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3.3 Evaluation of the radiological impact in the case of the variant human intrusion scenario
In the considered human intrusion scenario it is assumed that a core from exploratory drilling is
subjected to laboratory analysis by a geotechnical worker (although some difficulty might be expected
in successfully coring the waste because of the presence of a thick metallic container). A
number of activities during laboratory analysis of core material can give rise to exposure via inhalation,
ingestion and external irradiation. The core inspection scenario defined by Kelly and Jackson
[12] is used. The calculated doses to a geotechnical worker are shown in Fig. 5. Also shown in this
figure is the dose to a geotechnical worker examining natural uranium ore; the Cigar Lake uranium
ore is used here as a reference, which has an average uranium grade of 8%.
Dose (Sv)
1x10 2
1x10 1
1x10 0
1x10 -1
1x10 -2
1x10 -3
1x10 -4
1x10 -5
10 2
A1 SF
A2 HLW
A2 MOX SF
A3 HLW
B1 HLW
B2 HLW-ADS
B2 HLW-MOX
B2 HLW-UOX
Upper ICRP IL
Lower ICRP IL
Cigar Lake NA
10 3
147
10 4
Time (year)
Figure 5: Doses to a geotechnical worker for the 5 considered fuel cycle scenarios
(IL: intervention level; NA: natural analogue).
4. Discussion
High-level radioactive waste arising from advanced fuel cycles generates significantly less heat
than does the equivalent amount of spent fuel arising from the "once through" fuel cycle. The
smaller thermal output of the waste allows a reduction in the size of the SF and HLW repository
needed per unit produced electricity. For instance, the greatest reduction in needed length of disposal
galleries is observed for fuel cycle B1 (fast reactor with multi-recycling of the actinides), a
reduction with a factor 2.5 (granite) to 3.2 (clay) in comparison with the reference fuel cycle A1.
The reduction factor of the needed surface area of the repository can even be higher than that for the
gallery length, when the distance between two disposal galleries is also optimised, respecting the
minimum distance between two galleries imposed by geomechanical limitations.
The calculated doses in the reference scenario are, for all considered fuel cycles, far below the dose
constraint of 0.3 mSv/a proposed by ICRP [13]. The impact of the application of P&T in a fuel cycle
on the maximum dose resulting from the disposal of the generated spent fuel or HLW is rather
limited, because the maximum dose is essentially due to mobile long-lived fission and activation
products. The amount of generated fission products is about proportional to the heat produced by
10 5
10 6