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XRN 5635
H100 (UNC Mod799) Consequential Gemini Change

Last Updated
15 Nov 2023
Release Type
Implementation Date
Proposer National Gas Transmission Impacted DSC service area


Not applicable

Customer Change Team Leader


Transporters in discussion with Correla have agreed on the below option to meet the CV validation rule challenge.

Option 3 - Create a specific CV Tolerance Range for the new meters for the relevant file types


This solution would involve each new hydrogen meter having a specific range not linked to the meter type.


The implementation of H100 is currently scheduled for June 2024.


Gemini Sustain Plus

In order to provide the decision makers with enough relevant information, the solutions assessed in the Design phase need to take into consideration the on-going Gemini Sustain Plus programme (XRN5564).


Please can all the following delivery options be costed and associated risks be provided as part of the BER process.


1)         Delivery into Legacy Gemini – before Service Extraction of the relevant microservices have taken place.

2)         Delivery into Legacy Gemini and new Gemini post Service Extraction of the relevant microservices

3)         Delivery only into the updated Gemini platform. This solution will also need to consider an off-line interim solution (between June 2024 and September 2024)

Impacted Customer Types

  • DNO
  • NGT


Document title Comment Last updated CHMC outcome
Change Proposal CP raised 14/06/2023 Approved at ChMC 09/06/23
Initial Review Stage not yet reached N/A N/A
DSG Discussion N/A 26/06/2023 N/A
High Level Solution Options Stage not yet reached N/A N/A
Solution Review Stage not yet reached N/A N/A
Detailed Design Stage not yet reached N/A N/A
Evaluation Quotation Reports (EQR) Stage not yet reached N/A N/A
Business Evaluation Reports (BER) Stage not yet reached N/A N/A
Change Completion Reports (CCR) Stage not yet reached N/A N/A


Initial Review
Change Proposal raised 23/03/23
Status For voting at ChMC 09/06/23
Approved into development 09/06/23
Status ChMC approved
Solution Consultation
Expected: 00/00/00
Status Awaiting
Awaiting Delivery
Agreed the change will proceed with Solution Option 3 15/11/23
Status Gemini Sustain Plus
In Delivery
Expected: 00/00/00
Status Awaiting
Expected: 00/00/00
Status Awaiting

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