ML13298A696
| ML13298A696 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 11/01/2013 |
| From: | Guzman R V Plant Licensing Branch II |
| To: | Batson S Duke Energy Carolinas |
| Guzman R V | |
| References | |
| EA-12-051, TAC MF0785, TAC MF0786, TAC MF0787 | |
| Download: ML13298A696 (27) | |
Text
UNITED NUCLEAR REGULATORY WASHINGTON, D.C. 20555-0001 November 1, 2013 Mr. Scott Batson Site Vice President Oconee Nuclear Station Duke Energy Carolinas, LLC 7800 Rochester Highway Seneca, SC 29672-0752 INTERIM STAFF EVALUATION AND REQUEST FOR ADDITIONAL INFORMATION
-OCONEE NUCLEAR STATION, UNITS 1,2 AND 3 REGARDING OVERALL INTEGRATED PLAN FOR RELIABLE SPENT FUEL POOL INSTRUMENTATION (ORDER NUMBER EA-12-051) (TAC NOS. MF0785, MF0786, AND MF0787)
Dear Mr. Batson:
On March 12, 2012, the U.S. Nuclear Regulatory Commission (NRC) issued Order EA-12-051, "Order Modifying Licenses with Regard to Reliable Spent Fuel Pool Instrumentation" (Agencywide Documents Access and Management System (ADAMS) Accession No. ML12054A679), to all power reactor licensees and holders of construction permits in active or deferred status. This Order requires the licensee to have a reliable indication of the water level in associated spent fuel storage pools capable of supporting identification of the following pool water level conditions by trained personnel:
(1) level that is adequate to support operation of the normal fuel pool cooling system, (2) level that is adequate to provide substantial radiation shielding for a person standing on the spent fuel pool operating deck, and (3) level where fuel remains covered and actions to implement make-up water addition should no longer be deferred.
By letter dated February 28, 2013 (ADAMS Accession No. ML 13086A095), Duke Energy Carolinas, LLC (Duke Energy, the licensee) provided the Overall Integrated Plan (OIP) for the Oconee Nuclear Station, Units 1, 2, and 3, describing how it will achieve compliance with Attachment 2 of Order EA-12-051.
By letters dated July 19, 2013 (ADAMS Accession No. ML 13207 A413) and August 26, 2013 (ADAMS Accession No. ML 13242A009), the licensee provided supplemental information.
The NRC staff has reviewed these submittals with the understanding that the licensee will update its OIP as implementation of the Order progresses.
With this in mind, the staff has included an interim staff evaluation with this letter to provide feedback on the OIP. The staff's findings in the interim staff evaluation are considered preliminary and will be revised as the OIP is updated. As such, none of the staff's conclusions are to be considered final. The enclosed interim staff evaluation provides preliminary NRC staff conclusions in areas where the licensee has provided sufficient information and identifies areas where additional information is needed. In order for the staff to review the final licensee's SFP instrumentation OIP and complete the staff evaluation, all the requested information must be provided no later than March 31, 2015, to ensure that any issues are resolved prior to the date by which the licensee S. Batson -must complete full implementation of Order EA-12-051.
The licensee should adjust its schedule for providing information to ensure that all this information is provided by the requested date. A final NRC staff evaluation will be issued after the licensee has provided the information requested.
If you have any questions regarding this letter, please contact me at 301-415-1030 or via e-mail at Richard.Guzman@nrc.gov.
Sincerely, Richard V. Guzman, Senior Project Manager Plant Licensing Branch 11-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-269, 50-270, and 50-287
Enclosure:
Interim Staff Evaluation and Request for Additional Information cc w/encls: Distribution via Listserv INTERIM STAFF EVALUATION AND REQUEST FOR ADDITIONAL BY THE OFFICE OF NUCLEAR REACTOR RELATED TO THE OVERALL INTEGRATED PLAN IN RESPONSE ORDER EA-12*051.
RELIABLE SPENT FUEL POOL DUKE ENERGY CAROLINAS. OCONEE NUCLEAR STATION. UNITS 1,2 AND DOCKET NOS. 50-269, 50-270 AND
1.0 INTRODUCTION
On March 12,2012, the U.S. Nuclear Regulatory Commission (NRC) issued Order EA-12-051, "Issuance of Order to Modify Licenses with Regard to Reliable Spent Fuel Pool Instrumentation" (Agencywide Documents Access and Management System (ADAMS) Accession No. ML 12054A679), to all power reactor licensees and holders of construction permits in active or deferred status. This Order requires, in part, that all operating reactor sites have a reliable means of remotely monitoring wide-range Spent Fuel Pool (SFP) levels to support effective prioritization of event mitigation and recovery actions in the event of a Beyond-Design-Basis (BOB) external event. The Order required all holders of operating licenses issued under Title 10 of the Code of Federal Regulations (10 CFR) Part 50, "Domestic Licensing of Production and Utilization Facilities," to submit to the NRC an Overall Integrated Plan (OIP) by February 28, 2013. By letter dated February 28,2013 (ADAMS Accession No. ML 13086A095), Duke Energy Carolinas, LLC (Duke Energy, the licensee) provided the OIP for Oconee Nuclear Station (ONS), Units 1, 2 and 3, describing how it will achieve compliance with Attachment 2 of Order EA-12-051 by fall 2015 for Units 1 and 2, and by spring 2016 for Unit 3. By letter dated June 21,2013 (ADAMS Accession No. ML 13171A301), the NRC staff sent a request for additional information (RAI) to the licensee.
The licensee provided supplemental information by letters dated July 19, 2013 (ADAMS Accession No. ML 13207A413) and August 26,2013 (ADAMS Accession No. ML 13242A009).
