ML19345F592

Design Criteria for Effluent Monitoring,Sampling & Analysis

ML19345F592
Person / Time
Site:	Sequoyah
Issue date:	02/12/1981
From:	TENNESSEE VALLEY AUTHORITY
To:
Shared Package
ML19345F590	List: ML19345F589 ML19345F592
References
RTR-NUREG-0737, RTR-NUREG-737 NUDOCS 8102180478
Download: ML19345F592 (48)

Text

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V ENCLOSURE SEQUOYAH NUCLEAR PLANT DESIGN CRITERIA FOR EFFLUENT MONITORING, SAMPLING, AND ANALYSIS 9

81oenn y79,

As shown in Figures 1 and 2, part of the composite sample flows through the filter of the high range particulate radioactivity channel, through the adsorber of the high range iodine radioactivity channel, through the secondary iodine removal cartridge and then into the sa=ple space of the high range gross gaseous radioactivity channel, j- III. Grab Samples for Laboratory Analyses A. Grab Sample Requirements 1

The three channel high range effluent monitor provides real time detection of iodine radioactivity in filterable parti-culate form, other iodine radioactivity, and of gross gaseous radioactivity. The monitor shall also provide the following samples for laboratory analysis:

1. A particulate radioactivity grab sample is provided by the filter of the high range particulate radioactivity channel.

I

2. Iodine radioactivity grab samples are provided by the adsorber of the high range iodine radioactivity channel and by the secondary iodine removal cartridge.

3 A gross gaseous radioactivity grab sample is provided by the sampling arrange =ent shown in Figure 2.

B. Radiological Protection Design for Taking Grab Samples i The monitor shall be designed so that one person can remove i

- all four grab sa=ples, place them in shields provided by TVA, ready the =cnitor for renewal of operation with a new filter, new adsorber, new secondary cartridge and another gaseous grab sample container without incurring a dose equivalent greater than 0.3 rem to the whole body or 1.875 rem to any a

extremity.

i i The design must conform to these requirements when radiation fields corresponding to either of the following cases are present:

Case 1. ' Sa=ples are taken after a sampling time of 1.0 hour0 days <br />0 hours <br />0 weeks <br />0 months <br />.

Radicactivity inventories en the filter, adsorber, and secondary cartridge correspond to the existence for the 1.0 hour0 days <br />0 hours <br />0 weeks <br />0 months <br /> period of a sample air volu=e flow rate at its design value. The specific activities in the sample are initially as given in Tables 1 and 2. Credit can be taken for radio-active decay of both the activity in the sa=ple flow and in the collected samples during the sampling period.

Case 2. This case'is identical to Case 1 except that a sampling time of 12.0 hours0 days <br />0 hours <br />0 weeks <br />0 months <br /> shall be assumed.

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C. Acceptance Testing for Grab Satple Radiological Protection Design j The validity of the time and motion studies used in the dose equivalent evaluations shall .be demonstrated with one of the i .

conitors. The dose equivalent rates needed in these analyses-1

- 4-

~

. shall be empirically or analytically determined. In either 5 case, the dose equivalent rate deter =inations shall be t5oroughlydocumented. TVA approval of the dose equivalent rate evaluation procedures and acceptance of the documentation are required.

I IV. Module Equiptent

. A. Module I

1. Sample Uotake - The design features for the sample uptake are provided in the plant-specific requirements.  ;

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2. Sample Heater - The =cnitor shall contain a heater located 1

as shown sche atically as shown in Figure 1. The heater shall reduce the husidity of sample air at 100 percent ,

relative humidity and at a te=perature of 7007 --

to 1200F to a maximum of 50 percent relative humidity. The temperature of the heated air shall be co=patible with =enitor channel detector perforsance y

requirements.

l' 3 Sa:ple Division - It is necessary in most cases to divide the cocposite sample into' Sample A and Sample B as shown in Figure 1. When sample division is required, Sa=ple -

4 B shall be taken isokinetically from the co=posite sample.

i The air velocity in the Sample B uptake nozzle shall be autc=atically caintained within 20.0 percent of the air velocity at the location in the composite sa=ple piping

'i at which Sample B is taken.

I

'{ ,

_3 B. Module II Module II contains a sample air mover and a sample air volume flow rate measurement device. The air mover pump capacity shall be the design maximum value of Sample A air volume flow rate plus a suitable margin. When plant specific requirements specify that isokinetic sampling is to be automatically main-tained, the ratio of the sample air velocity in Module II to the velocity in the duct at the composite sample intakes shall be automatically maintained to within 20.0 percent of its correct value for isokinetic sampling.

C. Module III 4

1. High Range Particulate Radioactivity Channel - The high range particulate radioactivity channel shall employ a fixed filter.

With the noble gas concentrations in the sample as given l

, i -

in Table 2 and the radioiodine concentrations as given in l

l l

Table 1, at least 90 percent of the channel counting rate from the noble gases and the radioiodines after a filter collection time of 0.5 minutes shall be from I131 radio-activity. This requirement shall be met without any f

purging of the noble gases and regardless of the relative l

proportions of the different chemical forms of the iodine (i.e., elemental iodine, hypoiodous acid and methyl iodide). The determination that this requirement is met must take into account the counting rate from noble gases I  ;

i

in any part of the monitor sample space such as the sample

" piping, the space upstream, and downstream of the filter and the sa=ple spaces of the other two channels.

