Text

Report of Changes, Tests and Experiments
	ML063490286
Person / Time
Site:	Byron
Issue date:	12/13/2006
From:	Hoots D; Exelon Generation Co, Exelon Nuclear
To:	; Document Control Desk, Office of Nuclear Reactor Regulation
References
	BYRON 06-0142 LS-AA-104-1001, Rev 01
	Download: ML063490286 (41)
	v • d • e

Exe~onGeneration Company, LLC wwwexeloncorpcom Exekn. Nuci ear 4450 North German Church Road Byron, IL 610109794 10 CFR 50.59 (d)(2)

December 13, 2006 LTR: BYRON 2006-0142 File: 1.10.0101 United States Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Byron Station, Units 1 and 2 Facility Operating License Nos. NPF-37 and NPF-66 NRC Docket Nos. STN 50-454 and STN 50-455

Subject:

Report of Changes, Tests and Experiments Pursuant to the requirements of 10 CFR 50.59, Changes, tests and experiments, paragraph (d)(2), Byron Station is providing the required report for Facility Operating License Nos. NPF-37 and NPF-66. This report is provided for the 2005 and 2006 calendar years and consists of 50.59 Review Coversheets for changes to the facility or procedures as described in the Updated Final Safety Analysis Report (UFSAR) and tests or experiments not described in the UFSAR.

This report also includes 50.59 Review Coversheets for changes not previously submitted for the 2004 calendar year. These 50.59 Review Coversheets are associated with changes, tests and experiments not yet completed at the time of the last report.

Please direct any questions regarding this submittal to William Grundmann, Regulatory Assurance Manager, at (815) 406-2800.

Respectfull David M. Hoots Site Vice President Byron Nuclear Generating Station DMH/RC/rah , Byron Station 10 CFR 50.59 Report

Attachment 1 Byron Station 10 CFR 50.59 Report 10 CFR 50.59 Review Coversheets for Calendar Years 2005 and 2006 and 10 CFR 50.59 Review Coversheets not previously submitted for Calendar Year 2004

Design Change Packages (DCP), Drawing Change Requests (OCR), Engineering Changes (EC), and Temporary Modifications (TMOD)

1. 6G-04-0003 Rev. 0

2. 6G-04-0005 Rev. 0

3. 6G-04-0006 Rev. 1

4. 6G-04-0007 Rev. 0

5. 6G-06-0008 Rev. 0

6. 6G-05-0001 Rev. 0

7. 6G-06-0003 Rev. 0

50.59 REVIEW COVERSHEET FORM LS-AA-104-1001 Revision 1 Page 1 of 5 Station: Byron Uniti Activity/Document Number: EC #343598 Revision Number: ~

Title:

DEH Replacement NOTE: For 50.59 Evaluations, information on this form will provide the basis for preparing the biennial summary report submitted to the NRC in accordance with the requirements of 10 CFR 50.59(d)(2).

Description of Activity:

(Provide a brief, concise description of what the proposed activity involves.)

EC # 343598 replaces the existing Westinghouse Mod II Digital Electro-Hydraulic (DEH) control system for the main turbine with a redundant fault tolerant Westinghouse Ovation based Distributed Control System (DCS). All control algorithms and processes are redundant and configured to allow unrestricted operation with a single failure, and to facilitate on-line replacement of a failed component. The DCS has a continuous self-diagnostics that will trigger an alarm if a problem has been detected. The primary function of the new turbine control system (TCS) is to control the turbine in maintaining proper speed and load in the same manner as provided by the existing DEH system. In addition to the original DEH control functions, added Turbine Control System (TCS) functions include turbine protection against hazardous conditions, Turbine and Generator Temperature Monitoring (TGTMS), and Moisture Separator Reheater (MSR) controls. The modification will eliminate the current mechanical overspeed trip and replace it with a new electronic trip design. The modification will also change how the DEH responds to grid underfrequency events.

The existing hard control stations will be replaced by new operator workstations in the main control room and an engineering work station/historian in the computer room, The new system controls based on soft graphical interfaces will provide the same functionality as the existing equipment so that the operators can operate the TCS in a safe, predictable, and controlled manner.

Reason for Activity:

(Discuss why the proposed activity is being performed.)

The existing Digital Electro-Hydraulic (DEH) system has very little redundancy and fault tolerance. Due to the inherent limitations of the technology and design, numerous single failure points exist that could trip the turbine or initiate a plant transient. The existing DEH system requires extensive setup and calibration each refueling outage.

The existing DEH has limited diagnostic capability, which has resulted in unit trips due to lack of identification of failing components.

The new DCS includes extensive design features that provide the operator with information concerning the status of the new system. These include computer generated graphical interface screens, system failure alarms and indications, the ability to save for further review historical data and system information. The displays, alarms and event logging information that is available from the new system is more advanced and useful to the operator for detecting the cause of a transient. In addition, the DCS provides a single point of interface for the operator to perform functions associated with the DEH system.

Effect of Activity:

(Discuss how the activity impacts plant operations, design bases, or safety analyses described in the UFSAR.)

The new DCS system functions are modeled based on the existing system and includes an improved control strategy. The new system does not involve the various sensors and associated setpoints that are used by the Reactor

50.59 REVIEW COVERSHEET FORM LS-AA-1 04-1 001 Revision 1 Page 2 of 5 Station: Byron Uniti Activity/Document Number: EC #343598 Revision Number: Q

Title:

DEH Replacement Protection System (RPS) to initiate a preventative reactor trip. The modification does not impact the actuators.

Changes are being made to various system performance requirements to enhance performance and reliability by using redundant inputs and outputs. Therefore, the new DEH system will contain all the functions of the existing system with the following changes as noted below:

Two redundant Ovation controllers per drop are provided with the TCS. Only one controller in each drop is in control at ant time. The other is monitoring conditions and ready for hot swap over in case of a diagnosed failure. Each of the drops provides turbine protection and can cause a turbine trip. Each drop will protect against turbine overspeed conditions and will include a hard-wired overspeed trip system that will eliminate the mechanical overspeed. The system is independent of the controller logic and failure of both controllers in one drop. The hard-wired speed sensing modules will respond to turbine overspeed conditions in less than 10 msec.

The controller loop processing speeds for all speed and load control shall be set at 250 ms to ensure all dynamics within the system can be controlled reliably. This setting is based on Westinghouse experience with similar processes in other turbine protection applications. The control valve interfaces will operate at lOms loop to be highly responsive to minimize error between controller setpoint and valve position.

The Front Standard upgrade will include three new speed probes, which will be sensed by Ovation speed detector modules in the Emergency Trip System (ETS) controller. These speed modules have a independent trip subsystem built into them which are configured in a 2/3 configuration to trip the turbine via a new ETS trip manifold. The three control channel speed detector modules in the Operator Automatic (OA) / Overspeed Protection Control (OPC) controller will be configured also in a 2/3 configuration to trip the turbine via a second OA/OPC trip manifold. The additional OA/OPC controller provides for an independent and diverse means of overspeed protection. The manual trip from the main control board in the ETS and OP/OPC controller is processed through the controller and additionally independent of the controller for added protection.

The controller ioop processing speeds for all protection functions such as OPC, ETS, and overspeed shall be set at 50 ms to ensure that turbine protection is provided. This setting is based on Westinghouse experience with similar processes in other turbine protection applications.

The existing hydraulic trip logic has been modified such that two electrical trip manifolds using a one out of two taken twice solenoid arrangement is installed to provide redundancy. Each trip manifold is assigned to one of the two TCS controllers and actuated only by that controller.

The modulating valves such as throttle and governor valves, will switch to manual logic that is activated by detection of multiple bad sensors or multiple input channel bad quality (i.e. sensor signal out of range or failed).

The switch of the associated controls from automatic to manual mode is provided in a bumpless manner to avoid causing system transients.

Redundant outputs axe provided for the governor valves. Discrepancy logic is included for each governor valve to detect and alarm invalid governor valve positions, demand and errors, between primary valve interface and the backup.

Discrepancy logic is also provided to detect and alarm invalid valve position indications for reheat and intercept stop valves.

50.59 REVIEW COVERSHEET FORM LS-AA-1 04-1 001 Revision 1 Page 3 of 5 Station: Byron Uniti Activity/Document Number: EC #343598 Revision Number: ~

Title:

DEH Replacement

When a controller detects a trip condition, it will send a trip signal to the other controller to cause it to also trip.

These contacts are configured as and in the control logic to preclude false actuation in normal operating conditions.

The single pressure switches for monitoring condenser vacuum, thrust bearing oil pressure and bearing oils pressure will be replaced with three transmitters for each application. The logic for each system will be changed to a 2 out of 3 logic to increase reliability.

A local manual electrical trip switch has been added to the turbine front standard to replace manual trip lever that will cause a turbine trip via both trip manifolds when actuated. A manual emergency stop pushbutton is also available on the main control room panel independent of the digital system as in the existing design. The controls shall have a one out of one switch logic for manual tripping.

The TGTMS will be implemented in Ovation controller (Drop 2/52). The TGTMS collects data from a number of temperature detectors located on the turbine generator and performs calculations that will be displayed on an Ovation Operator station in the control room. The TGTMS also has hardwired annunciator outputs to two main control room annunciators for Warning Setpoint Exceeded and Trip Setpoint Exceeded.

