ML22024A114

IP 71111.07 Heat Exchanger/Sink Performance

ML22024A114
Person / Time
Issue date:	02/18/2022
From:	Shawn Campbell NRC/NRR/DRO/IRIB
To:
Stephen.Campbell@nrc.gov
Shared Package
ML22048B189	List: Inspection Manual Change Notice 22-004, Table of Contents for Inspection Manual Change Notice 22-004 ML21307A038 ML22024A114
References
CN 22-004
Download: ML22024A114 (18)

Text

Issue Date: 02/18/22 1

71111.07 NRC INSPECTION MANUAL IRIB INSPECTION PROCEDURE 71111 ATTACHMENT 07 HEAT EXCHANGER/SINK PERFORMANCE Effective Date: 02/18/2022 PROGRAM APPLICABILITY: IMC 2515 A CORNERSTONES:

Initiating Events Mitigating Systems Barrier Integrity INSPECTION BASES:

See Inspection Manual Chapter (IMC) 0308, Attachment 2 SAMPLE REQUIREMENTS Sample Requirements Minimum Baseline Completion Sample Requirements Budgeted Range Sample Type Section(s) Frequency Sample Size Samples Hours Heat Exchanger/Sink 03.01 Annual 1 per site 1-2 7 +/- 1 1 at Vogtle Units 3 & 4 Heat Exchanger (Service Water Cooled) 03.02 Triennial 2 per site*

Not Required at Vogtle Units 3 & 4 2-4 Not Required at Vogtle Units 3 & 4 40 +/- 6 Heat Exchanger (Closed Loop) 03.03 Ultimate Heat Sink 03.04 Ultimate Heat Sink Containment Device and Dam**

03.05 Sexennial 1 per site Not Required at Vogtle Units 3 & 4

• When performed, the 03.05 Sample shall count toward minimum baseline sample requirement for 03.02, 03.03, and 03.04.

• • This sample is not required at Catawba, Comanche Peak, Farley, Harris, McGuire, North Anna, and V.C. Summer since the NRCs Dam Safety Program inspects the ultimate heat sink (UHS) dams at these sites.

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71111.07 71111.07-01 INSPECTION OBJECTIVES 01.01 To verify that any potential heat exchanger deficiencies which could mask degraded performance are identified. Applies to all risk significant or safety-related heat exchangers directly or indirectly connected to service water systems or the UHS, including heat exchangers in closed cooling water systems.

01.02 To verify that any potential common cause heat sink performance problems that have the potential to increase risk are identified (e.g., icing and grassing at circulating and service water intake structures or discharge silting).

01.03 To verify that the licensee has adequately identified and resolved heat sink performance problems that could result in initiating events or affect multiple heat exchangers in mitigating systems and thereby increase risk (e.g., component cooling water heat exchanger performance affected by corrosion, fouling, or silting).

71111.07-02 GENERAL GUIDANCE Apply risked informed insights together with other factors, such as engineering analysis and judgment, operating experience, previous inspection results, performance history, and renewed licensee aging management or other program actions (e.g., inspections, tests, etc.) that the licensee agreed to implement to determine which heat exchangers and/or heat sinks will be selected for review. Consider previously inspected heat exchangers and/or heat sinks during the last three years (to avoid undue duplication). Select two to four heat exchangers or heat sink samples. For selected heat exchangers, perform appropriate sections of 03.02 (heat exchangers cooled by service water) or 03.03 (closed loop cooling heat exchangers) as determined by the inspector. For selected heat sinks (other than a heat exchanger), perform appropriate sections of 03.04 or 03.05 as determined by the inspector.

When scheduling this inspection, consider refueling outage and at-power maintenance schedules to identify opportunities to observe infrequent activities associated with risk significant heat exchangers or service water inspections/testing (e.g., heat exchanger inspections and testing, internal service water pipe inspections, external underground service water pipe inspections).

For plants with a renewed license, aging management programs and implementing activities may have resulted in additional or different requirements and/or commitments. The inspector should review these aging management program descriptions and commitments as part of informing sample selections. The applicable aging management programs may include, but are not limited to: open-cycle cooling water, closed treated water systems, water chemistry, selective leaching and buried and underground piping and tanks. Additionally, licensees may have conducted one-time, internal surface inspections of components in the cooling water systems associated with the heat exchangers or the UHS. These inspections would have been in accordance with the one-time inspection and inspection of internal surfaces in miscellaneous piping and ducting components aging management programs.

Refer to the table below for selecting inspection activities to achieve each cornerstone objective and to those activities that have a risk priority (i.e., those common-cause failures with a reasonable probability of occurring should be targeted by inspection to determine impact on cornerstones).

