ML20207P993
| ML20207P993 | |
| Person / Time | |
|---|---|
| Site: | Fort Saint Vrain  |
| Issue date: | 01/13/1987 |
| From: | Holmes M, Johns J, Moffette J PUBLIC SERVICE CO. OF COLORADO |
| To: | |
| Shared Package | |
| ML20207P988 | List: |
| References | |
| P-87002, TAC-63576, NUDOCS 8701210018 | |
| Download: ML20207P993 (32) | |
Text
W ATTACHMENT 4 TO P-87002 SAFETY ANALYSIS REPORT FOR TECHNICAL SPECIFICATION LC0 4.3.1 CHANGE PERMITTING SAFE SHUTDOWN COOLING WITH EVAPORATOR-ECON 0MIZER-SUPERHEATER FORT ST. VRAIN NUCLEAR GENERATING STATION DOCKET 50-267 PUBLIC SERVICE COMPANY OF COLORADO Prepared By:
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' Attachment 4 to P-87002 Page 2 TABLE OF CONTENTS Page I.
IN'TRODUCTION AND
SUMMARY
.................................... 4 II. BACKGROUND.................................................. 6 II.1 FSAR Description'of Safe Shutdown Cooling..............
6 II.2 Safe Shutdown Cooling on Reheater (30-Minute Delay)......................................
8 II.3 Safe Shutdown Cooling on EES With Delay Extended to 1-1/2 Hour................................ 8 II.4 Addition of HELB to Safe Shutdown Cooling Cases..........................................
9 II.5 Safe Shutdown Cooling on Reheater (1-1/2' Hour Delay).................................... 9 II.6 Safe Shutdown Cooling With EES From 105% Power.............................
10 I I I. SA FETY ANAL YS I S.............................................
12 III.1 Description of Safe Shutdown Cooling With EES.......
12 III.1.1 Safe Shutdown Cooling Following a HELB Accident...............................
12 i
L III.1.2 Safe Shutdown Cooling Following a Seismic or Maximum Tornado Event...................
14 l
l-III.1.3 Safe Shutdown Cooling With Single Failures in Cooling Water Supplies.........
14 L
III.1.4 Transient Analysis of Safe Shutdown Cooling With EES from 87.5% Power.
15 III.2 Comparison' of the EES Cooldown with Regulatory Requ i rements.............................
17 III.2.1 Comparison with PWR Auxiliary l
Feedwater System...........................
17 III.2.2 Comparison of EES Cooldown with General Design Criteria...............
18 IV. R E FE R ENC ES................................................. 21 l
L
=
- 0) -
to P-87002 Page 3.
TABLES Page III Single Active Failures Assumed Coincident with HELB That Require Manual Action Within Turbine Building............................... 23 III-2 Summary of Forced Circulation Cooling-
-Redundancies...........................................
24 III-3 Effect On NRC Requirements Of The Deletion Of Reheaters From FSV Safe Shutdown Cooling...............
25 FIGURES II-1 Schematic Flow Diagram: Cooling With Safe Shutdown Equi pent (Adapted From FSAR Figure 10.3-4)
III-I Schematic Flow Diagram: Firewater Flow Path For Safe Shutdown Using the EES Section III-2 Maximum Fuel Temperature During Safe Shutdown Cooling With Firewater From 87.5% Power Using EES
'III-3 Primary System Pressure During Safe Shutdown Cooling With Firewater From 87.5% Power Using EES III -Steam Generator Hot Module and Average Module Inlet Helium. Temperature During Safe Shutdown Cooling With_ Firewater From 87.5% Power Using EES f
to P-87002 Page 4 I. _ INTRODUCTION AND
SUMMARY
Public Service Company of Colorado (PSC) reported to the NRC in LER 86-020 (Ref. 1) that the Fort St. Vrain (FSV) FSAR discussion for " Safe Shutdown Cooling," following a 1-1/2 hour Interruption of Forced Cooling (IOFC) and using firewater to one steam generator reheater section, may be invalid (see FSAR Sections 10.3.9, 10.3.10, and 14.4.2.2).
Since that time, PSC has performed additional analysis which have confirmed the preliminary conclusion that one reheater is inadequate to provide Safe Shutdown Cooling with firewater following a 1-1/2 hour IOFC from 105% reactor power. Subsequent to the 105% power analysis, one reheater supplied with G rewater has been confirmed to be adequate for cooldown following a 1-1/2 hour 10FC from reactor power levels up to approximately 39% (Ref. 2).
One of the " Corrective Actions" commitments in LER 86-020 was to investigate a change in the licensing basis that would delete the reheaters as an optional method for Safe Shutdown Cooling. This safety analysis report summarizes and evaluates the results of that investigation.
As part of this investigation, an analysis was performed of Safe Shutdown Cooling with firewater using one EES section from 105 percent _ power after a 1-1/2 hour 10FC. This resulted in 2.7 percent of the fuel exceeding 2900 degrees F, with a maximum fuel temperature of 3024 degrees F (Ref. 3).
The FSAR analyses conservatively assume that fuel temperatures must be-maintained below 2900 degrees F,
a temperature well below that at which rapid fuel deterioration is anticipated (above 3400 degrees F).
Discovery that fuel temperatures cannot be maintainad below 2900 degrees F is considered to be a condition outside the present licensing basis, and was the cause for submittal of LER 86-026 (Ref. 4).
As committed in LER 86-026, reanalysis of Safe Shutdown Cooling utilizing one EES Section has now been completed as necessary to support a gradinted rise-to-pcwer program based on an acceptable cooldown of the plant for the reicvant accident scenarios and proposed reactor power limit. The reanalysis has been submitted to the NRC for review (Ref. 5), and is summarized herein (see Section 111.1.4). These reanalyses determine the consequences of Safe Shutdown Cooli.g fellowig a bl/2 hour 10FC from a reactor power level of 87.5%. Tais is based on firewater supplied to one EES section during Safe Shutdown Cooling accident conditions (including maintaining subcooled conditions for the secondary coolant at the steam generator outlet). This analysis has shown that Safe Shutdown Cooling with one EES section supplied with firewater following-a 1-1/2 hcur 10FC can be performed from reactor power levels up to 87.5% without exceeding a fuel temperature of 2900 degrees F, and without exceeding allowable,
temperature or stress limits of the heat exchangers or circulators (Ref. 5).
