Office for Nuclear Regulation

Sizewell C Nuclear Site Licence Application

Date released
13 April 2022
Request number


Release of information under
Freedom of Information Act 2000 (FOIA)

Information requested

I would be grateful if you could arrange for the supply of the information requested below in relation to the Sizewell C Nuclear Site Licence Application.

On reviewing the DCO documentation, I note from the ONR's responses [DCO document reference REP8-168 and REP7-150] to questions raised by the Planning Inspectorate (PINS), that as of 24th September 2021 the ONR had not yet received the final versions of the Justification of Site Suitability Report (JSSR) nor the Site Data Summary Report (SDSR) from NNB GenCo.

Can you please:-
 (i) Advise whether you have now received the final versions of the JSSR and SDSR and, if so, when?

(ii) Advise, if the reports have been received, whether they have now been supplied to PINS?

(iii) Provide copies of these reports or links to them on the ONR website or, if not yet received, the dates expected.

From reviewing Table 1 in the ONR publication 'Licencing nuclear installations', can you please:-

(iv) Reference step 4A, advise whether BEIS have confirmed to the ONR that:-
a) BEIS have agreed a funded decommissioning programme with NNB GenCo?,
b) BEIS have agreed a position on nuclear liability insurance with NNB GenCo?

(v) Reference step 4B, advise whether the ONR have consulted with BEIS regarding NNBGenCo's financial standing and their nuclear liability insurance arrangements,

(vi) Provide copies of the documents setting out the funded decommissioning arrangements, the nuclear liabilities insurance and NNBGenCo's financial standing.

(vii) Provide the expected date of receipt for any information in (iv) and (v) above, if not yet received.

Information released

We confirm that under Section 1 of the FOIA, we hold the two documents described in part (iii) of your request. We are releasing the versions we hold of the JSSR and SDSR with redactions, as set out below, and these are attached to this response. Please be aware these are not the final versions for the following reason.

The JSSR and SDSR, respectively version 3 dated 29 September 2021 and version 4 dated 28 September 2021, were both provided to ONR on 30 September 2021.
These are not the final versions as some information within the documents do not reflect the current design intent. As we explained in our previous response dated 16 March 2022 (unique reference: 2022/16871), this is due to interactions between NNB and ONR, and also through NNB’s own design development since the issue of the documents. Updates relating to the design intent have been communicated to ONR in various ways, but they have not yet been captured in an updated version of the JSSR and SDSR.

We also confirm under Section 1 of the FOIA, we hold the information described in part (vi) of your request. We have identified one document in scope of your request: the draft Decommissioning and Waste Management Plan (DWMP) for Sizewell C. However, we are refusing your request to release this document under Section 22 (Information intended for future publication) of the FOIA.

Exemptions applied

22, 24, 40, 41, 43

PIT (Public Interest Test) if applicable


Absolute exemptions

Section 41 FOIA – Information provided in confidence

Section 41 sets out an exemption from the right to know where the information was provided to the public authority in confidence. This applies to information which was obtained by ONR from any other person, and its disclosure would constitute a breach of confidence, or a legal person could bring a court action for that breach of confidence and that court action would be likely to succeed.

We consider that information in relation to the potential commercial operation of Sizewell C which is not in the public domain has the necessary quality of confidence and given to ONR in circumstances imparting an obligation of confidence. In addition, we consider that disclosure of this type of information has the potential to be harmful to EDF and Sizewell C’s commercial interests and therefore should not be disclosed.

This includes information relation to seismic spectra frequencies which no longer represents the seismic design basis being adopted at Sizewell C, based on recent agreements with ONR. As work is still ongoing to fully converge between Sizewell C and ONR, this particular information is incomplete, and it would therefore provide an erroneous picture to anyone receiving the information.

This is an absolute exemption and so does not require the public interest test.

Section 40 FOIA – Personal information

We have also removed some information from the JSSR and SDSR as it is personal data. This consists of names and job titles. Release of each of this type of information could identify the individual either directly or indirectly. The personal data has been withheld using the exemption Section 40(2) of the FOIA.

Release of the information would breach principle (a) of GDPR (lawfulness, fairness and transparency) on the grounds that there is no lawful basis to process this data. In addition, releasing this personal data would also breach principle (b) of GDPR (purpose limitation) as the data was provided for the purposes of document control.

Qualified exemptions

In our previous response to you dated 16 March 2022, we set out that we were considering the public interest test in relation to the following exemptions of the FOIA.

Section 24 sets out the exemption from the right to know where the information requested is required for the purposes of safeguarding national security. It works to protect national security, which includes protection of potential targets. It allows a public authority not to disclose information if it considers releasing the information would make the UK or its citizens more vulnerable to a national security threat.

Section 43(2) exempts information whose disclosure would, or would be likely to, prejudice the commercial interests of any person (an individual, a company, the public authority itself or any other legal entity).

As these are qualified exemptions, we are required to balance the public interest between disclosure and non-disclosure. We have therefore applied the Public Interest Test, as set out below:

Factors for disclosure (Sections 24 and 43):

We recognise that there is considerable public interest relating to the location suitability of a proposed new nuclear site and how site-specific external hazards are considered in site suitability. This is particularly significant in the context of increasing public discourse and focus on climate change and its impact on weather patterns, flooding risks, and the environment.

Factors against disclosure (Section 24 – Safeguarding national security):


After careful consideration of the factors set out above, we have concluded that the specific information relating to locations and descriptions of building locations and activities, emergency preparedness and arrangements, and turbine missile strike risks should be withheld. There is a strong public interest in safeguarding national security. The interests of national security should be given significant weight in the above factors against disclosure and outweigh the need for openness in terms of these specific types of information.

Factors against disclosure (Section 43(2) – Prejudice to commercial interests):


There is a strong public interest in protecting the commercial interests of individual companies and organisations, and ensuring they are able to compete in the market fairly. In addition, some of the information described was provided in confidence to ONR. As a result it is in the public interest to withhold the information related to reactor trip frequencies, extreme high sea temperatures and extreme high air temperatures on the basis that publication of that information would be likely to prejudice the possible future commercial operations and commercial case for Sizewell C.

Overall conclusion on the JSSR and SDSR

We recognise there is significant public interest in providing information that would further understanding of the underpinning arguments and evidence regarding the justification of site suitability of the proposed Sizewell C site. As part of the Nuclear Site Licence (NSL) application, it must be shown that the proposed site represents a suitable location from a nuclear safety point of view. The JSSR and SDSR have been produced at an appropriate and proportionate depth to demonstrate this at the NSL application stage.

Based on our assessment of the factors set out above, we have concluded that it is in the public interest to disclose the versions of the JSSR and SDSR we hold, with the caveat these are not the final versions, subject to the limited types of information relating to safeguarding national security, commercial interests, provided in confidence, and personal data being redacted.

The DWMP for Sizewell C

We have considered the public interest test in relation to the following qualified exemptions of the FOIA.

Factors for disclosure:

Factors against disclosure:

The release of this information in advance of formal publication could lead to:

Conclusion on the DWMP

Based on our assessment of the factors above, the DWMP we hold should be withheld under Section 22 FOIA. It is not in the public interest to release the information at this stage, taking into account the fact it is a draft that has been shared with other public bodies along with ONR for review and comments, and is intended to be published by BEIS once it has been finalised and approved by the Secretary of State.