IR 05000237/2016008

NRC Design Bases Inspection (Team) Report 05000237/2016008; 05000249/2016008, February 8 � 12, 2016 and February 22 � 26, 2016 (Axd)

ML16098A255
Person / Time
Site:	Dresden
Issue date:	04/06/2016
From:	Dave Hills NRC/RGN-III/DRS/EB2
To:	Bryan Hanson Exelon Generation Co, Exelon Nuclear
References
IR 2016008
Download: ML16098A255 (22)

Text

April 6, 2016

SUBJECT:

DRESDEN NUCLEAR POWER STATION, UNITS 2 AND 3 - NRC DESIGN BASES INSPECTION (TEAM) INSPECTION REPORT 05000237/2016008; 05000249/2016008

Dear Mr. Hanson:

On February 26, 2016, the U.S. Nuclear Regulatory Commission (NRC) completed the team portion of the pilot Design Bases Inspection at your Dresden Nuclear Power Station, Units 2 and 3. The enclosed report documents the results of this inspection, which were discussed on February 26, 2016, with Mr. P. Karaba, and other members of your staff.

Based on the results of this inspection, the NRC inspectors did not identify any findings or violations of more than minor significance.

In accordance with Title 10 of the Code of Federal Regulations (10 CFR) 2.390, Public Inspections, Exemptions, Requests for Withholding, of the NRC's "Rules of Practice," a copy of this letter, its enclosure, and your response (if any) will be available electronically for public inspection in the NRCs Public Document Room or from the Publicly Available Records (PARS)

component of the NRC's Agencywide Documents Access and Management System (ADAMS).

ADAMS is accessible from the NRC Web site at http://www.nrc.gov/reading-rm/adams.html (the Public Electronic Reading Room).

Sincerely,

/RA/

David E. Hills, Acting Chief Engineering Branch 2 Division of Reactor Safety Docket Nos. 50-237, 50-249 License Nos. DPR-19; DPR-25

Enclosure:

IR 05000237/2016008; 05000249/2016008

REGION III==

Docket Nos:

05000237; 05000249 License Nos:

DPR-19; DPR-25 Report No:

05000237/2016008; 05000249/2016008 Licensee:

Exelon Generation Company, LLC Facility:

Dresden Nuclear Power Station, Units 2 and 3 Location:

Morris, IL Dates:

February 8 - 12, 2016 February 22 - 26, 2016 Inspectors:

A. Dunlop, Senior Engineering Inspector, Lead S. Sheldon, Senior Engineering Inspector, Electrical G. ODwyer, Engineering Inspector, Mechanical R. Baker, Operations Engineer S. Kobylarz, Electrical Contractor G. Gardner, Mechanical Contractor Observer:

N. Hansing, Engineering Inspector, NRO Approved by:

David E. Hills, Acting Chief Engineering Branch 2 Division of Reactor Safety

SUMMARY

Inspection Report 05000237/2016008; 05000249/2016008, 02/08/2016 - 02/26/2016; Dresden

Nuclear Power Station, Units 2 and 3; Pilot Design Bases Inspection (Team).

The inspection was a 2-week onsite baseline inspection that focused on the design of components. The inspection was conducted by regional engineering inspectors and two consultants. No findings of significance were identified by the inspectors. The NRC's program for overseeing the safe operation of commercial nuclear power reactors is described in NUREG-1649, Reactor Oversight Process, Revision 5, dated February 201

NRC-Identified

and Self-Revealed Findings No findings were identified during this inspection.

Licensee-Identified Violations

No findings were identified during this inspection.

REPORT DETAILS

1R21 Design Bases Inspection (Team)

.1 Introduction

The objective of the pilot Design Bases Inspection is to verify that design bases have been correctly implemented for the selected risk-significant components and that operating procedures and operator actions are consistent with design and licensing bases. As plants age, their design bases may be difficult to determine and an important design feature may be altered or disabled during a modification. The Probabilistic Risk Assessment model assumes the capability of safety systems and components to perform their intended safety function successfully. This inspectable area verifies aspects of the Initiating Events, Mitigating Systems, and Barrier Integrity cornerstones for which there are no indicators to measure performance.

