ML20005B521
| ML20005B521 | |
| Person / Time | |
|---|---|
| Site: | Fort Calhoun  |
| Issue date: | 02/18/1981 |
| From: | Gollob R, Mills R, Worley C ABB COMBUSTION ENGINEERING NUCLEAR FUEL (FORMERLY |
| To: | |
| Shared Package | |
| ML20005B513 | List: |
| References | |
| TASK-2.B.1, TASK-TM 8879-PE-SD07, 8879-PE-SD7, TAC-44374, NUDOCS 8107080327 | |
| Download: ML20005B521 (16) | |
Text
.
Enclosure (1) to CE-18074-940
)
SYSTEM DESCRIPTION FOR REACTOR COOLANT GAS VENT SYSTEM FOR OMAHA PUBLIC POWER DISTRICT FORT CALHOUN UNIT NO. 1 8879.;PE-SD07
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Revision 00 Nuclear Power Systems COMBUSTION ENGINEERING, INC.
Windsor, Connecticut This document is the property of Combustion Engineering, Inc. (C-E)
Windsor, Connecticut and is to be used only for the purposes of the agreement with C-E pursuant to which it is furnished.
Prepared by: rk.-Na ScIN-Date: N/'//8/
Co nizant Engineer Y@U Approved by:
- M Date:
Supervisor Approved by:
M((
Date:.2
/pf Project Manager
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Ir. sue Date: 2 flS 81 l
QA Status: Verified l
The safety related design information contained in this i
document has been reviewed and satisfies, t.t e., :.;.;:'.c.!:4.a:.ta.m.
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I 8107080327 810701 pag G/S/fri PDR ADOCK 05000285 eP ppg Document Rev. No.
C' W
RECORD '0F REVISIONS No.
Date Para. Nos. Involved Prepared by Approvals
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R. B. Gollob C. A. Worley R. R. Mills
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8879 - PE-SD07 ' Rev.00 Page 2 of 15
Table of Contents Page Section Title No.
1.0 PURPOSE 4
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2.0 SCOPE 4
3.0 REFERENCES
4
- 4. 0.
SYSTEM FUNCTIONS 4
5.0
SUMMARY
SYSTEM DESCRIPTION 5
6.0 COMPONENT DESCRIPTION
- 6 7.0
' OPERATION 6
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6 7.1 Normal Operation 7.2 Operation During Plant Accident 7
Conditions 7.3
. Maintenance 8
8.0
. SAFETY EVALUiTION
-8 TABLES Table 1 Major System Valves 9
FIGUR?S Figura 1 H Flowrates to Containment 10 2
4 Figure 2 Vent Duration to Containment 11 APPENDIX Appendix A Sumary of Definitions and 12 Abbreviations Appendix B RCGVS Failure Mode Effects Analysis 13 8879.-PE-SD07 Rev.00 Page 3 of 16
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1.0 PURPOSE The purpose of this document is to provide a general description of the Reactor Coolant Gas Vent System (RGGVS), including system function.
major parameters, and operation.
2.0 SCOPE This document serves to provide orientation to the system and a summary of its components and their uses.
A detailed description of components, process data, and operation is not intended.
Process and component data contained herein is of an explanatory nature; it is not to be used for the design of connecting systems or components.
Components and process detail will be found in the referenced documents
,,,and in subsequent equipment documents, operating guides, etc.
3.0 REFERENCES
3.1 P&ID
- 1. Reactor Coolant Gas Vent System, E-8879 -310-107 3.2 Procedural Guidelines for Reactor Coolant Gas Vent System for Fort Calhoun, Unit No. 1, 8879-PE-PR07
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4.0 SYSTEM FUNCTIONS 4.1 Remotely Vent Gases From Reactor Vessel Head and Pressurizer Steam l
. Space l
The Reactor Coolant Gas Vent System is designed to be used to remotely vent non-condensible gases from the reactor vessel head and pressurizer steam space during post-accident situations when large quantities of non-condensible gases may collect in these high points.
The purpose of venting is to prevent possible interference with core cooling.