The two steam generator economizer-
i to P-87002 Page 5 evaporator-superheater (EES) sections are shown to provide sufficiently redundant means of Safe Shutdown Cooling, ::uch that the (backup) reheater cooldown option for Safe Shutdown Cooling can be deleted from the licensing basis for FSV, and in particular, from the Technical Specifications (LC0 4.3.1).
i As a result, in order to ensure adequate capability for Safe Shutdown Cooling and other abnormal events, PSC has proposed changes to LC0 4.3.1 that require both evaporator-economizer-i superheater (EES) sections and both reheater section's be available during operation at power as the minimum number of operable heat exchangers.
The FSV Technical Specifications currently require both the reheater section and the EES section of one steam generator and either the reheater section or the EES section of the other steam generator. The Basis for [C0 4.3.1 will be revised to state that the reheater sections are capable of providing cooling for other abnormal events, but are not relied upon to provide Safe Shutdown Cooling.
A second proposed change to LC0 4.3.1 is that the EES sections shall be capable of receiving water from both the Emergency Condensate Header and the Emergency Feedwater Header instead of the former minimum aTT6wable of only one of these emergency headers.
Although the EES sections can be supplied water from both the Emergency Condensate Header and the Emergency Feedwater Header, only one of the two headers is needed to supply the required cooling water for Safe Shutdown Cooling. The reheaters can be supplied with water from the Emergency Condensate Header, but not from the Emergency Feedwater Header.
Reliance on the EES sections continues to ensure that the FSV Safe Shutdown Cooling method meets all of the NRC regulatory requirements and protects the public health and safety. This analysis is discussed in detail in Section III.
to P-87002 Page 6 II. BACKGROUND The purpose of Section II is to provide a summary of the historical background leading up to the current status of the analyses of Safe Shutdown Cooling capabilities of an evaporator-economizer-superheater (EES) section and of the reheater section of one of the two steam generators. This starts with: (1) the FSAR discussion of Safe Shutdown Cooling with the EES, (2) the reheater cooling with a 30-minute delay, (3) t'ES cooling with delay extended to 1-1/2 hours, (4) the recent EQ requirements of High Energy Line' Breaks with consequent constraints on access-to the building for valve manipulation, (5) the recent analyses of reheater-cooling with a 1-1/2 hour delay, and (6) the recent reanalysis of EES cooling from 105% pcwer. The accumulations of more restrictive requirements is shown to require the omission of the reheater option for Safe Shutdown Cooling and to require a reduction in the operating reactor power level from 105% to 87.5%
as the maximum power frorn which Safe Shutdown Cooling can be initiated using one EES section supplied by firewater after a 1-1/2 hour interruption of forced circulation (IOFC).
The following Section III shows there is adequate redundancy without relying on reheaters for Safe Shutdown Cooling.
The reheater sections are capable of providing cooling for other abnormal events, but are not relied upon to provide Safe Shutdown Cooling.
II.1 FSAR Description of Safe Shutdown Cooling.
The Fort St. Vrain Final Safety Analysis Report (FSAR) evaluates shutdown cooling capabilities for various postulated accident conditions.
These accidents are typically analyzed considering their effect on primary and secondary heat removal capabilities.
The most limiting analysis for those accidents considered to be credible is identified as Safe Shutdown Cooling as a consequence of a Design Basis Earthquake (DBE, also called Safe Shutdown Earthquake) or Maximum Tornado (FSAR Section 10.3.9). These Safe Shutdown Cooling accidents are considered to combine the loss of outside electric power; main turbine trip; and loss of the deaerator, all three boiler feed
- pumps, condensate pumps, auxiliary and backup auxiliary boiler feed pumps, the main condenser and both main and service-water cooling towers.
Under these corditions only equipment on the " Safe Shutdown List" (summarized in FSAR Table 1.4-2) is available to be utilized, including the firewater system which is relied upon to provide secondary heat. removal and helium circulator motive power, while the service water system provides coolant to the essential equipment required to operate during Safe Shutdown Cooling with firewater. The limiting analysis conservatively assumed a 1-1/2 hour delay in restoring forced circulation due to postulated failures of non-safety related piping requiring inspection, manual isolation and alignment of the firewater cooling flow path.
Restart of forced circulation using only Safe Shutdown List
to P-87002 Page 7 equipment following a 1-1/2 hour delay is evaluated in FSAR Section 14.4.2.2.
Figure II-1 (adapted from FSAR Figure 10.3-4) shows a simplified schematic flow diagram for the use of firewater for Safe Shutdown Cooling as detailed in the above FSAR sections. As shown in the figure, either the engine-driven or the motor-driven firewater pump can supply either the Emergency Condensate or Emergency Feedwater Headers.
The Emergency Condensate Header can supply either the EES sections or the reheater sections of the steam generators.
The Emergency Feedwater Header can supply only the EES sections. Both lines supply circulator motive power via the emergency water booster pumps to a circulator water turbine drive.
In the FSAR (Sections 14.4.2, 10.3.9, and 10.3.10) discussions of Safe Shutdown Cooling, the Design Basis Earthquake (DBE, also called " Safe Shutdown Earthquake") and Maximum Tornado accident conditions are described to be causes for initiation of Safe Shutdown Cooling. A third potential initiating cause of Safe Shutdown Cooling is a High Energy Line Break (HELB), discussed in detail in FSAR Section 1.4 and Appendix I.
The details of cooldown following a HELB using only Safe Shutdown equipment under the current Equipment Qualification (EQ) guidelines are not currently described in the FSAR, but are discussed in later sections of this report.
(The several redundant EQ qualified and non-EQ qualified flow paths for cooling are described in general terms in FSAR Appendix I.2.)
In both the DBE and the Maximum Tornado cases, personnel access was assumed to be possible to both the Reactor and Turbine Buildings immediately after the event. Thus manual operation of valves can be readily achieved, which can alleviate any single active failure. A passive failure of a f
seismically qualified line or valve can be circumvented by the use of another seismically qualified line.
For these conditions, Safe Shutdown Cooling with firewater is shown to be single-active or single-passive failure proof in FSAR Section 10.3.10, which describes Safe Shutdown Cooling with single failures in cooling water supplies (discussed in more detail in Section'III.1.3 of this report).
In the FSAR discussions of Safe Shutdown Cooling, the 4
emphasis is on the use of the EES Section of a steam generator to provide the heat transfer surface from the primary coolant helium gas to the secondary side water.
The results of the analyses presented in FSAR Section 14.4.2.2 I
are for the EES cases. No analysis for the cooldown using firewater following a 1-1/2 hour delay and using the reheater section of a steam generator is presented in the FSAR. However, in FSAR Section 10.3.10 there is a statement
.~
to P-87002 Page 8 which asserts that the Safe Shutdown Cooling after a 1-1/2 hour 10FC is possible using a steam generator reheater section instead of an EES section.
