ML15065A030
| ML15065A030 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 03/03/2015 |
| From: | George Gellrich Exelon Generation Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| TAC MF3388, TAC MF3389 | |
| Download: ML15065A030 (8) | |
Text
A ExeLon Generation.
George Gellrich Site Vice President Calvert Cliffs Nuclear Power Plant 1650 Calvert Cliffs Parkway Lusby, MD 20657 410 495 5200 Office 717 497 3463 Mobile www.exeloncorp.com george.gellrich@exeloncorp.com 10 CFR 50.59 March 3, 2015 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555 Calvert Cliffs Nuclear Power Plant, Unit Nos. 1 and 2 Renewed Facility Operating License Nos. DPR-53 and DPR-69 NRC Docket Nos. 50-317 and 50-318
Subject:
References:
Request for Additional Information Regarding Atmospheric Dump Valves License Amendment Request
- 1.
Letter from G. H. Gellrich (Exelon) to Document Control Desk (NRC), dated January 13,
- 2014, License Amendment Request:
Add Technical Specification for Atmospheric Dump Valves
- 2.
Letter from N. S. Morgan (NRC) to G. H. Gellrich (Exelon), dated February 2, 2015, Calvert Cliffs Nuclear Power Plant, Unit Nos. 1 and 2 - Request for Additional Information Regarding Atmospheric Dump Valves License Amendment Request (TAC Nos. MF3388 and MF3389)
Reference 1 submitted a license amendment request to add a Technical Specification for the Atmospheric Dump Valves. As part of their review, the NRC staff has requested additional information (Reference 2). Responses to the requested additional information are provided in Attachment (1).
This additional information does not change the No Significant Hazards Determination provided in Reference 1. No regulatory commitments are contained in this letter.
Should you have questions regarding this matter, please contact Mr. Michael J. Fick at (410) 495-6714.
Document Control Desk March 3, 2015 Page 2 I declare under penalty of perjury that the foregoing is true and correct. Executed on March 3, 2015.
Respectfully, George H. Gellrich Site Vice President GHG/PSF/bjm I
I
Attachment:
(1)
Request for Additional Information Regarding Atmospheric Dump Valves
Enclosure:
1 Proposed Technical Specification Bases Changes cc:
NRC Project Manager, Calvert Cliffs NRC Resident Inspector, Calvert Cliffs NRC Regional Administrator, Region I S. Gray, MD-DNR
ATTACHMENT (1)
REQUEST FOR ADDITIONAL INFORMATION REGARDING ATMOSPHERIC DUMP VALVES Calvert Cliffs Nuclear Power Plant March 3, 2015
ATTACHMENT (1)
REQUEST FOR ADDITIONAL INFORMATION REGARDING ATMOSPHERIC DUMP VALVES By letter dated January 13, 2014 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML14015A138), as supplemented by letter dated November 3, 2014 (ADAMS Accession No. ML14309A717), Calvert Cliffs Nuclear Power Plant, LLC, the licensee, submitted a license amendment request to add Technical Specification (TS) 3.7.18, "Atmospheric Dump Valves (ADVs)," for Calvert Cliffs Nuclear Power Plant, Unit Nos. 1 and 2.
By letter dated November 3, 2014, the licensee provided responses to the Nuclear Regulatory Commission (NRC) staffs request for additional information (RAI) dated September 17, 2014 (ADAMS Accession No. ML 14237A,069). In order to complete its review, the NRC staff needs the following additional information:
BALANCE OF PLANT (BOP) RAI-9%
In parts a. 1 and a.2 of its response to RAI BOP-1, the licensee stated:
A drawing of the ADV valve body has been attached for reference (Enclosure 1) [Drawings of the ADV Valve Body, Operator]. The ADV stem travels in the downward direction, into the steam space to open the valve. The valve is equipped with a pilot to assist in initial opening.
A drawing of the ADV valve operator has been attached for reference (Enclosure 1).
The ADV is an air-to-open, fail closed, valve. Air is applied to the top of the valve diaphragm in order to lower the valve stem, and open the valve.