2.0 REGULATORY EVALUATION
Order EA-12-051 requires all holders of operating licenses issued under 10 CFR Part 50, notwithstanding the provisions of any Commission regulation or license to the contrary, to comply with the requirements described in Attachment 2 to this Order except to the extent that a more stringent requirement is set forth in the license. Licensees shall promptly start implementation of the requirements in Attachment 2 to the order and shall complete full implementation no later than two refueling cycles after submittal of the OIP or December 31, 2016, whichever comes first. Order EA-12-051 required the licensee, by February 28,2013, to submit to the Commission an OIP, including a description of how compliance with the requirements described in Attachment 2 of the Order will be achieved.
-Attachment 2 of Order EA-12-051 requires the license to have a reliable indication of the water level in associated spent fuel storage pools capable of supporting identification of the following pool water level conditions by trained personnel:
(1) level that is adequate to support operation of the normal fuel pool cooling system, (2) level that is adequate to provide substantial radiation shielding for a person standing on the SFP operating deck, and (3) level where fuel remains covered and actions to implement make-up water addition should no longer be deferred.
Attachment 2 of Order EA-12-051 , states that the SFP level instrumentation shall include the following design features: Instruments:
The instrumentation shall consist of a permanent, fixed primary instrument channel and a backup instrument channel. The backup instrument channel may be fixed or portable.
Portable instruments shall have capabilities that enhance the ability of trained personnel to monitor spent fuel pool water level under conditions that restrict direct personnel access to the pool, such as partial structural damage, high radiation levels, or heat and humidity from a boiling pool. 1.2 Arrangement:
The spent fuel pool level instrument channels shall be arranged in a manner that provides reasonable protection of the level indication function against missiles that may result from damage to the structure over the spent fuel pool. This protection may be provided by locating the primary instrument channel and fixed portions of the backup instrument channel, if applicable, to maintain instrument channel separation within the spent fuel pool area, and to utilize inherent shielding from missiles provided by existing recesses and corners in the spent fuel pool structure. Mounting:
Installed instrument channel equipment within the spent fuel pool shall be mounted to retain its design configuration during and following the maximum seismic ground motion considered in the design of the spent fuel pool structure. Qualification:
The primary and backup instrument channels shall be reliable at temperature, humidity, and radiation levels consistent with the spent fuel pool water at saturation conditions for an extended period. This reliability shall be established through use of an augmented quality assurance process (e.g., a process similar to that applied to the site fire protection program). Independence:
The primary instrument channel shall be independent of the backup instrument channel. Power supplies:
Permanently installed instrumentation channels shall each be powered by a separate power supply. Permanently installed and portable instrumentation channels shall provide for power connections from sources independent of the plant [alternating current (ac)] and [direct current (dc)] power distribution systems, such as portable generators or
-3 replaceable batteries.
Onsite generators used as an alternate power source and replaceable batteries used for instrument channel power shall have sufficient capacity to maintain the level indication function until offsite resource availability is reasonably assured. Accuracy:
The instrument channels shall maintain their deSigned accuracy following a power interruption or change in power source without recalibration. Testing: The instrument channel design shall provide for routine testing and calibration. Display: Trained personnel shall be able to monitor the spent fuel pool water level from the control room, alternate shutdown panel, or other appropriate and accessible location.
The display shall provide demand or continuous indication of spent fuel pool water level. Attachment 2 of Order EA-12-051 , states that the SFP instrumentation shall be maintained available and reliable through appropriate development and implementation of the following programs: Training:
Personnel shall be trained in the use and the provision of alternate power to the primary and backup instrument channels. Procedures:
Procedures shall be established and maintained for the testing, calibration, and use of the primary and backup spent fuel pool instrument channels. Testing and Calibration:
Processes shall be established and maintained for scheduling and implementing necessary testing and calibration of the primary and backup spent fuel pool level instrument channels to maintain the instrument channels at the design accuracy.
On August 29,2012, the NRC issued an Interim Staff Guidance document (the ISG), JLD-ISG-2012-03, "Compliance with Order EA-12-051, Reliable Spent Fuel Pool Instrumentation" (ADAMS Accession No. ML 12221A339), to describe methods acceptable to the NRC staff for complying with Order EA-12-051.
The ISG endorses, with exceptions and clarifications, the methods described in the Nuclear Energy Institute (NEI) guidance document NEI 12-02, Revision 1, "Industry Guidance for Compliance with NRC Order EA-12-051 , 'To Modify Licenses with Regard to Reliable Spent Fuel Pool Instrumentation,'" dated August 2012 (ADAMS Accession No. ML 12240A307).
Specifically, the ISG states: The NRC staff considers that the methodologies and guidance in conformance with the guidelines provided in NEI 12-02, Revision 1, subject to the clarifications and exceptions in Attachment 1 to this ISG, are an acceptable means of meeting the requirements of Order EA-12-051.
-3.0 TECHNICAL EVALUATION
3.1 Background
and Schedule Oconee Nuclear Station (ONS) has two separate SFPs, one shared by Units 1 & 2 and a separate pool for Unit 3. There are no gates or divisions that could create different levels within the shared Unit 1 and 2 pool. The licensee submitted its OIP on February 28, 2013. The OIP states that installation of the SFP level instrumentation at ONS will be completed by fall 2015, for Units 1 and 2, and by spring 2016, for Unit 3 based on the end of the second refueling outage for each unit following submittal of this integrated plan. The NRC staff has reviewed the licensee's schedule for implementation of SFP level instrumentation provided in its OIP. If the licensee completes implementation in accordance with this schedule, it would appear to achieve compliance with Order EA-12-051 within two refueling cycles after submittal of the OIP and before December 31,2016. 3.2 Spent Fuel Pool Water Levels Attachment 2 of Order EA-12-051 states, in part, that All licensees identified in Attachment 1 to this Order shall have a reliable indication of the water level in associated spent fuel storage pools capable of supporting identification of the following pool water level conditions by trained personnel:
(1) level that is adequate to support operation of the normal fuel pool cooling system [Level 1], (2) level that is adequate to provide substantial radiation shielding for a person standing on the SFP operating deck [Level 2], and (3) level where fuel remains covered and actions to implement make-up water addition should no longer be deferred [Level 3]. NEI 12-02 states, in part, that Level 1 represents the HIGHER of the following two points: The level at which reliable suction loss occurs due to uncovering of the coolant inlet pipe, weir or vacuum breaker (depending on the design), or The level at which the water height, assuming saturated conditions, above the centerline of the cooling pump suction provides the required net positive suction head specified by the pump manufacturer or engineering analysis.
