IR 05000133/2006002
| ML061100212 | |
| Person / Time | |
|---|---|
| Site: | Humboldt Bay |
| Issue date: | 04/20/2006 |
| From: | Spitzberg D NRC/RGN-IV/DNMS/FCDB |
| To: | Keenan J Pacific Gas & Electric Co |
| References | |
| IR-06-002 | |
| Download: ML061100212 (16) | |
Text
April 20, 2006Mr. John Senior Vice President - Generation and Chief Nuclear Officer Pacific Gas and Electric Company PO Box 770000 Mail Code B32 San Francisco, California 94177-0001 SUBJECT:NRC INSPECTION REPORT 050-00133/06-002
Dear Mr. Keenan:
An NRC inspection was conducted on March 27-31, 2006, at your Humboldt Bay Power PlantUnit 3 facility. This inspection was an examination of activities conducted under your license asthey relate to safety and compliance of the Commission's rules and regulations and with the conditions of your license. Within these areas, the inspection included reviews of your maintenance, occupational radiation exposure, and radioactive waste treatment and effluentand environmental monitoring. On March 31, 2006, at the conclusion of the site visit, an exitbriefing was conducted with Mr. Roy Willis, Plant Manager, and other members of your staff. The enclosed report presents the scope and results of that inspection. The inspection determined that you were conducting decommissioning activities in compliance with regulatory and license requirements. In accordance with 10 CFR 2.390 of the NRC's "Rules of Practice," a copy of this letter, itsenclosure, and your response (if any) will be made available electronically for public inspectionin the NRC Public Document Room or from the NRC's document system (ADAMS), accessible from the NRC Web site at http://www.nrc.gov/reading-rm/Adams.html. To the extent possible,your response should not include any personal privacy, proprietary, or safeguards information so that it can be made available to the public without redaction. Should you have any questions concerning this inspection, please contact the undersigned at(817) 860-8191 or Emilio M. Garcia at (530) 756-3910.
Sincerely,
/RA/D. Blair Spitzberg, Ph.D., ChiefFuel Cycle and Decommissioning BranchDocket No.: 050-00133 License No.: DPR-7
Enclosure:
NRC Inspection Report 050-00133/06-002 Pacific Gas and Electric Company - 2 -
REGION IV Docket No.:050-00133License No.:DPR-7 Report No.:050-00133/06-002 Licensee:Pacific Gas and Electric Company (PG&E)
Facility:Humboldt Bay Power Plant (HBPP), Unit 3Location:1000 King Salmon AvenueEureka, California 95503Dates:March 27-31, 2006 Inspectors:Emilio M. Garcia, Health Physicist, Approved By:D. Blair Spitzberg, Ph.D., ChiefFuel Cycle and Decommissioning BranchAttachments:1) Supplemental Inspection Information2) Partial List of Documents ReviewedADAMS Entry:IR 05000133-06-02, on 03/27-31/06; Pacific Gas & Electric Co.;Humboldt Bay, Unit 3. No violations.
-2-EXECUTIVE SUMMARYHumboldt Bay Power Plant, Unit 3NRC Inspection Report 050-00133/06-002The Humboldt Bay Power Plant (HBPP), Unit 3 was shutdown in 1976. The facility has been ina SAFSTOR status since shutdown with minimal decommissioning activity. Maintenance and Surveillance*The licensee successfully completed a project to remove contaminated resin from theOff-gas Pipe Tunnel, an enclosed underground concrete tunnel. The resin had spilledfrom a broken pipe in the tunnel. The tunnel had contained the spilled resin. Thelicensee also removed the resin from the remainder of the pipes and from the Spent Fuel Pool (SFP) Demineralizer tank. Licensee personnel worked carefully and safely to adhere to procedural requirements (Section 1). Occupational Radiation Exposure*The licensee had developed a comprehensive, special radiation work permit to controlthe work related to the Off-gas Pipe Tunnel resin cleanup and SFP Demineralizer resin flush. The inspector concluded that overall the licensee had effectively limited the radiation exposure to personnel while recovering and containing a significant source of radiation (Section 2).Radioactive Waste Treatment and Effluent and Environmental Monitoring*There had been no detectable tritium in monitoring wells since January 2001. Thehistorical values detected in 1980's and 1990's were a fraction of the USEPA drinking water standard. There are no drinking water wells or other sources hydrologically down gradient from the site. Tritium or other radionuclide contamination of drinking water was not a problem at this site (Section 4.1).*The 2005 Annual Radioactive Effluent Release Report was submitted on a timely basisand met applicable regulatory requirements. The report documented that the releasesof radioactivity in gaseous and liquid effluents in 2005 did not exceed applicable regulatory limits (Section 4.2).
