ML20049H511
| ML20049H511 | |
| Person / Time | |
|---|---|
| Site: | LaSalle  |
| Issue date: | 02/24/1982 |
| From: | Schroeder C COMMONWEALTH EDISON CO. |
| To: | Schwencer A Office of Nuclear Reactor Regulation |
| References | |
| 3525N, NUDOCS 8203030230 | |
| Download: ML20049H511 (13) | |
Text
e.
Commomwealth Edison O
one First NItional Pitza, Chictgo. Ilhnois O
Address Reply to: Post Office Box 767 Chicago Illinois 60690 February 24, 1982 N
N D
Mr. A. Schwencer, Chief O. ~ <>C E
Licensing Branch #2 l g/!?t,,,7/?p !h@.
S Division of Licensing,
f U.
S., Nuclear Regulatory Commission c, j
/pg e
Washington, DC 20555
'*<t
[
Subject:
LaSalle County Station Uni l~ a p"6 Response to Informal Question CM NRC Docket Nos. 50-373 and 50-374
Dear Mr. Schwencer:
The purpose o f this letter is to provide you with Common-wealth Edison Company's response to' informal-questions on the Of f-Site Dose Calculation Manual (ODCM).
These questions were previously discussed with Mr. A. Bournia of your staff.
Enclosed please find:
1.
NRC Questions on LaSalle County Station ODCM, Section 8.
2.
Commonwealth Edison Company's response to the NRC questions.
3.
A revised copy of the LaSalle County Station ODCM, Section 8.
The revised ODCM Section 8 will also be transmitted to you.
as part o f a routine document update for the controlled copy o f the ODCM issued to your o f fice.
If there are any further questions in this regard, please contact this office.
Very truly yours,
~ 1.]n+ l9n C. W.
Schroeder Of Nuclear Licensing Administrator 1m f
Enclosure I
(
cc:
Region III Inspector - LSCS 3525N 8203030230 820224 PDR ADOCK 05000373 A
3 ODCM QUESTIONS ON LASALLE ODCM SECTION 8 1.
Provide the conservative assumptions that will be used to determine the exact alarm or trip setpoints from equations 8.1, 8.2 and 8.3 for the instruments listed in Technical Specification 3 3 7.11.
The equations should be developed in terms of the units used by the instruments, such as cr/hr, cpm, uCi/sec, etc.
Describe the method that will be used in plant procedures to establish the sensitivity for each type of monitor.
l Consider, also, the. post-accident monitors in ll.F.1 attachments 1 and 2 of NUREG-0737 2.
Provide the conservative assumptions that will be useo to determine the exact alarm or trip setpoints from equation 8.5 for the instruments listed in Technical Specification 3.3 7.10.
As In 1) above, the equation should be in terms of the instrument units.
Describe the method for establishing sensitivity for each type of monitor.
3 Provide the method to be used for Technical Specification 3.11.1.4 for LaSalle and include the parameters in ODCM Table 7.2-1.
I
RESPONSE
'1.
See revised ODCM section(s) 8.1 3, 8.1.4, 8.1.5 and 8.1.6.
2.
See revised ODCM section(s) 8.2.3 and 8.2.4.
3 LaSalle does not currently foresee the use of outside temporary tanks.
Should their use be considered in the future, a revision to the ODCM will be submitted.
