Sizewell C external hazards proportionate reassessment

Date released: 18 November 2024
Request number: 202409002
Release of information under: Environmental Information Regulations 2004 (EIR)

Information requested

(In respect of the ‘External hazards proportionate reassessment’)

3. Para 56 refers to ‘Overland flood barriers’ (OFB) and states, “The role of the overland flood barriers is to ensure that water surrounding the site is less than the platform height, ensuring that the SZC site remains protected; see [51] and [52].”

Please provide the documents at

[51] ‘NNB GenCo (SZC), “SZC Platform Height: ALARP Analysis Decision Paper, Version 3,” 2017, SZC-NNBOSL-U9-ALL-RES-100000 (CM9 2017/208858)’ and

[52] ‘Atkins/NNB GenCo, “Sizewell C Coastal Flooding ALARP Phase 2 - Flood Levels Analysis, Issue 2,” 2015, SZC-NNBOSL-XX-000-RET-100001, (CM9 2017/208852).’ and

[53] ‘ONR Expert Panel on Natural Hazards, “Expert Panel on Natural Hazards - SZC Credible Maximum Scenario - e-mails,” 29 February and 04 March 2024 (CM9 2024/10071).’

4. Para 57 appears to refer to the need for the OFBs to be capable of meeting ‘Credible maximum climate change’ and that the ‘Estimated minimum crest height’ for the Northern and Southern OFBs is +10mOD and +9mOD respectively. However, Appendix 3 refers to the OFB being 6.4 metres AOD (being the ‘platform height’). In the DCO examination, the platform height was increased to 7.3 metres AOD. Please confirm the height set in the most up to date proposals for the OFBs and provide a copy of those proposals confirming the anticipated height.

7. Para 58 refers to updated wave analyses being due from SZC Ltd by quarter 1 2024 and SDSR Rev 6 also due. Please advise whether these reports have now been submitted to ONR and, if so, provide copies. If not, please advise when the ONR expects to receive them.

10. Please provide copies of the following documents listed in Section 7:-

[24] EDF R&D UK Centre, “Update to Estimation of extreme high-water levels at SZC, Revision 3,” SZC-PD0202-XX-000-REP-100005, 2021, (CM9 2021/73776).

[37] SZC Ltd, “SZC Ltd. Station Milestones - re. ONR Letter - sea defence design dates - e-mail,” 31 January 2024 (CM9 2024/6070).

Information released

We confirm that we hold the information you have requested in Parts 3, 4, and 10 of your letter. Please find the five documents specified in your request attached. Please find the five documents specified in your request attached. Please note that [53] ‘ONR Expert Panel on Natural Hazards, “Expert Panel on Natural Hazards - SZC Credible Maximum Scenario - e-mails,” 29 February and 04 March 2024 (CM9 2024/10071) is contained across two documents.

In relation to Part 4 of your letter regarding the most up to date proposals for the overland flood barriers, Appendix 3 of ONR’s External hazards proportionate reassessment of an application by Sizewell C Limited for a Nuclear Site Licence does not refer to the overland flood barrier height. It refers to a proposed site platform height of 6.4m above ordnance datum (AOD); the proposed site platform height was later revised to 7.3m AOD. A site platform height of 7.3m AOD is referred to in ONR’s External hazards proportionate reassessment of an application by Sizewell C Limited for a Nuclear Site Licence and the External hazards assessment of an application by NNB Generation Company (SZC) Ltd for a nuclear site licence.

In relation to Part 7 of your letter regarding updated wave analyses, we do not hold this information as we have not yet received these reports. We have regular engagement with Sizewell C Ltd on the progress of the analyses; as this process is ongoing, we are unable to provide a timeline for their submission at this time.

Regulation 12(5)(e) - Confidentiality of commercial or industrial information

In relation to [51] ‘NNB GenCo (SZC), “SZC Platform Height: ALARP Analysis Decision Paper, Version 3,” 2017, SZC-NNBOSL-U9-ALL-RES-100000 (CM9 2017/208858) and [24] EDF R&D UK Centre, “Update to Estimation of extreme high-water levels at SZC, Revision 3,” SZC-PD0202-XX-000-REP-100005, 2021, (CM9 2021/73776), we have identified that these contain commercially sensitive information or information that would be of commercial interest to competitors.

