L-14-198, Report of Changes and Errors Pursuant to 10 CFR 50.46

Report of Changes and Errors Pursuant to 10 CFR 50.46

ML14170A178
Person / Time
Site:	Perry
Issue date:	06/18/2014
From:	Harkness E FirstEnergy Nuclear Operating Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
L-14-198
Download: ML14170A178 (5)

Text

FENOC' Perry Nuclear Power Plant P.O. Box 97 10 Center Road RrstEnergy Nuclear Operating Company Perry. Ohio 44081 Ernest J. HBrf<ness 440-280-5382 Vice President Fax: 440-280-8Q29 June 18, 2014 L-14-198 10 CFR 50.46 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555-0001

SUBJECT:

Perry Nuclear Power Plant Docket No. 50-440, License No. NPF-58 Report of Changes Pursuant to 10 CFR 50.46 On May 23, 2014, Global Nuclear Fuel -Americas, LLC (GNF) issued a change and three errors in the evaluation model regarding the emergency core cooling system (ECCS) - loss of coolant accident (LOCA) methodology used for the Perry Nuclear Power Plant (PNPP). Pursuant to 10 CFR 50.46, "Acceptance Criteria for Emergency Core Cooling Systems (ECCS) for Light-Water Nuclear Power Reactors," FirstEnergy Nuclear Operating Company (FENOC) is notifying the Nuclear Regulatory Commission (NRC) of the change and errors.

The change notification reflects a change to a new version of SAFER04A, release (E4).

The changes as compared to earlier versions of SAFER are regarded as code maintenance items. Minimal influence is seen on the hot node heat-up calculation, and sensitivity calculations have demonstrated that these items individually and collectively have an insignificant effect on calculated peak cladding temperature (PCT). The PCT change for PNPP as a result is 0 degrees Fahrenheit (°F).

The first error notification corrects a logic error occurring with an indication that the expected system mass diverges from the calculated actual system mass. This occurs when upper plenum liquid mass and core spray flow rate is low, and system mass is gradually lost due to core spray being discarded, resulting in marginally less ECCS flow credited as reaching the core. The PCT change for PNPP as a result of this notification is 0°F.

Perry Nuclear Power Plant L-14-198 Page2 The second error is due to calculation of a non-physically low delta pressure (Ap) for droplet flow above a two-phase level in the core where an earlier version of the model imposed a minimum core Ap. It has been observed that for cores with greater voiding (more steam flow), this minimum Ap could be non-conservative, actually driving the steam flow slightly, and offering inappropriate steam cooling benefit above the core two-phase level. The code is changed to remove the imposition of the minimum core Ap, and an explicit core Ap calculation is applied, without regard to droplet condition, via input in the standard model. The error principally affects design basis accident (OBA) large break cases. Small break limited plants, with liquid inventory remaining In the core, are less affected by droplet behavior and steam cooling, and shows no change to a slight benefit by the adjusted core Ap calculation. The PCT change for PNPP as a result of this notification is a decrease of 15°F.

The third error involves the application of a counter current flow limitation (CCFL) on the interface between the hot bundle and the lower plenum. The pressure head applied at that location is based on the liquid water level in the bundle. It was found, upon exercising the routine to define CCFL, the output would replace the pressure head with a value revised by that calculation, resulting in a representation of pressure head slightly different from that of the calculated water level in the bundle. The iteration scheme for CCFL has been fixed in the SAFER04A E4 model so that, consistently, the level head is applied whenever CCFL is calculated in that location. A more consistent pressure head from the hot bundle water level as input to the CCFL routine results in slightly better indicated performance in overcoming CCFL at the interface between the hot bundle and the lower plenum. The effect demonstrated by representative sensitivity studies has shown this correction to be a small penalty for small break limited plants, and a general benefit (no change to some reduction of PCT) for plants with large break limited analyses. The PCT change for PNPP as a result of this notification is 0°F.

The attachment contains a summary of the 1O CFR 50.46 changes and errors, including the most recent change and errors, applicable to the GE14 fuel in use at PNPP. The summation of the absolute values of these changes and errors results in a value that meets the definition of a significant change as defined by 10 CFR 50.46(a)(3)(i).

