ML19341A419
| ML19341A419 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 01/19/1981 |
| From: | Crouse R TOLEDO EDISON CO. |
| To: | Eisenhut D Office of Nuclear Reactor Regulation |
| References | |
| 679, NUDOCS 8101230485 | |
| Download: ML19341A419 (16) | |
Text
.
Docket No. 50-346 totsoo EDISON License No. NPF-3 Serial No. 679 AicsAao P. CROUSE va n,et January 19, 1981 N"*"
l4191259-5221 Director of Nuclear Reactor Regulation Attention: Darrell G. Eisenhut, Director Division of Licensing United States Nuclear Regulatory Commission Washington, D.C.
20555
Dear Mr. Eisenhut:
On January 5, 1981, Toledo Edison submitted (letter Serial No. 675) a package to support de-automation of Incident Level 5 of the Safety Features Actuation System (SFAS) at the Davis-Besse Nuclear Power Station, Unit 1, (DB-1).
Also on that day, members of my staff met with you and ysur staff in Bethesda, Maryland, to discuss this proposal for manual action to trovide appropriate long-term post loss-of-coolant accident (LOCA) core cooling.
Several discussions transpired concerning that submittal between your staff and Toledo Edison. As a result of those discussions, Toledo Edison submitted (letter Serial No. 678) another package on January 15, 1981. The details of this package were reviewed by your staff. That review also raised questions and discussions were held to resolve them.
This submittal is Toledo Edison's response to those questions. Attachment A lists the specific question and Toledo Edison's response.
Sincerely, ff
_= =
RPC:TJM:aa cc: DB NRC Resident Inspector
\\k THE TOLEDO EDISON COMPANY EDISON PLAZA 300 MADISON AVENUE TOLEDO, OHIO 43652 8101230 gff.f}
Dockst No. 50-346 License No. NPF-3 Serial No. 679 January 19, 1981 ATTACEMENT A 4
1.
The alarm showing Borated Water Storage Tank (BWST) low low level should annunciate when the permissive for the manual changeover is received, (i.e., a low low level as sensed by two out of the four BWST level transmitters).
RESPONSE
This feature'is provided by the changes.
2.
Does the interlock between the BWST outlet valves and the emergency sump isolation valves meet the separation criteria for safety grade equipment?
RESPONSE
Yes.
This modification was evaluate 4 as all safety grade electrical modifications at the Davis-Besse Station,by an Engineering Inspection Team when the feature was installed. This is in complete agreement with our Quality Assurance Program.
3.
Include testing of the interlock in the Technical Specifications.
RESPONSE
The simultaneous valve operation is an integral part of the functional test at 18-month intervals.
4.
If a spurious SFAS Incident Level 5 actuation occurs simultaneously with an actual SFAS Incident Level 2 actuation, will the SFAS Incident Level 2 actuations not occur due to the fact that Level 5 blocks Level 2?
RESPONSE
No.
A simultaneous occurance of a spurious SFAS Incident Level 5 and an actual SEAS Incident Level 2 will not affect the proper actuation-of the Emergency Core coding Systems (ECCS).
Incident Level 5 in the pro-posed modification causes no valve motion.
For the trains to be
" operable" in-service, they are properly aligned for Incident Level 2 actuation (DH7A&7B open and DH9A&9B closed). Therefore, a set of failures that provide a simultaneous or premature Incident Level 5 will result in no improper actions upon an Incident Level 2 demand.
Docket No. 50-346 License No. NPF-3 Serial No. 679 January 19, 1981 ATTACHMENT A (Cont'd) 5.
Procedure change concerns have been discussed by representatives of the Human Factors Branch of the NRC and Toledo Edison. The latest pro-posed changes are shown in Attachment B.
6.
Attachment C explains the electrical aspects of the proposed change, describing how the circuit will function after the change.
N f
)
l
ATTACHMENT B AP 3005.56.2 1
BWST LOLO LVL, XFER TO EMER SUMP 1.
SYMPTOM 1.1 This alarm is generated when any two of the four SEAS BWST level bistables trips.
1.2 Setpoint
8 feet water 1.3 Source Designation: LSL 1525A, LSL 1525B, LSL 1525C, and LSL 1525D 2.
