3F1008-05, Nine Month Response to NRC Generic Letter 2008-01, Managing Gas Accumulation in Emergency Core Cooling Decay Heat Removal, and Containment Spray Systems.

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Nine Month Response to NRC Generic Letter 2008-01, Managing Gas Accumulation in Emergency Core Cooling Decay Heat Removal, and Containment Spray Systems.
ML082890555
Person / Time
Site: Crystal River Duke Energy icon.png
Issue date: 10/13/2008
From: Young D
Progress Energy Florida
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
3F1008-05, GL-08-001, TAC MD7816
Download: ML082890555 (21)
v • d • e


Text

0'Progress Energy Crystal River Nuclear Plant Docket No. 50-302 Operating License No. DPR-72 Ref: 10 CFR 50.54(f)

October 13, 2008 3F1008-05 U.S. Nuclear Regulatory Commission Attn: Document Control Desk 11555 Rockville Pike Rockville, Maryland 20852

Subject:

Crystal River Unit 3 - Nine Month Response to NRC Generic Letter 2008-01, "Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems"

References:

1. Generic Letter 2008-01 dated January 11, 2008, "Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems"
2. Letter from Crystal River Unit 3 to NRC, "Three Month Response to NRC Generic Letter 2008-01, Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems," dated May 8, 2008
3. Letter from NRC to Crystal River Unit 3 dated September 25, 2008, "Generic Letter 2008-01, "Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems," Proposed Alternative Course of Action (TAC NO. MD7816)"

Dear Sir:

The Nuclear Regulatory Commission (NRC) issued Generic Letter (GL) 2008-01, "Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems," (Reference 1), to request that each licensee evaluate the licensing basis, design, testing, and corrective action for the Emergency Core Cooling Systems (ECCS), Decay Heat Removal (DHR) System, and Containment Spray System, to ensure that gas accumulation is maintained less than the amount that challenges operability of these systems, and that appropriate action is taken when conditions adverse to quality are identified.

GL 2008-01 requested each licensee to submit a written response in accordance with 10 CFR 50.54(f) within nine months of the date of the GL to provide the information summarized below:

(a) A description of the results of evaluations that were performed pursuant to the requested actions; (b) A description of all corrective actions, including plant, programmatic, Progress Energy Florida, Inc..

Crystal River Nuclear Plant 15760 W. Powerline Street Crystal River, FL 34428

U.S. Nuclear Regulatory Agency 3F1008-05 Page 2 of 4 procedure, and licensing basis modifications that were determined to be necessary to assure compliance with the quality assurance criteria in Sections III, V, XI, XVI, and XVII of Appendix B to 10 CFR Part 50 and the licensing basis and operating license as those requirements apply to the subject systems; and, (c) A statement regarding which corrective actions were completed, the schedule for completing the remaining corrective actions, and the basis for that schedule.

Florida Power Corporation (FPC), doing business as Progress Energy Florida, Inc., hereby provides the requested nine month response to GL 2008-01 for the Crystal River Unit 3 Nuclear Plant (CR-3) as Attachment 1.

Reference 2 was submitted by FPC to document the CR-3 position that all information requested by GL 2008-01 would not be provided by the requested due date (October 11, 2008) as inaccessible piping would be unavailable for inspection until Refueling Outage 16 (R16),

scheduled to start in September 2009.

Reference 3 was issued by the NRC to document the acceptance of the three month response to Generic Letter 2008-01 and to provide clarifications and request specific information be provided with the nine month response to Generic Letter 2008-01.

In summary, FPC has concluded that the subject systems/functions at CR-3 are in compliance with the Technical Specification definition of Operability, i.e., capable of performing their intended safety function and that CR-3 is currently in compliance with 10 CFR 50. Appendix B, Criterion III, V, XI, XVI and XVII, with respect to the concerns outlined in GL 2008-01 regarding gas accumulation in the accessible portions of these systems/functions. Additionally, FPC has confidence that the currently inaccessible piping sections are also sufficiently full of water, based on drawing reviews and operating history, and that the scheduled walkdowns are confirmatory in nature. The ECCS, DHR and Containment Spray Systems will continue to remain capable of performing their safety functions.

Regulatory commitments are identified in Attachment 2.

If you have any questions regarding this submittal, please contact Mr. Daniel Westcott, Supervisor, Licensing and Regulatory Programs at (352) 563-4796.

Sincerely, Dale E. Young Vice President Crystal River Nuclear Plant DEY/par

U.S. Nuclear Regulatory Agency 3F1008-05 Page 3 of 4 : Nine Month Response to NRC Generic Letter 2008-01, "Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems" : List of Regulatory Commitments xc: NRR Project Manager Regional Administrator, Region II Senior Resident Inspector

U.S. Nuclear Regulatory Agency 3F1008-05 Page 4 of 4 STATE OF FLORIDA COUNTY OF CITRUS Dale E. Young states that he is the Vice President, Crystal River Nuclear Plant for Florida Power Corporation, doing business as Progress Energy Florida, Inc.; that he is authorized on the part of said company to sign and file with the Nuclear Regulatory Commission the information attached hereto; and that all such statements made and matters set forth therein are true and correct to the best of his knowledge, information, and belief.

