ML20029E937
| ML20029E937 | |
| Person / Time | |
|---|---|
| Issue date: | 01/27/2020 |
| From: | Gregory Chapman, John Clements, Lifeng Guo, Stephen Koenick, Michael Lafranzo, Leah Parks, Karen Pinkston, James Smith, Bruce Watson Division of Decommissioning, Uranium Recovery and Waste Programs |
| To: | |
| S Giebel | |
| Shared Package | |
| ML20029E935 | List: |
| References | |
| Download: ML20029E937 (23) | |
Text
Hematite Decommissioning Project -
Lessons Learned Greg Chapman, James Smith, Mike LaFranzo, Leah Parks, Lifeng Guo, Stephen Koenick, John Clements, Karen Pinkston, Bruce Watson. (an awful lot of people)
Site/Decommissioning History
- Site operated from 1956 until 2001 (license SNM-0033)
- Site decommissioning plan (DP) originally submitted 2004
- 8/12/2009 (accepted resubmittal)
- Amendment 52 allowing building demolition and disposal issued in 2006.
- DP approved 10/13/2011
- Original DP schedule was < 3 yrs
- Final Status Survey Report (FSSR) submitted piecemeal (Volumes and Chapters) beginning in 2015complete document received in March 2018
- Letter terminating license issued 9/30/2018
Significant site work Scope of Decommissioning
- 16 buildings reduced to 3 at time of FSS
- Removal of on-site burials
- FSS scope
- 69 Land Survey Units
- 10 Reuse Soil Stockpiles
- 55 Building Survey Units
- 12 Pipe Survey Units
- 6 Quarters of post-remediation GW monitoring
Challenging Planning Issues
- Criteria development
- layered vs uniform DCGLs for soil
- Warehouse vs small office for structures
- Trace radionuclides addressed by scaling down principle radionuclide DCGLs (U, Th, Ra, Tc-99)
- One principle radionuclide is notably difficult to detect via scanning (Tc-99) and environmentally mobile
- Allowed to use surrogate relationship for planning survey only
- Leaving behind some piping and miscellaneous structures
Upon completion of remediation, in its final excavated configuration as prepared for FSS, LSA 10-12 presents 1,578 square meters (m2 ) in planar (2-dimensional) extent, within an interior surface area of 1,926 m2 (3-dimensional).
Problematic Implementation Issues
- Removal/reuse of upper layers of cover soil
- Scanning initially insufficient to identify fuel fragments when performing 1 lifts
- Scanning sensitivity was increased by slowing speed and decreasing distance between surface and detector
- lifts decreased
- Modified criteria due to composite sampling as each truckload was evaluated for reuse
- Modified plan for reuse depending on analytical results of stockpile samples
- Isolation and control issues for soil stockpiles
- Had to use a soil scanner/sorter to partially reevaluate the soils already stockpiled
Problematic Implementation Issues
- Excavation sidewall issues
- Survey unit area
- Sampling of sidewalls
- Scanning of sidewalls
- Inaccessible areas
- In standing or running water
- Excavation sidewalls
- Gas pipeline
Problematic Implementation Issues
- Layered approach
- Assurance that reuse soil is properly accounted for
- Eventually decided it would be best to evaluate reuse soil separately and use only uniform criteria
- Licensee had to very carefully document depth of remaining soil and samples
- How to assess sampling statistically
- MARSSIM approach is using WRS test for surface soil only
Problematic Implementation Issues
- Elevated areas
- Using SU borders to define the elevated area
- Using scanning to define the elevation when insufficient samples taken
- Hard to detect radionuclides (Tc-99) were of particular difficulty to address (had to assume surrogate relationship)
Problematic Implementation Issues
- Structural Contamination Measurements
- Piping
- not 100% scanned
- Time frame of scan logging
- Structures
- Utilized ambient background
- Ventilation surveys
- Dose estimate didnt follow the approved method
- Didnt use proper calibration (on-site calibration is modified from off-site calibration)
Problematic Implementation Issues
- Post-remediation groundwater monitoring Frequency and length of monitoring No specific requirements on provided in either regulation or guidance documents (e.g., NUREG-1757)
A minimum of four (4) Quarterly sampling Monitoring network Silty clay Sand/gravel aquifer Bedrock aquifers Statistical analysis to confirm stability of levels of radionuclides of concerns (e.g., Mann-Kandell trend test)
Best Practices
- A quality licensee product speeds up the acceptance/review
- Pre-submittal audits could help assure a quality incoming product and understanding of novel approaches to decommissioning
- Routinely scheduled public teleconferences
- More coordination/documentation for PM
- Consider adjusting the frequency based on work being performed
- Modifications should be incorporated into the original document (revisions of original)
Best Practices Contd.
- Be careful with piecemeal reviews
- Feedback on initial documents is generally helpful
- Can devolve into consulting vs helping
- Misunderstanding of schedule impacts (licensee vs staff expectations)
- For long, involved documents, vertical and horizontal slice review makes the project manageable
- Similar to inspections and FCSE ISA reviews
- Good communication and attitude between all involved
- Call out mistakes having negligible impact but not requiring revision
Greg Chapman CHP, PE NRC NMSS/DUWP/URMDB Gregory.Chapman@nrc.gov 301-415-8718