ML18283A034

Supplement to Final Response to Generic Letter 2004-02, Dated August 13, 2018

ML18283A034
Person / Time
Site:	Calvert Cliffs
Issue date:	10/10/2018
From:	David Gudger Exelon Generation Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
GL 2004-002
Download: ML18283A034 (4)

Text

Exelon Generation ~

200 Exelon Way Kennett Square. PA 19348 www exeloncorp com 10 CFR 50.90 October 10, 2018 U.S. Nuclear Regulatory Commission ATIN: Document Control Desk Washington, DC 20555-0001 Calvert Cliffs Nuclear Power Plant, Units 1 and 2 Renewed Facility Operating License Nos. DPR-53 and DPR-69 Docket Nos. 50-317 and 50-318

Subject:

Supplement to Final Response to Generic Letter 2004-02, dated August 13, 2018.

References:

1. Final Response to Generic Letter 2004-02, dated August 13, 2018.

2. Calvert Cliffs Nuclear Power Plant, Units 1 and 2 - Supplemental Information Needed for Acceptance of Requested Licensing Actions RE:

Risk-Informed Approach to Closure for Generic Safety lssue-191 (EPID L-2018-LLA-0222 and EPID L-2018-LLE-0013, dated September 24, 2918.

By letter dated August 13, 2018, (Reference 1) Exelon Generation Company, LLC (Exelon) submitted its final response to Generic Letter (GL) 2004-02.

By letter dated September 24, 2018, (Reference 2) and followed by a clarification call on the same day, the Nuclear Regulatory Commission (NRC) transmitted a request for information needed to complete the NRC acceptance review of Reference 1.

Attachment 1 to this letter contains the requested information followed by Exelon's response.

There are no regulatory commitments contained in this letter.

I declare under penalty of perjury that the foregoing is true and correct. Executed on the 101h day of October 2018.

Supplement to Final Response to Generic Letter 2004-02 October 10, 2018 Page 2 If you should have any questions regarding this submittal, please contact Enrique Villar at 610-765-5736.

Respectfully, Jc,._._ ;_,) '- A-, cJ~

David T. Gudger Manager - Licensing & Regulatory Affairs Exelon Generation Company, LLC : Request for Supplemental Information cc: NRG Regional Administrator, Region I w/attachments NRG Senior Resident Inspector, CCNPP "

NRG Project Manager, NRA, CCNPP "

D. A. Tancabel, State of Maryland "

Request for Supplemental Information Final Response to Generic Letter 2004-02 License Amendment Request Docket Nos. 50-317 and 50-318 Page 1 of 2 Information Needed to Fully Describe Change

1. For in-vessel effects, provide a summary description of methodology for calculating the amount of fiber that transports to the reactor core.

2. Provide the following information to show that the in-vessel effects evaluation is consistent with or bounded by methods described in WCAP-16793-NP-A, Revision 2, "Evaluation of Long-Term Cooling Considering Particulate, Fibrous and Chemical Debris in the Recirculating Fluid," dated July 2013 (ADAMS Accession No. ML13239A114):

o Hot-leg break driving head available o ECCS flow rates o Types of fuel and inlet filters o How the fiber penetration amounts were determined o Cold-leg break fiber amount per fuel assembly.

Exelon's Response to Item 1 Scaled fiber bypass testing was performed by the strainer vendor using a prototypical fiber debris mix, and a nominal strainer flow rate. Two bypass tests were performed, and the results from the test having the higher amount of fiber bypass were used in subsequent calculations.

A similar test was performed by the same vendor for the Salem Nuclear Generating Station.

Following an extensive review of the Salem test, the NRC accepted the Salem response, which included an adjustment factor to be applied to the original fiber bypass test results.

Calvert Cliffs used the same evaluation approach as approved by the NRC for the Salem Station, and following discussions on July 2, 2014, Calvert Cliffs submitted their fiber bypass calculation for NRC review (ADAMS Accession No. ML15096A012).

In 2018 the Calvert Cliffs fiber bypass calculation was updated to reflect the latest input data from the risk informed approach. The calculation methodology itself is nearly the same as that used in the original version. The only notable difference is that during the computation of the fiber quantity predicted to bypass the test loop fiber bypass capture screen,) it is assumed that all fibers shorter than or equal to the largest capture screen dimension (0.44 mm) penetrate through the capture screen. This is different from the original version, which assumed all fibers shorter than or equal to 0.50 mm penetrate through the capture screen. While it is possible that some fibers longer than 0.44 mm may have passed through the fiber bypass capture screen this is offset by the fact that some fibers less than 0.44 mm will be filtered out on the fiber bypass capture screen.

After the strainer bypass test results are adjusted using the Salem methodology the resultant fiber bypass quantity is 14.4 grams per fuel assembly. The adjustment factor was also updated to be correlated to the total captured mass in the fiber bypass test.

Request for Supplemental Information Final Response to Generic Letter 2004-02 License Amendment Request Docket Nos. 50-317 and 50-318 Page 2 of 2 This result conservatively assumes that all fiber which passes through the sump strainer transports to the reactor fuel assemblies; i.e., no credit is taken for containment spray flow split reduction.

Exelon's Response to Item 2 Hot leg break driving head available:

The available hot-leg driving head at Calvert Cliffs is between 12.9 and 13.1 psi. The hot-leg break available driving head was calculated using the methodology in Section 10.3.2.3 of to LTR-SEE-1-10-23, Rev. 1, which is included as Appendix K to WCAP-16793-NP, Revision 2. The methodology is provided in response to RAI #18 in the PW ROG Response to Request for Additional Information Regarding Topical Report WCAP-16793-NP.

ECCS Flow rates:

The maximum flowrate per fuel assembly at Calvert Cliffs is 6.9 gpm. This flowrate is determined very conservatively assuming 1 LPSI pump fails to trip and is throttled to 600 gpm indicated, which with instrument uncertainty could be as high as 800 gpm, and the remaining HPSI pump flow rate of 620 gpm is increased to 700 gpm for a total injection flowrate of 1,500 gpm through 217 fuel assemblies. The maximum flowrate per fuel assembly for "normal" accident operation, which consists of 2 HPSI pumps injecting at a combined flow rate of 1,055 gpm, is 5.1 gpm.

Types of fuel and inlet filters:

The fuel used at Calvert Cliffs is Framatome (formerly AREVA) Advanced CE-14 HTP/HMP Fuel with FUELGUARD lower end fitting.

How the fiber penetration amounts were determined:

See response to Question 1.

Cold-leg break fiber amount per fuel assembly:

The maximum in-vessel fiber load is 14.4 grams per fuel assembly. This value is based on a hot leg break with cold leg recirculation. The grams of fiber per fuel assembly would be less for a cold leg break since some of the bypass fiber would spill out of the break before reaching the core.