Dale E. Young Vice President Crystal River Nuclear Plant The foregoing document was acknowledged before me this /3 day of

,2008, by Dale E. Young.

Signature of Notary Public orasa. p

  • I Name of Notary Public)

Personally ExProduced Known -OR- Identificationa___NOW

PROGRESS ENERGY FLORIDA, INC.

CRYSTAL RIVER UNIT 3 DOCKET NUMBER 50-302 LICENSE NUMBER DPR-72 ATTACHMENT 1 Nine Month Response to NRC Generic Letter 2008-01, "Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems"

U.S. Nuclear Regulatory Commission Attachment 1 3F1008-05 Page 1 of 14 NINE MONTH RESPONSE TO GENERIC LETTER 2008-01 This Attachment contains the Crystal River Unit 3 (CR-3) nine month response to NRC Generic Letter (GL) 2008-01, "Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems," dated January 11, 2008. In GL 2008-01, the NRC requested "that each addressee evaluate its Emergency Core Cooling Systems (ECCS), Decay Heat Removal (DHR) System, and Containment Spray System licensing basis, design, testing, and corrective actions to ensure that gas accumulation is maintained less than the amount that challenges operability of these systems, and that appropriate action is taken when conditions adverse to quality are identified."

The following information is provided in this response:

a) A description of the results of evaluations that were performed pursuant to the requested actions (see Section A of this Attachment),

b) A description of the corrective actions, including plant programmatic, procedure, and licensing basis modifications that were determined necessary to assure compliance with the quality assurance criteria in Sections III, V, XI, XVI, and XVII of Appendix B to 10 CFR Part 50 and the licensing basis and operating license with respect to the subject systems (see Section B of this Attachment), and c) A statement regarding which corrective actions have been completed, the schedule for completing the remaining corrective actions, and the basis for that schedule (see Section C of this Attachment).

The following systems were determined to be in the scope of GL 2008-01 for CR-3:

" Emergency Core Cooling System (ECCS) (High Pressure Injection, Low Pressure Injection, and Core Flood)

SECTION A - EVALUATION RESULTS Licensin2 Basis Evaluation The CR-3 licensing basis was reviewed with respect to gas accumulation in the ECCS, DH, and BS systems. This review included the Improved Technical Specifications (ITS), ITS Bases, Final Safety Analysis Report (FSAR), responses to NRC generic communications, Regulatory Commitments, and License Conditions.

1. Summary of the Licensing Basis Review The above documents and regulatory commitments were evaluated for compliance with applicable regulatory requirements. The CR-3 licensing basis is mostly silent on the subject of gas intrusion or gas accumulation into these systems. Most of the topics and available information that are related to noncondensable gas volumes impacting the performance of the ECCS, the DH System, or BS System are specific to losing decay heat removal capability during mid-loop operations. There were no documents identified

U.S. Nuclear Regulatory Agency Attachment 1 3F1008-05 Page 2 of 14 during the licensing basis search, that were specific to gas accumulation in the ECCS or voiding of the ECCS other than Significant Operating Experience Report (SOER) 97-01.

The response to SOER 97-01 provided assurance that the ECCS system would not experience any significant voiding in the suction piping to the ECCS pumps. The response was based on plant operating history and System Engineering walkdown evaluations.

There is currently no CR-3 ITS requirement to maintain or verify that the ECCS, DH, or BS piping is full of water. The CR-3 FSAR does not claim that the pumps and system piping are maintained full of water.

2. Changes That are Required Based on Review of the Licensing Basis Examples of Corrective Actions and commitments associated with the CR-3 licensing basis review are:

a) Quarterly monitoring will be developed and implemented to ensure that the ECCS, DH, and BS suction and discharge piping Will be maintained sufficiently full of water to ensure that the systems can reliably perform their intended functions.

The monitoring will include a requirement for periodic verification (every 92 days) that the ECCS, DH, and BS piping will be maintained sufficiently full of water by a combination of Ultrasonic Testing (UT), and venting as deemed necessary, of locations identified to be potentially susceptible to gas intrusion. UT results will be trended. Condition reports will be initiated for any gas volumes exceeding acceptance criteria; initially the criteria will be no accumulated gas, pending development of location specific acceptance criteria. The 92 days has been determined to be acceptable based on previous CR-3 operating history that has demonstrated a very low probability of gas intrusion of a magnitude sufficient to impact the safety function of the systems. Additionally, if maintenance activities breach the ECCS, DH, or BS system boundary, a UT will be performed as deemed necessary to verify the respective system(s) are sufficiently filled prior to return to service.

These Corrective Actions will be completed on 1/31/2009. Preventative Maintenance activities have been generated which will provide direction to implement interim monitoring until the procedure/program changes are implemented.

b) ITS improvements are being addressed by the Technical Specifications Task Force (TSTF) to provide an approved TSTF Traveler for making changes to individual licensee's Technical Specifications related to the potential for unacceptable gas accumulation. The development of the TSTF Traveler relies on the results of the evaluations of a large number of licensees to address the various plant designs.

