ML17160A084
| ML17160A084 | |
| Person / Time | |
|---|---|
| Site: | Humboldt Bay |
| Issue date: | 11/19/2014 |
| From: | Pacific Gas & Electric Co |
| To: | NRC Region 1 |
| References | |
| Download: ML17160A084 (31) | |
Text
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&~* Agenda 2
- HBPP Decommissioning Status and Schedule
- Gardian System
- Caisson Removal Retaining Wall Option
- CSM Wall Description and Characterization Plans
- Potential L TP Changes
- LTP Approval Schedule
Decommissioning Status and 3 Schedule
- Unit 2 excavation and remediation nearing completion
- Hot shop above grade demolition complete
- SAS building above grade demolition complete
- Currently removing RPV cut "windows"
- Spent fuel pool liner removal progressing I
Decommissioning Status and 4 Schedule (Cont'd)
- Gardian system installed for soil processing
- Discharge canal isolated from the bay
- Ground water treatment and pre-treatment system operational
- Soil management facility complete and in use
- Final site permit and Remedial Action Plan nearly ready for submittal
&~ 2015 Schedule Milestones 5
- July 2015 Discharge Canal Remediation Complete
- May 2015 Pre-Trenching Complete
- January 2016 Complete Water Cutoff Wall
6 Hot Shop Demolition
&~~ SAS Building Demolition 7
Soil Management and Pre-treatment 8 Facilities I Ji I
9 Groundwater Treatment Facility
10
- s Sheet Pile for Canal Isolation
11
- & Gardian System Installation
12 Unit 2 Remediation
13
- & Waste Shipment
14 Gardian System TBD
- System previously used at Big Rock Point
- Contains 4 Canberra In-Situ Object Counting System (ISOCS) characterized detectors.
- A complete Validation and Verification (V&V) of each detector's characterization file has been completed as part of pre-operational system testing.
- The Big Rock Point Technical Basis Document (TBD) has been revised for Humboldt Bay Power Plant specifics.
- The TBD will be submitted to NRC for review.
15 Caisson Removal Retaining Wall
- Outer water cutoff wall with excavation to remove SFP and install sheet piling for lower caisson removal is the feasibility study provided to CPUC
- Contractor proposed a different alternative using CSM (Cutter Soil Mix) technology but award was bounded by feasibility approach
- CSM alternative may be used in addition to water cutoff wall from the surface for caisson removal
16 CSM Installation Water/Cement Injected Water/Bentooite Injected
~
Foons CSM Loosens ~ Wall and Sizes Soil Equ1>fnent Side View
17
- & Cutter Soil Mix (CSM) Machinery
.&r CSM Cutter Head 18
19
.s CSM Installation
20
.&r Water/Soil Excess Removal
21 Completed Panel
&~* Discharged Material 22
23 CSM Wall with Ring Steel x 2.8 S<:IL 1111 p
El.. 6 El. 1 o* ( .)
El.. 16 El.
El. 4 q *- o El. 56 El.
El.. 16 El. a
-t io* c::H rr 0 1** I-
~ - ----
&~* Potential CSM Wall Example Diagram 24 110' C~LL WITH 3 METER THICK WALL
~
rei=ITTER OF REACTOR AND CAISSON
25 Reasoning for Potential CSM Wall
- Prevents un-shored excavations
- Installed completely from ground level
- Minimizes on-site excavation equipment
- Reduces volume of material to be handled
- Encompasses the spent fuel pool
&~* Challenges to CSM Wall Installation 26
- Wall construction utilizes displaced soils as part of the construction material
- CSM wall will be left in place at license termination
- Residual activity within the CSM wall will potentially affect future groundwater dose
27 CSM Wall Soil Sampling
~- Soil impacted Geo probe by CSM wall sampling in soils around where CSM wall will be placed
Calculating Future Groundwater 28 Dose
- Core bore sampling could assess the activity inventory in the CSM wall to remain and characterize soil outside of the wall
- A basement fill model could be used to determine the potential dose contribution to groundwater from the CSM wall
- The dose contribution from the CSM wall would have to be included with any other dose pathways in demonstrating the area meets the License Termination Rule of 25 mrem/yr plus A LARA I_ ~
29 NRC Approvals Requirement
- 1) If no activity found in soil, no approval required.
- 2) If activity less than soil DCGL, treat wall as soil and no approval required.
- 3) If activity greater than soil DCGL, use a basement fill model to determine potential dose to groundwater pathway.
For number 3, PG&E would submit a request to the NRC for approval of the basement fill model methodology. Supporting technical information will be provided in a Technical Based Document (TBD) requiring NRC approval.
30 L TP Approval Schedule
- Any Outstanding NRC Items Needing Resolution to Approve L TP Revision 1?
- Projected Date for NRC Approval