(See Section II.5 for recent analyses of reheater cooling after a 1-1/2 hour 10FC).
II.2 Safe Shutdown Cooling on Reheater (30-Minute Delay)
In September 1974, as documented in the Original FSAR Section 14.4.4.2 in a revision dated December, 1974 (Ref.
6), an analysis was performed which determined the effects of a cooldown following a Design Basis Earthquake or Maximum Tornado event from 105% power utilizing a steam generator reheater section supplied with firewater.
This analysis assumed that there was a 30-minute delay following the event before firewater cooling was initiated through the reheater section of a steam generator with one circulator operating also on unbocsted firewater. The analysis took credit for
]
the residual water inventory in the EES tube bundles in determining steam generator cooling capacity.
The results of' this analysis indicated that one reheater module of a steam generator was capable of removing the core decay heat when sup with firewater and with only one module flooded (plied there are 6 modules per steam generator).
(Refs.
6, 7, and 8).
An examination at that time of these results indicated that the EES tube temperatures in the five inactive and uncooled EES sections and the circulator inlet temperature did not exceed the allowable temperature limits.
(Inactive and uncooled EES sections are those EES sections in the steam generator modules whose upstream reheater modules are not flooded and therefore the helium is not cooled prior to the gas passing over the EES sections in those modules).
This information was not documented in the FSAR.
The FSV emergency procedures are currently written to make the EES Section the preferred cooldown mode, with reheaters as a backup.
II.3 Safe Shutdown Cooling on EES With Delay Extended to 1-1/2 Hours In 1978, the interruption of. forced circulation cooling (I0FC) following a seismic event was required to be extended from 30 minutes to 1-1/2 hours to allow time for the operators to inspect piping and perform the necessary valve lineups prior to restart of forced circulation (Ref. 9).
The analysis for the 1-1/2 hour 10FC was performed for the case where firewater is supplied to the EES, the preferred method for cooldown. This is the case described in the Updated FSAR Section 14.4.2.2.
The situation where l
firewater is supplied to the reheater after the 1-1/2 hour delay was not analyzed at that time.
to P-87002 Page 9 II.4 Addition of HELB to Safe Shutdown Cooling Cases A third initiating cause of Safe Shutdown Cooling has been added. That is the group of postulated accidents classed as "High Energy Line Breaks" (HELB).
PSC is currently completing an extensive program to environmentally qualify the electrical equipment required for Safe Shutdown following a HELB in the Reactor or Turbine Building.
This program ensures that the Safe Shutdown equipment is in compliance with the requirements of 10CFR50.49.
The Safe Shutdown Cooling flow path following a HELB is not currently clearly identified in the FSAR, but would be generally as described in Sections 10.3.9, 10.3.10 and 14.4.2.2.
(See Fig.
III-1 and Section III.1.1 for a description of Safe Shutdown Cooling during a HELB).
Contrary to the wording currently in 10.3.10, the reheaters will not be relied upon in the future as a backup to the EES for Safe _ Shutdown Cooling, as discussed in detail below.
When the completed EQ program has been approved by the NRC, the descriptions in appropriate FSAR Sections (e.g.,
1.4.5, 10.3.9, 10.3.10, 14.4.2.2, and Appendix I.6.2) will be updated as appropriate.
II.5 Safe Shutdown Cooling on Reheater (1-1/2 Hour Delay)
As a result of the current HELB analyses, a Safe Shutdown Cooling case was recently analyzed in which only one reheater module (out of the six modules in a steam generator section) was utilized in a firewater cooldown following a 1-1/2 hour 10FC from the 105 percent power condition. This is an extension of the 30-minute delay case run in 1974 (see II.2 above). Due to the relatively small surface area of a single reheater module, the heat removal capability of one reheater module cooled by firewater was found to be inadequate to remove the cumulative 1-1/2 hours of stored decay energy plus the 105% equilibrium core decay heat generation rate continuing after 1-1/2 hours.
This was reported to the NRC via Licensee Event Report 86-020 (Ref.
1). The results of the above analysis shtws that initially upon restart of helium circulation the primary coolant temperature is in excess of 1400 degrees F.
It was found that these temperatures exceed allowable temperatures for the steam generator EES tubes in the unflooded modules. The inlet temperature into the helium circulator also exceeded 1200 degrees F,
which was the allowable circulator temperature based on the assumptions used in the original FSAR analysis.
A subsequent study has been made of the FSV circulator operating limits related to the helium temperature passing through the compressor blading (Ref.
19).
This study indicates that the temperature of the circulator blading
.to P-87002
-Page 10 material may be. allowed to exceed 1200 degrees F and approach 1300 degrees F for up to 100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br /> while operating at the. low circulator speeds as would be used during Safe Shutdown Cooling.
One of the Corrective Action commitments in Ref. I was to perform an analysis to determine the maximum power - level from which the reheaters remain viable as a Safe Shutdown Cooling option (following a 1-1/2 hour 10FC), which could be used_ to justify operation below this power level for an interim period. This analysis has now been completed, and the results were submitted separately to the NRC (Ref. 2).
The maximum power level from which reheater Safe Shutdown Cooling can be performed (following a 1-1/2 hour 10FC) was found to be approxic.ately 39%.
II.6 Safe Shutdown Cooling With EES From 105% Power
(
The transient analysis results for the Safe Shutdown Cooling case presented in FSAR Section 14.4.2.2 have recently been reanalyzed (Ref. 3).
This was based on a 1-1/2 hour interruption of forced circulation cooling (I0FC) before restart of cooling with fire water, using one EES.
Infinite operation at 105% rated power prior to the accident is a basic assumption of this FSAR analysis.
The accident conditions of FSAR Sections 10.3.9 and 14.4.2.2 are the most limiting of the postulated interruptions of forced cooling (1-1/2 hours) involving Safe Shutdown using one steam generator EES section and one helium circulator on Pelton-wheel drive.
This recent reanalysis, based on adjustment of primary flow to maintain secondary coolant outlet temperatures below 300 degrees F, shows that there is no effect on primary coolant boundary integrity, and that about 2.7% of the core will exceed 2900 degrees F, with a maximum temperature of 3024 degrees F (Refs 3 and 18).
FSAR analyses conservatively asseme that fuel temperatures must be maintained below 2900 degrees F, a temperature well below that at which rapid fuel deterioratica is anticipated.
These analyses also conservatively assume chat rapid onset of fuel failure occurs at approximately 3137 degrees F.
Experiments performed subsequent to these
- analyses, involving core heatup simulation tests on irradiated FSV fuel, have shown that the onset of failure is delayed until temperatures above 3400 degrees F are reached (Ref.10).