FPC is continuing to support the industry and Nuclear Energy Institute (NEI) Gas Accumulation Management Team activities regarding resolution of generic ITS changes via the TSTF Traveler process. Within nine months after NRC approval of the TSTF Traveler, FPC will evaluate its applicability to CR-3, and evaluate

U.S. Nuclear Regulatory Agency Attachment 1 3F1008-05 Page 3,of 14 adopting the TSTF Traveler to supplement the current ITS requirements.

c) Other longer term activities pertaining to gas accumulation, such as Pressurized Water Reactor Owners Group (PWROG) activities, are being tracked under the CR-3 Nuclear Task Management process.

Design Evaluation The CR-3 design basis was reviewed with respect to gas accumulation in the ECCS, DH, and BS systems. This review included Design Basis Documents, Calculations,. and Vendor Technical Manuals.

1. Summary of the Design Basis Review Design Basis documentation was reviewed and the results verified there are no periodic monitoring or venting requirements for the ECCS, DH, or BS systems. Standard fill and vent evolutions; after system drain down and refill for maintenance, are performed in accordance with plant procedures. There are rno existing plant specific calculations that provide acceptance criteria for gas accumulation in piping or pumps. However, the pump vendor for the DH and BS pump designs has provided a pump specific acceptance limit for the pump passing accumulated gas of up to 5% void fraction at the pump inlet for short durations. This limit is. substantiated, by the PWROG efforts on determining acceptable void limits for pumps.

Since the ECCS; DH, and BS system rely on the static pressure from the Borated Water Storage Tank (BWST) or the Make-Up (MU) tank to maintain system pressure above atmospheric, there is no gas accumulation expected from inleakage through valve packing, pump seals, etc. It is possible for gas intrusion from higher pressure systems, such as Reactor Coolant (RC) or Core Flood, but levels and pressures in the various tanks and piping systems would indicate the problem. Gas intrusion during the ECCS or BS System operation is not expected via the Reactor Building (RB) sump either, as the sump strainer and trash grating are configured to minimize both high differential pressure and vortexing.

The. CR-3 configuration for the ECCS, DH system, and the. BS system includes maintaining the pump suction isolation valves open such that there is an open flow path from the BWST through the pump and up to the discharge isolation valve. This flow path places the static head of the BWST on the systems and maintains a system pressure at standby greater than atmospheric. This configuration has been maintained since April 1999, and no symptoms of gas accumulation in either the pump suction or discharge have manifested themselves during that time.

  • The primary gas intrusion risk occurs when the system or portions of the system are isolated and drained. During the fill and vent evolution, most of the gas is eliminated and any remaining gas is swept out of the system or back into either the BWST or the MU tank.

The only piping maintained in a voided condition in the ECCS, DH system or the BS system is the piping downstream of the BS pump discharge isolation valves and the DH

U.S. Nuclear Regulatory Agency Attachment 1 3F1008-05 Page 4 of 14 piping from the RB sump to the normally closed sump isolation valves. The BS discharge piping is left empty by design and is not a concern with respect to a water hammer event as the far end is open spray nozzles. Implementation of the PWROG methodology described in Fauske and Associates, Inc., calculation number FAI-08/78, demonstrated the acceptability of this configuration at CR-3. The DH suction piping from the RB sump to the sump isolation valves is also voided during normal plant operation. This piping becomes filled with water as the sump and lower RB elevation begin to flood with post-Loss of Coolant Accident (LOCA) inventory. The suction lines slope upward toward the RB sump, therefore providing a vent path during fill-up. The earliest that the DH and BS systems are aligned to the RB sump is >20 minutes, giving ample time for the suction piping to fill prior to use.

Engineered Safeguards (ES) actuation is based on high RB Pressure or low RCS pressure setpoints. Initial suction for High Pressure Injection (HPI), Low Pressure Injection (LPI),

and BS will be from the BWST. One train of the MU system is automatically realigned to provide the HPI function upon ES actuation while the LPI system, the BS system, and the other train of MU have their suction source already aligned while in standby configuration. Upon reaching the low level transfer point in the BWST, the suction to the HPI pumps is transferred to the discharge of the LPI pumps, and suction to the BS and LPI pumps is transferred to the RB sump. The suction valves from the RB sump are opened prior to closing the suction valves from the BWST, providing a constant suction source. The swap over to the RB sump is expected to be completed before the BWST level decreases to less than or equal to 7 feet.

Gas ingestion from the BWST is not a concern during the injection phase of the accident.

as there is no potential for vortex development during the ECCS pump suction transfer sequence. The analysis used the Reddy/Pickford methodology, which is recognized as an acceptable methodology for evaluating the potential for vortex formation.

