16 th Annual RETS/REMP Workshop 26-28 June 2006 Mashantucket, CT By Frank M. Gavila STP Has a Different Meaning to Different People

1616thth Annual RETS/REMP Workshop Annual RETS/REMP Workshop26-28 June 200626-28 June 2006

Mashantucket, CTMashantucket, CT

By Frank M. GavilaBy Frank M. Gavila

STP Has a Different Meaning to Different People

OverviewOverview

1.1. Introduction to Ideal Gas LawsIntroduction to Ideal Gas Laws2.2. Concept of reference temperature and pressure for Concept of reference temperature and pressure for

comparison of two different gas volumes or two comparison of two different gas volumes or two different flowratesdifferent flowrates

3.3. Definitions of various recognized reference to T and Definitions of various recognized reference to T and P’sP’s

4.4. How does REMP or RETS air sampling activities get How does REMP or RETS air sampling activities get involved with reference T and P issues?involved with reference T and P issues?

5.5. Regulatory references or standardsRegulatory references or standards6.6. SolutionsSolutions

Introduction to the Ideal Gas LawsIntroduction to the Ideal Gas Laws

1.1. Introduction to the Ideal Gas LawsIntroduction to the Ideal Gas Laws

I.I. Gas Law BasicsGas Law Basics

A.A. GasesGases

In the gas phase, molecules are relatively In the gas phase, molecules are relatively far apart. This makes gases very far apart. This makes gases very compressible.compressible.

A gas expands to fill the volume of its A gas expands to fill the volume of its container.container.

Gases are usually measured by volume Gases are usually measured by volume so a relationship between so a relationship between volumevolume and and number of molesnumber of moles is needed. is needed.

Introduction to the Ideal Gas Laws Introduction to the Ideal Gas Laws (cont.)(cont.)

B.B. The Gas LawsThe Gas Laws

The gas laws are experimental The gas laws are experimental relationships among pressure (P), volume relationships among pressure (P), volume (V), temperature (T) and moles (n).(V), temperature (T) and moles (n).

- Boyle’s Law (V,P)- Boyle’s Law (V,P)

- Charle’s Law (V,T)- Charle’s Law (V,T)

- Avogadro’s Law (V,n)- Avogadro’s Law (V,n)

- Ideal Gas Law (V,P,T,n)- Ideal Gas Law (V,P,T,n) All gases behave similarly. The gas laws All gases behave similarly. The gas laws

assume ideal behavior.assume ideal behavior.


C.C. Boyle’s LawBoyle’s Law

In 1662, Robert Boyle discovered that In 1662, Robert Boyle discovered that volume is inversely proportional to volume is inversely proportional to pressurepressure

V ∞ V ∞ 11 (constant T, n) (constant T, n)

PP

Atmospheric pressure

Gas

Volume – 60 mL Hg

added

760 mm

Volume – 30 mL


D.D. Charles’ LawCharles’ LawLord Kelvin proposed an absolute Lord Kelvin proposed an absolute temperature scale defined by temperature scale defined by T(K) = T(C)+273.15T(K) = T(C)+273.15

Expressed in absolute temperature, Charles’ Expressed in absolute temperature, Charles’ law is:law is:V ∞ T (constant P, n)V ∞ T (constant P, n)

Charles discovered that volume is directly Charles discovered that volume is directly proportional to temperature.proportional to temperature.

The volume of a gas extrapolates to zero at The volume of a gas extrapolates to zero at -273 -273 ooC. This must be the lowest C. This must be the lowest temperature possible.temperature possible.



E.E. Avogadro’s LawAvogadro’s Law

In 1811, Avogadro proposed that: Equal In 1811, Avogadro proposed that: Equal volumes of gases at the same temperature volumes of gases at the same temperature and pressure contain equal numbers of and pressure contain equal numbers of molecules.molecules.

It follows that the volume of a gas at It follows that the volume of a gas at constant temperature and pressure is constant temperature and pressure is proportional to the number of moles.proportional to the number of moles.