1MMEDIATE OPERATOR ACTION 2.1 Verify there is dh8 feet in the BWST per LI 1525A, B, C, and D.
3 2.2 Verify a LOCA condition exists.
2.3 With the BWST level less than or equal to 8 feet, transfer pump suction to the emergency sump by blocking SFAS incident level 2 for DH9A and DH9B and then opening DH9A and DH9B using HISDH9A and HISDH9B. Verify that the BWST outlet valves DH7A and DH7B start to close as DH9A and DH9B start to open. Verify the transfer is complete by checking the indicating lights on DH7A and B and DH9A and B and by checking that low pressure injection flow has not substantially changed.
3.
SUPPLEMENTARY ACTIONS 3.1 Refer to EP 1202.06, Loss of Reactor Coolant, Reactor Coolant Pressure.
4.
DISCUSSION This alarm is actuated when SFAS incident level 5 is tripped, which allows the the transfer of DH and CS pump suction to the emergency sump to be completed.
This alarm provides assurance to the operator that the transfer can be completed.
1 i
END
d ATTACEMENT B SP 1104.04.16 31 DH 831 (DH 830) when DH Pump 1-1 (1-2) line flow is higher. Then balance the flow to 1500 gpm per line by adjusting the flow control valves DH14A and DH14B.
If no air is available to DH14A and DH14B, the DH in-jection valve DH1B (DHIA) can be throttled under emer-gency conditions. This motor operated valve only moves while control switch is held.
9.2.3 Deleted 10.
RECIRCULATION FROM THE CONTAINMENT VESSEL EMERGENCY SUMP Following a LOCA, the BWST level will decrease until at the 8 feet level the operator must mannally transfer the suction of the DH and CS Pumps to the emer-gency sump. The operator will open the emergency sump outlet valves DH9A and DH9B and close the BWST outlet valves DH7A and B.
Note that SEAS incident level 5 must be actuated before the transfer can occur; this requires any two channels 16 of SFAS logic to reach the low level setpoint of 8 feet. The annunciator "BWST LOLO LVL, XFER TO EMER SUMP" will indicate that the incident level 5 logic has been actuated and that the transfer is possible. The annunciator does not meet safety grade specifications however and therefore must NOT be relied upon to in-dicate the incident level 5 trip. When the 8 feet level is reached (as indicated on LIl525A, B, C, and D), the annunciator should be received and the transfer should be initiated. Considering the worst case instrument tolerances, the SEAS incident level 5 actuation will occur by the time the indicated BWST level reaches 6 feet so the transfer should have been completed by that time.
No operator signoff is required for Section 10.
10.1 Prerequisites 10.1.1 Low pressure injection in progress.
10.1.2 Borated Water Storage Tank water level has reached the low level transfer setpoint (8 feet) as read on LI1525A, B, C, and D.
10.1.3 Deleted 10.2 When the BWST level reaches 8 feet, attempt to transfer the suction of the DH and CS Pumps to the emergency sump as described below. Continue-the 16 attempts until the transfer is complete. The annunciator "BWST LOLO LVL, XFER TO EMER SUMP" provides assurance to the operator that the transfer j
can be completed.
10.2.1 Block SFAS incident level 2 on DH9A and DH9B.
l 10.2.2 Open DB9A and DH9B using HISDH9A and HISDH9B.
l 16 10.2.3 Verify that DH7A and DH7B start to close as DH9A and DH9B start to open.
10.2.4 Verify that the transfer is complete by checking the indicating l
lights on DH9A and B and DH7A and B and by checking that the low pressure injection fle> was not significantly changed.
10.2.5 Continue low pressure injection as needed.
1 h
-a 33 SP 1104.04.15 NOTE:
The preceding three steps establish the
" piggyback" mode of operation.
If this i
operation is being formed to provide RCS makeup at high pressure, no further action is required until makeup is no longer needed at which time the pumps may be stopped and DH 63 and DH 64 closed.
If this operation is the result of an RCS leak and the BWST level is approaching g,
g jr
,6 feet, continue with the remaining steps.
b[
15 11.2.4 Close the high pressure injection pump minimum recirculation valves to the BWST. This is,to minimize the contamination of the BWST and maintain off site radiation levels as low as possible.
