RS-11-177, Units 1 & 2 - Additional Information Supporting License Amendment Request to Revise Technical Specifications (TS) 3.3.1, Reactor Trip System (RTS) Instrumentation, and TS 3.3.2, Engineered Safety Feature Actuation.
| ML113220181 | |
| Person / Time | |
|---|---|
| Site: | Byron, Braidwood  |
| Issue date: | 11/18/2011 |
| From: | Gullott D Exelon Generation Co, Exelon Nuclear |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| RS-11-177 | |
| Download: ML113220181 (8) | |
Text
Exelon Generation www.exeloncorp.com 4300 Winfield Road Nu c le ar Warrenville, IL 60555 RS-11-177 10 CFR 50.90 November 18, 2011 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-001 Braidwood Station, Units 1 and 2 Facility Operating License Nos. NPF-72 and NPF-77 NRC Docket Nos. STN 50-456 and STN 50-457 Byron Station, Units 1 and 2 Facility Operating License Nos. NPF-37 and NPF-66 NRC Docket Nos. STN 50-454 and STN 50-455
Subject:
Additional Information Supporting License Amendment Request to Revise Technical Specifications (TS) 3.3.1, "Reactor Trip System (RTS) Instrumentation,"
and TS 3.3.2, "Engineered Safety Feature Actuation System (ESFAS)
Instrumentation," to Reflect Installation of Bypass Test Capability
References:
- 1. Letter from J. L. Hansen (Exelon Generation Company, LLC) to U. S. Nuclear Regulatory Commission, "License Amendment Request To Revise Technical Specifications (TS) 3.3.1, 'Reactor Trip System (RTS) Instrumentation,' and TS 3.3.2, 'Engineered Safety Feature Actuation System (ESFAS)
Instrumentation,' To Reflect Installation of Bypass Test Capability," dated March 14, 2011
- 2. Letter from D. M. Gullott (Exelon Generation Company, LLC) to U. S. Nuclear Regulatory Commission, "Response to Request for Additional Information Related to License Amendment Request to Revise Technical Specifications (TS) 3.3.1, 'Reactor Trip System (RTS) Instrumentation,' and TS 3.3.2,
'Engineered Safety Feature Actuation System (ESFAS) Instrumentation,' to Reflect Installation of Bypass Test Capability," dated September 2, 2011
- 3. Letter from N. J. DiFrancesco (U. S. Nuclear Regulatory Commission) to M. J. Pacilio (Exelon Generation Company, LLC), "Braidwood Station, Units 1 and 2, Byron Stations, Unit Nos. 1 and 2 - Request for Additional Information Regarding License Amendment Request to Revise Technical Specifications with Bypass Test Capability (TAC Nos. ME5836, ME5837, ME5838, and ME5839)," dated November 8, 2011
November 18, 2011 U. S. Nuclear Regulatory Commission Page 2 In Reference 1, Exelon Generation Company, LLC, (EGC) requested a license amendment to revise Technical Specifications (TS) 3.3.1, "Reactor Trip System (RTS) Instrumentation," and TS 3.3.2, "Engineered Safety Feature Actuation System (ESFAS) Instrumentation," for Braidwood Station, Units 1 and 2, and Byron Station, Units 1 and 2, to reflect the planned installation of the bypass test capability. EGC supplemented Reference 1 by letter dated September 2, 2011 (Reference 2).
In Reference 3, the NRC requested additional information to complete the review of the proposed license amendment. In response to this request, EGC is providing the attached information. The Attachment provides the requested responses.
EGC has reviewed the information supporting a finding of no significant hazards consideration and the environmental consideration that were previously provided to the NRC in Attachment 1 of Reference 1. The additional information provided in this submittal does not affect the bases for concluding that the proposed license amendment does not involve a significant hazards consideration. In addition, the additional information provided in this submittal does not affect the bases for concluding that neither an environmental impact statement nor an environmental assessment needs to be prepared in connection with the proposed amendment.