In response to GL 2004-02, "Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized-Water Reactors," new RB sump strainers have been installed at CR-3. Following insulation replacement activities in Refueling Outage 16 (R16) in Fall 2009, the maximum strainer head loss due to postulated post-LOCA debris accumulation is predicted to be less than 0.10 foot of water column. Since the maximum head loss across the strainer is less than the submergence head, production of water vapor or gas evolution across the strainer due to the strainer pressure drop is not expected to occur, even when pumping saturated water. In the interim, training has been completed and procedures are in place regarding the recognition of sump blockage and subsequent actions, such as backwashing, that can be taken to reduce sump strainer pressure drop. Resolution of sump performance issues and tracking of insulation replacement are being addressed under the GL 2004-02 project.

The potential for vortex formation during RB sump recirculation was evaluated as part of the sump design change implemented to address GL 2004-02. This evaluation concluded that the replacement strainer design features offer adequate protection to prevent vortex formation under the most limiting conditions. There is adequate submergence for the strainer as well as a trash grating above the strainer to preclude vortexing.

Restrictions in maximum flow rates also help prevent vortex effects during shutdown cooling operations at reduced RCS inventory. Additionally, control room operators are

U.S. Nuclear Regulatory Agency Attachment 1 3F1008-05 Page 5 of 14 sensitive to the potential for DH vortexing via routine training and have both heightened awareness and procedural guidance during this evolution. Assisting the control room operators. is an adjustable low current alarm and a low flow alarm for the DH system.

These alarms are procedurally controlled.

Gas intrusion is not expected in the DH drop line as the system contains four isolation valves in series, minimizing the potential for any leakage from the RCS to the DH suction piping. There is no defined allowable leakage for these valves, however, each valve is equipped with a motor-operator and the valves are periodically inspected as part of the GL 89-10, "Safety-Related Motor-Operated Valve Testing and Surveillance," program and stroke tested as required by the CR-3 Inservice Test Program. Each train of the DH system discharge piping is separated from the Core Floodsystem by a check valve and a normally closed motor-operated gate Valve. The allowable back leakage rate for the check valves is 5 gpm. A leakage criterion used for boundary valve testing controls the allowable leakage and reduces the potential for gas intrusion.

FPC does not have any existing evaluations or analyses performed for CR-3 that address gas accumulation in the reactor core. However, the PWROG qualitatively evaluated the impact of noncondensable gases entering the RCS on the ability of the post-accident core cooling functions of the RCS. This is discussed further in Section 2.d below. Recent UTs performed have verified that the ECCS discharge piping outside containment contains no significant gas voiding.

The CR-3 design change screening criteria currently requires engineering personnel to determine if a proposed design change could create a possible water haimmer condition or

,could affect the amount of gas contained in a piping system. These criteria provide a barrier to design changes inadvertently increasing the potential for gas intrusion or accumulation.

Corrective. actions identified from the design basis document reviews are as follows:

1. FPC will develop an acceptance criterion for the maximum allowable void volume that will not challenge ECCS, DH, and BS System operability.

These acceptance criteria are expected to be developed by 12/31/09. FPC believes that recent plant specific operating history demonstrates that the accumulation of significant amounts of noncondensable gases is a low probability event, and while additional effort to reduce the probability further is warranted, immediate corrective action is not required.

2. FPC. will perform quarterly monitoring on identified piping vulnerable to gas intrusion from high to low pressure interfaces as discussed in the Licensing Basis review corrective action summary. p
2. New Gas Volume Acceptance Criteria Location-specific void volume acceptance criteria have generally not been established.

As an alternative, any identified gas voids are entered into the. CAP where they are individually evaluated for impact on system operability. Acceptance criteria will be developed for locations potentially susceptible to gas accumulation to preclude the need for entering the CAP. Until such acceptance criteria are developed, the CAP will be used to disposition discovered voids. Recently published industry guidance will be considered when either evaluating operability or establishing acceptance criteria. This guidance,

U.S. Nuclear Regulatory Agency Attachment 1 3F1008-05 Page 6 of 14 which is described below, will be supplemented as necessary when evaluating locations/conditions not covered by the industry guidance and to ensure that all relevant limitations are assessed.

a) Pump suction piping The interim allowable gas accumulation in the pump suction piping is based on limiting the gas entrainment to the pump after a pump start. A PWROG program established interim pump gas ingestion limits to be employed by the member utilities.

The interim criteria address pump mechanical integrity only and are as follows:

Single-Stage Multi-Stage Multi-Stage Stiff Shaft Flexible Shaft Steady-State 2% 2% 2%

Transient 5% for 20 sec. 20% for 20 sec. 10% for 5 sec.

QB.E.P. Range 70%- 120% 70%- 140% 70%- 120%

QBEP is the best efficiency pump flow rate These conservative criteria will be applied in support of system operability determinations and development of interim acceptance criteria until further data either substantiates the values or supports a change. These criteria, used in conjunction with other factors such as Net Positive Suction Head Required, duration of gas flow, and accidents for which the system is credited, provide a basis for system operability.

b) Pump discharge piping susceptible to pressure pulsation A joint PWROG program evaluated pump discharge piping gas accumulation. Gas accumulation in the piping downstream of the pump to the first closed isolation valve will result in amplified pressure pulsations after a pump start. A method for determining the acceptability of a given configuration was developed. The method uses plant specific information for piping restraints and relief valve setpoints to determine acceptable gas void volumes such that relief valve lifting does not occur and pipe loading is within acceptable limits. This, or similar methodology will be applied in support of individual system operability, determinations and development of acceptance 'criteria.

c) Pump discharge piping not susceptible to pressure pulsation A PWROG program provides methodologies that can be used to evaluate the piping response in the presence of accumulated gas for the BS piping downstream of the normally closed isolation valve as the riser and spray header are filled.