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71111.07 Cornerstone Inspection Objective Risk Priority Example Initiating Events Evaluate events, issues, or conditions involving the degradation or loss of both the normal and ultimate heat sinks.

Common-cause issues affecting heat removal capabilities.

Icing and grassing of a circulating water and service water intake structure or discharge silting.

Mitigating Systems/

Barrier Integrity Evaluate any potential degraded performance of heat exchangers/

containment fan coolers Heat exchanger selection should focus on the potential for common-cause failures or on potentially high-risk heat exchangers with a low margin to their design point or the high potential for fouling.

Degraded containment cooling or component cooling water heat exchanger performance due to corrosion, fouling, silting, etc.

For each sample, routine review of problem identification and resolution activities should be conducted using IP 71152, Problem Identification and Resolution. Problems involving silting, water hammer, voiding, corrosion, and fouling should be reviewed. Focus on events or conditions that could cause the loss of a heat exchanger/sink due to events such as heat transfer problems, improper cleaning, ice buildup, grass intrusion, leaks/breaks, or blockage of pipes and components. Determine whether the licensee has appropriately considered common-cause failures. If any loss of heat exchanger/sink events have occurred, these should receive review priority. Review the corrective actions to determine if actions were enough to prevent/address recurrence of the problem.

71111.07-03 INSPECTION SAMPLES 03.01 Heat Exchanger/Sink.

Verify heat exchanger and/or heat sink readiness and availability.

Specific Guidance

a. Heat exchanger/sink performance can be reviewed by observation, by evaluating test data/reports, or both. These tests should be those typically sanctioned by industry. Test acceptance criteria and results have appropriately considered differences between testing conditions and design conditions (functional testing at design heat removal rate may not be practical); and the test results have appropriately considered test instrument inaccuracies and differences.

b. Verify periodic maintenance activities are with consistent licensee commitments made in response to Generic Letter (GL) 89-13. The principal EPRI guidance documents related to GL 89-13 program implementation are TR-107397, Service Water Heat Exchanger Testing Guidelines, for service water heat exchanger thermal performance testing, and 1003320, Supplemental Guidance for Testing and Monitoring Service Water Heat Exchangers. Early guidance consisted of EPRI NP-7552, Heat Exchanger

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71111.07 Performance Monitoring Guidelines, although it has largely been replaced by the additional detail in TR-107397. Guidance is provided in EPRI 1009839, Heat Exchanger Single Tube Test Device, for an alternative heat exchanger test method which does not require testing of the entire tube bundle.

c. Bio-fouling controls can be reviewed by observation, by evaluating data/reports, or both.

The licensee should have acceptance criteria for bio-fouling controls which are based on an industry standard, supportive program results, or the recommendation of the appropriate vendors.

d. Heat exchanger inspections can be observed to identify the state of tube cleanliness and the number and condition of plugged tubes. Primarily focus on whether the number of tubes plugged affects the heat exchanger's operability and not the biofilm on the inside of tubes which should be covered in the triennial inspection, by a specialist. The licensee should have acceptance criteria that indicates the maximum number of tubes that may be plugged for a specific heat exchanger and a basis for that acceptance criteria.

e. Check, by either a walkdown or the review of operations data, any or all of the following:

1. The heat exchangers inlet and/or outlet temperatures.

2. Primary or secondary side fluid flow.

3. If there is any evidence of leaks.

4. Whether the heat exchanger can perform its safety-related or risk significant function by reviewing documentation or results of licensee inspections.

5. Comparison of end bell orientation of one heat exchanger to the orientation of a similar redundant train heat exchanger, to confirm proper orientation. Improper end bell orientation can significantly reduce or isolate flow to an otherwise functional heat exchanger.

f. Determine if heat exchanger is correctly categorized under the Maintenance Rule and verify if it is receiving the required maintenance.

03.02 Heat Exchanger (Service Water Cooled)

Verify that the selected service water cooled heat exchanger(s) remain capable of performing their intended safety functions.

Specific Guidance This section is applicable only to heat exchangers cooled by service water (e.g., those cooled directly by raw water).

a. For the selected heat exchangers that are directly cooled by the service water system, verify that testing, inspection, maintenance, and monitoring of biotic fouling and macrofouling programs are singularly or in combination adequate to ensure proper heat transfer.

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b. Review the method and results of heat exchanger performance testing or equivalent methods to verify performance. Verify the following items, as applicable:

1. The selected test methodology is consistent with accepted industry practices, or equivalent.

2. Test conditions (e.g., differential temperatures, differential pressures, and flows) are consistent with the selected methodology.

3. Test acceptance criteria (e.g., fouling factors, heat transfer coefficients) are consistent with the design basis values.