In accordance with 10 CFR 50.91, "Notice for public comment; State consultation," paragraph (b),
a copy of this letter and its attachment are being provided to the designated State of Illinois official.
There are no regulatory commitments contained in this submittal. Should you have any questions concerning this letter, please contact Ms. Lisa A. Simpson at (630) 657-2815.
I declare under penalty of perjury that the foregoing is true and correct. Executed on the 18th day of November 2011.
Respectfully, David M. Gullott Manager - Licensing Exelon Generation Company, LLC
Attachment:
Response to Request for Additional Information cc: NRC Regional Administrator, Region III NRC Senior Resident Inspector, Braidwood Station NRC Senior Resident Inspector, Byron Station NRR Project Manager - Braidwood and Byron Stations Illinois Emergency Management Agency - Division of Nuclear Safety
ATTACHMENT Response to Request for Additional Information By letter to the Nuclear Regulatory Commission (NRC) dated March 14, 2011, Exelon Generation Company, LLC, (EGC) requested a license amendment to revise Technical Specifications 3.3.1, "Reactor Trip System (RTS) Instrumentation," and Technical Specifications 3.3.2, "Engineered Safety Feature Actuation System (ESFAS) Instrumentation," for Braidwood Station, Units 1 and 2, and Byron Station, Units 1 and 2, to reflect the planned installation of the bypass test capability.
EGC supplemented this license amendment request by letter dated September 2, 2011.
In a letter dated November 8, 2011, the NRC requested that EGC provide additional information in support of its review of the March 14, 2011, request.
NRC Question 1:
Please discuss the interfaces between the Bypass Test Instrumentation (BTI) and the main control room (MCR) indications which enable the operators to recognize which loops are in bypass at any one time so as to avoid potential technical specification violations regarding minimum channel requirements. Each type of BTI (i.e., 7300 card) and nuclear instrumentation system (NIS) provides a description of the following:
- a. Describe local light emitting diode indications, MCR alarms, and safety evaluation report indications that occur when a channel is placed into "Test" or "Bypass Enable" and when a loop is placed into "Bypass."
- b. Describe any additional controls in place, beyond those provided in WCAP-17349-P, Section 3.5, which prevent inadvertent placement of two loops in different channels from being placed into bypass simultaneously.
Response to Question 1.a:
7300 CARD BTI (Assuming Group 2 card for up to four comparators. Note: Group 1 cards are similar but only provide circuits for two comparators):
This discussion assumes a Group 2 NBC or NBT card, which can bypass up to four comparators for a single loop. No single card bypasses comparators for more than one loop. There are four Bypass Permissive Lights, one associated with each cabinet (division).
When a 7300 loop is in a "Normal" configuration, the associated NBC or NBT card for that loop has the BPT-1/2/3/4 light emitting diodes (LEDs) lit, indicating that there are no comparators bypassed for the affected loop. The CHAN IN TEST and OUT 1/2/3/4 LEDs are dark. There are no MCR alarms for the associated loop, and the sequence of event recorder (SER) indicates NOT BYPASSED for the affected loop.
When the loop is placed to "Test" without being in "Bypass" (i.e., typically in a tripped condition),
the CHAN IN TEST LED illuminates on the associated NBC or NBT card. The BPT-1/2/3/4 LEDs stay lit, since no comparators are bypassed. The OUT 1/2/3/4 LEDs will illuminate depending on the state of their associated comparator. The MCR will receive alarms associated with the loop being placed into test, which would be Trip Status Lights (TSLBs) and alarms associated with the loop comparators being in the tripped condition. The SER will indicate the same tripped status for the loop comparators and will still indicate NOT BYPASSED for the affected loop.
