Fig. 1.
![Decay of VHLW from reprocessing 1 metric ton of SF (p. 17 in Ref. [1]).](https://sciendo-parsed.s3.eu-central-1.amazonaws.com/68a8bde5afc50a4de0964f13/j_nuka-2025-0009_fig_001.jpg?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential=AKIA6AP2G7AKOUXAVR44%2F20251128%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20251128T134424Z&X-Amz-Expires=3600&X-Amz-Signature=3ac7a5dc31872979c8d37976fc88366bffce423508640e20b44294e23186afa1&X-Amz-SignedHeaders=host&x-amz-checksum-mode=ENABLED&x-id=GetObject)
Fig. 2.
![Decay of activity content of 1 metric ton of Swedish SF (p. 16 in Ref. [3]).](https://sciendo-parsed.s3.eu-central-1.amazonaws.com/68a8bde5afc50a4de0964f13/j_nuka-2025-0009_fig_002.jpg?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential=AKIA6AP2G7AKOUXAVR44%2F20251128%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20251128T134424Z&X-Amz-Expires=3600&X-Amz-Signature=8c9d3504a2be37ccf3255a4c63b4968282ea65b68b92fddcc4eb20431c08aeaf&X-Amz-SignedHeaders=host&x-amz-checksum-mode=ENABLED&x-id=GetObject)
Fig. 3.
![External radiation 1 m away from 1 metric ton of Swedish SF (p. 23 in Ref. [3]).](https://sciendo-parsed.s3.eu-central-1.amazonaws.com/68a8bde5afc50a4de0964f13/j_nuka-2025-0009_fig_003.jpg?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential=AKIA6AP2G7AKOUXAVR44%2F20251128%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20251128T134424Z&X-Amz-Expires=3600&X-Amz-Signature=84a992998e76da0f9804ac5476ebc8bc5dfdfd7560d1c433845d03708373904d&X-Amz-SignedHeaders=host&x-amz-checksum-mode=ENABLED&x-id=GetObject)
Fig. 4.
![Radiological dose rate, in Sv/h, 40 cm from two French HLW drill cores. The C2 drill core is VHLW; the CU1 drill core is SF (p. 533 in Ref. [5]).](https://sciendo-parsed.s3.eu-central-1.amazonaws.com/68a8bde5afc50a4de0964f13/j_nuka-2025-0009_fig_004.jpg?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential=AKIA6AP2G7AKOUXAVR44%2F20251128%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20251128T134424Z&X-Amz-Expires=3600&X-Amz-Signature=8dce3c158bc1dab6e11722e982ef6756c6a7541bdba3e30c339df3b8bd3a5658&X-Amz-SignedHeaders=host&x-amz-checksum-mode=ENABLED&x-id=GetObject)
Fig. 5.
Fig. 6.
![Accrued, external dose from drill cores of several kinds of present and future French VHLW after a 10-min exposure, 40 cm from the drill core, and as a function of time (p. 352 in Ref. [9]).](https://sciendo-parsed.s3.eu-central-1.amazonaws.com/68a8bde5afc50a4de0964f13/j_nuka-2025-0009_fig_006.jpg?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential=AKIA6AP2G7AKOUXAVR44%2F20251128%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20251128T134424Z&X-Amz-Expires=3600&X-Amz-Signature=6b747f72a694d495b1fe2af10e9313e260f7c1f2a9bee70858a7a01449ff2909&X-Amz-SignedHeaders=host&x-amz-checksum-mode=ENABLED&x-id=GetObject)
Decay constants in per-million-year units
| Chain | λ |
|---|---|
| U-238 | 1.55 × 10−5 |
| Excess U-234 | 2.82 |
| Np-237 | 0.324 |
Calculated shield thicknesses at 1 million years depending on each nuclear chain and using the proximity criterion_ In bold are the required envelope thicknesses for each waste form_ These values will decrease in time to reach the values for U-238, reported in italics
| Surface dose rates | C2 VHLW full-size | C2 VHLW drill core | 8 PWR SF assemblies | CU1 SF drill core |
|---|---|---|---|---|
| S238 | 16.6 | – | 61.9 | 41.1 |
| S234 | 24.3 | – | 57.3 | 36.5 |
| S238 + S234 | 28.8 | – | 67.5 | 46.7 |
| S237 | 53.5 | 48.1 | 43.5 | 28.2 |
Gamma dose rate (mSv/h) at three distances from a Pollux-8 cask loaded with eight PWR UO2 fuel assemblies, neglecting the shielding of the cask [2]
| Decay time (million years) | Surface (4 cm) | Surface (2 cm extrapolated) |
|---|---|---|
| 1 | 6.6 | 13.1 |
| 10 | 2.8 | 5.5 |
| 100 | 2.7 | 5.4 |
| 1000 | 2.3 | 4.6 |
Calculated shield thicknesses at 1 million years depending on each nuclear chain and using the tolerability criterion_ In bold are the required envelope thicknesses for each waste form_ These values will decrease in time to reach the calculated for U-238, reported in italics
| Surface dose rates | C2 VHLW full-size | C2 VHLW drill core | 8 PWR SF assemblies | CU1 SF drill core |
|---|---|---|---|---|
| S238 | 42.1 | 5.2 | 87.4 | 66.6 |
| S234 | 49.8 | 13.5 | 82.7 | 61.9 |
| S238 + S234 | 54.3 | 17.8 | 93.0 | 72.2 |
| S237 | 72.2 | 66.9 | 62.2 | 46.9 |
Dose rate (mSv/h) 2 cm from reference unshielded VHLW and SF at 1 million years [2]
| Surface dose rates | C2 VHLW full-size | C2 VHLW drill core | 8 PWR SF assemblies | CU1 SF drill core |
|---|---|---|---|---|
| S238 | 0.09 | 0.0032 | 5.4 | 0.82 |
| S234 | 0.18 | 0.0068 | 3.54 | 0.54 |
| S237 | 14.42 | 7.45 | 4.2 | 0.64 |
| Total | 14.69 | 4.46 | 13.14 | 2.00 |