Specific documents reviewed during the inspection are listed in the Attachment to the report.

.2 Inspection Sample Selection Process

The inspectors selected risk-significant components and operator actions for review using information contained in the licensees Probabilistic Risk Assessment and the Dresden Standardized Plant Analysis Risk Model. In general, the selection was based upon the components and operator actions having a risk achievement worth of greater than 1.3 and/or a risk reduction worth greater than 1.005. Based on this process, a number of risk-significant components, including those with Large Early Release Frequency implications, were selected for the inspection. The operator actions or operating procedures selected for review included actions taken by operators both inside and outside of the control room during postulated accident scenarios associated with the selected components. In addition, the inspectors selected operating experience issues associated with the selected components.

The inspectors performed a margin assessment and detailed review of the selected risk-significant components to verify that the design bases have been correctly implemented and maintained. This design margin assessment considered original design reductions caused by design modification, or power uprates, or reductions due to degraded material condition. Equipment reliability issues were also considered in the selection of components for detailed review. These included items such as performance test results, significant corrective action, repeated maintenance activities, Maintenance Rule (a)(1) status, components requiring an operability evaluation, system health reports, and U.S. Nuclear Regulatory Commission (NRC) resident inspector input of problem areas/equipment. Consideration was also given to the uniqueness and complexity of the design, operating experience, and the available defense in depth margins. A summary of the reviews performed and the specific inspection findings identified are included in the following sections of the report.

The inspectors also identified procedures and modifications for review that were associated with the selected components. In addition, the inspectors selected operating experience issues associated with the selected components.

This inspection constituted 13 samples (8 components, 2 components with Large Early Release Frequency implications, and 3 operating experience) as defined in Inspection Procedure 71111.21M-2.01.

.3 Component Design

a. Inspection Scope

The inspectors reviewed the Updated Final Safety Analysis Report (UFSAR), Technical Specifications (TS), design basis documents, drawings, calculations and other available design basis information, to determine the performance requirements of the selected components. The inspectors used applicable industry standards, such as the American Society of Mechanical Engineers Code, Institute of Electrical and Electronics Engineers Standards, and the National Electric Code, to evaluate acceptability of the systems design. The NRC also evaluated licensee actions, if any, taken in response to NRC issued operating experience, such as Bulletins, Generic Letters, Regulatory Issue Summaries, and Information Notices (INs). The review was to verify that the selected components would function as designed when required and support proper operation of the associated systems. The attributes that were needed for a component to perform its required function included process medium, energy sources, control systems, operator actions, and heat removal. The attributes to verify that the component condition and tested capability was consistent with the design bases and was appropriate may include installed configuration, system operation, detailed design, system testing, equipment and environmental qualification, equipment protection, component inputs and outputs, operating experience, and component degradation.

For each of the components selected, the inspectors reviewed the maintenance history, preventive maintenance activities, system health reports, operating experience-related information, vendor manuals, electrical and mechanical drawings, and licensee Corrective Action Program (CAP) documents. Field walkdowns were conducted for all accessible components to assess material condition, including age-related degradation and to verify that the as-built condition was consistent with the design. Other attributes reviewed are included as part of the scope for each individual component.

The following 10 components (samples) were reviewed:

Emergency Diesel Generator (EDG) 2 (2-6601): The inspectors reviewed EDG loading calculations focusing primarily on core spray pump loading. The EDG output breaker control logic, protective relaying, and control voltage were reviewed to verify adequate voltage would be available to close the output breaker when needed. The inspectors reviewed the licensee had analyzed equipment operation considering the voltage and frequency bounds identified in the TS. Surveillance procedures were reviewed to verify the adequacy of the licensees testing of the EDG initiation logic. The inspectors also reviewed completed TS surveillances including the endurance test to ensure that the loading test was conducted in accordance with the TS. The EDG operating and standby readiness procedures were reviewed to verify operations conformed to design requirements and complied with TS. The inspectors also reviewed the following EDG sub-components:

EDG 2 Air Start (2-4600): The inspectors reviewed the sizing of the air start receivers to verify system capacity to support the minimum number of required starts for the EDG. The inspectors reviewed EDG surveillances to verify that all various combinations of air start compressor and air filter alignment were properly tested. In addition, the modifications replacing the air start air filters and one air compressor were reviewed to verify the system design basis was maintained.

