ML20058P633
| ML20058P633 | |
| Person / Time | |
|---|---|
| Site: | Zion File:ZionSolutions icon.png |
| Issue date: | 05/03/1993 |
| From: | Perchiazzi W COMMONWEALTH EDISON CO. |
| To: | |
| Shared Package | |
| ML20058P067 | List: |
| References | |
| NUDOCS 9310250131 | |
| Download: ML20058P633 (9) | |
Text
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ZION STATION i
CONTROL ROOM HABITABILITY REPORT B
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(
)
i Prepared by:
William T. Perchiazzi P.E.
1 Mechanical & Structural Design Engineering HVAC Group May 3,1993 4
e 9320250232 930901 DR ADDCK 05000295 PDR J
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1.0 INTRODUCTION
f This submittal provides an evaluation of the Zion Station Control Room Habitability l
in conformance to GDC 19. The sections which follow present the analysis of the control room operator exposure from airborne radioactive material resulting from a design basis LOCA accident.
2.0 RADIOLOGICAL CONCERNS The Zion station dose analysis has been reevaluated as a result of the discovery of unfiltered air inleakage. The following sections detail the analysis performed to ensure the station conforms to GDC 19. The radiological release considered was the design basis loss of coolant accident with ensuing primary containment leakage and ESF leakage.
3.0 ASSUMPTIONS USED IN THE ANALYSIS 3.1 Basic Assumptions The following assumptions were used in the analysis:
A Loss of Coolant accident is postulated to occur on unit 2. The radiological-impact from the Unit 1 LOCA is less severe due to the proximity of the control room intakes.
The fraction of initial source released to the unsprayed containment volume is 1.0. This is conservative because spray removal does not occur until radiciodine is transported from the unsprayed to the sprayed volume.
Elemental iodine plateout in the containment is conservatively ended when i
the elemental iodine decontamination factor is reached; thus the plateout ends when the spray removal ends for elemental iodine.
The start time for the ECCS leakage and the leakage back to the RWST are both assumed to be 15 minutes. This is a conservative assumption since the injection spray lasts at least 15 minutes; thus, the recirculation spray cannot start before 15 minutes after the start of the accident.
The source term for the leakage back to the RWST is conservatively assumed to be independent of the other type leakage; thus, one leakage type does not remove source activities for the other type.
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4.0 DESIGN INPUTS FOR ANAL.YSIS P
4.1 Desian Basis Source Term The initial airborne iodine and noble gas activities in the containment are 25% and 100% of their core inventories respectively which are released instantaneously (Reference Reg Guide 1.4). 50% of the core inventory of iodine is in the sump water (Reference SRP 15.6.5, Appendix B, NUREG-0800, Rev.1, July,1981).
The following table summarizes the end of life core inventory for operation at 3391MWt (about 104% of full power)
Core Inventorv of lodine and Noble Gas Nuclide Activity Nuclide Activity Nuclide Activity Curies Curies Curies 1-131 9.34E + 7 Kr-85m 2.70E + 7 Xe-133m 4.94E + 6 i
1-132 1.38E + 8 Kr-85 9.4E + 5 Xe-133 1.88E + 8 l-133 1.76E + 8 Kr-87 5.08E + 7 Xe-135m 5.20E + 7 l-134 2.19E + 8 Kr-88 7.70E + 7 Xe-135 5.24E + 7 l-135 1.78E + 8 4
9 k
f 3
7 h
i 4.2 Containment Information Used Three Reactor Containment Fan Coolers will be operating with a flow rate of 66000 CFM per Fan. -(Reference UFSAR Table 6.2-1 and Section 15.6.5.4.4.1)
Containment Free Volume of 2.715E+6 Cubic Feet J
(Reference UFSAR Section 15.6.5.4.4.3)
Fraction of Containment Volume Sprayed.8613 (Reference S&L Calculation ATD-0214,Rev 0)
Containment Leak Rate:
0 - 24 Hours
.1% per day 24-720 Hours
.05% per day (Reference Reg Guide 1.4, Zion Technical Specifications, Appendix A, 15.6.5.5.6.2)
Subsection 3.10.1.A.1.a. UFSAR Section
~"
Distribution of lodine Species 91% Elemental 4% Organic 5% Particulate.
