ML19249B778

Enclosure 6 - Millstone Power Station, Unit 2, Comparison Matrix RCS Pot. Loss A.1

ML19249B778
Person / Time
Site:	Millstone, Surry, North Anna, 07200002, 07200055
Issue date:	08/29/2019
From:	Dominion Energy Nuclear Connecticut, Virginia Electric & Power Co (VEPCO)
To:	Office of Nuclear Material Safety and Safeguards, Office of Nuclear Reactor Regulation
References
19-296
Download: ML19249B778 (2)

Text

Serial No.: 19-296 Docket No.: 50-336 ENCLOSURE 6 MPS2 COMPARISON MATRIX RCS POT. LOSS A.1 Dominion Energy Nuclear Connecticut, Inc. (DENC)

Millstone Power Station Unit 2

Serial No.: 19-296 Docket Nos.: 50-336 Enclosure 6 Page 1 of 1 Table 4 - MPS2 Comparison Matrix Category F: Fission Product Barrier Degradation RCS RCS or SG Tube Leakage RCS Pot. 1. UNISOLABLE RCS or The pump capacity of a standby MPS2 positive Loss SG tube leakage > 50 P-Loss 1 A. Operation of a standby displacement charging pump, started on decreasing A.1 gpm excluding normal charging (makeup) pressurizer level, is not indicative of a potential loss of reductions in RCS pump is required by the RSC barrier. Control room indications are inventory (e.g.

EITHER of the following: available to provide the operator adequate capability letdown, RCP seal to maintain pressurizer level within specified limits and

1. UNISOLABLE RCS leakage) identify UNISOLABLE RCS or SG tube leakage> 50 leakage gpm excluding normal reductions in RCS inventory OR (e.g., letdown, RCP seal leakage).

2. SG tube leakage. The design flow of the MPS2 positive displacement OR charging pumps is 44 gpm. Decreasing pressurizer level would be indicative of a> 50 gpm leak rate with B. RCS cooldown rate two charging pumps running (88 gpm), a minimum greater than (site- design letdown flow of approximately 28 gpm and specific pressurized assumed RCP bleed off flow of up to 10 thermal shock gpm. Therefore, continued decreasing level with two criteria/limits defined by charging pumps running would not require operators site-specific to make a mass balance calculation. By contrast, two indications). charging pumps running and system level stabilized would likely indicate leakage < 50 gpm and not constitute an inability to maintain pressurizer level within specified limits.

MPS2 has implemented the alternative threshold wording consistent with NEI 99-01, Rev. 6, RCS Potential Loss 1, Developers Notes.