ML18201A406

Plants, Units 1 and 2 - Exelon'S Response to NRC Questions

ML18201A406
Person / Time
Site:	Calvert Cliffs
Issue date:	06/21/2018
From:	Villar E H Exelon Generation Co
To:	Marshall M Plant Licensing Branch 1
Marshall M L, NRR/DORL/LPLI, 415-2871
References
CAC MF8521, CAC MF8522, EPID L-2016-LRM-0001
Download: ML18201A406 (2)

Text

From: Villar, Enrique:(GenCo-Nuc)

To: Marshall, Michael

Subject:

[External_Sender] Exelon"s response to NRC questions Date: Thursday, June 21, 2018 8:47:03 AM Michael, Below are Exelon's response to the NRC questions for this afternoon call. If you have any questions or need further clarification on any of them, please let me know. Answers to NRC questions on the use of risk metrics for sump operability determinations.

1. Is Exelon proposing to use risk metrics to decide whether CONDITION A of LCO 3.6.9 (Slide

1) is met or satisfy REQUIRED ACTION A.3 of LCO 3.6.9?

Yes, Exelon is proposing to use risk metrics to decide whether CONDITION A of LCO 3.6.9 is met 2. What are the analyzed limits mentioned in CONDITION A of LCO 3.6.9 (Slide 1), and are the analyzed limits risk metrics are deterministic parameters?

For this proposal the analyzed limits are risk metrics, CDF and LERF based on deterministic parameters.

3. How is the use of risk metrics risk-informed (i.e., is the use risk-based or risk-informed)?

The use of the risk metrics is risk-informed.

It is a combination of risk-based metrics (CDF and LERF from the PRA) and deterministic considerations (debris quantities and debris quantities to determine CDF and LERF from the GSI-191 NARWHAL model).

4. Does Exelon consider its planned use of risk consistent with the guidance in IMC 0326 on use of PRA and operability determinations.

The operability of the containment emergency recirculation sump at Calvert Cliffs will be based on a risk-informed assessment after the Risk-Informed GSI-191 license amendment is granted, consistent with the STP Pilot Project.

This same risk-informed assessment will be used as the basis for deciding whether CONDITION A of LCO 3.6.9 is met.

The quantitative evaluation is not performed using the plant-specific PRA.

Therefore, Exelon considers the planned use of risk consistent with the guidance in IMC 0326 on use of PRA and operability determinations.

Thanks Ehv Enrique (Rick) Villar Sr Licensing Engineer Enrique.Villar@exeloncorp.com Office # (610) 765-5736 Cell # (610) 368-5135 This Email message and any attachment may contain information that is proprietary, legally privileged, confidential and/or subject to copyright belonging to Exelon Corporation or its affiliates

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