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Staff Responses to Frequently Asked Questions Concerning Decommissioning of Nuclear Power Reactors

1. General 8. License Termination And the Ultimate Disposition of the Facility
2. Decommissioning Process 9. Hazards Associated with Decommissioning
3. Decommissioned Sites 10. Finances
4. NRC Activities 11. Socio-economic Issues
5. Spent Fuel 12. Public Involvement
6. Radioactive Low-Level Waste 13. Getting Additional Information
7. Transportation 14. Bibliography

9.   Hazards Associated with Decommissioning

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9.1. Workers
9.1.1. Where do the decommissioning workers come from ?
9.1.2. Is worker safety considered in the planning for and review of decommissioning ?
9.1.3. How much occupational dose is received by workers during decommissioning ?
9.1.4. Are there limits on the amount of occupational dose that may be received ?
9.1.5. Does the licensee have to estimate the occupational dose before the decommissioning process is initiated ?
9.2. Public and Environment
9.2.1. Is the safety of the public considered in the planning for and review of decommissioning ?
9.2.2. How much dose will the public receive during the decommissioning process ?
9.2.3. Who estimates what the doses are, and how are these estimates made ?
9.2.6. Will there be continued environmental monitoring of the site and the offsite areas to measure releases of radioactive material during the decommissioning process ?
9.2.7. Who will perform the environmental monitoring ?
9.2.11. What types of accidents at the reactor site are considered and what would be the consequences to the public ?
9.3. General
9.3.1. In general, how safe is a decommissioning plant in contrast to an operating plant ?
9.3.2. Will there still be emergency preparedness plans and warning sirens in the vicinity of the plant ?
9.3.3. What measures are taken to prevent vandalism and sabotage during decommissioning ?