In its OIP, the licensee stated that Level 1 is the indicated level greater than the point at which pump suction is presumed to be lost. This level is at elevation 837 feet (ft.) 6 inches (in.)
-In its letter dated July 19, 2013, the licensee stated, in part, that The normal SFP water level is Elevation (EI.) 840'-0". The SFP cooling pump suction piping submergence is lost when water level decreases below EI. 836'-0" (Point A). During normal operation, SFP cooling pumps are automatically tripped at EI. 837'-6" to protect against NPSH and vortex concerns.
However, as the SFP temperatures increase above normal, including temperatures that approach saturation conditions, the SFP cooling pump flow rates are procedurally controlled to prevent operation with potentially inadequate net positive suction head (NPSH) or vortex conditions based on engineering analysis.
Under these high temperature and reduced flow conditions, the limiting level which provides protection against inadequate NPSH or vortex conditions is EI. 840'-6", which is 6 inches above the normal SFP water level. Due to the design of the SFP suction piping, pump operation cannot be supported at all during saturation conditions in the pool. Thus, Point B for ONS can only be approximated by the point at which NPSH protection is provided, which varies dependent on SFP conditions.
Under normal conditions, Point B relates to EI. 837'-6", as provided in the overall integrated plan submitted February 28, 2013. But as SFP temperatures approach saturation, Point B relates to EI. 840'-6". Therefore, ONS will consider EI. 840'-6" as its "Level 1" datum due to it being higher that Point A, and higher than EI. 837'-6". Each channel will be capable of indicating any of these levels, as well as the other level datum required by I\IEI12-02
... In its letter dated July 19, 2013, the licensee provided a sketch showing the approximate location of the level sensor and the elevations identified as Levels 1,2 and 3. The NRC staff reviewed this sketch and notes that Level 1 is identified at an elevation of 840 ft. 6 in. The staff notes that this level is adequate for normal SFP cooling system operation and it is also adequate to ensure the required fuel pool cooling pump net positive suction head (NPSH). This level represents the higher of the two points described in NEI 12-02 for Level 1. NEI 12-02 states, in part, that Level 2 represents the range of water level where any necessary operations in the vicinity of the spent fuel pool can be completed without significant dose consequences from direct gamma radiation from the stored spent fuel. Level 2 is based on either of the following: 10 feet (+1-1 foot) above the highest point of any fuel rack seated in the spent fuel pools, or a designated level that provides adequate radiation shielding to maintain personnel radiological dose levels within acceptable limits while performing local operations in the vicinity of the pool. This level shall be based on either plant-specific or appropriate generic shielding
-6 calculations, considering the emergency conditions that may apply at the time and the scope of necessary local operations, including installation of portable SFP instrument channel components.
In its alP, the licensee stated that Level 2 is the indicated level greater than 10ft. above the highest point of any fuel storage racks. This level is at elevation 826 ft. 6 in. for Units 1 and 2 and elevation 826 ft. 4 in. for Unit 3. In its letter dated July 19, 2013, the licensee provided a sketch showing the elevations identified as Levels 1, 2 and 3. The NRC staff reviewed this sketch and notes that Level 2 is identified at an elevation of 826 ft. 6 in. for the Units 1 and 2 SFP. The staff also notes that the Level 2 elevation for the Unit 3 SFP is not identified in the sketch. The staff will address this request in RAI #1. NEI 12-02 states, in part, that Level 3 corresponds nominally (Le., +/-1 foot) to the highest point of any fuel rack seated in the spent fuel pool. Level 3 is defined in this manner to provide the maximum range of information to operators, decision makers and emergency response personnel.
In its alP, the licensee stated that Level 3 is the indicated level at the highest point of any fuel storage racks. This level is at elevation 816 ft. 6 in. for Units 1 and 2 and elevation 816 ft. 4 in. for Unit 3. In its letter dated July 19, 2013, the licensee provided a sketch showing the elevations identified as Levels 1, 2 and 3. The NRC staff reviewed this sketch and notes that Level 3 is identified at an elevation of 816 ft. 6 in. for the Units 1 and 2 SFP. The staff also notes that the Level 3 elevation for the Unit 3 SFP is not identified in the sketch. The staff has identified this request as: RAI #1 Please provide a sketch showing the approximate location of the SFP level instrumentation sensors and the elevations identified as Levels 1, 2 and 3 for the Unit 3 SFP. 3.3 Design Features:
Instruments Attachment 2 of Order EA-12-051, states, in part, that The instrumentation shall consist of a permanent, fixed primary instrument channel and a backup instrument channel. The backup instrument channel may be fixed or portable.
Portable instruments shall have capabilities that enhance the ability of trained personnel to monitor spent fuel pool water level under conditions that restrict direct personnel access to the pool, such as partial structural damage, high radiation levels, or heat and humidity from a boiling pool.
-7 NEI 12-02 states, in part, that A spent fuel pool level instrument channel is considered reliable when the instrument channel satisfies the design elements listed in Section 3 [Instrumentation Design Features]
of this guidance and the plant operator has fully implemented the programmatic features listed in Section 4 [Program Features].
In its OIP, the licensee stated that the instrumentation will consist of two diverse, permanent, fixed instrument channels to monitor SFP water level continuously.
