NucNet News No. 147
Final INES Level Three Rating For Paks Unit

Inspections at unit two of Hungary’s Paks nuclear power plant have identified
leakage in fuel assemblies inside a cleaning system, during the unit’s annual
refuelling outage, as the source of a discharge of radioactive gases earlier this
month.

The incident (see News No. 145, 14th April), provisionally registered as level
two on the International Nuclear Event Scale (INES), has now been given a final
INES rating of level three. The INES description of the event said: “As a result
of conducted technical actions, the releases were reduced below the authorised
limit.”
A joint statement issued by the Hungarian Atomic Energy Authority (HAEA) and
Governmental Co-ordination Committee said the covering lid of the cleaning
vessel was lifted on 16th April and a video camera was inserted. According to the
images “the condition of the assemblies was significantly worse than expected,
most of the assemblies (if not all) are deformed (and) claddings are opened.”
However, the statement added: “There is no increase in the atmospheric emissions
and a co-ordinated programme for environmental measurements has started. There is
no detectable increase in population doses. At this moment, there is no need for
the introduction of any countermeasures.”

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NucNet News No. 145
Provisional INES Level Two Rating For Paks

An investigation is under way at unit two of Hungary’s Paks nuclear plant after
monitoring systems detected a discharge of radioactive gases during a periodic
maintenance outage.

The 10th April incident has been provisionally rated as level two on the
International Nuclear Event Scale (INES). A report by the plant said there was a
controlled release of gases, although the “amount and activity of the discharged
gases were insufficient to cause any change in the normal readings of the
environment monitoring system within and outside the area of the plant”.
Initial results show that the discharge may have originated from a cleaning
system installed at the reactor, and refer to a “low-rate leaking” of one of the
30 fuel assemblies loaded into the system for cleaning. The cleaning system is
now being inspected and will be followed by inspection of the individual fuel
assemblies concerned. The other three units at the plant continue to operate as
normal.

Zdroj: NucNet