9.1.  Workers
  9.1.1.  Where do the decommissioning workers come from ?
The majority of workers for an immediate decontamination and dismantling programme will likely be people who worked on the operating plant. These workers are most familiar with the facility and its history.
Some jobs, however, may be contracted out to companies that have gained experience at other plants in specialized areas of decommissioning or dismantling.
There will be very few employees during the storage phase in facilities that are placed in a storage mode.
A new group of workers will likely need to be hired who are most likely unfamiliar with the plant, but who will probably have had some decommissioning experience at other facilities.
  9.1.2.  Is worker safety considered in the planning for and review of decommissioning ?
Yes. Worker safety is considered both in terms of the radiological hazard (their exposure to radiation) and in terms of industrial safety.
  9.1.3.  How much occupational dose is received by workers during decommissioning ?
The amount of occupational dose received during the decommissioning process will depend on the design and size of the facility as well as on the plans for decommissioning.
A greater amount of occupational dose is anticipated to be incurred for an immediate decontamination and dismantling than for a storage period followed by dismantling.
The person-rem numbers are the doses that are received by all the workers.
  9.1.4.  Are there limits on the amount of occupational dose that may be received ?
Yes. The regulations state that the licensee shall control the occupational dose to individual adults to an annual limit, depending on the regulation in the country, -- total effective dose equivalent to the entire body -- or to an organ dose.
There are also dose limits to the eyes, the skin, and the extremities.
  9.1.5.  Does the licensee have to estimate the occupational dose before the decommissioning process is initiated ?
No. However, at the time that the license-termination plan is updated, the licensee is required to update its environmental report as appropriate to reflect any new information or significant environmental change associated with the applicant's proposed decommissioning activities.
The environmental report contains an estimate of occupational dose, so the licensee needs to estimate the occupational dose for decommissioning to determine if the estimates are within the range given in the environmental report for routine operations.
However, it becomes also a challenge to perform "decommissioning strategies" leading to the lowest dose uptake by workers, based on one hand on the history of the plant and on the other hand mostly on the experience gained by "decommissioners", following the so-called "Alara Principle".
9.2.  Public and Environment
  9.2.1.  Is the safety of the public considered in the planning for and review of decommissioning ?
Yes. The safety of the public is a major concern, even though the potential for hazards to the public from the decommissioning process and potential accidents is much less than it is when the facility is operating.
  9.2.2.  How much dose will the public receive during the decommissioning process ?
The major source of exposure to the public is from the shipment of low-level waste from the reactor site to the low-level waste disposal site.
The radiation dose is received by people who travel along the same route as the trucks that are transporting low-level waste if not on a private way.
However, because of the variability in the timing of each shipment, the short period of time that any person would be near any of the trucks, and the small dose that is allowed 6 feet from the side of a truck, the dose that is received by any one person traveling down the highway or stopped at a rest stop is a very small fraction of the annual dose that the person would receive from background radiation.
Minor sources of exposure to the public include radioactive effluent releases during the decommissioning process as discussed in the response to "Question 9.2.4.".
  9.2.3.  Who estimates what the doses are, and how are these estimates made ?
The licensee estimates the doses.
The doses are estimated using assumptions about the amount of radioactive material that will be released or the proximity of the public to the source of radiation.
The doses are calculated using approved scenarios, assumptions, parameter values, and conceptual models. The regulator reviews the licensee's estimates of the doses and often recalculates the doses using its own assumptions for activities with the potential for significant worker exposure.
  9.2.6.  Will there be continued environmental monitoring of the site and the offsite areas to measure releases of radioactive material during the decommissioning process ?
Yes. The radiological environmental monitoring programme that was in place at the nuclear plant will continue even after the plant is shut down.
The programme will be modified to appropriately monitor the types of releases that may occur during decommissioning and to monitor results at appropriate intervals of time. Not all measurements will be made on a continuous basis.
The licensee uses the results of the environmental monitoring programme to calculate the dose to the public.
  9.2.7.  Who will perform the environmental monitoring ?
The Radiological Environmental Monitoring Programme is conducted by the licensee. The procedures and results of the Radiological Environmental Monitoring Programme are inspected and reviewed by the regulator to ensure that all requirements are being met.
  9.2.11.  What types of accidents at the reactor site are considered and what would be the consequences to the public ?
Once the reactor permanently shuts down, the risk to the public is greatly reduced; however, there are still several accidents that may occur with consequences offsite.
The accidents that have the potential for the greatest offsite doses are those that involve the spent fuel that has recently been moved from the reactor to the spent fuel pool. Over time, the hazard from the spent fuel diminishes as the radioactive material in the fuel decays.
Licensees are required to examine their sites and decommissioning plans to identify postulated accidents that could occur during decommissioning. An analysis of these accidents is required in their "Final Safety Analysis Report", which is part of the licensing basis for the plant.
Except for the fuel-related accidents in the first year(s) after the facility ceases operation, the offsite consequences of these accidents are very small and do not require offsite emergency response.
Examples of the types of accidents that are considered by the licensees include :
  •   Cask or heavy load-handling accident with a subsequent drop into spent fuel pool
  •   Loss of cooling for the spent fuel pool or loss of water from the spent fuel pool
  •   Materials handling event (non-fuel)
  •   Radioactive liquid waste releases
  •   Accidents from handling spent resin
  •   Fire
  •   Explosions
  •   "External events"
  •   Transportation accidents.
If a licensee requests an exemption to a regulation because they believe it no longer applies due to the decommissioning state of the plant, they must show that the regulation is not needed including consideration of the risk to the public.
Additional information regarding the consequences of spent fuel pool accidents is given in the response to "Question 5.8.4.".
9.3.  General
  9.3.1.  In general, how safe is a decommissioning plant in contrast to an operating plant ?
At the time that the plant permanently ceases operations and the fuel is removed from the reactor, the risk to the public from an accident drops significantly.
  9.3.2.  Will there still be emergency preparedness plans and warning sirens in the vicinity of the plant ?
For some period of time after the licensee ceases reactor operations, the offsite emergency preparedness planning will be maintained.
This period of time depends on when the reactor was last critical as well as onsite-specific considerations. Offsite emergency planning may be eliminated when the fuel has been removed from the reactor and placed in the spent fuel pool, and sufficient time has elapsed, and there are no longer any postulated accidents that would result in offsite dose consequences that are large enough to require offsite emergency planning.
There would be no requirement to maintain offsite systems to warn the public. Onsite emergency plans will be required for both the spent fuel pool and the Independent Spent Fuel Storage Installations, but offsite plans will not be required.
If, however, an operating plant is located at the same site as the decommissioning plant, the emergency preparedness plans will still be in effect for the operating plant.
  9.3.3.  What measures are taken to prevent vandalism and sabotage during decommissioning ?
The facility is required to have a security plan when a plant is being decommissioned; however, as the hazards are removed from the nuclear reactor site, security requirements are modified.
Many plants reduce the area that they keep very secured to the area around where the spent fuel is stored. This is known as the "nuclear island".
Reducing the size of the area that has strict security measures allows for better control of the material that must be safeguarded. Security measures for the nuclear island are designed to prevent sabotage or removal of the nuclear material.

