Steam Generator Project Outage ALARA Report
Braidwood Generating Station
A1R12
Steam Generator Project Outage ALARA Report
Braidwood Generating Station
A1R12
Prepared By
Gary T. Infield
Michael Saunders
Steam Generator Project ALARA Engineers
Spring 2006
Table of Contents
Page
I. Introduction
Summary 3
Pre-Outage ALARA 3
Outage Craft Staffing 3
Primary Steam Generator Inspections 5
Secondary Steam Generator Inspections 65
II. Exposure Analysis 6
Pre-Outage Exposure 6
Hydrogen Peroxide Addition 6
Personnel Contamination Events 6
Estimated vs. Actual Exposure 7
Remote Monitoring Facility (RMF) 9
III. Lessons Learned / RWP ALARA Reviews 10
General Lessons Learned / Recommendations 10
Outage Daily Report 11
S/G Radiation Protection Support 12
Equipment Staging and Demob 14
S/G Platform / Bullpen Setup and Teardown; Decon Activities 15
Manways / Diaphragms Removal and Installation 17
Nozzle Cover Installation / Removal 19
Eddy Current Inspections 21
Secondary Side Closures 22
Sludge Lance Activities 23
FOSAR Activities 24
Supervisory Walkdowns 26
S/G Bowl Drains 27
I. INTRODUCTION
Summary
Westinghouse provided steam generator (S/G) inspection and repair services for Braidwood Station’s A1R12 Refueling Outage. The general scope for A1R12 primary side included eddy current inspections and tube repairs in all four S/Gs. The secondary side work scope included sludge lance, cleanliness inspection and FOSAR Activities in all four S/Gs. The A1R12 outage started April 16, 2006 and the S/G Project completed all containment work on April 29, 2006.
The original estimate for the S/G Project Team was 26.079 P-rem with a Stretch Goal of 23.471 P-rem. On the fourth day of the outage, the Basepoint and EPRI surveys were analyzed and the Estimate was reduced to 22.772 P-rem with a new Stretch Goal of 20.495 P-rem. The actual exposure was 27.625 P-rem. There was 4.921 P-rem of expanded scope. Excluding the expanded scope the actual exposure for the planned work scope was 22.704 or 99.7% of the Revised Estimate and 110.8% of the Revised Stretch Goal.
Pre-Outage ALARA
Westinghouse provided two ALARA Engineers, one for each shift. The two ALARA Engineers worked December 30, 2005 through January 13, 2006 at Westinghouse’s Waltz Mill site developing the S/G Project ALARA Estimate and the initial ALARA Plans per RP-AA-401. The Lead ALARA Engineer arrived on-site April 3, 2006 for the A1R12 Outage. The night shift ALARA Engineer arrived on site April 10, 2006.
The ALARA Engineers’ responsibilities during the outage were to:
- Interface between the Steam Generator Project and Braidwood Station in the execution of the RWP ALARA plans and outage S/G ALARA plan
- Coordinate exposure extensions and exposure issues
- Prepare Work in Progress Reports, ALARA Amendments and ALARA outage report
- Assist in mockup training
- Prepare and analyze dose reports on a shiftly basis during the outage
- Ensure proper dosimetry and respiratory protection is available for the appropriate S/G Project personnel
- Conduct pre-job ALARA briefs for all job evolutions
- Conduct observations and ensure the ALARA plans are implemented
The S/G Project Team ALARA estimates were presented to the Station ALARA Committee on April 10, 2006 and approved as presented contingent on two minor changes to the work scope.
Outage Staffing
Contractors provided to support the S/G Project activities included Radiation Protection Technicians (RPTs), Boilermakers, and Laborers. This report also includes the exposure information pertaining to these support groups.
All S/G primary platform workers that would access the platforms during the time from manway removal to manway installation were required to perform mockup training. The Westinghouse personnel received their training at Waltz Mill as well as on site. Craft and Radiation Protection personnel received their training on site. The S/G Radiation Protection Supervisor provided mockup training for the Laborers. In addition, mockup training was performed for installation and removal of the nozzle covers.
S/G Radiation Protection Support
Two Exelon RP Supervisors were provided to the S/G Project Team. The Braidwood RP Supervisor was committed to the S/G Project 1 week prior to the start of the outage. The second Exelon RP Supervisor arrived on site from Byron Station the night of the outage start. The late arrival of the Byron RP Supervisor created problems with pre-outage planning and discrepancies between the nightshift and dayshift communications the first few days of the outage. One example was the use of finger rings, not required at Braidwood but still required at the Byron. The RP Supervisor from Byron was not aware of this fact and assumed the rings were required as is the case at Byron.