2. High Range Iodine Radioactivity Channel - With the noble gas concentrations in the sample air as given in Table 2, and the radioiodine concentrations as given in Table 1, at least 90 percent of the channel counting rate from noble gases and iodine radioactivity after an adsorber collection time of 0.5 minutes shall be from I131 radioactivity. This requirement shall be met without any purging of noble gases and regardless of the relative proportions of the different chemical forms of the iodine (i.e., elemental iodine, hypoiodous acid, and methyl iodide). The determination that this requirement is met must take into account the counting rate from noble gases in all parts of the monitor sample spaces including sample

. piping, the space upstream and downstream of the iodine 1

adsorber, the space occupied by the adsorber, and the sample spaces of the other two channels. It is believed that this requirement can be satisfied only by use of an adsorber material other than the usual TEDA impregnated charcoal since noble gases build up on the charcoal.

Also to meet the requirement, it will probably be necessary to minimize the sample space in the vicinity of the~adsorber cartridge.

3 High Range-Iodine Radioactivity Channel Adsorber Cartridge 1 ,

J 4

- 1

. j

, 4 l This section provides additional criteria which the

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cartridge selected for the high range iodine radioactivity I channel must satisfy.

At the end of a 12-hour sampling period, the adsorber cartridge iodine inventory after correction for 1131 decay shall include at least 80 percent as much I131 as that that has entered the sample space of the channel

< during the 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. Also, during the 12-hour sa=pling period, the efficiency of the cartridge for removing j sanple air iodine shall not have decreased by more than 1.0 percent and the iodine migration constant shall not >

have increased by more than 1.0 percent.

The iodine migration constant is that fraction of the iodine on the cartridge that escapes into the air downstream of the cartridge per unit time.

h The above requirements shall be satisfied for the

~

following assumptions and conditions:

a. Iodine concentrations are initially as given in Table 1 and, except for radiological decay, do not i

decrease during the 12-hour sampling period.

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b. Sample air volume flow rate is at the specified maximum value.

c. The iodine ~in the sample is a mixture of three 1 4 i

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l

8_

chemical for=s, any of which may vary from a negligible fraction to almost 100 percent of the total. The three chemical forms are : elemental iodine, hypoiodious acid, and methyl iodide.

d. The temperature of the sample air that enters the channel sample space has any value between 700F and 1200F and its relative humidity is as high as 95 percent.

4. Secondary Iodinn Removal Cartridge - The secondary iodine removal cartidge provides a means for determining what part of the nonfilterable iodine is not adsorbed on the adsorber cartridge of the high range iodine radioactivity channel. It also provides a measure of iodine migration from that cartridge.

The secondary iodina removal cartridge shall be identical i

to the adsorber cartridge of the high range iodine

i radioactivity monitor. It shall be located in series with and downstream of that cartridge, as shown in

! Figure 1.

5. Candidate Materials for Iodine Adsorber Cartridges -

Silver zeolite is often suggested as a replacement for the commonly used TEDA impregnated charcoal. However,

' the data of reference (1) indicate that it may be 5

-difficult- to satisfy the above requirements with this 1 -

L

i a .

material. Its efficiency for the removal of methyl iodide and hypoiodous acid may not be good enough. The  ;

I data of reference (1) do suggest that a silver impregnated silica gel adsorber may meet all requirements.

I

6. High Range Gross Gaseous Radioactivity Channel - The high ,L range gross gaseous radioactivity channel shall be  :

I operated in the gross mode so as to be able to detect i

) .!

} all of the noble gases in Table 2. Sufficient shielding  ;

r shall be used such that the channel counting rate from t iodine collected in the other two channels and in the f secondary iodine removal cartridge shall not contribute significantly to the channel counting' rate. Specifically,

' at least 99 percent of the channel counting rate at any  ;

I time frcm noble gases and iodine shall be from noble gas i

radioactivity. 'In the determination that this criterion f is met, the following shall be assumed:

I (a) Noble gas concentrations are initially (time of,  !

it reactor shutdown) as given in Table 2 and at any- f time thereafter are determined by application to 1

the initial values of corrections for radioactive decay.

-(b) Iodine inventory on the filter of the high range ,

, particulate radioactivity' channel corresponds to

. continuous ~ sampling of air at initial concentrations

• ~

of filterable-particulates corresponding to values.

in Table 1. with rua filter change.- Corrections for

't.

, , - -- , . . , , - , ,- - . ~ ,

radioactiva decay are made in both the sample air concentrations and in the inventory on the filter.

(c) Iodine inventory on the adsorber cartridge of the high range iodine radicactivity channel corresponds to continuous sampling of air at initial concentrations of non-filterable iodine corresponding i

to values in Table 1 with no adsorber change.

Corrections for radioactive decay are made in both the sample air concentrations and in the inventory i on the adsorber.

(d) Iodine inventory on the secondary iodine removal cartridge is obtained by multiplying the inventory on the channel adsorber cartridge by the factor, 1.0 less minimum efficiency for collection of iodine on the channel adsorber-cartridge.

!l

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V. Channel External Background Considerations lt For any of the three channels, the counting rate corresponding to the nuclide concentrations that are to be evaluated are

l. '

determined by subtracting from the total counting rate, Rt , a background counting rate, Rb , that includes external background

! and instrument background.

l l

l The external background for any of the three high range channels I .

i, includes any radiation that reaches the channel detector from

. radioactivity in the sample spaces of the other two channels and l

from iodine radioactivity on the secondary adsorber. Each channel detector shall be shielded fron radionuclides in the sample space of the other two channels and frem iodine radioactivity of the secondary adsorber cartridge such that the contribution to the channel external background fec: these sources is negligible in comparison with the counting, rate from radioactivity in the channel sa:ple space corresponding to the lower end of the i

specified channel range. For purposes of determining the required shielding, the following sources in the sa ple spaces of the three channels shall be assumed.

