ML100470947

From kanterella
Jump to navigation Jump to search
Simplified Equation for Gas Transport to Pumps
ML100470947
Person / Time
Site: Diablo Canyon  Pacific Gas & Electric icon.png
Issue date: 01/21/2010
From: Lin A, Swantner S
Pacific Gas & Electric Co, Westinghouse
To:
Office of Nuclear Reactor Regulation
Lyon W, DSSA/SRXB, 415-2897
Shared Package
ML100480102 List:
References
Download: ML100470947 (24)
v • d • e


Text

Simplified Equation for Gas Transport To Pumps NEI Workshop January 21, 2010 Anderson Lin / Diablo Canyon Power Plant Steve Swantner / Westinghouse

What Factors Could Result In Gas Generation ?

  • Temperature
  • Pressure

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

On Going 4 & 12 @ Purdue

  • Buoyancy
  • Pressure Pulsation
  • Breaks down (OG-08-315)
  • Transport Buffers Pipe p Hangers g
  • Scaling of models Relief Valves

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

(OG-08-293)

  • LOCA & Non-LOCA Qualitative Evaluation
  • Types of Pumps
  • Peak / Average Void Fraction
  • Momentary TDH Degradation
  • NPSHR vs. NPSHA

Gas Transport vs. Flow Rate Observation 1: Higher flow results in higher void fraction (over a shorter duration) being transported

Test Loop at Purdue: Video Locations Top Horizontal Top Vertical Bottom Vertical Bottom Horizontal

Gas Transport vs. Flow Rate Observation 2: Larger initial void volume results in larger void Fraction being transported

Identify Critical Parameters zObservations:

{Higher flow Higher Void

{Larger initial void volume Higher Void zMinimizing Void Transport to The Pump

{Identify the maximum flow rate

{Limit the allowable initial void

Simplified Equation vs. APC Criteria Gas Transport vs. Flow Rate

{ Limit the allowable initial void Simplified Equation To Limit The Initial Void (Easy For Plant Implementation)

V allowable = Q max X X t X ( Pp/P1)

V allowable : Determines the Void Fraction

( If X t = 0 No void at all )

What are the appropriate & t Gas Volume ?

Void Limit vs Pump Tolerance Pump Operability Void Size Type of Pumps &

Cost of Pump Tests

Void Impact To the Pump zPump Performance Considerations

{Relies on incompressible water to do work zHigher Void Fraction (less working fluid) Less TDH

{Void expands as it approaches the eye of the impeller zPtotal = Constant = PStatic + P1/2 V2 = Plocal + Pkinetic z As Pkinetic increases, Plocal decreases Void Vol. Increases

{Plocal >> Pvapor Issue is not NPSHr (cavitation) but a flow passage issue

{Void Fraction To The Pump Must Be Limited

Continuous Pump Test Curve Ref: POWER 2009-81175

Continuous Pump Test Curve

( At least 3 test data points for a test curve)

Ref: NUREG / CR 2792 Atmospheric Suction Pressure

Continuous Pump Test Curve

( At least 3 test data points for a test curve)

Ref: NUREG / CR 2792 50 psig Suction Pressure

Multistage Is More Tolerant Than Single Stage Pump Ref: NUREG / CR 2792

Void Impact To the Pump z A Small, Limited Void Should Be Tolerable

{Pump Curve Typically Breaks Down After 20% -

40% void

{Available Pump Tests Suggest Void Tolerance to 10% - 20% (based on the available suction pressure) zEffect Is a Continuous Degradation of the Pump Curve zThe Pump Will Continue to Operate (No Gas Binding)

Void Impact To the Pump z A Small, Limited Void May Be Tolerable

{ Pump Curve Typically Breaks Down After 20% - 40% Void

{ Available Pump Tests Suggest Void Tolerance Between 10% - 20% (based on the available suction pressure) z Simplified Equation Vallowable = Qmax X X t X ( Pp/P1) z Simplified Equation Conservative Volume

{ No Continuous Void Source in the ECCS

{ Void Passage Through Pump Is A Momentary Condition

{ ECCS Pumps have High Suction Pressure z Injection phase full RWST static head z Recirc. Phase Static head + containment P - screen P

Peak Void from the 6 Loop Test Peak Void from the 12 Loop Test Identify the Maximum Flow Rate ECCS Suction ID Q-max Fr -max Pumps (inch) (gpm)

CCP 6.357 560 1.37 SIP 6.357 670 1.64 HPSI 10.25 1410 1.05 RHRP 12.25 4500 2.14 LPSI 18 5500 1.00

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)

Simplified Allowable Void Equation z Static Void < 5% for smaller pipes, <2% for larger pipes z Vallowable = Qmax X X t X ( Pp/P1)

Pipe ID X-Section (Static t Conditions)

< 12 10% 5 second < 5%

> 12 2% 20 second < 2%

Examples of Allowable Void From The Simplified Equation z Static Void < 5% for smaller pipes, <2% for larger pipes z Vallowable = Qmax X X t X ( Pp/P1)

Pumps Q max V allowable X-Section t

CCPs 560 10% 5 second 4.67 gal < 5%

SIPs 670 10% 5 second 5.58 gal < 5%

RHRPs 4500 2% 20 second 30 gal < 2%

HPSI 1800 10% 5 second 12 gal < 5%

LPSI 5500 2% 20 seconds 36 gal < 2%

Purdue -8 psig: 5% 4.8 gal & 10% 9.7 gal

Treatment of the Simplified Equation z Supply Headers with Takeoffs

{Calculate allowable volume for each individual pump suction

{Apply smallest of the allowable branch line limits to the header z Vertical pipe volume > 4 X Void volume z Allowable void accounts for static pressure change between high point and pump suction

{Elevation change must be > 10 feet

Advantages of the Simplified Equation z Simplified Equation is Conservative

{ Limits The Allowable Void Volume

{ Allowable Void volumes < Purdue Tested

{ Not Likely To Gas Bind The Pump

{P id R

{Provides Reasonable bl BBasis i ffor P Pump O Operability bilit

{Reasonable Engineering Judgment

{Enveloped by DSS / APC Void Criteria

{Supported by the Purdue Test Data z Easily Implemented In ECCS Surveillance Acceptance Criteria

{Simple Method to Define Allowable Void Volume

Retrieved from "https://kanterella.com/w/index.php?title=ML100470947&oldid=2137097"