4. Test results have appropriately considered differences between testing conditions and design conditions (functional testing at design heat removal rate may not be practical). Test results need to be extrapolated to the heat exchanger design conditions.

5. Frequency of testing based on trending of test results is sufficient (based on trending data) to detect degradation prior to loss of heat removal capabilities below design basis values. Test result trends which show a step change in heat exchanger performance should be justified.

6. Test results have considered test instrument inaccuracies and differences. Test instruments should be calibrated and set on appropriate range for the parameters to be measured; otherwise small measurement errors could affect the test results. The required accuracy of the instruments depends on the margins available between the calculated parameter based on the test results and the limiting design condition.

7. Tube and shell side heat loads are equal if adequate information is available in test results to calculate these two values.

c. For inspection/cleaning, review the methods and results of heat exchanger performance inspections or observe the actual inspection/cleaning. Refer to either design assumptions in calculations or parameters on design data sheets that can be evaluated by observation, review of licensee inspection records, or review of procedural operation limits. Verify the following first three steps 1 thru 3, if conducting the review and the last step 4 only if actually observing the inspection/cleaning:

1. Methods used to inspect, and clean heat exchangers are consistent with as-found conditions identified and expected degradation trends and industry standards.

Methods are adequate, based on identified degradation trends, if they ensure no loss of capability between scheduled inspections or cleanings.

2. Inspection and cleaning activities have established acceptance criteria and are consistent with industry standards. Acceptance criteria considers fouling factor and heat transfer coefficient, consistent with design assumptions and as-found conditions. The inspection and cleaning frequency is consistent with as-found conditions and identified trends. Based on the inspection and/or cleaning frequency, and the identified trends, the acceptance criteria are adequate to ensure no loss of operability or functionality during scheduled in-service period.

Issue Date: 02/18/22 6

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3. As-found results are recorded, evaluated, and appropriately dispositioned such that the as-left condition is acceptable. Changes in trends are identified and evaluated.

The licensee has evaluated the as-left condition and determined, based on frequency and trend, the heat exchanger would remain operable (or identified limitations to ensure operable but degraded) through the in-service period until the next inspection.

4. If observing the inspection/cleaning then perform the following:

(a) Prior to cleaning, inspect the extent of fouling and blockage of tubes. Look for indications that bypass flow may be occurring due to divider plate wear on heat exchanger inlet and/or outlet end bell(s).

(b) Inspect the condition of the cleaned surfaces.

(c) Verify that the actual number of installed tube plugs agree with the recorded tube plug data, as documented in controlled drawings and heat transfer calculations.

(d) Verify that both ends of the same tube are plugged.

(e) Look for indications of macrofouling, including live or dead mussels and clams, plant material, or silt. Indications of macrofouling include accumulation of silt or sediment, live or dead mussels or clams, aquatic material (e.g., fish, algae, grass, kelp, etc.), and foreign material from maintenance or construction activities (i.e., gasket material or other debris).

(f) Verify end bell and flange gaskets are properly installed. Verify the use of sealants in combination with gaskets.

(g) Verify end bell orientation is correct after final installation. Improper end bell orientation can significantly reduce or isolate flow to an otherwise functional heat exchanger.

d. Verify condition and operation are consistent with design assumptions in heat transfer calculations, and as described in the final safety analysis report. The inspector can refer to either design assumptions in calculations or parameters on design data sheets that can be evaluated by observation, review of licensee inspection records, or review of procedural operating limits. Verify that the as-found condition of the heat exchanger tube inner surfaces is consistent with the fouling factor used in design calculations, or credited in design basis documents or the Updated Final Safety Analysis Report (UFSAR).

e. Verify the licensee has evaluated the potential for water hammer in susceptible heat exchangers and undertaken appropriate measures to address it. Heat exchangers susceptible to water hammer include but are not limited to heat exchangers kept isolated in standby or dry lay-up, heat exchangers that can partially drain during design basis events (i.e., loss of offsite power (LOOP) or loss of coolant accident (LOCA)), such as containment air coolers, and containment heat exchangers in which flow is temporarily stopped following a station blackout or other event.

f. Verify adequate controls and operational limits are in place to prevent heat exchanger degradation due to excessive flow induced vibration during operation. Heat exchangers

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71111.07 that exhibit excessive flow induced vibration may be susceptible to potential damage to their tubes or tube sheets. Such heat exchangers may be identified based on direct observation during high flow conditions (i.e., tube rattle), issues identified in corrective action documents (e.g., vibration during operation, unexpected or excessive tube damage), issues identified during interviews of licensee staff, and administrative limits procedurally established to limit flow according to manufacturer's recommendations or engineering calculations. Additionally, review system flow balance results and individual heat exchanger flow data. Verify the licensee is maintaining the calculated flow through each heat exchanger.

g. Review, if available, periodic flow testing at or near maximum design flow for redundant and infrequently used heat exchangers.

h. Verify that the number of plugged tubes are within pre-established limits, based on heat transfer capacity and design heat transfer assumptions, and are appropriately accounted for in heat exchanger performance calculations.

i.