A. The filter of the high range particulate radioacti) Aty channel has been collecting particulate radicactivity at the concentrations given in Table 1 with credit for radioactive decay for 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. ,

B. The adsorber of the high range iodine radioactivity channel' has been collecting iodine radioactivity at the concentrations given in Table 1 for 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> with credit for radioactive I '

decay during the collection.

C. The secondary iodine adsorber has been collecting iodine

. Adioactivity at 20 percent of the concentrations given in Table 1 for 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> with credit for radioactive decay during collection.

D. The sample spaces of all three channels contain noble gas-radioactivity at the concentrations given-in Table 2.

i i

VI. Data Output of High Range Particulate Radioactivity Channel and High Eange Icdine Radioactivity Channel

' The data output of high range particulate radioactivity channels and high ran6e iodine radioactivity channels shall be provided 4 in microcuries of I131 per standard cubic centimeter, CI131' calculated as follows:

For the calculation of CI131, knowledge of the time that the filter or iodine adsorber has been on-line (i.e., collecting) is necessary. Therefore, each channel shall have its own clock or be synchronized to another clcck. A simple operator action shall tell the data handling device (e.g., a micro-processor) when the t lter or adsorber is beginning to collect.

The device reads the clock at that moment in order to establish the time, to, which is the first of two times it requires in order 4

to calculate a collection time for the first calculation of CI131 The referenced operator. action shall be available at both the =onitor location and in the main control room.

I i The concentration, CI131, shall be calculated from rate of change of counting rate measurements. A total counting rate, Rt , shall be measured during the last 5.0 seconds of each minute.

l The end of the minute.shall be considered as the time of the count. The total background counting rate, Rb', consisting of of the external background counting rate and 'the electronic or-intrinsic background counting rate, shall be subtracted to yield,.

RI131, the counting rate due to I131.'

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- The external background counting rate for either channel includes any contribution from inadequately shielded radioactivity in the sample spaces of the other two high range channels.

A method shall be provided to continuously assess the background countins rate, R b. One acceptable method is the use of three analyzer channels instead of one. The middle channel would count an I131 peak. The average counting rate from the two adjacent channels might be a good estimate of Rb . Values of RI131 less than X, standard deviations of the background counting rate, R b , shall be set equal to 0.0. The rate of change of RI131, i.e., 4RI131

( o t)a is calculated from the expression:

$EI131 ._,

IEI131)tn - (RI131)tn - I d D)n-( 4 t) , (at)n

- - 3n_cgg)n,g a where the subscripted time interval is the interval over which the rate of change is calculated.

The first value of the rate of change is calculated at'tt the end of the first minute at which a value of RI131 that has not been set equal to 0.0 is available. This first rate of change value is calculated as follows:

SE I131 = (RI131} 1 - 0 (4t)! t;-(4t)3,t; D1~Do A new rate of change calculation is performed at the end of each I

j -,

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. -14 minute if the measurements made during the last five seconds of the minute produca a value of RI131 that is not set equal to 0.0.

To determine each value of

l. 1131

( 4 t), t,- ( 4 t),, t, the time interval, ( 4 t)n must first be selected. This selection shall be made as follows:

First compare the quantities:

( I131)tn ( I131}t n .0167 If (RI131)t n I131 k , .0167 < Xgr(RI131)t h .01M i

compare -(RI131)k and (R I131 tn .0333-If (RI131)tn -C I131)t n .0333 M II"I131)t J ~

n

.0333 compare (RI131)t and (RI131}t n

.0500 n-

.i

.. l

Repeat this procedure with the trial values of ( 4 t)n increasing by .0167 with each trial antil a value is found for which 4

(RI131)tn - (RI131}t1 - (4t)n 2 X2 C (RI131)tn - (4t)n 1

If there exists no value of ( 4 t)n such that this relationship is satisfied, set ( 4 t)n = tn -to i

After (4t)n has been determined, calculate the quantity dE I131

( d t) t - ( 4 t) ,t ,

va ue of I131)tn - C S tIn , tn 4

I from the rate of change determinations using the following assumptions and data:

1 i . -

l A. C shall be assumed to have a

! -I131- t n - ( 4 t)n, t n constant value over the time interval, t n ~( n, t n

l B. Sample air volu=e flow rates shall be averaged over time increments not greater than 10 minutes. Therefore, the.

sample air volume flow rate used will generally not be.a y single average over ( d t)n. In this way different rates i

1 . ,

1^

of collection on the filter are taken into account.

C. An input value of filter or adsorber iodine removal efficiency shall be used.

D. An input value which relates R and si r uries f D31 I131 on the filter or adsorber for an assumed iodine chemical i

species distribution shall be used.

When hard copy printout is required, for each calculation I '

I131_ tn ~ I d "I n' tn there shall be a printout (preferably on a single line) of the following:

1.

t n - ( 4 t)n

2. t n

. F l 3 c

_ I131; t n ~ ( d D}n, t, VII. Calculations of I131 Release Rates I131 concentrations as determined with the high range particulate radioactivity channel and iodine radioactivity channel are combined with measured exhaust duct air volume flow rates to determine I131 release rates. The release rate calculations are made at a frequency input by the operator. The capability for caking these calculations as frequently as once per minute shall be provided.

I -

Note that the ( 4 t)n, used in the evaluation of I131 concentrations, will usually overlap ( 4 t)n-1 Only when the filter or adsorber has not been collecting very long or when the iodine concentration is increasing rapidly will this overlap not occur.

1 l i Whenever there is more than one calculated I131 concentratien for a part of the time interval over which I131 release rates are to be calculated, the highest calculated I131 concentration shall be used for that part of the interval.

