L-16-018, Report of Information That Significantly Improves Accuracy of Rtpts Value

Report of Information That Significantly Improves Accuracy of Rtpts Value

ML16265A047
Person / Time
Site:	Beaver Valley
Issue date:	09/20/2016
From:	Richey M FirstEnergy Corp
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
L-16-018
Download: ML16265A047 (3)

Text

FENOC' Beaver Valley Power Station P.O. Box 4 Shippingporl, PA 15077 FirstEnergy Nuclear Operating Company Marty L. Richey 724-682-5234 Site Vice President Fax: 724-643-8069 September 20, 2016 L-16-018 10 CFR 50.61(c)(3)

ATTN: Document Control Desk U. S. Nuclear Regulatory Commission Washington, DC 20555-0001

SUBJECT:

Beaver Valley Power Station, Unit No. 1 Docket No. 50-334, License No. DPR-66 Report of Information That Significantly Improves Accuracy of RTPTS Value Pursuant to 10 CFR 50.61(c)(3), FirstEnergy Nuclear Operating Company (FENOC) is hereby reporting information that significantly improves the accuracy of the pressurized thermal shock reference temperature (RTPTs) for Beaver Valley Power Station, Unit No. 1 (BVPS-1). As a result of a more accurate evaluation, the value for the initial (unirradiated) nil ductility reference temperature for the limiting reactor vessel material (RTNDT(UJ) improved, as described below. The accuracy of RTPTS is expected to improve when re-calculated using the revised value for RTNDT(U).

On July 30, 2013, FENOC submitted a license amendment request to implement 10 CFR 50.61a "Alternate fracture toughness requirements for protection against pressurized thermal shock events" (ADAMS Accession No. ML13212A027). A December 11, 2014 Nuclear Regulatory Commission (NRG) staff letter (ADAMS Accession No. ML14218A762) requested FENOC to: "Identify the specific methodology in MTEB 5-2 and provide the calculations used to determine RT NDT(U) for each of the plate materials in Table 3.3-1."

Consistent with the standard practice when the RT NDT(U) values were originally determined, a hand-drawn curve was graphed through the minimum Charpy V-notch test data points in accordance with American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code) Section Ill, "Rules for the Construction of Nuclear Power Plant Components," Subarticle NB-2331, Paragraph (a)(4). While re evaluating the RTNDT(U) of the reactor vessel in response to the NRG staff request, the original material test data was graphed using computer code CVGRAPH, Version 6.0, with a symmetric hyperbolic tangent curve fit through the minimum data points in accordance with ASME Code Section Ill, Subarticle NB-2331, Paragraph (a)(4).

Beaver Valley Power Station, Unit No. 1 L-16-018 Page 2 Use of the symmetric hyperbolic tangent curve fit is considered to be appropriate because it follows the current industry practice for fitting surveillance capsule Charpy V-notch test data. The symmetric hyperbolic tangent curve fit is used in the credibility assessment and to determine the measured upper-shelf energy decrease and 30 foot pound shift values of the surveillance capsule material. Additionally, the current embrittlement correlations that are used for various reactor vessel integrity calculations contained in Regulatory Guide 1.99, "Radiation Embrittlement of Reactor Vessel Materials," Revision 2, and the Pressurized Thermal Shock (PTS) Rule (10 CFR 50. 61, "Fracture toughness requirements for protection against pressurized thermal shock events"), were based on a symmetric hyperbolic tangent curve fit to the data. Therefore, use of the symmetric hyperbolic tangent curve fit for the RTNDT{U) determination is consistent with the current industry practice regarding reactor vessel integrity Charpy V-notch test data applications.

The initial RT NDT(U) values for the BVPS-1 reactor vessel materials improved as a result of fitting the original material test data with the hyperbolic tangent curve instead of the hand-drawn curve. Table 1 identifies the RTNDT(U) values that were determined using the hand-drawn curve fit and the hyperbolic tangent curve fit through the minimum data points. In order to verify the re-evaluated RTNDT(U) values, an industry consultant was contracted to perform an independent verification of the results. Using the symmetric hyperbolic tangent curve fitting computer code, the consultant determined the same results as shown in Table 1.

Table 1 Comparison of RT NDT(U) Values for BVPS-1 Beltline Plate Materials Using Hand-Drawn and Hyperbolic Tangent Curve Fits Hand Drawn Curve Fit Hyperbolic Tangent Curve Fit Reactor Vessel 8eltline Material RTNDT(U) RTNDT(U)

(oF) (oF)

Intermediate Shell Plate 86607-1 43 26.8 Intermediate Shell Plate 86607-2 73 53.6 Lower Shell Plate 87203-2 20 0.4 Lower Shell Plate 86903-1 27 13.1 Because RTNDT{U) is an input into the calculation for RTPTs, it is expected that the accuracy of RTPTs will improve and the value of RTPTS will be reduced when re calculated using the revised value for RT NDT(U). Based on the expected reduction in the RTPTS value, the July 30, 2013 license amendment request to authorize implementation of the alternate PTS rule (that is, 10 CFR 50.61a) was not expected to be needed.

Therefore, FENOC withdrew the July 30, 2013 license amendment request by letter dated February 5, 2015 (ADAMS Accession No. ML15036A424).

Beaver Valley Power Station, Unit No. 1 L-16-018 Page 3 FENOC intends to use the revised RTNDT(U) values as input to the next revision of the pressure-temperature limit curves for BVPS-1, which are scheduled to be implemented prior to July 2017.

There are no regulatory commitments contained in this submittal. If there are any questions or if additional information is required, please contact Mr. Thomas A. Lentz, Manager- Fleet Licensing, at 330-315-6810.

Sincerely,

)e.p Marty L. \ hey cc: NRC Region I Administrator NRC Resident Inspector NRC Project Manager Director BRP/DEP Site BRP/DEP Representative