- 1 I
r----
i
=...a' a
4+
, e e
LA SALLE 8.0 RADIOACTIVE EFFLUENT TREATMENT SYSTEMS, MODELS FOR SETTING GASEOUS AND LIQUID EFFLUENT MONITOR ALARM AND TRIP SETPOINTS, s
AND ENVIRONMENT RADIOLOGICAL MONITORING TABLE OF CONTENTS PAGE 8.1 GASEOUS RELEASES 8.1-1 8.1.1
System Design
8.1-1 8.1.1.1 Gaseous Radwaste Treatment System 8.1-1 8.1.1.2 Ventilation Exhaust Treatment System 8.1-1 8.1.2 Alarm and Trip Setooints 8.1-1 & 8.1-2 8.1 3 Station Vent Stack Monitor 8.1-2 6 8.1-3 8.1.4 Standby Gas Treatment Stack Monitors 8.1-3 s 8.1-4 8.1 5 SJAE Off-Gas Monitors 8.1-4 s 8.1-5 8.1.6 Off-Gas Post Treatment Monitors 8.1-5 8.1.7 Allocation of Effluents from Common Release Points 8.1-5 8.1.8 Symbols Used in Section 8.1 8.1-6 8.1 9 Constants Used in Section 8.1 8.1-6 8.2 LIQUID RELEASES 8.2-1 8.2.1
System Design
8.2-1 8.2.2 Alarm Setpoints 8.2-1 s 8.2-2 8.2 3 Liquid Radwaste Effluent Monitor 8.2-2 8.2.4 Liquid Effluent Monitors 8.2-2 s 8.2-3 8.2 5 Allocation of Effluents from Common Release Points 8.2-3 8.2.6 Administrative and Procedural Controls for Radwaste Discharges 8.2-3 8.2.7 Determination of Initial Dilution Stream Flow Rates 8.2-3 8.2.8 Symbols Used in Section 8.2 8.2-4
F LA SALLE 8.0 RADIOACTIVE EFFLUENT TREATMENT SYSTEMS, MODELS FOR SETTING GASE0US AND LIQUID EFFLUENT MONITOR ALARM AND TRIP SETPOINTS, AND ENVIRONMENT RADIOLOGICAL MONITORING 8.1 GASEOUS RELEASES 8.1.1
System Design
8.1.1.1. Gaseous Radwaste Treatment System A gaseous radwaste treatment system shall be any system desig'ned and installed to reduce radioactive gaseous effluents by collecting primary coolant system off gases from the primary system and providing for delay or hovdup for the purpose of reducing the total radioactivity prior to release to the environment.
8.1.1.2 Ventilation Exhaust Treatment System e
A ventilation exhaust treatment system shall be any system designcd and installed to reduce gaseous radiolodine or radioactive material in particulate form in effluents by passing ventilation or vent exhaust gases through charcoal adsorbers and/or HEPA filters for the purpose or removing iodines or particulates from the gaseous exhaust stream prior to the release to the environment (such a system is not considered to have any effect on noble gas' effluents).
Engineered Safety Feature (ESF) atmospheric cleanup systems are not considered to be ventilation exhaust treatment system components.
8.1.2 Alarm and Trip Setpoints Alarm and trip setpoints of gaseous effluent monitors at the principal points of re-lease of-ventilation exhaust air containing radioactivty are established to ensure that the release limits of 10 CFR 20 are not exceeded.
The setpoints are found by solving Equations 2 9 and 2.10 for each class of release.
For this evaluation the radioactivity mixture in the exhaust air is assumed to have the composition of gases listed in Table 3-3 from " Technical Derivation of BWR 1971 Dasign Basis Radioactive Material Source Terms," NEDO-10871, March 1973, General Electric Company.
This mixture of radioactive gases is representative of the activ-Ity found at the point of release from the fuel; radioactive decay has not been included.
8.1-1
r Equation 2 9 is rewritten using the fractional composition of each nuclide, f.
and a total release rate Q, for station vent stack
- releases (the principal poinE,of release of ventilation exhaust air containing radioactivity):
1.11 Q
(S.
x
- f. )
500 ts i
i yr (g,))
i f.
Fractional Radionuclide Composition The release rate of radionuclide i divided by the total release of all radionuclides.
Q Total Release Rate, (uti/sec) ts Vent Stack Release The release rate for all radionclides due to a station vent stack release.
Q
(.2)
Q;3
=
ts I Equation 8.1 can be solved for Q f r release limit determinations.
t Similarly, Equation 2.10 can be rewritten:
(%/Q)s ts. exp(- A.R/3600u ) +
Q f
,i i
s 1.11 S Q f
< 3000 "'**
(8.3)
I ts.i.
yr Equation 8.3 can be solved for Q and a corresponding release limit be determined.
The most conservative release lim!t determined from Equations 8.1 and 8.3 will be used in selecting the appropriate alarm and trip setpoints for a vent stack release.
