Reclamation of Pit 7.1
Pit 7.1 of Rotondella ITREC Plant was designed and built at the end of the Sixties according to national laws and international standard of that time.
This underground structure enables the disposal of the radioactive solid high-level waste resulting from fuel reprocessing activities.
It is a vertical prism-shaped structure weighing 130 tonnes and with a volume of 54 cubic metres, located at a depth of 6.5 metres and today called “monolith”.
The radioactive waste in the structure is stored in 220-litres oil tanks, enclosed in cementitious mortar, and located within four square-section wells.
In 2007, a hydraulic defence system was implemented to ensure maximum safety conditions for the reclamation works of Pit 7.1; for these works, Sogin developed an unprecedented complex prototype engineering prototype solution.
Remediation works started in 2012 with the launch of civil works, the construction of a shed to confine the working site from external environment, and the installation and testing of service facilities.
To ensure maximum safety in each stage of the reclamation, a structure to cover the working site of Pit 7.1 was completed in 2013; moreover, ventilation, fireproofing and electrical systems have been installed along with a radiological monitoring systems and a portal for the control of extracted soil and excavation tools around the monolith.
In 2014, after the implementation of stabilisation, drainage and protection systems for the palisade, excavation works, and structure assessment of the monolith were initiated; the analysis detected a small leaching of aqueous liquid from a wall of the monolith which affected a limited portion of soil (approx. 2 square metres).
Sogin has implemented security measures and carried out the leachate sealing by promptly implementing a sampling collection of leachate and soil.
The radioactivity levels and the radioprotection assessments excluded any impact on environment, people and workers.
Works continued with the drainage of approx. 800 litres of liquid found in the monolith.
Before starting the cutting operations, further stabilisation systems have been adopted for the monolith; the cutting operations will be carried out in a confined space.
In March 2019 work began on cutting the monolith in a confined space. Sogin proceeded first with a horizontal cut, - with the perforation of the structure basis through a core drilling
machine with disposable drills. These activities were completed in May 2019.
Subsequently, the structure was cut vertically with a diamond wire from top to bottom, separating the four wells from one another. The activity ended in September 2019.
Subsequently, the individual wells were encapsulated to proceed with their lifting and extraction, and then be transferred in maximum safety within a temporary storage site.
During an inspection carried out inside warehouse 9.3 following the positioning of the P2 well (third well extracted), drops of liquid were detected on the floor, an eventuality expected and assessed in the project phase.
Sogin promptly notified the event to the ISIN supervisory authority which, during a specific inspection, took note of the exiguity of the spill, which had no radiological consequences for the population and the environment. During the inspection, environmental samples were acquired for independent radiometric determinations that were carried out by ARPA Basilicata, which confirmed the absence of radiological consequences for the population and the environment as the measured values are lower than the reference levels indicated by the Supervisory Body.
The removal of the pit 7.1 monolith ended on 18 December 2019, with the extraction of the last well.