Review, if available, eddy current test reports and visual inspection records, to determine the structural integrity of the heat exchanger.

03.03 Heat Exchanger (Closed Loop)

Verify that the selected closed loop heat exchanger(s) remain capable of performing their intended safety functions.

Specific Guidance This section is applicable only to heat exchanges that are cooled by closed cooling water systems (e.g., RHR heat exchangers not directly connected to the service water system).

These heat exchangers are directly cooled by a closed cooling water system, and either indirectly cooled by the service water system, or cooled directly by an air radiator. Examples of risk significant or safety related heat exchangers that are air cooled at some nuclear plants (i.e., no reliance on the service water system or UHS) include station blackout diesel generator, emergency diesel generator, or instrument air compressors.

For the selected heat exchangers that are directly cooled by a closed loop cooling water system, verify the following items:

a. Condition and operation are consistent with design assumptions in heat transfer calculations. Design assumptions used in calculations and parameters on design data sheets can be compared to observations, inspection records, and operating procedure limits.

b. Potential for water hammer in susceptible heat exchangers has been evaluated and appropriately addressed. Heat exchangers susceptible to water hammer include those heat exchangers kept isolated in standby or dry lay-up and heat exchangers that can partially drain during design basis events (i.e., LOOP or LOCA), such as containment air coolers.

c. Controls and operational limits are in place to prevent heat exchanger degradation due to excessive flow induced vibration during operation. Heat exchangers that exhibit excessive flow induced vibration may be susceptible to potential damage to their tubes

Issue Date: 02/18/22 8

71111.07 or tube sheets. Such heat exchangers may be identified based on direct observation during high flow conditions (i.e., tube rattle), issues identified in corrective-action documents (e.g., vibration during operation, unexpected or excessive tube damage), and issues identified during interviews of licensee staff. Administrative limits are procedurally established to limit flow according to manufacturer's recommendations or engineering calculations.

d. Chemical treatment programs for corrosion control were consistent with industry standards, and are controlled, tested, and evaluated. Chemical treatment programs should be consistent with industry standards. Treatment results should be evaluated for adverse effects on heat exchangers or other system components, should consider stress corrosion cracking, and should conform to licensee established acceptance criteria.

Chemical treatments should be conducted as scheduled, controlled, and the results monitored, trended, and evaluated.

e. Available periodic flow testing at or near maximum design flow for redundant and infrequently used heat exchangers meets design specifications. System flow balance results and individual heat exchanger flow data should be reviewed to check that the licensee is maintaining the calculated flow through each heat exchanger.

f. The number of plugged tubes are within pre-established limits, based on heat transfer capacity and design heat transfer assumptions, and are appropriately accounted for in heat exchanger performance calculations.

g. Available eddy current test reports and visual inspection records indicate the structural integrity of the heat exchanger is maintained during operation.

03.04 Ultimate Heat Sink Verify that the UHS remains capable of performing its intended safety functions.

Specific Guidance This section is applicable only to UHS. For each UHS selected, verify the performance of UHS and their subcomponents like piping, intake screens, pumps, valves, etc. by tests or other equivalent methods. For heat sinks, the issue is their availability and accessibility to the in-plant cooling water systems. The UHS and its subcomponents should be assessed to gain reasonable assurance that they are capable of performing their intended risk significant or safety functions.

Perform at least two of the following five items below (i.e., a, b, c, d, and e) for each selected UHS.

a. For an UHS such as a forced draft cooling tower or spray pond, perform a system walkdown and review licensee records to verify the following items, as applicable:

1. Sufficient reservoir capacity.

2. Periodic monitoring and trending of sediment build-up.

3. Adjacent non-seismic or non-safety-related structures cannot degrade or block safety-related flow paths, during a severe weather or seismic event.

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4. Periodic performance monitoring of heat transfer capability.

5. Periodic performance monitoring of the UHS structural integrity.

b. Review operation of service water system and UHS.

1. Review design changes to the service water system and the UHS. Review of changes or modifications to ensure that key design basis requirements were considered as inputs and maintained. Consideration may be given to reviewing planned modifications as well as age-related changes that have the potential to adversely impact the UHS design basis including intake structures, reservoir and dam material conditions.

