ML15216A365
| ML15216A365 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 07/30/2015 |
| From: | Mark D. Sartain Dominion, Dominion Nuclear Connecticut |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| 15-288A, GL-08-001, TAC MF5715, TAC MF5716 | |
| Download: ML15216A365 (21) | |
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Do~uminion Dominion Nuclear Connecticut, Inc.
5000 Dominion Boulevard, Glen Allen, VA 23060 Web Address: www.dom.com U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555-0001 July 30, 2015 Serial No.
N LOS/VDC Docket Nos.
License Nos.
1 5-288A R1 50-336/423 DPR-65 N PF-49 DOMINION NUCLEAR CONNECTICUT. INC.
MILLSTONE POWER STATION UNITS 2 AND 3 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION REGARDING LICENSE AMENDMENT REQUEST TO ADOPT TSTF-523. REVISION 2. GENERIC LETTER 2008-01. MANAGING GAs ACCUMULATION (TAC NO. MF5715 & MF5716)
By letter dated January 15, 2015, and supplemented by letter dated April 15, 2015, Dominion Nuclear Connecticut, Inc. (DNC) submitted a license amendment request (LAR) for Millstone Power Station Unit 2 (MPS2) and Millstone Power Station Unit 3 (MPS3). The proposed amendment would modify technical specification requirements to address Generic Letter 2008-01, "Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems," as described in Technical Specifications Task Force (TSTF)-523, Revision 2, "Generic Letter 2008-01, Managing Gas Accumulation."
TSTF-523, Revision 2 is approved for use by the Nuclear Regulatory Commission (NRC) and was announced in the Federal Register on January 15, 2014 (79 FR 2700). In an email dated June 1, 2015, the NRC transmitted a request for additional information (RAI) containing nine questions related to the LAR. In a letter dated July 17, 2015, DNC responded to RAI Questions 2, 3, 4, 5, and 6.
The attachment to this letter provides DNC's response to the remaining four questions of the NRC's RAI - Questions 1,7, 8, and 9.
If you should have any questions regarding this submittal, please contact Wanda Craft at (804) 273-4687.
Sincerely, Mark D. Sartain Vice President - Nuclear Engineering COMMONWEALTH OF VIRGINIA COUNTY OF HENRICO
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The foregoing document was acknowledged before me, in and for the County aforesaid, today by Mr. Mark D. Sartain, who is Vice President - Nuclear Engineering, of Dominion Nuclear Connecticut.
He has affirmed before me that he is duly authorized to execute and file the foregoing document in behalf of that company, and that the statements in the document are true to the best of his knowledge and belief.
Acknowledged before me this,.*1 day of JAlll
,2015.
CRAIG* D SLY.
My Commission Expires: )*i3I I f(*
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- My Commission Expires D.ecember 31, 20L.'
Serial No.15-288 Docket Nos. 50-336/423 Page 2 of 2
Attachment:
Response to Request for Additional Information Regarding License Amendment Request to Adopt TSTF-523 - Questions 1, 7, 8, and 9 Commitments contained in this letter: None cc:
U.S. Nuclear Regulatory Commission Region I 2100 Renaissance Blvd Suite 100 King of Prussia, PA 19406-2713 Richard V. Guzman NRC Senior Project Manager U.S. Nuclear Regulatory Commission One White Flint North, Mail Stop 08 C2 11555 Rockville Pike Rockville, MD 20852-2738 NRC Senior Resident Inspector Millstone Power Station Director, Radiation Division Department of Energy and Environmental Protection 79 Elm Street Hartford, CT 06106-5127
Serial No. 1 5-288A Docket Nos. 50-336/423 ATTACHMENT RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION REGARDING LICENSE AMENDMENT REQUEST TO ADOPT TSTF-523 -
QUESTIONS 1, 7, 8, AND 9 DOMINION NUCLEAR CONNECTICUT, INC.
MILLSTONE POWER STATION UNITS 2 AND 3
Serial No. 15-288A Docket Nos. 50-336/423 Attachment, Page 1 of 18 By letter dated January 15, 2015, and supplemented by letter dated April 15, 2015, Dominion Nuclear Connecticut, Inc. (DNC) submitted a license amendment request (LAR) for Millstone Power Station Unit 2 (MPS2) and Millstone Power Station Unit 3 (MPS3).
