ML17090A450

Revision to Technical Specification Bases - B 3.6.15

ML17090A450
Person / Time
Site:	Mcguire, McGuire
Issue date:	03/22/2017
From:	Duke Energy Corp
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
Download: ML17090A450 (5)

Text

Date: 3/22/2017 Distribution: Duke Energy Document Transmittal#: TR-NUC-MC-005612

1. Boyer, Robert P

2. Carroll, Michael E DOCUMENTTRANSMITTALFORM

Purpose:

~

3. Gardner, Troy R 1-------------------------1 Released By:

Facility: MCGUIRE NUCLEAR STATION Duke Eneray

4. Howell, Pamela T SUBJECT 13225 Haqers Ferry Road

5. Mc Ginnis, Vickie L Issue Tech Spec Bases - B 3.6.15 Document Management

6. OPS HUMAN PERFORMANCE -

MG02DM

7. OPS TRNG MGR.

Huntersville. NC 28078

8. QATS-MNSDCRM@duke-energy.com

9. RESIDENT NRC INSPECT

10. SERV BLDG FILE ROOM -

(})>u S-NUC REG WASHINGTON, DC

12. USNRC

13. WESTINGHOUSE ELECTRIC CO LLC Page 1of1 2 3 4 5 6 7 8 9 10 11 12 13 FYIIE FYIIE FYIIE FYIIE FYIIE R&AIE FYIIE PRINTILI FYIIE R&AIE R&AIE R&AIE Remarks:

Containment Recirculation Drains B 3.6.15 B 3.6 CONTAINMENT SYSTEMS B 3.6.15 Containment Recirculation Drains BASES

.BACKGROUND The containment recirculation drains consist of the ice condenser drains and the refueling canal drains. The ice condenser is partitioned into 24 bays, each having a pair of inlet doors that open from the bottom plenum to allow the hot steam-air mixture from a Design Basis Accident (OBA) to enter the ice condenser. Twenty of the 24 bays have an ice condenser floor drain at the bottom to drain the melted ice into the lower compartment (in the 4 bays that do not have drains, the water drains through the floor drains in the adjacent bays). Each drain leads to a drain pipe that drops down several feet, then makes one or more 90° bends and exits into the lower compartment. A check (flapper) valve at the end of each pipe keeps warm air from entering during normal operation, but when the water exerts pressure, it opens to allow the water to spill into the lower compartment. This prevents water from backing up and interfering with the ice condenser inlet doors. The water delivered to the lower containment serves to cool the atmosphere as it falls through to the floor and provides a source of borated water at the containment sump for long term use by the Emergency Core Cooling System (ECCS) and the Containment Spray System during the recirculation mode of operation.

The six refueling canal drains are positioned in ttie bottom and sides of the refueling canal. During a refueling, valves are closed in the side drains and a blind flange is installed in the bottom drain and the canal is flooded to facilitate the refueling process. The water acts to shield and cool the spent fuel as it is transferred from the reactor vessel to storage.

After refueling, the canal is drained and the valves in the side drains are locked open and the blind flange in the bottom drain is removed. In the event of a OBA, the refueling canal drains are the main return path to the lower compartment for Containment Spray System water sprayed into the upper compartment.

The ice condenser drains and the refueling canal drains function with the ice bed, the Containment Spray System, and the ECCS to limit the

• pressure and temperature that could be expected following a OBA.

APPLICABLE The limiting DBAs considered relative to containment temperature and SAFETY ANALYSES pressure are the loss of coolant accident (LOCA) and the steam line break (SLB). The LOCA and SLB are analyzed using computer codes designed to predict the resultant containment pressure and temperature transients. DBAs are assumed not to occur simultaneously or consecutively. Although the ice condenser is a passive system that McGuire Units 1 and 2 B 3.6.15-1 Revision No. 147

Containment Recirculation Drains B 3.6.15 BASES APPLICABLE SAFETY ANALYSES (continued) requires no electrical power to perform its function, the Containment Spray System and the Air Return System (ARS) also function to assist the ice bed in limiting pressures and temperatures. Therefore, the analysis of the postulated DBAs, with respect to Engineered Safety Feature (ESF) systems, assumes the loss of one ESF bus, which is the worst case single active failure and results in one train of the Containment Spray System and one train of the ARS being rendered inoperable.

The limiting OBA analyses (Ref. 1) show that the maximum peak containment pressure results from the LOCA analysis and is calculated to be less than the containment design pressure. The maximum peak containment atmosphere temperature results from the SLB analysis and is discussed in the Bases for LCO 3.6.5, "Containment Air Temperature."