• lIII . Data Output of High Range Gross Gaseous Radioactivity Channel The data output of high range gross gaseous radioactivity ,

channels shall be provided in total microcuries per standard cubic centimeter, CGGR, calculated as follows.

Channel total counting rates, R t, shall be obtained no less I

frequently than at ten second intervals. From the six or more values per minute, a one minute average shall be calculated at

! the end of each minute.

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4 The total background counting rate, Rb , consisting of the external background counting rate and the electron 12 or intrinsic background l

I counting rate, shall be subtracted to yield RGGR, the gross gaseous radioactivity counting rate. The external background counting rate j

includes any contribution from inadequately shielded radioactivity in the sample spaces of the other two monitor channels.

L -

Instrumentation shall be provided to continuously assess the the background counting rate, Rb , no less frequently than at ten second intervals. The measured value of Rb may be subtracted from the concurrently measured value of Rt to obtain RGGR*

Alternatively, one minute averages of Rb may be subtracted from the one minute averages of R t-Values of RGGR shall be converted co values of CGGR with inpat time dependent factors as described below.

Each channel shall have its own clock or be synchronized to another clock. The data handling device for each channel shall store at least six sets of thirty time dependent factors for converting channel net counting rate, RGGR, to radioactivity concentration. For each set, the thirty conversion factors shall be assigned to thirty consecutive time intervals. The first time interval begins at to , which might correspond to the start of an I

accident. At any time the operator shall have the capability both at the monitor location and in the main control room to inform the channel data handler of the current time with respect to to , and which one.of the six sets of conversion factors to use. For example, the operator may inform the channel that the current time is thirty. minutes after ot and that conversion factor Set 3 is to be used. The channel data handler then has sufficient information to convert net-cour. ling rates to gross gaseous radioactivity concentrations. The operator shall also be able to change any' or all of the factors in a set by simply identifying 1 ,

the set, the number of the factor to be changed, and the new factor. The operator shall also have the capability to alter the thirty time intervals.

Normally, one minute averages of CGGR shall be calculated; however, the operator shall have the option of selecting a time interval longer than one minute over which averages are to be I

taken.

When hard copy printout is required, for each calculation of CGGR, there shall be a printout (preferably on a single line) of the following:

time (end of time-t o Conversion factor , CGGR minute for which (cpm to microcuries, average CGGR is per standard determined) cubic centimeter) i ~

The last 60 values for this printout shall always be retained for printout en demand.

IX. Calculation of Gross Gaseous Radioactivity Release Rates Gross gaseous radioactivity concentrations, CGGR, as determined from measurements with-high range gross gaseous radioactivity channels, are combined with measured exhaust duct air volume flow rates to determine. gross gaseous radioactivity release rates.

The release rate calculations are made at a frequency input by.

the operator. The capability for making these calculations as I w

} . .

frequently as once per minute shall be provided.

X. One Channel High Range Effluent Monitor For some applications the high range effluent monitor has only a high range gross gaseous radioactivity channel. The one channel monitor has Module I and Module IV as shown in Figures 1 and 2, respectively. All requirements given above for instrumentation f

in Module I and Module IV for a three-channel high range effluent monitor are applicable to the one channel high range effluent I monitor.

XI. Sensitivity and Range High Range Gross Gaseous Radioactivity Channel The range of the high range gross gaseous radioactivity channel is bounded by t2: channel sensitivity, CGGR-L, the lowest concentration of gross gaseous radioactivity that is detectable with the channel, and by CGGR-H, the highest concentration that is detectable, within required accuracy, by the instrument. The I

low end of the channel rar.ge must overlap the upper end of the

, range of the low range gross gaseous radioactivity channel of the currently installed monitor by at least one decade. The upper end of the channel range shall be as given in Reference 2.

CGGR-H shall be the sum of the concentrations of all noble gas nuclides with an entry in Table 2 and relative nuclide concentrations shall be as in Table 2.

The specified lower end' of the range shall be satisfied with 4

l- '

j ,

. _ _ = .-. . - _. . . . - -

. a value of CGGR-L consisting of any of the following:

1. The sum of all noble gas nuclides with an entry in Table 2 in the relative nuclide concentrations as in Table 2.

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2. Xe133 only.

3 Kr85 only.

XII. High Range Particulate Radioactivity Channel and High Range Iodine Radioactivity Channel The range of the high range particulate radioactivity channel and of the high range iodine radioactivity channel shall be similarly 4 specified. The icw end of the range shall be specified as:

)

CI131-L; 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> collection; mini =um sample air volume flow rate.

The high end of the range shall be specified as:

t CI131-H; 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> collection; =axi=um sample air volume flow rate.

I The concentrations, CIj31_L and C1131-H, are I-131 concentrations at the beginning of the 12-hour collection period. In determining that a channel has the required range, a correction shall be made during the 12-hour collection period for. radio-active decay of I131 in the sample concentration and in the inventory on the collecting media. The low end of channel range shall overlap the upper end of channel range of the icw range currently installed scnitor by at least one' decade. .The

l concentration, CI131-H shall be as given in Reference 2.

The above channel range requirements for I131 shall be met with the sample air also containing, at the beginning of the 12 hour1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> sampling period, the other iodine nuclides in the concentrations given in Table 1. Corrections for radioactive decay during the 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> shall be =ade. The corrections apply to both concentrations in the cample air and to inventories on the collecting media.

XIII. Low Range Monitor Isolation The low range monitors shall be isolated on an alarm signal from the high range particulate radioactivity channel. The isolation shall also occur on an alarm signal from the high range iodine radioactivity channel. The isolation capability is necessary so that the collecting media of the low range monitors will not become too radioactive to allow the monitor to be returned to normal operation when sample radioactivity I

concentrations are reduced to within the monitor design range.

