Aftermath of the INES3 Incident at Paks NPP on 10th April, 2003'

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Aftermath of the INES-3 Incident at Paks NPPon
10th April, 2003.

• Lajos Vöröss
• Hungarian Atomic Energy Authority
• 7th Annual Meeting of NERS
• IAEA, Vienna, 23-24, September 2004.

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(No Transcript)
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Main Tasks to Perform

• After having stabilised the situation inside the
  reactor hall there have been two main tasks to
  perform
• 1. Recovery of service shaft No.1 of Unit 2. (SS)
  where the incident occurred
• 2. Restart of Unit 2. as soon as possible

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Recovery of SS
- Recovery project and team established at Paks
NPP - Tendering process won by Russian
consortium led by TVEL FRAMATOM had bidden as
well - 6-8 months preparatory, 2-3 months
implement phases planned, excluded licensing time
- significant delay now - Special tools for
manual removal of debris are to be used -
Manipulation is to be carried out from a movable
platform placed above the cleaning tank - Some
experiments to clarify behaviour of debris for
planned removal actions performed
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Recovery outline FRA / GER
crane
control panel

• 2 versions
• removal of the cleaning tank and fuel in one step
  (dismissed later difficult, does not give final
  solution)
• removal of the cleaning tank and fuel in parts
  with clips, bending tools, manipulators, vacuum
  soakers, cutters

air filter
suction
working rod
manipulator
container
cleaning tank
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winner
Recovery outline RUS
mostly manual removal
shell
different - water level, - boron concent-
ration, - contami- nation
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moving platform
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structure
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container
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Recovery of SS (contd)

• - Separation of SS from spent fuel pond and from
  other
• systems of Unit 2.became necessary
• - Autonomous cooling device and emergency boron
• injection system for SS have been installed
• - Mobile water cleaning device (NURES,Finland)
  was used
• to clean the water especially from the uranium
  and trans-uranium isotopes

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Recovery of SS (contd)

• - Reliable neutron flux and boron concentration
  measurement in SS installed
• - Increased radwaste storage capacity
  constructed
• - Free positions made available for
  capsules/cartridges containing debris in spent
  fuel pool
• - Preparatory actions for regulatory licensing
  process
• - regulatory requirements for recovery
  developed
• - review and assessment in large number of
  modifications and fabrication of equipment
  performed

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Restart of Unit 2.

• - After long-term shut-down status with intact
  main equipment but contaminated by uranium and
  trans-uranium isotopes - special cleaning was
  necessary (completed)
• - Interrupted refuelling and maintenance
  occurred during the incident
• - RPV used as temporary storage tank of spent
  fuel assemblies
• - Low enrichment fresh FE supply and
  rearrangement of spent fuel pool became necessary
• - Reuse of cleaned spent fuel assemblies is
  limited

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Restart of Unit 2. (contd)

• - Conception for short term operation cycle
  developed
• - refuelling and yearly maintenance completed
• - suitable core for operation during the
  preparatory phase of the recovery is possible
  (about 4 months long)
• - regulatory requirements for
  restart/operation phases developed, licence given
  on 16. July, 2004.
• - nearly full power operation started on 02
  Sept. 2004.
• - Keen interest from media and public follows

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International Assistance

• - IAEA - two international missions provided at
  Paks NPP
• - GAN (Russian Regulator) - on basis of
  contractual arrangement, focuses to review QA of
  Russian contractors
• - US NRC/IAEA - gives advice to review
  conditions of restart of Unit 2.
• NOTE In spite of the incident, lifetime
  extension and power uprating of the units are
  still insisted on