The proposed amendment would modify Technical Specification (TS) requirements to address Generic Letter 2008-01, "Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems," as described in Technical Specifications Task Force (TSTF)-523, Revision 2, "Generic Letter 2008-01, Managing Gas Accumulation." TSTF-523, Revision 2 is approved for use by the Nuclear Regulatory Commission (NRC) and was announced in the Federal Register on January 15, 2014 (79 FR 2700). In an email dated June 1, 2015, the NRC transmitted a request for additional information (RAI) related to the LAR.
In a letter dated July 17, 2015, DNC responded to Questions 2, 3, 4, 5, and 6 of the RAI. This attachment provides DNC's response to the remainder of the NRC's RAI questions -
Questions 1, 7, 8, and 9.
RAIl1 Please clarify use of the Froude number, as follows:
- a. The License Amendment Request (LAR) referenced Generic Letter (GL) 2008-
- 01. The response to GL 2008-01 states that a Froude number > 0. 70 will remove gas from piping. This is inconsistent with the NEI 09-10, "Guidelines for Effective Prevention and Management of System Gas Accumulation," and the NRC's safety evaluation that approved NEI 09-10.
Please explain this apparent inconsistency.
- b. In the GL response, some locations are stated to be ensured to be gas free by use of a sufficient flow rate. What are the Froude numbers used at these locations? If a system is not exempted because it is in operation, how long is flow maintained when gas removal is being accomplished?
DNC Response
- a. At the time of the GL 2008-01 responses, MPS2 and MPS3 performed its evaluation of a flow rate's ability to sweep, flush, or remove voids from piping based on a Froude number > 0.7. This value was obtained from a 1998 vendor (Creare Inc.) test report that was used to support MPS3's gas monitoring program up to year 2008, which was prior to issuance of NEI 09-10, Revision 0.
In October 2009, NEI 09-10, Rev. 0 was issued recommending that dynamic venting flow rates be based on a single Froude number of_> 1.0. By April 2013, the latest (NRC approved) NEI 09-10, Rev. Ia guidance recommended a dynamic venting Froude range of 0.8 < NFR < 2.0 depending on pipe geometry and available flush time.
Because flush time was not well characterized, a Froude number > 2.0 was preferred. For the locations where dynamic venting is credited at MPS2 and MPS3, each location has a Froude number > 0.8. Most
Serial No. 15-288A Docket Nos. 50-336/423 Attachment, Page 2 of 18 locations have a Froude number > 1.0 and some meet the preferred Froude number of > 2.0. Operating experience at MPS2 and MPS3 has demonstrated that dynamic venting at these locations has been successful at these Froude numbers (which are based on flow rates specified in procedures and their inherent run times).
- b. For MPS2, a list of the locations that would be ensured to be gas free due to sufficient flow rate is provided in the table below. For each location, details of the corresponding flow rate, Froude number, and length of time flow is maintained during gas removal (flush time) are also provided.
Location Flow Rate (gpm)
[Pipe SizelFroude No. ] Flush Time High Pressure Safety Injection (HPSI) pump discharge header from the pumps to the tie to the individual Low Pressure Safety Injection (LPSI) pump injection lines The flow rate during plant refueling outages when a HPSI pump is used to fill the reactor cavity can be either 300 gpm (75 gpm per cold leg) or 600 gpm (150 gpm per cold leg) depending on procedure.
In addition, a comprehensive (high) flow pump in-service test (IST) is performed at 500 gpm for each HPSI pump during plant refueling outages.
Common Lines 3" sch. 80 /
5.24 @ 300 gpm 10.47 @ 600 gpm 4" sch. 80 I 2.62 @ 300 gpm 5.24 @ 600 gpm 6" sch. 80 /
0.94* @ 300 gpm 1.88 @ 600 gpm
- A Froude number slightly < 1.0 is acceptable here because the piping run is either horizontal or vertically upward.
Per the NEI guidance, a Froude Number >
0.54 is required to move a gas void toward the downstream end of a horizontal pipe.
Individual Loop Lines 2" sch. 160 I 5.07 @ 75 gpm 10.14 @ 150 gpm 3" sch. 160 /
1.68 @ 75 gpm 3.36 @ 150 gpm These activities are normal plant functions performed during refueling outages.
A flush time is not specified in the procedures. The run time of a HPSI pump while performing any of these activities is typically > 10 minutes, which is considered sufficient to flush the system piping.
Serial No. 15-288A Docket Nos. 50-336/423 Attachment, Page 3 of 18 Location Flow Rate (gpm)
Pipe SizelFroude No.