XIV. Monitor Sample Space Leakage There shall be no significant leakage of room air into the monitor sample space or outleakage of sample air from the monitor sample space. Testing shall ensure that inleakage will never exceed

.002 cfm and that outleakage will never exceed .002 cfm. -

XV. Radiation Damage The absorbed dose (in rads) to all monitor components for a 1.0 i

l b

t year operating period shall be calculated. For these calculations, the maximum sample air volume flow rates shall be assumed. Radioactivity concentrations in the sample shall be assumed to initially consist of the sum of the following:

1. cGGR-H

2. cI131-H 3 CI131, CI133, CI134, and CI135 values in table 1 reduced by the factor, C I131-H/ 2 j (1.0 x 10 )

Subsequently, credit for radioactive decay in sample air con-centrations anc in radioactivity inventories on collecting media shall be taken. Collecting media shall be assumed to collect nuclides for 7.0 day intervals before replacement. The absorber dose contribution from external background shall be specified i

by TVA.

i The monitors shall continue t's operate within specifications l after subjected to absorbed doses as high as those calculated.

l All component materials not known to be unaffected by subjection

> i to the calculated absorbed doses shall be tested.

XVI. Alternative Designs Variations to the specified monitor configuration and mode of operation shall be considered provided all specified performance l- w

i requirements and capabilities are available with the proposed altern'atives.

XVII. Supplier Capabilities In addition to the usual capabilities required of a supplier

, of radioactivity monitoring instrumentation, for satisfactory performance of a contract award for the specified instrumentation, a supplier must possess or have access to the capability for evaluating absorbed doses and dose equivalents from specified source terms. Vendor capabilities in this respect will be evaluated before award of contract.

XVIII. Sampling Design Criteria for the numbers of and location of sample intakes,are provided in PART THREE. Sample intake nozzle inside diameters shall not be less than 0.25 inch. The design of sa=ple piping from the points or sample intake to the monitor detection i

assemblies shall conform to guidance provided in reference 3.

Conformance with reference 3 requires that the monitor detection be located reasonably close to the' sample intake points. Monitor detection assembly locations are considered in PART TWO.

i

/ To Exhaust Doct N

To Exhaust Duct l -

I . _ _ .{

MODULE I H l l l

E

! Sample Flow Air  !

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.._.. C.oingos.Lle A _

Sample T A Measurement Mover l I l E

a l 1 l -.

MODULE II j .- . - - - -

l E u, _

g i

• Secondary gg ygg Particulate Iodine IUdI"U Itadioactivi ty -

Radioactivity --

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Channel Cliannel Ca tr cc (S e Fig. 2)

Dhaust -

N0DULE Ill l Unct

__ -- -- - - .-. -_ . - -l e

FIGURE 1. HIGil-RANGE GASEOUS RADI0 ACTIVITY MONITOR J s

'1 .

l  :

1

~~

l I

Gross

!N Gaseous ~~

Flow Air v Radioactivity Measurement . Mover g

Channel ' l l

M @* D--M l A A I

l I

MODULE IV Code: A = quick disconnects B = Sample container 4

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FIGURE 2. MODULE IV 0F llIGil-RANGE GASE0US RADI0 ACTIVITY NONITOR

TABLE 1 Design Basis Iodine ?.adicactitity .Cencentratiens (In gnsecus effluents downstrean of a fi' tratien-adsceptien unit)

Micrc:uries ?er Standard Cu:ic Centineter I131 1.cco+2' I132 1.224+2 I133 1 999+2 I134 2 354+2 1135 1.842+2

. Gr--* eer Cubic Centineter I129 1.718-8#

.e x

• y + x = y x 10

-x Py - x = y x 10 G

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p 4

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1 1

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-.___ . .- . . - . ._.. . . ~ . _-

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S TABLE 2 Noble Gas Concentrations for Range Specification of High Range Gross Radicactivity Channels

• Ahat can Monitor Discharges fren the Pri=ary Containment Microcuries cer Standard Cubic Centi =eter Kr 83= 2.079+03' Kr 85= 4.672+03 Kr 85 1.822+02 Kr 87 8.075+03 Kr 88 1.272+04

, Xe 131m - 1.638+02 Xe 133m 6.699+02 Xe 133 2 336+04 Xe 135m 3 913+03 Xe 135 2.262-04 Xe 138 2.091+04 Total 1.000+05 i

' x

'y + x = y x 10 i -- ,

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5 e e

~9 ._y. ,,y.ye.., ,y 4. - -- , .,.y . ., .,g*-- =

9 - 9 y..~ w. y

r REFEFINCES

1. NUEEG/CR-0314 EN1.-NUREG-50351 FI - in Air Sanpling Syste: For Evaluating the . Thyroid Dese Cc==it=ent Due to Fissten Products Released frc= Reacter Contain=ent.

2. Proposed Revisien 2 to Regulatory Guide 1 97, Instru=entation for Light 'n'ater-Cooled Nuclear Power Plants to Assess Plant and Environs Conditions During and Following an Accident, Dece=ber 1979 e

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PART Tt30 I. High Range Monitors The range provided by each normal range shield building vent monitor shall"be extended by providing two 3-channel high-range effluent monitors, as defined in PART ONE. The range provided by the auxiliary building exhaust monitor shall be extended by providing one 3-channel high-range effluent monitor, as defined in PART ONE. The range provided by the two condenser vacuum pump exhaust monitors shall be extended by providing one 1-channel high-range effluent monitor, as defined in PART ONE.