V ∞ n (constant T, P)V ∞ n (constant T, P)


F.F. The Ideal Gas EquationThe Ideal Gas Equation

Combining the gas laws gives:Combining the gas laws gives:

V ∞ V ∞ nTnT or V=R or V=R nTnT

P PP P

Where R is called the Gas constant:Where R is called the Gas constant:

R = 0.08206 R = 0.08206 L L .. atm atm

mol . Kmol . K

The Ideal gas law is usually written as:The Ideal gas law is usually written as:

PV = nRTPV = nRT


Processes Involving Ideal GasesProcesses Involving Ideal Gases

Let’s describe a process by which an ideal gas is Let’s describe a process by which an ideal gas is transferred from conditions at State 1 to conditions transferred from conditions at State 1 to conditions at State 2at State 2

(Actual Conditions)(Actual Conditions) State 1State 1 State 2State 2 (Reference Conditions)(Reference Conditions)

or: or: P P11, V, V11, n, n11, T, T11 P P22, V, V22, n, n22, T, T22

State 1: PState 1: P11VV11 = n = n11RTRT1 1 State 2: PState 2: P22VV22 = n = n22RTRT22


Solving for R:Solving for R:

R= PR= P11VV11 = P = P22VV22

nn11TT11 n n22TT22

If the number of moles stays constant (nIf the number of moles stays constant (n11 = n = n22))

PP22VV22 = P = P11VV11 or or P P ReReff . V . VReRef = f = PPACTACT . V . VACT ACT

TT22 T T11 T T ReRef f TTACT ACT


Thus Thus VVREFREF = V= VACTACT P PACTACT . T . TReReff

PPReReff T TACTACT


2.2. Concept of Reference Temperature and PressureConcept of Reference Temperature and Pressure

In order to compare the volumes of the same gas or In order to compare the volumes of the same gas or the corresponding gas flowrate (volume/unit time) of the corresponding gas flowrate (volume/unit time) of two different gas samples, it is necessary to ensure two different gas samples, it is necessary to ensure that the T and P are the same for both gas volumes or that the T and P are the same for both gas volumes or flowrates.flowrates.

This results in the ideal gas law equation This results in the ideal gas law equation

V = n V = n RTRT = n . k = n . k PP


Therefore, the volume of the gas is only a function of the Therefore, the volume of the gas is only a function of the number of moles of gas present in each of the two number of moles of gas present in each of the two different samples collected different samples collected assuming the pressure and assuming the pressure and temperature are the same.temperature are the same.

It is erroneous to compare two different volumes of the It is erroneous to compare two different volumes of the same gas without comparing these volumes at the same same gas without comparing these volumes at the same reference temperature and pressure. The same applies reference temperature and pressure. The same applies to flowrates (volume/unit time).to flowrates (volume/unit time).


3.3. Commonly Utilized Reference T and P for Testing and Commonly Utilized Reference T and P for Testing and Documentation of Chemical and Physical ProcessesDocumentation of Chemical and Physical Processes

A.A. Standard Temperature and Pressure (Classical)Standard Temperature and Pressure (Classical)

STP – Standard Temperature and Pressure is defined as STP – Standard Temperature and Pressure is defined as air at:air at:T = 0T = 0ooC (273.15C (273.15ooK) or 32K) or 32ooF (460F (460ooR)R)P = 1 Atmosphere (atm) or 760 torr, 14.7 psia, P = 1 Atmosphere (atm) or 760 torr, 14.7 psia, 29.92 in. Hg, 101.325 kPa29.92 in. Hg, 101.325 kPa

Approximate freezing point of water and atmospheric Approximate freezing point of water and atmospheric pressure at sea level.pressure at sea level.


B.B. Normal Temperature and PressureNormal Temperature and Pressure

NTP – Normal Temperature and Pressure is defined NTP – Normal Temperature and Pressure is defined as air at:as air at:T= 20T= 20ooC (293.15C (293.15ooK), 68K), 68ooFFP = 1 atm. 14.7 psia, 760 mm Hg, 29.92 in Hg, P = 1 atm. 14.7 psia, 760 mm Hg, 29.92 in Hg, 101.325 kPa101.325 kPa

NTP is common for testing and documentation of fan NTP is common for testing and documentation of fan capacitiescapacities


C.C. Standard Ambient Temperature and PressureStandard Ambient Temperature and Pressure

SATP – Standard Ambient Temperature and Pressure SATP – Standard Ambient Temperature and Pressure is defined as air at:is defined as air at:

T = 25T = 25ooC (298.15C (298.15ooK), 77K), 77ooFF

P = 101 kPa (1 atm.)P = 101 kPa (1 atm.)