Flush Time LPSI pump The flow rate during plant Common Lines A flush time is not discharge header shutdowns when 10" sch. 20 /
specified in the from the pumps to shutdown cooling (SDC) 2.60 @ 3500 gpm procedure the reactor coolant is in service is a minimum because water is system (RCS) of 3500 gpm (875 gpm 12" sch. 20 /
flowing per cold leg). Flow is into 1.67 @ 3500 gpm continuously while the RCS.
SDC is in service.
Individual Loop Lines Both trains of LPSI 6" sch. 10S /
are flushed prior to 2.15 @875 gpm the end of a refueling outage.
6" sch. 160 /
3.57 @ 875 gpm 6" sch. 120 /
__________________3.08
@ 875 gpm Boron precipitation 41 gpm single charging 2" sch. 160 /
The flush time is (alternate hot leg pump flow rate during 2.8 @ 41 gpm continuous via a injection method) normal plant operation charging pump into RCS hot legs continually sweeps the 2" during normal via HPSI pump (P-discharge piping. The plant operation.
41A) through the flowrate during boron charging system into precipitation with a HPSI the pressurizer pump would be higher.
auxiliary spray line Containment spray In addition to the 10" sch. 20 /
>8 minutes (CS) pump suction minimum flow 1.02 @ 1377 gpm line recirculation line, this pump can be aligned to the full flow recirculation test line during normal plant operations which allows for dynamic venting at 1377-1412 gpm following on-line
_______________ maintenance.
Serial No. 15-288A Docket Nos. 50-336/423 Attachment, Page 4 of 18 Location Flow Rate (gpm)
Pipe SizelFroude No.
>__20.4 gpm from HPSI 2" sch. 80 /
A flush time is not pump minimum flow pump performed 0.97* @ 20.4 gpm specified in the recirculation lines to quarterly, procedures.
The the refueling water 2" sch. 40 and sch.
run time per pump storage tank
>__28.8 gpm from CS 80/
necessary to (RWST) pump performed 1.17 @ 28.8 gpm obtain IST data is quarterly, 4.48 @ 110 gpm typically > 10 minutes, which is
>_110 gpm from LPSI 4" sch. 80/
considered pump performed quarterly 0.96** @ 110 gpm sufficient to flush the system piping.
- A Froude number slightly < 1.0 is sufficient to sweep the individual 2" HPSI recirculation lines into the common 4" lines.
- The piping run in the common 4" line is either horizontal or vertically upward. Per the NEI guidance, a Froude Number >
0.54 is required to move a gas void toward the downstream end of a horizontal pipe.
SI & CS test line to This discharge piping is 6" sch. 105 /
15 minutes the RWST flushed at 1500 gpm 3.68 @ 1500 gpm during plant heatup.
SDC Suction Lines This suction piping is 14" sch. 20 /
A flush time is not flushed at 3500 gpm 1.34 @ 3500 gpm specified in the during refueling outages procedure when SDC is in service, because water is flowing continuously while SDC is in service.
Both trains of LPSI are flushed prior to the end of a
___ refueling outage.
Serial No. 15-288A Docket Nos. 50-336/423 Attachment, Page 5 of 18 Location Flow Rate (gpm)
Pipe Size/Froude No.
Flush Time Chemical and While SDC is in service, a 3" sch 40 /
A flush time is not volume control portion of the SDC flow 1.98 @ 128 gpm specified in the system (CVCS) from the SDC heat procedure. This purification line to exchangers (HXs) is system flow path SDC suction header processed to the RCS can be placed in letdown HX, through the service for purification ion exchanger extended time and returns to the 14" periods during SDC suction line (128 refueling outages gpm).
which is considered sufficient to flush
___ the system piping.
For MPS3, a list of the locations that would be ensured to be gas free due to sufficient flow rate is provided in the table below. For each location, details of the corresponding flow rate, Froude number and length of time flow is maintained during gas removal (flush time) are also provided.
Location Flow Rate (gpm)
Pipe SizelFroude No.
Flush Time Quench Spray
>4000 gpm 14" sch. 40 /
A flush time is not System (QSS) suction 1.60 @ 4000 gpm specified in the piping and discharge procedure. The high piping through 12" sch. 40 I flow IST is recirculation line 2.00 @ 4000 gpm performed quarterly for each QSS pump.
The run time per pump necessary to obtain IST data is typically > 10 minutes, which is considered sufficient to flush the system
________________piping.
Serial No. 15-288A Docket Nos. 50-336/423 Attachment, Page 6 of 18 Location Flow Rate (gpm)
Pipe SizelFroude No.