15 NOTE:
If, DH 64 (DH 63) and HP 32 (HP 31) are both open, computer alarm ~ Q488 (Q489) will occur.
15 CAUTION:
If the high pressure injection flowrate drops to fE35 GPM per pump due to an increase in RCS pressure, stop the high pressure injection pumps 1-1 and 1-2 so as not to damage them.
11.2.5
- SEE ATTACHED SHEET FOR STEP 11.2.5*
A 7
11.2.6 When Reactor Coolant Pressure is low enough for 15 l the Decay Heat Pumps to discharge directly to the Reactor Coolant System at a flow of 2000 gpm, begin Decay Heat System recirculation of the Containment Vessel Emergency Sump as follows:
15 11.2.6.1 Stop the High Pressure Injec-tion Pumps 1-1 and 1-2 if their flow is not needed.
11.2.6.2 Shut the Decay Heat Pump I
discharge valves to the High Pressure Injection Pump Suction Dh 63 and DH 64.
Section 11 Completed Date
i
\\
1 11.2.5 When the BWST level reaches eight feet, attempt to trans-fer pump suction to the emergency sump by blocking SFAS incident level 2 for DH9A and DH9B and then opening DH9A and DH9B using HISDH9A and HISDH9B. Verify that the BWST outlet valves DH7A and DH7B start to close as DH9A and DH9B start to open. Verify the transfer is complete by checking the indicating lights on DH7A and B and DH9A and B and by checking that low pressure injection flow has not substantially changed.
NOTE: SFAS incident level 5 must be tripped (at 8 feet BWST level) before the transfer will work.
The annunciator "BWST LOLO LVL, XFER TO EMER SUMP" provides the operator assurance that the transfer is possible, but since this alarm may NOT ba relied upon to work, continue to attempt the transfer until l
completed (see Section 10 for further explanation of this interlock).
t i
i 4
1
ATTACHMENT B EP 1202.06 24 5
The supplementary actions to be taken vary with the availability of equipment and other factors. To aid in determining the proper sequence of actions to take, a flow chart indicating the various paths the actions might take has been included as Figure 1.
Note that step numbers have been included on the figure to simplify correlation to the steps of corrective action.
Note that the actions listed describe general methods of dealing with the accident and specific instructions on the operation of equipment are omitted.
The time span over which these actions are performed is sufficient to consult other document,s and the operator should use other procedures, drawings, etc., to aid in completing these actions.
NOTE:
Check Emergency Plan Acti;ation, E! 1300.01 to determine if Emergency 14 Action Levels have been exceeded 2.4.1 Initial Actions For additional guidance on the following subjects, consult Section 2.6 before taking any actions relative to those subjects.
1.
Blocking of any safety equipment functions including EPI 2.
Switching of HPI suction to emergency sump if HPI still g
required when BWST low level (8 feet) reached.
jr 3.
Unusual or offscale indications develop 4.
Isolation of a leaking OTSG 5.
Anticipated loss of all RCPs 6.
See attached sheet 7.
See attached sheet 2.4.1.1 Attempt to locate and iso'lEte'the leak if possi61e. ~ " ' ~ ~
Isolable leaks include the electromatic relief valve (close the block valve), a break between the control valve and block valve on the spray line (close both valves), and a makeup system' leak (close letdown).
2.4.1.2 Start a plot of RCS pressure vs. hotleg (and/or incore thermocouple or vide range Tc if nothing else is avail-able) temperature on Figure 2 and a plot of temperature vs. time on Figure 3.
These plots will make it possible to track the plant's condition through plant cooldown.
Primary temperature and pressure will decrease along the saturation curve until subcooled conditions are established.
This will be indicated by primary system pressure no longer following the saturation curve, as primary system pressure should be controlled by adjusting 0
HPI flow, to maintain 50 F cooling.
High pressure injection may be stopped or throttled, provid ed the criteria of Section 2.6.1.6 are met.
NOTE: If the plant computer is not available for incore thermocouple readings, refer to 14 IC 2001.07, Manual Measurement of Incore Thermocouples.
2.4.1 Initial Actions 6.
Erroneous steam generator and pressurizer level indications due to unusual containment conditions.
7.