EC 348178 modified the DEHC turbine control software input parameter SPDBMINS to reduce the potential for reactor power transients because of the DEHC response to grid under frequency events. The new system eliminates the potential for this event by improved monitoring of frequency and factoring of reactor power level into the software.

Removal of recorders 1TR-TSOO1B (LP Turbine Metal Temperature), 1TR-TSOO2A, B, C & D (Turbine Vibration, Expansion and Eccentricity, and IZR-T5003 (GV Valve Position, Rotor Speed, Rotor Position), and removal of LP turbine inlet steam temperature channels from other recorders 1TR-TSOO1D, E & F and rearranging the remaining recorders. The Ovation controller will replace the function of the removed recorders.

The electrical portion of the DEH will maintain the same functional and interface requirements as the current equipment with improved performance, except as follows:

a. Quantity, type and performance requirements for field and main control room instrumentation providing analog or digital input signals will be altered by this design change.

b. Quantity, type and performance requirements for field and main control room instrumentation driven by analog or digital output signals will be altered by this design change. Some analog output signals for recorders, indicators and computer inputs will be eliminated since these instruments will be driven directly by analog current signals. Some of digital output signals that were used for light indication or alarm functions in the existing system will be eliminated and replaced by new outputs performing different function since certain display and alarm functions in the new system will be replaced by new alarm and indication functions. Some digital outputs will be added to provide annunciation for Drop 2/52 emergency trip system controller and Drop 3/53 operator automatic and overspeed protection control function trouble alarms as a part of this EC.

50.59 REVIEW COVERSHEET FORM LS-AA-104-1 001 Revision 1 Page 4 of 5 Station: Byron Uniti Activity/Document Number: EC #343598 Revision Number: 0

Title:

DEH Replacement

c. 120 VAC power supply configuration has been altered by this design change. The new design provides redundant power supply for the new system using the existing power sources.

The new DCS system has been designed as a highly reliable system. This design is achieved through implementation of a combination of highly reliable components and fault tolerant design. The DCS self-tests and on-line diagnostics are capable of identifying failures in 110 cards, power supplies, processors and any of the modular components. These features identify the presence of a fault and determine the location of failure to a replaceable module level. Therefore, the DEH design assures that a single active component within the new system will neither result in a loss of continuous validated demand signals to TCS valves or operator displays nor will failure of individual modules cause the DCS system to trip the turbine or introduce a plant transient. The control elements in the new system are configured to allow unrestricted operation with a single failure, and to facilitate online replacement of a failed component. The existing control system is not-fault tolerant in automatic mode and does not provide on-line fault detection and failure response capability. Therefore, the new system improves the reliability of the entire DCS system.

Guidance was taken from EPRI Guidelines for Electromagnetic Interference Testing and for Licensing of Digital Upgrades (not specifically required for non-safety related upgrades) in the design of this change.

Summary of Conclusion for the Activitys 50.59 Review:

(Provide justification for the conclusion, including sufficient detail to recognize and understand the essential arguments leading to the conclusion. Provide more than a simple statement that a 50.59 Screening, 50.59 Evaluation, or a License Amendment Request, as applicable, is not required.)

This modification replaces the DEH Turbine Controls system with a more reliable system that uses logic based on the existing plant design updated to current control logic standard design. The DEH control system performs two main functions: control of turbine speed and control of turbine load. The controller compares signals representing turbine speed and first-stage pressure with reference values initiated by a load demand signal. The controller then puts out a comparison signal which actuates hydraulic control of the main turbine governor valves to match generator output to load demand. The system being modified is non-safety related and is not credited with any accident mitigation functions. The modification does not impact any of the devices or associated setpoints that provide anticipatory reactor trips due to turbine operating events. The modification does not change any valve response time or controls of any turbine valves. The response time of the valves is not credited in any accident analyses. The DEH system is one of a number of possible initiators of a plant turbine trip event (UFSAR 15.2.3). A detailed failure modes and effects analyses prepared as part of the modification shows that there is no significant increase in frequency of this event caused by the modification. Analysis has also shown that the probability of a turbine overspeed event has been reduced. The installation of the modified system does not result in any adverse interactions with any important to safety equipment in the plant.

A full 50.59 evaluation was performed because of the replacement of the mechanical overspeed trip with a trip generated by an electronic device (UFSAR Change 10-066 & TRM Change 04-008) and the incorporation of digital design components with a modified logic.

There is no change to any procedures described in the UFSAR.

There is no change to the Operating License or Technical Specification required by this modification.

50.59 REVIEW COVERSHEET FORM LS-AA-1 04-1 001 Revision 1 Page 5 of 5 Station: Byron Uniti Activity/Document Number: EC #343598 Revision Number: ~!

Title:

DEH Replacement In conclusion, the proposed activity does require a 50.59 evaluation, and the evaluation concluded that NRC notification of the proposed activity is not required.

Attachments:

Attach all 50.59 Review forms completed, as appropriate.

(NOTE: if both a Screening and Evaluation are completed, no Screening No. is required.)

Forms Attached: (Check all that apply.)

Applicability Review X 50.59 Screening 50.59 Screening 6E-04-0088 Re 0 No. ____________ v.

X 50.59 Evaluation 50.59 Evaluation 6G-04-0003 Re 0 No. v.

50.59 REVIEW COVERSHEET FORM LS-AA-104-1001 Revision 2 Page 1 of 3 Station: Byron Units 1 and 2 Activity/Document Number: EC 340545 (Ui) and EC 348121 (U2) Revision Number: 0

Title:

Replace Steam Generator Blowdown Condenser Hotwell Pump Moter Controller Description of Activity:

These changes will install replacement Steam Generator Blowdown Condenser Hotwell Pump variable speed drive Controllers (1/2SDO1JA & 1/2SDO1JB). The new controllers are Yaskawa/Magnetek Model GPDSO6 Digitally Controlled devices, and will replace the existing analog device controllers. The controllers provide power to the pumps identified as 1/2SDO2PA & PB.

Both the existing and new controllers convert 480 VAC 3-phase power feeds to a 3-phase variable speed output to drive the condenser hotwell pumps at a speed based on a variable level signal to each controller. The new controllers utilize digital processing and digital technology for the power signal conversion. Obsolescence and expensive serviceability of existing internal circuit boards on the existing controllers necessitates a more economical state-of-the-art component. The new controllers utilize a microprocessor and associated software, firmware, and hardware to provide signal processing options.

Reason for Activity:

The intent of these changes is to improve the performance and reliability of the controllers and to reduce maintenance expenses.

The existing controller components are experiencing increased failure rates due to age degradation and are also becoming obsolete. Servicing and replacing available parts is not economical compared to installing a newer style controller. The most economical replacement is a commercially manufactured digital controller and has been recommended by Byrons servicing vendor.

Effect of Activity:

The purpose of the steam generator blowdown subsystem is to maintain the steam generator water chemistry within specified limits for optimum operation. The system is a subsystem of the Liquid Radwaste processing (WX) system.

Continuous blowdown constantly removes impurities from the steam generators. The flow rate is varied as required to maintain the steam generator water chemistry within the required limits. During normal operation, blowdown is pumped from the steam generator blowdown condenser hotwells through the blowdown prefilters, the blowdown mixed-bed demineralizers, and the blowdown after filters to the condensate storage tanks or respective unit hotwell. In the event of high radioactive material in the purified effluent leaving the blowdown mixed-bed demineralizers, the effluent is diverted to the monitoring tanks.

These controller changes do not alter the system function nor any of the system flow paths, level controls, filtering processes, or component arrangements.

These changes affect the Steam Generator Blowdown Condenser Hotwell Pump Motor Controllers, which are components of the Steam Generator Blowdown (SD) system. The pumps are individually controlled and have a common suction and discharge path for parallel operation. The pumps respond to level changes in the hotwell condenser. Manual or automatic level control is selected from the operator station at the Radwaste Control Panel OPLO1J. Pump starts and pump parallel operation will not be affected differently using different controllers. The level sensing instrumentation will not be altered by these design changes.

Changes will also affect control wiring at Radwaste Control Panel OPLOIJ. The design function of the pumps and the blowdown system will not be altered by these changes. The controllers interface with the Auxiliary Power (AP) and Annunciator (AN) systems. None of these systems will be affected by utilizing different controllers. The structural integrity of controller cabinet seismic supports has been evaluated and will not be adversely affected. No other plant

50.59 REVIEW COVERSHEET FORM LS-AA-104-1001 Revision 2 Page 2 of 3 Station: Byron Units 1 and 2 Activity/Document Number: EC 340545 (Ui) and EC 348121 (U2) Revision Number: 0

Title:

Replace Steam Generator Blowdown Condenser Hotwell Pump Moter Controller equipment or systems will be affected. No electrical design evaluations, load monitoring systems or calculations require revision.

The effect of the change will be the more reliable operation of the system with reduced maintenance costs.

Summary of Conclusion for the Activitys 50.59 Review:

Although this design change introduces no adverse effects to any component or system functions, the replacement of the motor controllers was conservatively treated as adverse due to being in the category of an analog to digital upgrade. Therefore, a 50.59 evaluation has been performed.

