ML101580445

Simplified Equation Status

ML101580445
Person / Time
Site:	Diablo Canyon
Issue date:	06/07/2010
From:	Lin A Nuclear Energy Institute, Pacific Gas & Electric Co
To:	NRC/NRR/DSS/SRXB
Lyon W, DSSA/SRXB, 415-2897
Shared Package
ML101580207	List: ML101580213 ML101580445
References
Download: ML101580445 (10)

Text

Simplified Equation Status NRC / NEI June 2, 2010 Anderson Lin PWROG Technical Lead Diablo Canyon Power Plant

PWROG Projects Simplified Gas Transport Equation Void Transport (WCAP-16631 for 6 & 8)

On Going 4 & 12 @ Purdue

• Static Pressure Water Hammer

• Buoyancy

• Pressure Pulsation

• Breaks down (OG-08-315)

• Transport Buffers Pipe p Hangers g

• Scaling of models Relief Valves

• Hot Recirc. & Containment Spray (OG-08-292)

Non-Condensable Gas into the Pump Interim Gas Ingestion Reactor Vessel Tolerance Criteria (V-EC-1866)

(OG-08-293)

• ECCS Delay

• Steady State & Transient Void Limits

• LOCA & Non-LOCA Qualitative Evaluation

• Types of Pumps

• Peak / Average Void Fraction

• Momentary TDH Degradation

• NPSHR vs. NPSHA

Gas Transport vs. Flow Rate Observation: Higher flow results in higher void fraction (over a shorter duration) being transported

Bounding Condition

1. Met Most Stringent Void Acceptance Criteria :

{ Highest Flowrate

{ Supported by Conservative Tested Void Condition

2. PIRT To Minimize The Initial Void Volume

{ Conservatively Limit to 5% (i.e., 11% test)

3. Minimize The Risk To Pump Operability

1. Likely Be Implementable at the Plant

Simplified Equation vs. APC Criteria Simplified Equation vs. DSS & APC Figure 6 6 inch 5% initial void fraction RIMP2 ( 11% initial void & Fr=1.9) 0.1 70% < BEP < 120%

0.09 10% for 5 Seconds 0.08 0.07 0.06 Void Fraction F060 F100 0.05 BEP < 70% or > 120 % Most Limiting F190 NRR 0.04 4.8 gallon Total Void Volume 0.03 0.02 0.01 0

0 5 10 15 20 25 30 Time (sec)

Methodology Consideration

1. Ratio = Q gas / Q mixture

{ Voids Must Mix With Water Results in A Much Lower Void Fraction To The Pump

2. Different Transport for 4, 4 , 6 6 & 8 8 and 12 12

{ Due to void size to Pipe X-Section Ratio

{ Void Formation Anomalies

{ Limited to Actual Pump Flow Ranges

Treatment of the Simplified Equation

1. Suction Headers With Takeoffs

{ Use Simplified Equation to calculate allowable void volume for each individual pump suction

{ Apply the smallest of the allowable void volume to the common suction header 2 Allowable Void Volume < 1/4 Of The Downstream 2.

Vertical Pipe Volume

3. Allowable void accounts for static pressure change between high point and pump suction

{ Elevation change must be > 10 feet

Advantages of the Simplified Equation

1. Simplified Equation is Conservative

{ Limits The Allowable Void Volume

{ Not Likely To Gas Bind The Pump

{ Provides Reasonable Basis for Pump Operability

{ Reasonable Engineering Judgment

{ Enveloped by DSS / APC Void Criteria

{ Supported by the Purdue Test Data

2. Simple Method To Determine Allowable Void Volume At Any Pump - All Safety Related Pumps

Status zPurdue Test Report Issued by July 31 zSimplified Report Issued by August 16, 2010 zFuture Work May Relax Void Limit on Common Suction Header