Flush Time SDC suction and discharge piping to and from RCS The flow rate during plant shutdowns when SDC is in service is 2800 gpm per train (1400 gpm per cold leg). The flow path takes suction from the RCS hot legs through the residual heat removal (RHR) pumps and heat exchangers, then discharges back to the RCS cold legs.
The minimum flow rate during the emergency core cooling system (ECCS) flow test is 4000 gpm per train (2000 gpm per cold leg). When the system is used for ECCS, the LPSI flow path is from the RWST through the pumps and parallel through the HXs and the HXs bypass lines, then to the RCS cold legs for injection into the core.
16" sch. 40 /
1.15 @4000 gpm 14" sch. 40 /
1.12 @ 2800 gpm 1.60 @ 4000 gpm 12" sch. 40 /
1.40 @ 2800 gpm 2.00 @4000 gpm 12" sch. 160 /
2.15 @ 2800 gpm 10" sch. 40 /
2.20 @2800 gpm 3.15 @4000 gpm 10" sch. 140 /
1.55 @ 1400 gpm 2.21 @ 2000 gpm 10" sch. 160 /
3.32 @ 2800 gpm 4.75 @ 4000 gpm 6" sch. 160 /
5.51 @ 1400 gpm 8.16 @ 2000 gpm A flush time is not specified in the procedure because water is flowing continuously while SDC is in service.
Both trains of RHR are flushed prior to the end of a refueling outage.
Serial No. 15-288A Docket Nos. 50-336/423 Attachment, Page 7 of 18 Location Flow Rate (gpm)
Pipe SizelFroude No.
Flush Time Intermediate Head Safety Injection System (SIH) discharge piping from SIH pump to RCS through either cold legs or hot legs The minimum flow rate during the ECCS pump high flow test is 576 gpm (144 gpm per cold leg). The test is performed during refueling outages. Flow path is from the RWST through the Safety Injection pumps then to the RCS cold legs.
When operated for the quarterly pump IST surveillance, the minimum flow rate is 40.5 gpm per train.
6" sch. 40 /
1.59 @ 576 gpm 4" sch. 160 /
6.57 @ 576 gpm 2" sch. 160 /
9.74 @ 144 gpm 1.5" sch. 160/
4.89 @ 40.5 gpm (recirculation line) 3" sch. 160 /
0.91" @ 40.5 gpm (common recirculation line)
- A Froude number slightly < 1.0 is acceptable here because the piping run is either horizontal or vertically upward before entering the top of the RWST. Per the NEI guidance, a Froude Number > 0.54 is required to move a gas void toward the downstream end of a horizontal pipe.
A flush time is not specified in the procedure. The high flow IST test is performed for each SIH pump during refueling outages.
The run time per pump necessary to obtain 1ST data is typically > 10 minutes, which is considered sufficient to flush the system piping.
HPSI inside containment piping from penetration 51 to the RCS via CHS pumps
-I The minimum flow rate during the ECCS pump high flow test is 405 gpm (101.25 gpm per cold leg).
Note: Following DNC's response to GL 2008-0 1, flow rate for the high flow CHS pump IST has been increased to approximately 500 gpm.
4" sch. 160 /
4.62 @ 405 gpm 3" sch. 160 /
9.08 @ 405 gpm 1.5" sch. 160 /
12.22 @ 101.25 gpm A flush time is not specified in the procedure. The high flow IST test is performed for each CHS pump during refueling outages.
The run time per pump necessary to obtain IST data is typically > 10 minutes, which is considered sufficient to flush the system piping.
Serial No. 15-288A Docket Nos. 50-336/423 Attachment, Page 8 of 18
RAI 7
Many references are made to the effect that there are no known sources of gas that could contribute to a gas void in numerous components. A chemical sampling system that connects to multiple locations within containment has been known to cause gas accumulation due to multiple valve leaks.
This system is not mentioned in the licensee's application. Does Millstone Power Station Unit 2 (MPS2) or MPS3 have such a system? If so, what is the potential for gas accumulation and how is it addressed?
DNC Response DNC did not specifically address the chemical sampling systems at MPS2 and MPS3 as a potential source of gas intrusion during the GL 2008-01 response because the systems did not have a history of back leakage susceptibility.
The gas monitoring program was initially developed by focusing on preventing gas accumulation at known problem areas as well as those areas deemed vulnerable to gas accumulation.
New areas and/or additional systems would be handled via the corrective action program if they become self identified.