Although different components susceptible to failure are being installed, the result and consequences of a malfunction or failure are not different than previously analyzed in the UFSAR and are therefore bounded by existing UIFSAR analyses. This change activity does not affect any accidents that have been evaluated in the UFSAR.

The effects of minor secondary system pipe breaks are considered in the chapter 15.1 analysis of events causing Increase in Heat Removal by the Secondary System. A blowdown system piping break would be bounded by the analysis. The controller changeout is not affecting the pumps integrity, the system piping integrity, nor any system boundaries. The motor controller function is to provide the variable speed changes to the pumps to control level in the hotwell condenser. Failure of the function would result in degradation of steam generator chemistry and adverse operational conditions, potentially leading to unit shutdown. This is the same result as with the existing controllers.

In addition, based on a technical review of new components and construction, Engineering has determined that there will not be more than a minimal increase in the likelihood of a malfunction, initiation (frequency) of a transient, or the likelihood of an accident.

Although a malfunction or failure of the new controller could result in the loss of the associated pump, the loss of a pump is not an accident initiator. Controller failure would have no different result than failure of the original controller. Failure or loss of one controller/pump would not cause failure of the parallel pump. If a common-mode defect in the controllers occurred, the result may cause simultaneous loss of both pumps. However, the Steam Generator Blowdown Condenser Hotwell Pumps do not have a function that is credited in the UFSAR for accident mitigation. The loss of Steam Generator Blowdown function would eventually result in degraded steam generator chemistry, an operational concern with ultimate consequences being a manual shutdown of the unit. Manual unit shutdown is described in Chapter 15.0 as a Condition I event- Normal Operation and Operational Transients. Using digital devices for motor controllers in the blowdown system would not result in any different failures that would cause the failure to propagate to a more severe condition.

A malfunction of the new controller may result in the loss of a blowdown condenser hotwell pump or the inability of a blowdown condenser hotwell pump to produce the expected flow rate. These potential malfunctions are the same that exist with the original motor controllers. Controller malfunction, ranging from failure to power the motor to powering the motor to a trip condition, would lead to loss of the blowdown function. This situation is bounded by UFSAR analyses as an anticipated plant transient. However, the new controller is no more likely to malfunction than the existing control system. Microcomputers have been utilized for control applications in industrial complexes and power plants for many years.

Although failure of the new digital control system could be considered a new failure mechanism, the failure mode and effect remains the same as that of existing controller failures. Therefore, no new failure modes or accidents will be created, and the IJFSAR analyses remains bounding.

50.59 REVIEW COVERSHEET FORM LS-AA-104-1001 Revision 2 Page 3 of 3 Station: Byron Units 1 and 2 Activity/Document Number: EC 340545 (Ul) and EC 348121 (U2) Revision Number: 0

Title:

Replace Steam Generator Blowdown Condenser Hotwell Pump Moter Controller The pump controllers affected by these changes do not provide any contribution as a fission product barrier, or affect any parameters which affect design basis limits for fission product barriers. The blowdown system piping and isolation valves at containment penetrations will not be affected by this activity. Therefore, these changes will not result in a design basis limit for a fission product barrier as described in the UFSAR being exceeded or altered.

In summary, the conclusion of the evaluation was that installation of the new controllers does not require a License Amendment. Therefore, the proposed changes may be implemented per applicable procedures.

Attachments:

Attach all 50.59 Review forms completed, as appropriate.

(NOTE: if both a Screening and Evaluation are completed, no Screening No. is required.)

Forms Attached: (Check all that apply.)

Applicability Review 50.59 Screening 50.59 Screening No. _________________ Rev. _______________

X 50.59 Evaluation 50.59 Evaluation 6G-04-0005 Rev. 0 No. ___________ _____

50.59 REVIEW COVERSHEET FORM LS-AA-104-1001 Revision 2 Page 1 of 3 Station/Unit(s): Byron/Unit 1 and 2 Activity/Document Number: EC #337049 Revision Number: 1 Id

Title:

Installation of Temporary Pumps for Draining the A SX Suction Piping NOTE: For 50.59 Evaluations, information on this form will provide the basis for preparing the biennial summary report submitted to the NRC in accordance with the requirements of 10 CFR 50.59(d)(2).

Description of Activity:

(Provide a brief, concise description of what the proposed activity involves.)

The EC installs temporary pumping systems to facilitate draining the A Essential Service Water (SX) System suction piping.

The temporary pumps will take suction from the IA and 2A SX Pump Strainer drains and pump the water to the common SX return header, 2SXO3B-42, via existing drain valves 0SX241 and 0SX242. Two separate temporary pumping systems will be installed. Each system will contain a pump, suction piping and hose, discharge piping and hose, manual isolation valves, a discharge check valve at the tie in to the SX return header drains, and a temporary power supply. The temporary pumps, piping, manual valves, and hose will be non-safety related non-ASME components. The temporary pumps will be powered from a local 480V welding receptacle.

Reason for Activity:

(Discuss why the proposed activity is being performed.)

The SX suction piping to the 1A and 2A pumps needs to be drained to facilitate replacement of the suction isolation valves 1/2SXOO1A. Replacement of the valves during B1R13 requires entering a 144 hour0.00167 days 0.04 hours 2.380952e-4 weeks 5.4792e-5 months LCOAR for the affected SX systems. Use of a temporary pump to drain the suction piping will minimize the time the system is out of service. Approximately 30,000 gallons of water need to be drained from the SX suction header. Returning the water to the SX system minimizes the amount of effluent released from the plant.

Effect of Activity:

(Discuss how the activity impacts plant operations, design bases, or safety analyses described in the UFSAR.)

Installation of the temporary pumping systems will have no adverse effect on plant equipment. Prior to being put in service the temporary pumps and piping will he isolated from the operating SX system by closed manual isolation valves. The temporary equipment, piping, and hose will be located/routed such that it does not interact with any safety related plant equipment. The additional temporary loads on the permanent SX system piping have been evaluated and is acceptable.

When the temporary pumping systems are put in service approximately 125 gpm of SX water will be pumped by each temporary pump from the strainer drain to the return header. The SX strainer will be isolated from the operating SX system which will allow the temporary pump to transfer water from the SX pump suction to the common return header. The temporary pumps will be tested with the Essential Service Water Cooling Tower (SXCT) suction isolation valve (OSX138A) open. During testing, the temporary pumps will bypass a small amount of flow from the SX suction to the return header. When the SXCT suction isolation valve is closed, the temporary pumps will be used to power drain the suction piping. During the power drain operation, the drained water will increase the amount of water returned to the SXCT basins. As basin level increases the automatic basin level control system will respond by reducing normal makeup to the SXCTs. The power drain operation will have no affect on the operating SX train. The SX trains are normally operated crosstied, thus all SX supplied equipment will be cooled by the operating SX train.

Summary of Conclusion for the Activitys 50.59 Review:

(Provide justification for the conclusion, including sufficient detail to recognize and understand the essential arguments leading to the conclusion. Provide more than a simple statement that a 50.59 Screening, 50.59 Evaluation, or a License Amendment Request, as applicable, is not required.)

The additional load of the temporary piping and hose on the permanent SX system piping has been evaluated and the stress remains within design allowables. Even though the pressure boundary components used for the temporary pumping system are not certified to ASME Section III requirements, the equipment and components are designed, manufactured, and tested for maximum working pressures above the design pressure of the SX system and the maximum pressure of the temporary pumps.

The pressure retaining components for the temporary change are judged to be equivalent to the current piping and components in the SX cooling system. Thus the probability of a SX system moderate energy line break while the temporary piping system forms part of the SX system pressure boundary is judged not to be more than a minimal increase. The installation of the

50.59 REVIEW COVERSHEET FORM LS-AA-104-l0Ol Revision 2 Page 2 of 3 Station/Unit(s): Byron/Unit 1 and 2 Activity/Document Number: EC #337049 Revision Number: 1

Title:

Installation of Temporary Pumps for Draining the A SX Suction Piping temporary pumping system will have no adverse impact on the operation of the SX system or any SX system components. The temporary equipment, piping, and hose will be locatedlrouted such that it does not interact with any safety related plant equipment.

Any debris that would bypass the strainer will be transported to the 42 diameter SX return header and back out to the SXCTs, thus there is no increase in the likelihood of debris blocking a SX system heat exchanger or isolation valve. Any debris that can pass through the temporary pump would pass through the SXCT spray nozzles. The small amount of bypass flow (250 gpm) will have negligible impact on the SX system flow balance because the flow rate is very small compared to the normal flow through the SX system of approximately 24,000 gpm per unit. Thus there is no increase in the likelihood of a malfunction of an operating SX train while the temporary pumps are in operation.

The reduction in normal makeup flow to the SXCTs will not increase the likelihood of a malfunction of the SX makeup systems because the system is designed to automatically adjust for changing basin level in response to changes in evaporation, drift, system leakage, and! or blowdown. Based on discussions with Chemistry, the temporary reduction in makeup flow will have negligible impact on the water chemistry of the SX system and will have no effect on the heat transfer rate of the system heat exchangers.