-3-Report DetailsSummary of Plant StatusHumboldt Bay Power Plant, Unit 3, is currently in decommissioning SAFSTOR status. Unit 3received an operating license from the Atomic Energy Commission on August 28, 1962. On July 2, 1976, Unit 3 was shutdown for annual refueling and seismic modifications. This work was suspended in December 1980 and in June 1983, then PG&E announced its intention to decommission the unit. Unit 3 has been essentially in SAFSTOR since July 1985. On July 19, 1988, NRC approved the licensee's SAFSTOR plan and amended the license to apossess-but-not-operate status. The license will expire on November 9, 2015. The facility hasundergone minimal decommissioning activity since shutdown. 1.0 Maintenance and Surveillance (IP 62801) a. Inspection ScopeThe inspector reviewed the licensee's preparations and conduct of the off Gas PipeTunnel resin cleanup and spent fuel pool (SFP) demineralizer flush project. b.Observations and FindingsDuring the spring of 2005, the licensee determined that the demineralizer resin used tomaintain the SFP water quality was approaching its useful life and needed to be replaced. When attempting to slurry the used resin from the SFP demineralizer tank to the resin disposal tank the transfer pipe became plugged. The licensee determined thatthe presence of fine particulates that collected in the SFP demineralizer tank were a significant contributor to the pipe plugging. These fine particulates resulted from the increased work in the SFP during 2004 and 2005 and had not been present in this quantity during previous resin removals. Several means to unplug the resin transfer pipe were attempted with no success. Finally, on August 5, 2005, the licensee installed a manifold on the demineralizer system to permit the use of pressurized water from the plant fire protection system. The fire protection system water can reach a pressure of 150 pounds per square inch gauge (psig). When the 150 psig water pressure was applied to this system the resin started to move,but soon a gasket failed and some resin spilled into the SFP demineralizer room. Thelicensee stopped work in this project, initiated cleanup of the SFP demineralizer room and begun to evaluate means of removing the remaining resin from SFP demineralizer, thus putting the transfer pipe back in service. Increases in radioactivity in the Liquid Radioactive Waste Receiver Tank and theTurbine Building Drain Tank lead the licensee staff to identify that the resin transfer pipe had also failed inside the Off-Gas Pipe Tunnel. The Off-Gas Pipe Tunnel is an L-shaped underground concrete tunnel leading from the plant vent, going partially under the fuel handling building and ending in the plant yard near the staircase to the +27-foot level. The Off-Gas Pipe Tunnel contained a number of pipes, including the resin transfer pipe.
-4-On February 8, 2006, the licensee staff performed and entry into the Off-Gas PipeTunnel and found approximately 2 to 4 cubic feet of resin. The resin spilled into theOff-Gas Pipe Tunnel from a break in the resin transfer pipe. This pipe was observed to be severely corroded. The corrosion was due to intruding ground water dripping on the pipe from cracks in the ceiling of the Off-Gas Pipe Tunnel. The licensee believes thatthe corroded pipe could not withstand the increased pressure of the fire system waterand that was why it failed. Radiation levels measured on contact with the resin transfer pipe suggested the presence of resin in the entire pipe before and after the pipe break.The licensee developed a plan of action to collect the spilled resin, clear the pluggedpipes, and empty the demineralizer tank of the used resin. To achieve these goals thelicensee:*Designated a senior experienced radiation protection professional to lead theproject.*Brought additional trained personnel from another licensee operated nuclearreactor site to supplement the onsite personnel.*Arranged for a contractor to provide pumps and resin receiver tank or storagevessel for collecting the contaminated resin, and an in-pool demineralizer to replace the disabled one.*Developed a specific procedure and permits for the work to be performed.