Transfer of DH and CS pump suction to the emergency sump on BWST low level (8 feet).
l i
f e
" ~ - - - - -
4 EP 1202.0614 6
METERS, the hot leg termperature -
4 If either the RCS TSAT indications, or the incore thermocouple temperatures indicate super-heated conditions for the existing pressure, refer to AB 1203.06, Inadequate Core Cooling o Guidelines.
An increase in the source or intermediate range nuclear instrumentation may also indicate an inadequate core cooling situation.
2.4.1.3 If both main and auxiliary feedwater is lost, refer to AB 1203.05, Complete Loss of Main and Auxiliary Feed-water, to aid in restoring auxiliary feedwater in the event both OTSGs are dry.
2.4.1.4 See attached sheet 2.4.1.5 Determine the availability of reactor coolant pumps (RCPs).
If any RCPs are running, go to 2.4.2.
If all
.RCPs are off, go to 2.4.3.
2.4.2 Actions with at least one RCP rhnning 2.4.2.1 Maintain one RCP running per loop (stop other pumps).
Continued operation of at least one RCP is desirable.
The only conditions requiring RCPs be stopped would be if RCS pressure falls below 1650 psig such that SFAS incident level 2 is actuated or if the KCP vibration as measured by the Bentley-Nevada equipment exceeds 30 mills. Note that the X2 (times-two) switch on the Bentley-Nevada equipment must be used for the expanded range.
2.4.2.2 Allow RCS pressure to stabilize.
If RCS pressure con-rinues to decrease past secondary side pressure, the leak is large and section 3 should be consult,ed.
2.4.2.3 Establish and maintain OTSG cooling by adjusting steam
. pressure via the turbine bypass valves and/or atmos-100 7'per hour to 0
pheric vent valves.
Cooldown at achieve an RCS pressure of 250 psig.
Track the cool-14 down on Figures 2 and 3.
Isolate core flood tanks s-0 when 50 F subcooling (using RCS T METERS) is SAT l
attained and RC pressure is less than 700 psig.
l
. plock SPAS 1,eveL*3, klyen less than.600 psig.
2.4.2.4 Go into LPI cooling described in 2.5.1 i
2.4.3 Actions with no RCPs running 1
2.4.3.1 Verify that the OTSG level is maintained at 96" on the startup range by auxiliary feedvater.
1 i
NOTE:
If desired, the OTSC level may be raised as high as 95% on the operate range to improve RCS cooling but the transition must be slow enough to prevent i
excessive changes in RCS pressure and temperature.
)
I
2.4.1.4 Begin monitoring BWST level on LI1525A, B, C, and D and manually trans-fer pump suction to the emergency sump when the BWST level reaches 8 feet. Transfer pump suction to the emergency sump by blocking SFAS incident level 2 for DH9A and DH9B and then opening DH9A and DH9B using HISDH9A and HISDH9B. Verify that the BWST outlet valves DH7A and DH7B start to close as DH9A and DH9B start to open. Verify the transfer is complete by. checking that the indicating lights oa DH7A and B and DH9A and B and by checking that low pressure injection flow has NOT substantially changed.
NOTE: SFAS incident level 5 must be tripped (at 8 feet BWST level) before the transfer will work. The annunciator "BWST LO LO LVL, XFER TO EMER SUMP" provides the operator assurance that the transfer is possible, but since this alarm may NOT be relied upon to work, continue to attempt the transfer until completed (see Section 2.6.7 for further explanation of this interlock).
i 1
l l
-w-
e-EP 1202.06.12 15 2.6.4 If high activity is detected in a steam generator, isolate the leaking generator.
If high activity is detected in both genera-tors, isolate only the one that appears to be leaking the most; l
do NOT isolate both steam generators.
If an OTSG is leaking, consult EP 1202.57, OTSG Tube Leak Emergency Procedure.
This procedure should be followed in conjunction with this procedure but if any conflicts between thh required actions should arise, the actions required in EP 1202.06 take precedence.
2.6.5 If, while performing the actions of this procedure a condition develops such that the loss of all RCPs is anticipated, go to EP 1202.14, " Loss of RC Flow - RC Pump Trip, for instructions ou a controlled transition to natural circulation.
2.6.6 If containment temperature is elevated, compensation is required for potentially erroneous SG and pressurizer level indication.