Air acts against the large spring (item #31), compressing it, in order to open the valve. With no air on the diaphragm, the spring forces the valve shut.
A manual operator is provided with the valve. The operator forces a rod into the valve that will act to compress the spring. The manual operator does not function to close the valve.
The manual operator can be inserted to open the valve, or removed to allow the valve to close.
Remote operation is the preferred method of operation; however, it is not credited in the accident analyses to mitigate the consequences of the event.
a.2 Local (manual handwheel) operation of the valve is credited to mitigate the consequences of some events. As described in the Updated Final Safety Analysis Report (UFSAR), Section 14.15, Steam Generator Tube Rupture, this event is the most limiting event for ADV operation. In this event, the ADV does not have to be operated for up to two hours following initiation of the event. Again, remote operation is preferred, but not required.
The NRC staff requests that the licensee provide a discussion of how the ADV manual operator with chain operator (and associated valve extension components) is designed to withstand a design bases event, including a seismic event. Also describe the safety classification of the ADV valve operator with chain operator, including such components as the reach rod linkage, gear box, shaft, and associated linkage and gear box supports.
The handwheel assembly consists of a gear box, a handwheel with chains, shafts, supports, and associated linkage. The assembly is located externally, on the top of the ADV enclosure. A short portion of the linkage projects down through the top cover plate of the enclosure. The ADV enclosure is located in the Auxiliary Building and is therefore protected from external events, such as tornados and hurricanes.
It is not located in an area subject to accident environmental condition extremes of temperature or radiation for the accidents of concern. It remains accessible to operators post-accident.
1
ATTACHMENT (1)
REQUEST FOR ADDITIONAL INFORMATION REGARDING ATMOSPHERIC DUMP VALVES The handwheel assembly is installed to satisfy AQ-11/1 seismic requirements. The handwheel assemblies are of rugged construction and mounted on plate steel stanchions, which are welded to the ADV enclosures. We are evaluating the need to upgrade the seismic adequacy of the handwheel assembly consistent with its function.
BOP RAI-10:
In part a. 6 of its response to RAI BOP-1, the licensee stated:
The Completion Times were chosen to be consistent with the Completion Times in Millstone Unit 2 TS. Millstone Unit 2 is a Combustion Engineering plant with only one ADV per SG
[steam generator]. Additionally, the Millstone Unit 2 TSs do not include the block valves in the TSs, even though we believe their design is virtually identical to ours.
The NRC staff requests the licensee to justify why there is not a TS surveillance for the ADV line by local manual operation, similar to the Millstone Unit 2 TS Surveillance Requirement (SR) 4.7.1.7. For example, the Millstone TS SR states to verify each atmospheric dump line by local manual operation. The proposed Calvert Cliff's TS SR 3.7.18.1 states to verify one complete cycle of each ADV. The actual accident function of the ADV is with the local manual operation via the ADV reach rod and chain operator.
The cycling of the ADV, currently performed each refueling outage, is done manually using the handwheel. The intent of the Technical Specification Surveillance Requirement proposed was to continue to perform the same local manual test to ensure that the safety function of the valve is tested.
The proposed Technical Specification Bases have been updated to clarify this information. This Bases replaces the Technical Specification Bases in the January 13, 2014 (ML14015A138) letter. The updated Technical Specification Bases are in Enclosure 1.
2
ENCLOSURE1 PROPOSED TECHNICAL SPECIFICATION BASES PAGES Calvert Cliffs Nuclear Power Plant March 3, 2015
ENCLOSURE 1 PROPOSED TECHNICAL SPECIFICATION BASES PAGES B3.7.18 Atmospheric Dump Valves (ADVs)
Background
The ADVs provide a safety grade method for cooling the unit to Shutdown Cooling (SDC)
System entry conditions, should the preferred heat sink via the Turbine Bypass Valves to the condenser not be available, as discussed in the UFSAR, Section 10.3 (Reference 1). This is done in conjunction with the Auxiliary Feedwater System providing cooling water from the condensate storage tank (CST). The ADVs may also be used during a normal cooldown when steam pressure drops too low for maintenance of a vacuum in the condenser to permit use of the Turbine Bypass Valves.
