ML033230052

November 2003 Davis-Besse Monthly Status Report

ML033230052
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Site:	Davis Besse
Issue date:	11/18/2003
From:	NRC/RGN-III
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Download: ML033230052 (7)

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November 2003 This is the fifteenth periodic update on the NRC response to the reactor vessel head damage at the Davis-Besse Nuclear Power Station. The updates will be available at public meetings of the NRC Davis-Besse Oversight Panel which is coordinating the agencys activities related to the damage. Each update will include background information to assist the reader in understanding issues associated with the corrosion damage.

High Pressure Pump Modifications and Testing Underway During a public meeting held on October 21 at the NRC headquarters in Rockville, Maryland, FirstEnergy officials presented the technical plans for modifying the high pressure injection pumps. An earlier engineering review by the company found that the pumps could malfunction under certain accident conditions.

In a pipe break or other loss of coolant accident, the high pressure injection pumps would pump water into Ongoing and Planned NRC the reactor cooling system while pressure remained Inspections high. Other emergency cooling systems would start once pressure in the reactor cooling system was The NRC has a series of inspections underway lowered. and planned before any decision on whether or not the Davis-Besse plant may resume operations:

Both pumps were shipped offsite for modification.

Work has been completed on one pump, and it has Ongoing - Management and Human been returned to the plant; the second pump is still Performance, Phase III (Safety Culture) -

undergoing modifications. This inspection focuses on FENOCs actions to improve management Both pumps must be installed and tested before the effectiveness and human performance and possible restart of the plant. NRC inspectors are its processes to survey and assess the monitoring the utilitys modification and testing of the safety culture among the staff at Davis-pumps. Besse -- how the management and workers will identify and deal with safety concerns.

NRCs Safety Culture Inspection Planned - Engineering and Maintenance Continues Backlog Review - This inspection will review work which FirstEnergy plans to complete An NRC inspection team is continuing its review of after possible restart of the plant to FirstEnergys efforts to evaluate and improve the determine if the utility has properly safety culture at the Davis-Besse plant. This review characterized and evaluated the work items includes the utilitys program to foster a "safety which will be deferred.

conscious work environment" in which workers feel free to raise safety issues without fear of retaliation. Planned - Restart Readiness Assessment Team - As the utility nears the point where The remaining inspection activities are (1) review of a it will seek NRC authorization for restart, recently completed FirstEnergy survey of employee this team inspection will thoroughly review attitudes toward safety and a safety conscious work the readiness of the plant and the plant envrionment; (2) observation of the activities of the staff to resume plant operations safely and plants Safety Conscious Work Environment Review in compliance with NRC requirements.

Team; and (3) review of FirstEnergys plan for long-

NRC Update: Davis-Besse Reactor Vessel Head Damage November 2003 - Page 2 term improvement actions and assessment of plant staff safety culture. FirstEnergy is expected to present its long-term plans at Mail Call the December 3 meeting with the NRC Oversight Panel.

The NRC continues to receive The results of the NRCs safety culture inspection, once completed, letters and e-mails expressing will be presented in a public meeting prior to any decision by the interest and concern about Davis-agency on restart of the Davis-Besse plant. Besse -- now totaling several thousand.

No Leakage in Reactor Pressure Test The agency has begun sending The test of the Davis-Besse reactor coolant system in late responses to all individual letters September found no evidence of leakage from the reactor vessel, and e-mails sent in by interested either in the new reactor vessel head or the bottom of the reactor members of the public.

vessel where tubes carry reactor monitoring instrumentation. There was no evidence of significant leakage in other reactor cooling system components.

The reactor was not started up for the test. Heat generated by the cooling system pumps raised the pressure in the reactor and associated piping to approximately 2155 pounds per square inch -- the normal operating pressure -- and approximately 530 degrees Fahrenheit, which is near the normal operating temperature.

NRC inspectors observed the test and reviewed the inspections of the vessel and reactor cooling system components. The inspection report on technical aspects of the test will be issued by early December.

During test activities, two incidents occurred involving errors by the operating staff. NRC Inspection Reports Being Prepared During preparations for the test, about 1,000 The findings of each of these inspections will be gallons of water was expelled from a pressurized discussed during the November 12 public meeting.

core flood tank into another holding tank because plant operators failed to adequately monitor Report Pending - Corrective Action Team pressure in the reactor cooling system. Inspection - This inspection looked at the effectiveness of the corrective action After the test ended, another operational incident program at Davis-Besse -- how the utility occurred. Normal procedures required that one finds, evaluates, and fixes problems.

group of control rods be withdrawn from the reactor core while the reactor cooling system test was Report Pending - Reactor Cooling System conducted. Plant operators failed to properly Test (Normal Operating Pressure) - This control pressure conditions in the reactor cooling inspection monitored the plants test of the system, and a pressure variation led to the reactor vessel and associated piping to automatic insertion of that group of control rods. assure there are no leaks in the system as Since the reactor was already shut down at the well as reviewing the performance of the time, this incident had no safety consequences. plant staff.