Small amounts of gas can be vented to the quench tank (QT) and thus not enter the containment atmosphere.
Larger volumes will require venting directly to the containment where the hydrogen concentration will be controlled by the containment hydrogen purge system.
Pressure instrumentation is included in the design to monitor system leakage during normal plant operation.
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8879 -PE-SD07 Rev.00 Page 4 of 16
+
e 4.2
. Aid in RCS Venting Procedures Following a Maintenance Outage Although' designed'for' accident conditions, the system may be used to aid in the pre-or post-refueling venting of the raactor coolant system.
Venting of the individual CEDMs and RCPs will still be necessary; however, pressurizer and reactor vessel venting can be accomplished with the system if desired.
Vent flow would be di.rected to the QT for this operation to prevent inadvertent release.of radioactive fluid to the containment.
5.'O
SUMMARY
DESCRIPTION 5.1.. -System Parameters Flow >100 scfm H, dependent upon RCS pressure and 2
temperature 0
Design Temperature 700 F Design Pressure 2500 psia l.ine Size 1"
5.2 Description Summary The system is designed to permit the operator to vent the reactor vessel head or pressurizer steam space from the control room under post-accident conditions, and is operable following all design basis events except those requiring evacuation of the control room or a complete loss of all AC powe,r.
The vent path from either the pressurizer or reactor vessel head is single active failure proof
. with active components powered from emergency power sources.
Parallel valves powered off alternate power sources are provided at both vent s
sources to assure a vent path exists in the event of a single failure of either a valve or the power source.
The system provides a redundant vent path either to the containment directly or to the QT. The QT route allows removal of the gas from the RCS without the need to release the highly radioactive fluid into containment.
Use of the QT provides a discharge location which can be used to store small quantities of gas without influencing containment hydrogen concentration levels.
However, venting large quantities of gas to the QT will result in rupture of the QT rupture disc providing a second path to containment for vented gas.
Cooling of gas vented to the QT is provided by introducing the gas below the QT volume. The direct vent path is located to take advantage of mixing and cooling in the containment.
8879 -PE-SD07 Rev.00 Page 5 of 16
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As shown on the P&ID, (Ref. 3.1), non-condensible gases are removed
.from either the pressurizer or reactor vessel through the flow restrict-ing orifice and one of the parallel isolation valves and delivered to the QT or containment via their isolation valves.
Venting under accident ccnditions would be accomplished using only one source (reactor vessel or pressurizer) and one sink ('QT or containment) at a given time.
6.0 COMPONENT DESCRIPTION There are no major components in the RCGVS.
6.1... Piping and Valve's t
All piping and valves used in the RCGVS are either type 304 or type 316, austenitic stainless steel or equivalent.
Socket welded connections are used throughout except where disassembly for maintenance, particularly refueling operations, is required.
The system is designed for 2500 psia and 7000F and is compatible with superheated steam, steam / water mixtures, fission gas, helium, nitrogen and hydrogen.
A 7/32 x 1" stainless steel flow restriction orifice is provided in each vent path to limit reactor coolant leakage to less than the capacity of.'one charging pump in the event of a line break or inadvertent operation. A list-ing' of the major system valves is provided in Table 1.
6.2 Instrumentation 6.2.1 Pressure indication in the vent line downstream of the reactor vessel head and pressurizer isolation valves is provided to detect leakage past any of these valves during normal power operations and alarm to alert the operator of the leakage.
This instrument is not re-quired to function during post-accident conditions and is therefore not provided with emergency power.
6.2.2 Open/close position indication for all remotely operated solenoid valves
.is provided in the control room.
7.0 OPERATION 7.1 The RCGVS is not used during normal power opc*ations.
All remotely operated valves are administrative 1y controlled in the control room to assure the system is used only when necessary under accident con-ditions.or in conjunction with RCS venting procedures associated with maintenance as discussed in Section 4.2.
Pressur e instrumentation is provided to detect leakage pass the first isolation valves.
