ML15302A118

NEDC-33347P Rev.1 RAI Letter

ML15302A118
Person / Time
Site:	Boiling Water Reactor Owners Group
Issue date:	11/09/2015
From:	Kevin Hsueh Licensing Processes Branch (DPR)
To:	Leslie Hill Southern Nuclear Operating Co
Drake J
References
NEDC-33347P, Rev 1, TAC MF6708
Download: ML15302A118 (6)

Text

November 9, 2015 Ms. Lesa P. Hill, Chairman Boiling Water Reactor Owners Group Southern Nuclear Operating Company c/o GE Hitachi Nuclear Energy P.O. Box 780 3901 Castle Hayne Road, M/C F-12 Wilmington, NC 28402

SUBJECT:

REQUEST FOR ADDITIONAL INFORMATION RE: BOILING WATER REACTOR OWNERS GROUP TOPICAL REPORT NEDC-33347P, REVISION 1, CONTAINMENT OVERPRESSURE CREDIT FOR NET POSITIVE SUCTION HEAD (NPSH) (TAC NO. MF6708)

Dear Ms. Hill:

By letter dated November 21, 2014 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML14325A626), the Boiling Water Reactor Owners Group (BWROG) submitted for U.S. Nuclear Regulatory Commission (NRC) staff review Topical Report NEDC-33347P, Revision 1, Containment Overpressure Credit for Net Positive Suction Head (NPSH). Upon review of the information provided, the NRC staff has determined that additional information is needed to complete the review. On November 2, 2015, BWROG Project Manager, Kenneth Welch, agreed that the NRC staff will receive your response to the enclosed Request for Additional Information (RAI) questions by December 28, 2015.

If you have questions regarding this matter, please contact Jason Drake at 301-415-8378 or via e-mail at Jason.Drake@nrc.gov.

Sincerely,

/RA/

Kevin Hsueh, Chief Licensing Processes Branch Division of Policy and Rulemaking Office of Nuclear Reactor Regulation Project No. 691

Enclosure:

RAI Questions

ML15302A118 NRR-106 OFFICE NRR/DPR/PLPB NRR/DPR/PLPB NRR/DSS/SCVB NRR/DPR/PLPB NAME JDrake DHarrison (ABaxter for)

RDennig KHsueh DATE 11/4/2015 11/04/15 11/4/2015 11/9/2015

Enclosure REQUEST FOR ADDITIONAL INFORMATION OFFICE OF NUCLEAR REACTOR REGULATION NEDC-33347P, REVISION 1, CONTAINMENT OVERPRESSURE CREDIT FOR NET POSITIVE SUCTION HEAD (NPSH)

BOILING WATER REACTOR OWNERS GROUP PROJECT NO. 691 The Nuclear Regulatory Commission (NRC) staff has the following requests for the topical report NEDC-33347P, Revision 1 (Reference 1):

1.

SECY-11-0014, Use of Containment Accident Pressure in Reactor Safety Analysis, (Reference 4), Section 1.0, page 2, states that containment overpressure was an earlier term used for the pressure developed inside the containment during an accident.

The NRC staff decided to replace this term with containment accident pressure for two reasons: (1) the industry uses several definitions of containment overpressure, and (2) it has been confused with over-pressurizing the containment. The containment design pressure is never exceeded while crediting the pressure developed during an accident. The staff requests either of the following:

(a) Replace the term Containment Overpressure with Containment Accident Pressure in the title and throughout the topical report.

(b) Add a statement in Section 1.0, Introduction, indicating that the term Containment Overpressure is meant to be Containment Accident Pressure, which are defined as the pressure developed inside the containment during a design-basis accident or a special event.

2.

The revised draft safety evaluation report (SER) sent by letter dated March 10, 2010 (Reference 3), was issued after the NRC staff resolved the Boiling Water Reactor Owners Group (BWROG) comments on the draft SER transmitted by letter dated September 29, 2009 (Reference 2). The Figure 2, Flow Diagram for Deterministic and Statistical Containment Analysis Approved by the NRC staff, in the revised draft SER (Reference 3),

has been modified and will be replaced in the final SER with Figures 1, a, and b, as enclosed, which define the containment analysis licensing bases for use of containment accident pressure approved by the NRC staff. These Figures are the same as those provided to the BWROG in letter dated February 25, 2013 (Reference 7). Please provide your comment on factual errors or clarity concerns contained in these Figures.

Use alternate methods subject to NRC approval or modify plant.

C Perform Monte Carlo 95/95 containment analysis to justify (ht - hmin) CAP head used > (hvp-hmin)

Perform conservative transient NPSH analysis assuming ht hatm > hmin.