The licensee also stated that indication of SFP level will be provided from approximately normal pool water level at elevation 841 ft., down to approximately the top of irradiated fuel assemblies seated in the storage racks at elevation 816 ft. 6 in., for Unit 1 and 2, and 816 ft. 4 in., for Unit 3. In its letter dated July 19, 2013, the licensee provided a sketch depicting that the SFP level instrumentation measurement range is 24 ft. 6 in. from the high pool level elevation to the top of the spent fuel racks. This sketch included a note stating that even though final location of equipment is not determined yet, the range would meet or exceed elevations defined by the maximum pool level and the top of the fuel racks. The NRC staff notes that the range specified for the licensee's instrumentation will cover Levels 1,2, and 3 as described in Section 3.2 above. The licensee's proposed plan, with respect to the number of channels and the range of the instrumentation for both of its SFPs, appears to be consistent with NEI 12-02, as endorsed by the ISG. 3.4 Design Features:
Arrangement Attachment 2 of Order EA-12-051, states, in part, that The spent fuel pool level instrument channels shall be arranged in a manner that provides reasonable protection of the level indication function against missiles that may result from damage to the structure over the spent fuel pool. This protection may be provided by locating the primary instrument channel and the fixed portions of the backup instrument channel, if applicable, to maintain instrument channel separation within the spent fuel pool area, and to utilize inherent shielding from missiles provided by existing recesses and corners in the spent fuel pool structure.
NEI 12-02 states, in part, that The intent of the arrangement requirement is to specify reasonable separation and missile protection requirements for permanently installed instrumentation used to meet this order. Although additional missile barriers are not required to be installed, separation and shielding can help minimize the probability that damage due to an explosion or extreme natural phenomena (e.g., falling or driven missiles) will render fixed channels of SFP instrumentation unavailable.
-8 Installation of the SFP instrument channels shall be consistent with the specific SFP design requirements and should not impair normal SFP function.
Channel separation should be maintained by locating the installed sensors in different places in the SFP area. In its OIP, the licensee stated, in part that The two SFP level instrument channels will be installed in diverse locations, arranged in a manner that provides reasonable protection of the level indication function against missiles that may result from damage to the structure over the SFP. The associated cabling, power supplies and indication for each level instrumenVchannel will be routed separately
'from each other. Cable routings will be specified to provide reasonable protection from missiles that may result from damage to the structure over the SFP and refuel floor, as applicable.
The conduit and cable routing will be determined by the detailed design. In its letter dated July 19, 2013, the licensee stated, in part, that The primary and backup channels will both utilize wave guided radar technology, which only requires a wave guided pipe and a receiving horn to be located in the SFP area. The wave guided pipe and receiving horn contain no organic materials and will not be susceptible to degradation due to exposure to radiation, heat, or steam. The electronics associated with all channels will be remotely located from the SFP inside the Seismic Category I Auxiliary Building.
Additionally, in its letter dated July 19, 2013, the licensee stated, in part, that Information is not available within the 28-day response period allotted for this RAI. Duke Energy anticipates submitting a response to RAI-2 for ONS in the February 2014 Six-Month Status Report for the Implementation of Order 051. The NRC staff notes that in its August 26, 2013 letter, the licensee stated that the detailed design work has not yet started. The staff also notes that the licensee anticipates submitting further information to the staff in the February 2014, six-month status report. The staff has identified these requests as: RAI #2 Please provide a clearly labeled sketch or marked-up plant drawing of the plan view of the SFP area, depicting the SFP inside dimensions, the planned locations/placement of the primary and back-up SFP level sensor, and the proposed routing of the cables that will extend from the sensors toward the location of the read-out/display device. (This information was previously requested as RAI-2 in the NRC letter dated June 21,2013)
-9 RAI Please provide additional information describing how the final arrangement of the SFP instrumentation and routing of the cabling between the level instruments, the electronics and the displays, meets the Order requirement to arrange the SFP level instrument channels in a manner that provides reasonable protection of the level indication function against missiles that may result from damage to the structure over the SFP. If applicable, please describe what precautions will be taken to ensure the back-up instrument's sensing line do not become susceptible to freezing during cold outside temperatures.
3.5 Design
Features:
Mounting Attachment 2 of Order EA-12-051 states, in part, that Installed instrument channel equipment within the spent fuel pool shall be mounted to retain its design configuration during and following the maximum seismic ground motion considered in the design of the spent fuel pool structure.
NEI 12-02 states, in part, that The mounting shall be designed to be consistent with the highest seismic or safety classification of the SFP. An evaluation of other hardware stored in the SFP shall be conducted to ensure it will not create adverse interaction with the fixed instrument location(s).
The basis for the seismic design for mountings in the SFP shall be the plant seismic design basis at the time of submittal of the Integrated Plan for implementing NRC Order EA-12-051.
In its OIP, the license stated that permanently installed instruments would be mounted to retain their design configuration during and following the maximum seismic ground motion considered in the design of the SFP structure or other building structure in which they are located. In its letter dated July 19, 2013, the licensee stated, in part, that The radar level instrument design will locate components in the SFP area such that they remain above the maximum water level in the SFP and the equipment mounts will not require any connections to be made to the pool liner. The mounting brackets for the wave guided assemblies and receiving horns will be secured to the SFP operating deck which is at EI844'-0".
The specific installation locations for the wave guided assemblies and receiving horns has not been finalized and this information is not available within the 28-day response period allotted for this RAI.