Prior to the initiation of cleanup work, two preliminary entries into the Off-gas Pipe weremade. These entries were to collect additional data needed for the project, to place a video camera for remote observation of conditions in the vault during the various aspects of the project, and to evaluate the condition of the tunnel.Examination of the video collected during these entries lead a licensee's specialist inconcrete to conclude that the leaks into the tunnel were mostly at the construction joints at the ceiling and the top two feet of the walls. There were no circumferential cracks.This specialist concluded that the tunnel was structurally sound. A licensee specialist on hydrology concluded that the surrounding groundwater had a higher piezometric level, or head, than the tunnel so the potential is for water to flow slowly into the tunnel andnot out of the tunnel. The licensee concluded that the Off-gas Pipe Tunnel hadcontained the spilled resin.The inspector reviewed the original, and revisions 1 and 2 of Temporary Procedure (TP)2006-03, Off-gas Pipe Tunnel Resin Cleanup and SFP Demineralizer Resin Flush. This was the principal procedure for this project. This procedure identified five phases for the cleanup as follow: 1) removal of large debris from tunnel and installation of a protective standpipe on the tunnel drain; 2) clearing the resin from the transfer pipes; 3) setting up the resin receiver tank or storage vessel and its associated shielding; 4) transferring of the resin from the Off-Gas Pipe Tunnel to the resin receiver tank; and 5) transferring the-5-resin in the condensate demineralizer room and SFP demineralizer, and associatedpiping, to the resin receiver tank. For each of these phases an Appendix to the procedure had been developed.The inspector observed several of the pre-job briefings conducted prior to each day'swork. These briefings described the goals for the day, job prerequisites, and individuals'
responsibilities. The participants on these pre-job briefings were attentive and theyasked questions and requested clarifications. During these pre-job briefings, a Job Safety Analysis and special (radiation) work permit (SWP) briefings were also conducted. During the pre-job briefing conducted on March 28, the inspector observed that thebriefing referred to Appendix 8.1 of the procedure, which addressed the removal of large debris from the pipe tunnel and installation of a protective standpipe on the tunnel drain. However, one of the goals discussed was cutting into the resin drain pipe. Cutting into the resin transfer pipe was not in Appendix 8.1 but was in Appendix 8.3. When theinspector brought this discrepancy to the Project Manager's attention the work did not proceed until additional flexibility was written into the temporary procedure.The inspector observed successful completion of the first four phases of the temporaryprocedure. Subsequent to the site visit, the licensee informed the inspector that phasefive had also been successfully completed. The inspector noted that although the project had experienced a number of delays due to minor problems, the licensee personnel worked carefully, safely, and adhered to procedural requirements. c.ConclusionsThe licensee successfully completed a project to remove contaminated resin from theOff-gas Pipe Tunnel, an enclosed underground concrete tunnel. The resin had spilledfrom a broken pipe in the tunnel. The tunnel had contained the spilled resin. Thelicensee also removed the resin from the remainder of the pipes and from the Spent Fuel Pool Demineralizer tank. Licensee personnel worked carefully, safely, and adhered to procedural requirements.