In addition to calculating the overall peak containment pressures, the OBA analyses include calculation of the transient differential pressures that occur across subcompartment walls during the initial blowdown phase of the accident transient. The internal containment walls and structures are designed to withstand these local transient pressure differentials for the limiting DBAs.

The containment recirculation drains satisfy Criterion 3 of 10 CFR 50.36 (Ref. 2).

LCO This LCO establishes the minimum requirements to ensure that the containment recirculation drains perform their safety functions. The ice condenser floor drain valve disks must be closed to minimize air leakage into and out of the ice condenser during normal operation and must open in the event of a OBA when water begins to drain out. The refueling canal drain valves in the side drains must be locked open and the blind flange in the bottom drain must be removed and remain clear to ensure the return of Containment Spray System water to the lower containment in the event of a OBA. The containment recirculation drains function with the ice condenser, ECCS, and Containment Spray System to limit the pressure and temperature that could be expected following a OBA.

APPLICABILITY In MODES 1, 2, 3, and 4, a OBA could cause an increase in containment pressure and temperature, which would require the operation of the containment recirculation drains. Therefore, the LCO is applicable in MODES 1, 2, 3, and 4.

The probability and consequences of these events in MODES 5 and 6 are low due to the pressure and temperature limitations of these MODES.

McGuire Units 1 and 2 B 3.6.15-2 Revision No. 147

Containment Recirculation Drains B 3.6.15 BASES APPLICABILITY (continued)

As such, the containment recirculation drains are not required to be OPERABLE in these MODES.

ACTIONS If one ice condenser floor drain is inoperable, 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> is allowed to restore the drain to OPERABLE status. The Required Action is necessary to return operation to within the bounds of the containment analysis. The 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> Completion Time is consistent with the ACTIONS of LCO 3.6.1, "Containment," which requires that containment be restored to OPERABLE status within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />.

• If one refueling canal drain is inoperable, 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> is allowed to restore the drain to OPERABLE status. The Required Action is necessary to return operation to within the bounds of the containment analysis. The 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> Completion Time is consistent with the ACTIONS of LCO 3.6.1, which requires that containment be restored to OPERABLE status in 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />.

C.1 and C.2 If the affected drain(s) cannot be restored to OPERABLE status within the required Completion Time, the plant must be brought to a MODE in which the LCO does not apply. To achieve this status, the plant must be brought to at least MODE 3 within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and to MODE 5 within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />. The allowed Completion Times are reasonable, based on operating experience, to reach the required plant conditions from full power conditions in an orderly manner and without challenging plant systems.

SURVEILLANCE SR 3.6.15.1 and SR 3.6.15:2 REQUIREMENTS Verifying the OPERABILITY of the refueling canal drains ensures that they will be able to perform their functions in the event of a OBA. SR 3.6.15.1 confirms that the refueling canal drain valves in the side drains have been locked open and the blind flange in the bottom drain has been removed and that the drains are clear of any obstructions that could impair their functioning. In addition to debris near the drains, SR 3.6.15.2 requires attention be given to any debris that is located where it could be McGuire Units 1 and 2 B 3.6.15:.3 Revision No. 147

Containment Recirculation Drains B 3.6.15 BASES SURVEILLANCE REQUIREMENTS (continued) moved to the drains in the event that the Containment Spray System is in operation and water is flowing to the drains. SR 3.6.15.1 must be performed before entering MODE 4 from MODE 5 after every filling of the canal to ensure that the valves in the side drains have been locked open and the blind flange in the bottom drain has been removed and that no debris that could impair the drains was deposited during the time the canal was filled. The Surveillance Frequency is based on operating experience, equipment reliability, and plant risk and is controlled under the Surveillance Frequency Control Program.

SR 3.6.15.3 Verifying the OPERABILITY of the ice condenser floor drains ensures that they will be able to perform their functions in the event of a OBA.

Inspecting the drain valve disk ensures that the valve is performing its function of sealing the drain line from warm air leakage into the ice condenser during normal operation, yet will open if melted ice fills the line following a OBA. Verifying that the drain lines are not obstructed ensures their readiness to drain water from the ice condenser. The Surveillance Frequency is based on operating experience, equipment reliability, and plant risk and is controlled under the Surveillance Frequency Control Program.

REFERENCES 1. UFSAR, Section 6.2.

2. 10 CFR 50.36, Technical Specifications, (c)(2)(ii).

McGuire Units 1 and 2 B 3.6.15-4 Revision No. 147