Perform conservative containment analysis for NPSH.

NPSHA NPSHReff

[CAP (2) used = 0]

(3)

A & C is the design basis analysis A & B is the design basis analysis.

A NPSHA NPSHReff D

Notes

1. Pool refers to suppression pool for BWRs.

2. Containment accident pressure (CAP) is defined as the transient absolute pressure developed above pool surface during the accident minus the minimum allowed technical specification (TS) absolute pressure above pool surface during normal operation; therefore CAP head available = (ht - hmin)

3. Containment leakage monitoring for a pre-existing leak during normal operation is not required.

4. Containment leakage monitoring for a pre-existing leak during normal operation is required.

Perform conservative transient NPSH analysis assuming hatm = hmin for Tp Tsat

& hatm hvp for Tp > Tsat Perform conservative transient NPSH analysis assuming hatm = hmin.

B NPSHA < NPSHReff Perform conservative transient NPSH analysis assuming hatm (95/95 value of ht obtained from Monte Carlo containment analysis).

NPSHA < NPSHReff NPSHA < NPSHReff FIGURE 1: FLOW CHART FOR LOCA CONTAINMENT AND NPSH ANALYSES A & D is the design basis analysis NPSHA < NPSHReff Symbols hatm = Absolute pressure head above pool(1) surface hmin = Minimum absolute TS pressure head above pool surface during normal operation hvp = Transient absolute vapor pressure head at pool temperature during accident ht = Transient absolute pressure head above pool surface during accident Tp = Transient pool temperature during accident Tsat = Saturation temperature at hmin Tpmax = Peak pool temperature during accident NPSHA = Available NPSH NPSHReff = NPSHR3% + Uncertainty NPSHA NPSHReff

[CAP head used (hvp - hmin)]

(3)

NPSHA NPSHReff

[ht - hmin) CAP head used >

(hvp-hmin)]

(4)

Tpmax >

Tsat YES (See Figure a)

NO (See Figure b) hatm CAP head available Time from LOCA ht hvp hvp ht hatm CAP head available Figure a: Illustration of hatm and CAP Head Available for Tpmax > Tsat Figure b: Illustration of hatm and CAP Head Available for Tpmax < Tsat Time from LOCA hmin hmin REFERENCES

1.

Letter from Boiling Water Reactor Owners Group (BWROG) to NRC dated November 21, 2014, Submittal of Revised BWROG Topical Reports NEDC-33347P, Revision 1 (Proprietary Version), and NEDO-33347, Revision 1 (Non-Proprietary Version),

Containment Overpressure Credit for Net Positive Suction Head (NPSH) (ADAMS Accession No. ML14325A626).

2.

Letter from NRC to BWROG dated September 29, 2009, Draft Safety Evaluation of Boiling Water Reactors Owners Group (BWROG) Topical Report NEDC-33347, Revision 0, Containment Overpressure Credit for Net Positive Suction Head (NPSH) (TAC No.

MD8146) (ADAMS Accession No. ML092440176).

3.

Letter from NRC to BWROG dated March 10, 2010, Revised Draft Safety Evaluation of Boiling Water Reactors Owners Group (BWROG) Topical Report NSEDC-33347, Revision 0, Containment Overpressure Credit for Net Positive Suction Head (NPSH)

(TAC No. MD8146) (ADAMS Accession No. ML100680573).

4.

SECY-11-0014, Enclosure 1, Use of Containment Accident Pressure in Reactor Safety Analysis (ADAMS Accession No. ML102110167).

5.

Letter from BWROG to NRC dated October 24, 2012, Submittal of BWROG Technical Reports Addressing the NRC Guidance Document on the Use of Containment Accident Pressure (CAP) in Analyzing Emergency Core Cooling System (ECCS) and Containment Heat Removal System Pump Performance in Postulated Accidents (ADAMS Accession No. ML123000308).

6.

Letter from BWROG to NRC dated March 18, 2014, Submittal of BWROG Technical Reports Addressing the NRC Guidance Document on the Use of Containment Accident Pressure (CAP) in Analyzing Emergency Core Cooling System (ECCS) and Containment Heat Removal System Pump Performance in Postulated Accidents - CVIC Pumps (ADAMS Accession No. ML14077A088).

7.

Letter from NRC to BWROG dated February 25, 2013, Use of Containment Accident Pressure in Demonstrating Acceptable Operation of Emergency Core Cooling System and Containment Heat Removal Pumps During Postulated Accidents (ADAMS Accession No. ML13016A013).