2.0Occupational Radiation Exposure (IP 83750) a. Inspection ScopeThe inspector reviewed the licensee's radiation protection preparations and practices insupport of the Off-gas Pipe Tunnel resin cleanup and SFP Demineralizer resin flush. b.Observations and FindingsAs described in Section 1 above, the licensee needed to cleanup a spill of contaminatedresin from the Off-gas Pipe Tunnel and remove the remaining resin from SFP Demineralizer tank and associated pipes. The resin had been used for maintaining the water quality of SFP. The resin had not only removed dissolved contaminants but had also entrapped fine particles present in the SFP water. Some of these particles were-6-special nuclear material waste from damaged fuel. During the initial entry into the Off-gas Pipe Tunnel, contact radiation dose rates with the resin pile was measured at 4,000 millirem per hour. The inspector reviewed the SWP 2006-0112, that the licensee had prepared for this job. The SWP identified three tasks: 1) area setup with no high-high radiation area entriesand no off-gas tunnel entry; 2) SFP Demineralizer vault work including setup, resin transfer, and tear down; and 3) Off-gas Pipe Tunnel work and resin transfer from the Off-gas Pipe Tunnel.The SWP specified dosimetry, respiratory protection, protective clothing, and detailedworker instructions. Dosimetry included not only the normally assigned thermo-luminescence dosimeter (TLD) and electronic dosimeter but additional TLD dosimeters at ankles and wrists, as well as lapel air samplers. The SWP also required continuous air monitors or general area air samples on access points. Respiratory protection was provided by pressurized air power respirators when working with open sources. The protective clothing not only included the normal cloth coveralls, cloth hood, integralbooties, and disposable rubber gloves but also included rubber boots and plastic suits when working in the Off-gas Pipe Tunnel.Additional radiological safety was provided by requiring verification of the operation ofthe plant ventilation system, continuous attendance of a radiation protection technicianwhen entering high or high-high radiation areas, and the operation of the high efficiency particulate absorbers (HEPA) ventilation system for at least 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> prior to entry intothe Off-gas Pipe Tunnel. There were additional radiation protection technicians at the access and egress points to assist with removal of protective clothing. Sea-vans had been placed over each of the access points into the Off-gas Pipe Tunnel. These structures provide improved protection from the environment and easier access, and could be locked to assure control into the high-high radiation area. Time keeping was used during entries into the Off-gas Pipe Tunnel to calculate DAC-hours based on lapel air sampler data.An as low as reasonably achievable (ALARA) review and job planning had beenperformed and an estimate of 1.1985 person-rem had been projected for the SWP with an ALARA goal of 1.0 person-rem. Subsequent to the site visit, the licensee provided the inspector with their dose estimates based on electronic dosimeter readings. Workers on this SWP had received a commutative dose of 1.266 person-rem. TLD results were expected to be consistent with these numbers. This value was approximately 6 percent above the projected dose. The Radiation Protection Manager stated that this increasein the commutative dose was due to an expanded scope of work.The inspector observed significant portions of the entry into the Off-gas Pipe Tunnel andthe SFP Demineralizer Vault. The inspector did not observe any instance where the requirements of the SWP were not followed.Two individuals were assigned additional dose to the skin of the whole body due to skincontamination. One individual received an 0.058 rad skin dose due to a cut on his plastic suit at the knee. This skin contamination occurred as the result of his plastic suit-7-tearing while crawling under some piping. It occurred during one of preparatory entriesand the licensee added knee pads to the outfits to prevent recurrence. The licensee also opened an alternate south access to the Off-gas Pipe Tunnel to facilitate some ofthe entries. The other individual was assigned 0.023 rad to the skin of the whole body.