If it is arbitrarily assumed that the approximately 2.7% of the fuel that is predicted to exceed 2900 degrees F during this relatively short transient would suffer failure of the fuel particle coatings, this would be less than the 5% fuel failure allowable for normal operation and accounted for in
A.ttachment 4 to P-87002 Page-11 design and safety evaluations (FSAR Table 3.7-1).
Operations to date have indicated fuel failure fractions are at least an order of magnitude below. the approximately 5%
~
" Design" level of. failed fuel coatings.
Since the primary coolant pressure stays well below the PCRV' relief valve setpoint, and the PCRV liner and PCRV maintain their.. integrity, any fission products released from failed fuel would be retained within the primary coolant boundary.
Therefore, the offsite dose consequences for this postulated accident would not be significantly affected.
The above analysis bounds the consequences of a hypothetical accident _ occurring during past plant operating history which would. have required Safe Shutdown Cooling and utilized the EES sections.
In any case, recovery from a 1-1/2 hour interruption of forced cooling without exceeding 2900 degrees F
is considered part of the present licensing basis of the plant.
Discovery that fuel temperatures cannot be maintained beluw 2900 degrees F was considered to be a condition outside the present design basis and was cause for submittal of LER 86-026 (Ref. 4). The 2900 degree F limit is the basis for the reanalysis of Safe Shutdown Cooling at reduced power described in Section 111.1.4 following.
l
to P-87002 Page 12 III.
SAFETY ANALYSIS III.1 Description of Safe Shutdown Cooling with EES III.1.1 Safe Shutdown Cooling Following a HELB Accident
-Following a High Energy Line Break (HELB) accident in either the Reactor or Turbine Building, there is the possibility of a harsh environment in the building affected by the break, which could place restrictions on personnel access.
Figure. III-1 shows that the Emergency Condensate Header and the Emergency Feedwater Header are the redundant flow paths
'used to supply cooling to the EES. Both are seismically and environmentally qualified. The Emergency Condensate Header is the preferred path in the event of a HELB, to avoid exposure to a harsh environment in the Reactor or Turbine Building.
The two new valves HV-4518 and HV-4519 shown in Figure III-1 will be operable from outside the harsh environment to supply the Emergency Condensate Header with firewater. A modification to in: tall this capability is being completed under Change Notice CN-2270 during the current EQ outage.
(It is important to note that this same flow path is seismically qualified and would be suitable following a Design Basis Earthquake or Maximum. Tornado).
Another modification will provide seismically qualified six-inch vent lines to atmosphere from each EES discharge header (see Fig.
III-1).
These.new vents assure independence'of the redundant EES heat exchanger Safe Shutdown Cooling discharge path:.
They also reduce flow resistance downstream from each EES when required for the once-through mode used for Safe Shutdown Cooling, resulting in a higher firewater flow rate and greater heat removal capability.
This modification will be installed prior to exceeding 39%
-power.
Upon NRC approval of PSC's proposed Phase 2 Inservice Inspection and Testing Program Technical Specification changes (Ref. 20), the manual valves in the Safe Shutdown Cooling flow paths will be functionally tested at a
surveillance interval not to exceed 18 months.
This sorveillance testing will encompass the isolation valves in the new 6 inch vent lines.
Although part of this preferred Safe Shutdown Cooling path consists of a single line (the Emergency Condensate Header),
the system does meet the single active failure criterion (Refs. 11, 12, and 13).
Any single active failure to function of an electrical component of the two valves (HV-4518 and HV-4519) in the line can be compensated for quickly by a manual action in a mild environment.
ma
I i
)
to P-87002 Page 13-For certain HELB break locations in the Turbine Building, in conjunction with a specific single active failure, manual actions by an o in.a harsh environment could be required.(Ref. 11)peratorThese actions would be to manually open the valve which, although environmentally qualified, did not open due to the~. arbitrarily assumed -coincident single failure of its actuator to function. Table III-1 lists the break locations, the corresponding single active failures, and the manual actions required.
The valves are shown schematically on Figure III-1. There is only one manual action that may be required to be performed by the operator in the harsh environment, that is, opening the Emergency Condensate isolation valve (HV-2237 or HV-2238)'or feedwater inlet valve (FV-2205 or FV-2206). These valves are easily accessible and would be in the harsh environment only for a HELB inside the Turbine Building. Local manual operation of one of these valves would be required only if the' valve actuator were the single active failure. However, as these actuators are seismically and environmentally qualified, there is only a low probability that one of these valves would not function by remote operation from the Control Room after the HELB event. The approximate time in which this action would be required would be one hour following' break detection or interruption of forced circulation.
The composite EQ Program temperature profile shows that temperatures would have abated sufficiently within one hour such that access with " cool _ suits" would be possible (Ref.
14).
(The one-hour temperature is also considered tolerable to perform brief manual actions, such as described above, without " cool suits.") There is time enough to accomplish any necessary manual actions (as listed in Table III-1) and
. restart forced circulation cooling within the 1-1/2 hour.
delay assumed for the Safe Shutdown Cooling analysis (Ref.
17).
All other required manual actions identified in Reference 11
-do not require access to the harsh environment, including the access routes from the Control Room to the action locations.
A recent search for single failures involving the on-site essential electrical system, in conjunction with an HELB, has determined one combination of events of concern.
This concern will be remedied prior to exceeding 39% power.
The combination of events is: (1) the HELB causes loss of the use of the EES in one loop, and (2) the electrical single failure obviates use of either 480 Volt Essential Bus No.1 or No. 3.
With this combination of events, electrical power to two of the three circulator bearing water pumps serving the operating helium loop could be lost, when two-out-of-three of these pumps are required to be operating. The solution being developed to address this particular single failure event in combination with an HELB would involve
to P-87002 Page 14 installation of a temporary configuration in which the helium circulator bearing water pumps normally powered from 480 Volt Essential Bus No. 1 or No. 3 would be powered from 480 Volt Essential Bus No. 2, depending on which essential bus is incapacitated by the single failure.
This will be described in detail in a new procedure to be completed prior to exceeding 39% power.
It is tentatively estimated that the required manual actions can be accomplished in.less than one-half hour following the postulated electrical failure.
No entrance into the HELB harsh environment will be required.
III.1.2 Safe Shutdown Cooling Following a Seismic or Maximum Tornado Event Following a Design Basis Earthquake or Maximum Tornado event, Safe Shutdown Cooling with firewater can be achieved by manually operating the necessary valves, as discussed in FSAR Section 10.3.9 (with revised supply and discharge paths as describec' in this report). The redundant flow paths to the two EES sections are schematically shown in Figure II-1.