At MPS2, the Post Accident Sampling System (PASS) provides a sample pathway from the HPSI, LPSI and CS pump common 4-inch minimum flow recirculation line. The recirculation lines from each pump are 2-inch schedule (sch.) 80 before emptying into the common 4-inch sch. 80 recirculation line.
The individual 2-inch lines are dynamically swept at a Froude number _> 0.97 whenever the HPSI pumps are run on recirculation to the RWST and _> I whenever the LPSI or CS pumps are run on recirculation to the RWST. The common 4-inch minimum flow line is dynamically swept at a Froude number_> 0.96 whenever a LPSI pump is run on recirculation to the RWST.
The common recirculation line discharges to a tank at atmospheric pressure.
Therefore, the periodic dynamic sweep of these lines obviates the need for gas monitoring. Also, a non-PASS sampling system connects to the 14-inch LPSI pump SDC suction line.
This pipe section is dynamically flushed during refueling outages when SDC is first placed in-service. Any potential gas voids would be removed at that time.
This pipe section is currently exempt from the quarterly gas monitoring surveillance since it is isolated without head pressure during normal plant operation.
However, the SDC suction piping will be added to the gas monitoring surveillance upon NRC approval of the LAR.
At MPS3, the PASS provides a sample pathway from the ECCS cross-over piping (i.e.,
post LOCA long term recirculation piping between the Containment Recirculation Spray System (RSS) pumps and the ECCS pumps). This piping location is currently included in the current gas monitoring surveillance that supports TS 4.5.2.b.1.
The Reactor Plant Sampling system provides a sample pathway from the Residual Heat Removal (RHR) system pump minimum flow line.
This piping is in service during
Serial No. 15-288A Docket Nos. 50-336/423 Attachment, Page 9 of 18 quarterly RHR pump surveillance tests. A gas void originating here would be swept into the main 14-inch RHR pump suction header during the 1ST and from there voids would collect in a 12-inch vertical take-off from the RWST. This piping section is inspected for gas following each quarterly RHR pump IST and is also included in the current gas monitoring surveillance that supports TS 4.5.2.b.1.
RAI 8
The reported April 6, 2014, 'B' LPSI pump cavitation was attributed to a previously recognized discharge side void.
Please address how this interacted with behavior associated with a common two inch discharge line where the pump that has a lower discharge pressure capability may no longer pro vide flow.
DNC Response The event occurred during the warm-up stages prior to placing the SDC system in service, which only requires a single LPSI pump to be running at a very low flow rate.
Therefore, the concern associated with interaction between two pumps would not exist.
Furthermore, the condition is not a concern for an ECCS event where two LPSI pumps could be operating simultaneously since the LPSI system alignment is different (i.e., an open system flow path from the RWST to the RCS where one or both LPSI pumps would sweep a void in the discharge piping into the RCS). The LPSI system alignment during the actual event (placing the SOC system in service) operated a single LPSI pump in a closed loop system.
RAI 9
Please provide the void surveillance history of MPS2 starting at January 1, 2008.
Include the following:
- a. The surveillance frequency.
- b. For each discovered void, provide the mode, date, location, void quantity, void acceptance criterion, post void action (location restored to a water-solid condition) and reason for discovery of the void (examples include routine surv'eillance, accumulator behavior, reactor coolant leakage). If the void quantity exceeded the void acceptance criterion, then provide the disposition with respect to the impact on operability.
- c. A statement that if a void is not identified in Item b, then routine surveillances determined that there was no void.
- d. The total number of surveillances conducted.
- e. Monitoring of equipment such as accumulators or reactor coolant system leakage and follow-up from outages with respect to void assessment.
Serial No. 15-288A Docket Nos. 50-336/423 Attachment, Page 10 of 18 DNC Response The gas monitoring surveillance program at MPS2 began in March 2010.
The surveillance data from March 2010 through June 2015 is provided in the table below.
- a. The gas monitoring surveillance frequency at MPS2 is performed every 92 days.
In the event of an active gas intrusion mechanism or a failed surveillance, the surveillance frequency at that location would be increased. Once resolved, the frequency would be returned to every 92 days.
- b. Details of discovered voids are provided in the table below.
Since March, 2010, gas accumulation at MPS2 has been predominantly found in two locations. The first location is the LPSI pump common discharge header at the four 6" cold-leg loop injection lines (i.e., UT Points 20, 21, 22, and 23). This location is the high point of the LPSI system piping just before it combines with HPSI and just outside the containment penetrations.