2. Review licensee procedures for a loss of the service water system or UHS. Verify that instrumentation, which is relied upon for decision making, is available and functional. Procedures should include specific guidance for a loss of intake structure, loss of all service water pumps, or pipe rupture, as applicable. Intake bay water level instrumentation may be used by emergency operating procedures (EOPs) and Emergency Plan emergency action levels (EAL), during abnormal or emergency conditions. Locations for measuring the technical specification UHS water level and the emergency plan EAL UHS water level should be effectively the same.

3. Review licensee controls to prevent clogging due to macrofouling. Verify that macrofouling is adequately monitored, trended, and controlled, consistent with maintenance program frequencies and assumptions. Verification can be satisfied by test results, observation, or other equivalent methods that verify the UHS and sub-components can accommodate maximum system flow. During 2004 to 2006, industry operating experience showed several events involving foreign material intrusion into the systems. These events included clogging of system piping, heat exchangers, strainers, and trash racks due to intrusion of aquatic life (e.g., fish, algae, grass, kelp, etc.), floating or submerged river debris, or entrained silt and sediment. Additional considerations include over-population of small fish that could be pulled into the system, live or dead zebra mussels or Asiatic clams, and other foreign material from maintenance or construction activities (i.e., gasket material, or other debris).

GL 89-13 recommended that once per refueling outage, a visual inspection for macroscopic biological fouling, sediment, and corrosion, and for removal of any accumulation. Some licensees have made commitments pursuant to GL 89-13 to minimize the potential for clogging equipment. Susceptible components may include heat exchangers with small diameter tubes, or small passages in flat plate style heat exchangers, valves or heat exchangers with low velocity flow rates, valves or heat exchangers in low elevation locations, and valves that are typically closed in dead legs.

4. If applicable, verify biocide treatments, for biotic control, were conducted as scheduled, controlled, and the results monitored, trended, and evaluated. The biocide treatment program should be consistent with industry standards. Treatment results should conform to licensee established acceptance criteria and maintain satisfactory biotic control. In addition, microbiological induced corrosion (MIC) should be monitored, trended, and controlled.

Issue Date: 02/18/22 10 71111.07

5. For fixed volume UHS (i.e., not a river, lake, or ocean), verify adequate chemistry monitoring to ensure adequate pH, calcium hardness, etc. are maintained.

Inadequate chemistry monitoring or control can result in calcium plate-out on hot heat exchanger tubes during a design basis event. Langeliers Index is a common water quality chemistry analysis which can be used to reduce the likelihood of degrading the heat transfer coefficient due to calcium deposits.

6. Strong-pump weak-pump interaction. For susceptible system designs, verify the licensee monitors pump performance for potential strong-pump weak-pump interaction, during routine system operation and testing, and following pump maintenance. System design is susceptible to strong-pump weak-pump interaction whenever two (or more) centrifugal pumps operate in parallel and share a common minimum flow line. If one of the pumps is stronger (i.e., has a higher developed head for the same flow rate) than the other, the weaker pump may be dead-headed when the pumps are operating under low flow conditions, such as the mini-flow mode. Compare vendor pump curves, or pump curves developed during system testing, for differences in pump discharge pressure at the same flow rates. Review licensee's response to Bulletin 88-04. During single pump testing, compare pump head at low flow rates. Review licensee's system hydraulic model, for assumptions on mini-flow, or case studies with parallel pumps operating in the mini-flow mode.

c. Review performance testing of service water system and UHS.

1. Review performance tests, such as ASME inservice tests, for a sample of pumps, tower fans, and valves in the service water system. The flushing and flow testing provisions of GL 89-13 also apply to service water cross-tie lines between units. In addition, pump runout conditions should not be present with the minimum number of pumps operating with worst-case alignment on non-safety related loads. Refer to IP 71111.22, Surveillance Testing, for additional guidance.

2. Review service water flow balance test results for adverse effects. Compare flow balance results to system configuration and flow assumptions during design basis accident conditions. System flow balance data should be consistent with key design assumptions, such as flow coefficients, pressure drops across components and piping during accident alignment configurations, rated heat removal flow rates, and total system flow specifications.

3. Review periodic testing, inspection, or monitoring of valves that interface with safety-related service water and non-safety related (i.e., non-ASME class 3) or non-seismic piping systems to verify adequate isolation capability during a design basis event.

Verify that the licensee's methodology is adequate for the leakage rate assumptions in their design basis (i.e., flow divergence or UHS total volume).