The exact settings will be selected to ensure that 10 CFR 20 limits are not exceeded.
Surveillance frequencies for gaseous effluent monitors will be as stated in Table 4.3.7.11-1 of the Technical Specifications.
Calibration methods will be consistent I
with the definitions found in Section 1.0 of the Technical Specifications.
8.1 3 Station Vent Stack Monitor OPLD5J Releases of radioactive noble gases from the station vent stack release point are monitored by an offline monitoring system consisting of three instrument channels.
Samples of the effluent stream are taken by an isokinetic probe just prior to discharge into the atmosphere.
Gas flow through the monitoring system is provided by vacuum pumps, one for the low range detection system and one for the mid and high range detection systems.
A sample conditioning skid, upstream of the de-tection system, filters particulate and iodine and provides for collection of par-ticulate and iodine grab samples.
OT".e tern " vent stack", as used in this section, is to be considered synonymous with
" stack" as used in Section 2.1.
8.1-2
The low range detection system consists of a beta scintillation detector, a shielded I
sampling chamber and a pre-amplifier.
The mid and high range detection systems con-sist of solid state CdTe (Cl) detectors, shielded sample chambers and pre-amolifiers.
Signals from the three detection systems are processed by a microprocessor which also controls the system pumps and monitors process stream and sample flowrates.
The individual detection system outputs and other system parameters are displayed on a digital readout and control module.
A three-pen recorder is utilized to record the individual detection system results in uCi/oc. The detection system whose output is indicative of the existing release activity is converted by the microprocessor to uCi/second utilizing the existing process stream flowrate and recorded on a r, ingle pen recorder. This uCi/second value is also compared to an operator entered alarm point.
The recorders and digital readout and control module are located in the main control room.
The sample conditioning skid, detection skid and microprocessor are located in the auxiliary building on the 796 foot 6 inch elevation.
Power is supplied to this monitor from Division 1 power.
Detector efficiencies are initially determined by calibration with Xe-133 gas. 'Once operational, ef ficiency factors will be based on monitor response and isotopic analysis data.
The alarm setpoint for this monitor will be selected to ensure that the combined release rate of the station vent stack and SGTS stack does not exceed the most conservative release limit determined from equations (8.1) and (8.3) by setting the alarm point at or below one-half the release limit.
8.1.4 Standby Gas Treatment Stack Monitors Release of radioactivity from the standby gas treatment system (SGTS) stack is monitored by one of three SGTS monitoring systems.
Two of the systems consist of a beta sensitive scintillation detector for particulate; a beta sensitive scintilla-tion detector for low-range noble gas; a beta sensitive scintillation detector for high-range noble gas; and a gamma sensitive scintillation detector for lodine.
Pro-visions are made for system inlet and outlet grab samples.
The monitoring system uses a microprocessor to analyze the data from the beta and gamma scintillation detectors.
This microprocessor performs background subtraction
'and compares the radiation values against operator entered alarm limits.
A four-pen strip chart recorder ~ records the monitoring system output.
Alarms are located in the main control room.
Power is supplied to this monitor subsystem from Division 2 power.
The equipment for each monitoring channel is skid mounted and located on the 786 foot 6 inch elevation in the auxiliary building.
The third SGTS monitor (OPLD2J) utilizes an isokinetic probe to sample the effluent stream prior to discharge into the atmosphere.
The offline monitor consists of three detection systems.
Gas flow through the system is provided by vacuum pumos, one for the low range detection system and one for the mid and high range detection systems.
A sample conditioning skid, uostream of the detection system, filters particulate and iodine and provides for collection of particulate and iodine grab samples.
8.1-3
....... ~.
l The low range detection system consists of a beta scintillation detector, a shielded I5 sampling chamber and a,nre-amplifier.
The mid and high range detection systems con-
}
sist of solid state CdTe (Cl) detectors, shielded sample chambers and pre-amplifiers.
Signals from the three detection systems are processed by a microprocessor which also controls the system pumps and monitors process stream and sample flowrates.
The individual detection system outputs and other system parameters are displayed on a digital readout and control module.