(Note that the reheater path line shown in dashed lines in Figure 11-1 will not be relied upon for Safe Shutdown Cooling in the future after authorization for operation above 39% power is received.) Safe Shutdown Cooling with firewater using either of the two EES sections for heat transfer meets the single failure criterion.
111.1.3 Safe Shutdown Cooling With Single Failures in Cooling Water Supplies FSAR Section 10.3.10 discusses " Safe Shutdown Cooling with Single Failures in Cooling Water Supplies." There the Safe Shutdown Cooling mode (discussed in FSAR Section 10.3.9) is shown to have the capability to withstand an arbitrary single failure in any of the cooling water supplies.
(This is true even without reliance on the reheater.)
This postulated single failure could be associated with a pump, a valve, or a pipe. The two primary coolant heat removal loops have an EES section in each loop (plus a reheater section, which will not be relied upon in the future for Safe Shutdown Cooling).
Each EES section is capable of being supplied cooling water from either the Emergency Condensate Header or the Emergency Feedwater Header, both of which are seismically qualified and tornado protected.
Heat removal by one of the EES heat exchangers is adequate for Safe Shutdown Cooling following a 1-1/2 hour 10FC from power levels up to and including 87.5%, using firewater supplied by a single fire pump (Ref. 5).
Certain Safe Shutdown Cooling valves (in the firewater and emergency booster pump lines) have recently been identified as single failure points, assuming passive failure of the
1
- to P-87002 Page 15 valve's. pressure' boundary function (Ref.
16).
The corrective action required the addition of redundant manual isolation valves to. provide-the single passive failure compliance.
These corrections are being carried out during the current outage under Change Notices CN-2424 and CN-2270, thus assuring single passive failure (as well as single active failure) criterion compliance.
A single passive failure (e.g.,
involving the Emergency Condensate Header, which is the preferred Safe Shutdown path) need not be assumed prior to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> following the initiating accident, per Reference 15.
If the Emergency Condensate Header suffers a passive failure after 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, personnel can manually initiate operation of the Emergency Feedwater Header expeditiously.
The Emergency Feedwater Header thereby serves as a redundant flow path to the Emergency Condensate Header.
Both are seismically and environmentally qualified flow paths, and ' protected from
. tornado damage.
A summary of the redundant means for providing forced circulation cooling of the core is given in Table III-2. As can be seen, either of the two loops can be used to cool the core and either of two circulators can be used in each loop.
In addition (and taking no credit for reheaters), there are five sources of cooling water to the -EES section of each steam generator and five sources of motive power to either of the circulators. While not all of the cooling modes have equal heat removal capacity (as shown in the FSAR, Section 14.4), and not all modes are seismically qualified, all of the EES modes.are capable of safely cooling the core from the reactor power operating level limit that will be proposed to the NRC in a separate submittal.
In addition to the redundant forced circulation cooling modes, and in the highly unlikely event of their complete
- failure, the core may also be cooled safely, solely by operation of one of the two loops of the PCRV liner cooling system as described in the FSAR, Sections 9.7 and 14.10.
This may be accomplished using only seismically qualified and tornado protected equipment. The analysis of this mode of cooling is described in Appendix D to the FSAR.
The offsite doses from this complete loss of forced circulation cooling accident (DBA No.1), as shown in FSAR Table 14.13-1, are many orders of magnitude below 10CFR100 guidelines.
III.1.4 Transient Analysis of Safe Shutdown Cooling With EES from 87.5% Power At the request of PSC, GA Technologies Inc., in conjunction l
with Proto-Power Corporation, have performed evaluations of Safe Shutdown Cooling as described in updated FSAR Sections 10.3.9, 10.3.10, and 14.4.2.2.
In work summarized in t
y
to P-87002 Page 16 Reference 4,
it was pointed out that steaming as predicted in the FSAR in the main bundle (EES) of the steam generator may. degrade secondary coolant flow rate to the degree that Safe Shutdown Cooling could be compromised.- The analysis in the FSAR was' based upon 1000 gpm firewater flow to the' EES modules of one loop and slightly less than 3% helium flow provided by boosted firewater to one circulator Pelton-wheel drive.
The purpose of the study summarized herein (described in Ref. 5) was to evaluate the maximum power level at which-Safe Shutdown Cooling can be performed using EES cooldown without exceeding the maximum fuel temperature of 2900 degrees F and without boiling in the secondary side of the steam generator. Safe Shutdown Cooling transients on a single loop (6 modules), following a 1-1/2 hour interruption of. forced cooling, were studied to evaluate firewater cooling capability with the new six-inch' vents shown in Figure III-1. Previous analyses were based on the piping resistance' downstream from the steam generator prior to installation of the new six-inch vents.
It did not take advantage of the new vent lines to atmosphere from the discharge of each EES as shown in Figure III-1.
These seismically-qualified vents (to be installed prior to exceeding 39% power) will have a lower resistance to flow when used for Safe Shutdown Cooling. The analysis described in this section does consider this lower resistance flow path.
Two major cases were studied: one case with cooldown using equipment satisfying Environmental Qualification (EQ) requirements, the EQ case; a second using equipment satisfying 10CFR50 Appendix R reovirements, the Appendix R case.
The EQ case involves the firewf.ter system in an open loop arrangement for supplying water to the steam generator and Pelton wheels.
The limiting Appendix R case involves water supply from the condensate system operating open loop for 5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> followed by closed loop operation. Because the condensate pumps are not on the Safe Shutdown List, the Appendix R case is not discussed further in this safety analysis.
Conditions for the EQ case included 940 gpm of 80 degrees F firewater flow to the Economizer-Evaporator-Superheater (EES) sections of six steam generator modules in one loop with helium flow adjusted to maintain 255 degrees F steam generator water exit temperature at 76 psia indicated pressure. The liner coo. ling system was assumed to be unavailable.
The results from the transient analyses showed a cooldown can be obtained from 85% rated feedwater flow (87.5% reactor power) using EQ qualified Safe Shutdown equipment. The s
n--
' Attachment 4 to P-87002 Page 17-helium flow' required to_ maintain subcooled water ccnditions at the EES exit varied between a minimum of 1.4% (14.6.lb/s) and a maximum of 3.8% '(37 1b/s).
This is within-'the operating range of a single circulator on its Pelton wheel drive. _The peak fuel temperature, as predicted by.the RECA code, was 2858 degrees F for the EQ case (Figure III-2).
This is below the FSAR 2900 degrees ~ F= limit.