Two ADV lines are provided, one per steam generator. Each ADV line consists of one ADV and an associated isolation valve. The ADVs are provided with upstream isolation valves to permit their being tested at power, if desired. The ADVs are equipped with manual hand wheels to open and close them. Pneumatic controllers are used to operate the ADVs as the preferred method, but are not relied upon during an accident.
A description of the ADVs is found in Reference 1. The ADVs are considered OPERABLE when the manual control is available for local manual operation.
Applicable Safety Analyses The design basis of the ADVs is established by the capability to cool the unit to SDC System entry conditions. The cooldown rate assumed in the accident analyses is obtainable by one or both steam generators. The design is adequate to cool the unit to SDC System entry conditions with only one ADV and one steam generator.
In the steam generator tube rupture accident analysis presented in the UFSAR, the ADVs are assumed to be used by the operator to cool down the unit to SDC System entry conditions because the accident is accompanied by a loss of offsite power. Prior to the operator action, the MSSVs are used to maintain steam generator pressure and temperature at the MSSV setpoint. The ADVs may be used for other accidents that are accompanied by a loss of offsite power. The limiting events are those that render one steam generator unavailable for RCS heat removal, with a coincident loss of offsite power. Typical initiating events falling into this category are a feedwater line break, and a SGTR event (limiting case).
The ADVs satisfy Criterion 3 of 10 CFR 50.36(c)(2)(ii).
LCO Two ADV lines are required to be OPERABLE to ensure that at least one ADV is OPERABLE to conduct a unit cooldown following an event in which one steam generator becomes unavailable.
A closed isolation valve does not render its ADV line inoperable since operator action time to open the isolation valve is supported in the accident analysis.
Failure to meet the LCO can result in the inability to cool the unit to SDC System entry conditions following an event in which the condenser is unavailable for use with the Turbine Bypass Valves. An ADV is considered OPERABLE when it is capable of providing relief of the main steam flow, and is capable of fully opening and closing when required.
1
ENCLOSURE 1 PROPOSED TECHNICAL SPECIFICATION BASES PAGES Applicability In MODES 1, 2, and 3, and in MODE 4, when steam generators are being relied upon for heat removal, the ADVs are required to be OPERABLE.
In MODES 5 and 6, an SGTR is not a credible event.
Actions A.1 With one required ADV line inoperable, action must be taken to restore the OPERABLE status within 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />. The 48 hour5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> Completion Time takes into account the redundant capability afforded by the remaining OPERABLE ADV line, and a Packup in the Turbine Bypass Valves and MSSVs.
B.1 With two required ADV lines inoperable, action must be taken to restore one of the ADV lines to OPERABLE status. As the isolation valve can be closed to isolate an ADV, some repairs may be possible with the unit at power.
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 reasonable to repair inoperable ADV lines, based on the availability of the Turbine Bypass Valves and MSSVs, and the low probability of an event occurring during this period that requires the ADV lines.
C.1 and C.2 If the ADV lines cannot be restored to OPERABLE status within the associated Completion Time, the unit must be placed in a MODE in which the LCO does not apply. To achieve this status, the unit must be placed in 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 in MODE 4, without reliance upon the steam generator for heat removal, within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. The allowed Completion Times are reasonable, based on operating experience, to reach the required unit conditions from full power conditions in an orderly manner and without challenging unit systems.
Surveillance Requirements SR 3.7.18.1 To perform a cooldown of the RCS, the ADVs must be able to be opened through their full range. This SR ensures the ADVs are tested through a full cycle at least once per fuel cycle.
This test is performed using the manual handwheel assembly. Porformanco of ineorv,,i t..ting er-Any use of an ADV during a '-a-nit -edewn using the manual handwheel assembly may satisfy this requirement. Operating experience has shown that these components usually pass the SR when performed at the 24 month Frequency. Therefore, the Frequency is acceptable from a reliability standpoint.
References
- 1. UFSAR, Section 10.3 2