ULNRC-05995, Application for Amendment to Facility Operating License NPF-30, Revision to Technical Specification 3.7.9

Application for Amendment to Facility Operating License NPF-30, Revision to Technical Specification 3.7.9

ML13163A008
Person / Time
Site:	Callaway
Issue date:	06/11/2013
From:	Maglio S Ameren Missouri, Union Electric Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
ULNRC-05995
Download: ML13163A008 (8)

Text

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WAmeren Callaway Plant MISSOURI June 11, 2013 ULNRC-05995 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001 10 CFR 50.90 Ladies and Gentlemen:

DOCKET NUMBER 50-483 CALLAWAY PLANT UNION ELECTRIC CO.

APPLICATION FOR AMENDMENT TO FACILITY OPERATING LICENSE NPF-30 (TAC NO. MF0378, LDCN 12-0015)

REVISION TO TECHNICAL SPECIFICATION 3.7.9

References:

1. ULNRC-05867 dated December 13, 2012, Revision to Technical Specification 3.7.9 (LDCN 12-0015)

2. NRC Request for Additional Information, Carl F. Lyon (NRC) to Adam C. Heflin (Union Electric Company),

dated May 13, 2013 In Reference 1 above, Ameren Missouri (Union Electric Company) submitted an application for amendment to Facility Operating License Number NPF-30 for the Callaway Plant. The amendment application addresses a non-conservative Technical Specification as discussed in NRC Administrative Letter 98-1 0, "Dispositioning of Technical Specifications That Are Insufficient To Assure Plant Safety."

The amendment application proposes changes to Technical Specification (TS) 3.7.9, "Ultimate Heat Sink (UHS)," to incorporate more restrictive UHS level and pond temperature limits which are specified in Surveillance Requirements (SRs) 3. 7. 9.1 and 3.7.9.2, respectively. In addition, new SR 3.7.9.4 would be added to verify that the UHS cooling tower fans respond appropriately to automatic start signals.

PO Box 620 Fulton, MD 65251 AmerenMissouri.com

ULNRC-05995 June 11,2013 Page 2 In Reference 2 above, the NRC requested additional information to complete their review, with a response within 30 days. The Enclosure to this letter provides the requested information. No commitments are contained in this letter.

If you have any questions on this amendment application, please contact me at (573) 676-8719 or Mr. Tom Elwood at (314) 225-1905.

I declare under penalty of perjury that the foregoing is true and correct.