(Reference Reg Guide 1.4)
The Containment sump contains fluid from the following sources:
12,760 Cu Feet
- a. Reactor Coolant 818 Cu Feet
- b. Accumulator Tank (Each,4 Tanks) 350,000 gallons
- c. Refueling Water Storage Tank 5,000 gallons
- d. Spray Additive Tank 6.3-4,6.3-3,6.3-10, 6.5-3 and Appendix 158)
(Reference UFSAR Tables The Boron injection Tank is in the process of being removed at Zion.
Note:
It is included in the analysis since the modification is not complete on the unit. The change in the analysis in not significantly affected by this volume.
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1 4.3 Control Room Information i
h final
_-The X/O evaluation combined a number of parameters to determ ne t e values. Zion Station had extensive wind tunnel testing performed on a i
model of Zion Station. This provided the value of X/Q from the Containment l
Structure to the EDG Intake. The EDG intake would provide the quickest
'l pathway to the' control room filtered air intake through the EDG Fans which take suction on the west side of.the Aux Building and exhaust into the j
turbine building relatively close to the emergency makeup filter unit air intake j
for the control room. Additional tracer gas testing was performed by the station to determine the dilution factor for the air transport from the EDG ~
intake to the control room intake to further quantify the X/O values.
Atmospheric dispersion factors for the duration of the accident are as folloWs*
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l X/O Data (sec/m )
r Makeuo Air Intake Time Interval (hours) 6.870E-4 0 to 8 Hours 4.053E >
8 to 24 Hours _
' 2.576E-4..
~24 to 96 Hours 1.134E-4 96 to 720 Hours (Reference S&L Calc ATD-0194, Rev. O and Murphy Campe) t J
Make up Air Flow rate of 1600 CFM was used. _This is the minimum expected flow rate for the filtered air intake. This flow rate is less than the initial design of 2000 CFM however, historically the station has had difficulty meeting the design flow of 2000 CFM. Reducing the flow rate to 1600 CFM will provide a higher exposure which is conservative. This is proven in the latest revision of ATD-0190, Rev 2 where the dose rates for [
the various possible system flowrates are calculated.
l The filter unit consists of a HEPA Filter and two 2" carbon adsorbe efficiency for the unit has been taken to be 99%. The station has added a manifold to ensure both adsorber banks are leak tested as required by Reg Guide 1.52. In addition the laboratory analysis of the used carbon has been conducted at 30 C and 95% RH since no heaters are installed in thi unit. The laboratory testing is conducted as a four inch bank with I
acceptance criteria less than.175% penetration. The station is currently
-l testing the samples as required by the current technical specifications and the proposed upgrade to allow utilization of a 99% filter efficiency.
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Control Room Information (Continued)
The unfiltered inleakage will be taken from an actual inleakage test report.
The value of inleakage in the most recent report is 1205.24CFM. Zion station has gone through an extensive inteakage reduction effort to reduce inleakage. The predominant source of the unfiltered air inleakage is from the negative pressure duct and equipment located outside the control room boundary in the HVAC Equipment Room. (Reference Lagus Technologies Test Reports)
Control Room Calculated Volume = 119,122 Ft (Reference S&L Calc PV-101)
Personnel Breathing Rate =3.47E-4 cubic meters /sec (Reference Murphy Campe)
P Occupancy Factors 0 - 24 Hours 100 %
1.0 1-4 Days 60 %
0.6 4-30 Days 40 %
0.4 (Reference Murphy Campe and 6RP 6.4) -
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o 4.4 Containment Sorav Data Containment Spray Pump Flow rates Normal Spray Mode 2615 GPM/ Pump 5230 GPM Total 2 of 3 Pumps (Reference UFSAR 15.6.5.4.4.1)
Recirculation Spray Flow 2460 GPM (Reference S&L MAD Calculation 91-0083)
Duration of Spray time is four days following the event. This is being incorporated in tne Zion Emergency Operating Procedures.
