SPENT FUEL POOL EMPTYING, DRAINAGE AND PURGING
AT EUREX Plant (Italy)
By Costantino BIONDANI (email@example.com);
Michele GILI (firstname.lastname@example.org);
Mara MOLLO (email@example.com)– Sogin
Sogin EUREX Site, str. Crescentino I-13040 SALUGGIA
At the beginning of 2004, some leakages from the spent fuel pool
(SFP), a 675 m3 concrete basin, were discovered at the EUREX
(Enriched Uranium Extraction) pilot reprocessing plant, which
was in operation between 1970 and 1983.
Thin cracks in the pool wall caused leakages through the annular
space of the pool and from there into the ground. Environmental
analyses and radiological measures revealed the limited presence
of Sr-90 radionuclide in upper water table samples.
In 2006, Sogin started not only transferring fuel to the nearby
Avogadro Fuel Repository, but also draining and purging the
The main steps of involved in
this process are described as follows:
STEP 1: TRANSFER OF THE FUEL TO THE AVOGADRO
Irradiated fuel (a total of 2 tonnes) from the
Trino PWR, the Garigliano, according to the following strategy:
Reusing an AGN-1 transport cask with an internal
basket modification (6 elements for each cask; a total of
10 fuel transfers)
Loading the cask outside the water, designing a shielded shuttle
to move the fuel from the pool to the cask
Transferring the fuel to the nearby Avogadro Fuel Repository,
a short distance away (less than 1 km) reduced transport
Fuel elements in SFP
Duration: May-July 2007
STEP 2: RESTORATION OF WORKING AREAS
The maintenance of conventional and radiological safety was
achieved by performing the following activities:
The removal of 300 tonnes crane used for materials handling
The transfer of AGN-1 cask and accessories from Trino NPP
The restoration of grates and rails from SFP Area
The removal of absorption frames used for moving cask AGN-1.
AGN-1 cask loading on trailer
Duration: July 2007
STEP 3: REMOVAL FROM THE SFP OF SLIGHTLY CONTAMINATED DEVICES
This activity regards the removal of slightly contaminated devices,
but not radiating, as for example:
• metallic 'clovers' not removed
the previous year
quivers containing Trino NPP elements and small baskets
various devices used in the pool (rods, lamps, television camera)
foot bridges used for quivers handling during loading fuel
Extraction of metallic 'clovers'
All the activities were performed according to
operative procedures for fuel handling and radiation protection.
In particular, the phases involved in managing the waste were:
the washing of waste in SFP Area
the removal of waste from SFP Area
the allocation of waste into appropriate containers
the transfer to waste to the waste treatment company
Duration: September-November 2007
STEP 4: REMOVAL FROM THE SFP OF THE RADIATING
This activity was the most relevant because it
concerned the removal from the SFP of radiating components, such
as the headstock MTR (Material Testing Reactors) elements and the
An Operational Plan was written for the Italian Safety Authority
and appropriate shielding and handling frames were designed in
order to respect all the laws and regulations for transport and
Shielded containers for activated Headstock MTR
Duration: December 2007; 1 week.
STEP 5: PRELIMINARY CLEANING ACTIVITIES OF SFP
These activities were performed by NUKEM Technology
GmbH and ENERGY SOLUTIONS and consisted of the following phases
of operational cleaning:
the extraction of various devices from the pool and
radiological cleaning and packaging
the sucking out of waste and sludge from the pool
sediment materials recovery from the bottom and the
walls of the pool
Duration: November 2007- February 2008; 2 months.
STEP 6: DISMANTLING OF PLANT COMPONENTS
This step consisted of removing and cleaning of plant components
and frames that require special disassembly, for example the safety
hydraulic System (SIS), the SFP bottom grids, pipes and metallic
Duration: March 2008: 2 weeks.
STEP 7: SFP WATER PURIFICATION
The purification of the SFP water was performed by two different
The Wall & Floor WasherTM technique,
by NUKEM/ Energy Solutionsn, an outsourced service
cleaning system was used to remove contaminated
sludge from the EUREX SFP bottom: about 50 GBq of
fission products and
transuranic sludge were recovered.
The Electrocoagulation process, called the SAFETM SYSTEM, by Energy Solutions, an outsourced service
The water treatment was performed using ElectroCoagulation
coupled with ultra-filtration and final polishing with
ionic exchange resins.
Water flow gets through the cells of the system and three
chemical processes occur: coagulation, oxidation and aeration.
Inside the ElectroCoagulation Unit (container ISO 20’)
there are components for water treatment (settling, sludge
and feed tanks)
that allow the separation of the sludge from the water.
Internal Layout EC System
March – June 2008: 4 months.
STEP 8: SFP WATER DRAINAGE AND DOWNLOAD
After accurate radiological monitoring (more than one hundred
samples were analysed), water was gradually drained and transferred
from the pool to the waste pond (a 1000 m3 external basin).
Surface radiological contamination was limited to pool
walls by using specialised painting.
The final water downloading into the nearby Dora river
required prior documentation presented to the Italian
in order to justify the release levels.
Duration: June 2008: 1 month
Additional steps are scheduled for the following activities:
A SURVEY OF THE CONTAMINATION LEVEL OF THE ANNULAR
Radiological characterisation of the annular space, pool
frames and ground below the pool will be carried out
THE CONDITIONING AND TREATMENT OF WASTE ACTIVITIES
An outsourced service for the conditioning and treatment
of waste, in particular sludge and resins, will be used.