Page 171 - Beyond Decommissioning

152 Beyond Decommissioning

Operation at full power (50 thermal MW) and full temperature was achieved in 1965.
BONUS was permanently shut down in 1968 because of technical difficulties and the
high cost of the needed refurbishment.
The operator decommissioned the reactor between 1969 and 1970. All nuclear fuel
and some highly activated components were removed, the piping was flushed, the reac-
tor vessel and all components inside the biological shield were entombed in concrete
and grout, and the systems external to the entombment were decontaminated. Many
other contaminated and activated materials were placed within the entombment struc-
ture. General decontamination to unrestricted use was carried out in all accessible
areas. The BONUS reactor dome was repainted in 2014.
Beginning in 2019, DOE Legacy Management (LM) will perform inspections of
the site every other year. Visual inspections are performed to evaluate the structural
functions of the buildings and entombment structure and the conditions of the areas
open to the public. Moreover, LM will maintain site records regarding the design, con-
struction, operation, decommissioning, and postdecommissioning monitoring of the
BONUS structures. A museum on the main floor of the BONUS building is open
to the public, including displays about the site history and the development of nuclear
energy.
Everything inside the reactor building has been remodeled to give the impres-
sion of an operating reactor. A computer learning room with 12 computers stations
has been installed in the former Health Physics Office. DOE produced an environ-
mental assessment in 2003, which indicated that no unacceptable risk to human
health or the environment was induced by the use of the main floor as a museum
(DOE, 2018).

6.2.1.2 Fort St Vrain and SM-1A NPPs, USA

Construction of Fort St. Vrain (FSV) NPP commenced in 1968. It was the first gas-
cooled reactor in the USA, a model that was later abandoned. The first commercial
power was distributed to the electric grid in July 1979. The plant had a generation
capacity of 330 MWe.
Commercially, the plant was a failure. Being a prototype, it was subject to a number
of technical issues that took time and money to fix. Eventually, after a last incident, the
plant was prematurely shutdown in August 1989. The operator’s initial task was to
find a storage location for the spent fuel. The operator had a contract with the USDOE
to ship FSV spent fuel to the Idaho National Engineering Laboratory (INEL), and all
previously removed spent fuel had been shipped there. However, Idaho legally
blocked further spent fuel shipments to INEL, and the operator built an onsite inde-
pendent spent fuel storage installation (ISFSI). By June 1992, all reactor spent fuel had
been transferred to the ISFSI. Later on the DOE accepted to take title to the spent fuel,
including reimbursement of ISFSI construction and maintenance expenses to the oper-
ator. The ISFSI license was transferred to DOE in June 1999.
The decommissioning strategy involved flooding the Prestressed Concrete Reactor
Vessel to provide shielding and contamination control: divers were extensively