Operator performance issues during the test will be h Report Pending - Completeness and covered in two inspection reports - one was issued Accuracy Review - This inspection evaluated October 30 (see following news item) and the other the findings of a FirstEnergy review of will be issued in December. documents previously submitted to the NRC to assure that the information submitted was FirstEnergy is expected to discuss its corrective complete and accurate.

actions for these operator issues during the November 12 meeting with the NRC Oversight Panel.

NRC Update: Davis-Besse Reactor Vessel Head Damage November 2003 - Page 3 NRC Issues Resident Inspectors Report On October 30, the NRC issued a resident inspectors report (Report No. 50-346/03-18) which included the results of six weeks of inspection by NRC resident inspectors. The report details six findings determined to be of very low safety significance: 1) discovery of loose material in the containment building after licensee management had performed a final closeout inspection of this area; 2) inadequate procedure for testing the response time of the auxiliary feedwater pump 3) failure of control room staff to adequately monitor and control reactor coolant system pressure during reactor coolant system heatup; 4) failure of the licensee to understand and address all significant factors for proper installation of unqualified relays in the Safety Features Actuation System; 5) absence of procedural guidance for the performance of an Immediate Action Maintenance (IAM) process used for performing immediate repairs necessary to ensure public safety without following preestablished procedures; 6) inappropriate authorization by operations management to perform the IAM process during adjustments on a turbine-driven auxiliary feedwater pump governor.

The inspection report is available on the NRCs web site: http://www.nrc.gov - select Davis-Besse under key topics and then select news and correspondence to view a list of Davis-Besse documents.

NRC Issues Report on DBs Safety System Review On October 21, the NRC issued a report (Report No. 50-346/03-03) which details the NRCs review of the licensees efforts to ensure that the plants safety significant structures, systems and components can adequately support safe and reliable plant operations. NRC inspectors concluded that Davis-Besses review of safety significant systems, structures and components was conducted in a thorough and methodical manner.

NRC inspectors concluded that plant personnel were successful in identifying a number of deficiencies that needed to be addressed in order to restore these systems to the required level of operation. Most significant deficiencies were found in vital systems such as service water, emergency cooling, diesel generator and electrical distribution.

The inspection team reviewed the program developed by NRC Inspector General Report plant personnel to resolve the identified issues. This program involved determining the extent of the deficiencies On October 17 the NRC Inspector General and resolving these deficiencies through the use of the issued a report on its review of the NRC's stations established corrective action program. NRC Oversight of Davis-Besse Boric Acid inspectors concluded that the extent of condition reviews Leakage and Corrosion During the April were performed adequately. 2000 Refueling Outage" The resolution of identified deficiencies through the plants The report is available on the NRCs web corrective action program was examined by another NRC site at:

inspection, the Corrective Action Team Inspection, and will be documented in a separate inspection report. http://www.nrc.gov/reading-rm/doc-collection s/insp-gen/2004/

Davis-Besse Restart Checklist The Oversight Panel has created a restart checklist categorizing 31 actions in seven major areas which FirstEnergy needs to complete before the NRC can consider making a decision on whether Davis-Besse may restart. The NRC oversight panel has determined that the utility has adequately completed 22 of those actions.

NRC inspections are directed at evaluating the checklist items as well as reviewing the ongoing work at Davis-Besse.

NRC Update: Davis-Besse Reactor Vessel Head Damage November 2003 - Page 4 The completed items are shown in italics and have a check mark in front of the item. For the completed items, the list also includes the inspection report which documents the NRCs review of the item.

1. Adequacy of Root Cause Determinations U 1.a Penetration Cracking and Reactor Pressure Vessel Corrosion (Report No. 50-346/03-04)

U 1.b Organizational, Programmatic and Human Performance Issues (Report No. 50-346/02-18)

2. Adequacy of Safety Significant Structures, Systems, and Components 2.a Reactor Pressure Vessel Head Replacement U 2.b Containment Vessel Restoration Following Reactor Pressure Vessel Head Replacement (Report No. 50-346/03-05) 2.c Structures, Systems, and Components Inside Containment U 2.c.1 Emergency Core Cooling System and Containment Spray System Sump (Report No. 50-346/03-17)

U 2.d Extent-of-Condition of Boric Acid in Systems Outside Containment (Report No. 50-346/03 to be issued) 2.e High Pressure Injection Pump Internal Clearance/Debris Resolution