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8879'-PE-SD07 Rev.00 Page 6 of 16 l
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7.2 Post-Accident System Operation In the unlikely event that an accident results in the generation of significant quantities of non-condensible gases within the RCS, the RCGVS is used to remove the gases from the RCS.
Pr.ior to operation of the system, the quantity of non-condensible gases that may be present in the RCS must be estimated.
This is accomplished through reactor vessel level indication for the case of gas bubbles in reactor vessel and by the response of system pressure control methods or departure from saturation conditions in the pressurizer for the case of gas in the pressurizer. Plant operating guidelines (Ref. 3.2),
, provides detailed instructions concerning the detection of the presence of non-condensible gas and the approximate volume of the gas.
If it is determined that a gas bubble exists in either the reactor vessel or the pressurizer and administrative approvals to operate the RCGVS are obtained, the system is placed in operation as follows:
A. Administrative controls are removed from control room panels.
B. The vent flow rate will be dependent upon reactor coolant system temperature and pressure.
Flow rates for non-condensible gas (hydrogen) from the reactor vessel are provided in Figure 1.
With the bubble size estimates and the flow rate, a venting duration can be determined.
Figure 2 provides vent durations for various initial con-ditions.
Plant operating guidelines (Ref. 3.2) con-tains detailed instructions concerning the detennination of the duration of venting.
C. The vent system is aligned to vent from the pressurizer or
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~ reactor vessel to the containment or pressurizer quench tank.
Small quantities of gas may be vented to the OT without rupture of the OT rupture disc.
Larger quantities of gas are vented directly to containment; containment H2 i
concentration should be monitored and controlled with the hydrogen purge system.
Valve position indication is provided to' ' monitor valve operation.
D. Venting is terminated after the previousky determined time interval.
If necessary, the bubble size is re-estimated and the venting re-established as of ten as necessary.
After system operation has been completed, adminstrative controls are again implemented to preclude operation.
8879.-PE-SD07 Rev.00 Page 7 of 16
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.u 7.3 System Maintenance and Inspection 7.3.1. Required maintenance is limited to ' inservice inspection of the' Class 2
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solenoid valves required by Section XI of the ASME Code.
Drains have been provided for this purpose.
7.3.2 The system will have to be partially disassembled each refueling to allow head removal.
A removable spool-piece has been included in the design for this purpose.
7.,3.3 Operability of each valve should be checked and recorded during each
.- - refueling to confinn system operability.
8.0 SAFETY EVALJATION 8.1 Performance The RCGVS may be required to operate durin9 post-accident situations to remove non-co'
'sible gases from the RCS.
To assure operability under those cond c.1s, the components of the system. required to perform venting operations have been designed to operate under post-accident environmental conditions.
They are provided with. emergency power sources.
The system is Safety Class 2, Seismic 1.
Parallel valves assure a vent flow path to containment in the event of single active failure. Series isolation is provided in the event that a vaive does fail to close.
i The RCGVS is not required to operate during normal power operat ot.
To pre:lude inadvertent operation of the system, valves are subject to administrative controls prior to placing the system in operation.
Should inadvertent operation occur, a flow limiting orifice is pro-vided to limit mass loss from the RCS to less than the~ capacity of a single charging pump.
8.2 Failure Modes and Effects
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Appendix B provides the failure modes and effects of those failures upon the RCGVS.
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8879 -PE-SD0; Rev.00 Page 8 of 16
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t' Table 1 Major System Valves Valve Number R.V-101, 102, 103, 104, 105, 106 s
Valve Type Globe
. Operator
' Solenoid,,
Design Pressure 2485 psig' Des'ign Temperature 700 F 0
Operating Environment Contai nent: Normal, LOCA, Main Steamline Break Seism.ic Class 1
Safety Cl?.ss
-.~2 Design Code ASME Code Section III, Class 2 "
Electrical Class IE Active (yes/no)
Yes Fail Position Closed.