When the temporary piping system forms part of the SX system pressure boundary, a line break in the temporary piping would be terminated by shutdown of the temporary pump, manual isolation of the temporary suction piping isolation valves, and auto closure of a check valve located at the temporary piping tie-in to the return header. The suction piping is connected to the out of service SX suction header that is being drained, thus the loss of inventory does not adversely affect SX system operation. The temporary check valves located at the return header connection will prevent loss of inventory from the operating SX systems. A review of the flooding calculation shows that the flooding from a postulated break of the temporary piping system is bounded by postulated flooding from breaks of existing system piping. No safety related equipment other than the out of service A train SX equipment is located near the path of the temporary piping. Thus, a break of the temporary piping system will not result in spray or pipe whip that could adversely affect safe shutdown.

A hydraulic analysis of flow through the open safety related piping and gate valve shows that the break flow from the SX return header will be limited to 1100 gpm for a postulated line break and failure of the check valve connected to the SX return header or a break in the non-safety piping between the check valve and isolation valve. Assuming the check valve fails, operator action would be taken to manually close the gate valve to terminate the event. The loss of SX inventory from the operating return header would not adversely affect SX system operation because the SXCT basin contains adequate inventory margin for safe shutdown or accident mitigation.

The temporary pumping system does not introduce the possibility of a new accident because the temporary installation is not an initiator of any accident. Failure of the temporary pump to function only affects the rate of drain down of the isolated SX suction header. Pressure boundary failures have been previously evaluated and remain bounding. A comparison of UFSAR identified failures indicates that the results of the failure modes resulting from this EC are bounded by those presented in the UFSAR.

The proposed change does not affect the fuel clad, Reactor Coolant System (RCS) pressure boundary, or containment integrity.

SX system design functions are maintained to ensure that fission product barriers are not compromised due to a lack of safety related heat removal capability.

The additional load of the temporary piping and hose on the permanent SX system piping has been evaluated using the same method of evaluation (PIPSYS) described in the UFSAR. The evaluation methods for flooding associated with a moderate energy line break, SX basin water temperature, and SX makeup and minimum basin levels are not changed by the proposed activity.

Based upon the results of this evaluation, the activity may be implemented per plant procedures without obtaining a License Amendment.

50.59 REVIEW COVERSHEET FORM LS-AA-104-l001 Revision 2 Page 3 of 3 Station/Unit(s): Byron/Unit 1 and 2 Activity/Document Number: EC #337049 Revision Number: 1

Title:

Installation of Temporary Pumps for Draining the A SX Suction Piping Attachments:

Attach all 50.59 Review forms completed, as appropriate.

(NOTE: if both a Screening and Evaluation are completed, no ScreeningNo. is required.)

Forms Attached: (Check all that apply.)

Applicability Review 50.59 Screening 50.59 Screening No. ___________________ Rev. ________________

X 50.59 Evaluation 50.59 Evaluation No. 60-04-0006 Rev. 1 J C,

50.59 REVIEW COVERSHEET FORM LS-AA-104-1001 Revision 1 Page 1 of 5 Station: Byron Unit 2 Activity/Document Number: EC #343599 Revision Number: 0

Title:

DEH Replacement NOTE: For 50.59 Evaluations, information on this form will provide the basis for preparing the biennial summary report submitted to the NRC in accordance with the requirements of 10 CFR 50.59(d)(2).

Description of Activity:

(Provide a brief, concise description of what the proposed activity involves.)

EC # 343599 replaces the existing Westinghouse Mod II Digital Electro-Hydraulic (DEH) control system for the main turbine with a redundant fault tolerant Westinghouse Ovation based Distributed Control System (DCS). All control algorithms and processes are redundant and configured to allow unrestricted operation with a single failure, and to facilitate on-line replacement of a failed component. The DCS has a continuous self-diagnostics that will trigger an alarm if a problem has been detected. The primary function of the new turbine control system (TCS) is to control the turbine in maintaining proper speed and load in the same manner as provided by the existing DEH system. In addition to the original DEH control functions, added Turbine Control System (TCS) functions include turbine protection against hazardous conditions, Turbine and Generator Temperature Monitoring (TGTMS), and Moisture Separator Reheater (MSR) controls. The modification will eliminate the current mechanical overspeed trip and replace it with a new electronic trip design. The modification will also change how the DEH responds to grid underfrequency events.

The existing hard control stations will be replaced by new operator workstations in the main control room and an engineering work station/historian in the computer room. The new system controls based on soft graphical interfaces will provide the same functionality as the existing equipment so that the operators can operate the TCS in a safe, predictable, and controlled manner.

Reason for Activity:

(Discuss why the proposed activity is being performed.)

The existing Digital Electro-Hydraulic (DEH) system has very little redundancy and fault tolerance. Due to the inherent limitations of the technology and design, numerous single failure points exist that could trip the turbine or initiate a plant transient. The existing DEH system requires extensive setup and calibration each refueling outage.

The existing DEH has limited diagnostic capability, which has resulted in unit trips due to lack of identification of failing components.

The new DCS includes extensive design features that provide the operator with information concerning the status of the new system. These include computer generated graphical interface screens, system failure alarms and indications, the ability to save for further review historical data and system information. The displays, alarms and event logging information that is available from the new system is more advanced and useful to the operator for detecting the cause of a transient. In addition, the DCS provides a single point of interface for the operator to perform functions associated with the DEH system.

Effect of Activity:

(Discuss how the activity impacts plant operations, design bases, or safety analyses described in the UFSAR.)

The new DCS system functions are modeled based on the existing system and includes an improved control strategy. The new system does not involve the various sensors and associated setpoints that are used by the Reactor Protection System (RPS) to initiate a preventative reactor trip. The modification does not impact the actuators.

50.59 REVIEW COVERSHEET FORM LS-AA-1 04-1 001 Revision 1 Page 2 of 5 Station: Byron Unit 2 Activity/Document Number: EC #343599 Revision Number: ~

Title:

DEH Replacement Changes are being made to various system performance requirements to enhance performance and reliability by using redundant inputs and outputs. Therefore, the new DEH system will contain all the functions of the existing system with the following changes as noted below:

Two redundant Ovation controllers per drop are provided with the TCS. Only one controller in each drop is in control at any time. The other is monitoring conditions and ready for hot swap over in case of a diagnosed failure. Each of the drops provides turbine protection and can cause a turbine trip. Each drop will protect against turbine overspeed conditions and will include a hard-wired overspeed trip system that will eliminate the mechanical overspeed. The system is independent of the controller logic and failure of both controllers in one drop. The hard-wired speed sensing modules will respond to turbine overspeed conditions in less than 10 msec.

The controller loop processing speeds for all speed and load control shall be set at 250 msec to ensure all dynamics within the system can be controlled reliably. This setting is based on Westinghouse experience with similar processes in other turbine protection applications. The control valve interfaces will operate at lOms loop to be highly responsive to minimize error between controller setpoint and valve position.

The Front Standard upgrade will include three new speed probes, which will be sensed by Ovation speed detector modules in the Emergency Trip System (ETS) controller. These speed modules have a independent trip subsystem built into them which are configured in a 2/3 configuration to trip the turbine via a new ETS trip manifold. The three control channel speed detector modules in the Operator Automatic (OA) / Overspeed Protection Control (OPC) controller will be configured also in a 2/3 configuration to trip the turbine via a second OA/OPC trip manifold. The additional OA/OPC controller provides for an independent and diverse means of overspeed protection. The manual trip from the main control board in the ETS and OP/OPC controller is processed through the controller and additionally independent of the controller for added protection.

The controller loop processing speeds for all protection functions such as OPC, ETS, and overspeed shall be set at 50 ms to ensure that turbine protection is provided. This setting is based on Westinghouse experience with similar processes in other turbine protection applications.

The existing hydraulic trip logic has been modified such that two electrical trip manifolds using a one out of two taken twice solenoid arrangement is installed to provide redundancy. Each trip manifold is assigned to one of the two TCS controllers and actuated only by that controller.

The modulating valves such as throttle and governor valves, will switch to manual logic that is activated by detection of multiple bad sensors or multiple input channel bad quality (i.e. sensor signal out of range or failed).

The switch of the associated controls from automatic to manual mode is provided in a bumpless manner to avoid causing system transients.

Redundant outputs are provided for the governor valves. Discrepancy logic is included for each governor valve to detect and alarm invalid governor valve positions, demand and errors, between primary valve interface and the backup.

Discrepancy logic is also provided to detect and alarm invalid valve position indications for reheat and intercept stop valves.

50.59 REVIEW COVERSHEET FORM LS-AA-1 04-1 001 Revision 1 Page 3 of 5 Station: Byron Unit 2 Activity/Document Number: EC #343599 Revision Number: Q

Title:

DEH Replacement

When a controller detects a trip condition, it will send a trip signal to the other controller to cause it to also trip.

These contacts are configured as and in the control logic to preclude false actuation in normal operating conditions.

The single pressure switches for monitoring condenser vacuum, thrust bearing oil pressure, and bearing oil pressure will be replaced with three transmitters for each application. The logic for each system will be changed to a 2 out of 3 logic to increase reliability.

A local manual electrical trip switch has been added to the turbine front standard to replace manual trip lever that will cause a turbine trip via both trip manifolds when actuated. A manual emergency stop pushbutton is also available on the main control room panel independent of the digital system as in the existing design. The controls shall have a one out of one switch logic for manual tripping.