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ATTACHMENT Response to Request for Additional Information When the loop comparators are placed to "Bypass" with the loop already in "Test," the BPT-1/2/3/4 LEDs will go dark for each comparator as it is bypassed. The OUT 1/2/3/4 LEDs will still illuminate depending on the state of their associated comparator as described previously. The comparators are bypassed downstream of the OUT 1/2/3/4 LEDs, so these LEDs are not dependent on the "Bypass" status, only on "Test" status for the loop. The first comparator to be bypassed will cause annunciator 03E04 for the applicable unit to illuminate at 1/2PM06J with an associated audible alarm, a Bypass Permissive Light-1.9/2.9/3.9/4.9 (dependent on cabinet) will illuminate at 1/2PM05J with an associated audible alarm, and the SER will now indicate BYPASSED for the affected loop. It does not matter what order the comparators are bypassed in, any comparator in bypass will cause the indications described in the previous sentence. As each comparator is bypassed, the TSLBs, annunciators, and SER points associated with that comparator being in a tripped condition will reset. After all comparators for the loop are bypassed, the only SER indication for the loop will be that it is BYPASSED, while the 1/2PM06J annunciator 03E04 and 1/2PM05J Bypass Permissive Light-1.9/2.9/3.9/4.9 will remain lit.
The other possible loop configuration is placing the loop directly into "Bypass" without going into "Test." This paragraph assumes we are starting from the "Normal" configuration as described above. As each comparator is bypassed, its associated BPT-1/2/3/4 LED will go dark. When the first comparator is placed to "Bypass," annunciator 03E04 will illuminate at 1/2PM06J with an associated audible alarm, a Bypass Permissive Light-1.9/2.9/3.9/4.9 will illuminate at 1/2PM05J with an associated audible alarm, and the SER will now indicate BYPASSED for the affected loop.
The CHAN IN TEST LED is dark, as the channel is not in test. The OUT 1 /2/3/4 LEDs are dark, as they are only in the circuit when the loop is in "Test."
NIS Bypass Test Panel:
For the NIS Bypass Test Panels, the two Bypass switches on the right are not utilized at Braidwood and Byron. They will be left in the NORMAL position.
When an NIS channel is in a "Normal" configuration, there are no LEDs illuminated on the Bypass panel, and the panel is deenergized via the "Safety" and "Non-Safety" circuit breakers located on the upper left and upper right of the Bypass Panel. These circuit breakers are normally OFF. All eight Bypass switches are in the NORMAL (down) position, and the BYPASS ENABLE keyswitch is in the NORMAL (vertical) position. The SER will indicate a NOT BYPASSED status for the channel. There will be no MCR alarms for the channel if it is in a "Normal" configuration.
To place an NIS channel to Bypass enable, the "Safety" and "Non-Safety" circuit breakers on the Bypass panel are first turned on and will illuminate indicating power available. No LEDs should illuminate at this time, since all the panel switches are still in their normal alignment. The BYPASS ENABLE keyswitch is then taken to the BYPASS ENABLE position. This will cause the BYPASS ENABLE LED to illuminate. It will also cause annunciator 03E04 to illuminate at 1/2PM06J with an associated audible alarm, a Bypass Permissive Light-1.9/2.9/3.9/4.9 will illuminate at 1/2PM05J with an associated audible alarm, and the SER will now indicate BYPASSED for the affected channel.
When each NIS function bypass switch is placed to BYPASS, its associated LED (e.g., P10 PERMISS.) will illuminate. These bypass switches only have an effect when the BYPASS ENABLE keyswitch is in the BYPASS ENABLE position. There is no additional annunciation or Page 2 of 6
ATTACHMENT Response to Request for Additional Information SER indication for the individual functions going into bypass, assuming the sequence started from a normal condition. If starting from a failed loop, as each function is bypassed, the TSLBs, annunciators and SER points associated with any comparator that was in a tripped condition will reset to their non-tripped status.
For the P-8 and P-10 permissives and for the Low Setpoint Neutron Flux Trip, the non-tripped status corresponds to being below their respective setpoint. After all comparators for the loop are bypassed, the SER indications for the loop will be that it is BYPASSED and the loop will indicate below P-8, P-10, and the Low Setpoint Neutron Flux Trip on the SER. The 1/2PM06J annunciator 03E04 and 1/2PM05J Bypass Permissive Light-1.9/2.9/3.9/4.9 will remain lit.
