1. Swedish Radiation Protection Authority
Radiological Survey of the Active Central Laboratory (ACL) in Studsvik, Sweden
Henrik Efraimsson
Swedish Radiation Protection Authority
(SSI)

2. Contents The facility Decommissioning activities
Radiation protection of workers
Conditions for clean-up activities
Radiological survey
Documentation of the work

3. The Active Central Laboratory
Studsvik
Arnhem

4. ACL cross-sections
Ground floor

5. Decommissioning activities
Dismantling of equipment in the 90´s
Decommissioning project started 1998
Main tasks: removal of service systems, clean-up and measurements
Finished in 2004
Application for clearance and demolition in 2005

10. Radiation protection of workers
Low-level radiation fields
Protection measures during dust-generating activities
No external or internal radiation doses above the limits for registration and reporting

11. Conditions for clean-up
The licence holder shall
perform reasonable clean-up activities,
show compliance with EU recommendations RP 113 for the expected nuclides,
make nuclide specific measurements of residual activity,
search for spot activity if spots are suspected,
disregard naturally occurring activity that cannot be attributed to operations in the facility,
take measures against re-contamination.

12. Radiological survey Mapping with a grid of 1 m2 squares.
Measurement of residual activity by
Direct measurement with hand-held scintillation counter (100 cm2 sensitive area)
Smear samples (smeared area 100 cm2) for analysis with scintillation counters
Alpha, beta and gamma specific analysis of samples
In-situ gamma spectroscopic (ISOCS) measurement of several m2 at once.

13. Radiological survey, cont.
Documentation of measurement results.
Eventual removal of contaminated material.
Eventual complementary scintillation measurements.
Confirming in-situ gamma spectroscopic measurements.

14. Detected nuclides Analysis of samples:
Co-60, Sr-90, Cs-134, Cs-137, Eu-152, Eu-154, Eu-155, U-234, U-235, U-238, Pu-238. Pu-239, Pu-240, Am-241, Cm-244
In-situ gamma measurements:
Co-60, Cs-137 and Am-241
(a-emitting Pu / Am-241  3)

15. Survey methods

16. Extent of survey – wall example
3) Gamma-
spectroscopic
measurement
Scintillation measurements
1) Smear samples
1 m2
2) Hand-held instruments

17. Required documentation
Description of activities during operation
Description of clean-up activities
Description of survey methods
Transparent measurement results
Estimation of residual activity
Description of measures to prevent re-contamination