Some Realities of Nuclear Power Plant Decommissioning by L. Lanni Nuclear power plants, like all other structures, wear out or must for other reasons be removed or replaced Taking a nuclear facility out of service is generally termed "decommissioning", an operation which can be described in more detail as the measures taken at the end of the facility's operating lifetime to assure the continued protection of the public from residual radioactivity and to deal with other potential safety concerns associated with the retired facility. This can be done in several ways, however the IAEA currently has defined three basic options 1 fo r decommissioning a nuclear reactor Option 1 : Lock-up with surveillance The reactor is left essentially intact but in a safe state. All fuel and heat transport fluids are removed Surveillance, maintenance and monitoring continues This is regarded as a temporary option prior to further work, but it provides safety for the public and the environment at low initial cost It allows time for decay of radioactivity and defers making irrevocable decisions regarding future plant disposition, but it does not make the site available for other uses. Option 2: Restricted site release The reactor is significantly decontaminated and remaining areas with important residual radioactivity levels are sealed. Fuel and heat transport fluids are removed from the reactor, radioactive components that can be easily dismantled are removed, other components that could constitute a radiological hazard during the planned timespan of this decommissioning optio n are al so removed Various con tainment items generally rem ain, and are augm ented where ne cessary Some surveillance and monitoring are maintained Par ts of the facility or site may be available for other uses, but restrictions prevent the penetration of the containment barriers This option provides radiological safety and alternative use of part of the site, but does not allow complete freedom in future use or development. Option 3: Unrestricted site release All radioactively contaminated reactor structures are dismantled and all radioactivity above acceptable levels is removed No inspection, surveillance or monitoring is required on completion of this option and the site may be released for other purposes without restriction These options are termed "stages" in Ref [ 1 ) Until his return to the United States in September 1978 , Mr Lanni was in the Waste Management Section, Division of Nuclear Safety and Environmental Protection, IAEA 24 IAEA BULLETIN-VOL 20, NO 6
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Nuclear power plants, like all other structures, wear out or must for other reasons be
removed or replaced
Taking a nuclear fac ility ou t of service is generally termed "d ecom mission ing", an operation
which can be described in more detail as the measures taken at the end of the facility's
operating lifetime to assure the continued protection of the public from residual radioactivity
and to deal with other poten tial safety concerns associated wi th the retired fa cil ity . This canbe done in several ways, however the IAEA currently has defined three basic options 1 fo r
decommissioning a nuclear reactor
Option 1 : Lock-up with surveillance
The reactor is left essen tially in tact bu t in a safe state. A ll fu el and heat transpo rt fluid s
are removed Surveillance, maintenance and monit or ing con tinues This is regarded as a
temporary option prior to further work, but it provides safety for the public and the
environm ent at low initia l cost It allows time fo r decay of radio activity and defers making
irrevocable decisions regarding future plant disposition, but it does not make the siteavailable for other uses.
Option 2: Restricted site release
The reactor is significantly decontaminated and remaining areas with important residual
radioactivity levels are sealed. Fuel and heat transport fluids are removed from the reactor,
radioactive compone nts tha t can be easily dismantled are removed, other com pone nts tha t
could constitute a radiological hazard during the planned timespan of this decommissioning
op tion are also removed Various con tainmen t items generally rem ain, and are augmented
where necessary Some surveillance and m on ito rin g are ma intained Parts of the fac ili ty orsite may be available for other uses, but restrictions prevent the penetration of the
conta inme nt barriers This op tion provides radiological safety and alternative use of p art of
the site, but does not allow complete freedom in future use or development.
Option 3 : Unrestricted site release
All radioactively contaminated reactor structures are dismantled and all radioactivity above
acceptable levels is removed No insp ectio n, surveillance or mon ito rin g is requ ired on
com pletio n of this optio n and the site may be released for other purposes w ith ou t restriction
These opt ions are termed "stages" in Ref [ 1 )
Unt i l h is return to the Unite d States in Septem ber 19 78 , Mr Lanni was in the Waste Man agem ent Sec tion,
Div is ion o f Nuc lear Safety and Environmental Protection, IAEA
[1 ] BA INB RID G E, G R , et al , Decommissioning of Nuclear Facilities A Review of Status, Ato m icEnergy Review, 12 1 (1974) 14 6- 60
12] INT ER NA TIO NA L ATO MIC ENERGY A GEN CY, Decommissioning of Nuclear Facili ties,Report of a technical meeting, IAE A-1 79 , Vienna (October 1975)
[3 | LU NN IN G , W H , "Decomm issioning of Nuclear Facilities", IAE A-C N-3 6/7 1, (Proc Int Conf onNuclear Power and its Fuel Cycle, Salzburg, 2 - 1 3 May 1 97 7) 4, IA EA , Vienna (1977) 7 95 -8 0 6
[4 ] CR EG UT , A , "L e declassement des installations nuc leates ", Revue Generale Nu cleaire, 3 (1978)166 -72
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