ML20245F271
| ML20245F271 | |
| Person / Time | |
|---|---|
| Site: | Quad Cities  |
| Issue date: | 01/31/1984 |
| From: | Billig P, Rogers A GENERAL ELECTRIC CO. |
| To: | |
| Shared Package | |
| ML20245F260 | List: |
| References | |
| AE-05-0184, AE-5-184, NUDOCS 8908140221 | |
| Download: ML20245F271 (15) | |
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~7h AE-05-0184 ORF No. E31-00028 QUAD CITIES 1 AND 2 HPCI/RCIC ROOM LEAK OETECTION
-PHASE I REPORT l
8y: A(.);/7//h, P.F.Billig l
Approved by: # M A. E. R(gers. Manager Plant Performance Engineering l
January 1984 O
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4' LEGAL NOTICE Except as otherwise agreed to in writing, neither the General Electric Company nor any of the contributors to this document makes any warranty or representation (express'or implied) with respect to the accuracy, completeness, or usefulness of the information contained in-this document or that the use of such information may not infringe privately owned rights, nor do they assure any responsiblitty for liability or damage of any kind which may result from the use of any of the information contained in this document.
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I TABLE OF CONTENTS 1.0 Introduction
1.1 Background
1.2 Approach P.0 Discussion 2.1 HPCI Room Review 2.2 RCIC Room Review O
2.3 Control System Logic Review 2.4 Additional Review 3.0 Conclusions and Recommendations 4.0 References Appendix A: Information Required for Phase II & !!!
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1.0 q(/ Introduction
1.1 Background
Each High Pressure Coolant Injection (HPCI) and Reactor l- Core Isolation Cooling (RCIC) room at Quad Cities Station Units 1 and 2 currently contains sixteen temperature switches to detect significant leaks in the HPC:/RCIC steam piping and initiate isolation of the steam lines.,
Reducing the nurrber of temperature switches from sixteen to four in each room would reduce the likelihood of unnecessary ' system isolations; additionally the calibration burden and potential for the issuance of a Licensee Event Report would also be reduced significantly since the sixty-four (16 in each room in both units) existino switches require calibration once each operating cycle.
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This report represents Phase I in an effort to reduce the number of temperature switches in the HPCI/RCIC rooms.
The purpose of Phase I is - to discuss qualitatively the chances of success. Phases II and III will analyze the temperat'Jre response of possible steam leaks in the HPCI and RCic rooms respectively. The last two phases will also provide recommendations on switch relocation, shielding or setpoints, if recuired, to support reduction in the number of switches.
1.2 Approach Phase ! consists oY a review of the room geometry, heating and cooling capability of equipment, location of temperature switches and current setpoints for the Quad Cities 1 and 2 HPCI and RCIC rooms. The purpose of this review is to determine the likelihood that the Phase ::
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{ ?~ and III analyses will show that adeouste leak detection k, .is provided by a single group of four temperature switches in each econ L
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L An additional review is also performed on the HPCI/RC!C area high temperature isolation control systen logic.
The purpose of this review is to assure that four temperature switches will comply with th* safety design basis and other NRC regulations.
I 2.0 Discussion 4
7.1 PPCI Room Review The HPCI pump rooms at Ouad Cities are situated in the
" reactor building. There are two rooms, one for each' reactor, and they are essentially identical.
t A, The drawings transmitted to GE in Reference 1 show that each room has an approximate floor area of 1400 square
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From drawings in the Safety Analysis Report (SAR) the total . volume of the room is estimated to be 52.000 cubic feet.
Each HPCI room has a Buffalo Forge Model HV room cooler.
The cooler is rated at 200 M8tv/hr while the fan has a .
4950 CFM rating at 110*F. The cooler fans start at 94*F.
Diesel generator initiation is necessary for the cooling water pumps.
The HPCI room is also connected to the reactor building ventilation system.
- The HVAC vent in the HPCI room has a 475 SCFM capacity and will isolate on a high (2 mrem) radiation signal.
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- .l A fire protection system is present in the HPCI room.
This system is triggered when the sensors detect 175'F.
The sensors are lor.ated near the pumps / oil storage area.
