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XRN 5564
Gemini Sustain Plus Programme

Last Updated
16 May 2023
Release Type
Implementation Date
Proposer National Gas Transmission Impacted DSC service area

Service Area 14 (Current Apr 21)

Gemini Services

Customer Change Team Leader


NGG wishes to modernise the Gemini platform in order to continue to provide required Capacity & Balancing Services as well as delivering system compliance against new UNC modifications. NGG also wants to deliver change more efficiently whilst improving the customer experience.


The change will be known as the Gemini Sustain Plus programme. The scope of delivery will include:

  • Conversion of all the current Gemini functionality and code into modern (Java Microservices) code
  • Delivery of additional functional requirements
  • Delivery in line with non-functional requirements
  • Consolidation and re-design of Gemini screens
  • Implementation of Azure cloud infrastructure components (including replacing the current Oracle database)
  • Improvements to the support service arrangement to respond better to incidents and change (in line with new service levels and KPIs)


NGG require all of the programme scope to be delivered within a 2- year period, implementation to be specified in the Correla Delivery Plan.


Xoserve will contract with Correla to underpin the delivery of the Gemini Sustain Plus (covering the Correla Statement of Work).

Impacted Customer Types

  • NGT
  • Shipper
  • DNO


Document title Comment Last updated CHMC outcome
Change Proposal Approved into Capture  17/10/22 Approved at ChMC 12/10/22
Project Update N/A 16/05/23 N/A
Evaluation Quotation Reports (EQR) Stage not yet reached N/A N/A
Business Evaluation Reports (BER) N/A 14/11/2022 Approved at ChMC 09/11/2022
Change Completion Reports (CCR) Stage not yet reached N/A N/A


Initial Review
Change Proposal Raised 28/09/22
Status Awaiting approval into Capture at ChMC 12/10/22
Approved into Capture 12/10/22
Status ChMC approved into Capture
Solution Consultation
Expected: 00/00/00
Status Awaiting
Awaiting Delivery
Expected: 00/00/00
Status Awaiting
In Delivery
Expected: 00/00/00
Status Awaiting
Expected: 00/00/00
Status Awaiting

Contact the Change Team

Need to get in touch with a member of the Change Team?

You can email us at: and we'll get back on the same day between the hours of 9:00am to 4:30pm.