Regulation 12(5)(e) of the EIR sets out the circumstances where a public authority may refuse to disclose information to the extent that its disclosure would adversely affect the confidentiality of commercial or industrial information where such confidentiality is provided by law to protect a legitimate economic interest. More information can be found in the following relevant guidance available on the Information Commissioner’s Office website.

As Regulation 12(5)(e) is a qualified exception, we have therefore applied the public interest test as set out below.

Regulation 13(1) EIR – Personal data

Please also note that some information across the five documents has been withheld under Regulation 13(1) of the EIR. Regulation 13(1) of the EIRs exempts information from disclosure where the information is the personal data of someone other than you and the disclosure of that personal data would put us in breach of the principles of the Data Protection Act 2018 with which we are obliged to comply.

We have withheld the names, job titles, contact details, and signatures recorded in the documents we have released as we consider this information relates to the personal data of specific individuals working at EDF Energy, Sizewell C, ONR, and others who are not public facing and would not expect their details to be made public. Disclosure of this information would be in breach of the Data Protection Principle and, as such, is exempt from disclosure under Regulation 13(1) of the EIRs.

Further information

We note that some of the documents enclosed contain security markings however have been deemed appropriate to release in response to your request. As such, the security status on the documents become null and void once released under the EIR.

Exemptions applied

r.12(5)(e), r.13(1)

PIT (Public Interest Test) if applicable

Factors for disclosure

Regulation 12(2) of the EIR requires public authorities to apply a presumption in favour of disclosure;

ONR is committed to being an open and transparent regulator. We will use openness and transparency to achieve our objective of developing and maintaining stakeholder trust in ONR as an effective independent regulator;
The public have a vested interest in issues related to the nuclear industry, facilitating accountability and transparency; and,
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, such as sea levels, 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

The commercial nuclear industry is highly competitive. Releasing financially sensitive information such as baseline costing assumptions in construction and operational costs options within the report would provide competitors access to commercially valuable information that would not have been available to them otherwise. It is in the public interest to protect legitimate economic interests where care has already been taken to ensure certain commercial or industrial information has not already been disseminated to the general public;
Information relating to statistical methodology used by Sizewell C Ltd has been shared in confidence with ONR as a regulator. Disclosure of how various statistical methodologies have been considered when applied to Sizewell C Ltd ’s proprietary data and costs impacts would undermine the confidential industrial nature of this information, and would allow competitors to gain an advantageous insight; and
Disclosure of these kinds of sensitive commercial and industrial information may result in commercially significant reputation damage or loss of revenue or income to Sizewell C Ltd should competitors gain access to such confidential information.

Conclusion

Having carefully considered the factors above in relation to the information identified in two of the documents, we have decided that the factors for non-disclosure outweigh the reasons for disclosure.

It is in the public interest to protect legitimate economic and industrial interests. It is well known that a release under the EIR is considered to be a ‘release to the world at large’. We consider that the financial information and statistical methodology analysis in the reports has the necessary quality of commercial or industrial information in nature, and an unrestricted release of the report would be likely to cause harm to Sizewell C Ltd as any other individual or party could gain access to confidential and commercially valuable information, and thus damage their economic interests.

However, we recognise that there is strong public interest in the subject matters raised. To the strike the appropriate balance, we are therefore releasing the requested reports with the limited sensitive financial information in section 8.1, table 5 and section 12 of [51] ‘NNB GenCo (SZC), “SZC Platform Height: ALARP Analysis Decision Paper, Version 3,” 2017, SZC-NNBOSL-U9-ALL-RES-100000 (CM9 2017/208858) as well as information on statistical methodology in section 3 of [24] EDF R&D UK Centre, “Update to Estimation of extreme high-water levels at SZC, Revision 3,” SZC-PD0202-XX-000-REP-100005, 2021, (CM9 2021/73776) withheld for the factors set out above.