This skin contamination appeared to have occurred during the removal of his protective clothing, but the licensee conservatively calculated the dose based on the entire time inthe tunnel.Two individuals had positive whole body counts following the work so the licensee hadthem collect their excretions for in-vitro bioassay for further evaluation. The in-vitro samples indicated that one individual was not internally contaminated. For the otherindividual, the in-vitro bioassay identified a small amount of internal contamination. The licensee was continuing to evaluate this data however, the Radiation Protection Manager stated that he expected that the committed effective dose equivalent would beless than 0.005 rem. The NRC will review the final results of this determination during afuture inspection. c.ConclusionsThe licensee had developed a comprehensive special radiation work permit to controlthe work related to the Off-gas Pipe Tunnel resin cleanup and SFP Demineralizer resin flush. The inspector concluded that overall the licensee had effectively limited the radiation exposure to personnel while recovering and containing a significant source of radiation.4.0Radioactive Waste Treatment and Effluent and Environmental Monitoring (84750)
4.1Review of Inadvertent Releases of Radioactive Liquids to Groundwater a.Inspection ScopeThe inspector reviewed historical and current status of tritium releases to groundwater. b.Observations and FindingsNRC Inspection reports 50-133/1997-002, 50-133/1998-01, 50-133/1998-03,50-133/2000-01, and 50-133/2000-02 document tritium presence in two monitoring wells located onsite.Table 2-8 of SAFSTOR Offsite Dose Calculation Manual (ODCM) specifies a reportinglevel for tritium of 20,000 picocuries per liter (pCi/l) in environmental samples. This value is based on the U. S. Environmental Protection Agency (USEPA) drinking water standard as listed in 40 CFR 141. If no drinking water pathway exits, the ODCM permits a reporting value of 30,000 pCi/l. The licensee, over the years, had used several different lower limits of detection (LLDs) for their analysis of tritium in groundwater samples. The LLD had ranged from 400 to 3000 pCi/l. The hydrological gradient of the-8-plant site is inclined toward Humboldt Bay and there are no drinking water wells downgradient from the plant site registered with the County of Humboldt, California. The closest drinking water well to the site is a Humboldt Community Services District Well approximately 0.4 miles away and up gradient from the site.During its operating period 1963 through 1976, the site experienced a number of onsitespills that included tritium. Tritium had been historically detected in quarterly samplesfrom monitoring well MW-11. The highest level was 7600 pCi/l detected in January 1985. Tritium levels at this well dropped until they were below the minimum detectablelevel of 500 pCi/l in the August 1997. An extensive evaluation was completed in 1999 which reviewed the historical site activities that could have resulted in tritium being released. A french drain that ran under the railroad track from Unit 3 to a location near well MW-11 was found to have 3,190 pCi/l of tritium in 1997. The 1974 spill ofcontaminated water from the condensate demin room, which overflowed into the Unit 3 yard, was the most probable explanation of the tritium detected in well MW-11. Of the six monitoring wells, only one other well has had any detectable tritium. This was well MW-1 which, from August 1997 to January 2001, had occasional readings near the LLD.
These positive results ranged from 405 to 589 pCi/l. All six site monitoring wells showed no tritium or other radionuclides above minimal detectable levels in the last 5 years. c.ConclusionsThere had been no detectable tritium in monitoring wells since January 2001. Thehistorical values detected in 1980's and 1990's were a fraction of the USEPA drinking water standard. There are no drinking water wells or other sources hydrologically down gradient from the site. Tritium or other radionuclide contamination of drinking water was not a problem at this site.
4.2Annual Radioactive Effluent Release Report for 2005 a.Inspection ScopeThe 2005 Annual Radioactive Effluent Release Report was reviewed. b.Observations and FindingsTechnical Specification 5.7.3 required that an Annual Radioactive Effluent ReleaseReport be submitted prior to April 1 of each year. In accordance with 10 CFR 50.36(a),
the report must cover the activities of the previous calender year. On March 29, 2005, the licensee submitted the 2005 Annual Radioactive Effluent Release Report on a timely basis. The report included summaries of radioactive gaseous and liquid releases from the site. The report concluded that the releases of radioactivity in gaseous and liquid effluents were well below the 10 CFR 50 Appendix I numerical ALARA guidelines and that the maximum potential direct radiation dose was well below the limits of10 CFR 20.1302(b)(2(ii).
-9-There were no abnormal gaseous or liquid releases during 2005. There were nine liquidbatch releases during 2005 and no continuous liquid releases. There were no batch gaseous releases during 2005. In 2005, there were no shipments of solid waste made.
