualifications of authorized experts

Postgraduate studies, research support, European cooperation- EURATOM projects,

Strengthening education in the nuclear areas

Targeted research programmes

• Quality Management System Krško NPP Quality Assurance Plan meets criteria of

10CFR50 Appendix B and 50-C/SG-Q and is constantly upgraded


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Challenges

• Notification of Neighbouring Countries in Nuclear Emergency Austria, Hungary, IAEA, ECURIE, Croatia would be

notified in accordance with international agreement

Croatia as immediate neighbor is notified from Slovenian Civil Defense headquarters in parallel with the notification of Slovenian responsible authorities

• Installation of a new emergency diesel generator Krško NPP decided to install a Class 1E 3.5 MW diesel

generator by 30.6.2012.


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Planned Measures to Improve Safety

• Action plan for the PSR Completed and approved in 2005,

No major safety issue was revealed, By the end of 2006 20 of the actions were closed, the whole PSR

Actions Plan shall be completed by the end of 2010.

Main closed activities address the potential seismic design problems

• Revised programme of decommissioning and waste disposal Decommissioning programme approved in March 2005, Decommissioning Fund in Slovenia is being managed properly, Croatia started to collect decommissioning funds on a separate

account within the state budget in 2006, In October 2007 Croatian Decommissioning Fund was

established New revision of Decommissioning programme is due in 2009


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Answers to Questions 2008

Selection

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• PSR prioritization process consisted of pre-screening and ranking process. A significant number of issues survived the pre-screening process. All this safety issues were assessed based on a method as described in Haimes’ Risk Modeling, Assessment and Management.

• The new SPSA has shown that in spite of the increased seismic hazard the calculated core damage frequency has decreased due to some seismic upgrades, inclusion of additional systems in the model and revised selected fragilities.

• Operational events caused by inappropriate use of procedures is decreasing (from 3.7% in 2003 to 1.6% in 2007)

• Ageing problems managed by the programs like preventive and corrective maintenance, in-service inspection, in-service testing, environmental qualification and erosion/corrosion program

Questions Raised

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• Deterministic reconciliation of the new seismic hazard: As input free field response spectra determined in first PSHA, scaled to 0.6 g (twice the size of the SSE values) was used. The floor response spectra obtained were very similar to the design floor response spectra. In the original design, peak ground acceleration of the SSE was PGA=0.3 g. It was applied without any reduction at the level of foundation. Based on that and the fact that new PSHA seismic inputs are lower than the values used in seismic PSA (0,6 g) there is no need to reconcile this further in a deterministic manner.

• Number of SNSA staff: Slovenian government follows the policy of not increasing the number of civil servants. In parallel the SNSA has substantially improved its management system and increased the efficiency and effectiveness of its work.

Questions Raised

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• The regulatory and legislative framework is governed only by the Slovenian side, since the Krško NPP is situated on the Slovene territory. The Croatian Nuclear Safety Authority does not participate in establishing regulations.

• SNSA has no human resources department since these issues are handled at the level of the Ministry of Environment

Questions Raised

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• There are no legal requirements for using PSA methods to support Periodic Safety Review. Nevertheless, PSA was used as a supporting tool during the first PSR at the Krško NPP.

• Slovenia does not participate in any large nuclear safety related experimental test programme. Nevertheless the work of OECD/NEA CSNI WGAMA (Working Group on Analysis & Management of Accidents) is followed closely,

• The living PSA is used as a support tool for decision making in introduction of design improvements and modification, planning of activities during plant outages, planning of on-line maintenance, planning of surveillance testing and modifications of plant programmes and procedures.

Questions Raised

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Conclusions

• The only NPP operating safely

• Slovenia has proper Legislative System

• Regulatory Supervision is efficient and effective

Slovenia and its Nuclear Facilities fulfills requirements of the

Convention on Nuclear Safety

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