Spray Removal Rates (1/Hr) for iodines:
Elemental (One or two pumps and DF<200) 20 Particulate (Two injection Pumps and DF< 50) 10.3 Particulate (One injection Pump and DF<50) 5.13 Organic (Two injection Pumps)-.
1._0687"
~
.03663 Organic (One injection Pump)
Elemental lodine Plateout Rate (1/Hr) 2.41 200 Elemental lodine Decontamination Factor (Reference S&L ATD Calculation Zl-5-91)
.03246 Organic (Recirculation Pump)
(Reference S&L Calculation ATD-0206,Rev 1)
.1 Particulate lodine Spray Rate Reduction Factor at DF of 50 (Reference SRP 6.5.2, NUREG 800, Rev. 2) 7
n 4.5 ESF Leakaae Evaluation of the radiologicalimpact of fission product leakage from the engineered safety features (ESF) was based on the following assumptions:
J ESF leakage occurs in the auxiliary building from the components and joints of the safety systems during recirculation. The leak rate is assumed to be 3540 cc/hr, based on twice the maximum operationalleakage.
(Reference UFSAR Table 6.3-9 and SRP 15.6.5)
Leakage starts at the beginning of recirculation phase when the sump water is circulated outside the containment (15 Minutes after the accident, see basic assumptions), and is assumed to remain constant for the course of the accident.
10 percent of the iodine in the water which leaks becomes airborne, and is instantly picked up by the ventilation system and released to the atmosphere via the vent stack.
(Reference SRP 15.6.5, NUREG 800, Rev 1)
Auxiliary Building Ventilation system.has a system consisting of HEPA and Carbon filters. A 90.% removal efficiencyls used for the filtration system.
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(Reference FSAR Question 09.8) 4.6 RWST Leakaoe to Atmosohere Leakage back to the RWST during the Recirculation phase of the LOCA is estimated to be 30 cc/Hr total.
10 percent of the iodine in the water which leaks back to the RWST becomes airborne and is vented to the atmosphere. No filtration credit is taken for this release path since it is vented directly to the atmosphere. The RWST vent is near the containment / auxiliary building wall interface. The leakage will follow the same path as the containment leakage for the analysis.
(Reference Chron #192445, Letter to G. P Lahti, S&L from William Perchiazzi, CECO Dated September 30,1992)
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F 5.0 RESULTS OF THE ANALYSIS The following 30 day Post LOCA control room personnel exposures were determined due to containment leakage, ESF leakage and unfiltered inleakage into the control room boundary:
Filter Unit Makeup Flowrate = 1600 CFM 1
Zion C.R.
(Rem) 24.07 30.0 Thyroid Dose Whole Body Dose
.2639 5.0 Skin Dose (Beta and Gamma) 3.692 30.0 The inleakage value used in the analysis was the maximum measured inleakage (144CFM)from the most recent testing performed at Zion Station by Lagus Technologies. The infiltration which will yield 30 Rem Thyroid dose has also been determined to: identify the-margin. associated with the infeakage_used. An inleakage of 188.4 CFM would make the thyroid dose rise to the GDC 19 limit of 30 Rem. Therefore, the analysis also shows the margin of safety associated with the current plant conditions.
(Reference S&L Calculation ATD-0190, Rev 2) i
6.0 CONCLUSION
E The Zion Control room exposures are calculated to be below the limits established by GDC-19 therefore the control room is expected to remain habitable under the design basis LOCA radiological conditions.
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