EDG 2 Jacket Water (2-6600): The inspectors examined the operational history, condition reports, and testing of the jacket water system to ensure it was capable to support EDG operations. Vendor manuals were reviewed to verify recommended operating limits were properly incorporated in station procedures.

Diesel Generator Cooling Water Pump (2-3903): The inspectors reviewed the system hydraulic calculations such as, net positive suction head, vortexing, and minimum required flow to ensure that the pump was capable of performing its safety function. The inspectors also reviewed the vendor manual for the pump to determine whether the pumps characteristics met the design basis requirements and these requirements were accurately incorporated in periodic testing of the pump. Inservice testing results were reviewed to assess potential component degradation and impact on design margins. Pump operation from various suction sources was reviewed to evaluate the pumps ability to provide the required flow from each source. The inspectors reviewed pump control logic, pump voltage requirements, thermal overload sizing, and voltage drop calculations to verify adequate voltage would be available to operate the pump when required. The inspectors reviewed the normal and abnormal operating procedures for the pump to verify operations conformed to design requirements and complied with TS.

EDG 2 Room Ventilation Fan (2-5790): The inspectors reviewed calculations addressing the room airflow required to maintain the EDG room below the maximum design basis temperature limit with the EDG at full load. Modifications and maintenance records, including the replacement of a damaged fan, were reviewed to verify correct components were used and post maintenance testing was adequate to verify operational readiness. Periodic testing and corrective action for the inlet, outlet, and temperature control ventilation dampers were reviewed to verify if TS requirement were satisfied. Corrective actions for out of specification ventilation flow readings were examined to verify the cause of the problem and actions were adequate to resolve the issue. Normal and abnormal operating procedures were reviewed to verify the procedures were properly updated after implementation of the modifications. The inspectors reviewed the supply fan maximum brake horsepower requirements to verify the adequacy of the motor capability to supply power during worse case design basis conditions.

The results of load flow and voltage regulation analyses were reviewed to assess the adequacy of motor starting and running during degraded offsite voltage conditions coincident with a postulated design basis accident. The inspectors reviewed the motor breaker settings to assess the adequacy of motor overcurrent protection during the most limiting design basis operating conditions. The EDG operating and standby readiness procedures were reviewed to verify operations of the EDG ventilation system operation conformed to functionality and design requirements. The inspectors also reviewed instrumentation used for the automatic operation of the room ventilation, including power supplies and setpoints to ensure proper system operation.

250 Volts Direct Current (VDC) Turbine Building Motor Control Center (MCC) #2 (2-83250-2): The inspectors reviewed the design basis loading calculations, breaker settings, and the available short circuit current at the MCC to assess the capability of the selected breakers to operate reliably during design basis conditions and to withstand limiting maximum short circuit conditions. The load flow and voltage analysis for the MCC was reviewed to verify the adequacy of voltage at selected components during limiting design basis conditions. The inspectors reviewed an engineering change that installed structural bracing to improve the capability of the MCC to withstand seismic forces. The applicable operating procedures for MCC 2 were reviewed to verity operations conformed to design requirements and complied with TS.

480 Volts Alternating Current (VAC) Switchgear Bus 29 (2-7329-2): The inspectors reviewed the load flow analysis short circuit calculation to verify breakers were adequately sized for interrupt capability. Bus supply transformer T29 replacement modification was reviewed to ensure design adequacy. The low pressure coolant injection swing bus cross-connect between MCC 29-7 and MCC 28-7 was reviewed to verify the automatic transfer on loss of Bus 29.

The inspectors also reviewed the time delay setpoint calculations, and recent surveillances to verify the transfer would occur within limits assumed in the loss-of-offsite-power/loss-of-coolant-accident (LOCA) accident analysis.