-In addition, in its letter dated July 19, 2013, the licensee stated, in part, that Information is not available within the 28-day response period allotted for this RAI. Duke Energy anticipates submitting a response to RAI-3 for ONS in the February 2014 Six-Month Status Report for the Implementation of Order 051. The NRC staff notes that in its August 26, 2013 letter, the licensee stated that the detailed design work has not yet started. The staff also notes that the licensee anticipates submitting further information to the staff in the February 2014, six-month status report. The staff has identified these requests as: RAI#4 Please provide the following:
a) The design criteria that will be used to estimate the total loading on the mounting device(s), including static weight loads and dynamic loads. Describe the methodology that will be used to estimate the total loading, inclusive of design basis maximum seismic loads and the hydrodynamic loads that could result from pool sloshing or other effects that could accompany such seismic forces. b) A description of the manner in which the level sensor (and stilling well, if appropriate) will be attached to the refueling floor and/or other support structures for each planned point of attachment of the probe assembly.
Indicate in a schematic the portions of the level sensor that will serve as points of attachment for mechanical/mounting or electrical connections.
c) A description of the manner by which the mechanical connections will attach the level instrument to permanent SFP structures so as to support the level sensor assembly. (This information was previously requested as RAI-3 in the NRC letter dated June 21,2013) In addition, the staff plans to verify the results of the licensee's seismic testing and analysis when it is completed based on the licensee's response to the following RAls. RAI#5 For RAI 4(a) above, please provide the analyses used to verify the design criteria and methodology for seismic testing of the SFP instrumentation and the electronics units, including, design basis maximum seismic loads and the hydrodynamic loads that could result from pool sloshing or other effects that could accompany such seismic forces.
-11 For each of the mounting attachments required to attach SFP Level equipment to plant structures, please describe the design inputs, and the methodology that was used to qualify the structural integrity of the affected structures/equipment.
S.6 Design Features:
Qualification Attachment 2 of Order EA-12-051 states, in part, that The primary and backup instrument channels shall be reliable at temperature, humidity, and radiation levels consistent with the spent fuel pool water at saturation conditions for an extended period. This reliability shall be established through use of an augmented quality assurance process (e.g. a process similar to that applied to the site fire protection program).
I\lEI 12-02 states, in part, that The instrument channel reliability shall be demonstrated via an appropriate combination of design, analyses, operating experience, and/or testing of channel components for the following sets of parameters, as described in the paragraphs below: conditions in the area of instrument channel component use for all instrument components, effects of shock and vibration on instrument channel components used during any applicable event for only installed components, and seismic effects on instrument channel components used during and following a potential seismic event for only installed components
... The NRC staff assessment of the instrument qualification is discussed in the following subsections below: (S.6.1) Augmented Quality Process and (S.6.2) Qualification and Reliability.
3.6.1 Augmented
Quality Process Appendix A-1 of the guidance in NE112-02 describes a quality assurance process for safety systems and equipment that is not already covered by existing quality assurance requirements.
Within the ISG, the NRC staff found the use of this quality assurance process to be an acceptable means of meeting the augmented quality requirements of Order EA-12-051.
In its OIP, the licensee stated that instrument reliability would be established through vendor qualification documents procured under an augmented quality assurance process defined by Duke Energy. The licensee's proposed augmented quality assurance process appears to be consistent with NEI 12-02, as endorsed by the ISG.
-12 3.6.2 Qualification and Reliability NEI 12-02 states, in part, that The temperature, humidity and radiation levels consistent with conditions in the vicinity of the [SFP] and the area of use considering normal operational, event and post-event conditions for no fewer than seven days post-event or until site resources can be deployed by the mitigating strategies resulting from Order EA-12-049 should be considered.
Examples of post-event basis) conditions to be considered are: radiological conditions for a normal refueling quantity of freshly discharged (100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br />) fuel with the SFP water level 3 as described in this order, temperatures of 212 degrees F and 100% relative boiling water and/or steam environment a concentrated borated water environment, and ... In its OIP, the licensee stated, in part, that All instrument channels will be specified to be reliable at the maximum temperature, humidity, and radiation levels predicted during an extended loss of AC power (ELAP) event at their installed locations.
The level instrumentation is to be designed to remain functional following a Safe Shutdown Earthquake.
In its letter dated July 19, 2013, the licensee stated, in part that Information is not available within the 28-day response period allotted for this RAI. Duke Energy anticipates submitting a response to RAI-4 for ONS in the February 2014 Six-Month Status Report for the Implementation of Order 051. The NRC staff notes that in its August 26, 2013 letter, the licensee stated that the detailed design work has not yet started. The staff also notes that the licensee anticipates submitting further information to the staff in the February 2014, six-month status report. The staff has identified these requests as: RAI#7 Please provide the following: A description of the specific method or combination of methods you intend to apply to demonstrate the reliability of the permanently installed equipment under BOB ambient temperature, humidity, shock, vibration, and radiation conditions. A description of the testing and/or analyses that will be conducted to provide assurance that the equipment will perform reliably under the worst-case credible design basis loading at the location where the equipment will be mounted. Include a discussion of this seismic reliability demonstration as it applies to a) the level sensor mounted in the SFP area, and b) any control boxes, electronics, or read-out and re-transmitting devices that will be employed to convey the level information from the level sensor to the plant operators or emergency responders. A description of the specific method or combination of methods that will be used to confirm the reliability of the permanently installed equipment such that following a seismic event the instrument will maintain its required accuracy. (This information was previously requested as RAI-4 in the NRC letter dated June 21,2013) In addition, the staff plans to verify the results of the licensee's testing and analysis used to demonstrate the qualification and reliability of the installed equipment when it is completed based on the licensee's response to the following RAI. RAI #8 For RAI #7 above, please provide the results for the selected methods, tests and analyses used to demonstrate the qualification and reliability of the installed equipment in accordance with the Order requirements.
3.6.3 Qualification
Evaluation Summary Upon acceptable resolution of the RAls in Section 3.6, the NRC staff will be able to make a conclusion regarding the instrument qualification.