The contract RPTs consisted of 2 Working Senior RPT Leads, 10 Senior RPTs, and 4 Junior RPTs for the two shifts. The Quad Cities outage hampered the arrival for the RPTs. In-processing for the contract RPTs occurred 5-6 days prior to the outage creating a conflict with the steam generator manway mockup training already in progress. Full dressout for the manway removal/installation started 5 days prior to the outage and required RPTs participation. The overall experience level of the contract Leads and Senior RPTs was high, with 83% having previous S/G Project RP support. The experience level was critical to the success of the outage.
S/G Boilermaker Craft
The Quad Cities outage hampered the scheduled arrival for the Boilermakers.
The impact of the late arrivals is discussed in the lessons learned for RWP 10005970.
Mockup training for manways/diaphragm removal and installation started 1½ weeks prior to the outage. Westinghouse provided two Subject Matter Experts for the manway and diaphragm removal/installation training. A secondary closure mockup was used for removal/installation of secondary closure training.
In addition, a full dressout mockup was required of the Boilermakers removing and installing the manways/diaphragms, with the Radiation Protection Technicians overseeing the evolutions.
During the period of eddy current inspections and repair, 3 S/G Project experienced Boilermakers were loaned to the S/G Project from Venture work on secondary plant systems to increase the experience level for manway/diaphragm installation. Just-In-Time training was performed for the Boilermakers at the mockup training facility. This training included hands-on diaphragm and manway installation for the crew.
S/G Labor Craft
The Laborers for the S/G Project consisted of a core of 10 Laborers (including Supervision). An additional 3 Laborers were added for platform teardown Overall the experience level of the Laborers for the project was high. Of the core 10 Laborers on the project, 90% had previous S/G Project experience in Unit 1 or Unit 2.
The Labor craft were trained in bullpen assembly, SuperVac assembly/disassembly, and proper S/G platform decon methods.
Nozzle Cover Installation / Removal Mockup Training
Extensive nozzle cover installation/removal mockup training was performed on Day 1 of the outage. Day and night shift jumpers trained together prior to breaking into shifts. Each jumper and platform worker was dressed out per the RWP requirements. The RPTs provided mockup RP support using video/audio and manual timekeeping. The proficiency standard used for the training was 30 seconds per jump. Actual mockup jumps ranged from 15 to 29 seconds. Mockup jumps included the nozzle covers with the new bowl drain plugs used as FME barriers. The bowl drain plugs had never been used at Braidwood and were designed to protect foreign material from entering the drain line. Also practiced was installing a modified nozzle cover with a pre-drilled hole so a 9” pipe extension could be inserted through the hole and attached to a hose in nozzle cover. The mockup of this included installing the nozzle cover, installing the pipe and attached hose. This modified nozzle cover was required to be installed in the 1A cold leg to draw any LSIV leak-by caused the scheduled work on the 1A loop drain valve, 1RC8040A.
Primary Steam Generator Inspections
Westinghouse performed in-service inspections of the primary side of all four-steam generators and made repairs as necessary with the use of mechanical plugs and stabilizers. This was accomplished using 8 ROSA robots with 16 manway mounted dual probe pushers and associated equipment.
The ALARA estimate for the eddy current inspections was based on the following work scope in all four-steam generators:
· 100% Bobbin
· 25% Top of Tubesheet
· Special Interest Examinations
The following repairs were performed for the primary side during the A1R12 outage:
S/G Tubes Plugged Tubes StabilizedStabilizers Installed
1A 11 11
1B 17 36 (stabilizers stacked)
1C 0 0
1D 0 0
28 47
Secondary Steam Generator Inspections
Sludge Lancing, Cleanliness Inspection and FOSAR (Foreign Object Search and Retrieval) were performed in all four-steam generators.
During sludge lancing, 184 lbs of sludge was collected. Following the sludge lancing, FOSAR identified 25 foreign objects. Successful retrieval or disposition was performed on all 25 foreign objects.
S/G Sludge Lbs. Foreign Objects Identified Foreign Objects Retrieved
1A 65.5 6 2
1B 38.5 11 5
1C 39.5 5 2
1D 40.5 3 3
II. EXPOSURE ANALYSIS
Pre Outage Exposure
Pre-outage estimated exposure was 0.030 P-rem and actual exposure was 0.022 P-rem. This included preparation work done in the CAF and the RWST cable run.
Hydrogen Peroxide Addition
The hydrogen peroxide addition started Day 0 at 1900, ~18 hours into the outage. The original projected Co58 peak was 4-5 uCi/gm with the actual peak at 2.3 uCi/gm.
