ML14133A653
| ML14133A653 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 05/13/2014 |
| From: | Andrew Hon Plant Licensing Branch II |
| To: | James Shea Tennessee Valley Authority |
| Andy Hon | |
| References | |
| TAC MF2852, TAC MF2853 | |
| Download: ML14133A653 (6) | |
Text
Hon, Andrew To:
Cc:
Subject:
Mr. Joseph W. Shea Shea, Joseph W Owshea@tva.gov)
Lee, Henry (hleeO@tva.gov); Schrull, Edward Dustin (edschrull@tva.gov); Regner, Lisa; Purciarello, Gerard; Saba, Farideh SEQUOYAH NUCLEAR STATION, UNIT 1-REQUEST FOR ADDITIONAL INFORMATION RELATED TOLAR to Revise Ultimate Hear Sink Related Tech Spec.
Vice President, Nuclear Licensing Tennessee Valley Authority 6A Lookout Place 1101 Market Street Chattanooga, TN 37402-2801
SUBJECT:
SEQUOYAH NUCLEAR PLANT, UNITS 1 AND 2,- REQUEST FOR ADDITIONAL INFORMATION RELATED TO LICENSE AMENDMENT REQUEST TO REVISE TECHNICAL SPECIFICATION ON ULTIMATE HEAT SINK (TAC NOS. MF2852 AND MF2853)
Dear Mr. Shea:
By letter dated October 2, 2013, you submitted an application to revise technical specification 3.7.5, "Ultimate Heat Sink," with temperature limitations supporting alternate Essential Raw Cooling Water loop alignments.
The U.S. Nuclear Regulatory Commission (NRC) staff is reviewing your submittal and has determined that additional information is required to complete the review. The specific information requested is addressed below. The proposed questions were discussed by telephone with your staff on April 24, 2014. Your staff confirmed that these questions did not include proprietary or security-related information and agreed to provide a response by July 24, 2014 to this request for additional information (RAI).
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The NRC staff considers that timely responses to RAis help ensure sufficient time is available for staff review and contribute toward the NRC's goal of efficient and effective use of staff resources. If circumstances result in the need to revise the requested response date, please contact me at (301) 415-8480 or via e-mail Andrew. Hon@nrc.gov.
Docket Nos. 50-327 and 50-328 Accession No. ML14133A653 Sincerely, RIA Andrew Hon, Project Manager Plant Licensing Branch 11-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation 2
REQUEST FOR ADDITIONAL INFORMATION LICENSE AMENDMENT REQUEST TO CHANGE TO TECHNICAL SPECIFICATION 3.7.5. "ULTIMATE HEAT SINK" TENNESSEE VALLEY AUTHORITY SEQUOYAH NUCLEAR PLANT (WBN), UNIT 1 AND UNIT 2 DOCKET NOS. 50-327 AND 50-328
RAI-1
BACKGROUND The License Amendment Request (LAR) states, "With one unit shutdown and the Reactor Coolant System (RCS) temperature < 200 degrees Fahrenheit (°F), minimum combined safety requirements for one "accident" unit and one "non-accident" unit, or two "non-accident" units, are met by only one pump on one plant train when the Essential Raw Cooling Water (ERCW) system is aligned as delineated in the proposed Technical Specification (TS) Bases."
Assume the following simultaneous plant conditions:
The plants are in either an Outage 1 or Outage 3 scenario as defined in your LAR where one unit is in Mode 5 and the other unit has a Loss-Of-Coolant Accident (LOCA).
a) The Mode 5 shutdown unit has been brought to Mode 5 in the fastest allowed time by procedure where the remaining decay heat is at its maximum.
b) Decay heat is at maximum possible considering all times in core life.
c) The assumed single failure is the A Train ERCW leaving only B Train ERCW components where the only Component Cooling System (CCS) Heat Exchanger (HX) receiving ERCW flow is 081/082.
Request a) For the above conditions, please identify the total required ERCW flow rate necessary to the Component Cooling System (CCS) HX in order to mitigate a LOCA in one unit and simultaneously remove maximum decay heat in the other unit that has just entered Mode 5. Please identify all assumptions.
b) For the above conditions, please explain how the CCS HX 081/082 is able to mitigate the LOCA in one unit and keep the other unit in Mode 5 in the above described conditions.
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RAI-2 BACKGROUND Final Safety Analysis Report (FSAR) Section 9.2.2.2 on ERCW states that the primary cooling source for each Diesel Generator (DG) heat exchanges (HXs) is from the Unit 1 headers. Each diesel also has an alternate supply from the unit 2 headers of the opposite train.
Request a)
Describe how the primary cooling source of ERCW is supplied to each DG by describing which ERCW valves are opened automatically and manually upon DG startup.
b)
Similarly describe how the alternate supply of ERCW is supplied to each DG and which ERCW valves are opened automatically and manually upon DG startup.
c)
Describe how the alternate supply of ERCW replaces the primary source of ERCW.
RAI-3 BACKGROUND TVA proposed ERCW lineups to allow Strainer Outage and has performed calculations stating that there is sufficient ERCW flow to mitigate a Design-Basis Accident (DBA) in one unit and maintain the non-accident unit in hot standby. In a Request for Additional Information (RAI) dated November 11, 2013, the U.S. Nuclear Regulatory Commission (NRC) staff asked the licensee to describe calculations that show that the non-accident unit can be cooled down in accordance with the guidance of Regulatory Guide 1.27, which was specified in the original submittal dated October 2, 2013. SQN stated in their response dated December 11, 2013 that "because the SQN Updated Final Safety Analysis Report (UFSAR) does not place any limit on cool down time for the non-accident unit, Tennessee Valley Authority (TVA) does not have formal calculations that demonstrate cool down time.