A three pen recorder is utilized to record the individual detection system results in uti/cc.
The detection system whose output l,
is indicative of the existing release activity is converted by the microprocessor to uti/second utilizing the existing process stream flowrate and recorded on a single pen recorder.
This uCi/second value is also compared to an operator entered alarm point.
The recorders and digital readout and control module are located in the main control The sample conditioning skid, detection skid and microprocessor are located room.
in the auxiliary building on the 796 foot 6 inch elevation.
Power is supplied to this monitor from Division 2 power.
Detector efficiencies are initially determined by calibration with Xe-133 gas.
Once operational, efficiency factors will be based on monitor response and isotopic analysis data.
The alarm setpoint for this monitor will be selected to ensure that the combined release rate of the station vent stack and SGTS stack does not exceed the most conservative release limit determined from equations (8.1) and (8.3) by setting the alarm point at or below one-half the release limit.
8.1 5 SJAE Off-Gas Monitors The steam jet air ejector (SJAE) monitor subsystem continually measures and records the gamma radiation in the off gas as it is drawn from the main condenser by the steam jet air ejectors before it passes through the holdup line and carbon beds enroute to the station vent stack.
A continuous representative sample is drawn from the off gas system via a stainless steel sample line.
A 14 cc serum vial is inserted into the sample chamber, evacu-ated, then filled with a representative sample of off gas.
This sampling equipment is located on panel 1D18-J034 (2D18-J034).
This monitor system consists of two channels.
One channel contains a gamma sensi-tive ionization chamber and a linear radiation monitor and the other channel contains a gamma sensitive ionization chamber and a logarithmic radiation monitor.
The ion chambers sensitivity is 1 to 106 mR/hr.
The gamma sensitive ionization chamber RE-1D18-N002 (RE-2D18-N002) is connected to the logarithmic readout channel.
This channel has alarm functions but no trip functions.
Power is supplied from Unit 1 (2) 125-Vdc power supply via inverters and from the 120-Vac instrument bus for the recorder.
The gamma sensitive ionization chamber RE-1D18-N012 (RE-2D18-N012) is connected to the linear readout channel.
Power is supplied to this channel from Uni
- 1 (2) 24-Vdc power supply and from the 120-Vac instrument bus for the recorder.
Both channels measure the radiation levels in the off gas and their recorders are located in the control room.
B.1-4
l 1
The initial alarm setpoin't for the logarithmic SJAE off gas monitor is established et or below the Technical Specification 3 11.2.7 off gas release rate limit using an empirical relationship between mR/hr and uCi/second at design off gas flowrates.
Once operational, the monitor response and measured uCi/second off gas data will be used to determine the alarm setpoint at or below the Technical Specification limit.
8.1.6 Off-Gas Post Treatment Monitors The off gas post treatment monitor subsystem continually measures and records the grmma radiation in the off gas after it has passed through the holdup line and cerbon beds.
A continuous representative sample is drawn from the system by one of two vacuum pumps.
This monitor' system consists of two identical channels consisting of Nal (TI) activated scintillation detector's, shielded sample chambers, pre-amplifiers and log count rate monitors.
The log count rate monitor includes an integral power supply, for providing high voltage to the detector, and trip relays whose outputs initiate alarm annunciators and isolate the flow of off gas to the stat:en vent stack.
The off gas isolation setpoint will be at or below one-half the station vent stack release limit and is converted into the monitor units of cps:
Release limit (uCi/sec) x Efficiency p,
ut cc (8.4)
L.72E2 (cc/sec)cfm cfm )
where cfm = off gas flowrate The initial ef ficiency factor is determined by calibration with Cs-137/Ba-137m solution.
Once operational, the monitor response and measured uCi/second off gas data will be used to determine the efficiency factor.
The sample panel with pumps, detectors, shielded sample chambers and pre-amplifiers are located in the Off-Gas Filter building on the 690 foot elevation.
The log count rate monitors and two channel recorder are located in the main control room.
Power is supplied to these monitors from Unit 1 (2) 24-Vdc power supply and f rom the 120-Vac instrument bus for the recorder.
