ALARA Program and RP Activities for the Reactor Vessel Head Replacement in Vandellòs II NPP

Transcription

1 ALARA Program and RP Activities for the Reactor Vessel Head Replacement in Vandellòs II NPP Anna Prim-Pujals, Radiation Protection, Vandellòs II NPP 2015 ISOE International ALARA Symposium, Brussels

2 Content 1. Vandellòs II NPP: why RHVR? 2. Reactor vessel head dose rate evolution 4. Dose Results Summary 5. Information and procedures 6. Learned lessons 2

3 1. Vandellòs II NPP: why RHVR? Owners ANAV ( + ) Technology Cooling Power Westinghouse 3 loop Pressurised Water Reactor (PWR) Mediterranean sea and aircoolers. Forced draught cooling towers and safeguards pool recently implemented (2009) 1, Mwe Start-Up Date of Current Operating Permit March Spent Fuel Pools Saturation

4 1. Vandellòs II NPP: why RHVR? Operative international experience: PWSCC in NPP with Inconel 600 /82 /182 in the pressure barrier Inconel 600 in the CRDM penetrations, thermocouples columns Possible wear in thermal sleeves (specific Westinghouse issue) Successive inspections: no cracking problems detected Preventive measure: replacement of the vessel head by a necover with an improved design with Inconel 690 /52M / 152M 4

5 2. Reactor vessel head dose rate evolution ,24 msv/h 0,5 msv/h 0,5 msv/h ,73 msv/h 1,2 msv/h 3,3 msv/h ,28 msv/h 0,3 msv/h 0,4 msv/h ,42 msv/h 1 msv/h 3,5 msv/h ,28 msv/h 0,4 msv/h 0,5 msv/h ,85 msv/h 1 msv/h 3,2 msv/h 5

6 PLANT MODIFICATIONS NEW HEAD PHASE 1 PHASE 2 New platform at Containment hatch New gate for the entrance to the Fuel Conditioning of the Waste Storage 6 CDRM installation in the new vessel head in the Fuel Transport of the new vessel head to the Containment Assembly of the reusable items on the new head Disassembly of the reusable items from the Transfer of the to the Fuel Storage of the old vessel head in the Fuel CDRM disassembling and conditioning in the Fuel Transport of the and the CRDM to the Waste Storage

7 NEW HEAD CDRM installation in the new vessel head in the Fuel Transport of the new vessel head to the Containment Activity Assembly of the reusable items Man hours Inverted Estimated Man msv Reestimated Received ,271 Assembly of the reusable items on the new head No significant radiological concerns

8 PHASE 1 Disassembly of the reusable items from the Transfer of the to the Fuel Activity Partial dissassembly of insulation Disassembly of the reusable items Man hours Man msv Inverted Estimated Re-estimated Received , ,439 Scaffolding ,105 Shielding ,715 The shroud is the last reusable part to be removed. Opportunity to install additional shielding. Storage of the old vessel head in the Fuel Dose re-estimation

9 PHASE 1 Disassembly of the reusable items from the Transfer of the to the Fuel Storage of the old vessel head in the Fuel

10 PHASE 1 Disassembly of the reusable items from the Transfer of the to the Fuel Storage of the old vessel head in the Fuel Activity Man hours Inverted Estimated Man msv Reestimated Received Preparation and Decontam ,772 Transfer to the Fuel ,125 Head vessel transfer much faster than expected (36 h estimated / 8 h inverted)

11 PHASE smear samples before the vessel head exits out of the Containment (all < 0,4 Bq/cm 2 ) Disassembly of the reusable items from the Transfer of the to the Fuel Storage of the old vessel head in the Fuel

12 PHASE 1 Disassembly of the reusable items from the Affected outside areas: > 25 µsv/h 1 msv/h > 3 µsv/h 25 µsv/h > 0,5 µsv/h 3 µsv/h Transfer of the to the Fuel Storage of the old vessel head in the Fuel

13 PHASE 1 Disassembly of the reusable items from the Transfer of the to the Fuel Storage of the old vessel head in the Fuel Teledosimetry 16 remote monitoring DLD + 6 additional transmitters 1 personal computer 6 TLD