The temperature and pressure where The temperature and pressure where

the equilibrium constant for the auto ionization of water the equilibrium constant for the auto ionization of water is 1.0 x10is 1.0 x10-14-14


D.D. International Standard Atmosphere International Standard Atmosphere ISA - International Standard Atmosphere is defined as ISA - International Standard Atmosphere is defined as air at sea level where:air at sea level where:T = 15T = 15ooC (59C (59ooF)F)P = 101.325 kPa, 1 atm.P = 101.325 kPa, 1 atm.RH = 0%RH = 0%

ISA is utilized a a reference for aircraft performance ISA is utilized a a reference for aircraft performance figures such as endurance, range, airspeed and fuel figures such as endurance, range, airspeed and fuel consumption.consumption.


E.E. Army Standard Metro AtmosphereArmy Standard Metro AtmosphereASM – Army Standard Metro atmosphere is defined as ASM – Army Standard Metro atmosphere is defined as sea level conditions of:sea level conditions of:T = 15T = 15ooC (59C (59ooF)F)P = 750 mm Hg (29.5275 in Hg)P = 750 mm Hg (29.5275 in Hg)RH = 78%RH = 78%

Utilized only for ballisticsUtilized only for ballisticsUS Army Ballistic Research Laboratory Aberdeen US Army Ballistic Research Laboratory Aberdeen Proving GroundProving Ground


F.F. Modified Normal Temperature and Pressure Modified Normal Temperature and Pressure (USA only)(USA only)

T = 70T = 70ooF (21.1F (21.1ooC)C)

P = 1 atm.; 29.92 in. Hg, 760 mm HgP = 1 atm.; 29.92 in. Hg, 760 mm Hg


G.G. Mass Flow Reference ConditionsMass Flow Reference Conditions

The mass flow of a gas is defined as the rate at which The mass flow of a gas is defined as the rate at which mass crosses an imaginary cross-sectional area in a mass crosses an imaginary cross-sectional area in a conduitconduit..

Typical units for mass flow can be:Typical units for mass flow can be:

• Grams per minute or kilograms per hourGrams per minute or kilograms per hour• Pounds per second or pounds per hourPounds per second or pounds per hour


True Mass Flow (M) can also be obtained by True Mass Flow (M) can also be obtained by measurement of volumetric flow at any T and P and measurement of volumetric flow at any T and P and converting the volumetric flow to the refernce classical converting the volumetric flow to the refernce classical STP conditions of 0STP conditions of 0ooC and 1 atm and multiplying by the C and 1 atm and multiplying by the gas density of classical STP. This is represented by the gas density of classical STP. This is represented by the following formula:following formula:


True Mass Flow (M) = Q . True Mass Flow (M) = Q . TsTs . . PaPa . . ρρgg = M = Mvv. . ρρgg Ta Ta PsPs

WhereWhereQ = Volumetric flowrate at actual T and P conditionsQ = Volumetric flowrate at actual T and P conditions

TTss = Absolute T @ standard condition in Kelvin = Absolute T @ standard condition in Kelvin

(273.15(273.15ooK)K)

TTaa = Absolute T @ flow condition in Kelvin = Absolute T @ flow condition in Kelvin

PPss = Absolute pressure at standard conditions (1 atm) = Absolute pressure at standard conditions (1 atm)

PPaa = Absolute pressure at flow conditions = Absolute pressure at flow conditions

ρρgg = Density of gas at classical STP conditions ( 0 = Density of gas at classical STP conditions ( 0ooC, 1 C, 1

atm)atm)


To convert to mass flow (MTo convert to mass flow (Mvv) in volumetric units from flow ) in volumetric units from flow

at actual conditions use the following formula:at actual conditions use the following formula:

MMv = v = Q . Q . TsTs . . PaPa

Ta PsTa Ps

Where Mv = Mass flow in volumetric units at STP (0Where Mv = Mass flow in volumetric units at STP (0ooC, C,

1 atm)1 atm)

The density of various gases at STP is presented on the The density of various gases at STP is presented on the next slide.next slide.

Density of Gases at STP Density of Gases at STP (0(0ooC, 1 ATM)C, 1 ATM)

GasGas Density (g/L)Density (g/L)

Air, dryAir, dry 1.29291.2929

AmmoniaAmmonia 0.7710.771

Carbon dioxideCarbon dioxide 1.9771.977

Carbon monoxideCarbon monoxide 1.2501.250

ChlorineChlorine 3.2143.214

Dinitrogen monoxide Dinitrogen monoxide 1.9771.977

Ethyne (acetylene)Ethyne (acetylene) 1.1711.171

HeliumHelium 0.17850.1785

HydrogenHydrogen 0.08990.0899

Density of Gases at STP Density of Gases at STP (0(0ooC, 1 ATM) (cont.)C, 1 ATM) (cont.)