The four locations are upstream of their respective normally closed isolation valve in a short horizontal pipe run (typically one to two feet in length). These areas are prone to collecting minor gas voids over time.
The second location is the CS pump discharge headers [UT Point 26 (B Train) and UT Point 27 (A Train)] just prior to their containment penetrations (see the response to Question 9.e).
- c. Routine surveillance is performed at 27 total locations every 92 days. There are 19 locations in the A Train and common piping (four are located in pump suction piping and 15 are located in pump discharge piping). There are eight locations in the B Train (four are located in pump suction piping and four are located in pump discharge piping).
Per the routine 92-day surveillance frequency, voids were identified during the surveillance dates noted with an asterisk. For the dates with no asterisk, routine surveillance determined there were no voids at any of the surveillance locations.
Train A Train B 3/16/10*
3/9/10*
6/8/10*
6/22/10*
8/31/10*
8/17/10*
12/20/10*
11/9/10 2/15/111*
2/3/11 5/10/11 7/19/111 8/2/11 10/13/111 11/2/11 1/3/12*
1/18/12*
3/27/12 4/17/12 6/25/12 7/10/12 9/18/12
Serial No. 15-288A Docket Nos. 50-336/423 Attachment, Page 11 of 18 9/25/12 12/4/12 12/18/12*
2/26/13*
3/12/13 5/21/13*
6/4/13 8/13/13*
8/27/13 11/5/13 11/19/13 1/27/14 2/11/14 5/17/14 5/16/14*
7/29/14 7/28/14*
10/6/14 10/23/14*
12/29/14 10/31/14*
3/24/15 1/16/15*
6/15/15 4/6/15*
6/29/15*
Details of the void locations are provided in the table below.
- d. For each train, the total number of routine surveillances conducted since March 2010 (based on a 92-day frequency) is approximately 24. In addition, there have been approximately 108 surveillances performed at certain locations as either follow-up or trending of recurring problem areas.
Surveillance results which identified gas voids are provided in the table below.
- e. Gas accumulation discovered on May 21, 2013 at UT Point 26 (CS header - B Train) was a result of SIT back leakage across multiple valves. The common RWST return piping had become pressurized due to the SIT back leakage. This caused back leakage through a 1" line into the CS header just outside the containment penetration.
Because the back leakage could not be corrected immediately, daily monitoring and venting of the CS header was necessary for the first week, then weekly for the next 46 weeks until the back leakage was corrected during the spring 2014 MPS2 refueling outage. Refer to UT Point 26 during operating cycle 22 in the table below.
On May 16, 2014, during start-up from the spring 2014 refueling outage, gas accumulation was discovered at UT Point 27 (CS header - A Train). This void was due to improper fill and vent of the A Train CS. After the void was removed, continual degassing of aerated water at that location required daily monitoring and venting of the CS header for the first week, then weekly for the next 48 weeks.
Once the trending data showed a stable void volume, the monitoring frequency was changed to every two weeks.
The remaining air void is understood to be unventable air due to an unfavorably sloped pipe. This void will continue to be monitored until it is ultimately removed during the fall 2015 MPS2 refueling outage.
Gas voids at this location are not typical when the CS discharge piping fill and vent process is properly performed following refueling outages. Refer to UT Point 27 during operating cycle 23 in the table below.
Serial No. 15-288A Docket Nos. 50-336/423 Attachment, Page 12 of 18 Cycle 23 Date Location Void Vol.
Allowable Notes Surveillance Reason for Disposition and (ft3)
Vol. (ft3)
Frequency Discovery with Train Respect to Impact on Operability 6/29/15 UT Point 20 - LPSI 0.017 0.128 Mode 1. Source was 92 days Routine Void Train A discharge degassing after securing surveillance volumes UT Point 21-LPSI 0.002 0.244 shutdown cooling in within discharge Refueling Outage 22 -
operability UT Point 23-LPSI 0.020 0.147 Location restored to water-limits discharge filled condition.
UT Point 27-CS 0.025 2.57 Mode 1. Source was discharge degassing after securing shutdown cooling in Refueling Outage 22 -A portion of the piping is unventable due to pipe
____________________slope.
5/1 9/1 4-UT Point 27-CS 0.071 -
2.57 Mode 1. Source was Daily Increased Void volume 6/15/15 discharge 0.161 degassing after securing changed to surveillance within Train A shutdown cooling in Bi-weekly frequency operability Refueling Outage 22 -The after exit limits recurrence of small gas from voids is a continuation of Refueling the improper fill & vent that Outage 22 occurred on 5/1 6/1 4. A portion of the piping is unventable due to pipe
________________________slope.
Serial No. 1 5-288A Docket Nos. 50-336/423 Attachment, Page 13 of 18 Date Location 1Void Vol.