Primary-coolant pressure (Figure III-3) stayed below the setpoints of the prestressed concrete-reactor vessel (PCRV) rupture =
discs and relief valves. The temperatures of the reheater and EES sections of the steam generator (Figure III-4) and the circulators were maintained within allowable operating limits throughout the cooldown transient (Refs.
5, 18.and 19).
The boiling margin in the hot module was 12 degrees F below boiling.
Based ~on: the above results, it was concluded that an acceptable EES cooldown can be obtained from 87.5% power C
using firewater and EQ qualified Safe Shutdown equipment.
III.2-Cy_:parison of the EES Cooldown with Regulatory Requirements.
III.2.1 Comr:arison with PWR Auxiliary Feedwater System.
The NRC regulations, regulatory guides and standard review plans are written' based on light water reactor (LWR) designs.
The closest counterpart to FSV's use of Safe Shutdown Cooling with firewater for the LWRs is the. use of the Auxiliary Feedwater System- (AFS)' in the pressurized water reactor (PWR). The reascns for this conclusion are that the PWR AFS and the FSV Safe Shutdown Cooling system have-the following common characteristics:
1)
Both involve safe shutdown with the pressure vessel and associated piping intact.
2)
Both use an intact steam generator and associated secondary cooling system piping (no LOCA is assumed).
3)
Both use a pumping source which is not utilized during normal full power operation.
4)
Both are the prime means of Safe Shutdown Cooling following a seismic event.
NOTE:
Each PWR steam generator has only one heat exchanger section and is thus comparable with the use of only the EES section of the FSV steam generator.
In view of the above, the deletion of the reheater cooling option and use of the redundant EES sections for FSV Safe Shutdown Cooling was reviewed against the NRC guidelines for
to P-87002 Page 18 the PWR AFS as contained in the PWR Standard Review Plan (SRP), Section 10.4.9 (Ref.
12), Subsection III.2. The comparison is shown in Table III-3 of this report.
The review criteria of SRP 10.4.9 are used as a basis for determining compliance with the applicable General Design Criteria identified in Subsection III.2.2 of this report.
The conclusion is that the deletion of the reheater Safe Shutdown Cooling option and use of only the EES Section for Safe Shutdown Cooling with firewater does not reduce the compliance of FSV Safe Shutdown Cooling with NRC requirements.
III.2.2 Comparison of EES Cooldown with General Design Criteria The effects of deletion of the use of a reheater for Safe Shutdown Cooling and total reliance on the use of a EES section for Safe Shutdown Cooling was compared with the bases for compliance with the General Design Criteria as contained in the FSV FSAR Appendix C.
A statement that the reheaters will not be relied upon as a viable option for Safe Shutdown Cooling will be noted in the appropriate GDC discussions in FSAR Appendix C (the reheaters continue to be capable of providing cooling for other abnormal events).
The criteria affected by this change were determined to be as discussed below.
It is concluded that the intent of these criteria continue to be satisfied by the design of the plant without reliance on a reheater for Safe Shutdown Cooling.
Criterion 38: Reliability and Testability of Engineered Safety Features In the discussion concerning this criterion, reference is made to the use of the reheater as an option for decay heat removal.
A clarifying note will be added to state that the reheaters are not relied upon for the strictly defined Safe Shutdown Cooling (i.e.,
using only one firewater pump and other Safe Shutdown list equipment following a 1-1/2 hour 10FC).
However, the reheaters continue to be capable of providing cooling for other abnormal events. This minor change will not affect compliance of FSV with the intent of this design criteria since the discussion on the reliability and testability of the EES section remains the same.
Criterion 41:
Engineered Safety Features Performance Capability This criterion requires that "As a minimum, each engineered safety feature shall provide the required safety function assuming a failure of a single active component." The discussion in Section 111.1.3 of this report addresses how the design will continue to meet the single active failure requirement without reliance upon the reheater sections of the steam generators.
t
to P-87002 Page 19 In the FSAR discussion concerning FSV's compliance with this criterion, it is noted that the steam generators contain both an EES section and a reheater section.
Further discussion is related to the ability of the EES section of either steam generator to remove decay heat ~following a scram from full power. No reference is made to the reheater's ability to remove decay heat. The resolution is again to add a note to clarify that the reheaters are not relied upon for Safe Shutdown Cooling.. However, the reheaters continue to be capable of providing cooling for other abnormal events. Thfs change will not affect FSV compliance with the intent of this design criterion.
Criterion 42:
Engineered Safety Features Components Capability This criterion requires that
" Engineered Safety Features shall be designed so that the capability of each component and system to perform its required function is not impaired by the effects of a loss of coolant accident." As stated in the FSAR discussion of this criterion, the analysis described in FSAR Section 14.11 shows that
'both the EES and the reheater bundle sections can survive the hypothetical Design Basis Depressurization Accident (DBA-2) without impairment of their performance capabilities, and therefore there would be no loss of emergency cooling capability as a result of a DBA-2.
Although the reheaters (as well as the EES) are mentioned in the FSAR discussion of Criterion 42, the safety analysis summarized in FSAR Section 14.11.2.2 and FSAR Figures 14.11-11, 14.11-12, and 14.11-13 is based upon use of one EES section for cooldown following DBA-2, with no reliance on reheaters (per FSAR Section 14.4.4). Therefore, deletion of reliance upon the reheaters for Safe Shutdown Cooling has no effect upon compliance with the intent of Criterion 42.
Criterion 43: Accident Aggravation Protection This criterion requires that Engineered Safety Features be designed so that any action of the Engineered Safety Features which might accentuate the adverse after-effects of the loss of normal cooling is avoided.
The deletion of reliance upon a reheater for Safe Shutdown Cooling (i.e., supplied by one firepump after a 1-1/2 hour interruption of forced circulation from full authorized power) does not change the existing discussion of this criterion.
The intent of Criterion 43 will continue to be met without relying on reheaters for Safe Shutdown Cooling.
Criterion 44:
Emergency Core Cooling System Capability This criterion requires that two emergency core cooling systems be provided.
In the FSAR discussion of this criterion either one of the normal coolant circulation loops is described as providing abundant emergency core cooling. The additional (and unrequired) redundancy
r to P-87002 Page 20 of heat removal capability within each steam generator is briefly mentioned (i.e., the EES section and the reheater section).
A clarifying note will be added to state that the reheaters are not relied upon for " Safe Shutdown Cooling," and that even without taking credit for the reheaters, the intent of this criterion continues to be met. However, the reheaters continue to be capable of providing cooling for other abnormal events.
Criterion 46: Testing of Emergency Core Cooling Systems This Criterion requires that design provisions be made to periodically test the active components of the emergency cooling system for operability and functional performance.