The PWROG methodology for BS evaluates the piping response as the BS header is filled and compares the potential force imbalances with the weight of the water filled piping. A CR-3 evaluation performed, using this methodology, concluded that the net force resulting from the pressurization of the BS header during the filling transient is a small fraction of the dead weight of the filled piping, and therefore is well within the margin of the pipe hangers.

d) RCS allowable gas ingestion The PWROG qualitatively evaluated the impact of noncondensable gases entering the RCS on the ability of the post-accident core cooling functions of the RCS. This evaluation assumed that 5 cubic feet of noncondensable gas at 400 psia was present in

U.S. Nuclear Regulatory Agency Attachment 1 3F1008-05 Page 7 of 14 the HPI discharge piping concurrent with 5 cubic feet of noncondensable gas at 100 psia in the LPI discharge piping. The qualitative evaluation concluded that these quantities. of gas will not prevent the ECCS from performing its core cooling function.

CR-3 will use these gas volumes in support of system operability determinations and development of acceptance criteria. A procedure revision request has been submitted for the applicable procedure.

3. Result of System Drawing Reviews Locations potentially susceptible to gas accumulation include isolated branch lines, valve bodies/bonnets, heat exchangers, improperly sloped piping, or locations upstream of components in horizontal lines (i.e., orifice plates and reducers).

Piping isometric drawing and/or piping arrangement drawings were reviewed to identify locations potentially susceptible to gas accumulation. Several drawings were modified to develop an Engineering aid to support detailed system walkdowns. These documents were simplified isometric drawings that contained only the information considered necessary by the lead Engineer (i.e., pipe slope, vent location or any other concern that could trap or contain an accumulation of gas) to support the walkdown scope.

Locations identified as potentially susceptible to gas accumulation are:

  • BS discharge piping downstream of the branch connection to the BWST full flow return line and upstream of the outboard containment isolation valves. This piping cannot be vented since no vent valves are installed at the high points
  • A small portion of the RB sump piping between the containment isolation valves and the downstream vent valves
  • MU system pump discharge piping segment due to an inverted U. configuration and no high point vent valve
  • Several locations in the DH and MU systems where the vent valve is located on the side of an elbow, not the high point
  • DH pump 3" recirculation line for both A and B pumps
  • Incorrectly sloped horizontal pipe sections in the MU, DH, and BS systems
  • Pipe segments below the DH purification isolation valves The potential for gas accumulation within valve bodies and valve bonnets has been evaluated for all valves within the systems under review. CR-3 has concluded that the small volumes of unventable gas accumulations within the valves do ýnot challenge operability since only a small fraction of the gas (if any) can be drawn into the active flow stream at any time.
4. Results of Plant Walkdowns Walkdowns of piping within the scope of the GL, that is accessible during normal operation, have been completed. Piping downstream of the normally closed BS pump discharge motor-operated containment isolation valve was excluded from the walkdown since this piping is normally empty and, therefore, does not require venting to ensure it is sufficiently full of water. Additionally, there is a segment of piping from the RB sump to

U.S. Nuclear Regulatory Agency Attachment 1 3F1008-05 Page 8 of 14 the isolation valves in each DH train that is inaccessible and was also excluded. There is also an inaccessible horizontal section of BWST suction line in each DH train that is outside of the Auxiliary Building, but completely protected by missile shields. Drawing reviews have provided confidence that these inaccessible locations are not operability concerns due to piping slope and/or periodic testing results.

The walkdowns were conducted to ensure that design drawings accurately reflected as-built conditions, particularly with respect to gas accumulation potential. The walkdowns also looked for details that may not be included on drawings such as whether vents are properly located (e.g., at top-dead-center of horizontal piping, at local high point of nominally horizontal piping) and whether nominally horizontal piping was actually sloped. To assess the latter, the slope of nominally horizontal piping runs was measured to determine if any unvented local high points existed where gas could potentially be trapped or accumulate.

The drawing reviews and supporting piping walkdowns identified approximately 46 locations potentially susceptible to gas accumulation. Ultrasonic testing at these locations has been performed in order to detect the presence of any gas voids. The results of the ultrasonic tests performed at these locations revealed no significant gas accumulation in any of the susceptible locations.

One void was discovered upstream of the BS system discharge isolation valve, but downstream of the full flow recirculation branch line back to the BWST. This condition was determined to not impact operability. The size of the voiding was evaluated and found to not adversely impact the function of the BS system.