II. Specific Requirements for High-Range Monitors A. Shield Building Vent Monitors (4 per plant required)

1. Range for Gross Gaseous Radioactivity Channel C

GGR-L = 1.7 x 10 -2 pCi/cc -

C * * "

GGR-H

/

2. Range for Particulate Radioactivity Channel Il l C I1314 = 1.0 x 10 -7 gi/cc i

sample intake points.

B. Auxiliary Building Exhaust ~ Monitor'(1 per plant)

1. Range for Gross Gaseous Radioactivity Channel 1

C = 1.7 x 10~ 'pCi/cc i' l N o

^

GGR-L C

GGR-H *

/"

i 2 .- Range for Particulate Radicactivity Channel Same as for shield building vent monitors.

3 Range for Iodine Radioactivity Channel i

Same as for shield building vent monitors.

4. Sample Intakes The locations of and the numbers of sample intakes for Module I shall be determined in accordance with the criteria of PART THREE. The sample intake array shall be added to the duct section that is being procured and which, until this addition, was specified to contain airflow conditioning sections, arrays for pressure sensing and an array of sample intakes for the normal range monitor. Isokinetic sampling and automatic adjustment to maintain sampling as the duct air volute flow i rate changes shall be provided. The velocity of sample intake air shall be within 20.0 percent of the duct air velocity at the sample intake points.

C. Condenser Vacuum Pump Exhaust Monitor (1 per unit)

1. Range for Gross Gaseous Radioactivity' Channel 9

L.

= 3 7 x 10 juci/cc C ggg, C

GGR-H *

/" "

2. Sample Intakes ll The locations of and the numbers of sample intakes for Module I shall be determined in accordance with the triteria of PART THREE. Representative sampling (and isokinetic sampling) are 4

not required.

l III. Locations of Monitor Detection Instrumentation Monitor detection assemblies shall be close enough to the sa=ple intake

< points so that there is no substantial loss of particulates and iodine not in filterable particulate form on the piping walls. Accessibility of the monitor detection assemblies during accident conditions is another consideration. Unless a more suitable location can be found, the high-range monitor for the auxiliary building vent may be located near the present normal range monitor location.

> For the condenser vacuum pump high-range monitor, the distance of the detection assembly from the sample intake points is not an important consideration. The detection assembly may be located near that of the nor=al range monitor.

IV. Calibration i

L l

Using proceduras ace:ptable to TVA, the manufccturce shall psrform a complete primary calibration that demonstrates the monitors meet all performance specifications including sensitivity and range requirements. The procedures shall be approved by TVA before the official primary calibrations are performed. TVA shall witness the primary calibrations unless an official TVA declination to do so is provided. The manufacturer shall develop methods for secondary calibrations at the power plant and shall provide to TVA any needed special sources and equipment that are not readily available from commercial outlets.

V. Check Sources Each channel shall be provided with a check source operable both at the monitor r6ssembly and from a main control room panel to verify channel operability. ,

VI. Channel Alarms i,

Each channel shall have visual alarm in the main control room for low I radioactivity level (i.e., equipment malfunction), high radioactivity level and high-high radioactivity level. For each-monitor, a low sample B air volume flow rate visual alarm shall also be provided in the main control room.

Each condition that is visually alarmed shall also be annunciated by a common audio annunciator supplied by the manufacturer or, at TVA's option, by another main control room annunciator.

l 1 l ,

1

VII. Indication and Recording For each high-range particulate radioactivity channel and each j

high-range iodine radioactivity channel, channel rate of change of I131 cpm or microcuries of I131 per standard cubic centimeter shall be indicated in the main control room. For each high range gross gaseous j radioactivity channel, net cpm, i.e., Rggg, or microcuries per standard cubic centimeter shall be indicated in the main control room.

'I Total plant release rate of I131 in filterable particulate form, total plant release rate of nonfilterable I131 and total plant release rate of gross gaseous radioactivity shall be calculated by two qualified trained devices and recorded by qualified trained recorders.

Since it is anticipated that, in the near future ~, the plant will have a radiation monitoring system (RMS) computer, all channels s, hall have output that is acceptable to most computers commonly in use for this purpose. It is also desirable that the qualified trained devices that calculate release rates also have the capability of providing these release rates to the future RMS computer.

I i VIII. Other Design Criteria

( The high-range monitors must meet any requirements of reference 2 of PART ONE for instrumentation type E that have not been specifically defined in PARTS ONE, TWO, and THREE of these criteria.

1'

PART THREE 1

, 1.0 GENERAL Part three provides criteria for the determination of the cross-sectional area in each path to be monitored at which monitor samples are to be extracted. Also developed in this part is the relationship between the minimum number of points in a gaseous effluent duct cross-sectional area at which samples are to be extracted and the i

distances of the cross-sectional area from upstream and downstream 1

sources of flow disturbances within the duct.

2.0 EFFLUENT PATH CROSS-SECTIONAL AREA FOR EXTRACTION OF MONITOR SAMPLE This section provides guidance for determining for each monitored duct the location of the duct cross section at which sample poi,nts are to be 2

positioned.

If a choice can be made between sampling from a vertical or horizontal run of duct, the vertical run should be favored. Stratification of

i particles due to gravity settling may thus be avoided.

?

i '

j Sampling from a duct cross section near the release point to the atmosphere is preferred.

When practical, the distance of the cross-sectional area for sampling downstream from any transition, elbow, or other source of flow l

l disturbance should be at least eight (8) duct equivalent diameters for l .

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r circular ducts and at least eight (8) duut cquivalent diamsters for rectangular ducts. An equivalent diameter for a rectangular dact is defined in Section 3.1. Also, when practical, the distance of the crossisectional area to any downstream source of flow disturbance should be at least two (2) duct diaceters or equivalent dia:eters.