The elevated reference leg temperature causes the measured level to indicate higher than actual level. Therefore, if containment temperature is elevated above 1500F, (as read by TI1356, TIl357, TI1358, or CPT T298, T302, T306), manually control the indicated SG 1evel at greater than 60" if incident level 2 is NOT present or at greater than 125" if incident level 2 is present.
Maintain pressurizer leve? at greater than 00" as read by the compensated pressurizer level recorder LRS RCl4 if containment temperature 0
is above 150 F or manually shut off the pressurizer heaters if indicated level drops below 80" to prevent uncovering the heaters.
If RCS pressure drops below 600 psig within several minutes, off-gassing of the reference leg may interfere with pressurizer level indication. The operator should, if he can, shut off all pres-surizer heaters to prevent possible burnup. They may be re-energized when RCS pressure reaches approximately 1600 psig and pressurizer level increases to approximately 100 inches.
Also, note the'CF tank levels, SG operating range levels, and SC full range levels may be affected by the increased containment t emperature.
For further details, see the appropriate operating procedure:
SP 1104.01, CF System Operating Procedure SP 1103.05, Pressurizer Operation SP 1106.07, Main Feedwater System Operating Procedure 2.6.7 See attached sheet f
i
o j
2.6.7 Following a LOCA, the BWST level will decrease until at the 8 feet level the operator must manually transfer the auction of the DH and CS Pumps to the emer-gency sump. The operator will open the emergency sump outlet valves DH9A and DH95 and close the BWST outlet valves DH7A and B.
Note that SFAS incident level 5 must be actuated before the transfer can occur; this requires any two channels of SFAS logic to reach the low level setpoint of 8 feet.
The annunciator "BWST LOLO LVL, XFER TO EMER SUMP" will indicate that the incident level 5 logic has been actuated and that the transfer is possible.
The annunciator does not meet asfety grade specifications however and therefore must NOT be relied upon to in-dicate the incident level 5 trip. When the 8 feet level is reached (as indicated on LIl525A, B, C, and D), the annunciator should be received and the transfer should be initiated. Considering the worst case instrument tolerances, the SFAS incident level 5 actuation will occur by the time the indicated BWST level reaches 6 feet so the transfer should have been completed by that time.
l
~
EP 1202.06.13 16 2.7 Discussion For the purposes of this procedure, a medium sized leak is one for which the HPI pump capacity is sufficient to maintain pressurizer level or RCS
]
pressure.
If the HPI pumps cannot keep up with the leak, then RC pres-sure will fall entil the LPI system can provide additional makeup; this is defined as a large leak and is discussed in the next section.
Depending on the size of the leak, the RCS pressure will slowly or quickly fall to the 1600 psig pressure setpoint of the SFAS for level 1 add 2 actuation. Note that for small breaks with a complete loss of feedwater, L3 RCS pressure may not fall low enough to actuate SFAS levels 1 and 2.
Manual actuation of SFAS could be accomplished by actuating each component in level 1 or 2 or by actuating levels 1, 2, 3, and 4 except C.S. pumps, by means of the manual actuation pushbutton.
Manual 3
actuation will result in natural circulation of the RCS and an SFRCS w
.E T*3 actuation. Operator action shall be taken to re-establish the seal E T $ % 0' injection and CCW to the MU Pumps to allow continuous operation of the 8$*oO RCPs. Manual actuation should NOT be used unless the SFAS setpoints are
- $ $ m' reached and the actuation does not occur.
Once HPI is initiated and
-E$0Y#
level is restored to enable pressure control, a cooldown can be started.
- EeE$
The cooldown should proceed normally with the exception that one of the seo"8 ECCS pumps must remain in operation in the injection mode to makeup the 555SU water lost out of the leak. HPI can be shutdown within the limits of
- gu o}
item 6 of 2.6.1.
.E " w T 0 If possible the depressurization/cooldown will be complete before the
- ce u
- o. 0 $ U S BWST low level is reached and the "piggybacking" of the HPI and Decay hgh3u Heat Pumps will not be necessary.
If the depressurization/cooldown cannot g u:
be completed in time, the pressurizer level may be maintained by aligning a
g,yAg the Decay Heat Pusps to take P. suction from the emergency sump and discharge
- gouh, to the suction of the HPI pu:4,s.