Outage Co58 Peak
A1R12 2.3 uCi/gm
A1R11 10.4 uCi/ml
All S/G Project Team IMB containment work was stopped for the hydrogen peroxide addition and workers were out of IMB Day 0 by 1700 ~1 hour prior to hydrogen peroxide addition start. Work completed prior to the hydrogen peroxide addition included running cables and hoses through penetration 2PC074M and running the sludge lance/eddy current hoses/cables to 401’ OMB. Work in-progress was 1B/C platform setup and sludge lance/eddy current equipment move-in. The IMB was released Day 0 at 2300, ~6 hours after start of hydrogen peroxide addition.
Personnel Contamination Events
Following the recommendations from INPO, the procedure for Recognized Risk Personnel Contamination Event (RRPCE) was rewritten such that only by meeting very restrictive criteria could a RRPCE be considered. In past outages, RRPCEs averaged 11–22 per outage. In A1R12, 0 RRPCEs were submitted for pre-outage approval.
After ~6 PCEs the Radiation Protection Manager mandated all S/G team personnel wear a single set of PCs plus a second set of PCs or Cassies if working IMB or in stud cleaning tent. This presented another problem with heat stress concerns when the chillers were off.
Contamination became an issue in all of containment at ~Day 5 of the outage. Most workers were alarming at the PCMs and are losing their clothes. Some workers were waiting several hours to get out of the CAF. The problem was extremely low levels of Iodine-132 and noble gases originating from the refuel floor. The BUS outage was in effect and the chillers could not be turned on to dissipate the gases. Charcoal HEPAs were installed on various containment levels to reduce the Iodine-132. On Day 7, the chillers were turned back on and the workers were no longer alarming the PCMs due to this issue. Note that the in-plant Main Purge Ventilation was removed from service several years ago and is no longer available.
The key card for entering containment was located in the CAF before crossing the step-off pad. Several PCEs were suspected to be a result of workers unzipping their PCs, not removing their outer gloves and key carding out of the CAF. The step-off pad and PC doffing area were subsequently moved to an area before key carding out.
There were 84 PCEs for the Station, of which 15 were from the S/G personnel. Details Distribution of the S/G PCEs are as follows:
· The S/G Radiation Protection PCE occurred during the 1A/D EPRI survey. The survey was performed while the chillers were off resulting in PC sweat-through.
· The two PCEs for the Staging Equipment RWP occurred while replacing the tygon tubing during the 1C leak-by. Both were a result of water splashing on their skin.
· The one PCE for Platform/Bullpen was a result of deconning the 1C platform after the leak-by was stopped. During the decon, water splashed on the worker’s skin.
· Three of the seven PCEs for the Manways RWP were a result of poor rad worker practices. The remaining four were a result of PC sweat-through occurring while the chillers were off.
· The PCE for the Nozzle Cover RWP was determined to be a result of the S/G jumper’s plastics being torn.
· The three PCEs for the Eddy Current RWP occurred during ROSA installation and removal. Two of the three were a result of PC sweat-through and the other was a facial contamination determined to be “Unknown Cause”.
Estimated vs. Actual Exposure
The original estimate for the S/G Project Team was 26.079 P-rem with a Stretch Goal of 23.471 P-rem. On the fourth day of the outage, the Basepoint and EPRI surveys were analyzed and the Estimate was reduced to 22.772 P-rem with a new Stretch Goal of 20.495 P-rem. At project conclusion, the actual exposure was 27.625 P-rem including 4.921 P-rem of expanded scope. Excluding the expanded scope the actual exposure for the planned work scope was 22.704 or 99.7% of the Revised Estimate and 110.8% of the Revised Stretch Goal.
The original ALARA estimate approved by the Station ALARA Committee was based on actual exposure of A1R11 for the primary side and A1R10 for the secondary side. These exposures were then adjusted for work scope, exposure reduction initiatives, and anticipated dose rate differences. The S/G Project Team used the S/G Estimated Exposure Model to develop the estimate.
Following were the work scope differences between A1R11, A1R10 and the planned work scope for the A1R12 Outage:
· Reduction of work scope from A1R11 actual exposure:- A1R11 Eddy Current exposure adjustment (0.714) P-rem
(0.714) P-rem
· Additional work scope exposure for A1R12:
- A1R11 Nozzle Cover RWP exposure adjustment 0.432 P-rem
- FME plug installations 0.022 P-rem
- Increased A1R12 planned Bobbin Inspections (56% to 100%) 0.780 P-rem
- Increased A1R12 planned TTS Inspections (0% to 20%) 0.275 P-rem
- Increased base plate moves (1 to 3) 0.330 P-rem
- Secondary side Sludge Lance/FOSAR (0% to 100%) 3.507 P-rem
- Supervisory Walkdowns RWP exposure adjustment 0.282 P-rem
5.628 P-rem
Net Increase in Work Scope Exposure 4.914 P-rem
Following were the major exposure initiatives and adjustments that were incorporated into the A1R12 Outage: