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Decommissioning Nuclear Reactors. Background. Before a company decides to close it’s power reactors the facility must be put in to a state that no longer has a residual radioactive level, clean up of all radioactive contaminated systems and structures, and remove the radioactive fuel.
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Background Before a company decides to close it’s power reactors the facility must be put in to a state that no longer has a residual radioactive level, clean up of all radioactive contaminated systems and structures, and remove the radioactive fuel.
Why Decommissioned? Why are power plants decommissioned? Since most power plants can only operate from around 40-60 years now-a-days these plants are required by the NRC to decommission after power operations cease. This policy was enacted based on the idea that it is necessary to reduce the amount of radioactive material at the nuclear site and protect the environment. So if the nuclear site is no longer running all the radio active material should be removed immediately by one of the 3 decommissioning processes.
Continued. Decommissioning’s main purpose is the safe return of the facility to a condition in which it poses NO threat to the public health and safety of the environment around. The main reason for required decommissioning is to remove the potential hazard for these facilities to degrade if left abandoned in to potential health hazards.
When to decommission? • Most nuclear power plants are designed to last for about 30 years. (Newer plants are designed to last for about 40-60 years.) • Companies have been attempting to have longer operating periods in order to help balance the amount of money required to make the plants with the amount of money made while operating.
Decommissioning Strategies • There are three main strategies to decommission a nuclear facility. DECON (Immediate Dismantling), SAFSTOR (Safe Enclosure), and Entombment. • The first, being the fastest, is known as DECON (Dismantling). This is the immediate dismantlement of the facility and all parts of said facility are decontaminated to a safe level.
Safe Storage • The second type is SAFSTOR, it takes longer than DECON and in this a nuclear facility is monitored until the radioactivity decreases to a level that allows the facility to be dismantled without decontamination requirements • Essentially storing the materials until deemed safe enough for removal.
Entombing • The final type is ENTOMB. • As the word suggests, this is where the structure becomes permanently encased by a material that would prevent the leaking of radioactive materials. • Usually involves reducing the size of the area the radioactive material is taking and encasing the entire structure to a degree that it will ensure the radioactivity is longer a concern.
How is a power plant decommissioned? • Decommissioning involves physically removing the spent fuel source from the reactor vessel, dismantling any parts that contain activation products. Cleaning any potentially radioactive materials in the facility. • The decision between decontaminating the components or simply shipping them off to a waste processing facility is based mainly on the licensee’s opinion of cost difference between the two.
Final Result? • After decommissioning a reactor there should be no danger of a radioactive accident occurring to anyone going anywhere on the property. Essentially the entire site is put under a radioactive ‘clean-up’ and decommissioning is not entirely complete until the plot land is deemed harmless.
References • http://www.nrc.gov/reading-rm/doc-collections/fact-sheets/decommissioning.html • http://www.nrc.gov/about-nrc/regulatory/decommissioning/faq.html#2