From Reference 1, the HPCI compartments have i double are door between them. Each compartment has a submarine coor to the torus area, but since it is always closed during operation ' and is able to withstand large pressures, it.
can be neglected as a flow path. A fire door to ?e turbine building basement is also found in each WPC*
room. ~
~The exact size of these flow passages and the existence of blowout panels is unknown at this time.
The HPCI compartment contains sixteen temperature sensors in four groups of four. Each group is located near a potential steam leak source to minimize the leak de-tection time. The four locations are above the HPCI steam inlet line, above the turbine rupture disk, and one group at each end of the turbine near the bearings. The sensors are set to actuate at 185'F.
Each switch group is arranged in a one-out-of two twice logic to initiate steam supply line isolation. This logic allows for proper operation even if one senser fails closed or fails to close. Therefore, a single failure does not eliminate any group. The control logic for the temperature sensors is discussed further in Section 2.3.
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2.2 RCIC Room Review The RCIC pump rooms at Quad Cities are located in the reactor building adjacent to the HPCI rooms. As with Pe
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HPCI system the two rooms are separate, one per reactor, ]
and essentially identical.
j From Reference 1 the floor area of each room is estim {
to be 680 square feet. From drawinos in the SAR the total volume of the room is computed as 25,700 cubic '
feet. The RCIC room is about half the size of the MPCI room.
Each RCIC room has a Buffalo Forge Model HV room cooler.
The cooler is rated at 340 MBtu/hr 'with a fan rating of 8500 CFM at ,110*F. The setpoint and power requirements of the fans are identical with those of the HPCI room.
The RCIC compartment is also connected to the reactor building ventilation system. The HVAC vent capacity in the RCIC room is 1900 SCFM.
The major heat sources in the RCIC room are the RCIC pump and piping, a core spray pump and the HPCI turbine exhaust line which passes through the room. The presence of all of theu heat sources accounts for t ? larger cooling capacity over the HPCI room.
The RCIC rooms have a single fire door between the rooms, .
and each room has a submarine door to the torus basement area. Since the submarine doo'r is not expected to fail during transtants, it can be neglected as a possible flow path. The existence of blowout panels still needs to be detemined.
The RCIC compartment contains sixteen temperature sensors in four groups of four. Each group is located near a potential steam leak source. The four locations are above the RCIC turbine at the rupture disk, near the steam supply to the turoine, and at both ends of the
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f turbine At the shaft.
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. The control logic for the switches is identical to that i for the sensors in the HPCI compartment and is discussed further.in Section 2.3.
Frnm the data presented in Reference 1 it apoears that there is no fire protection system in the RCIC room.
2.3 Control System t.ogic Review The safety design basis for electrical systems in a' nuclear power plant is that the system must satisfy the single failure criterion. This criterion is defined in the General Design Criteria. From 10CFR50 Appendix A (Reference 3) the following is required: 4
" Single failures of passive components in electrical systems should be assumed in designing against a single failure."
If the ' number of temperature switches is reduced in each room from sixteen to four, the safety design basis. can still be met as long as- the four remaining switches are distributed in some form of parallel arrangement. If all four switches are in parallel, then four failures would i be required (i.e. all four switches) to fail the system.
However, a false signal could be sent if any of the four l malfunction and incorrectly measure a high temperature. }
j This arrangement is.filustrated in Figure 1. '
Another possible configuration is to use the present arrangement of each of the four groups of four for the proposed system. This is shown in Figure 2. This configuration requires two failures to fail the system.
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,,)( which meets the safety design basis.
It also has the advantage of reducing the probability of spurious signa as it reovires a one-out-of-two twice logic to cause steam supply line isolation.
The major disadvantage with the second configuration is that two sensors must record a high temperature. This could cause a substantial delay in the isolation signal as the four sensors may not be as close together as each group raf four are now.
The recommettdation for the type of isolation control logic will come from the Phase !! and III studies.
2.4 Additional Review The present configuration is redundant so that a single failure would not cause the loss of any tempera ture
( monitoring location.
If the number of switches were reduced to four, then for a single failure a monitoring j station would be lost. Therefore, the leak detection 1 time would increase if the leak were located near the failed sensor. However, the rooms are fairly small, so that temperature effects of a small (5 to 25 gpm) leak should travel quickly. The Phase II and III analyses would determine the response time.