Another very small void was discovered in a highpoint on the MU pump discharge header (inverted U), where an abandoned tee is installed. This gas void has been exposed to full flow HPI pump testing during each refueling outage with no adverse indications or consequences. This location is also exposed to full MU pump discharge flow during normal operations. An evaluation has shown that the location of this void is fixed since it has not been displaced either by full HPI flow during refueling interval testing or during normal plant operations.

It is understood by CR-3 that some areas potentially susceptible to gas accumulation may have been full at the time of UT, but may have contained voids immediately after fill and vent that were subsequently swept away during normal system operation or periodic pump testing. This concern will be addressed by improved system fill and vent practices, which are discussed later in this response.

CR-3 will complete the detailed walkdowns and ultrasonic examinations of inaccessible piping at locations susceptible to gas accumulation for systems within the scope of the GL prior to startup from the next refueling outage (R16).

5. Identified New and Relocated Vent Valves Based on the drawing reviews, walkdowns, and subsequent evaluation of unvented high points, the following new vent locations have been identified:

U.S. Nuclear Regulatory Agency Attachment 1 3F1008-05 Page 9 of 14

  • DH minimum flow recirculation lines (2 total)
  • Downstream of the RCS to DH common suction line containment isolation valve (1 total)
  • Upstream of the BS containment isolation valves, downstream of the recirculation header to the BWST(2 total)
  • MU discharge header (inverted U) (1 total)
  • Below the DH isolation valves to the MU and Purification System, discharge side (2 total)
  • Below the DH isolation valves to the MU and Purification System, suction side (2 total)
  • Downstream of the common MU suction line check valve (1 total)
  • Below MU Pump.B manual suction isolation valve (1 total)

Based on confirmatory walkdowns, the following existing vent valves will be relocated to the piping high point: MU system discharge piping vent valves located on the mid-plane of an elbow (2 total).

Slope discrepancy corrections via the adjustment of existing piping supports will be attempted on several pipe sections on the suction side of the MU pumps due to the relatively small magnitude of the out-of-slope conditions in combination with the lengths of the lines. Based on the results of this effort, additional locations for vent valve installation may be identified.

All new and relocated vent valves are considered to be enhancements to the systems and are not required to ensure continued operability of the system. These vent valves will be installed prior to breaker closure following R16. Performance of UT on these locations has revealed no significant gas accumulation. Should any of these piping segments be drained and refilled prior to the next refueling outage, UT will be performed following fill and vent to assure sufficiently full conditions prior to returning the system to service.

.6. Fill and Vent Activity and Procedure Review Results In addition to the vent valve enhancements discussed above, the fill and vent process review identified several procedure enhancements.

Building Spray system: Several enhancements were identified that could prevent leaving a void in a pipe segment. These include duration of venting activities and proper sequencing of the fill and vent activity.

Decay Heat system: Several enhancements were identified that could prevent leaving a void in a pipe segment. These include duration of venting activities and proper sequencing of the fill and vent activity.

MU system: Several enhancements were identified that could prevent leaving a void in a pipe segment. These include duration of venting activities and proper sequencing of the fill and vent activity.

Procedures will be enhanced to provide additional detail where needed concerning venting sequence, venting duration, dynamic venting, etc., and to UT appropriate piping

U.S. Nuclear Regulatory Agency Attachment 1 3F1008-05 Page 10 of 14 locations following fill and vent as deemed necessary to ensure piping is sufficiently full prior to return to service. Entry into the Corrective Action Program will be expected for any void discovered after venting. Procedure revision enhancements identified above will be completed prior to their next use, but no later than 12/31/2009.

No new site specific procedures have been identified as required to perform an effective fill and vent process.

7. Potential Gas Intrusion The most probable gas intrusion method is inadequate fill and vent evolutions where noncondensable gases are allowed to remain in the pipe. Previous fill and vent processes did not utilize UT to verify a near water solid condition and the current fill and vent procedures do not provide sufficient guidance to assure the system is sufficiently filled.

As noted above, procedure revisions to existing fill and vent processes will address these concerns.

Another credible, but much-lower probability, method of gas intrusion is through the high to low pressure interfaces, leaking past multiple valves. The higher pressure liquid then has gas come out of solution when exposed to the lower pressure side. This potential exists with the DH drop line from the RCS B hot leg and with the LPI piping connected to the Core Flood Nozzles. This condition is not expected to occur without Operations knowledge due to one or more of the following: possible relief valve lifting; unexplained level increases in the BWST; decreasing level in a Core Flood Tank; and/or a mismatch in the RCS water balance calculation. However, periodic UT will be performed at these susceptible locations to verify gas is not accumulating.

Other sources of gas intrusion, such as vortexing, elevation changes, temperatures above saturation temperature, or pressure drop across the RB sump screen have been evaluated to be highly unlikely. No keep fill systems are used; however, all ECCS, DH, and BS pump suctions are aligned either to the BWST or MU tank during standby operation, which maintains system pressure in all portions of the ECCS, DH, and BS systems above atmospheric pressure.

8. Industry Programs Ongoing industry programs are planned in the following areas which may impact the conclusions reached during the design evaluation of CR-3 relative to gas accumulation.

