Consultation on the variation application for permit XB3539DH to increase the C-14 gaseous discharge limit at Sizewell B nuclear power station

Closed 1 Oct 2020

Opened 19 Aug 2020

Feedback updated 13 Sep 2021

We asked

We consulted on the application to vary the radioactive substances environmental permit for Sizewell B Power Station from 19 August 2020 to 1 October 2020. It provided the opportunity for the public, professional bodies and other stakeholders to provide comments on the application.

You said

We received 16 responses to the consultation from various stakeholders. The responses included various comments and questions which have been summarised in the decision document (found below under ‘Files’).

We did

We assessed the application and the consultation responses were considered as part of determining the application. We issued the permit variation on 1 September 2021. The key changes to the permit are:

  • a change the annual limit and quarterly Notification Level for carbon-14 disposals to air;
  • Condition 2.3.3 (c) relating to on-site incineration has been removed;
  • an information requirement has been added (IC5) which requires the Operator to carry out chemical analysis of the gas released from the gaseous radioactive waste system to determine the relative amounts of methane and carbon dioxide that is discharged and report the results;
  • Table S3.4 has been amended to reflect changes to legislation relating to the trans-frontier shipment of radioactive waste and spent fuel.

Results updated 13 Sep 2021

Please find below the published Decision Document (DD) which describes our findings on the consultation and the action we took.



This consultation will enable us to collect stakeholder views on the application made by EDF Energy Nuclear Generation Limited to vary the Environmental Permit for the disposal of radioactive waste from Sizewell B Power Station. It is separate from the application made by another company in the EDF group for Environmental Permits at the proposed Sizewell C Power Station.

Operation of Sizewell B Power Station routinely creates radioactive waste that needs to be disposed of. Discharges of radioactive waste to the environment are regulated by an Environmental Permit which specifies certain limitations and conditions.

Operation of the pressurised water reactor at Sizewell gives rise to the radionuclide carbon-14; most of this waste is discharged in gaseous form to air where the environmental impact is less than if it were disposed of to sea. 

EDF has applied to increase the limit for carbon-14 discharges to air from 500 gigabecquerels (GBq) to 600 GBq in any twelve-month period.

When the reactor started operating in 1995, carbon-14 discharges to air were limited to 600 GBq over 12 months. This limit was based on the predicted rate of creation of carbon-14 in the original design of the reactor systems.  In 2007 we reduced that limit to 500 GBq over 12 months when we reviewed the Permit.  That new limit was based on actual emissions data after ten years of operation.

Longer periods of electricity generation has meant that carbon-14 emissions to air have increased since then. Improvements to the reliability of the radioactive waste system has meant that more carbon-14 is extracted for discharge to air rather than sea. In addition, carbon-14 emissions tend to increase over the course of the station's 18-month fuel cycle. Discharges of carbon-14 are not generally designed to be abated but may be delayed within the plant and released at a slower or faster rate throughout the fuel cycle.

Taken together, this means that EDF could exceed the current annual limit for emissions of carbon-14 to air.    

EDF has therefore applied to increase the limit for carbon-14 emissions to air back to the original value of 600 gigabecquerels a year.  The applicant has submitted information to demonstrate that this represents Best Available Techniques and a radiological impact assessment based on the proposed limit. The impact assessment predicts that the change in dose to public resulting from the proposed change to the Permit limit will not exceed 0.01 microsievert per year. This is a dose increase of less than 0.1% compared to that arising from the current permitted limits.

We will determine whether EDF is applying Best Available Techniques in respect of carbon-14 emissions to air and whether the radiological impact of the proposed increase is within prescribed dose limits and constraints.


Why your views matter

We will take consultation responses into consideration as part of our determination of the application for EDF's Environmental Permit variation at Sizewell B.  If we decide to grant the application we will explain how we made our decision and how we have addressed the comments that were raised.

We will only vary the permit if we believe that harm to the environment, people and wildlife will be minimised. If the applicant can demonstrate that the varied permit will meet all of the legal requirements, including those for the use of best available techniques, public radiation dose and wildlife radiation dose, then we are legally obliged to grant the application.

Advice about what aspects and issues we can and cannot take account of is provided below.

We can take account of:

  • relevant environmental regulatory requirements and technical standards.
  • information on local population habits and practices and sensitive sites.
  • comments on whether the right process is being used for the activity, for example whether the technology is the right one.
  • the potential impact, whether the impact is acceptable and what pollution control measures or abatement may be required.
  • information that we have not been made aware of in the application.

We cannot take account of:

  • issues beyond those in the relevant environmental regulations.
  • anything outside the scope of the Environmental Permitting Regulations.
  • whether a site should have a formal designation under Habitats Directive or other conservation legislation.
  • whether the activity should be allowed or not as a matter of principle and the Justification of practices involving radiation. For example, we will not consider whether nuclear power generation is an appropriate process or whether alternative methods of generating electricity should be used instead.
  • land use issues, or sustainability challenges.
  • the impact of traffic travelling to and from the site.
  • comments about the Government’s energy policy.
  • comments about the transport of radioactive waste.


  • Businesses
  • Charities
  • Statutory organisations
  • Members of the public
  • Elected representatives, including MPs
  • Local councils
  • The nuclear industry


  • Permits
  • Nuclear