ML022270708

Approval of Implementation of Leak Before Break Technology by 12/31/2002

ML022270708
Person / Time
Site:	Palisades
Issue date:	08/08/2002
From:	Harden P Nuclear Management Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
CEN-367, CEN-367-A
Download: ML022270708 (10)

Text

Committed to Nuclear Excellence Palisades Nuclear Plant Operated by Nuclear Management Company, LLC August 8, 2002 10 CFR 50, Appendix A U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 DOCKET 50-255 - LICENSE DPR PALISADES NUCLEAR PLANT IMPLEMENTATION OF LEAK BEFORE BREAK TECHNOLOGY Nuclear Management Company, LLC proposes to eliminate the dynamic effects associated with high-energy pipe rupture in the primary coolant system from the licensing and design bases of the Palisades Plant. This change to the licensing and design bases is permitted by revised General Design Criterion 4 of Appendix A to 10 CFR 50.

By letter dated October 30, 1990, the Nuclear Regulatory Commission (NRC) provided acceptance to reference topical report CEN-367, "Leak-Before-Break Evaluation of Primary Coolant Piping in Combustion Engineering Designed Nuclear Steam Supply Systems." CEN-367-A (designated accepted) was issued in February 1991.

Attachment I provides the information requested by the NRC safety evaluation when referencing CEN-367-A.

NMC requests approval of the implementation of leak before break technology for the Palisades Plant by December 31, 2002.

SUMMARY

OF COMMITMENTS This letter contains no new commitments and no revisions to existing commitments.

Paul A. Harden Director, Engineering CC Regional Administrator, USNRC, Region III Project Manager, USNRC, NRR NRC Resident Inspector - Palisades Attachment 0

27780 Blue Star Memorial Highway 0 Covert, MI 49043 Telephone: 616.764.2000

ATTACHMENT I NUCLEAR MANAGEMENT COMPANY PALISADES NUCLEAR PLANT DOCKET 50-255 August 8, 2002 Comparison of Palisades Primary Coolant System Leak Detection Systems to NRZ Regulatory Guide 1.45 8 Pa-es Follow

Nuclear Management Company, LLC (NMC) is providing the following information to demonstrate that the primary coolant system (PCS) leakage detection systems installed at the Palisades Plant are consistent with the guidelines of Nuclear Regulatory Commission (NRC) Regulatory Guide (RG) 1.45, "Reactor Coolant Pressure Boundary Leakage Detection Systems," dated May 1973. A comparison of the diversity and sensitivity of Palisades' systems to the nine regulatory positions specified in Section C of RG 1.45 is presented.

1.

Leakage to the primary reactor containment from identified sources should be collected or otherwise isolated so that:

a.

the flow rates are monitored separately from unidentified leakage, and

b.

the total flow rate can be established and monitored.

NMC POSITION:

The requirements of Palisades Technical Specification (TS) 3.4.13, which addresses limits for ope-.ling with identified (and unidentified) primary coolant system (PCS) leakage, a.e consistent with this position. Compliance to the TS requirements is accomplished using installed plant leakage detection systems.

PCS flow rates from identified sources are determined and monitored in accordance with plant procedures.

The leakage detection systems installed are described in the responses to RG 1.45 positions 3 and 4 of this attachment. A Palisades Plant Computer (PPC) provides continuous monitoring of a large number of plant operating parameters, including indications to identify PCS leakage. The data trending capability of the PPC permits the operators to observe interactively the operating parameters and to readily detect anomalies.

2.

Leakage to the primary reactor containment from unidentified sources should be collected and the flow rate monitored with an accuracy of one gallon per minute (gpm) or better.

NMC POSITION:

Palisades TS 3.4.13 limit for unidentified PCS leakage is one gpm. A more detailed description of the Palisades leak detection capability is included in the response to RG 1.45 position 5 of this attachment. PCS flow rates from unidentified sources are determined and monitored in accordance with plant procedures.

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3.

At least three separate detection methods should be employed and two of these methods should be (1) sump level and flow monitoring and (2) airborne particulate radioactivity monitoring. The third method may be selected from the following:

a.

monitoring of condensate flow rate from air coolers,

b.

monitoring of airborne gaseous radioactivity.