3. Adequacy of Safety Significant Programs 3.a Corrective Action Program U 3.b Operating Experience Program (Report No. 50-346/03-09)

U 3.c Quality Audits and Self-Assessments of Programs (Report No. 50-346/03 to be issued)

U 3.d Boric Acid Corrosion Management Program (Report No. 50-346/03-17)

U 3.e Reactor Coolant System Unidentified Leakage Monitoring Program (Report No. 50-346/03-09)

U 3.f In-Service Inspection Program (Report No. 50-346/03-09)

U 3.g Modification Control Program (Report No. 50-346/03-09)

U 3.h Radiation Protection Program (Report No. 50-346/03-17)

U 3.i Process for Ensuring Completeness and Accuracy of Required Records and Submittals to the NRC - (Report No. 50-346/03 to be issued)

4. Adequacy of Organizational Effectiveness and Human Performance U 4.a Adequacy of Corrective Action Plan (Report No. 50-346/02-18) 4.b Effectiveness of Corrective Actions

5. Readiness for Restart U 5.a Review of Licensees Restart Action Plan (Report No. 50-346/03 to be issued) 5.b Systems Readiness for Restart 5.c Operations Readiness for Restart 5.d Test Program Development and Implementation

6. Licensing Issue Resolution (Not discussed in inspection reports)

U 6.a Verification that Relief Requests A8 and A12 regarding the Shell to Flange Weld (previously submitted by letter dated September 19, 2000) is not Impacted by the Midland RPV Head U 6.b American Society of Mechanical Engineers (ASME) Code Relief Request for Failure to Maintain Original Radiographic Tests of the Midland Head to Flange Weld (Planned Relief Request A26)

U 6.c ASME Code Relief Request for Inability to Radiographically Test 100% of the Midland Reactor Pressure Vessel Head to Flange Weld (Planned Relief Request A27)

U 6.d Resubmit Relief Request A2 (previously submitted by letter dated September 19, 2000) for ASME Code for Inability to Perform 100% volumetric and surface examination of Head to Flange Weld Next Davis-Besse NRC Oversight Panel Meetings 2 p.m. and 7 p.m., Wednesday, Dec. 3, Oak Harbor High School

NRC Update: Davis-Besse Reactor Vessel Head Damage November 2003 - Page 5 Restart Check List items - continued U 6.e Reconciliation Letter that Demonstrates How the New Reactor Pressure Vessel Head Correlates With the ASME Code and QA Index for Section III and Section XI - Commitments U 6.f Verification Letter of Technical Specification Pressure/Temperature Curves for New Vessel Head

- Commitment U 6.g Request to relocate High Pressure Injection and Low Pressure Injection Subsystems Flow Balance Testing from Technical Specifications 4.5.2.h to Updated Safety Analysis Report Technical Requirements Manual

7. Confirmatory Action Letter Resolution 7.a Verification that Confirmatory Action Letter Items are Resolved, Including a Public Meeting to Discuss Readiness for Restart Background Summary: What Happened at Davis-Besse In March 2002 plant workers discovered a cavity in the head or top of the reactor vessel while they were repairing control rod tubes which pass through the head. The tubes, which pass through the reactor vessel head, are called control rod drive mechanism nozzles. Cracks were detected in 5 of the 69 nozzles.

In three of those nozzles, the cracks were all the way through the nozzle, allowing leakage of reactor cooling water, which contains boric acid.

Corrosion, caused by the boric acid, damaged the vessel head next to Nozzle No. 3, creating an irregular cavity about 4 inches by 5 inches and approximately 6 inches deep. The cavity penetrated the carbon steel portion of the vessel head, leaving only the stainless steel lining. The liner thickness varies somewhat with a minimum design thickness of 1/8 inch. Subsequent examination by Framatome, FirstEnergys contractor, found evidence of a series of cracks in the liner, none of which was entirely through the liner wall.

After circumferential cracks - around the nozzle wall - were found in the control rod drive nozzles at Unit 3 of the Oconee Nuclear Power Station in 2001, the NRC required all pressurized water reactor (PWR) operators to report to the NRC on structural integrity of the nozzles and their plans to inspect the nozzles. Plants with similar operating history to Oconee Unit 3, including Davis-Besse, were to inspect their reactor vessel head penetrations by December 31, 2001, or to provide a basis for concluding that there were no cracked and leaking nozzles.

FirstEnergy Nuclear Operating Company requested an extension of the inspection deadline until its refueling outage beginning March 30, 2002, and provided the technical basis for its request. The NRC did not allow the plant to operate until March 30, but agreed to permit operation until February 16, provided that compensatory measures were taken to minimize possible crack growth during the time of operation. The NRC was unaware that nozzle leakage or corrosion had occurred at Davis-Besse when it agreed to the February 16 date.