' Limit Switch Position Yes (open, close)
Indication Body Material Stainless Steel Leakoff Packless 8879.-PE-SD07 Rev.00 Page 9 of 16
FIGURE 1 HYDR 0 GEN (REACTOR) 8 ITI 0
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T = 400 F
-8 2500 T - 550 F
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T - 700 F 2000
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T - 250 F
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1000 w
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500
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1000 2000.
3000 4000 g-FLOWRATE, SCFM
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FIGURE 2 VENT DURATION OF HYDROGEN vs RV
. TEM P.
AT P = 2250 PSIA M.
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VB - Bubble Volume 30 3
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100 200 300 400 500 600 700 RV.. EMPERATURE, U ~
F 8879 -FE-SD07 Rev.00
' Page 11 of 16
Appendix A Summary of Definitions & Abbreviations 1.0 DEFINITIONS COMPONENT CLASSIFICATIONS Safety Class:
As defined in ANSI N18.2 except for Safety C1. ass 4 which is defined as Quality Group D in Reg. Guide 1.26.
Mechanical Code Class: ASME pressure vessel code or other
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Seismic Category:
As defined in NRC Reg. Guide 1.29 Active /Non-Active Component:
As defined in Reg. Guide 1.48.
Class I Electrical:
As defined in IEEE 308 2.0 ABBREVIATIONS Reactor Coolant System
- 1. SYSTEMS:
- RCS, RCGVS - Reactor Coolant Gas Vent System
- 2. EQUI? MENT:
CRDM Control Rod Drivc Mechanism Reactor Coolant Pump RCP
' Quench Tank QT 8879 -PE-SD07 Rev.00 Page 12 of 16
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Appendix B RCGVS Failure Modes Effects Analysis 8879 -PE-SD07 Rev.00 Page 13 of 16
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d F.iilute Hodes Eff'ects Analysis for the Reactor Coolanti Cas' Vent System Renarls i
b Symptois.ind Local Elfccts Mattiod of Inhorant Compensattag and echt yng1 Effects
@ y,;
- Detection Provision y3mo_
_ Ho
. Cause inclu.Itne Dependent Fa11bres_
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- 3 d7 Fosition Indica.
False indication Electro-Lorm of ability to detect Fressure gauge None l
ter for RV-101, of valve position mechanical valve psoitton in reactor vessel (P-138) inpica-E 102 failure.
vent line.
tion shows valve.
R la opened.
8 Fosition I'ndica-False indication Electro-Loss of ability to detect valve Pressure gnugt None tor for RV-103.,
of valve position sicchanical posittoa in pressurizer vent (p-138). Indica-104 failus s.
line.
tion shnus valve,
is opened.
s 9
Fosition Indica-False indication Electro-14ss of ability to detect valve.
Quencli Tenk None tor for RV-105 et valve position mechanical position in quench tank vent temperature and failure lino.
pressure verify value position.
Pressure gaug;o i
(P-138).
10 Position Indica-False indication Electro-1.oss of ability to detect Containment pressure /
None tor for RV-106 et valve position
- mechanical valve position in containment humidity / radiation failure vent line.
Icvels verify con-tainment valve position.
Pressure gauge (F-138).
11 Drain Valves a.
Seat Leakage Contamination, No impact on system operation.
None Drain l'ines*are*
RV-200, 203 Hechanical blind flanged.
204-damage
.Faite Closed Hechanical No impact on normal operations.
Operator None b.
Binding Inability to drain af fected
,, line section.
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- pdFfWe' Hides Ef,[;rcts An-lyste far the R'wctre Cowlent C9 V*nt Syst33, Reu tk s
Heth14 cf Inh:rN.t Coopersitirag cnd 9the F;iltra Symptoms cnd 1.ccs1 Effsetc N ).
Name
- H:d2 Cruze includinnDependentFailurss Detectitn Fr*visten Ef Lvit e_
b.
Fails closed Mcchanical No impact on normal operation.
Volvo position None Venttog.to Failure. Imes Innb111ty to vent pressurizer or indication in the the quecch to
- of Power to reactor to containment.
control room.
tank if posa
[D the Valve Operat'r.
sible,1f o
y to necessary.
h3 "Pressuriser a.