10.   Finances

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In order to avoid any kind of misunderdstanding, this topic will be treated more in detail, following if possible the FAQ's, when the "right information" will be got from each involved company/institution/country.
Anyway, in any case, the total cost of decommissioning depends on many factors, including the sequence and timing of the various stages of the program, location of the facility, current radioactive waste burial costs, and plans for spent fuel storage.
The costs are adjusted annually, as further specified in the regulations. Actual site-specific costs incurred and estimated costs of decommissioning give a better indication of what the process costs.
Decommissioning costs vary, based on plant size and design, local labor and radiological waste burial costs, and the specific process that is being used for decommissioning.
The licensee makes the site specific estimates of the decommissioning costs or hires a contractor who has extensive experience in making these estimates.
An estimate is made at or about 5 years preceeding the projected end of operations. At this time, power reactor licensees shall submit a preliminary decommissioning cost estimate, which includes an up-to-date assessment of the major factors that could affect the cost to decommission.
If the amount of money available is inadequate, the licensee has approximately 5 years to adjust the money in the decommissioning trust fund to ensure that appropriate funds are available for decommissioning.

11.   Socio-economic Issues

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11.1. What impact would each of the alternatives have on the economy of the surrounding area, including work-force requirements ?
11.2. How many people are needed onsite during the decommissioning process ?
Is this more than during operations ?

11.1.  What impact would each of the alternatives have on the economy of the surrounding area, including work-force requirements ?
The biggest socio-economic impact occurs before decommissioning starts, at the time the plant ceases operations, and the tax income created by the plant is substantially reduced.
The surrounding communities may find their property tax base reduced in half or more, depending on the presence or absence of other industries in the area : it is the biggest "economic impact".
Typically, additional public services are not required during decommissioning because the plant staff will be smaller than the operating staff : it is the biggest "social impact".
11.2.  How many people are needed onsite during the decommissioning process ?
Is this more than during operations ?
After cessation of operations, the number of workers in the plant will be reduced.
Plants that are currently being decommissioned using the "DECON" alternative have work forces in the range of approximately one-third to one-tenth the number of persons who were employed at the plant during its operation.
These personnel are periodically supplemented with contract personnel during major decommissioning activities, such as the removal of large components like the steam generators and pressurizer.
If the plant were placed in "SAFSTOR", the number of workers would be further reduced. Decommissioning plants that are located at the same site as operating facilities generally have a staff of 20 or fewer during SAFSTOR. Single-unit plants (not located next to operating units) require a larger staff and may have 20 to 70 employees during SAFSTOR. After the SAFSTOR period, the number of workers would increase to the range of one-third to one-tenth the number of persons who were employed at the plant during its operation, and would be further supplemented with contractor personnel for the final cleanup of the site.

12.   Public Involvement

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The following section has to be checked with people involved in this field.

13.   Getting Additional Information

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The following section has to be checked with people involved in this field.
NRC's website contains information of interest to the public (http://www.nrc.gov). This site also has a link to the "Public Electronic Reading Room". Copies can also be read online or downloaded electronically from the NRC's website.

14.   Bibliography

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See "original F.A.Qs" from the NRC.

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