ML20072H327

LLC - Public Meeting Presentation: Topic - Emergency Core Cooling System Boron (ECCS) Distribution, PM-0320-69218, Revision 0

ML20072H327
Person / Time
Site:	NuScale
Issue date:	03/09/2020
From:	NuScale
To:	Office of Nuclear Reactor Regulation
Shared Package
ML20072H588	List: ML20072H327 ML20072H333
References
L0-0320-69219 PM-0320-69218, Rev 0
Download: ML20072H327 (9)

Text

L0-0320-69219

Enclosure:

"Public Meeting Presentation: Topic - Emergency Core Cooling System Boron (ECCS) Distribution,"

PM-0320-69218, Revision 0 NuScale Power, LLC 1100 NE Circle Blvd., Suite 200 Corvallis, Oregon 97330 Office 541.360-0500 Fax 541.207.3928 www.nuscalepower.com

NuScale Nonproprietary Public Meeting Presentation Topic Emergency Core Cooling System (ECCS) Boron Distribution March 9, 2020 PM-0320-69218 Revision: 0 Copyright 2020 by NuScale Power, LLC.

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Presenters Ben Bri$tol Supervisor, System Thermal-Hydraulics Matthew Presson Licensing Project Manager 2

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Agenda

• Boron Transport - Background and Discussion

• Boron Transport- Update and Resolution

• Conclusion 3

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ECCS Boron Transport - Background NuScale Response to RAI 8930 (ML19332A120) supports our priority to develop a safe and passive design

• FSAR 15.0.6.1 describes analyses which evaluate the transport of-boron to the core under postulated Chapter 15 events.

• Concludes that boron will concentrate in the core region, and that the 15.0.6 evaluation provides a bounding analysis.

• Supports NRC Staff safety evaluation discussion tllat:

- "core reactivity would not be adversely affected by boron redistribution to places outside the core, and therefore, would not return to power"

- Section 15.0.6.4.4 of the Chapter 15 Safety Evaluation Report (ML20027A108) 4 PM-0320-69218

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ECCS Boron Transport - Discussion Discussion for expanding the ECCS boron transport analysis:

• As boron accumulates in the core/riser region, boron concentration in the down comer and in containment decreases as steam is condensed and lower concentration water is recirculated in to the reactor vessel

- Boron precipitation analysis performed as part of ECCS long term cooling analysis

• Boron dilution analysis was performed to:

- Evaluate potential for lower boron concentration fluid in core or near core inlet

- Demonstrate that core region boron concentration remains above the initial concentration

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- Confirm the basis for the response to RAI 8930 Boron transport governed by:

• boiling in the core

• condensation in the containment vessel 5

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ECCS Boron Transport - Update/Resolution Update:

In preparation for Ch. 15 ACRS subcommittee meeting NuScale determined under certain conditions, ECCS actuated later than expected and resulted in higher containment water level accumulation than is considered in RAI 8930 response basis.

Resolution:

Lowering the containment high water level set point actuates ECCS earlier to reduce the initial containment water accumulation and maintain the RAI 8930 response basis.

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ECCS Boron Transport - Conclusions

• NuScale is highly committed to plant safety, and to providing a safe and passive design

• In supporting this commitment, NuScale's position is that this design change is appropriate to resolve as part of finalizing the DCA

• This change confirms the boron distribution analyses provided in FSAR 15.0.6.1, and maintains 15.0.6 as the bounding analysis for the NuScale design 7

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