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A review of the General Electric Standard Plant (BWR/6, Mark III) shows, that although it doesn't have a HPCI system, it does have a RCIC system. The RCIC pump room
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is located in the auxiliary room and is similar in size to Quad Cities. Sniall steam leak detection is provided i
by four temperature sensors above the equipment used to provide ambient conditions and two pairs of temperature sensors in the ventilation ducts used to measure the o
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temperature difference across the vent.
' divided The sensors are into two seDarate and systems. redundant electrical A
review with General- Electric licensing personnel indicates that enere should be no regulatory croblem with this temperature switch reduction project. However, at this time it appears that a Technical Specification change' may be needed for this modification. Therefore, this work might not fall under 10CFR50.59 and formal N2C approval woyld be required.
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Figure 1: Four in Parallel Temperature Switch Configuration G
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Configuration
N (qdi 3.0 Conclusions and Recommendations A review of the.HPCI and RCIC pump rooms indicates that adequate leak detection should be provided if the number of.
temperature sensors is reduced from . sixteen to four.
- nently in each room the sixteen sensors are- arranged. in
- r groups of four near possible steam leak locations. Four-separate temperature switches would be able to cover the same four locations; however, an analysis is recuired to detemine if the leak detection time may be increased by- the new configuration.
One important concern in the HPCI room is that the temperature -
sensors for the fire protection system are set lower than the sensors for the steam isolation. This indicates that there is a good probability that the fire protection spray would come on before a high temperature signal is recorded for isolation.
This concern will be addressed in Phase !!. If there is a
^ fire protection system in the RCIC room the effect of that system will be detemined in Phase !!!.
Phase I does not secommend locations for the t a perature sensors if the number is reduced. The follow-up work will determine which locations are the most ideal.
In conclusion there is a good chance of success for the temperature sensor reduction in the HPCI and RCIC compartments. GE recommends that the temperature response analyses of Phases !! and !!! be done.
Appendix A documents addi.tional infomation needed for the Phase !! and !!! studies. This information will be required before the work can begin.
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(etter K. Dages (CECO) to P. P. Stancavage (GE). " Transmittal of Information Required from Ceco for HPCI-RCIC Temperature Switch Analysis," December 6,1983.
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GE Proposal No. 656 CH013-EE1,2, "Estimata for Analysis of HPCI/RCIC Area Hich Tempera ture Isolation System Leak Ce-p tection Capability " July 26, 1983.
- 3. ICCFR50, Appendix ' A.
" General ' Oesign Criteria for Nuclear Power Plants," January 1, 1981.
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s Appendix A:
Information Required for Phase !! & !!!
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_(f For Phase II and III of this study the ability .to detect steam leaks in the HPCI. and RCIC rooms by temperature sensors w examined. Recommendations for temperature detector setpoints and locations will be provided in the report.
Before this work can commence, additional information is recuired.
This information is needed to model the compartment's themedycami response during a steam leak in the HPCI or RCIC rooms.
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Free air volume of the rooms From the drawings sent to General Electric in Reference 1
. an estimate can be made of the floor area of the HPCI and
' .RCIC rooms. However, insufficient data is given to determine the - air volume of each room. If these volumes are not readily available, then more drawings are needed to describe the height of the rooms as well as the volumes of pipes and pumps within the rooms.
- 2. Flow area out of rooms
.l Further data or drawings are needed to describe flow passages out of the rooms. This includes blowout panels or any doors which are not expected to survive small pressure differences ( 1 psig).
- 3. Surface area and material inside rooms )
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To correctly model the heat transfer between the air and the rooms' equipment and walls, the wall and equipment surface areas must be known. In addition, the material composition (i.e. concrete, steel, etc) is needed. As with the other data if the information is not directly
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Ambient conditions in rooms The normal and. extreme temperature, pressure, and humidi-
~ty in each room is required.
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- 5. Fire Protection Further information is needed _on the fire protect 4cr system concerning the number of temperature sensors anc the control logic of the system.
1 6 ., Sumps -
The presence of sumps in either room needs to be de-scribed. This includes capacity, pump rates, and iso-lation setpoints.
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