The TGTMS will be implemented in Ovation controller (Drop 2/52). The TGTMS collects data from a number of temperature detectors located on the turbine generator and performs calculations that will be displayed on an Ovation Operator station in the control room. The TGTMS also has hardwired annunciator outputs to two main control room annunciators for Warning Setpoint Exceeded and Trip Setpoint Exceeded.

EC 348178 modified the DEHC turbine control software input parameter SPDBMINS to reduce the potential for reactor power transients because of the DEHC response to grid under frequency events. The new system eliminates the potential for this event by improved monitoring of frequency and factoring of reactor power level into the software.

Removal of recorders 2TR-T5001B (LP Turbine Metal Temperature), 2VR-TSOO2A, B, C & D (Turbine Vibration, Expansion and Eccentricity, and 2ZR-TSOO3 (GV Valve Position, Rotor Speed, Rotor Position), and removal of LP turbine inlet steam temperature channels from other recorders 2TR-TSOO1D, E & F and rearranging the remaining recorders. The Ovation controller will replace the function of the removed recorders.

The electrical portion of the DEH will maintain the same functional and interface requirements as the current equipment with improved performance, except as follows:

a. Quantity, type and performance requirements for field and main control room instrumentation providing analog or digital input signals will be altered by this design change.

b. Quantity, type and performance requirements for field and main control room instrumentation driven by analog or digital output signals will be altered by this design change. Some analog output signals for recorders, indicators and computer inputs will be eliminated since these instruments will be driven directly by analog current signals. Some of digital output signals that were used for light indication or alarm functions in the existing system will be eliminated and replaced by new outputs performing different function since certain display and alarm functions in the new system will be replaced by new alarm and indication functions. Some digital outputs will be added to provide annunciation for Drop 2/52 emergency trip system controller and Drop 3/53 operator automatic and overspeed protection control function trouble alarms as a part of this EC.

c. 120 VAC power supply configuration has been altered by this design change. The new design provides redundant power supply for the new system using the existing power sources.

50.59 REVIEW COVERSHEET FORM LS-AA-1 04-1 001 Revision 1 Page 4 of 5 Station: Byron Unit 2 Activity/Document Number: EC #343599 Revision Number: Q

Title:

DEH Replacement The new DCS system has been designed as a highly reliable system. This design is achieved through implementation of a combination of highly reliable components and fault tolerant design. The DCS self-tests and on-line diagnostics are capable of identifying failures in 110 cards, power supplies, processors and any of the modular components. These features identify the presence of a fault and determine the location of failure to a replaceable module level. Therefore, the DEH design assures that a single active component within the new system will neither result in a loss of continuous validated demand signals to TCS valves or operator displays nor will failure of individual modules cause the DCS system to trip the turbine or introduce a plant transient. The control elements in the new system are configured to allow unrestricted operation with a single failure, and to facilitate online replacement of a failed component. The existing control system is not-fault tolerant in automatic mode and does not provide on-line fault detection and failure response capability. Therefore, the new system improves the reliability of the entire DCS system.

Guidance was taken from EPRI Guidelines for Electromagnetic Interference Testing and for Licensing of Digital Upgrades (not specifically required for non-safety related upgrades) in the design of this change.

Sununary of Conclusion for the Activitys 50.59 Review:

(Provide justification for the conclusion, including sufficient detail to recognize and understand the essential arguments leading to the conclusion. Provide more than a simple statement that a 50.59 Screening, 50.59 Evaluation; or a License Amendment Request, as applicable, is not required.)

This modification replaces the DEH Turbine Controls system with a more reliable system that uses logic based on the existing plant design updated to current control logic standard design. The DEH control system performs two main functions: control of turbine speed and control of turbine load. The controller compares signals representing turbine speed and first-stage pressure with reference values initiated by a load demand signal. The controller then puts out a comparison signal, which actuates hydraulic control of the main turbine governor valves to match generator output to load demand. The system being modified is non-safety related and is not credited with any accident mitigation functions. The modification does not impact any of the devices or associated setpoints that provide anticipatory reactor trips due to turbine operating events. The modification does not change any valve response time or controls of any turbine valves. The response time of the valves is not credited in any accident analyses. The DEH system is one of a number of possible initiators of a plant turbine trip event (UFSAR 15.2.3). A detailed failure modes and effects analyses prepared as part of the modification shows that there is no significant increase in frequency of this event caused by the modification. Analysis has also shown that the probability of a turbine overspeed event has been reduced. The installation of the modified system does not result in any adverse interactions with any important to safety equipment in the plant.

A full 50.59 evaluation was performed because of the replacement of the mechanical overspeed trip with a trip generated by an electronic device (UFSAR Change 10-066 & TRM Change 04-008) and the incorporation of digital design components with a modified logic.

There is no change to any procedures described in the UFSAR.

There is no change to the Operating License or Technical Specification required by this modification.

50.59 REVIEW COVERSHEET FORM LS-AA-1 04-1 001 Revision 1 Page 5 of 5 Station: Byron Unit 2 Activity/Document Number: EC #343599 Revision Number: Q

Title:

DEH Replacement In conclusion, the proposed activity does require a 50.59 evaluation, and the evaluation concluded that NRC notification of the proposed activity is not required.

Attachments:

Attach all 50.59 Review forms completed, as appropriate.

(NOTE: if both a Screening and Evaluation are completed, no Screening No. is required.)

Forms Attached: (Check all that apply.)

~. Applicability Review 50.59 Screening 50.59 Screening No. 6E-04-0155 Rev. 0 X 50.59 Evaluation 50.59 Evaluation 6G-04-0007 Rev. 0 No. ____________

50.59 REVIEW COVERSHEET FORM LS-AA-104-100l Revision 1 Page 1 of3 Station: Byron Unit 0 Activity/Document Number: EC 349308 Revision Number: JL

Title:

Upgrade to Spent Fuel Pool Bridge Crane OFHO5G Control System; remove position indexing software to free NOTE: For 50.59 Evaluations, information on this form will provide the basis for preparing the biennial summary report submitted to the NRC in accordance with the requirements of 10 CFR 50.59(d)(2).

Description of Activity:

(Provide a brief, concise description of what the proposed activity involves.)

This activity will install revised software in the microprocessor-based Control System, located in the Control Cabinet of the non-safety related Spent Fuel Pool Bridge Crane (SFPBC) OFHO5G. The existing SFPBC application reads from and writes to an external status file that tracks the actual physical location of the crane. The data in this file is used to determine the location of the SFPBC and calculate the rack and cell location, which is then displayed on the operators pendant. The SFPBC rack and cell location digital display on the pendants is for reference only; it is not required to be operational for fuel movement. Correct fuel assembly placement is the responsibility of the Fuel Handler and cognizant management personnel. The revised software will remove the position information displayed on the operators pendant. Removal of this portion of the application software will also disable the bridge slow zone at the end of bridge travel and the interlock that prevents diagonal motion while the SFPBC is in the transfer canal. This activity would not change the equipment the operator is using. The same skills of the operator will be used to avoidlprevent errors. The Operators control of the SFPBC and emergency shutdown of the SFPBC will not be changed. This activity does not require any hardware change.

Reason for Activity:

(Discuss why the proposed activity is being performed.)

This activity is expected to eliminate frequent failures of the microprocessor. Byron has experienced continuing problems with the Spent Fuel Pool Bridge Crane (SFPBC). Multiple Condition Reports have noted problems with the SFPBC controls. OPEX 0E10936 Spent Fuel Pool Bridge Crane Malfunction was issued to document these problems. In the crane control system, an error occasionally occurs when the program writes data to its solid-state disk drive. A data file is periodically updated by the position tracking system to store crane position information.

Currently the control program is stored in the same physical solid-state disk drive as the data file that the program writes to; this results in not only a data storage failure but also loss of the operating program for the crane. This condition results in the frequent faults, causing the microprocessor to reboot or stall. In most cases the computer reboots and operations continue normally; infrequently the system fails to reboot and requires the motherboard to be removed and reprogrammed. While similar, Braidwoods hardware and software is different. Braidwood does not have an indexing system with their version of the equipment.

Effect of Activity:

(Discuss how the activity impacts plant operations, design bases, or safety analyses described in the UFSAR.)

This activity installs revised software in the SFPBC control system. The revised software will remove the position indicating system. This activity also verifies that software associated with operational limits will not be changed.

This change will eliminate the need to update the position tracking file and therefore should eliminate the periodic corruption of the associated tracking file and application program.

This activity would not change the equipment the operator is using. It removes the position indication. This activity will allow operation of the SFPBC to continue to run within parameters allowed by the Westinghouse Fuel Specification Instructions, Cautions, and Limitations for Handling New and Partially Spent Fuel Assemblies; F-S Rev 17 dated 6-7-00. The same skills of the operator will be used to avoid/prevent errors. The Operators control of the SFPBC and emergency shutdown of the SFPBC will not be changed.

50.59 REVIEW COVERSHEET FORM LS-AA-104-1001 Revision I Page 2 of 3 Station: Byron Unit 0 Activity/Document Number: EC 349308 Revision Number: .JL..