8.1.7 Allocation of Effluents from Common Release Points Radioactive gaseous effluents released from the plant vent stack are comprised of contributions from both units.
Estimates of noble gas contributions from each unit will be allocated by considering appropriate operating conditions and measured SJAE off gas activit'ies.
Allocation of radiciodine and radioactive particulate releases to a specific unit it not as practical and is influenced greatly by in-plant leakage.
Under normal operating conditions, allocation will be made using reactor coolant iodine activities.
During unit shutdown or periods of known maj o r in plant leakage, the apportionment will be adjusted accordingly.
The a l l oca t i o's of the effluents will be estimated on a monthly basis.
8.1-5
8.1.8 Symbols used in Section 8.1 SYMBOLS NAME UNIT Q
Total Release Rate, Vent Stack Release (uC1/sec) 3 5';
Gamma Whole Body Dose Constant, Vent Stack Release (mrad /yr per uti/sec) f; Fractional Radionuclide Composition II; Beta Skin Dose Constant (mrem /yr per uCI/m )
(X/Q)*
Relative Effluent Concentration, Vent 3
Stack Release (sec/m )
A; Radiological Decay Constant (hr-I)
I R
Downwind Range (m) u, Average Ilind Speed, Vent Stack Release (m/sec)
Q.
Release Rate of Nuclide i, Vent Stack Release (uCi/sec)
S; Gamma Dose Constant, Vent Stack Release (mrad /yr per uCi/sec) 8.1 9 Constants Used in Section 8.1 NUMERICAL VALUE NAME UNIT 1.11 Conversion Constant (mrem / mrad) 3600 Conversion Constant.
(sec/hr) 8.1-6
8.2 LIQUID RELEASES 8.2.1
System Design
A liquid radwaste treatment system shall be a system designed and installed to reduce radioactive liquid effluents by collecting the liquids, providing for retention or holdup, and providing for treatment by demineralizer or a concen-trator for the purpose of reducing the total radioactivity prior to release to the environment.
8.2.2 Alarm Setpoints Alarm setpoints of liquid effluent monitors at the principal release points are established to ensure that the limits of 10 CFR 20 are not exceeded in the un-restricted area.
The concentration limit (C ; ) in the discharge line prior to j
dilution in the initial dilution stream is:
~
id r
F F
ave +
max C.
= MPC ilm r
p
. max (8.5)
C'.
Limiting Concentration (uCi/ml) in Discharge Line The maximum concentration in the discharge line permitted to be discharged to the initial dilution stream.
MPC Weighted Maximum Permissible (uCi/ml)
Concentration n
n 11 C 25 k MPC = i=1 i
or i=1 i
A n
C.
n I
8 E
i=i MPC.
i=1 MPC.
I i
where C; = uti/mi of nuclide i MPC, = Maximum Permissible Concentration, 1
uCi/ml of nuclide i Ek uti of nuclide i released in time t
=
F Maximum Flow Rate, Radwaste (f t /sec)
Discharge The maximum flo.4 rate of radwaste from the discharge tank to the initial dilution stream.
l d
F Average Flow Rate, Initial (ft /sec) j Dilution Stream l
l The average flow rate of the initial dilution stream which carries the radionuclides to the unrestricted area boundary.
l 8.2-1
Surveillance frequencies for liquid effluent monitors will be as stated in Table 4.3.7.10-1 of the Technical Specifications.
Calibration methods will i
be consistent with the definitions found in Section 1.0 of the Technical Specifications.
8.2 3 Liquid Radwaste Effluent Monitc r The liquid radwaste discharge line is continuously monitored for radioactivity by an offline monitoring system which uses a Nai (TI) activated scinti';ation detector.
Liquid effluent flow through '.he monitor is provided by a pumo lo-cated on a local sample panel.
The monitoring system consists of a scintillation detector, shielded sampling chamber, a pre-amplifier, and a log count rate monitor.
The log count rate monitor includes an integral power supply, for providing high voltage to the detector, and trip relays, whose outputs initiate high radiation alarm annun-ciators and initiate isolation of the liquid radwaste discharge header.