In the FSAR discussion of this criterion, either or both of the steam generator sections (EES sections or reheater sections) are identified to be capable of accomplishing emergency core cooling.
It is further stated that the system is composed of available equipment in a compliment of the two separate steam generator sections in each of the two loops.
As in Criteria 38, 41, and 44, a note will be added to clarify that the reheaters are not relied upon for Safe Shutdown Cooling.
However, the reheaters continue to be capable of providing cooling for other abnormal events. This note will not affect FSV compliance with this design criterion.
Other General Design Criteria All of the other discussions on the General Design Criteria remain unchanged as a result of the deletion of the reheater option from Safe Shutdown Cooling.
.g to P-87002 Page 21 IV. REFERENCES 1.
PSC letter P-86513, J.
W. Gahm to Document Control Desk, USNRC,
Subject:
Licensee Event Report 86-020, Preliminary Report, August 11, 1986.
2.
GA Technologies Inc. Document No. 909113B,
Title:
Firewater Cooldown Using One Reheater Module (1-1/2 Hour Delay),
R.C.
Potter, December 22, 1986, submitted to the NRC (Berkow) as attachment to PSC letter (from Warembourg) P-86682, December 30, 1986.
3.
GA Technologies Inc. Document No. 909052 N/C, title:
Firewater Cooldown with 300 degrees F EES Exit Temperature (1-1/2 Hour Delay), October 6, 1986.
4.
PSC letter P-86587, J.
W. Gahm to Document Control Desk, USNRC,
Subject:
Licensee Event Report,86-026, Final Report, October 17, 1986.
5.
GA Technologies Inc. Document No. 909269 N/C, title:
EES Cooldown for EQ and Appendix R Events With Vent Lines (1.5 Hour Delay), December 23, 1986, submitted to the NRC (Berkow) as attachment to PSC letter (from Warembourg)
P-86683, December 30, 1986.
6.
PSC letter, R. F. Walker, to A. Giambusso, dated January 9, 1975. Docket 50-267.
(This is a Pre P-letter, but is now assigned number P-75052).
7.
NRC letter, R. A. Clark to R. F. Walker, dated May 30, 1975.
Docket 50-267.
8.
PSC letter, R.
F.
Walker to R. A. Clark, dated June 23, 1975. Docket 50-267.
9.
PSC letter P-78178, J. K. Fuller to W. P. Gammill,
Subject:
Fort St. Vrain Accident Reanalysis, Request for Additional Information,
- October, 1978.
Response to NRC Question 222.010.
10.
PSC Letter P-79157, F.E. Swart to Themis P. Speis, USNRC, Subject, Fort St. Vrain Fuel Particle Coating Failure, July 24, 1979.
Subject:
Role of Operators in Mitigating High Energy Line Breaks at Fort St. Vrain, June 26, 1986.
- 12. NUREG-0800, Standard Review Plan for the Review of Safety Analysis Reports for Nuclear Power Plants, USNRC, July 1981.
Section 10.4.9, Auxiliary Feedwater System (PWR).
i to P-87002 Page 22
- 13. Supplement No.
1, Safety Evaluation by the Directorate of Licensing, U.S. Atomic Energy Commission, in the Matter of Public Service Company of Colorado, fort St. Vrain Nuclear Generating Station, Docket No. 50-267.
Issued:
June 12, 1973. Section 2.1 " Criteria."
- 14. PSC letter P-86208, R.
F. Walker to H. N. Berkow, USNRC,
Subject:
Fort St. Vrain Equipment Qualification, March 14, 1986.
- 15. SECY-77-439, E.
G.
Case to The Commissioners,
Subject:
Single Failure Criterion, August 11, 1977. Section 2.D.
(G-77146)
- 16. PSC letter P-86515, J.W.
Gahm to Document Control Desk, USNRC,
Subject:
Licensee Event Report 86-021, Final Report August 13, 1986.
- 17. PSC report EE-EQ-0026, Engineering Evaluation of the Procedure to Recover from an Actuation of the Steam Line Rupture Detection / Isolation System, for Power Levels Through X1, Draft December 10, 1986.
- 18. GA Technologies Inc. Document No. 909204 N/C, title: Effect of Firewater Cooldown Using EES Bundle on Steam Generator Structural Integrity, December 4, 1986, submitted to the NRC (Berkow) as attachment to PSC letter (from Warembourg) P-86682, December 30, 1986.
- 19. GA Technologies Inc. Document No. 908861 N/C,
Title:
FSV Calculations for Circulator Temperature-Related Operating
- Limits, November 13, 1986, submitted to the NRC as attachment to PSC letter P-86682, December 30, 1986.
- 20. PSC letter P-86498, R.
F. Walker to H. N. Berkow, USNRC,
Subject:
Proposed Tech.
Spec.
Changes Inservice Inspection and Testing Requirements, September 4,1986.
-Attachment 4
.to P-87002
.Page^23
' ~
' TABLE III-1 SINGLE ACTIVE FAILURES ASSUMED COINCIDENT WITH-HELB THAT REQUIRE MANUAL-ACTION WITHIN
~
TURBINE BUILDING s
' Break Location Single Active Failure Manual Action Feedwater or Main
.HV-2237 Notes 1, 3 Steam Loop 1 or Piping FV-2205-Notes 2, 3 Feedwater or Main HV-2238 Notes 1, 3 Steam Loop.2 or Piping FV-2206 Notes 2, 3 Note 1: Local operator manual action would consist of turning a handwheel to manually override the valve.
Note.2: Local operator manual action would be required to admit hydraulic fluid to the valve actuator.
Note 3: Access with " cool suits" would be possible within the time required to perform this action at approximately one hour after HELB when building temperatures would be 134 degrees F or less (Ref.14). This temperature is also considered tolerable to perform brief manual actions, such as'these, without " cool suits."
e f
---v,,..
, ~, -. -.-- - - -
7-to P-87002 Page 24 Table III-2
SUMMARY
OF FORT;D CIRCULATION COOLING REDUNDANCIES **
Number of Cooling Loops 2
Number of Cooling Sections per Loop 2 (EES* & Reheater)
Sources of Water to EES* (each loop):
1.
Normal Feedwater 3 Feedwater pumps:
(2 steam-driven, 1 electric motor driven) 2.
Feedwater via Emerg. Feedwater Line 3 Feedwater pumps 3.
Condensate via Emerg. Condensate Line 4 Cond. pumps
- 4.
Firewater via Emerg. Feedwater Line 2 Fire pumps:
(1 engine-driven, 1 electric motor-driven)
- 5.
Firewater via Emerg. Condensate Line 2 Fire pumps Scurces of Water to Reheater (each loop):
1.