3.7 Design
Features:
Independence Attachment 2 of Order EA-12-0S1 states, in part, that The primary instrument channel shall be independent of the backup instrument channel. NEI 12-02 states, in part, that Independence of permanently installed instrumentation, and primary and backup channels, is obtained by physical and power separation commensurate with the
-14 hazard and electrical isolation needs. If plant AC or DC power sources are used then the power sources shall be from different buses and preferably different divisions/channels depending on available sources of power. In its OIP, the licensee stated that the two level instruments and associated cabling for each SFP would be physically separated and electrically independent of one another. In its letter dated July 19, 2013, the licensee stated, in part, that Information is not available within the 28-day response period allotted for this RAI. Duke Energy anticipates submitting a response to RAI-S for ONS in the February 2014 Six-Month Status Report for the Implementation of Order OS1. The NRC staff notes that in its August 26,2013 letter, the licensee stated that the detailed design work has not yet started. The staff also notes that the licensee anticipates submitting further information to the staff in the February 2014, six-month status report. The staff has identified this request as: RAI #9 Please provide the following: A description of how the two channels of the proposed level measurement system meet this requirement so that the potential for a common cause event to adversely affect both channels is minimized to the extent practicable. Further information on how each level measurement system, consisting of level sensor electronics, cabling, and readout devices will be designed and installed to address independence through the application and selection of independent power sources, the use of physical and spatial separation, independence of signals sent to the location(s) of the readout devices, and the independence of the displays. (This information was previously requested as RAI-5 in the NRC letter dated June 21,2013) 3.8 Design Features:
Power Supplies Attachment 2 of Order EA-12-0S1, states in part, that Permanently installed instrumentation channels shall each be powered by a separate power supply. Permanently installed and portable instrumentation channels shall provide for power connections from sources independent of the plant ac and dc power distribution systems, such as portable generators or replaceable batteries.
Onsite generators used as an alternate power source and replaceable batteries used for instrument channel power shall have sufficient
-15 capacity to maintain the level indication function until offsite resource availability is reasonably assured. NEI 12-02 states, in part, that The normal electrical power supply for each channel shall be provided by different sources such that the loss of one of the channels primary power supply will not result in a loss of power supply function to both channels of SFP level instrumentation.
All channels of SFP level instrumentation shall provide the capability of connecting the channel to a source of power (e.g., portable generators or replaceable batteries) independent of the normal plant AC and DC power systems. For fixed channels this alternate capability shall include the ability to isolate the installed channel from its normal power supply or supplies.
The portable power sources for the portable and installed channels shall be stored at separate locations, consistent with the reasonable protection requirements associated with NEI 12-06 (Order EA-12-049).
The portable generator or replaceable batteries should be accessible and have sufficient capacity to support reliable instrument channel operation until off-site resources can be deployed by the mitigating strategies resulting from Order EA-12-049.
If adequate power supply for either an installed or portable level instrument credits intermittent operation, then the provisions shall be made for quickly and reliably taking the channel out of service and restoring it to service. For example, a switch on the power supply to the channel is adequate provided the power can be periodically interrupted without significantly affecting the accuracy and reliability of the instrument reading. Continuous indication of SFP level is acceptable only if the power for such indication is demonstrably adequate for the time duration specified in section 3.1 [.] In its OIP, the licensee stated, in part, that The two instrument channels for each SFP will be powered normally by separate power supplies backed up by rechargeable or replaceable batteries. The backup power sources will have sufficient capacity to maintain the level indication function until offsite power or other emergency resource availability is reasonably assured consistent with NEI 12-02 guidance.
In its letter dated July 19, 2013, the licensee stated, in part that Information is not available within the 28-day response period allotted for this RAI. Duke Energy anticipates submitting a response to RAI-6 for ONS in the February 2014 Six-Month Status Report for the Implementation of Order 051. The NRC staff notes that in its August 26,2013 letter, the licensee stated that the detailed design work has not yet started. The staff also notes that the licensee anticipates submitting
-further information to the staff in the February 2014, six-month status report. The staff has identified this request as: RAI #10 Please provide the following: A description of the electrical ac power sources and capabilities for the primary and backup channels. Please provide the results of the calculation depicting the battery backup duty cycle requirements demonstrating that its capacity is sufficient to maintain the level indication function until offsite resource availability is reasonably assured. (This information was previously requested as RAI-6 in the NRC letter dated June 21,2013. However, based on feedback from the licensees, this RAI has been revised as above.) 3.9 Design Features:
Accuracy Attachment 2 of Order EA-12-051 states, in part, that The instrument channels shall maintain their designed accuracy following a power interruption or change in power source without recalibration.
NEI 12-02 states, in part, that Accuracy should consider operations while under SFP conditions, e.g., saturated water, steam environment, or concentrated borated water. Additionally, instrument accuracy should be sufficient to allow trained personnel to determine when the actual level exceeds the specified lower level of each indicating range (levels 1, 2 and 3) without conflicting or ambiguous indication.
In its OIP, the licensee stated, in part, that The new SFP instrument channels will be capable of maintaining their designed accuracy without recalibration following a power interruption or change in power source. Accuracy will consider SFP post-event conditions, e.g., saturated water, steam environment, or concentrated borated water. Instrument accuracy will be sufficient to allow trained personnel to determine when the actual level exceeds the specified lower level of each indicating range (levels 1,2 and 3 as identified by NEI 12-02 guidance) without conflicting or ambiguous indication.