Allowable Notes Surveillance Reason for~ Disposition and (ft3)
Vol. (ft3)
Frequency Discovery with I
I Impact on I I IOperability 4/6/15 UT Point 20 - LPSI 0.026 0.128 Mode 1. Source was 92 days Routine Void volume Train A discharge degassing after securing surveillance was within UT Point 22 - LPSI 0.037 0.129 shutdown cooling in operability discharge Refueling Outage 22 -
limits UT Point 23 - LPSI 0.030 0.147 Location restored to water-discharge filled condition.
1/16/15 UT Point 21 - LPSI 0.007 0.244 Mode 1. Source was 92 days Routine Void volume Train A discharge degassing after securing surveillance was within shutdown cooling in operability Refueling Outage 22 -
limits Location restored to water-filled condition.
10/31/14 UT Point 20 - LPSI 0.010 0.128 Mode 1. Source was 92 days Routine Void volume Train A discharge degassing after securing surveillance was within UT Point 22 - LPSI 0.006 0.129 shutdown cooling in operability discharge Refueling Outage 22 -
limits UT Point 23 - LPSI 0.025 0.147 Location restored to water-discharge filled condition.
10/23/14 UT Point 20 - LPSl 0.013 0.128 Mode 1. Source was 92 days Routine Void volume Train A discharge degassing after securing surveillance was within UT Point 21 - LPSI 0.069 0.244 shutdown cooling in operability discharge
___________Refueling Outage 22 -
limits UT Point 22 - LPSI 0.048 0.129 Location restored to water-discharge filled condition.
UT Point 23 - LPSI 0.025 0.147
_______discharge 7/28/14 UT Point 20 - LPSI 0.036 0.128 Mode 1. Source was 92 days Routine Void volume Train A discharge
______degassing after securing surveillance was within UT Point 22 - LPSl 0.122 0.129 shutdown cooling in operability discharge Refueling Outage 22 -
limits
Serial No. 15-288A Docket Nos. 50-336/423 Attachment, Page 14 of 18 Date Location Void Vol.
Allowable Notes Surveillance Reason for Disposition and (ft 3)
Vol. (ft3)
Frequency Discovery with Train Respect to Impact on Operability UT Point 23 - LPSI 0.015 0.147 Location restored to water-discharge filled condition.
5/17/14 UT Point 25 -CS 0.031 2.57 Mode 1. Source was Follow-up Increased Void volume Train B discharge improper fill and vent after surveillance was within Refueling Outage 22 -
frequency operability Location restored to water-after exit limits filled condition.
from Refueling Outage 22 5/16/14 UT Point 20 - LPSI 0.006 0.128 Mode 2. Source was 92 days Routine Void volume Train A discharge degassing after securing surveillance was within UT Point 21 - LPSI 0.025 0.244 shutdown cooling in operability discharge Refueling Outage 22 -
limits UT Point 22 - LPSI 0.027 0.129 Location restored to water-discharge filled condition.
UT Point 23 - LPSI 0.042 0.147 discharge UT Point 25 - CS 0.343 2.57 Mode 2. Source was The ATrain discharge improper fill and vent after of CS was UT Point 27 - CS 5.286 2.57 Refueling Outage 22 -
declared discharge Location restored to water-inoperable filled condition.
due to accumulated gas volume at Point 25 and Point 27 exceeding acceptance criteria of
___2.57
Serial No. 15-288A Docket Nos. 50-336/423 Attachment, Page 15 of 18 Cycle 22 Date Location Void Vol.
Allowable Notes Surveillance Reason for Disposition (ft3)
Vol. (ft3)
Frequency Discovery with Respect to Impact on Operability 5/22/1 3-UT Point 26-CS 0.088 -
2.57 Mode 1. Source was SIT Daily Increased Void 3/31/14 discharge 0.161 back leakage across changed to surveillance volume was Train B multiple valves into the B Bi-weekly frequency within Train CS discharge header -
operability Location restored to water-limits filled condition each instance.
5/21/13 UT Point 26 - CS 6.557 2.57 Mode 1. Source was SIT 92 days Routine B Train of Train B3 discharge back leakage across surveillance CS multiple isolation valves, declared Location restored to water-inoperable filled condition.