SQN TS 3.7.4, "Essential Raw Cooling Water System," requires at least two independent essential raw water cooling loops to be OPERABLE. Both Units 1 and 2 have these TS. If any ERCW loop is inoperable the TS ACTION requires cold shutdown within the specified times.
In the Strainer Outage Cases, a DBA is assumed in one unit with a single failure of one of the ERCW loops.
With ERCW being a shared system, the failure of one ERCW loop places the non-accident unit in TS 3.7.4 ACTION where cold shutdown is required within the specified time.
Request Identify and discuss additional action needed to confirm that SQN can comply with TS 3.7.4 ACTION for the non-accident unit for both the Strainer Outage Cases and now during current operation.
RAI-4 BACKGROUND TVA has listed in the LAR that each Emergency Diesel Generator (EDG) HX requires 522 GPM of ERCW at arF temperature.
Request Please provide the vendor data sheets for the EDGs that list:
a) the design flow rate and temperature for the ERCW that cools the EDG HXs, and b) the corresponding fouling factors and heat transferred for the EDG HXs cooled by ERCW.
Provide justification for any changes in the data of the vendor data sheet used to determine that 522 GPM ERCW is the required cooling water flow rate at arF.
RAI-5 BACKGROUND 4
TVA has proposed that the change to Limiting Condition for Operation (LCO) 3.7.5 for Unit 1 and Unit 2 be consistent with Improved Standard TSs (NUREG-1431), such that specifics associated with Ultimate Heat Sink (UHS) temperature limitations are relocated to the Surveillance Requirements (SRs).
TS 3.7.9 of NUREG 1431 require the licensee to verify UHS temperature once per hour when the UHS temperature approaches within several degrees of the maximum allowed UHS temperature based on limitations of equipment.
TVA appeared to have proposed change to the SRs requires UHS temperature verification at least once every 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> no matter what the UHS temperature, even at the maximum allowed temperature.
Request Please clarify SR 4.7.5.1 and/or TS 3.7.5 such that when ERCW supply temperature is within several degrees of the maximum temperature limits that verification of UHS temperature is hourly to be consistent with NUREG 1431.
RAI-6 BACKGROUND The LAR forTS Bases 3/4.7.4, "ERCW System," in discussing OPERABILITY uses the term "single active failure."
Section 5 of the licensee's submittal lists GDC 44 as an applicable regulatory requirement. GDC 44 requires consideration of a "single failure" which includes a single passive electrical failure.
The TS Bases appeared not to be consistent with GDC 44.
Request Please clarify the TS Bases to include a single passive electrical failure.
RAI-7 BACKGROUND Outage 3 as described in Table 4.2-61ists the 1A and 1B EDGs as shutdown. For Outage 3, Tables 4.2-12 and 4.2-13 show EDGs 2A and 2B with ERCW flow and EDGs 1A and 1 B without ERCW -flow; this is consistent with Table 4.2-6 for Outage 3. With EDGs 1A and 1 B without ERCW flow, the NRC staff notes that this lineup does not meet the LCO forTS 3.8.1.2, Electrical Power Systems Shutdown, for Unit 1.
Request Please identify all other TSs whose LCOs are not met for Outage 3; then also for Outage 1; and all Strainer Outage cases. Identify required TS actions and equipment to be declared INOPERABLE for each LCO not met.
RAI-8 Request Please clarify the information presented in Tables 4.2-12 and 4.2-13 by answering the following questions:
a) Each table shows 1 EDG receiving ERCW flow. With the loss of either the A train or the B train as the single failure, does that mean 1 EDG is both mitigating the LOCA in one unit and keeping the non-accident unit in Mode 5? Explain.
b) Clarify the required ERCW flow for each EDG. Tables 4.2-12 and 4.2-13 show 1044 GPM needed for each EDG. Table 4.2-1 lists flow for EDG HX.
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RAI-9 BACKGROUND The Strainer Outage cases listed in Tables 4.2-8 through 4.2-11 describe flow from two ERCW pumps through one strainer.
Request Is the flow rate and differential pressure across the single operable strainer within design specifications? In answering this question identify for strainer outage cases1 through 8 the flow rate through the single operable strainer, the differential pressure across the strainer and compare that to the maximum allowed flow rate and differential pressure for each strainer as specified by the manufacturer and/or other limiting design criteria.
RAI-1 0 BACKGROUND In Outage Cases 1 thru 4 the 6" ESF header crossties and the 16" Aux Building crossties are all open.
Request Please explain the purposes for having these crossties open when aligning for Outages 1 thru 4.
RAI-11 BACKGROUND Table 4.2-6 states for Outages 2 and 4, the accident unit's FCV-67-146 may have to be placed in the 35%
position in post recirculation in order to provide adequate flow to the Lower Containment Coolings (LCCs) to ensure Equipment Qualification (EQ) limits are not exceeded.
Request Please explain how the CCS is able to mitigate the MSLB in one unit and keep the other unit in Mode 5 when the accident unit's FCV-67-146 is in the 35% position as stated in Table 4.2-6. Do calculations support your response? Explain.
RAI-12 BACKGROUND Table 8 3/4.7-1 for 8 loop One Pump Operation requires isolating ERCW flow to the 18 Control Rod Drive Vent Cooler.
Request a)
Provide justification for isolating 1 B Control Rod Drive Vent Cooler, when Unit 1 is in Mode 1.
b)
Why is this necessary for the B Loop of unit 1 only and not the A loop for unit 1 nor either loop for unit 2?
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