Response to Question 1.b:
Additional controls beyond those provided in WCAP-1 7349- P Section 3.5 are also administrative in nature. They are associated with the Instrument Maintenance and Operations procedures associated with 7300 and NIS surveillance and Maintenance activities. Details are as follows:
Instrument Maintenance (IMD):
A typical IMD procedure implements the following administrative controls:
- 1) A peer check for proper work location is performed as a Prerequisite to performing work.
- 2) A verification that no coincident channels are tripped is performed prior to going to Test or Bypass.
- 3) A verification of the Bypass Permissive Lights is performed to verify no channels are in Bypass prior to going to Test or Bypass. (This requirement is being added based on BTI modification.)
- 4) Verification is utilized for all steps when going into and out of Test or Bypass.
Operations:
The Operations administrative controls are as follows:
- 1) There are MCR Trip Status Lights (TSLBs) on the 1/2PM05J panel to indicate which 7300 protection cabinet door is being opened. This is a backup to the key lock system to ensure that the proper cabinet door is being accessed.
- 2) There is a MCR 1/2PM06J annunciator 04E01 and audible alarm which actuates when two or more 7300 protection cabinets have a door open at the same time. The annunciator response for this alarm is to verify proper authorization for cabinet entry and stop cabinet entry if not authorized. This alarm occurs when the cabinet doors are opened, prior to any physical manipulations in the cabinet. This is also a backup to the key lock system.
- 3) The NIS cabinets also have external key locks which are specific keys for each channel.
These locks are required to be opened to access the NIS bypass panels. These keys are kept in the MCR under Operations control.
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ATTACHMENT Response to Request for Additional Information NRC Question 2:
Technical specification Table 3.3.1-1, indicates the number of required channels is four for each of the following reactor trip systems (RTS) functions:
FUNCTION:
- 2. Power Range Neutron Flux
- a. High
- b. Low
- 3. Power Range Neutron Flux - High Positive Rate However, page 5 of the licensee amendment request (LAR), dated March 14, 2011, indicate the NIS functions use 1-out-of-2 logic stated below:
"In general, the RTS and ESFAS utilize two-out-of-three and two-out-of-four coincidence logic from redundant channels to initiate protective actions. Within these systems, analog channel comparators, with the exceptions of the NIS one-out-of-two functions and the ESFAS containment spray function, are currently placed in the tripped state for channel testing or in response to a channel being out of service."
Please explain the statement of "NIS one- out-of-two functions," while the TS required channels is four, and list the NIS functions which use one-out-of-two logic.
Response to Question 2: of EGC License Amendment Request dated March 14, 2011, includes the following paragraph:
In general, the RTS and ESFAS utilize two-out-of-three and two-out-of-four coincidence logic from redundant channels to initiate protective actions. With these systems, analog channel comparators, with the exceptions of the NIS one-out-of-two functions and the ESFAS containment spray function, are currently placed in the tripped state for channel testing or in response to a channel being out of service. With a channel in the tripped condition, a second comparator trip in a redundant channel caused by human error, a spurious transient, or channel failure would initiate a reactor trip or safeguards actuation.
The intent of the paragraph was to provide a general statement of the typical configuration of the comparator outputs during channel testing. Although the RTS and ESFAS functions are typically two-out-of-three and two-out-of-four coincidence logic, this paragraph acknowledges that not all of the functions use this logic.
The exceptions of the'NIS one-out-of-two' functions are referring to the NIS Intermediate Range Neutron Flux and the Source Range Neutron Flux trip functions listed as functions 4 and 5 respectively in Technical Specifications Table 3.3.1-1, "Reactor Trip System Instrumentation." As listed in this table, the Technical Specifications required channels for these functions is shown as two for both functions. This is because there are only two protection related source range detectors and two protection related Intermediate range detectors.