Condensate via Emerg. Condensate Line 4 Cond. pumps 2.
Firewater via Emerg. Condensate Line 2 Fire pumps Number of Circulators Per loop 2
Sources of Motive Power to Circulators (each circulator):
1.
Steam HP Turbine Exhaust Steam, Flash Tank Steam, 2 Auxiliary Steam Boilers 2.
Feedwater via Emerg. Feedwater Line 3 Feedwater pumps 3.
Condensate via Emerg. Condensate Line 4 Cond. pumps
- 4.
Firewater via Emerg. Feedwater Line 2 Fire pumps
- 5.
Firewater via Emerg. Condensate Line 2 Fire pumps
- Indicates only future flow paths for Safe Shutdown Cooling
- Adapted from Updated FSAR Revision 3, Table I.2-2.
~
to P-87002 Page 25 TABLE III-3 EFFECT ON NRC REQUIREMENTS OF THE DELETION OF REHEATERS FROM FSV SAFE SHUTDOWN COOLING.
Stand.
Review Plan Section 10.4.9, Para.
NRC REQUIREMENT EFFECT OF REHEATER DELETION III.2.a.
Seismic Design Unaffected by the change since both EES sections are fully seismically qualified as are the redundant supply lines from the. firewater pumps to the EES sections.
III.2.b.
Other Natural Unaffected by the change since the i
Phenomena Reactor Building is designed to protect the steam generators and associated secondary coolant piping from the effects of a " Maximum" tornado. Also, equipment and piping in the Turbine Building below the turbine pedestal floor is similarly protected.
III.2.c.
Protection from the Elimination of reliance on reheaters Effects of High for Safe Shutdown Cooling does not Energy Line Breaks change cooldown capability assessed previously in FSAR Appendix I.
Shutdown using the EES section following an HELB is discussed in Section III.1 III.2.d.
Loss of Offsite Power This accident analysis (in FSAR Section 10.3.1) is unaffected by deletion of reheaters from Safe Shutdown Cooling.
III.2.e.
Single Active Failure Although the minimum number of LC0 4.3.1 required shutdown cooling heat exchangers is reduced from three to two, the single failure criterion will still be met by use of the EES sections only.
. Attachment 4 to-P-87002
-Page 26-Table III continued-III'.2.f.
Diversity in Pump-Unaffected by-the change since Motive Power' either the motor-driven or the engine-driven firewater pump can supply the EES sections.
III.2.g.- Instrumentation to'
.NA to FSV for " Safe Shutdown Automatically Cooling".
Unaffected by reheater Initiate Flow deletion since flow to EES.is restarted manually after 60 to 75 minute. delay, as was the case for the reheater.
III.2.h. Sufficient Flow Unaffected by reheater deletion since Capacity Safe Shutdown Cooling does not use flow to reheater and EES simultaneously.
EES has greater cooling capacity than reheater with same flow rate. The EES has adequate flow capacity when one firewater pump is supplying an EES and is providing motive power to drive a helium circulator.
j j
l[j, i~
y Adapted frcrn UPDATED FSAR Revision 2 Figure 10. 3 -4
]
NOTEI r- - - - '
I I
STORAGE PONOS l REHEATER I P
P I SECTION I TO I
I ATM CIRCULATING TO REACTOR BLDG. SUMP L_f_3 JI---
k I WATER MAKEUP k
OR NON-CLASS l PUMPS AND PIT I
J LINES VIA r- "
TURBINE-WATER I
NOTE 2
[3 y
[1 r DRAIN TANK I
jg i
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~
~
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SUPERHEATER l
SECTION f
[
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=
7 SUPPLY I
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l CIRCULATOR I
h co 1
1 r 1 r I
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I PCRV PUMP PUMP ORIVEj l
' BOUNDARY PIT PIT I
I l**
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~-
~
l ORIVEN l
l I
I FIRE PUMPS l-C Q
l EMERGENCY WATER
[
MOTOR BOOSTER l
DRIVEN PUMr$
g C
I j gl EMERGENCY l
CONDENSATE
[
LINE EMERGENCY FEE 0 WATER LINE Figure II-l Schematic Flow Diogrom: Cooling with Sofe Shutdown Eaulpment NOTE 1: Reheater will not be relied upon for Sofe Shutdown Cooling.
NOTE 2: Only one of two EES sections shown
h I
Fire Water Pumps j
V 45201 p'
One possible Emerg. Feedwater i
Hdr. pa t h
\\\\
\\
Turbine Bldg.
One possible Cmerg. Cond.
l Ring fleader
!!dr. path l
P-4501 j
HV-4520 q
!!V-4518 P-45n15 HV-4514 tiote:
This is a simplified diagram only showing the main lir.es l
To Ci nulators HV-31122 and valves. Valves are shown V-4525 i
C-2101, C-2102 "9
I E her. water sooste rmer. Condensate Header position.
um s Removable y ywwmmwvgh 109
.4%%%\\%\\M M
To Atm.
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~
li"'
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{
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gy, y.
)
HV-2201 223
)
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=W amm Normal CL.II CL.T
~
Sup ply-*-
f HV-223R llV-2204 HV-2202 FV-22 l
y New 6" Vent CL.II CL.I P-2209 Line l
1 figure III-I Safe Shutdown Flow Paths ilsing the EES Section I
1
)
Ansteettete laettets 18448833 864 $7(An FLOW. Etd C0048MS. 80 See GM alt F MAXIMUM FUEL TEMPERATURE 3064 TMAX
- as..
G R
E E
~
S 2006 1540-0 2
4 6
8 10 TIME, HOURS FIGURE III-2.
flaximum Fuel Temperature During Safe Shutdown Cooling lif th Firewater From 87.5% Power Using EES 9
.,.._m,,
I Aupt?9480 18/l$eN leseessa see stEdus Flow. (88 toottsas, te see Gme ass F PRIMARY SYSTEM PRESSURE 769 s )
666 d
P S
500 I
A 466 N
g o
a 360 n
9 4
6 16 TINE, hours I
l l
l l
Figure III-3. Primary System Pressure During Safe Shutdown Cooling With Firewater From 87.5% Power Using EES I
l i
i
EQ 949 GPM AT 255'F WATER 29H Legend Het Med.t.
y a, Me.....t.
- 1,g, C
(
r
.a t
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" 1999 r
e D
~
e
'. \\
see
. g.....
i 9
9 2
4 g
9 19 12 Time, Hours Figure III-4. Steam Generator Hot Module and Average Module Inlet Helium Temperature During Safe Shutdown Cooling With Firewater From 87.5% Power Using EES
.. _ _