4. Verify performance of risk significant non-safety related functions, such as back-up cooling to turbine building or reactor building closed cooling water systems, air compressors, or turbine driven auxiliary feedwater systems.

d. Perform a system walkdown and review documentation for the selected service water and/or closed cooling water systems to verify the following items, as applicable:

1. For buried or inaccessible piping, review the licensee's pipe testing, inspection, or monitoring program to verify structural integrity, and ensure that any leakage or

Issue Date: 02/18/22 11 71111.07 degradation has been appropriately identified and dispositioned. Piping inspection and monitoring programs should include periodic checks of riser penetrations (e.g., a vertical pipe coming up through a cement floor or foundation) and should also include checks of inspection manways on large bore piping (e.g., where the manway attaches to the pipe).

2. Review, if available, ultrasonic test results and/or visual inspections to determine the structural integrity of the piping.

3. Review licensee's disposition of any active thru wall pipe leaks, including completed or planned corrective actions and structural evaluations.

4. Review history of thru wall pipe leakage to identify any adverse trends since the last NRC inspection (i.e., about two to three years).

5. For closed cooling water systems, review operating logs or interview operators or system engineers, to identify adverse make-up trends that could be indicative of excessive leakage out of the closed system. Perform a walkdown of the system, including the head or surge tank to verify system integrity and material condition.

6. Review the periodic inspection program used to detect protective coating failure, corrosion, and erosion.

7. For deep draft vertical pumps, review operational history and IST vibration monitoring results for adverse trends. Common deep draft vertical pump problems include, shaft coupling failures due to corrosion, corrosion of shaft ends and/or coupling bolts has led to elongation of shaft, and resulted in pump damage (IN 07-05), shaft bearing cooling problems, inability to detect pump degradation, and backward pump rotation with pump off or standby, which can result in fatigue failure of shaft coupling when pump is started. Numerous failures have resulted from misalignment, imbalance, installation errors, and intergranular stress corrosion cracking (IGSCC), and operating experience includesBulletin 79-15, and Information Notices 80-07, 93-68, 94-45, and 07-05.

e. Perform a walkdown and review documentation for the service water intake structure to verify the following items, as applicable:

1. Proper functioning of traveling screens (typically non-safety-related) and strainers (typically safety related), including strainer backwash function. Review maintenance and operating history for the traveling screens and strainers to identify any adverse trends, such as repetitive shear pin failures. Also review history of trash rack blockage and trash rack cleaning frequency. Determine if intake fouling or blockage has resulted in any reactor power reductions. Review operating and abnormal procedures to determine whether guidance permits strainer bypass, even for temporary periods, for corrective maintenance. If so, then independently review licensee's evaluation of this condition regarding potential adverse impact on downstream structures, systems and components (SSCs), such as heat exchangers or coolers with small diameter tubes, because of fouling. For strainers, key inspection items may include check whether operators monitor strainer motor running amperage and compare readings when clogging is suspected, check how strainer backwash flow is verified, measured, or observed, and check that automatic strainer backwash is functional, if available. For those strainer systems which are

Issue Date: 02/18/22 12 71111.07 not safety-related, ensure procedures address service water operability if these strainers become clogged during a loss of power event.

2. Structural integrity of component mounts has not degraded (i.e., due to excessive corrosion). Review the periodic inspection program for the service water intake structure (recommended by GL 89-13). The inspection program should include silt monitoring and verification of continued component structural integrity, including underwater components (i.e., vortex preventer, trash rack, etc.).

3. Service water pump bay silt accumulation is monitored, trended, and maintained at an acceptable level.

4. Service water pump bay water level instruments are functional and routinely monitored. Assess operational controls to prevent excessive drawdown of the service water intake bay water level, with associated loss of service water pump suction because of clogging, fouling, or blockage of screens or racks. Operators should be able to identify lowering intake bay level before the Emergency Plan EAL value is reached. Abnormal operating procedure should direct sequential steps (e.g.,

sequential tripping of service water or circulating water pumps, or reducing reactor power) prior to reaching the EAL action level. Review should include indication, annunciation, and manual operator actions (operator response) for traveling screens, trash racks, and circulating water pumps.

5. Assess functionality during adverse weather conditions (e.g. algae bloom, grass intrusion, storm debris, icing, frazil ice formation, high temperatures, etc.). If the facility is in an area that is susceptible to frazil ice, then assess licensee's ability to identify or mitigate frazil ice conditions. Determine whether licensee has procedures to deal with adverse weather conditions. Coordinate the performance of this step with the performance of IP 71111.01, Adverse Weather Protection. This inspection should also ensure that UHS water temperature is monitored and has not exceeded licensing or design basis limiting values. Causal factors that have resulted in intake structure blockage have included environmental changes, such as storm and wind effects, aquatic life, frazzle ice, sand, silt, and crude oil from spills. Conditions which may allow frazil ice formation include, water temperature near freezing, low intake water level, windy conditions, and no ice cap on river or lake.