Humidity, temperature, or the pressure monitoring of the containment atmosphere should be considered as alarms or indirect indication of leakage to the containment.

NMC POSITION:

The methods of detecting PCS to containment leakage available at Palisades satisfy the position. The methods are presented in the following three categories:

(i)

A containment surnp level monitoring system, which provides sump water level in the main control room by four level indicators. Two redundant Class 1 E instrument channels (magnetic float device) provide containment floor water level indication and are connected to an alarm panel in the control room. A diverse system provides two other redundant Class 1 E instruments and is connected to recorders in the control room. Each of the measurement channels is supplied from separate preferred ac power sources.

(ii)

Containment area radiation monitors that can detect radioactivity released to the containmenit. The monitors are considered equivalent to an airborne particu!at.e -dioactivity monitoring system with respect to PCS leak detection. This leak detection system consists of seven radiation monitors. Fcur containment isolation radiation monitors are installed on each of the containment air cooler discharge ducts; two containment gamma radiation monitors are installed at the perimeter of the containment dome; and one containment building gas monitor is installed on the containment ventilation system. All of these instruments, except the containment building gas monitor, are designated as IEEE Standard 308 Class 1E.

(iii)

Containment air cooler condensate flow monitoring satisfies this position.

The containment air cooler design includes a sump with a drain, a liquid level switch, and an overflow path. Normally very little water will be condensed from the containment atmosphere and the small amount of condensate will easily flow out through the sump drain. If leakage flow to 2

the sump is greater than 20 gpm, the level in the sump will rise to the liquid level switch and trigger an alarm in the control. Excessive flow to the sump is indicative of a service water leak, steam leak or a primary coolant system leak. A steam leak or primary coolant leak would be accompanied by an increase in the containment atmosphere humidity, which would be detected by the containment humidity sensors and displayed in the control room.

Additional systems in this category provided below collectively are considered alarms or indirect indication of unidentified leakage to the containment.

"* Containment atmosphere relative humidity detector. There are four humidity instruments available to monitor the containment atmosphere humidity.

"* Containment atmosphere temperature monitoring. Containment temperature and pressure fluctuate during plant operation, but a rise above the normally indicated range of values may indicate PCS leakage into containment. Reactor cavity, steam generator space and c,:,-itainment dome temperature are indicated in the control room. The system provides continuous display in the control room from the signals of four temperature instruments.

• Containment atmosphere pressure monitoring. Two redundant Class 1 E continuous wide-range pressure transmitters supplied from separate preferred ac power sources are installed and transmit signals to two recorders in the control room.

Letdown ar::* charging flow monitoring. A mismatch between the letdown and ci'43rg'ng flow rates may occur during plant operation due to minor !eakage ftom charging pump seals or other sources.

Therefore, during steady state plant power operation, any change in flow rates indicates potential unidentified PCS leakage.

Operators are required to check the charging and letdown flows hourly on the PPC. The PPC displays the letdown and charging flow rates to an accuracy of 0.01 gpm. Furthermore, any change in letdown and charging flow balance would also be reflected in other plant operating parameters such as the volume control tank water level. A change in time interval for making up the inventory would lead to an investigation.

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PCS leakage calculation based on PCS water inventory check.

The PCS leakage calculation is considered as the most accurate method in quantifying the PCS leakage. It is normally performed on a 24-hour interval. However, a confirmatory PCS inventory calculation may be performed anytime.

4.

Provisions should be made to monitor systems connected to the Reactor Coolant Pressure Boundary for signs of intersystem leakage. Methods should include radioactivity monitoring and indicators to show abnormal water levels or flow in the affected area.

NMC POSITION:

Intersystem leakage monitoring has been incorporated in the system design of the following piping systems, which directly interface with the PCS pressure boundary.

(i)

Main Steam Sy,-tem A primary-to-secondary leak would occur through the steam generators (SG) to the maia steam system. Palisades TS 3.4.13 contains a limit on primary-to-secondary leakage. There are three monitors available to assess this leakage: 1) main condenser air discharge system (off-gas), 2) main steam line radiation monitor, and 3) steam generator sample cooler/blowdown system.