Title:

Upgrade to Spent Fuel Pool Bridge Crane OFHO5G Control System; remove position indexing software to free computer memory.

Summary of Conclusion for the Activitys 50.59 Review:

(Provide justification for the conclusion, including sufficient detail to recognize and understand the essential arguments leading to the conclusion. Provide more than a simple statement that a 50.59 Screening, 50.59 Evaluation, or a License Amendment Request, as applicable, is not required.)

The non-safety related Spent Fuel Pool Bridge Crane (SFPBC) OFHOSG is used for handling fuel assemblies within the spent fuel storage area. This activity will install revised software, which will remove the position information displayed on the operators pendant. The SFPBC rack and cell location digital display on the pendants is for reference only and is not required to be operational for fuel movement. Removal of this portion of the application software will disable the bridge slow zone at the end of bridge travel and the interlock that prevents diagonal motion while in the transfer canal.

The SFPBC rack and cell location digital display and associated slow zone/transfer canal interlocks, are not credited with preventing a Fuel Handling Accident from occurring (UFSAR Section 15.7.4). Removing that portion of the application software does not involve any change to SSCs that adversely affect how UFSAR described design functions are performed or controlled. The proposed activity does not result in more than a minimal increase in the frequency of occurrence of an accident previously evaluated in the UFSAR because it is not an initiator of any accident, and it creates no new accident initiators. As such, the result and consequences of a malfunction or failure are not different than previously analyzed in the UFSAR and are therefore bounded by existing UFSAR analyses. Therefore, the proposed activity does not change the frequency of occurrence of any accidents previously evaluated in the UFSAR.

This activity is expected to resolve chronic problems with microprocessor failures. The position indication function of the software code requires periodically writing position information into a file, which is stored in the microprocessor memory location. Errors in writing position information into a file, which is stored in the microprocessor memory location, have caused corruption of the executable program. Removal of the position indexing software code should eliminate the file writing activity and eliminate the periodic corruption of the associated tracking file and application program. Therefore, the premise of this activity is to decrease the likelihood of equipment malfunction.

The non-safety related Spent Fuel Pool Bridge Crane rack and cell location digital display are not credited in a Fuel Handling Accident (UFSAR Section 15.7.4). The physical events accompanying a fuel handling accident do not prevent correct functioning of the controls and instrumentation of other safety systems, which provide active safety features following an accident, such as the Emergency Core Cooling System, emergency power, containment integrity, etc. Therefore, this activity will not increase the consequences of an accident previously evaluated in the UFSAR.

Removing that portion of the application software does not involve any change to SSCs that adversely affect how UFSAR described design functions are performed or controlled, This activity should resolve chronic problems with microprocessor failures. Therefore, the consequences of malfunction of an SSC important to safety previously evaluated in the UFSAR will not be increased.

This activity will install revised software, which will remove the position information displayed on the operators pendant. Removal of this portion of the application software will disable the bridge slow zone at the end of bridge travel and the interlock that prevents diagonal motion while in the transfer canal. Administrative procedure controls are in place and require the crane operator to approach travel limits at slow speeds and also travel in one direction only when in the transfer canal. The administrative controls, which apply both with the indexing system installed and also with the indexing system removed, will remain in place. These administrative controls do not rely on the slow zone or canal zone interlocks. The proposed activity does not create the possibility for an accident of a different type than previously evaluated in the UFSAR because it is not an initiator of any accident, and it creates no new accident initiators. Therefore, the proposed activity will not create possibility for an accident of a different type than previously evaluated in the UFSR.

50.59 REVIEW COVERSHEET FORM LS-AA-104-1001 Revision I Page 3 of 3 Station: Byron Unit 0 Activity/Document Number: EC 349308 Revision Number: .JL

Title:

Upgrade to Spent Fuel Pool Bridge Crane OFHO5G Control System; remove position indexing software to free computer memory.

The SFPBC does not physically interact with other SSCs important to safety, in which their failure could cause additional adverse conditions to other equipment. Any malfunction will end in the same result as a malfunction of the existing instrumentation.

Design basis limits for fission product barriers remain unchanged.

UFSAR Section 9.1.4.2.2 currently states that the SFPBC rack and cell location digital display on the pendants is for reference only and is not required to be operational for fuel movement. This activity will install a revision to software in the microprocessor-based Control System, located in the Control Cabinet of the Spent Fuel Pool Bridge Crane (SFPBC). The revised software will remove the position information displayed on the operators pendant. The SFPBC Rack and Cell location digital display on the pendants is for reference only and is not required to be operational for fuel movement. The SFPBC is operated manually and controlled administratively.

There is no change to any of the SFPBC functions. The Operators control of the SFPBC and emergency shutdown of the SFPBC remain the same. For this reason, the proposed activity does not result in a departure from a method of evaluation described in the TJFSAR that is outside the reference bounds of the design for that SSC or is inconsistent with analyses or descriptions in the UFSAR.

This activity does not impact operation of any systems specified in the Technical Specifications. No Technical Specification or Operating License change is required for this activity. However, an UFSAR change is required to revise section 9.1.4.2.2 and 9.1.4.3.1. DRP 11-002 has been initiated for this change. This change will reflect removal of the position information displayed on the operators pendant and the interlock that prevents diagonal motion while in the transfer canal.

Attachments:

Attach all 50.59 Review forms completed, as appropriate.

(NOTE: if both a Screening and Evaluation are completed, no Screening No. is required.)

Forms Attached: (Check all that apply.)

Applicability Review 50.59 Screening 50.59 Screening No. _________________ Rev. _______________

X 50.59 Evaluation 50.59 Evaluation 6G-04-0008 Rev. 0 No.

50.59 REVIEW COVERSHEET FORM LS-AA-104-100I Revision 2 Page 1 of 4 Station/Unit(s): BYRON UNIT 2 Activity/Document Number: EC 354059 Revision Number: 0

Title:

Zinc Iniection Into The CV Letdown Line and Reactor Coolant Systems NOTE: For 50.59 Evaluations, information on this form will provide the basis for preparing the biennial summary report submitted to the NRC in accordance with the requirements of 10 CFR S0.59(d)(2).

Description ofActivity:

(Provide a brief, concise description of what the proposed activity involves.)

The proposed activity installs a non-safety related vendor supplied zinc acetate chemical feed skid consisting of pumps, tanks, valves, and controls in the Auxiliary Building Unit 1 Containment Chiller Room. Along with the skid, necessary tubing, tubetrack, hangers, valves and power (12OVAC supplied by a local lighting panel) will be installed.

Additionally, some existing abandoned tubing will be removed and existing hangers will be modified.

The new 3/8 tubing will connect to the Chemical and Volume Control System (CV) System on the letdown line.

The skid will feed the zinc solution through the CV System into the Unit 2 Reactor Coolant System (RCS). The safety classification of Line 2CVG2B-3/8 (ASME Class 3) will be changed to non-safety and Valve 2CV8 129 will be changed from normally open to normally closed.

Upon completion of the installation, the soluble zinc acetate compound will be injected into the RCS during the later part of Byron Unit 2 Cycle 12. The goal is to establish a reactor coolant zinc concentration of 10 ppb during Cycle

12. A higher concentration during future cycles is limited to 40 ppb. All evaluations for zinc injection have been performed for 40 ppb for an eighteen-month fuel cycle, with temporary excursions of 80 ppb found acceptable. The analyses performed in support of this activity will allow the use of zinc injection for all future cycles with respect to fuel and non-fuel issues. With each fuel reload, cycle specific fuel rod design analyses are performed and are documented in the cycle specific Reload Safety Evaluation Report. The impact of zinc addition will be addressed in the cycle specific Reload Safety Evaluation Report for each future cycle. These cycle specific analyses will ensure that all fuel rod design criteria are met with due consideration of zinc addition effects.

The UFSAR will be updated (DRP 11-026) to discuss zinc injection into the Reactor Coolant System. The Fire Protection Report will be updated (FDRP 22-012) to reflect the installation of the zinc skid in the Unit 1 Auxiliary Building on El. 401.

Reason for Activity:

(Discuss why the proposed activity is being performed.)

Zinc injection is employed at numerous PWR plants similar to Byron Station. At low concentrations the zinc replaces radioactive cobalt, iron, and nickel in RCS component corrosion oxide layers. Overtime, this reduces radiation fields and subsequently personnel radiation dose. At higher concentrations, the zinc is known to inhibit general corrosion and initiation of primary water stress corrosion cracking (PWSCC) of Alloy 600 materials (e.g.,

Steam Generator tubes). Extensive testing, analysis, and operating experience at other plants has demonstrated the benefits of zinc injection without detrimental effects. Therefore, the decision has been made to implement zinc injection at Byron Station.

Effect of Activity:

(Discuss how the activity impacts plant operations, design bases, or safety analyses described in the UFSAR.)

With the exception of the following, all other technical issues involved with this activity have been addressed as having no impact on plant operations, design basis, or safety analysis as described in the UFSAR.