GasGas Density (g/L)Density (g/L)

Hydrogen chlorideHydrogen chloride 1.6391.639

MethaneMethane 0.71650.7165

Sulphur dioxideSulphur dioxide 2.9272.927

NitrogenNitrogen 0.7160.716

Nitrogen monoxideNitrogen monoxide 1.2511.251

OxygenOxygen 1.4291.429


To compute True Mass Flow (M) multiply MTo compute True Mass Flow (M) multiply Mvv by the by the

density of the gas at 0density of the gas at 0ooC, 1 atm.C, 1 atm.

True Mass Flow (M) = MTrue Mass Flow (M) = Mvv . . ρρgg

Mass flow sensors which are currently utilized for many Mass flow sensors which are currently utilized for many airflow measurements are generally reporting volumetric airflow measurements are generally reporting volumetric flow values at 0flow values at 0ooC, 1 atm (classical STP). These C, 1 atm (classical STP). These volumes can easily be corrected to any reference T and volumes can easily be corrected to any reference T and P utilizing the gas law formulas.P utilizing the gas law formulas.


4.4. The RETS/REMP air monitoring specialist gets The RETS/REMP air monitoring specialist gets involved with reference T and P issues simply by the involved with reference T and P issues simply by the fact he is making flow measurements for purposes of fact he is making flow measurements for purposes of determining volumes of air passing through particulate determining volumes of air passing through particulate and/or radioiodine collection cartridges over a duration and/or radioiodine collection cartridges over a duration of time (sample duration).of time (sample duration).

He then integrates the volume measurements with He then integrates the volume measurements with radioactivity analysis in downstream calculations to radioactivity analysis in downstream calculations to determine radioactivity concentrations (radioactivity per determine radioactivity concentrations (radioactivity per unit volume).unit volume).


The volume of the samples is determined by either by The volume of the samples is determined by either by calculation of flowrate (measured by typically a calculation of flowrate (measured by typically a rotameter) multiplied by elapsed sample time or by the rotameter) multiplied by elapsed sample time or by the difference between ending and beginning reading on a difference between ending and beginning reading on a volume totalizer (such as a dry gas test meter). Some volume totalizer (such as a dry gas test meter). Some facilities employ volume totalizer systems that display facilities employ volume totalizer systems that display the calculated volume corrected to a reference T and P.the calculated volume corrected to a reference T and P.


It is evident that the temperature of the air sample is a It is evident that the temperature of the air sample is a function of the:function of the:

Geographical locationGeographical location ElevationElevation Season of year and Season of year and Time of dayTime of day


The absolute pressure of the air sample is a function of The absolute pressure of the air sample is a function of the elevationthe elevation the short term local atmospheric weather the short term local atmospheric weather

conditions that influences the local barometric conditions that influences the local barometric pressurepressure

the pressure drop of the filter(s) utilizedthe pressure drop of the filter(s) utilized the inherent sample system line losses attributing the inherent sample system line losses attributing

to pressure drop and to pressure drop and dust loading, if any.dust loading, if any.


The above expected variations in both T and P which a The above expected variations in both T and P which a large number of users will experience at approximately large number of users will experience at approximately 60 different plant sites in the USA will result in sample 60 different plant sites in the USA will result in sample volume determinations that are not truly comparable with volume determinations that are not truly comparable with each other and thus any calculated results involvng each other and thus any calculated results involvng these volumes are not in and of themselves comparable these volumes are not in and of themselves comparable to each other. Of concern is that in the vast majority of to each other. Of concern is that in the vast majority of cases, no data is being collected to enable a future cases, no data is being collected to enable a future correction of data even if such an adjustment were correction of data even if such an adjustment were required after the sample event.required after the sample event.

SolutionSolution

The only way to ensure reliability of comparison of data The only way to ensure reliability of comparison of data between air monitoring results published by USA NPP is between air monitoring results published by USA NPP is to report all measured or calculated volumes to a to report all measured or calculated volumes to a mutually agreed upon reference T and P. This will mutually agreed upon reference T and P. This will remove the data inconsistency due to geographical remove the data inconsistency due to geographical elevation, seasonal variations, uniqueness of sample elevation, seasonal variations, uniqueness of sample systems, differences in pressure drop of filters utilized, systems, differences in pressure drop of filters utilized, local dust loading, etc.local dust loading, etc.