(ii)

Component Cooling Water (CCW) System The CCW system it ::quipped with a radiation monitor mounted on the CCW pump discharge piping. The monitor can detect trace amounts of PCS leakage intc. tf'. CW system. In addition, PCS leakage into the CCW system would,e reflected in a CCW surge tank water level rise and CCW water temperature change. CCW surge tank water level is trended and logged in the control room hourly. Temperature instruments are installed on the piping sections of the return lines from the primary coolant pump heat exchangers. Signals from these temperature instruments are sent to recorders in the control room.

(iii)

Shutdown Cooling (SDC) System Palisades TS 3.4.14 addresses the limits on PCS pressure isolation valve (PIV) leakage. Palisades TS 3.4.14 also requires that both of the SDC suction valve interlocks to be operable when operating in Modes 1 4

through 3. Any PCS leakage through the interlocked valves is directed via a pressure relief valve, to the primary quench tank, which would cause quench tank water level and temperature to rise. The quench tank water level and temperature are indicated and alarm in the control room.

(iv)

Safety Injection System (SIS)

PCS leakage into the SIS is also subject to Palisades TS 3.4.14 limits on PIV leakage. The PCS system pressure boundary consists of two isolation valves at each boundary interface. PCS leakage through the first PIV would result in a pressure increase in the piping section between the two isolation valves or overflow to the safety injection tanks (SITs). The control room monitors the PIV leakage by the pressure instrumentation on the piping sections and the level instruments on the SITs.

5.

The sensitivity and response time of each leakage detection system in regulatory position 3. above employed for unidentified leakage should be adequate to detect a leakage rate, or its equivalent, of one gpm in less than one hour.

NMC POSITION:

(i)

Containment Sump Level Monitoring The containment sump level instrumentation described in response to regulatory position 3 provides a level signal to the control room indicators, the PPC and a control room alarm. Containment sump level from PPC data is trended and logged on control room data sheets once every hour.

The PPC has the trending capability to monitor small changes (accuracy to 0.001 ft.) in sum, ;avel over an hourly time scale. The PPC also has the capability to provide the sump fill rate in gpm (accuracy to 0.01 gpm) corresponding to tt.s -hanges in level. A rise in containment sump level of 0.1 ft. is equivalent to a>- addition of approximately 316 gallons of liquid.

The calibrated range of the indication is 5.5 ft at an accuracy of 0.25%

(accounting for all effects). The minimum accurate volume change is conservatively estimated to be 62 gallons. The minimum accurate detectable rate is approximately one gpm in one hour (62 gallons/60 minutes). Therefore, the leakage detection system should be adequate to detect a leakage rate of one gpm in less than one hour.

In the event the PPC is not available, operators would trend the sump level hourly using data from the sump level recorders in the control room.

Instructions are available to convert changes in level over time to leak rates in gpm.

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It is important to note that sump level changes can be indicative of leakage from any of the fluid systems located in the containment building such as PCS, service water, component cooling water, feedwater, or condensation of humidity within the containment atmosphere. Alarms or indications of increased PCS unidentified leakage would initiate more frequent PCS leak rate calculations. Operators would use the PCS leak rate calculations and chemical analysis to confirm the source of the leakage and to quantify the leak rate. Specifically, plant procedures require actions (once hourly trending has identified a rise in sump level) at leak rates significantly less than one gpm. Upon indications of a trend, the procedurally directed actions include a three-hour PCS leak rate calculation at stable plant conditions, a containment sump sample, PPC hourly sump level trending, and actions to correct the leakage. Therefore, the containment sump level monitoring system is considered to meet the position of RG 1.45.

(ii)

Containment Area Radiation Monitors The sensitivity or th.3e radiation monitors is primarily a function of the primary coolant rsdioactivity level and are therefore most effective when failed fuel is present in the reactor core. Containment atmosphere air mixing, to a lesser extent, may also affect the sensitivity of the radiation monitors. Palisades FSAR Section 4.7.1 describes the system's sensitivity based on a coolant activity level of 1 % failed fuel in the core.