For RCS non-fuel components, the injection of zinc will cause the following effects: The ionic zinc will replace cobalt, nickel, and iron in the oxidation layers on components in the RCS. In the short term, these radionuclides will enter the coolant, causing radiation levels within the Containment and Auxiliary Building (primarily CV letdown piping and the Mixed Bed Demineralizers) to rise. In the long term, after a few fuel cycles and based on other plant experiences, the radiation levels within the plant will be reduced to below pre-zinc injection levels. The second

50.59 REVIEW COVERSHEET FORM LS-AA-104-1001 Revision 2 Page 2 of 4 Station/Unit(s): BYRON UNIT 2 Activity/Document Number: EC 354059 Revision Number: 0

Title:

Zinc Injection Into The CV Letdown Line and Reactor Coolant Systems effect of the zinc in higher concentrations will be to inhibit initiation of PWSCC. That is, testing has demonstrated that zinc is effective in reducing PWSCC initiation in Alloy 600 and other austenitic steels. The Steam Generator tubes at Byron 2 are composed of Alloy 600 material. Additionally, zinc has been demonstrated to be effective in reducing PWSCC corrosion rates of wetted RCS surfaces. Therefore, the use of zinc may be beneficial in reducing the possibility of corrosion-induced RCS pressure boundary failures. No detrimental effects on equipment or components (such as pump seals, heat exchanger performance) have been reported at plants using zinc injection.

During refueling outages, reactor coolant water will mix with refueling water. That is, when the reactor coolant water is mixed with water from the Refueling Water Storage Tanks (RWST) and the Spent Fuel Pool in the reactor cavity, some zinc will be transported into the Residual Heat Removal (RH) System, the Spent Fuel Pool, and the RWST. Because zinc injection will be terminated prior to a normal Unit shutdown and the large differences in volume between the RCS and RWST, the amount of zinc in the non-RCS systems will be insignificant.

Additionally, zinc will migrate from spent fuel into the Spent Fuel Pool water. Since the equipment, components and materials in these systems are similar to those in the RCS, the zinc will have no adverse affect on these systems or their operation.

The CV Mixed Bed Demineralizers will remove the liberated radionuclides in the coolant. This likely will result in higher demineralizer dose levels and possibly a reduction in mixed bed ion exchange resin longevity. However, all zinc addition plants discovered that they could operate for a complete fuel cycle on a single resin bed charge.

Likewise, filters (such as the Reactor Coolant Filter) may experience higher levels of contamination and/or require more frequent replacement. The plant demineralizers and filters will be monitored using existing plant equipment and procedures and preparations put in place to readily change-out resins and/or filters if the need arises. Based on industry experience, changes in radiation levels and demineralizer/filter differential pressure has typically been gradual.

As stated above, zinc injection will be terminated prior to a planned Unit shutdown or subsequent to an unplanned shutdown. This is because of the retrograde solubility of zinc with temperature. As the RCS temperature is reduced, zinc concentration levels in the coolant will tend to increase. A zinc concentration of 80 ppb (twice the maximum allowable concentration for Mode 1 operation) for short excursions has been analyzed and found acceptable.

Increases above 80 ppb for Modes other than Mode 1 are acceptable.

Industry operating experience indicates there will be an insignificant effect on Crud Induced Power Shift (CIPS) due to zinc injection on the corrosion of ZIRLCO fuel cladding in Units that have low and medium duty cores. While the magnitude of CIPS due to zinc addition induced crud deposits on the core is unknown for a high duty core (Byron),

an evaluation was performed to predict oxide layer (crud) thickness. The evaluation conservatively bounds any increases in corrosion thickness that can be expected due to zinc addition.

To mitigate risk associated with CIPS, nickel concentrations and axial power distribution will be monitored throughout the cycle. Chemistry procedures have been developed to monitor RCS chemistry for zinc addition.

Existing flux mapping surveillances will be employed to measure axial power distribution. Excessive coolant nickel levels or indications of CIPS may result in the cessation of zinc addition.

Based on the above limitations and monitoring, zinc injection will not cause fuelcladding corrosion levels to exceed their design parameters.

Sununary of Conclusion for the Activitys 50.59 Review:

(Provide justification for the conclusion, including sufficient detail to recognize and understand the essential arguments leading to the conclusion. Provide more than a simple statement that a 50.59 Screening, 50.59 Evaluation, or a License Amendment Request, as applicable, is not required.)

The proposed zinc injection into the Reactor Coolant System will not result in a minimal increase in the frequency of occurrence of an accident previously evaluated in the UFSAR since the zinc has no adverse affect on pressure

50.59 REVIEW COVERSHEET FORM LS-AA-104-lOOl Revision 2 Page 3 of 4 Station/Unit(s): BYRON UNIT 2 Activity/Document Number: EC 354059 Revision Number: 0

Title:

Zinc Injection Into The CV Letdown Line and Reactor Coolant Systems boundary integrity, the small flow and volume of zinc solution does not increase operator response time during boron dilution events, the amount of concentrated zinc solution used for injection is small and has no affect in case of a spill on Main Control Room habitability, the new installation is designed and installed to the appropriate codes and standards to prevent any interaction with safety related equipment and the possibility of increased corrosion on the fuel is limited by the chemistry sampling and core monitoring to prevent oxidation from reaching design limits.

Therefore, there is no increase in the frequency of occurrence of an accident previously evaluated in the IJFSAR.

The proposed zinc injection will not result in a minimal increase in the likelihood of occurrence of a malfunction of an SSC import to safety previously evaluated in the UFSAR since there is no or insignificant affect on hydrogen generation, ECCS water pH and Recirculation Sump blockage; there are no adverse affects on any equipment or components in the RCS or ECCS or their performance; fuel oxidation thicknesses remain within design parameters; and procedures developed to control zinc injection do not interface with plant operation.

The proposed zinc injection will not result in more than a minimal increase in the consequences of an accident previously evaluated in the UFSAR since there is no adverse affect on any fission product barrier, the release associated with the zinc oxide layerduring a postulated accident would be a small fraction of the total release, zinc injection does not change the response of the RCS and engineered safeguard systems to postulated accident conditions, there is no increase in post-LOCA hydrogen generation in the Containment, there is no increase in the potential for Recirculation Sump blockage, there is no change in sump water pH, there is no increase in operator response time to a boron dilution event, during normal operation a break in the new tubing is bounded by existing analysis, during a LOCA, the new tubing is isolated on a Containment isolation signal, there is no affect on any Chapter 15 accidents. Therefore, zinc injection does not result in more than a minimal increase in the consequences of an accident previously evaluated in the UFSAR.

Zinc injection will not result in more than a minimal increase in the consequences of a malfunction of an SSC important to safety previously evaluated in the UFSAR since there is no equipment malfunction that would result in a larger release to the environment, there is no affect on systems and components used to mitigate the consequences of postulated accidents, no fission product barriers are degraded, radiation release both planned and during accidents have been evaluated any increase due to zinc injection is bounded by existing analyses, and no affect on equipment qualification due to increase radiation levels in the plant. Therefore, zinc injection does not result in more than a minimal increase in the consequences of a malfunction of an SSC important to safety previously evaluated in the UFSAR.

Zinc addition will not create a possibility for an accident of a different type than any previously evaluated in the UFSAR since zinc is not the initiator of any accident, zinc does not introduce a new failure mode in fission product barriers, zinc will not change the manner in which the plant is operated, existing pipe break analyses bound any postulated breaks, zinc does no alter the response of the RCS or engineered safeguards system to transient conditions and there is no affect on Main Control Room habitability.

Zinc injection will not create a possibility for a malfunction of an SSC important to safety with a different result than previously evaluated in the UFSAR since there are no postulated malfunctions, there are no adverse impacts on the operation or function of any SSCs and all new components have been designed to meet existing plant criteria.

Zinc addition will not result in a design basis limit for a fission product barrier as described in the UFSAR being exceeded or altered since the oxide layer altered by zinc is thinner and inhibits stress corrosion cracks and the fuel will be monitored such that the design basis parameters are not exceeded.

The methods of evaluation described in the UFSAR used in establishing the design basis and safety analysis were employed to support the conclusions drawn in evaluating the use of zinc. Additionally, the qualification of the components used in the installation was performed consistent with the UFSAR.

50.59 REVIEW COVERSHEET FORM LS-AA-104-100I Revision 2 Page 4 of 4 Station/Unit(s): BYRON UNIT 2 Activity/Document Number: EC 354059 Revision Number: 0

Title:

Zinc Injection Into The CV Letdown Line and Reactor Coolant Systems With the presently performed fuel and non-fuel analyses and with the limitations, monitoring and/or testing imposed by future cycle specific Reload Safety Evaluation Reports, zinc injection can be implemented without further evaluation.

Attachments:

Attach all 50.59 Review forms completed, as appropriate.

(NOTE: if both a Screening and Evaluation are completed, no Screening No. is required.)

Forms Attached: (Check all that apply.)

Applicability Review 50.59 Screening 50.59 Screening No. _________________ Rev. _______________

X 50.59 Evaluation 50.59 Evaluation 6G-05-0001 Rev. 0 No. ____________ ___________

Exe~onGeneration Company, LLC wwwexeloncorpcom Exekn. Nuci ear 4450 North German Church Road Byron, IL 610109794 10 CFR 50.59 (d)(2)

December 13, 2006 LTR: BYRON 2006-0142 File: 1.10.0101 United States Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Byron Station, Units 1 and 2 Facility Operating License Nos. NPF-37 and NPF-66 NRC Docket Nos. STN 50-454 and STN 50-455

Subject:

Report of Changes, Tests and Experiments Pursuant to the requirements of 10 CFR 50.59, Changes, tests and experiments, paragraph (d)(2), Byron Station is providing the required report for Facility Operating License Nos. NPF-37 and NPF-66. This report is provided for the 2005 and 2006 calendar years and consists of 50.59 Review Coversheets for changes to the facility or procedures as described in the Updated Final Safety Analysis Report (UFSAR) and tests or experiments not described in the UFSAR.