-In its letter dated July 19, 2013, the licensee stated, in part that Information is not available within the 28-day response period allotted for this RAI. Duke Energy anticipates submitting a response to RAI-7 for ONS in the February 2014 Six-Month Status Report for the Implementation of Order 051. The NRC staff notes that in its Al.lgust 26, 2013 letter, the licensee stated that the detailed design work has not yet started. The staff also notes that the licensee anticipates submitting further information to the staff in the February 2014, six-month status report. The staff has identified this request as: RAI #11 Please provide the following:
a) An estimate of the expected instrument channel accuracy performance under both (a) normal SFP level conditions (approximately Level 1 or higher) and (b) at the BOB conditions (i.e., radiation, temperature, humidity, post-seismic and post-shock conditions) that would be present if the SFP level were at the Level 2 and Level 3 datum points. b) A description of the methodology that will be used for determining the maximum allowed deviation from the instrument channel design accuracy that will be employed under normal operating conditions as an acceptance criterion for a calibration procedure to flag to operators and to technicians that the channel requires adjustment to within the normal condition design accuracy. (This information was previously requested as RAI-7 in the NRC letter dated June 21,2013) 3.10 Design Features:
Testing Attachment 2 of Order EA-12-051 states, in part, that The instrument channel design shall provide for routine testing and calibration.
NEI 12-02 states, in part, that Static or non-active installed (fixed) sensors can be used and should be deSigned such that testing and/or calibration can be performed in-situ. For microprocessor based channels the instrument channel deSign shall be capable of testing while mounted in the pool. In its OIP, the licensee stated that the instrument channel design shall provide for routine testing and calibration.
-18 In its letter dated July 19, 2013, the licensee stated, in part, that Information is not available within the 28-day response period allotted for this RAI. Duke Energy anticipates submitting a response to RAI-8 for ONS in the February 2014 Six-Month Status Report for the Implementation of Order 051. The NRC staff notes that in its August 26, 2013 letter, the licensee stated that the detailed design work has not yet started. The staff also notes that the licensee anticipates submitting further information to the staff in the February 2014, six-month status report. The staff has identified this request as: RAI #12 Please provide the following: A description of the capability and provisions the proposed level sensing equipment will have to enable periodic testing and calibration, including how this capability enables the equipment to be tested in-situ. b) A description of how such testing and calibration will enable the conduct of regular channel checks of each independent channel against the other, and against any other permanently-installed SFP level instrumentation.
c) A description of how functional checks will be performed, and the frequency at which they will be conducted.
Describe how calibration tests will be performed, and the frequency at which they will be conducted.
Provide a discussion as to how these surveillances will be incorporated into the plant surveillance program. d) A description of what preventive maintenance tasks are required to be performed during normal operation, and the planned maximum surveillance interval that is necessary to ensure that the channels are fully conditioned to accurately and reliably perform their functions when needed. (This information was previously requested as RAI-8 in the NRC letter dated June 21,2013) 3.11 Design Features:
Display Attachment 2 of Order EA-12-051 states, in part, that Trained personnel shall be able to monitor the spent fuel pool water level from the control room, alternate shutdown panel, or other appropriate and accessible
-location.
The display shall provide on-demand or continuous indication of spent fuel pool water level. NEI 12-02 states, in part, that The intent of this guidance is to ensure that information on SFP level is reasonably available to the plant staff and decision makers. Ideally there will be an indication from at least one channel of instrumentation in the control room. While it is generally recognized (as demonstrated by the events at Fukushima Daiichi) that SFP level will not change rapidly during a loss of spent fuel pool cooling scenario more rapid SFP drain down cannot be entirely discounted.
Therefore, the fact that plant personnel are able to determine the SFP level will satisfy this requirement, provided the personnel are available and trained in the use of the SFP level instrumentation (see Section 4.1) and that they can accomplish the task when required without unreasonable delay. SFP level indication from the installed channel shall be displayed in the control room, at the alternate shutdown panel, or another appropriate and accessible location (reference NEI12-06).
An appropriate and accessible location shall have the following characteristics: occupied or promptly accessible to the appropriate plant staff giving appropriate consideration to various drain down scenarios, outside of the area surrounding the SFP floor, e.g., an appropriate distance from the radiological sources resulting from an event impacting the SFP, inside a structure providing protection against adverse weather, and outside of any very high radiation areas or LOCKED HIGH RAD AREA during normal operation.
If multiple display locations beyond the required "appropriate and accessible location" are desired, then the instrument channel shall be designed with the capability to drive the multiple display locations without impacting the primary "appropriate and accessible" . In its OIP, the licensee stated that the instrument displays for each SFP level instrument would be provided in the main control room or other accessible location.
-In its letter dated July 19, the licensee provided an overview of the Instrument Channel Preliminary Design. In this section, the licensee stated, in part, that The primary channels will provide remote indication of SFP level in the associated Main Control Room (MCR). The backup channels will provide SFP level in locations remote from the SFP and the MCRs, but promptly accessible in the plant, as described in NEI 12-02. Additionally, in its letter dated July 19, 2013, the licensee stated, regarding the location of the channel displays, in part, that Information is not available within the 28-day response period allotted for this RAI. Duke Energy anticipates submitting a response to RAI-9 for ONS in the February 2014 Six-Month Status Report for the Implementation of Order 051. The NRC staff notes that in its July 19, 2013 letter, the licensee stated that the preliminary design would locate the primary channel display in the MCR and the backup channel display in a remote location, promptly accessible.
However, the staff also notes that in its August 26, 2013 letter, the licensee stated that detailed design work has not yet started. The staff also notes that the licensee anticipates submitting further information to the staff in the February 2014, six-month status report. The staff has identified this request as: RAI #13 Please provide the following:
a) The specific location for the primary and backup instrument channel display. b) For the SFP level instrumentation backup display located outside the MeR, please describe the evaluation used to validate that the display location can be accessed without unreasonable delay following a BOB event. Include the time available for personnel to access the display as credited in the evaluation, as well as the actual time (e.g., based on walk-throughs) that it will take for personnel to access the display. Additionally, please include a description of the radiological and environmental conditions on the paths personnel might take. Describe whether the display location remains habitable for radiological, heat and humidity, and other environmental conditions following a BOB event. Describe whether personnel are continuously stationed at the display or monitor the display periodically.
-21 3.12 Programmatic Controls:
Training Attachment 2 of Order EA-12-051 states, in part, that Personnel shall be trained in the use and the provision of alternate power to the primary and backup instrument channels.