The 1 % failed fuel assumption is consistent with Palisades design basis for radiation protectýion. With this assumed condition, the system is capable of detecting a very small leak of 100 cm3/min (0.026 gpm) in 45 minutes. However, if the primary coolant activity :evel was below an equivalent 1% failed fuel condition, which is normally the case during plant operation at Palisades, the timeframe to detect the leak could be greater than 45 minutes, or the leak rate would have to be higher than 0.026 gpm to ob detected in the same time period. Because the sensitivity of the mcnitors is dependent upon activity level, it cannot be stated with certainty for all possible activity levels that one gpm would be detected in less than one hour. Redundant monitoring from the other systems described would be available to meet the requirements of this position. In addition, the operators are required to check the trending data of the containment ventilation radiation monitor hourly. Therefore, the sensitivity of the system is judged to be adequate in meeting the RG 1.45 position during the applicable conditions.

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(iii)

Combination Leak Detection Systems In combination, the systems of this leak detection method are capable of detecting a one gpm PCS leak in one hour. Alarms or indications of increased PCS leakage from these systems, would initiate more frequent PCS leak rate calculations. The PCS leak rate calculations would be able to confirm the indicatiors and to quantify the leak rate in one hour.

6.

The leakage detection systems should be capable of performing their functions following seismic events that do not require plant shutdown. The airborne particulate radioactivity monitoring system should remain functional when subject to the safe shutdown earthquake (SSE).

NMC POSITION:

The Palisades FSAR describes how the plant design meets 10 CFR 50, Appendix A, General D3sign Criterion GDC-2, "Protection Against Natural Phenomena," for the structures, systems and components (SSC) important to safety that are required to resist seismic events. Palisades' design of SSCs conforms to the regulatory positions stated in RG 1.29, "Seismic Design Classification," and RG 1.100, "Seismic Qualification of Electrical and Mechanical Equipment for Nuclear Power Plants". Because the PCS leak detection systems support reactor safe shutdown operation, the equipment of these systems are required to be seismically qualified. Accordingly, there is reasonable assurance that the leak detection and airborne particulate radiation monitoring systems are capable of withstanding the designed seismic events.

7.

Indicators and alarms for each of leakage detection system should be provided in the main control room. Procedures for converting various indications to a common leakage equivalent should be available to the operators. The calibration of the indicators 3hould account for needed independent variables.

NMC POSITION:

The Palisades Plant fully complies with this position. Indicators and alarms for the leakage detection systems are provided in the main control room as previously described in response to position 3; procedures are available to the control room operators that convert the indications to a common leakage equivalent; and quality requirements are imposed on the instrument's calibration procedures to account for needed independent variables.

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8.

The leakage detection systems should be equipped with provisions to readily permit testing for operability and calibration during plant operation.

NMC POSITION:

The leakage detection systems are designed to permit testing for operability and calibration during plant operation. Palisades TS 3.4.15 surveillance requirements set forth the testing and calibration requirements for the PCS leak detection systems. The requirements of the testing frequencies considered instrument reliability. Operating experience has shown these frequencies are acceptable for detecting degradation. Tabulated below are the TS surveillance requirements.

Instrument Surveillance Frequency Containment Sump Level Indicator Channel Check 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> Containment Atmosphere Gaseous Channel Check 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> Activity Monitor Containment Atmosphere Humidity Channel Check 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> Monitor Containment Air Cooler Channel Functional Test 18 months Condensate Level Switch Containment Sump Level Indicator Channel Calibration 18 months Containment Atmosphere Gaseous Channel Calibration 18 months Activity Monitor Containment Atmosphere Humidity Channel Calibration 18 months Monitor In addition to the TS surveillance requirements, operators perform routine PCS leakage assessment using the PPC and PCS inventory verifications. The operators monitor a large number of instruments and parameters on daily, shiftly and hourly schedules. In the process, the operability and accuracy of these leak detection instruments are continually verified.

9.

The technical specifications should include the limiting conditions for identified and unidentified leakage and address the availability of various types of instruments to assure adequate coverage at all times.

NMC POSITION:

Palisades TS 3.4.13 addresses the limits for PCS operational leakage.

Palisades TS 3.4.14 addresses the limits for PCS leakage through pressure isolation valves. Palisades TS 3.4.15 addresses the PCS leakage detection instrumentation requirements.

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