This report also includes 50.59 Review Coversheets for changes not previously submitted for the 2004 calendar year. These 50.59 Review Coversheets are associated with changes, tests and experiments not yet completed at the time of the last report.

Please direct any questions regarding this submittal to William Grundmann, Regulatory Assurance Manager, at (815) 406-2800.

Respectfull David M. Hoots Site Vice President Byron Nuclear Generating Station DMH/RC/rah , Byron Station 10 CFR 50.59 Report

Attachment 1 Byron Station 10 CFR 50.59 Report 10 CFR 50.59 Review Coversheets for Calendar Years 2005 and 2006 and 10 CFR 50.59 Review Coversheets not previously submitted for Calendar Year 2004

Design Change Packages (DCP), Drawing Change Requests (OCR), Engineering Changes (EC), and Temporary Modifications (TMOD)

1. 6G-04-0003 Rev. 0

2. 6G-04-0005 Rev. 0

3. 6G-04-0006 Rev. 1

4. 6G-04-0007 Rev. 0

5. 6G-06-0008 Rev. 0

6. 6G-05-0001 Rev. 0

7. 6G-06-0003 Rev. 0

50.59 REVIEW COVERSHEET FORM LS-AA-104-1001 Revision 1 Page 1 of 5 Station: Byron Uniti Activity/Document Number: EC #343598 Revision Number: ~

Title:

DEH Replacement NOTE: For 50.59 Evaluations, information on this form will provide the basis for preparing the biennial summary report submitted to the NRC in accordance with the requirements of 10 CFR 50.59(d)(2).

Description of Activity:

(Provide a brief, concise description of what the proposed activity involves.)

EC # 343598 replaces the existing Westinghouse Mod II Digital Electro-Hydraulic (DEH) control system for the main turbine with a redundant fault tolerant Westinghouse Ovation based Distributed Control System (DCS). All control algorithms and processes are redundant and configured to allow unrestricted operation with a single failure, and to facilitate on-line replacement of a failed component. The DCS has a continuous self-diagnostics that will trigger an alarm if a problem has been detected. The primary function of the new turbine control system (TCS) is to control the turbine in maintaining proper speed and load in the same manner as provided by the existing DEH system. In addition to the original DEH control functions, added Turbine Control System (TCS) functions include turbine protection against hazardous conditions, Turbine and Generator Temperature Monitoring (TGTMS), and Moisture Separator Reheater (MSR) controls. The modification will eliminate the current mechanical overspeed trip and replace it with a new electronic trip design. The modification will also change how the DEH responds to grid underfrequency events.

The existing hard control stations will be replaced by new operator workstations in the main control room and an engineering work station/historian in the computer room, The new system controls based on soft graphical interfaces will provide the same functionality as the existing equipment so that the operators can operate the TCS in a safe, predictable, and controlled manner.

Reason for Activity:

(Discuss why the proposed activity is being performed.)

The existing Digital Electro-Hydraulic (DEH) system has very little redundancy and fault tolerance. Due to the inherent limitations of the technology and design, numerous single failure points exist that could trip the turbine or initiate a plant transient. The existing DEH system requires extensive setup and calibration each refueling outage.

The existing DEH has limited diagnostic capability, which has resulted in unit trips due to lack of identification of failing components.

The new DCS includes extensive design features that provide the operator with information concerning the status of the new system. These include computer generated graphical interface screens, system failure alarms and indications, the ability to save for further review historical data and system information. The displays, alarms and event logging information that is available from the new system is more advanced and useful to the operator for detecting the cause of a transient. In addition, the DCS provides a single point of interface for the operator to perform functions associated with the DEH system.

Effect of Activity:

(Discuss how the activity impacts plant operations, design bases, or safety analyses described in the UFSAR.)

The new DCS system functions are modeled based on the existing system and includes an improved control strategy. The new system does not involve the various sensors and associated setpoints that are used by the Reactor

50.59 REVIEW COVERSHEET FORM LS-AA-1 04-1 001 Revision 1 Page 2 of 5 Station: Byron Uniti Activity/Document Number: EC #343598 Revision Number: Q

Title:

DEH Replacement Protection System (RPS) to initiate a preventative reactor trip. The modification does not impact the actuators.

Changes are being made to various system performance requirements to enhance performance and reliability by using redundant inputs and outputs. Therefore, the new DEH system will contain all the functions of the existing system with the following changes as noted below:

Two redundant Ovation controllers per drop are provided with the TCS. Only one controller in each drop is in control at ant time. The other is monitoring conditions and ready for hot swap over in case of a diagnosed failure. Each of the drops provides turbine protection and can cause a turbine trip. Each drop will protect against turbine overspeed conditions and will include a hard-wired overspeed trip system that will eliminate the mechanical overspeed. The system is independent of the controller logic and failure of both controllers in one drop. The hard-wired speed sensing modules will respond to turbine overspeed conditions in less than 10 msec.

The controller loop processing speeds for all speed and load control shall be set at 250 ms to ensure all dynamics within the system can be controlled reliably. This setting is based on Westinghouse experience with similar processes in other turbine protection applications. The control valve interfaces will operate at lOms loop to be highly responsive to minimize error between controller setpoint and valve position.

The Front Standard upgrade will include three new speed probes, which will be sensed by Ovation speed detector modules in the Emergency Trip System (ETS) controller. These speed modules have a independent trip subsystem built into them which are configured in a 2/3 configuration to trip the turbine via a new ETS trip manifold. The three control channel speed detector modules in the Operator Automatic (OA) / Overspeed Protection Control (OPC) controller will be configured also in a 2/3 configuration to trip the turbine via a second OA/OPC trip manifold. The additional OA/OPC controller provides for an independent and diverse means of overspeed protection. The manual trip from the main control board in the ETS and OP/OPC controller is processed through the controller and additionally independent of the controller for added protection.

The controller ioop processing speeds for all protection functions such as OPC, ETS, and overspeed shall be set at 50 ms to ensure that turbine protection is provided. This setting is based on Westinghouse experience with similar processes in other turbine protection applications.

The existing hydraulic trip logic has been modified such that two electrical trip manifolds using a one out of two taken twice solenoid arrangement is installed to provide redundancy. Each trip manifold is assigned to one of the two TCS controllers and actuated only by that controller.

The modulating valves such as throttle and governor valves, will switch to manual logic that is activated by detection of multiple bad sensors or multiple input channel bad quality (i.e. sensor signal out of range or failed).

The switch of the associated controls from automatic to manual mode is provided in a bumpless manner to avoid causing system transients.

Redundant outputs axe provided for the governor valves. Discrepancy logic is included for each governor valve to detect and alarm invalid governor valve positions, demand and errors, between primary valve interface and the backup.

Discrepancy logic is also provided to detect and alarm invalid valve position indications for reheat and intercept stop valves.

50.59 REVIEW COVERSHEET FORM LS-AA-1 04-1 001 Revision 1 Page 3 of 5 Station: Byron Uniti Activity/Document Number: EC #343598 Revision Number: ~

Title:

DEH Replacement

When a controller detects a trip condition, it will send a trip signal to the other controller to cause it to also trip.

These contacts are configured as and in the control logic to preclude false actuation in normal operating conditions.

The single pressure switches for monitoring condenser vacuum, thrust bearing oil pressure and bearing oils pressure will be replaced with three transmitters for each application. The logic for each system will be changed to a 2 out of 3 logic to increase reliability.

A local manual electrical trip switch has been added to the turbine front standard to replace manual trip lever that will cause a turbine trip via both trip manifolds when actuated. A manual emergency stop pushbutton is also available on the main control room panel independent of the digital system as in the existing design. The controls shall have a one out of one switch logic for manual tripping.

The TGTMS will be implemented in Ovation controller (Drop 2/52). The TGTMS collects data from a number of temperature detectors located on the turbine generator and performs calculations that will be displayed on an Ovation Operator station in the control room. The TGTMS also has hardwired annunciator outputs to two main control room annunciators for Warning Setpoint Exceeded and Trip Setpoint Exceeded.

EC 348178 modified the DEHC turbine control software input parameter SPDBMINS to reduce the potential for reactor power transients because of the DEHC response to grid under frequency events. The new system eliminates the potential for this event by improved monitoring of frequency and factoring of reactor power level into the software.

Removal of recorders 1TR-TSOO1B (LP Turbine Metal Temperature), 1TR-TSOO2A, B, C & D (Turbine Vibration, Expansion and Eccentricity, and IZR-T5003 (GV Valve Position, Rotor Speed, Rotor Position), and removal of LP turbine inlet steam temperature channels from other recorders 1TR-TSOO1D, E & F and rearranging the remaining recorders. The Ovation controller will replace the function of the removed recorders.