The inspectors reviewed the normal and abnormal operating procedures for the 480 VAC distribution system to verify operations conformed to design requirements and complied with TS.

Unit 2 Essential Service System Power Supply Inverter, Distribution Panel, and Automatic Transfer Switch (2-0902-49): The inspectors reviewed the calculations that determined the maximum loading on the inverter to assess the adequacy of the inverter capacity rating and the voltage supplied to the inverter from the station battery during design basis operating conditions. The breaker settings for the safety-related VDC power supplied to the inverter were reviewed to verify the adequacy of the selected trip settings. The inspectors also reviewed vendor test documentation to verify the capability of the inverter for reliably operation at maximum expected loading conditions. The essential service systems distribution panel loading and voltage drop analysis were reviewed to assess the adequacy of the available voltage during design basis operating conditions. The inspectors also reviewed an engineering change that incorporated vendor recommended capacitor replacements to ensure equipment reliability. The inspectors also observed control room operator actions and the plant safety-system response for a simulated design basis accident scenario at the plant control room simulator. Operating procedures applicable to the inverter power supply were reviewed to verify that periodic tests conformed to the TS requirements and industry standards. The inverter testing procedures were also reviewed to verify they conformed to the requirements for functionality of equipment that supports TS equipment operability.

2B Core Spray Pump (2-1401-2B): The inspectors reviewed the core spray pump and motor design basis including performance, net positive suction head, and electrical power requirements. The inspectors reviewed the function of the pump during postulated small and large break LOCAs including required minimum flow and runout limits. The emergency operating procedure associated with transferring the pump suction for post-LOCA operation from the torus to the condensate storage tank was reviewed. The inspectors also reviewed setpoints associated with the transfer of the pump suction from the torus to the condensate storage tank. Surveillance test procedures and recent test results were reviewed to verify acceptance criteria were appropriate and met, and performance degradation would be identified. The inspectors reviewed motor sizing, pump brake horsepower requirements, vendor ratings, and pump test data to ensure the pump and motor were sufficient for design basis load conditions. The load flow analysis was reviewed to determine the adequacy of voltage at motor terminals during degraded voltage conditions. The motor protective device coordination curves were reviewed to determine the adequacy of electrical protection. The inspectors also reviewed core spray initiation logic and associated surveillances to verify conformance with design and TS requirements.

2B Core Spray Pump Discharge Valve(2-1402-25B): The inspectors reviewed the motor-operated valve (MOV) calculations, including required thrust, weak link, voltage drop, and maximum differential pressure, to assess its capability to perform its functioning under design and licensing bases conditions. Inservice test results, including diagnostic testing, leak rate testing, valve exercising, and remote pushbutton control stations were reviewed to verify acceptance criteria were met and assess the licensees ability to detect performance degradation.

The inspectors also reviewed the maintenance activities associated with the MOVs remote push button station to ensure it was adequate to resolve a previous issue that prevented an MOV from operating when called upon. The inspectors reviewed the valve control logic to ensure design interlocks and permissive functioned as designed, and conformed to design requirements and operating procedures. This included reviewing calibration surveillances for the low pressure injection permissive. The inspectors reviewed thermal overload settings for adequacy considering the valves use as a throttle valve. The procedures used to throttle the core spray discharge valves when the injection system would be used to aid in long term control of reactor vessel level was reviewed to ensure the valve would continue to be able to perform its design functions in this mode of operation.

Unit 2 Reactor Building to Torus Vacuum Relief Valve (2-1601-20B): The inspectors reviewed the design basis of the air-operated vacuum relief valve including requirements for the valve to operate under postulated transient and accident conditions. This review included the capacity of the safety-related portion of the pneumatic supply system to operate the valve under the most limiting conditions. Surveillance test procedures, as well as the results of recent tests, were reviewed to verify acceptance criteria were met and performance degradation would be identified. The inspectors also reviewed the capability of the valve to operate under the most limiting temperature and pressure conditions.