The radwaste discharge effluent monitor provides signals to a recorder in the main control room and a recorder in the radwaste control room.
The monitor is powered from a local 120-Vac source through a d-c power supply and has the equipment identification number OD18-K606.
The alarm setpoint for the liquid radwaste discharge monitor is established at or below the maximum concentration determined in equation (8.5).
The con-centration is converted to an alarm setpoint in cpm using an efficiency curve developed for the monitor through use of a Cs-137/Ba-137m liquid calibration and solid source responses.
8.2.4 Liquid Effluent Monitors The Unit 1 (2) service water effluent header and Unit 1 (2) RHR service water effluent headers are continuously monitored for radioactivity by an offline monitoring system which uses a Nat (TI) activated scintillation detector.
Liquid effluent flow through each monitoring system is ensured by a pump located on local sample panels.
g Each monitoring system consists of a scintillation detector, shielded sampling chamber, a pre-amplifier, and a log count rate monitor.
The log count rate monitor includes an integral power supply, for providing high voltage to the detector, and trip relays, whose outputs initiate high radiation alarm annunciators.
The service water effluent monitor provides a signal to a two pen recorder which it shares with the RBCCW process radiation monitor.
The RHR service water effluent monitors share a common two pen recorder in the main control room.
Al' the process liquid monitors have logarithmic scales with a range of 10 to 6
10 CPM.
The monitors are powered from the Unit 1 (2) 125-Vdc batteries via inverters.
8.2-2
The equipment identification numbers for the monitors are 1018-K608 (2D18-K608),
I service water effluent monitor; 1018-K604 (2018-K604), RHR service water A ef fluent; and 1D18-K605 (2D18-K605), RHR service water B effluent.
Alarm setpoints for these monitors are set at twice the normal full power back-ground reading to give indication of a significant change in the level of radio-ectivity monitorcd.
8.2.5 Allocation of Effluents from Common Release Points Radioactive liquids released from the radwaste treatment system are comprised of contributions from both units.
Under normal operating conditions, it is difficult to apportion the radioactivity between units.
Consequently, alloca-tion will normally be made evenly between units.
During refueling outages or periods of known major in plant leakage, the apportionment will be adjusted i
accordingly.
The allocation of the effluents will be estimated or. a monthly basis.
8.2.6 Administrative and Procedural Controls for Radwaste Discharges Administrative and procedural controls have been designed to ensure proper control of radioactive liquid radwaste discharge in order to preclude a release in excess of 10 CFR 20 limits.
The discharge rate for each batch is calculated by a technician and then independently verified by cperating staff personnel.
All liquid radwaste discharges will be from one of two river discharge tanks, 1WF05T or 2WF05T.
The keylock hand switch, OHS-WF048, used for selecting high or low discharge flow Is kept locked except when discharging.
The key for this switch and the locked.
valves is under the administrative control of the Shi'?t Engineer.
A documented valve checklist is prepared for each batch discharge.
The proper valve line-up is made by the Operator and rechecked by the Radwaste Foreman.
The actual discharge is authorized by the Shift Engineer.
The system is equipped with a radiation trip point which alarms and initiates
' automatic valve closure on the radwaste discharge line to prevent the violation of 10 CFR 20 limits.
8.2.7 Determination of Initial Dilution Stream Flow Rates For those releese paths which have installed flow monitoring instrumentation, that instrumentation will be used to determine the flow rate of the initial dilution stream.
This instrumentation will be operated and maintained as prescribed by the Technical Specifications.
For those release paths which do not have installed flow monitoring instrumentaion, flow rates will be deter-mined by use of appropriate engineering data such as pump curves, differential pressures, or valve position indication.
8.2-3
G
'a 8.2.8 Symbols Used in Section B.2 fj
^
SYMBOL NAME UNIT C;
Limiting Concentration in Discharge (uti/ml) y Line MPC Weighted Maximum Permissible (uCi/ml)
Concentation 3
F M ximum Flow Rate, Radwaste (ft /sec) ax Discharge d
F Average Flow Rate, initial (ft /sec)
Dilution Stream l
l l
i 1
l 8.2-4
__ _ _ _ _