These mini =us upstream and downstream distances are distances along which the air flow is essentially unobstructed; therefore, the actual distances should be increased by the lengths of any flow conditioning I

duct sections since these sections retard mixing within the duct.

Shorter distances may be used if the penalty in the for= of an increased nu=ber of required sample points is acceptable. Except in the case of s= aller ducts, the mini =um upstream distance of unobstructed flow may be reduced to as few as two (2) diameters or equivalent diameters and the minimum downstream distance of unobstructed flow to as little as one-half duct diameter or equivalent diameter. ,

The relationship between the unobstructed distances from sa=pling cross-sectional area to sources of flow disturbances and the mini =um nu=ber of sample points are provided below in Section 3.1. Section 3.1 also points out that for small ducts (i.e., ducts less than 2.0 feet in

? diameter or equivalent diameter), upstream unobstructed distances less than five (5) duct diameters or equivalent diameters and downstream unobstructed distances less than two (2) duct diameters or equivalent i diameters should be avoided if at all practical. For very small ducts (i.e., less than 1.0 feet in diameter or equivalent diameter), an unquestionable design might not be achievable if these minimum distances are not provided since use of a sufficient number of sample i ,

i

i nozzles to compsnsato for insufficient distences would unacceptably 1

obstruct duct air flow.

l 1

3.0 NIRGER AND LOCATIONS OF SAMPLE EXTRACTION POINTS i

31 NUMBER OF SAMPLE POINTS 3

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' A sufficient number of sample points to obtain reasonably 1

, representative sampling must be used. Representative sampling is defined in Section 4.1. <

This section gives a procedure for determining the minimum number of sample points that are required to obtain a representative sample from a gaseous effluent duct cross section. The procedure is as follows:

1. For a circular duct with a diameter 2.0 feet or greater and for which campling is to be done at a duct cross-sectional i

area that is at least eight duct diameters of unobstructed

!i flow downstream and two diameters of unobstructed flow

i upstream of any flow disturbances. The minimun number of I sample points is twelve (12).

2. If the design in 1 above for sampling a circular duct with a diameter 2.0 feet or greater is not practical, select a duct cross-sectional area that is at least two (2) duct diameters of unobstructed flow downstream and at least one-half (0.5)

. duct diameter upstream of. any flow disturbances and use Figure -

, a w

.a ,

~

1 to obtain the mini =um nu=ber of sample points. It is obvious frcm this figure that the shorter the distance fec=

the sa:ple cross-sectional area to any flew disturbance, the greater is the penalty in the fccm of an increased nu ber of required sa=ple points. To use Figure 1, first deter =ine the unobstructed distances from the chosen sampling cross section to the nearest upstreas and downstreas disturbances. From the figure, determine the corresponding nu=ber of sa:ple points for each of these distances. Select the higher of the two numbers or a greater value such that the nu=ber of required sa:ple points is a =ultiple of fcur (t). Use of cnly

=ultiples of four (4) simplifies the arrange:cnt of the sample no::les.

3 For a rectangular duet use the following equation provided in F.eference 5 to define en equivalent dia eter: -

equivalent diameter = 2 (length)(width) length + width 4 If the equivalent dia eter is 2.0 feet er greater, follow the i procedures in 1 and 2 above with the ter:s " circular" and "dia:eter" replaced by the terms " rectangular" and " equivalent dia eter," respectively.

5. For a circular duct with dia:eter less than 2.0 feet, the unobstructed distance of the sa:pling cross-sectional area downstream of any air ficw disturbances should be a =inisn= of 1

fiva (5) and prarcrably t;n (10) or mora duct diamatcrs. Tha unobstructed distance between the sampling cross-sectional area and any downstream flow disturbance should be a minimum of two (2) duct diameters. When these conditions of minimum distances from sampling .ross-sectional area to upstream and downstream disturbances are met, the mini =um number of sample points within the sampling cross-sectional area as a function of the duct diameter, d, is as follows:

i Diameter, d Minimum Number (inches) of Sample Points ds6 1 6 < d 5 12 2 12 < d 5 18 3 18 <; d s 24 4

6. For a circular duct with a diameter less than 2.0 feet, considerable design effort and expense to meet th,,e requirements that allet* use of the procedure in 5 above are justified. Particularly in the case of the smaller ducts (say less than 1.0 foot in diameter or equivalent diameter), there might be no unquestionably acceptable alternatives. If the

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design does not allow the use of 5 above, use Figure 1 as

' directed in 2 above for large circular ducts. Multiply the

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number of points obtained by the factor .67 to obtain the required minimum number. Increase the minimum number to a multiple of four (4). Particularly in the case of the smaller ducts, the number of required sample nos:les determined with this procedure may result in unsatisfactory obstruction to air flow in the duct. In such a case, the number of sample points i ,

cmploycd would b2 sst by tha maximum obstruction to air flow

, in the duct that could be tolerated. The acceptability of the resulting design might not be unquestionable.

7. For a rectangular duct with equivalent diameter less than 2.0 feet, follow the procedures in 5 and 6 above with the terms

" circular" and " diameter" replaced by the terms " rectangular" and " equivalent diameter," respectively.

Other procedures or criteria for determining the number of required sample points have been proposed. One procedure begins with the defining of a cross-sectional area unit. The procedure than states that one (1) sample point per cross-sectional area unit is required. The cross-sectional area unit is obtained by some form of extrapolation of the relationships in Section A3 of Reference 5.2. With this procedure, the number of required sample ,

points is directly proportional to the duct cross-sectional area.

The formulation of this method is based on the view that obtaining a statistically valid sample requires that the total sample be equal to or greater than some fixed fraction of the total duct air i

flow regardless of how large the duct is. This view is not valid.