The inspectors reviewed the vacuum relief valve pilot solenoid valve schematic diagrams for operational requirements and the environmental conditions required for the solenoid to operate during design basis events. The solenoid valve voltage rating was reviewed to assess operational capability during a postulated design basis accident.

Unit 2 Torus Vent and Purge Valve (2-1601-56): The inspectors reviewed the design basis of the air-operated torus vent and purge valve including requirements for the valve to operate under postulated transient and accident conditions. This review included the capacity of the safety-related portion of the pneumatic supply system to operate the valve under the most limiting conditions.

The inspectors reviewed surveillance test procedures, as well as the results of recent tests, to verify acceptance criteria were met and performance degradation would be identified. This included verifying testing of stroke times for primary containment isolation valves was consistent with design limits specified in the UFSAR and Technical Requirements Manual. The inspectors also reviewed the capability of the valve to operate under the most limiting temperature and pressure conditions. The inspectors reviewed the vent and purge valve pilot solenoid valve schematic diagrams for operational requirements and the environmental conditions required for the solenoid to operate during design basis events. The solenoid valve voltage rating was reviewed to assess operational capability during a postulated design basis accident. The inspectors reviewed the engineering change to upgrade the solenoid valve qualification requirements to environmental qualification level 1. The inspectors reviewed control logic and schematic diagrams to verify operation of valve conformed to design requirements and operating procedures.

b. Findings

No findings were identified.

.4 Operating Experience

a. Inspection Scope

The inspectors reviewed three operating experience issues (samples) to ensure that NRC generic concerns had been adequately evaluated and addressed by the licensee.

The operating experience issues listed below were reviewed as part of this inspection:

Generic Letter 96-01, Testing of Safety-Related Logic Circuits;

IN 89-07, Failures of Small-Diameter Tubing in Control Air, Fuel Oil, and Lube Oil Systems Which Render Emergency Diesel Generators Inoperable; and

IN 2010-23, Malfunctions of Emergency Diesel Generator Speed Switch.

b. Findings

No findings were identified.

.5 Modifications

a. Inspection Scope

The inspectors reviewed five permanent plant modifications related to selected risk significant components to verify that the design bases, licensing bases, and performance capability of the components had not been degraded through modifications. The modifications listed below were reviewed as part of this inspection effort:

Engineering Change (EC) 330522, Replace Existing Transformer T29 with New Style;

EC 376572, Replace Emergency Core Cooling System Low Pressure Permissive Pressure Switch 2-0263-52B;

EC 331868, Replace VERSA Solenoid Valves 2-1601-22, -23, -56 and -63 with Environmentally Qualified ASCO Solenoid Valves;

EC 341875, Install Bracing on 250 VDC MCCs and 125 VDC Distribution Panel - Seismic Qualification Utility Group -U2; and

EC 377973, Replace Capacitors C201, C202 & C203, Located on Essential Service System Inverter.

b. Findings

No findings were identified.

.6 Operating Procedure Accident Scenarios

a. Inspection Scope

The inspectors performed a detailed review of the procedures listed below associated with a sample of the selected risk-significant components selected for this inspection, specifically EDG 2, 480 VAC Bus 29, and the Unit 2 essential service system power supply and distribution panel 902-49. The procedures were compared to the UFSAR, design assumptions, and training materials to ensure consistency. For identified significant operator actions, the inspectors performed a detailed review and walk through of associated procedures, including observing the performance of operator actions in the stations simulator and in the plant, to assess operator knowledge level and training effectiveness. Additionally, the inspectors reviewed adequacy of selected procedural use and operator actions during execution of the following simulator scenario event.

Unit 2 was initially at full rated power, and the operators responded to a loss of offsite power, with a failure of EDG 2/3 to start/run, and no operator actions occur for the initial 10 minutes of the event. Specifically, the inspectors reviewed the following operating procedures in detail:

DGA-12, Loss of Offsite Power;

DOA 6600-01, Diesel Generator Failure;

DOP 6700-02, Transferring 480 Volt Busses; DOP 6800-01, Essential Service System; and

DEOP 0100-00, RPV [Reactor Pressure Vessel] Control.