NEI 12-02 states, in part, that The personnel performing functions associated with these SFP level instrumentation channels shall be trained to perform the job specific functions necessary for their assigned tasks (maintenance, calibration, surveillance, etc.). SFP instrumentation should be installed via the normal modification processes.
In some cases, utilities may choose to utilize portable instrumentation as a portion of their SFP instrumentation response.
In either case utilities should use the Systematic Approach to Training (SAT) to identify the population to be trained. The SAT process should also determine both the initial and continuing elements of the required training.
In its OIP, the licensee stated, in part, that Station personnel performing functions associated with the SFP level instrumentation will be trained to perform the job specific functions necessary for their assigned tasks. The Systematic Approach to Training (SAT) will be used to identify the population to be trained and to determine both the initial and continuing elements of the required training.
Training will be completed prior to placing the instrumentation in service. The licensee's proposed plan, with respect to the training personnel in the use and the provision of alternate power to the primary and backup instrument channels, including the approach to identifying the population to be trained, appears to be consistent with NEI 12-02, as endorsed by the ISG. 3.13 Programmatic Controls:
Procedures Attachment 2 of Order EA-12-051 states, in part, that Procedures shall be established and maintained for the testing, calibration, and use of the primary and backup spent fuel pool instrument channels.
NEI 12-02 states, in part, that Procedures will be developed using guidelines and vendor instructions to address the maintenance, operation and abnormal response issues associated with the new SFP instrumentation.
-In its OIP, the licensee stated that procedures will be developed using guidelines and vendor instructions to address the maintenance, operation and abnormal response issues associated with the SFP level instrumentation.
In its letter dated July 19, 2013, the licensee stated, in part that Information is not available within the 28-day response period allotted for this RAI. Duke Energy anticipates submitting a response to RAI-10 for ONS in the February 2014 Month Status Report for the Implementation of Order EA-12-051.
The NRC staff notes that in its August 26,2013 letter, the licensee stated that the detailed design work has not yet started. The staff also notes that the licensee anticipates submitting further information to the staff in the February 2014, six-month status report. The staff previously requested this information as RAI-10 in NRC letter dated June 21, 2013. However, based on feedback from licensees, the staff revised this HAl as follows: RAI #14 Please provide a list of the procedures addressing operation (both normal and abnormal response), calibration, test, maintenance, and inspection procedures that will be developed for use of the spent SFP instrumentation.
The licensee is requested to include a brief description of the specific technical objectives to be achieved within each procedure.
3.14 Programmatic Controls:
Testing and Calibration Attachment 2 of Order EA-12-051 states, in part, that Processes shall be established and maintained for scheduling and implementing necessary testing and calibration of the primary and backup spent fuel pool level instrument channels to maintain the instrument channels at the design accuracy.
NEI 12-02 states, in part, that Processes shall be established and maintained for scheduling and implementing necessary testing and calibration of the primary and backup SFP level instrument channels to maintain the instrument channels at the design accuracy.
The testing and calibration of the instrumentation shall be consistent with vendor recommendations or other documented basis. In its OIP, the licensee stated that Testing and calibration of the instrumentation will be consistent with vendor recommendations or other documented basis, and that calibration will be specific to the mounted instrument(s) and the display(s).
In its letter dated July 19,2013, the licensee stated, in part, that Information is not available within the 28-day response period allotted for this RAI. Duke Energy anticipates submitting a response to RAI-11 for ONS in the
-February 2014 Six-Month Status Report for the Implementation of Order 051. The NRC staff notes that in its August 26, 2013 letter, the licensee stated that the detailed design work has not yet started. The staff also notes that the licensee anticipates submitting further information to the staff in the February 2014, six-month status report. The staff has identified this request as: RAI #15 Please provide the following: Further information describing the maintenance and testing program the licensee will establish and implement to ensure that regular testing and calibration is performed and verified by inspection and audit to demonstrate conformance with design and system readiness requirements.
Please include a description of the plans for ensuring that necessary channel checks, functional tests, periodic calibration, and maintenance will be conducted for the level measurement system and its supporting equipment.
b) Information describing compensatory actions when both channels are out-of-order, and the implementation procedures.
c) Additional information describing expedited and compensatory actions in the maintenance procedure to address when one of the instrument channels cannot be restored to functional status within 90 days. (This information was previously requested as RAI-11 in the NRC letter dated June 21,2013. However, based on feedback from the licensees, this RAI has been revised as above.) 3.15 Instrument Reliability NEI 12-02 states, in part, that A spent fuel pool level instrument channel is considered reliable when the instrument channel satisfies the design elements listed in Section 3 [Instrument Design Features]
of this guidance and the plant operator has fully implemented the programmatic features listed in Section 4 [Program Features].
In its OIP, the licensee stated that reliability of the instrument channels would be assured by conformance with the guidelines of NRC JLD-ISG-2012-03 and NEI 12-02.
-Upon acceptable resolution of the RAls noted above, the NRC staff will be able to make a conclusion regarding the reliability of the SFP instrumentation.
4.0 CONCLUSION
The NRC staff is unable to complete its evaluation regarding the acceptability of the licensee's plans for implementing the requirements of Order EA-12-051 due to the need for additional information as described above. The staff will issue an evaluation with its conclusion after the licensee has provided the requested information.
S. Batson -2 must complete full implementation of Order EA-12-051.
The licensee should adjust its schedule for providing information to ensure that all this information is provided by the requested date. A final NRC staff evaluation will be issued after the licensee has provided the information requested.
If you have any questions regarding this letter, please contact me at 301-415-1030 or via e-mail at Richard. Guzman@nrc.gov.
Sincerely, IRA! Richard V. Guzman, Senior Project Manager Plant Licensing Branch 11-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-269, 50-270, and 50-287
Enclosure:
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