14 PHASE 1 RP checkpoints (entrance to the restricted area) Maximum dose-rate measured with the remote monitoring system Disassembly of the reusable items from the 150µSv/h 9µSv/h Transfer of the to the Fuel 150µSv/h 30µSv/h 6µSv/h 18µSv/h Storage of the old vessel head in the Fuel RP team 8 ALARA Technicians + 2 RP coordinators (inside/outside containment) + 4 RP for teledosimetry control + RP managers

15 PHASE 1 Disassembly of the reusable items from the Remote monitoring system: Accumulated Maximum dose dose (µsv) rate (µsv/h) Crane Crane Transfer of the to the Fuel Storage of the old vessel head in the Fuel

16 PHASE 1 Disassembly of the reusable items from the Transfer of the to the Fuel Storage of the old vessel head in the Fuel

17 PHASE 1 Disassembly of the reusable items from the May October 2015 Forbidden access to the Shielding to reduce the radiological impact in outer areas Work-management: minimization of jobs in the influenced area of the Fuel Temporal change of the affected area monitors threshold Transfer of the to the Fuel Storage of the old vessel head in the Fuel

18 PHASE 2 CRDM disassembling and conditioning in the Fuel Man hours Man msv Activity Inverted Estimated Received Scaffolding ,988 CRDM cutting ,161 Decontam ,7 2,787 Shielding 47 1,5 2,283 Transport of the and the CRDM to the Waste Storage

19 PHASE 2 CDRM disassembly and conditioning in the Fuel Activity Transfer to the Waste Storage Waste Man hours Man msv Inverted Estimated Re-estimated Received , ,388 Fuel Transport of the and the CRDM to the Waste Storage

20 PHASE 2 CDRM disassembly and conditioning in the Fuel RP team 4 ALARA Technicians + 1 RP coordinator + 2 RP for teledosimetry control + RP manager Transport of the and the CRDM to the Waste Storage Teledosimetry 16 remote monitoring DLD + 3 additional transmitters 1 personal computer 6 TLD

21 PHASE 2 RP checkpoints (entrance to the restricted area) Maximum dose-rate measured with the remote monitoring system CDRM disassembly and conditioning in the Fuel 3µSv/h 6µSv/h Fuel Transport of the and the CRDM to the Waste Storage 48µSv/h 41µSv/h Waste 58µSv/h 104 µsv/h

22 PHASE 2 CDRM disassembly and conditioning in the Fuel Remote monitoring system: Accumulated Maximum dose dose (µsv) rate (µsv/h) Driver Driver Transport of the and the CRDM to the Waste Storage 12 hours for the head vessel movement - saturday

23 PHASE 2 2 days /12 hours per day for the CRDM containers movement CDRM disassembly and conditioning in the Fuel Transport of the and the CRDM to the Waste Storage Final disposal

24 PHASE 1 and 2 Contamination control surveillance after each movement Transfer of the to the Fuel Transport of the and the CRDM to the Waste Storage Zero personal skin contamination events

25 4. Dose Results Summary Activity Man hours Man msv Inverted Estimated Re-estimated Received Assembly of the reusable items ,271 Disassembly of the old vessel head and auxiliary activities Preparation and transference of the old vessel head to the Fuel Assembly of the reusable items on the new head CDRM disassembling and conditioning in the Fuel Transfer to the Waste Storage , , , ,2-24, ,9-15,388 Plant modifications ,65 9,95 6,515 TOTAL ,75 164,05 119,842 25

26 5. Information and procedures Before - 2 reports describing specific RP activities: to the regulatory body - Emission of specific RP procedure describing the preparation and radiological control of the vessel head cover during transport - Presentation to the ALARA Committee (dose estimation and main RP activities) - Information to the entire organization (areas with forbidden access) After - 2 reports summarizing the obtained results: to the regulatory body - 2 reports with the remote monitoring system results - Presentation to the ALARA Committee (dose results and main RP activities) - Information to the entire organization 26

27 6. Learned lessons Dose planning RP involvement Specific procedures Effective communication Good ALARA performance Shielding Contamination control Remote monitoring 27

28 THANKS SEABED CHARACTERISATION TECNOAMBIENTE