The inspectors also performed a margin assessment and detailed review of four time critical operator actions. These actions were selected from the licensees site specific Operator Response Time program, and focused on the use of risk significant components selected for review during this inspection. Where possible, margins were determined by the review of the assumed design basis and UFSAR response times compared to validation performance times documented by job performance measures results. For the selected operator actions, the inspectors performed a detailed review and walk through of associated procedures, including observing the performance of simulated licensed operator actions in the stations control room, and in the plant by qualified plant operators to assess operator knowledge level, adequacy of procedures, and availability of special equipment where required.

The following operator actions were reviewed:

Time Critical Action 4; Initiate Low Pressure Coolant Injection Torus Cooling (Control Room Action) during Loss of Offsite Power;

Time Critical Action 16; Initiate Station Blackout Diesel Generators to Provide Power to 4kV Busses in Each Unit Following a Station Blackout;

Time Sensitive Action 21; Align Low Pressure Emergency Core Cooling System Pumps to the Condensate Storage Tanks (Specifically using the core spray pump); and

Time Sensitive Action ELAP6; Supply Power to 480 VAC Safety Related Busses (Specifically to provide power to Bus 902-49).

b. Findings

No findings were identified.

4OA2 Identification and Resolution of Problems

.1 Review of Items Entered Into the Corrective Action Program

a. Inspection Scope

The inspectors reviewed a sample of the selected component problems identified by the licensee and entered into the CAP. The inspectors reviewed these issues to verify an appropriate threshold for identifying issues and to evaluate the effectiveness of corrective actions related to design issues. In addition, corrective action documents written on issues identified during the inspection were reviewed to verify adequate problem identification and incorporation of the problem into the CAP. The specific corrective action documents sampled and reviewed by the inspectors are listed in the attachment to this report.

The inspectors also selected two issues identified during previous Component Design Bases Inspections to verify that the concern was adequately evaluated and corrective actions were identified and implemented to resolve the concern, as necessary. The following issues were reviewed:

NCV [Non-Cited Violation] 05000237/2013007-01; 05000249/2013007-01; Adequate Voltage not Assured for EDG Air Start Solenoid Valve; and

FIN [Finding] 05000237/2013007-03; 05000249/2013007-03; Failure to Ensure Functionality of High Pressure Coolant Injection Steam Supply Valve during an Anticipated Transient Without Scram.

b. Findings

No findings were identified.

4OA6 Management Meetings

Exit Meeting Summary

On February 26, 2016, the inspectors presented the inspection results to Mr. P. Karaba, and other members of the licensee staff. The licensee acknowledged the issues presented. Several documents reviewed by the inspectors were considered proprietary information and were either returned to the licensee or handled in accordance with NRC policy on proprietary information.

ATTACHMENT:

SUPPLEMENTAL INFORMATION

KEY POINTS OF CONTACT

Licensee

P. Karaba, Site Vice President

J. Washko, Station Plant Manager

J. Biegelson, Plant Engineering Manager

M. Budelier, Senior Engineering Manager

P. DiSalvo, Senior Engineer

D. Eaman, Electrical Design Engineer

J. Feigl, Engineering Manager

B. Franzen, Regulatory Assurance Manager

F. Gogliotti, Engineering Director

J. Hansen, Mechanical Design Engineer

M. Hosain, Site Equipment Qualification Engineer

B. Madderom, Engineering Manager

G. Morrow, Operations Director

M. Murskyj, Senior Engineering Manager

P. OBrien, Senior Site Assessor

F. Polak, Mechanical Design Engineer

P. Prater, Operations Training Manager

D. Walker, Regulatory Assurance - NRC Coordinator

F. Winter, Operations

D. Wolverton, Engineering Manager

U.S. Nuclear Regulatory Commission

D. Hills, Chief, Engineering Branch 1

G. Roach, Senior Resident Inspector

R. Elliot, Resident Inspector

LIST OF ITEMS OPENED, CLOSED, AND DISCUSSED

None