RD&D-Programme 2004 - SKB

A system for documentation of the long-lived waste has been developed by SKB. The system
resembles the one for SFR waste, but also takes into account the fact that documentation takes
place progressively. This is due to the fact that the waste is in some cases stored as raw waste
for a long time before being given its final form for disposal.
Conclusions in RD&D 2001 and its review
SKI concludes that it is reasonable to focus the work on the radionuclides that contribute most
to the calculated dose, such as chlorine-36 and molybdenum-93, but that SKB should also be
prepared to study other nuclides that may be important at the next safety assessment.
Newfound knowledge since RD&D 2001
The long-lived LILW will be kept track of by SKB in a similar way as the waste destined for
SFR. With time, this will give us a better picture of the radionuclide inventory in the waste.
Studies have been conducted on behalf of SKB at the Division of Nuclear Physics at Lund
University to reduce the detection limit for nickel-59 in steel material. An earlier measurement
method was mainly developed with regard to specimen preparation. The detection limit has
been reduced by a factor of 20 compared with the previous level. In recent years, measurements
have been performed on both steel material from BWR reactors and reactor water from PWR
reactors.
A project has been started at the same division at Lund University to measure carbon-14 in ion
exchange resins from Swedish reactors. Previously, carbon-14 has been measured in graphite
from the decommissioned research reactor at KTH in Stockholm. Literature reviews have been
conducted for the purpose of identifying suitable measurement methods for carbon-14 measurements
in ion exchange resins.
SKB has also had measurements performed of the chlorine content of steel material at Imperial
College in London. The purpose of these measurements was to permit more accurate calculation
of the content of chlorine-36 in steel material from the Swedish reactors. The detection limits
in these measurement series varied between 0.14 and 1.5 mg/kg (ppm). The majority of the
specimens that were analyzed lay below the detection limits. The project entailed that an earlier
method for cleaning of specimens had to be modified to prevent the chloride content from being
affected in cases where the specimens contained quantities of molybdenum and tungsten.
Programme
See section 25.5.
25.3.1 Final repository for other long-lived waste
A layout for the final repository for other long-lived waste was prepared in 1996. This repository
was to be able to receive long-lived LILW /25-1/.
Conclusions in RD&D 2001 and its review
The authorities /25-2/ note the lack of a coherent account of design studies and design requirements
as well as requirements that must be made on a candidate site in order for it to meet the
requirements made on the design of the final repository for other long-lived waste.
Newfound knowledge since RD&D 2001
SKB has not conducted any new studies of this nature.
330 RD&D-Programme 2004