E0*m32 gg3ggg A flow path from the RCS hot leg to the DH System must be established
, o a w g,g within seven days to prevent boron concentration buildup as described in 5ycoog Section 3.4.8.
If this flow path cannot be established, an alternate
, H,,, j 2 path through the auxiliary spray line must be used.
. E id " Y gy,x3g If an operator blocks an SFAS signal and changes the status of the actua-tgoj,t ted equipment, he is responsible for assuring proper qquipment operation ggg3gy and re-initiation if required until the SFAS is reset.
For guidance on u y 8, a 8 'g resetting the. SFAS after a real or erroneous trip, see Section 4.0.
ky,'Eu
%o5 3gd For additional details on possible consequences of a medium sized leak, see The Evaluation of Transient. Behavior and Small Reactor Coolant
,yc g,s otgy3J j System Breaks in the 177 Fuel Assembly Plant - Section 5 (B&W).
U E. " :" o q, g, g,,,
Notes on Step 2.4.3.5 l
E*30o0
$gg8 When this step is reached, auxiliary feedwater has established a 96" level am
,d;*gS in the OTSGs and no RCS flow exists (forced or natural). Depending on the g,cggm size of the break, the RCS may repressurize enough to reach the code safety valves s.etpoint.
If the electromatic relief is available, the RCS pressure may be reduced manually.
If not, the RCS pressure will be relieved by the break and the safeties if the pressure goes that high. At some pressure, the enargy escaping from the break (and the electromatic or safeties if used)
EP 1202.0& l4 18 3.4 Supplementary Actions 14 Implement Site Emergency Procedure, EI 1300,04, CAUTION:
DO NOT BLOCK AND OVERRIDE ANY SAFEIY EQUIPMENT EXCEPT AS SPECI-FIED IN SECTION 2.4.3.
3.4.1 If the flow rate between the two HPI lines for an HPI Pump becomes unbalanced, throttle the HPI valves and split the flow between the injection lines.
Do NOT throttle the line with the high flow below the flow rate shown on Figure 4.0.
Assure proper HPI operation per Section 5.0 of SP 1104.07, "HPI Operating Procedure".
'**==.
When LPI is actuated and LPI flow is greater than 1000 gpm per pump for 20 minutes, the operator may stop the HPI pump.
3.4.2 Verify the LPI pumps are injecting into the RCS when RCS pres-sure decreases to approximately 200 psig by reading FI DH2B and FI DH2A on C5716. No throttling of the LPI valves is required if both LPI pumps are in operation since mechanical stops are installed on the cooler outlet valves. Assure proper LPI opera-tion per Section 9 of SP 1104.04, "LPI Operating Procedure".
3.4.3 If a DH Pump has failed and a break does not exist outside of containment, close the suction on the disabled pump, open DH831 or DH830, and balance flows using DH14A and DH14B if available or DHlA and DHlB if DH14A and DH14B cannot be throttled.
3.4.4 Stop any non essential equipment such as reactor coolant pumps, makeup pumps, etc. Although the'RCPs will probably trip on a loss of CCW and seal injection, DO NOT STOP MORE THAN ONE RCP PER IDOP UNLESS A MINIMUM OF 3000 gpm TOTAL DECAY HEAT FLOW HAS -
BEEN ESTABLISHED.
3.4.5 See attached sheet 3.4.6 See attached sheet 3.4.7 See Section 4.0 of this procedure for guidance before overriding any other safety equipment.
3.4.8 Monitor RB pressure and temperature and if CS Pumps are in opera-tion, assure CS 1530 and CS 1531 throttle when recirculating f rom the emergency sump.
3.4.5 Before the BWST level reaches 8 feet requiring a transfer of pump suction from the BWST to the emergency sump, the HPI pumps must either be stopped or placed in the piggyback mode of operation.
If LPI flow is less than 1000 gpa per pump, put the HPI pump in the piggyback mode by opening the LPI to hPI cross-connect as per Section 11 of the DH and LPI Operating Procedure, SP 1104.04.
If LPI flow is greater than 1000 gpa per pump, stop the HPI pumps prior to making the transfer to the emergency sump.
3.4.6 Begin monitoring BWST level on LI1525A, B, C, and D and manually transfer pump suction to the emergency sump when the BWST level reaches 8 feet.