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ATTACHMENT Response to Request for Additional Information The trip logic related to these channels is one-out-of-two for each function while the unit is operating in the applicable mode. A trip signal generated from either channel will result in a reactor trip. When the unit is operating above the applicable mode for the respective function, these functions are blocked so that no reactor trip will occur. Based on these channels being blocked at power and these drawers originally furnished with built-in trip bypass capability, additional bypass circuitry is not being added to these channels through the bypass test modification; therefore, these channel functions were not included in the licensee amendment request.
NRC Question 3:
Drawings 6065D99, sheets 4 and 5, show that the signals of following functions are wired to the BTI panel:
- Power above permissive P-10
- Overpower rod stop
- Power above permissive P-9
- Overpower trip low range
- Overpower trip high range
- Positive rate trip
- Power above permissive P-8 But the LAR only mentioned the following three:
Overpower trip low range
- Overpower trip high range Positive rate trip Describe how this BTI installation affects all the other functions, and provide regulatory compliance for those functions.
Response to Question 3:
As stated in NRC Question 3, the EGC License Amendment Request dated March 14, 2011, mentioned, in part, the following functions:
Power Range Neutron Flux - Low Range (i.e., Overpower trip low range)
Power Range Neutron Flux - High Range (i.e., Overpower trip high range)
Power Range Neutron Flux - High Positive Rate (i.e., Positive rate trip)
In addition to allowing the three listed RTS instrumentation functions to be tested in bypass following implementation of the bypass test instrumentation modification, the change proposed in the EGC License Amendment Request dated March 14, 2011, would revise, in part, certain Required Actions Notes in TS 3.3.1, Conditions D and E, to reflect installed bypass capability.
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ATTACHMENT Response to Request for Additional Information The following describes how this BTI installation aff ects the remaining four functions:
Power above permissive P-10 The Power above permissive P-10 function is a Technical Specifications function as identified in Technical Specifications Table 3.3.1-1 (i.e., Power Range Neutron Flux, P-10); however, this function is not associated with the proposed changes to the Technical Specifications in EGC License Amendment Request dated March 14, 2011. The Technical Specifications contain no Required Action for the Power above permissive P-10 function and as such do not have Notes similar to the functions mentioned in the License Amendment Request that are proposed to be changed. Therefore, no Technical Specifications changes are needed for the Power above permissive P-10 function. Changes necessary to be made to the Power above permissive P-10 function as part of the bypass test capability modification will be implemented in accordance with 10 CFR 50.59. The BTI installation allows placing and maintaining the P-10 permissive in the RESET (non-tripped) condition during testing/calibration.
Power above permissive P-8 The Power above permissive P-8 function is a Technical Specifications function as identified in Technical Specifications Table 3.3.1-1 (i.e., Power Range Neutron Flux, P-8); however, this function is not associated with the proposed changes to the Technical Specifications in EGC License Amendment Request dated March 14, 2011. The Technical Specifications contain no Required Action for the Power above permissive P-8 function and as such do not have Notes similar to the functions mentioned in the License Amendment Request that are proposed to be changed. Therefore, no Technical Specifications changes are needed for the Power above permissive P-8 function. Changes necessary to be made to the Power above permissive P-8 function as part of the bypass test capability modification will be implemented in accordance with 10 CFR 50.59. The BTI installation allows placing and maintaining the P-8 permissive in the RESET (non-tripped) condition during testing/calibration.
Overpower rod stop The Power Range - Overpower Rod Stop function is not a Technical Specifications function and is not associated with the proposed changes to the Technical Specifications in EGC License Amendment Request dated March 14, 2011. No specific Technical Specifications Required Action is required for the Overpower rod stop function. Changes necessary to be made to the Overpower rod stop function will be implemented in accordance with 10 CFR 50.59. The BTI installation allows maintaining the Power Range - Overpower Rod Stop function in the RESET (non-tripped) condition during testing/calibration.
Power above permissive P-9 Braidwood and Byron do not utilize the Power above permissive P-9 function. The function is identified as "P-9 Spare" in WCAP-17349-P, Table 2. In addition, this is a spare function as identified by the dashed line on Westinghouse drawing 6065D99 sheet 5.
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