Barriers Built into Nuclear Plants to Protect Public Health and Safety The design of every nuclear power plant includes a system of three barriers which separate the highly radioactive reactor fuel from the public and the environment. The Davis-Besse reactor head damage represented a significant reduction in

NRC Update: Davis-Besse Reactor Vessel Head Damage November 2003 - Page 6 the safety margin of one of these barriers, the reactor coolant system. The reactor coolant system, however, remained intact, as well as the other two barriers, the fuel and the containment.

1. Fuel Pellets and Rods The first barrier is the fuel itself. The fuel consists of strong, temperature-resistant ceramic pellets made of uranium-oxide. The pellets are about the size of a fingertip. They retain almost all of the highly radioactive products of the fission process within their structure.

The pellets are stacked in a rod made of a zirconium alloy. At Davis-Besse, each fuel rod is about 13 feet long.

The rods are assembled into bundles, with each assembly containing 208 rods. The reactor core contains 177 fuel assemblies. Any fission products which escape from the pellets are captured inside the cladding of the rod, which is designed to be leak-tight. Small pin hole leaks do occasionally occur, however, and the operating license requires leakage monitoring and contains limits on the maximum allowable leakage of radioactive materials from the fuel rods.

2. Reactor Coolant System The second barrier is the reactor coolant system pressure boundary. The reactor core is contained inside the reactor pressure vessel, which is a large steel container. Thick steel pipes supply cooling water to the reactor and carry away the heated water after it passes through the reactor core. The pressure vessel, the connected piping, and other connected components make up the reactor coolant system pressure boundary. At Davis-Besse, the reactor coolant system contains about 60,000 gallons of cooling water, circulated by four large pumps at a rate of about 360,000 gallons per minute.

This system is designed to be leak-tight at operating conditions which include a water temperature of 605E F and a water pressure of 2,150 pounds per square inch. The operating license contains limits on the maximum allowable amount of leakage from the system, and it specifies requirements for monitoring any leakage. If a leak is identified as being through any solid wall of the system (reactor vessel, cooling pipes or other components) continued operation of the plant is prohibited, no matter how small the leak rate.

3. Containment Building The third barrier is the containment building. This is a large cylindrical building which contains the entire reactor coolant system. None of the piping that contains the high-temperature and high-pressure reactor coolant water extends outside the containment building. The containment is a 1 1/2 inch thick steel cylinder, rounded at the top and bottom, which is designed to be leak-tight. This steel structure is surrounded by a reinforced concrete shield building, which is the round building visible from the outside of the plant. Its walls are 2 to 3 feet thick.

NRCs Response to Vessel Head Damage The NRC responded to the vessel head degradation with a series of actions, some specific to Davis-Besse and others aimed at other PWR plants. The agency directed all PWR licensees to report on the condition of their reactor heads and later specified more stringent examination for inspecting the reactor heads. The NRC also established a Lessons Learned Task Force to review the agencys activities associated with the Davis-Besse reactor head issue.

NRC Davis-Besse Oversight Panel An NRC Davis-Besse Oversight Panel was created in April 2002 to make sure that all corrective actions, required to ensure that Davis-Besse can operate safely, are taken before the plant is permitted to restart and that Davis-Besse maintains high safety and security standards if it resumes operations. Should the plant restart, the Oversight Panel will evaluate if Davis-Besses performance warrants reduction of the NRCs heightened oversight and, if so, recommend to NRC management that the plant return to a regular inspection schedule. The panel was established under the agencys Manual Chapter 0350.

NRC Update: Davis-Besse Reactor Vessel Head Damage November 2003 - Page 7 The panel brings together NRC management personnel and staff from the Region III office in Lisle, Illinois, the NRC Headquarters office in Rockville, Maryland and the NRC Resident Inspector Office at the Davis-Besse site. The eight-member panels chair and co-chair are John Grobe, a senior manager from Region III, and William Ruland, a senior manager from NRC headquarters.

The agency has supplemented the resident inspection staff with an additional resident inspector who began work at Davis Besse in September, bringing the total staff there to three.

Public Participation in the Process The NRCs experience is that members of the public, including public officials and citizens, often raise questions or provide insights that are important to consider. If you have questions or want to provide information or a point of view, please contact us. For feedback on this newsletter, contact Viktoria Mitlyng 630/829-9662 or Jan Strasma 630/829-9663 (toll free 800/522-3025 - ext -9662 or -9663). E-mail:

opa3@nrc.gov. Extensive information about the Davis-Besse reactor vessel head damage and the ensuing activities is available on the NRC web site: http://www.nrc.gov - select Davis-Besse under the list of key topics.