Very truly yours, Executed on: la f I I /2.-o ~

~~~~0 Regulatory .Affairs Manager GGY/nls

Enclosure:

RAI Response

ULNRC-05995 June 11, 2013 Page 3 cc:

U.S. Nuclear Regulatory Commission (Original and 1 copy)

Attn: Document Control Desk Washington, DC 20555-0001 Mr. Arthur T. Howell Regional Administrator U.S. Nuclear Regulatory Commission Region IV 1600 East Lamar Boulevard Arlington, TX 76011-4511 Senior Resident Inspector Callaway Resident Office U.S. Nuclear Regulatory Commission 8201 NRC Road Steedman, MO 65077 Mr. Fred Lyon Project Manager, Callaway Plant Office ofNuclear Reactor Regulation U.S. Nuclear Regulatory Commission Mail Stop 0-8B 1 Washington, DC 20555-2738

ULNRC-05995 June 11, 2013 Page4 Index and send hardcopy to QA File A160.0761 Hardcopy:

Certrec Corporation 4150 International Plaza Suite 820 Fort Worth, TX 76109 (Certrec receives ALL attachments as long as they are non-safeguards and may be publicly disclosed.)

Electronic distribution for the following can be made via Tech Spec ULNRC Distribution:

A. C. Heflin F. M. Diya C. 0. Reasoner III B. L. Cox L. H. Graessle J. S. Geyer S. A. Maglio Corporate Communications NSRB Secretary T. B. Elwood G. G. Yates STARS Regulatory Affairs Mr. John O'Neill (Pillsbury, Winthrop, Shaw, Pittman LLP)

Missouri Public Service Commission Ms. Leanne Tippett Mosby (DNR)

Enclosure Page 1 of 4 By application dated December 13, 2012 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML12349A321), to the U.S. Nuclear Regulatory Commission (NRC), Union Electric Company (dba Ameren Missouri, the licensee) submitted a license amendment request to incorporate more restrictive ultimate heat sink (UHS) pond level and temperature limits which are specified in Surveillance Requirements (SRs) 3. 7. 9.1 and 3. 7. 9.2, respectively. In addition, new SR 3.7.9.4 would be added to verify that the UHS cooling tower fans respond appropriately to automatic start signals.

The NRC staff has determined that the additional information requested below is needed to complete its review.

Question:

1. The licensee stated on page 4 of the application that the UHS minimum water depth of 831.25 feet, as stated in the Callaway Safety Evaluation Report (SER), NUREG-0830, Supplement 4, Section 2.4.4, was previously accepted by the staff in 1984. However, due to the licensee's reassessment of the UHS based upon its National Pollutant Discharge Elimination System (NPDES) Permit, the licensee now proposes to increase the UHS minimum water depth to 834 feet.

Please provide justification for the reassessment of the UHS minimum water level from 831.25 feet to 834 feet, since it is not sufficiently described in the application. Describe any physical changes to the UHS design, analysis methodology, or operation that would allow the calculation of the UHS freeboard to show that UHS discharge at nearly 835.83 feet is now negligible.

Response

The basis behind the requested change to SR 3.7.9.1 (from 831.25 feet to 834 feet) is discussed on pages 11-12 of the License Amendment Request (LAR) Enclosure, Evaluation Section 3.0, with respect to the Calculation EF-123 input assumptions, and on page 23 of Evaluation Section 4.2 (response to 10 CFR 50.92 Question 3).

There have been no design changes to the physical dimensions of the UHS. Pages 5 and 6 of the LAR Enclosure provide specific details of the design changes that were implemented via modification package (MP) 11-0004 during the last operating cycle (Cycle 19) under 10 CFR 50.59. The nominal target level of the UHS retention pond and the non-safety related alarm setpoints (both high level and low level) were changed. An environmental evaluation was performed for MP 11-0004 which concluded that any risk of an overflow from the UHS, when operated within the band between the low and high level alarms (i.e., between the main control board annunciator window 55D low and high level alarms driven from level indicating switch EFLIS0027, a band ranging from 16'- 8" to 17'-10"), is extremely small.

Outfall17 (UHS spillway) is designated as a no discharge outfall. The increase in water elevation reduces the spillway freeboard thus decreasing the margin available on an NPDES

Enclosure Page 2 of4 permitted outfall.

MP 11-0004 Environmental Evaluation Summary The design basis maximum level for the UHS has always been 18 feet (1995'- 6" using the original SNUPPS power block elevation measuring convention) with an unchanged, original design spillway height of 18 feet 6 inches ( 1996'- 0"). The nominal target UHS level is now 17 feet ( 1994'- 6") with low and high alarms establishing a normal operating band between 16 feet 8 inches (1994'- 2") and 17 feet 10 inches (1995'- 4"). The high level alarm provides a 2-inch band (for level switch tolerance) below the UHS design basis maximum level of 18 feet.

