Independent Peer Review of - Low Level Waste Repository Ltd

Peer Review of LLWR Response to S9R2LLWR_2008-8-2Version 1The pros and cons of retrieval from the trenches of localisedvolumes of waste possessing relatively higher concentrations oflong-lived radionuclides need further analysis.140. In April 2008, the peer review panel suggested that SLC should not bedefinite on the need for the vertical drains, the vault base liner, or the cutoffwalls – this is still our view. These features are still part of theproposed strategy, but the submission and the SLC recognise the need forfurther optimisation of the design, and we support this.141. Overall, therefore, the peer review panel is now more comfortable andable to support the main conclusions on strategy proposed in thesubmission.5.4 Forward Programme142. We have made various detailed technical suggestions in Section 3 and 4regarding issues that could be considered in the forward programmeleading to the next safety case. Here we highlight just a few key points:There is only a short period in which to develop the next safety case.Simply documenting the safety case might take a year towards theend of the period. Good planning will be essential if the variouscomponents of the safety case are to be brought together at the righttime and with appropriate levels of consistency, quality assuranceand peer review. It would seem sensible, therefore, for the SLC tomaintain the valuable momentum developed during recent months.The next safety case will need to include a safety assessment thatincludes a more comprehensive treatment of uncertainty. Planningthe approach to the treatment of uncertainty should probably be oneof the more strategic issues that should be considered at an earlystage.There is a need to better integrate the engineering design andoptimisation work with the safety case. Decisions on facilityoperation should be checked for consistency with the environmentalsafety cases.The risks from coastal erosion of the facility need to be assessed in athorough and robust way. A more convincing and well-supported understanding ofgroundwater movements and potential radionuclide transport shouldbe demonstrated in order to confirm that ground and surface waterpathways are now a less prominent issue in long-term performance.TerraSalus Limited 32 2 September 2008