The activities will be monitored to determine if additional changes to the CR-3 design may be required or desired to provide additional margin.

  • Gas Transport in Pump Suction Piping The PWROG has initiated testing to provide additional knowledge relative to gas transport in piping. One completed program performed testing of gas transport in 6-inch and 8-inch piping. Another program is underway to perform additional testing of gas transport in 4-inch and 12-inch low temperature systems and 4-inch high temperature systems. This program will integrate the results of the 4-inch, 6-inch, 8-inch and 12-inch testing and develop a scaling model to address even larger diameter pipe.

U.S. Nuclear Regulatory Agency Attachment 1 3F1008-05 Page 11 of 14 Pump Suction Void Fraction Acceptance Criteria Long-term industry tasks were identified that will provide additional tools to address GL-2008-01 with respect to pump gas void ingestion tolerance limits.

Testing Evaluation

1. Testing Procedure Review At CR-3, there is currently no periodic venting or monitoring occurring for gas accumulation. There are no ITS Surveillance Requirements and no Surveillance Test procedures to perform this activity.
2. Procedures and Procedure Revisions As discussed in the Licensing Basis Evaluation section of this response, CR-3 will perform periodic UT, to ensure that the ECCS, DH and BS piping will be maintained sufficiently full of water to ensure that the systems can reliably perform their intended functions. Additionally, if maintenance activities breach the system boundary, a UT will be performed, as deemed necessary, prior to returning the system to service. Specific procedures will be revised to address fill and vent activities, and performance of UT to validate or quantify gas volumes. Entry into the Corrective Action Program will be expected for any void discovered. after venting. The procedures will be revised by 12/31/09 or first use, whichever is earlier.
3. Procedure Adequacy At CR-3, plant operating procedures provide guidance on fill and vent of the DH system.

There is also procedural guidance for start up during an outage and operation at decreased inventory conditions. There are similar procedures for the MU and BS systems.

Currently, there is no guidance on UT for verifying piping is sufficiently full. Periodic surveillance testing requires full flow testing back to the BWST which would sweep any accumulated gas out of the system. Plant operators are stationed near the pump to monitor its performance, and to terminate the test if unusual performance is detected.

Additionally, the control room operators have a low flow alarm for the DH, MU, and BS pumps, and a low amp alarm for the DH pumps. The control room operators monitor all running pumps for signs of cavitation as a good practice. The success of this methodology was demonstrated by the lack of discovery of any significant voiding in the accessible sections of the ECCS, DH, or BS systems via recent UT performance.

4. Procedure Reviews A review of plant procedures to verify that gas intrusion will not occur due to valve manipulations other than system alignments has been performed. No vulnerabilities have been identified that are considered significant and all enhancements identified have been entered in CAP.

U.S. Nuclear Regulatory Agency Attachment 1 3F1008-05 Page 12 of 14

5. Gas Void Detection and Documentation At CR-3, gas voids were not being actively searched for, other than by routine monitoring of pump performance. However, gas voids discovered by any means are entered into the Corrective Action Program for disposition and corrective action. All voiding discovered during the CR-3 GL 2008-01 walkdowns and performance of UT, was addressed through the CAP. In the future, following establishment of void size acceptance criteria, only those voids with volumes exceeding the applicable acceptance criteria will be entered into the CAP.

SECTION B - CORRECTIVE ACTIONS Corrective Actions Evaluation

1. Summary of the Corrective Action Program FPC's Corrective Action Program is used to document gas intrusion/accumulation issues as potential nonconforming conditions. Until an Engineering. evaluation is completed, the condition is a potential operability and/or reportability issue and the Control Room will be notified for their review/concurrence. CR-3 currently has a threshold value of zero identified voiding in the ECCS, BS and DH systems before initiating a condition report and entering it into the CAP. This threshold value will remain zero until formal acceptance criteria are established. Therefore, FPC's review concluded that issues involving gas intrusion/accumulation are properly prioritized and evaluated under the Corrective Action Program.
2. Explaining the CAP Entry Threshold The current and near term threshold value for entry into the CAP for identified gas voiding is zero. In other words, any and all identified voiding will be entered into the CAP. The condition will be considered as an Operability concern and will receive an Operations review. Engineering will be required to provide the technical basis for Operability decisions. The CAP performs trending of similar conditions such as gas voids.

Description of Necessary Corrective Actions The following corrective actions were determined to be necessary to assure compliance with the applicable regulations:

Complete walkdown and evaluation of all ECCS, DH, and Make-up system piping inside containment. This activity will be completed and a supplementary letter will be submitted within 90 days following the completion of Refueling Outage 16. Due to environmental conditions and other barriers precluding completion of these activities while online, these activities are scheduled for Refueling Outage 16. This activity was identified as a commitment in Reference 2.

U.S. Nuclear Regulatory Agency Attachment 1 3F1008-05 Page 13 of 14 SECTION C - CORRECTIVE ACTION SCHEDULE

1. Corrective Actions Completed CR-3 completed the walkdown of accessible ECCS,.DH, and BS System piping for void susceptibility, performed UT on identified locations, and assessed as-found results to have no impact on system operability.