6. For underwater weir walls, intended to limit silt or sand intake, verify whether water could flow around, rather than over, the weir wall during periods of river or lake low water level. Verify that the licensee has evaluated the potential of silt introduction during periods of low flow/level or that the height of the wall is appropriate.

Issue Date: 02/18/22 13 71111.07 03.05 UHS Containment Device or Dam Verify that the UHS Containment Device or Dam remain capable of performing its intended safety functions.

Specific Guidance If the UHS containment device or dam is not licensee owned, ensure advance notice is provided to allow preparations for visual inspection when appropriate. Consideration for more frequent inspection should be made if there is known or suspected degradation.

a. For an above-ground UHS encapsulated by embankments, weirs or excavated side slopes, conduct walk-downs and/or review the licensees methods and results to verify that:

1. The toe of the weir or embankment is not experiencing unacceptable seepage of water and the crest of the dam is not showing unacceptable settlement. Erosion could lead to loss of structural integrity.

2. The rip rap protection placed on excavated side slopes remains in place, and vegetation along the slopes is maintained to prevent adverse impact on the embankment. Loss of shoreline protection can lead to a changing shoreline resulting in UHS capacity that is less than the design. Large vegetation, such as tree roots or burrowing animals can weaken the integrity of the embankments. Similarly, decayed tree roots can allow formation of a water channel in the embankment that weakens the integrity.

3. If available, review the results from any licensee or third-party dam inspections used to monitor the integrity or performance of the heat sink. The NRCs Dam Safety Officer may be able to provide additional guidance.

4. Verify sufficient reservoir capacity. Changing shorelines or sediment intrusion can reduce UHS capacity. Lessons learned from plant inspections include: degradation of the shoreline by vegetation growth can cause compacted clay to degrade and slump into the heat sink reducing capacity. Insufficient number of measurements taken of the depth of water may not identify significant debris or sediment build-up in the UHS.

b. For underwater UHS weirs, structures, or excavations, the inspection should identify settlement or movement indicating loss of structural integrity and/or capacity. The height of water over the crest of the weir should be constant in cases where the licensee takes these measurements to verify capacity. Review licensee inspection methods and results to verify that:

1. Any possible settlement or movement does not affect the structural integrity and/or capacity.

2. Sediment intrusion does not reduce capacity.

Issue Date: 02/18/22 14 71111.07 71111.07-04 REFERENCES IMC 0308, Attachment 2, Technical Basis for Inspection Program IMC 2515, Appendix A, Risk-Informed Baseline Inspection Program IP 71111.01, Adverse Weather Protection IP 71111.22, Surveillance Testing IP 71152, Problem Identification and Resolution.

EPRI NP-7552, Heat Exchanger Performance Monitoring Guidelines (Call the NRC Technical Library to get a copy of this if needed.)

EPRI TR-106438, Water Hammer Handbook for Nuclear Plant Engineers (Call the NRC Technical Library to get a copy of this if needed.)

TR-107397, Service Water Heat Exchanger Testing Guidelines TR-1003320, Supplemental Guidance for Testing and Monitoring Service Water Heat Exchangers EPRI 1009839, Heat Exchanger Single Tube Test Device TEMA Standards, Standards of the Tubular Exchanger Manufacturers Association ASME OM-S/G Part 21, Inservice Performance Testing of Heat Exchangers in Light-Water Reactor Power Plants NUREG 1275 Vol. 3, Operating Experience Feedback Report-Service Water System Failures and Degradations NUREG/CR-5865, Generic Service Water System Risk-Based Inspection Guide NUREG/CR-0548, Ice Blockage of Water Intakes Generic Letter 89-13, Service Water System Problems Affecting Safety-Related Equipment Generic Letter 91-13, Request for Info Related to the Resolution of GI 130, "Essential Service Water System Failures at Multi-Unit Sites Generic Letter 96-06, Assurance of Equipment Operability and Containment Integrity During Design-basis Accident Conditions Generic Letter 96-06, Assurance of Equipment Operability and Containment Integrity Supplement 1 During Design-basis Accident ConditionsBulletin 79-15, Deep Draft Pump DeficienciesBulletin 88-04, Potential Safety-Related Pump Loss [strong-pump to weak-pump interaction, and minimum flow requirements]

