ML15090A192

Calvert Cliffs, Units 1 and 2, Supplemental Information - Atmospheric Dump Valves License Amendment Request

ML15090A192
Person / Time
Site:	Calvert Cliffs
Issue date:	03/27/2015
From:	Gellrich G H Exelon Generation Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
Download: ML15090A192 (5)

Text

A Exeton Generation.George GellrichSite Vice PresidentCalvert Cliffs Nuclear Power Plant1650 Calvert Cliffs ParkwayLusby, MD 20657410 495 5200 Office717 497 3463 Mobilewww.exeloncorp.comgeorge.gellrich@exeloncorp.com10 CFR 50.90March 27, 2015U. S. Nuclear Regulatory CommissionATTN: Document Control DeskWashington, DC 20555Calvert Cliffs Nuclear Power Plant, Unit Nos. 1 and 2Renewed Facility Operating License Nos. DPR-53 and DPR-69NRC Docket Nos. 50-317 and 50-318

References:

Supplemental Information -Atmospheric Dump Valves License AmendmentRequest1. Letter from G. H. Gellrich (Exelon) to Document Control Desk (NRC), datedJanuary 13, 2014, License Amendment Request: Add TechnicalSpecification for Atmospheric Dump Valves2. Letter from G. H. Gellrich (Exelon) to Document Control Desk (NRC), datedMarch 3, 2015, Request for Additional Information Regarding AtmosphericDump Valves License Amendment RequestReference 1 submitted a license amendment request to add a Technical Specification for theAtmospheric Dump Valves. As part of their review, the NRC staff has requested additionalinformation and responses to the requested additional information were provided inReference 2. During a subsequent phone call with the NRC staff on March 17, 2015, it wasidentified that supplemental information was needed to clarify the response provided inReference 2. The requested information is in Attachment (1).This additional information does not change the No Significant Hazards Determination providedin 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.AQ~

Document Control DeskMarch 27, 2015Page 2I declare under penalty of perjury that the foregoing is true and correct. Executed on March 27,2015.Respectfully,George H. GellrichSite Vice PresidentGHG/PSF/bjm

Attachment:

(1) Supplemental Informationcc: NRC Project Manager, Calvert CliffsNRC Regional Administrator, Region INRC Resident Inspector, Calvert CliffsS. Gray, MD-DNR ATTACHMENT (1)SUPPLEMENTAL INFORMATIONCalvert Cliffs Nuclear Power PlantMarch 27, 2015 ATTACHMENT 1SUPPLEMENTAL INFORMATIONDuring a phone call with the NRC Staff on March 17, 2015, clarifying information was providedto address how the atmospheric dump valve (ADV) manual operator is designed to withstand adesign basis event, including a seismic event.GDC-2As stated in our Final Safety Analysis Report submittal (1971) the plant design and constructionproceeded based upon the intent of the draft General Design Criteria (GDC). General DesignCriteria-2 (1967 draft) states, "Those systems and components of reactor facilities which areessential to the prevention of accidents which could affect the public health and safety or tomitigation of their consequences shall be designed, fabricated, and erected to performancestandards that will enable the facility to withstand, without loss of the capability to protect thepublic, the additional forces that might be imposed by natural phenomena such as earthquakes,tornados, flooding conditions, winds, ice, and other local site effects. The design bases soestablished shall reflect: (a) appropriate consideration of the most severe of these naturalphenomena that have been recorded for the site and the surrounding area and (b) anappropriate margin for withstanding forces greater than those recorded to reflect uncertaintiesabout the historical data and their suitability as a basis for design."Unlike the current GDC-2, the draft GDC did not require consideration of appropriatecombinations of the effects of normal and accident conditions with the effects of the naturalphenomena. Therefore, a number of systems, including the ADVs, were not designed for acombination of accident loads with natural phenomenon. The safety function of the ADVs is torespond to a Steam Generator Tube Rupture event; a seismic event is not consideredconcurrently with a Steam Generator Tube Rupture event.Seismic Il/IThe issue of seismic qualification of mechanical and electrical equipment was designated asUnresolved Safety Issue (USI) A-46 in December 1980. The safety concern was thatequipment in nuclear power plants with construction permit applications docketed before 1972was not reviewed according to current licensing criteria. The NRC Staff determined that it wasnot feasible to require older operating plants to meet current licensing requirements(NUREG-1211). Therefore, a number of alternative processes were investigated. The processchosen used seismic experience data to evaluate the seismic capability of equipment. Thisalternative provided the most reasonable and cost effective means to ensure that the intent ofGDC-2 is met. To implement this resolution to USI A-46, the NRC issued GL 87-02.Supplement 1 to GL 87-02 approved the industry's methodology and criteria for evaluatingequipment.This methodology was used to evaluate the Calvert Cliffs ADVs and their enclosures in the1990's. The methodology included addressing potential adverse seismic interactions(seismic Il/I concerns).Recently, the chain wheel and in-line gear assembly supports on top of the ADV enclosureswere once again evaluated as part of a replacement effort. Since the equipment is located inthe Auxiliary Building, in the vicinity of SR-CATI equipment, these components are required tobe supported in accordance with seismic li/I criteria (i.e., no damage to safety-relatedcomponents from this equipment shall occur during or after a safe shutdown earthquake). Theevaluation was performed to compare the original components to the new components todetermine that they continue to meet seismic Il/I criteria.1 ATTACHMENT 1SUPPLEMENTAL INFORMATIONDepending on which unit they are installed, the chain wheel and in-line gear assembly supportsconsist of either stiffened, welded steel plate mounting brackets, or W4xl 3 steel sections, withwelded adaptor plates. Both of these configurations are welded directly to the top of theirrespective ADV enclosure.By observation of the structural robustness of the welded supports it was determined that thenew replacement chain wheel and in-line gear assemblies, subjected to design basis seismicdemand accelerations, will not adversely impact the structural integrity of their supports, theADV enclosures, or nearby Category I equipment. The support brackets are sufficientlystiffened and welded to preclude them from developing significant bending or shear stresses.The chain wheel and in-line gear assembly supports are acceptable.Maintenance RuleThe ADVs and the manual operator have a maintenance rule function and are included in theMaintenance Rule program. Specifically, the Maintenance Rule function for the ADV manualoperator is, "Manual Operators for ADVs operate to depressurize the affected SteamGenerator." One functional failure is allowed per 24 month period.2