CR-3 completed the evaluation of BS piping inside containment to demonstrate no potential waterhammer would cause damage. This is considered a corrective action that has been completed.

CR-3 has completed the review of procedures that could inadvertently cause voiding in the subject systems. No significant concerns were identified.

2. Corrective Actions that have not been Completed Implement performance of periodic UTs at locations identified as susceptible to gas intrusion. These inspections will be developed and implemented by 1/31/2009. Standard plant operating practice includes stationing an operator near the pump to be started during post maintenance testing and surveillance testing. One of the duties of the operator is to observe for unusual performance. ýAdditionally, control room operators observe the system instrumentation associated with the subject system for signs of unusual performance during system start up, which includes current oscillations, pump and system pressures and flow. This monitoring is considered to be a good practice. A low flow alarm is available to aid the operator on all three subject systems. High confidence exists that any noncondensable gas will be detected and the test terminated before any system damage will occur.

Install new vent valves and relocate existing vent valves as an enhancement. These valves will be installed in susceptible piping locations in order to simplify the work required during fill and vent evolutions. This activity will be completed prior to breaker closure following R16. Although some of the valves can be installed during online system outages, several cannot be installed until R16. These vents will allow for smaller boundaries to be used while performing system maintenance and are not required to demonstrate compliance with the design and license basis criteria within the scope of the Generic Letter. Additionally, this activity will assure the piping is sufficiently full without having to rely on sweeping any noncondensable gases into the BWST, MU tank, or RCS. The performance of recent UTs clearly demonstrated that any noncondensable gases are swept out of the systems during routine operation or testing.

System operating procedures will be enhanced to provide additional detail where needed concerning venting sequence, venting duration, dynamic venting, performance of UT, etc. This will be completed by 12/31/2009. All improvements to the procedures are considered enhancements since plant walkdowns and performance of UT on potentially susceptible locations have demonstrated that any noncondensable gases are removed during normal system operation or testing.

U.S. Nuclear Regulatory Agency Attachment 1 3F1008-05 Page 14 of 14 Procedures will be enhanced to UT appropriate piping locations following fill and vent to ensure piping is sufficiently full before being returned to service. This activity will be completed by 12/31/2009. This activity is considered to be an enhancement based on current operating practices and CR-3 operating history. CR-3 operating history demonstrates that CR-3 maintains insignificant volumes of noncondensable gases in the ECCS, DH and BS systems.

FPC will develop acceptance criteria for the maximum allowable void volumes that will not challenge ECCS, DH, and BS system operability. These analyses are expected to be completed by 12/31/09.

PROGRESS ENERGY FLORIDA, INC.

CRYSTAL RIVER UNIT 3 DOCKET NUMBER 50-302 / LICENSE NUMBER DPR-72 ATTACHMENT 2 List of Regulatory Commitments

U.S. Nuclear Regulatory Commission Attachment 2

  • Page 1 of 3F1008-05 1 LIST OF REGULATORY COMMITMENTS The following table identifies the complete list of actions committed to by Florida Power Corporation (FPC) relevant to Generic Letter 2008-01, "Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems." Any other actions discussed in the submittal represent intended or planned actions by FPC. They are described to the NRC for the NRC's information and are not regulatory commitments. Please notify the Supervisor, Licensing and Regulatory Programs of any questions regarding this document or any associated regulatory commitments.

Commitment Due Date Quarterly monitoring will be developed and implemented to ensure that the 1/31/2009 ECCS, DH, and BS suction and discharge piping will be maintained sufficiently full of water to ensure that the systems can reliably perform their intended functions.

The inspections will include a requirement for periodic verification (every 92 days) that the ECCS, DH, and BS piping will be maintained sufficiently full of water bya combination of Ultrasonic Testing (UT), and venting as deemed necessary, of locations identified to be potentially susceptible to gas intrusion. (high to lw pressure interfaces)

Additionally, should any maintenance activities breach the ECCS, DH, or BS System boundary, a UT will be performed as deemed necessary to verify the respective system(s) are sufficiently full prior to return to service.

Procedures will be enhanced to provide additional detail where needed Procedure concerning venting sequence, venting duration, dynamic venting, etc.; and revisions will be to UT appropriate piping locations following fill and vent as deemed completed by necessary, to ensure piping is sufficiently full prior to return.to service. 12/31/2009 -

FPC is continuing to support the industry and NEI Gas Accumulation 9 months after Management Team activities regarding resolution of generic ITS changes NRC approval of via the TSTF Traveler process. Within nine months after NRC approval of the TSTF the TSTF Traveler, FPC will evaluate its applicability to CR-3, and evaluate adopting the TSTF Traveler to supplement the current ITS requirements.

FPC will develop an acceptance criterion for the maximum allowable void 12/31/09 volume that will not challenge ECCS, DH, or BS System operability.

FPC will install the new vent valves and relocate existing vent valves as Installation will be discussed in the Design Evaluation section of this response. completed prior~to breaker closure following R16

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