. If a total sample air volume flow rate from a small duct produces measurements with acceptable statistics, an equal total sample air volume flow rate from a large duct will generally produce measurements with equally acceptable statistics. The reason for any increase in the required number of sample points is not to improve the statistics of the monitoring data but to make reasonably certain that the total sample is sufficiently l

rsprassntativa. In most cassa there is no reason to bslieve that the use of the same number of sample points (i.e., the same total sample air volume flow rate) in a large duct as in a small duct will result in a less representative sample for the large duct, provided the sample duct cross-sectional areas in both cases are sufficient numbers of duct diameters or equivalent diameters from duct flow disturbances.

Use of a larger number of sample points than that determined necessary from steps 1 through 7 above will provide acceptable sampling, provided it does not drastically complicate the design of a system which will have acceptably small losses of particulates and iodine in the sampling lines. However, unnecessary penalties, such as in increased sample air mover capacity requirements, are incurred. Therefore, acceptance of a standard design which employs more sample nozzles than needed may be more economical than purchase of a custom design which employs the minimum needed number of sample nozzles.

3.2 ARRANGENENT OF SAMPLE POINTS i For circular ducts, arrange the sample points as follows:

1. If a minimum of one (1) sample point is required'and only one'(1) i

-is to be used, locate the sample point at the centroid of the duct cross-sectional area.

2. If a minimum of two or three points are required and two or three-t 9

are to ba used, divide the cross-sactional area into a lika number of areas and locate one sample point at the centroid of each area.

3 -If four (4) or more points are to be used, locate the points on Tt least two (2) diameters in accordance with Figure 2 and Table 1.

I The diameters must divide the cross section into equal parts. If many points are needed, they should be located on more than two (2) diameters in order to provide a more representative sample.

For example, it would be preferable to locate sixteen (16) sample points on four (4) diameters rather than on two (2) diameters.

4. For rectangular ducts, divide the duct cross section into as many equal rectangular areas as the number of sample points to be used.

The ratio of the length to the width of the elemental areas must be between 1.0 and 2.0. Locate one point at the centroid of each areas as illustrated in Figure 3 ,

S. For any duct, a sample point should never be within 1.0 inch of the duct wall.

I 4.0 DEFINITIONS 4.1 REPRESENTATIVE SAMPLING A sample extracted from a gaseous effluent duct is representative of the effluent passing through the duct cross-sectional area in ,

vhich the one or more sample extraction points are located if its composition is identical to the average composition of the 1

.l m m -m -vem +- em,

w. w- , w -- vm-- m

efflusnt passing through the cross-ssotional area. The aspects F of the composition for which the equality must exist are the following:

1. Specific activity of each radionuclide, in microcuries per l standard cubic foot.

2. Sizes, densities, and numbers of particles per standard cubic l

. foot.

3

5.0 REFERENCES

1 5.1 Title 40-Protection of Environment, Code of Federal Regulations, Part 60, APPENDIX A. July 1,1977, edition.

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FIGURE 1. Minu=um nu=ber of sample points.

Nu=ber of Duct Diameters Upstream Y (Distance A) 0.5 1.0 .. , 1.5 2.0 2.5 0 .  ! ., t  !*  !  ! l . I S .

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Figure 2. Cross secticn of circular duct divided into 12 equal areas, showing location of sa ;1e points at_e_entroid of each area.

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i Fii!;ure 3 Crcss section of rectangular duct divided into 12 equal-

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areas, with sample points at centroid of each area.

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Table 1. Location of sanple points in circular stacks (Percent of

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duct dia:eter fro: inside walls to sa:ple point)

Sa:ple Point Nu=ber Number of sacole coints on a diameter en a Diameter; 2 l4 l6 l8 l10l12 14 l 16 18 l 20 22 ,24 i 1 14.6l 6.7 4.4 3.3 2.5 2.1 1.S 1.6 1.4 1.3 1.1 1.1 2 S5.4 25.0 14.7 10.5 8.2 6.7 5.7 4.9 4.4 3.9 3.5 3.2 .

3 75.0 29.5 19.4 14.5 11.E 9.'9 8.5 7.5 6.7 6.0 5.5 4 93.2 70.5 32.3 22.6 17.7 14.6 12.5 10.9 9.7 a.7 7.9 5 85.3 67.7 24.2 25.0 20.1 16.9 14.6 12.9 11.6 10.5 6 55.5 E3.5 65.3 35.5 25.9 22.0 18.3 16.5 14.6 13.2 7 89.5 77.4 64.5 35.5 23.3 23.6 20.4 18.0 16.1 8 - $5.7 E5.4 75.0 53.4 37.5 29.6 25.0 21.E 19.4 9 91.S 22.3 73.1 62.5 33.2 33.6 25.1 23.0 10 S7.5 E3.2 79.9 71.7 61.E 33.3 31.5 27.2*

11 ' 93.3 85.4 73.0 70.4 61.2 39.3 32.3 12 . S7.9 S3.1 83.1 76.4 69'.4 63.7 39.8

.13 S;.3 87.5 81.2 75.0 E3.5 60.2 14 53.2 91.5 E5.4 79.6 73.9 57.7 15 95.1 89.1 33.5 73.2 72.8 15 S3.4' 92.5 E7.1 S2.0 77.0 17 95.6 90.3 25.4 E0.6 15 . .S3.6 53.3 E3.4 E3.9 19 S5.1 91.3 25.C 23 $3.7 91.0 29.5 21 S5.5 S2.1

'22 -

- 93.9 S1.5 23

$ 5.3 24 S3.9 l

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