IN 80-07, Pump Shaft Fatigue Cracking

Issue Date: 02/18/22 15 71111.07 IN 93-68, Failure of Pump Shaft Coupling Caused by Temper Embrittlement IN 94-45, Potential Common-Mode Failure for Large Vertical Pumps IN 2004-07, Plugging of Safety Injection Pump Lubrication Oil Coolers with Lakeweed IN 2006-17, Recent Operating Experience of Service Water Systems due to External Conditions IN 2007-05, Vertical Deep Draft Pump Shaft and Coupling Failures IN 2007-06, Potential Common Cause Vulnerabilities in Essential Service Water Systems RG 1.27, Ultimate Heat Sink for Nuclear Power Plants RG 1.127, Inspection of Water-Control Structures Associated with Nuclear Power Plants See the following Web links for reference documents:

IHS Codes and Standards:

https://drupal.nrc.gov/tech-lib/35748 (non-public)

NRC Technical Library:

https://drupal.nrc.gov/tech-lib (non-public)

Cross Reference of Generic Communications with IP 71111.07:

https://drupal.nrc.gov/nrr/ope/33990 (non-public)

END

Issue Date: 02/18/22 Att1-1 71111.07 - Revision History for IP 71111.07 Commitment Tracking Number Accession Number Issue Date Change Notice Description of Change Description of Training Required and Completion Date Comment and Feedback Resolution Number (Pre-Decisional, Non-Public Information)

N/A 04/03/00 CN 00-003 Initial Issue - Revised Reactor Oversight Process N/A N/A 01/17/02 CN 02-001 Revised to differentiate between heat sinks and heat exchangers, including their independent performance requirements. In addition, inspection resource estimates and level of effort are revised to provide a band for more inspection flexibility.

None, N/A N/A ML051650399 06/06/05 CN 05-015 Revised to clarify inspection requirements and guidance for annual review and to add inspection guidance for determining the structural integrity of heat exchangers. In addition, minor changes have been made to the Cornerstones, Level of Effort, Inspection Completion, and References Sections of the inspection procedure.

None, N/A N/A 05/25/06 Researched commitments back four years -

none found.

None, N/A N/A N/A ML060460027 05/25/06 CN 06-013 Revised to incorporate lessons learned from ANO inspection regarding UHS dam integrity (report number 2005008); FB-937. Inspections of the UHS water reservoir is required every other biennial inspection.

Also, addressed FB-996 regarding inspections to prevent clogging of UHS equipment with sediment.

Other minor editorial comments also included.

None, N/A ML061290102

Issue Date: 02/18/22 Att1-2 71111.07 Commitment Tracking Number Accession Number Issue Date Change Notice Description of Change Description of Training Required and Completion Date Comment and Feedback Resolution Number (Pre-Decisional, Non-Public Information)

N/A ML073050455 01/31/08 CN 08-005 Revised to change biennial portion of this inspection procedure to triennial inspection periodicity based on 2007 ROP realignment results.

Revise to provide more specific inspection guidance, and to make it more effective and efficient.

Other minor editorial comments also included.

None, N/A ML080290277 N/A ML082970641 03/23/09 CN 09-010 Revised to provide more specific inspection guidance. Other minor editorial comments also included.

None, N/A ML090130171 N/A ML092300324 02/02/10 CN 10-004 Changed samples from 2-3 to 2-4 on Triennial Inspection. See 2009 ROP Realignment Results (ML092090312). Revised procedure to clarify sample requirements and add additional guidance.

None, N/A N/A 71111.07-1438 ML093380140 N/A ML100820347 07/06/10 CN 10-015 Added additional sample selection guidance.

None, N/A ML101740062 71111.07-1476 N/A ML16161A056 12/08/16 CN 16-032 Revised to incorporate aging management programs. Revised text to clarify inspection requirements versus guidance (should and shall), to address recommendations from OIG 16-A-12 audit.

None, N/A ML16162A010 71111.07-2059 ML16160A006 71111.07-2185 ML16160A008

Issue Date: 02/18/22 Att1-3 71111.07 Commitment Tracking Number Accession Number Issue Date Change Notice Description of Change Description of Training Required and Completion Date Comment and Feedback Resolution Number (Pre-Decisional, Non-Public Information)

N/A ML19291A214 10/21/20 CN 20-053 Major revision and reissue (no redline).

Relocated optional requirements to the guidance section to better align with IMC 2515, Section 8.04, sample completion requirements.

Eliminated need to perform redundant UHS Containment Device or Dam inspections at sites already receiving dedicated and focused inspections. Added AP1000 sample requirements. Reformatted to conform to IMC 0040.

None ML19316B054 (2019)

ML20233A519 (2020)

N/A ML22024A114 02/18/22 CN 22-004 Restored and clarified sample selection guidance for heat exchanger/sink/UHS in the General Guidance Section that was inadvertently removed from the preceding revision.

None N/A