ML100470947
| ML100470947 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| 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) | |
Text
Simplified Equation for Gas Transport To Pumps NEI Workshop Anderson Lin / Diablo Canyon Power Plant Steve Swantner / Westinghouse NEI Workshop January 21, 2010
What Factors Could Result In Gas Generation ?
- Temperature
- Pressure
PWROG Projects Void Transport (WCAP-16631 for 6 & 8)
On Going 4 & 12 @ Purdue
- Static Pressure
- Buoyancy
- Breaks down
- Transport Buffers Scaling of models Water Hammer
- Pressure Pulsation (OG-08-315)
Pipe Hangers Simplified Gas Transport Equation Pump Interim Gas Ingestion Tolerance Criteria (V-EC-1866)
- Steady State & Transient Void Limits
- Types of Pumps
- Peak / Average Void Fraction
- Momentary TDH Degradation
- NPSHR vs. NPSHA
- Scaling of models p
g Relief Valves
- Hot Recirc. & Containment Spray (OG-08-292)
Non-Condensable Gas into the Reactor Vessel (OG-08-293)
- ECCS Delay
- LOCA & Non-LOCA Qualitative Evaluation
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)
(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 V 2 = 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 zInjection phase full RWST static head zRecirc. 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 Pumps Suction ID (inch)
Q-max (gpm)
Fr -max 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 70% < BEP < 120%
10% for 5 Seconds
( 11% initial void & Fr=1.9)
Figure 6 6 inch 5% initial void fraction RIMP2 0.07 0.08 0.09 0.1 BEP < 70% or > 120 %
4.8 gallon Total Void Volume Most Limiting 0
0.01 0.02 0.03 0.04 0.05 0.06 0
5 10 15 20 25 30 Time (sec)
Void Fraction F060 F100 F190 NRR
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
t X-Section (Static 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
t V allowable X-Section Pumps max
t allowable 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 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
bl B
i f P
O bilit
{Provides Reasonable Basis for Pump Operability
{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