Therefore, pursuant to 1O CFR 50.46(a)(3)(ii), NRC notification of the recent change and errors is required within 30 days.

As a result of incorporating the change and errors along with previously reported changes and errors, the PNPP PCT is now 1555°F (was 1570°F) and continues to satisfy the 10 CFR 50.46(b)(1) criteria of PCT not to exceed 2200°F.

Perry Nuclear Power Plant L-14-198 Page 3 The impact on the ECCS evaluation model does not result in any challenge to the 10 CFR 50.46(b) acceptance criteria. The change and errors have been evaluated, and

. there are no other known errors or changes to be evaluated at this time. The overall evaluation model is considered acceptable; therefore, a reanalysis is not required.

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

s:;;~

Ernest J. Harkness

Attachment:

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Perry Nuclear Power Plant 10 CFR 50.46 Changes and Errors cc: NRC Region Ill Administrator NRC Resident Inspector NRC Project Manager

Attachment L-14-198 Perry Nuclear Power Plant 10 CFR 50.46 Changes and Errors Page 1of2 Vendor Summary of Change/Error Licensing Basis Peak Licensee Report of Notification Clad Temperature (PCT) Notification Number Impact (Accession No.)

2001-02 Impact of SAFER1 pressure PCT impact for GE14 ML020710641 rate Inconsistency error. fuel is +5 degree Fahrenheit C~F).

2002-01 Impact of SAFER core spray PCT impact for GE14 ML030710170 injection elevation error. fuel Is +15°F.

2002-02 Impact of SAFER bulk water PCT impact for GE14 ML030710170 level error. fuel Is 0°F.

2002-04 Impact of SAFER04 PCT impact for GE14 ML030710170 computer platform change. fuel is 0°F 2002-05 Impact of error in WEVOL2 PCT impact for GE14 ML030710170 calculation of downcomer free fuel is 0°F.

volume.

2003-01 Impact of SAFER level/ PCT impact for GE14 ML040710502 volume table error. fuel is +5°F.

2003-03 Impact of SAFER initial steam PCT impact for GE14 ML040710502 separator pressure drop fuel is 0°F.

error.

2003-05 Impact of postulated PCT Impact for GE14 ML040710502 post-LOCA3 hydrogen-oxygen fuel is 0°F.

recombination.

2006-01 Impact of top peaked power PCT impact for GE14 ML062490520 shape for small break LOCA fuel Is 0°F. ML070390113 analysis.

2011-02 Impact of database error for PCT impact for GE14 ML112290919 heat deposition for fuel Is +25°F.

1OX10 fuel bundles.

2011-03 Impact of updated formulation PCT impact for GE14 ML112290919 gamma heat deposition to fuel is -40°F.

channel wall for 1OX10 fuel bundles.

2012-01 Impact of change in fuel PCT impact for GE14 ML12353A320 properties from GESTR fuel is +20°F.

to PRIME

Attachment L-14-198 Page 2of2 Perry Nuclear Power Plant 10 CFR 50.46 Changes and Errors (Continued)

Vendor Summary of Change/Error Licensing Basis Peak Licensee Report of Notification Clad Temperature (PCT) Notification Number Impact (Accession No.)

2014-01 Impact of use of a new PCT impact for GE14 This submittal version of SAFER04A. fuel is 0°F 2014-02 Impact of system mass PCT impact for GE14 This submittal divergence error. fuel is 0°F 2014-03 Impact of minimum delta PCT impact for GE14 This submittal pressure error. fuel is -15°F.

2014-04 Impact of counter current flow PCT impact for GE14 This submittal limitation (CCFL) error. fuel is 0°F TOTAL Summation of the absolute 125°F values of the changes/errors.

Notes: 1. SAFER - Name of the code developed by General Electric Company that calculates long term reactor vessel inventory and peak cladding temperature for LOCA and loss of inventory events.

2. WEVOL - Name of a code that is used to calculate the weight and volume inputs for jet pump plant SAFER analyses.

3.. LOCA - Loss of coolant accident.