Callaway Plant's current NPDES Permit (M0-0098001) does not allow discharges from the UHS spillway. Outfall 017 (the Ultimate Heat Sink) is a no discharge outfall. If the UHS were to overflow, that discharge would go to Stormwater Pond Outfall #011. This would represent a noncompliance with the NPDES Permit. However, the risk of any overflow from the UHS is extremely small. Operation at the high level alarm of 17'- 10" has been evaluated and would require sustained winds of 40 mph from the southwest producing waves of 8.4", in conjunction with instrument error (2" switch tolerance in the positive direction), in order to potentially push a small quantity of water over the spillway. Winds from other directions would have a reduced risk of overflow or, for some directions, no risk of overflow due to the reduced cross section for wind action and the lack of a spillway on the other three sides. The highest sustained winds recorded at the plant over the past two years were approximately 30 mph. Therefore, any risk of overflow from the UHS operating at the high alarm level of 17'- 10" is negligible.

The environmental evaluation concluded that MP 11-0004 does not involve a change that would cause a significant environmental impact previously evaluated in the Environmental Report (ER) or Final Environmental Statement- Operating License Stage (FES-OL). MP 11-0004 returned the operation of the UHS pond to its original operating design level. The only possible impact was determined to be an insignificant risk for a discharge from the UHS pond to Stormwater Outfall #011. This would result in a noncompliance with the current NPDES Permit. However, the likelihood of any overflow or spillage from the UHS is extremely remote as described above.

Makeup to the UHS pond and Essential Service Water system is from the plant service water system (clarified and treated river water) with some addition by rainfall. Chemical treatment is routinely completed for prevention of micro fouling and macro fouling in this system.

UHS Level Design and Alarm Changes UHS level is monitored and indicated by two non-safety related instrument loops, EFL-0027 A, ESW Pumphouse Forebay Level (Pump 'A') and EFL-0027, ESW Pumphouse Forebay Level (Pump 'B'). Both instrument loops measure from minus 232 inches to plus 8 inches level and indicate 0-100%. Both of these instrument loops feed computer points. Only the EFL-0027 instrument loop feeds high and low level alarms. This instrumentation has no safety function.

Enclosure Page 3 of4 Instrument loop EFL-0027 consists of a level element and indicating switch (EFLE0027, EFLIS0027). The switch feeds Main Control Board (MCB) Annunciator Window 55D, UHS Pond Level High or Low. It also feeds computer point EFL0027 (low level) and computer point EFL00278 (high level). The low setpoint actuates at 1994'- 2" and the high setpoint actuates at 1995'- 4" with a switch tolerance of plus or minus 2 inches. Both setpoints have a reset differential of2.4". The high setpoint is designed to prevent UHS overfilling. Overfilling the UHS would lead to an NPDES violation. This setpoint is also used to protect the High Density Polyethylene (HDPE) underground ESW piping (installed during the winter 2008- spring 2009).

Another function of the high alarm setpoint is to assure that water remains in the heated UHS Cooling Tower (CT) basin sump to assure the basin floor doesn't freeze. The low setpoint alarm alerts the control room operators that the UHS retention pond level is approaching the Technical Specification 3.7.9 minimum level.

The table below summarizes the UHS level setpoint changes.

UHS Level Setpoint Changes Previous Value Current Value Per Limit Before MP 11-0004 MP 11-0004 Differential HDPE Maximum Allowed 19' Unchanged NIA Level (1996'- 6")

UHS CT Sump Height 19' Unchanged NIA (1996'- 6")

Spillway Height 18'- 6" Unchanged NIA (1996' - 0")

Design Basis Maximum 18' Unchanged NIA Level (1995'- 6")

EFLIS0027 17'- 6" 17'- 10" 6" High Setpoint (1995') (1995'-4") (Note 1)

EFLIS0027 15'- 8" 16'- 8" 5.0" Low Setpoint (1993'- 2") (1994'- 2") (Note 2)

Required TS Minimum 13'- 3" 16'- 0" NIA Level ( 1990'- 9") (Note 2)

Pond Bottom 0' Unchanged NIA (1977'- 6")

Enclosure Page 4 of4 Notes:

1. 18'- 6" (Spillway Height)- 17'- 10" (high level alarm setpoint)- 2.0" (switch tolerance)= 6".

The normal UHS operating band will be set between 16'- 8" and 17'- 10" with a target nominal depth of 17'.

2. 16'- 8" (low level alarm setpoint)- 2.0" (switch tolerance)- 1" (wave action)- 16' (proposed TS 3.7.9 minimum level)= 5".

1" wave action has been added to the margin determination for conservatism. The level sensors are isolated from wind effects.

The following slide was presented during the meeting between Ameren Missouri and the NRC on August 29, 2012. It provides a visual aid for understanding the above information. There is an 18-inch difference between the nominal target level at which the UHS retention pond will be maintained and the elevation of the UHS spillway. Ameren Missouri believes a combination of this elevation difference, the 24-hour performance ofSR 3.7.9.1 to verify UHS level, and operator action taken in response to a high level alarm will prevent NPDES violations.

Site Layout

- Maximum Level

_ _ ,.,_.,--Elevation of Spillway

- Proposed Target Level

- Proposed Tech. Spec.

UHS Cooling Tower ~

3.25' -Current Tech. Spec.

I

- - -~

UHS Retention Pond

- Bottom of Pond (Reference Level)