2/26/13 UT Point 26 - CS 0.341 2.57 Mode 1. Source was 92 days Routine Void Train B discharge considered a one-time surveillance volume was anomaly that was attributed within to minor system degassing -
operability Location restored to water-limits filled condition.
12/18/12 UT PointS5-HPSl 0.049 0.334 Mode 1. Source was 92 days Routine Void Train A suction improper fill and vent after surveillance volume was HPSI pump on-line within maintenance - Location operability restored to water-filled limits condition.
Serial No. 15-288A Docket Nos. 50-336/423 Attachment, Page 16 of 18 Cycle 21 Date Location Void Vol.
Allowable* Notes Surveillance Reason for Disposition and (ft3)
Vol. (ft3)
Frequency Discovery with Train Respect to Impact on Operability 1/18/12 UT Point 22-LPSI 0.037 0.129 Mode 1. Source was minor 92 days Routine Void Train A discharge system degassing - Location surveillance volume was restored to water-filled within condition.
operability limits 1/3/12 UT Point 11 - HPSI 0.059 0.207 Mode 1. Source was 92 days Routine Void Train B discharge improper fill and vent after surveillance volume was HPSI pump on-line within maintenance - Location operability restored to water-filled limits condition.
Cycle 20 Date Location Void Vol.
Allowable
-Notes Surveillance Reason for Disposition and (ft3)
Vol. (ft3)
Frequency Discovery with Impact on
_______I______________
aOerablit 2/15/11 UT Point 20 - LPSI 0.026 0.128 Mode 1. Source was 92 days Routine Void Train A discharge degassing after securing surveillance volume was shutdown cooling in within Refueling Outage 19 -
operability Location restored to water-limits
____ _____ filled condition.
Serial No. 15-288A Docket Nos. 50-336/423 Attachment, Page 17 of 18 Date TLocation Void Vol.
Allowable~ Notes Surveillance Reason for Disposition and (ft3)
Vol. (ft3)
Frequency Discovery with
{mpact on 12/20/10 UT Point 20 - LPSI 0.013 0.128 Mode 1. Source was 92 days Routine Void Train A discharge
______degassing after securing surveillance volume was UT Point 21 - LPSI 0.060 0.244 shutdown cooling in within discharge
___________Refueling Outage 19 -
operability UT Point 23 - LPSI 0.011 0.147 Location restored to water-limits discharge filled condition.
8/31/10 UT Point 22 - LPSI 0.005 0.129 Mode 1. Source was 92 days Routine Void Train A discharge
______degassing after securing surveillance volume was UT Point 23 - LPSI 0.005 0.147 shutdown cooling in within discharge Refueling Outage 19 -
operability Location restored to water-limits
________filled condition.
8/17/10 UT Point 26 - CS 0.088 2.57 Mode 1. Source was 92 days Routine Void Train B discharge degassing after securing surveillance volume was shutdown cooling in within Refueling Outage 19 -
operability Location restored to water-limits filled condition.______
6/22/10 UT Point 26 -CS 0.123 2.57 Mode 1. Source was 92 days Routine Void Train B discharge degassing after securing surveillance volume was shutdown cooling in within Refueling Outage 19-operability Location restored to water-limits filled condition 6/8/10 UT Point 20 - LPSI 0.024 0.128 Mode 1. Source was 92 days Routine Void Train A discharge
______degassing after securing surveillance volume was UT Point 21 - LPSI 0.012 0.244 shutdown cooling in within discharge Refueling Outage 19 -
operability Location restored to water-limits filled condition.
Serial No. 15-288A Docket Nos. 50-336/423 Attachment, Page 18 of 18 Date Location Void Vol.
Allowable Notes Surveillance Reason for Disposition and (ft3)
Vol. (ft3)
TFrequency Discovery with Train Respect to I
Impact on 3/16/10 UT Point 20 - LPSI 0.022 0.128 Mode 1. Source was 92 days Routine Void Train A discharge degassing after securing surveillance volume was UT Point 21 - LPSI 0.046 0.244 shutdown cooling in within discharge Refueling Outage 19 -
operability UT Point 22 - LPSI 0.042 0.129 Location restored to water-limits discharge filled condition.
UT Point 23 - LPSI 0.011 0.147 discharge 3/9/10 UT Point 26 - CS 0.341 2.57 Mode 1. Source was 92 days Routine Void Train B discharge degassing after securing surveillance volume was shutdown cooling in within Refueling Outage 19 -
operability Location restored to water-limits
____ _____ filled condition.
_