SolutionSolution

What should be the Reference T and P?What should be the Reference T and P?

Four good options are:Four good options are: STPSTP SATPSATP NPT NPT MNPTMNPT

SolutionSolutionIs there a precedent,regulatory guideline,or Is there a precedent,regulatory guideline,or standard?standard?

ANSI/HPS N13.1-1999ANSI/HPS N13.1-1999There is a recent precedent in ANSI/HPS N13.1-1999 There is a recent precedent in ANSI/HPS N13.1-1999 Section 3.1.Section 3.1.

This ANSI Standard applies to emissions from nuclear This ANSI Standard applies to emissions from nuclear power plant facilities such as stacks, ducts and other exit power plant facilities such as stacks, ducts and other exit pathways.pathways.

Standard Conditions:Standard Conditions:““Used to convert air densities to a common basis. The Used to convert air densities to a common basis. The standard conditions adopted in this standard are a standard conditions adopted in this standard are a temperature of 25temperature of 25ooC and a pressure of 760 mm Hg.”C and a pressure of 760 mm Hg.”These are the reference conditions for Standard Ambient These are the reference conditions for Standard Ambient Temperature and Pressure.Temperature and Pressure.

Recommendations to the Recommendations to the RETS/REMP OrganizationRETS/REMP Organization

1.1. The RETS/REMP organization should consider its The RETS/REMP organization should consider its authority and responsibility to make an organizational authority and responsibility to make an organizational decision to recommend that all NPP members correct decision to recommend that all NPP members correct measured or calculated volumes that are determined measured or calculated volumes that are determined for air samples reported to any regulatory agency to a for air samples reported to any regulatory agency to a reference temperature and pressure definable by the reference temperature and pressure definable by the RETS/REMP organization.RETS/REMP organization.

Recommendations to the Recommendations to the RETS/REMP Organization (cont.)RETS/REMP Organization (cont.)

2.2. The RETS/REMP organization should determine and The RETS/REMP organization should determine and recommend an appropriate reasonable phase in time recommend an appropriate reasonable phase in time period of reporting corrected volumes in order to period of reporting corrected volumes in order to achieve uniformity of reported results that involve achieve uniformity of reported results that involve volume determinations.volume determinations.


3.3. The RETS/REMP organization should recommend the The RETS/REMP organization should recommend the selection of SATP in order to maintain consistency with selection of SATP in order to maintain consistency with ANSI/HPS N13.1-1999 that applies to the NPP ANSI/HPS N13.1-1999 that applies to the NPP community.community.


4.4. The RETS/REMP organization should notify the The RETS/REMP organization should notify the USNRC of the official position that the RETS/REMP USNRC of the official position that the RETS/REMP organization is taking and request that they provide organization is taking and request that they provide within 90 days a comment letter indicating any adverse within 90 days a comment letter indicating any adverse consequences they see in implementing the new consequences they see in implementing the new volume reporting strategy for purposes of achieving volume reporting strategy for purposes of achieving consistency among all NPP. Additionally, the USNRC consistency among all NPP. Additionally, the USNRC should comment as to whether any existing agency should comment as to whether any existing agency regulation, guideline or other document would prohibit regulation, guideline or other document would prohibit the implementation of reporting volumes corrected to the implementation of reporting volumes corrected to SATP (25SATP (25ooC, 1 atm) consistent with to that adopted by C, 1 atm) consistent with to that adopted by ANSI/HPS 13.1-1999 that is applicable to emissions ANSI/HPS 13.1-1999 that is applicable to emissions from NPP.from NPP.

ConclusionConclusion

The RETS/REMP organization has an opportunity to The RETS/REMP organization has an opportunity to take a bold step forward and make a significant take a bold step forward and make a significant contribution to the uniformity of reported data and to contribution to the uniformity of reported data and to implement a strategy that will provide for consistent implement a strategy that will provide for consistent reporting of sample volumes that are utilized to reporting of sample volumes that are utilized to determine compliance with emission limits, source, term determine compliance with emission limits, source, term calculations or for comparison with data from other NPP calculations or for comparison with data from other NPP worldwide.worldwide.

Documents

16 th Annual RETS/REMP Workshop 26-28 June 2006 Mashantucket, CT By Frank M. Gavila STP Has a Different Meaning to Different People