Faila Open Hechanical No impact on nnrmal operation.
Valvo position None RedunJJnt g
p Vent Isolation,
Dinding. Seat inability to vent the reactor indicotton in isolation Valve RV-103 Leakago vessel wittout also venting control room.
values to mg 104 pressurizer. This is satisfactory F-138 h1ch presa containrant w
and will*not impact natural aura indication.
(RV-106),
circulation, and quench n
t a n*a (RV.IO1 prectu cs a
un.ontrolled verting of the pressurt a e r.
b.
Falle Closed Hechanical
~ Inability to vent the pressuriser.
Valve position in Farallel redundant Parallel Failure. I,oes the control room.
1 solation valve.
Isolatten of Power
, Isolation valve.
valve allow; Operator.
venting of the pres-surl er.
No impact on normal operation.
Valve position
.None.
RcJurJant 6
Reactor vessel a.
Faila Open Mechanical Yeat Isolation Binding. Seat 11nable to vent pressuriter without indication in the isolation Valve RV-101, Leakage also venting 'the Reactor Vessel.
control room.
vali.cs to 102 This is satisfactory and will P-138 high pressure con t a in.sen t not impact natural circulation.
Indication.
(RV-106) and (RV-IC5) precludes uncontrolled ventina of the reactor vessel.
).
Fails Closed Hechanical' Inability to vent the reactor Valve position in.
Parallel redundant Parallel Failure. tera vessel.
the control room.
teolation 4sive.
1 solation of Power Ope r's tor.
valve allevs
. venting of the reactor
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e Failure Modes Ef fec'te Analysis for_the Renetor Coolant Cas Vent System _
Nethod of Inherent Coopensating
. and other Symptomp and Local Effects
- Deteetton__
_ tg, ovis,1g,n
__ tf feety
' Failure w
Hede __
cause includi e De e dent Failures _
Fest-AccidenIL.
i Frissure Indicator
- a. spurious high Elec'tro-No la pact on ner,ul operation.
Walvo position None
__ amo venting in.
y pressure indica-mechanical
, Loss of ability to detect Icakage
- indication la the not affected, into thu vent system piping.
co,ntrol toon.
g tion / alarm failure, set-co. 7,
- b. spurious lov Electro-No imp.nct on nnrsal oporation.
Valvo position None Post-Acc1Jent potut drift y
vintis.g is not M
pressure indica-mechanical Los:s of ability tu detect leakago indication in the a
afftted tion failure, set-into the vent system piping.
control cosa.
point drift Redundant isola
&chanical Inability to isolate quench tank valve'pssation indi.
None a
tion valves to o-t%
Quinch Tank Isole-
- a. Falls open
!tira valve RV-105 Binding. Seat f rom the readtor cool. int gas vent cation 1.- the contret the reactor
- room, Leakage system.
vessel and pres.
c, Q
suriser precluda uncontrolled ven' o
Ingtothequencf O
ten 4
'b.Failsclosed Hechanical No impact on norw l operation.
Valve position indi.
None Venting to the*
Failure, Loss Inability to vent pressuriser or cation in the contro1 containn<nt is of Fouer
~. reactor to quench tank.
room. Operator.
possible,'il necessary.
3 Fr:ssure Instrv-
- a. Fails Open Hechanical None Operator
- 1tedundant cent Isolation Binding. Seat Yalves Valves RV-201, Leakage 202
- b. Fails closed Hechanical Loss of ability to, detect seat Operator Fone Unlikely irvent Failure leakage f rom the pressuriser add since valve is
- normally open reactor isolation valves into the reactor coolant gas vent system and has only a P ping.
manualopera i
n 4
Crntainment
- a. Fails Open Hechanical Inability to isolate reactor coolant High containment prosaure None Redundar.t isola-tion '41'**
Isalation valve Binding, Seat vent system from containment.
,and humidity if venting is IV-106
- Leakage in progress. Valve posities
,the reacter indication in the control vessel and pres-uriser preclude
%nconts ;;4d ing to the containment.
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