Aftermath of the INES-3 Incidentat Paks NPPon 10th April, 2003.
Lajos Vöröss
Hungarian Atomic Energy Authority
7th Annual Meeting of NERS
IAEA, Vienna, 23-24, September 2004.
2
3
Main Tasks to Perform
After having stabilised the situation inside thereactor hall there have been two main tasksto perform:
1. Recovery of service shaft No.1 of Unit 2. (SS) where theincident occurred
2. Restart of Unit 2. as soon as possible
4
- Recovery project and team established at Paks NPP
- Tendering process won by Russian consortium led byTVEL; FRAMATOM had bidden as well
- 6-8 months preparatory, 2-3 months implement phasesplanned, excluded licensing time - significant delay now
- Special tools for manual removal of debris are to beused
- Manipulation is to be carried out from a movableplatform placed above the cleaning tank
- Some experiments to clarify behaviour of debris forplanned removal actions performed
Recovery of SS
5
Recovery outline – FRA/ GER
crane
air filter
manipulator
working rod
suction
control panel
container
cleaning tank
2 versions
•removal of the cleaningtank and fuel in one step(dismissed later –difficult, does not givefinal solution)
•removal of the cleaningtank and fuel in partswith clips, bending tools,manipulators, vacuumsoakers, cutters
6
Recovery outline –RUS
shell
container
different
- water level,
- boron
concent-
ration,
- contami-
nation
ГИ ВНИПИЭТ
ГП НИКИМТ
ПО Маяк
НПФ Сосны
structure
winner
mostlymanual
removal
moving
platform
7
- 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
Recovery of SS (cont’d)
8
Recovery of SS (cont’d)
- Reliable neutron flux and boron concentrationmeasurement in SS installed
- Increased radwaste storage capacity constructed
- Free positions made available for capsules/cartridgescontaining debris in spent fuel pool
- Preparatory actions for regulatory licensing process
- regulatory requirements for recovery developed
- review and assessment in large number ofmodifications and fabrication of equipmentperformed
9
Restart of Unit 2.
- After long-term shut-down status with intact main equipmentbut contaminated by uranium and trans-uranium isotopes -special cleaning was necessary (completed)
- Interrupted refuelling and maintenance occurred during theincident
- RPV used as temporary storage tank of spent fuelassemblies
- Low enrichment fresh FE supply and rearrangement of spentfuel pool became necessary
- Reuse of cleaned spent fuel assemblies is limited
10
Restart of Unit 2. (cont’d)
- Conception for short term operation cycle developed
- refuelling and yearly maintenance completed
- suitable core for operation during the preparatoryphase of the recovery is possible (about 4 monthslong)
- regulatory requirements for restart/operation phasesdeveloped, licence given on 16. July, 2004.
- nearly full power operation started on 02 Sept. 2004.
- Keen interest from media and public follows
11
International Assistance
- IAEA - two international missions provided at Paks NPP
- GAN (Russian Regulator) - on basis of contractualarrangement, focuses to review QA of Russiancontractors
- US NRC/IAEA - gives advice to review conditions ofrestart of Unit 2.
NOTE: In spite of the incident, lifetime extension andpower uprating of the units are still insisted on