Transfer pump suction to the emergency sump by blocking SFAS incident level 2 for DH9A and DH9B cnd then opening DH9A and DH9B using HISDH9A and HISDH9B. Verify that the BWST outlet valves DH7A and DH7B start to close as DH9A and DH9B start to open.
Verify the transfer is complete by check-ing the indicating lights on DH7A and B and DH9A and B and by checking that low pressure injection flow has NOT substantially changed.
NOTE: SFAS incident level 5 must be tripped (at 8 feet BWST level) before the transfer will work. The annunciator "BWST LO LO LVL XFER TO EMER SUMP" provides the operator assurance that the trans-fer is possible, but since this alarm may NOT be relied upon to work, continue to attempt the transfer until completed.
(See Section 2.6.7 for further explanation of this interlock.)
i l
I
(
i l
=-
ATTACHMENT C Present Circuit Configuration,
1 At present, under normal operating conditions, the BWST Outlet Valve is ep::. and the Cantainment Emergency Sump Valve is closed. With no SFAS level 2 or level 5 signals present, an interlock (contact 14-33/ac) from the BWST Outlet Valve will prevent the j
"0 PEN" circuit for the Containment Emergency Sump from being operated unless the BWST Outlet Valve is fully closed.
On e level 2 SFAS actuation, the KA and KB contacts from the SFAS will close in the "0 PEN" circuit for the BWST Outlet Valve and open in the "CLOSE" circuit.
In order to close the valve at this point, the SFAS level 2 will have to be blocked and then the valve can be moved manually.
For the Containment Emergency Sump Valve, the operation of the KA and KB SFAS contacts is similar to those in the BWST Outlet Valve circuit cxcept that the SFAS contact will insure that the valve remains closed.
4 A isvel 5 SFAS signal will affect the KC and KD contacts in both circuits. At present, l
in the BWST Outlet Valve circuit, the KC and KD contacts would open in the "0 PEN" portion of the circuit, blocking the level 2 signal.
In the "CLOSE" circuit, the KC cnd KD contacts will bypass the KA and KB contacts and automatically close the valve.
At the same time the KC and KD contacts will open in the "CLOSE" tircuit of the Containment Emergency Sump Valve, blocking the level 2 SFAS signal which will keep that j
valva closed. In the "0 PEN" circuit of the valve, KC and KD contacts will bypass the KA end KB contacts and the interlock between the two valves.
This will allow the automatic opsning of the Containment Emergency Sump Valve.
Proposed Circuit Con figuration Undar the proposed modification, the KC and KD contacts in the BWST Outlet Valve "0 PEN" l
1 circuit will remain, blocking the level 2 SFAS signal when a level 5 trip occurs. The KC cnd KD contacts in the "CLOSE" portion of the circuit however will be disconnected.
An interlock from the Containment Emergency Sump Valve (contact 7-33/bc) still will axist that will close this valve whenever the Containment Emergency Valve starts to opsn.
In the Containment Emergency Sump Valve circuit the KC and KD contacts will i
rsmain in the "CLOSE" circuit as is, to block the level 2 signal on a level 5 actuation.
In the "0 PEN" circuit, wires for the the KC and KD contacts will be moved in the motor J
control center so that the contacts will no longer bypass the KA and KB contacts. The oth3r side of the KC and KD interlock in the "0 PEN" circuit will be moved so that the interlock between the valves (contact 14-33/ac) - which prevencs the opening of the Containment Emergency Sump Valve until the BWST Outlet Valve is closed - will be bypsssed, allowing r.he operator to block level 2 and open the Containment Emergency Sump Valve without elosing the BWST Outlet Valve.
Th2 low level slarm which presently is on the annunciator, alarms whenever one of the fcur bistables associated with the four level transmitters on the BWST, trips. This
. clarm circuit is being modified to alarm not when the bistable trips but rather when tha two out of four output modules of the SFAS are tripped. This is the same module which controls the KC and KD relays. The modified alarm will tell the opertor to initiate a transfer at the same time as when a level 5 SFAS actuation (tripping of KC end KD contacts) occurs. The legend of the alarm will be changed so that the operator will know that he has had a level 5 actuation and that he should initiate the manual trans fer.
+
t
- -