Tihange (Belgium)

Map of Tihange

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The Tihange site, situated near Liège at the river Meuse, includes the following installations :

the nuclear generating unit Tihange 1;
the nuclear generating unit Tihange 2;
the nuclear generating unit Tihange 3;
the interim storage building for spent fuel;
the storage building for the (replaced) steam generators;
the training center.

After Belgian spent fuel was no longer allowed to be reprocessed bigger storage capacity became necessary due to the limited storage capacities of the spent fuel pools of the Tihange units. A wet storage building was constructed as an extension to the Tihange 3 installations. The building was put into operation in July 1997.
The wet storage building contained on 31 December 2002 995 fuel assemblies, i.e. about a quarter of the total capacity. It has a total capacity of 3700 assemblies.

Facilities in Tihange

plantreactor typconstruction startoperation startshut down
Tihange spent fuel storagespent fuel pool

During the inspection of a filter of the ventilation system of a part of the NPP gas was accidentally released into the atmosphere. As only 1% of the trimestiral-limit of I-131 was released population and environment were not in danger.


During periodic testing of the emergency power diesel generators, it is discovered that they are not serviceable.
(source: greenpeace nuclear accident calendar)


At Tihange-2 a high collective exposure of a dozen workers took place during the removal of the internal structures from the reactor vessel (37 person-mSv). The individual annual legal dose limit (20 mSv) was not exceeded. This event, due to a lack of work preparation and the nonapplication of the existing ALARA procedure, was classified INES level 1.


One INES level 1 event took place at Tihange-1 in June: simultaneous unavailability of electric batteries due to inadequate operator actions during their periodic testing.


At Tihange 1 in 2002 two INES level 1 events took place: A formal unavailability of an electrical board during about 15 minutes, due to an inappropriate action, and a safety injection in hot zero power conditions at the end of refuelling outage, due to
inappropriate action.


At Tihange 3 in 2002 one INES level 1 event took place: A collapse of the concrete supports of the packing elements of the cooling tower, resulting in the obstruction of the evacuation channel of the circulation water and the overflow of the cooling tower basin, and in an important flooding of some rooms where safeguards systems are located; the unit had to be put in hot shutdown.


At Tihange 2 in 2002 one INES level 2 event took place: A safety injection in hot shutdown conditions (2 hours after the end of the physical testing) due to a spurious depressurisation of the primary water system. The depressurisation was induced by the opening of a pressuriser relief valve due to an inappropriate requalification test of the relief and isolation valves carried out (the test is only allowed in cold shutdown condition, when the pressuriser is empty). The protection system against spurious depressurisation was unavailable in the 3 trains.


At Tihange 1in 2001 two events were classified on INES level 1: an unavailability of one steam generator during the unavailability of the RHRS, and a discovery of the unavailability of a fire protection system.


At Tihange 3 in 2001 three events were classified on INES level 1: a technical specifications violation related to the excessive time between two successive readings of radiation monitoring measures; an unavailability of the emergency make up system of auxiliary feedwater by raw water; and no realization of a test on a filter after its replacement.


At Tihange 1 in 1999 one INES level 1 event occured: During an outage, a verification of the set point of a shutdown cooling safety valve was carried out with an incorrect procedure and an incorrect set point value resulting from an inadequate verification of the subcontractor procedure by the licensee.


At Tihange 3 in 1999 one INES level 1 event occured: During a planned summer hot shutdown, the sampling pump of the radiation monitoring control channel of the reactor building was replaced. The requalification was limited to flow and alarm checks (no leaktightness test) and the control channel was declared available. After 10 days a leak on a local flowmeter was discovered.


Six month after discovering cracking in reactor vessel head penetrations at Tihange-1, Electrabel has decided to order a replacement vessel head from Framatome, but the unit´s safety to operate while awaiting the replacement has not yet been accepted by regulators.
The entire replacement job, which is estimated to cost 300-million Belgian francs (about U.S.$8-million) including the replacement head.
Framatome had offered to adapt one of the vessel heads under construction at Chalons for EDF to the slightly different design of Tihange-1. EDF is past the midpoint of a vast campaign, begun in 1993, to replace the vessel heads on all its PWRs.
The most worrisome crack, from the view of safety authorities, is an axial throughwall crack described as "relatively long" and situated within the vessel head, just below the weld between the vessel head and the penetration.


Explosion with subsequent fire in non-nuclear island: 4 workers injured, one of these died in hospital.


Sudden leak through an axial crack of 30-40 t/h: Shutdown before safety injection was actuated; Damage was caused by a loose part between the support plates. The location is practically inaccessable. 59 tubes were plugged in the affected zone.
Restart on August 1. Two weeks later ( August 13) there was a new leak in the same SG ( 10 lit/h)


Completion of 20th-year outage:
Plant will be safer & more efficient (90 MW added ) at a cost of US$ 230 million The new SG came from MHI, its the first time Japanese SG are working outside their home.
Outage is one of the biggest ever in a NPP: since beguinning of June 1400 people have been working on the decennial inspection programm (RPV & vessel internals, pipes, pumps & valves) as well as installing a variety of new equipment including low pressure rotors for both turbines, pressurizer heaters and relays for the RPS. It consumed more than 600.000 hours of on-site work.


Judge has ordered to stop building a spent fuel sorage pool, ruling in favor of the major of the nearby town Huy. Construction was stopped because because actual building differs from original plans. The town's major also argued that Electrabel had violated procedure by not conducting a regional EIA.
The pool would double the storage capacity and is supposed to enter operation in 1997.
In August an appeals court overruled the jugde's order from May.


Tihange-3 like Doel-4 a 1000 MW Westinghouse-design PWR has suffered extensive SG tube cracking and is operating with circumferential tube cracks.
SG replacement is planned for mid 1997 and will be done by Westinghouse. The three new SG will be manufactured by Framatome.


Unit is being loaded with MOX fuel. It is the first time MOX is used in a reactor in Belgium. MOX will be burnt only in Tihange 2 and 3 because Belgium is reprocessing only part of its fuel.


Fire in an electric panel feeding ventilation without safety function.


Unit restarted Sept. 19 after an outage, was brought to full power by Sept. 23. During the process of reactor stabilization, measurments of power level differed by more than 2%. This disparity should have led to recalibration of instrumentation within 24 hours, but it took 2 days


Shutdown because of a leaking PRZ spray valve.