The report included the latest revision to the ODCM, as required by TechnicalSpecification 5.6.1c.3. c.ConclusionsThe 2005 Annual Radioactive Effluent Release Report was submitted on a timely basisand met applicable regulatory requirements. The report documented that the releasesof radioactivity in gaseous and liquid effluents in 2005 did not exceed applicable regulatory limits.5.0Follow-up (IP 92701) (Closed) IFI 50-133/0503-02 Review licensee's evaluation of August 3, 2005, SFPDemineralizer system gasket failure that resulted in spill of radiologically contaminated resin.As noted on Section 1 of this report the licensee had installed an in-pool demineralizerto replace the disabled SFP demineralizer. The in-pool demineralizer was declared operable on March 10, 2006. Training for this system was completed on March 13,2006. As of the time of the inspection, the associated design change notice andproblem report had not been closed but knowledgeable licensee personnel indicated that all required tasks had been successfully completed. This IFI is considered closed. 6.0Exit MeetingOn March 31, 2006, at the conclusion of the site visit, the inspectors presented to theplant manager and other licensee staff members, the preliminary results on areas inspected. The licensee did not identify as proprietary any information provided to, or reviewed by, the inspectors.
ATTACHMENT 1SUPPLEMENTAL INSPECTION INFORMATIONPARTIAL LIST OF PERSONS CONTACTEDJ. Albers, Radiation Protection ManagerM. Antony, Decontamination Technician J. Brimble, Maintenance Supervisor J. Chadwick, Radiation Protection Engineer J. Davis, Radiation Protection Engineer J. Galle, Senior Engineer R. Grey, Spent Fuel Pool Demineralizer Resin Project Manager M. Grossman, Operations Supervisor V. Jensen, Quality Control Supervisor J. Mason, Quality Assurance Supervisor G. McKinnon, Control Operator R. Parker, Senior Radiation Protection Engineer L. Pulley, ISFSI Project Manager J. Rasmussen, Certified Fuel Handler M. Stich, ECP Lead Investigator - Diablo Canyon M. Smith, Engineering Manager D. Sokolsky, Supervisor of LicensingR. Sorensen, Programs Coordinator R. Willis, Plant M anagerINSPECTION PROCEDURES USEDIP 62801Maintenance and SurveillanceIP 71801 Decommissioning Performance and Status ReviewITEMS OPENED, CLOSED, AND DISCUSSED Opened NoneClosed50-133/0503-02IFIReview licensee's evaluation of August 3, 2005, SFPDemineralizer system gasket failure that resulted in spill of radiologically contaminated resin.Discussed None-2-LIST OF ACRONYMSALARA As Low As Reasonably AchievableCFRCode of Federal Regulations DAC Derived Air Concentration dpm/100 cm 2 Disintegrations per Minute per 100 cm 2HEPA High Efficiency Particulate Absorbers IFIInspection Followup Item IPInspection Procedure LLD Lower Limit of Detection MW Monitoring Well ODCM Offsite Dose Calculation Manual pCi/l picocuries per liter psig pounds per square inch gauge SFPSpent Fuel Pool SWP Special (radiation) Work Permit TLD Thermo-Luminescence Dosimeter TP Temporary Procedure USEPAUnited States Environmental Protection Agency ATTACHMENT 2PARTIAL LIST OF DOCUMENTS REVIEWED*Humboldt Bay Temporary Procedure 2006-03, Off-gas Pipe Tunnel Resin Cleanup andSFP Demineralizer Resin Flush, revision 0, effective March 26, 2006.*Humboldt Bay Temporary Procedure 2006-03, Off-gas Pipe Tunnel Resin Cleanup andSFP Demineralizer Resin Flush, revision 1, effective March 28, 2006 @ 1730.*Humboldt Bay Temporary Procedure 2006-03, Off-gas Pipe Tunnel Resin Cleanup andSFP Demineralizer Resin Flush, revision 2, effective March 29, 2006 @ 1100.*HBPP Radiation Work Permit 2006-0112, Resin Transfer, Revision 0, effective 03/21/2006.*Default Pre-Job Airborne Assessment, in support of HBPP Radiation Work Permit2006-0112, March 24, 2006.*ALARA Review and Job Planning Form, SWP/RWP 2006-0112, Flush resin from theOff-gas Tunnel and transfer resin from the SFP Demin to a receiver tank.*PG&E Letter HBL-06-006, Annual Radioactive Effluent Release Report for 2005,March 29, 2006.*SAPN 1234343, Unable to sluice SFP Demin resin to RDT, as of March 31, 2006.