ML20041G423
| ML20041G423 | |
| Person / Time | |
|---|---|
| Site: | Point Beach  |
| Issue date: | 03/16/1982 |
| From: | Fay C WISCONSIN ELECTRIC POWER CO. |
| To: | Clark R, Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| TASK-2.E.1.1, TASK-2.E.1.2, TASK-TM TAC-11692, TAC-11693, NUDOCS 8203220254 | |
| Download: ML20041G423 (5) | |
Text
r 1
WISCONSIN Electnc a com 231 W. MICHIGAN, P.O. BOX 2046 MILWAUKEE. WI 53201 March 16, 1982 to Mr. H.
R.
Denton, Director O
Office of Nuclear Reactor Regulation RECT,:jyqD 1
U.
S. NUCLEAR REGULATORY COMMISSION D'
MAR 2 21982> Te Washington, D. C.
20555
\\
W stfu aerry,m Attention:
Mr. R. A. Clark, Chief s
haea nsem a "8
Operating Reactors, Branch 3 6
Gentlemen:
a DOCKET NOS. 50-266 AND 50-301 AUXIL1ARY FEEDWATER AUTOMATIC INITIATION POINT BEACil NUCLEAR PLANT, UNITS 1 AND 2 In February, Mr. T.
Colburn of your staff forwarded to Wisconsin Electric a follow-up question to our letter of September 16, 1981 regarding the automatic initiation features of the auxiliary feedwater system (AFWS) at the Point Beach Nuclear Plant.
The question was as follows:
"Are there any conditions which could prevent the AFWS from responding to an automatic start signal (e.g.,
system bypass, disabling condition, deliberately rendered inoperative, etc.) that are not continuously annunciated (audible and visible) in the main control l
room to alert the operator to the degraded status of the AFWS?
If yes, list these conditions and provide justi-l fication for not providing annunciation."
1 l
On March 2, 1982, Messrs. C. W. Krause and J. C. Reisenbuechler of my staff discussed our response to this question with Messrs. Colburn and Kendall of the NRC and Mr. Vosbury of Franklin Research Centc ;
Mr. Colburn requested that we document the discussion with a letter.
Following, therefore, is a synopsis of the items discussed during the March 2 telephone call, t
l 1.
One AFWS initiation disabling condition which occurs as a result of monthly periodic testing is the block of one of the automatic auxiliary feed pump start 0 3220254 820316 p
ADOCK 05000266
[
M r. II. R. Denton March 16, 1982 signals originated by the steam generator low-low level reactor trip two-out-of-three logic matrices.
Both trains of the reactor protection system contain this matrix for each steam generator.
Each matrix can cause a reactor trip and start one motor-driven auxiliary feed pump and the steam-driven auxiliary feed pump.
The block of the automatic auxiliary feed pump start signal occurs only during testing of these matrices.
To cause the block, a master test switch must be positioned to test the matrix and one of three momentary closure pushbutton test switches must be depressed.
Depressing the pushbutton energizes a test relay that simulatos a steam generator low-low level bistable trip signal to one of the matrix relays.
To prevent an actual auxiliary feed pump start when the reactor trip matrix logic is met (two-out-of-three pushbuttons depressea), contacts on each test relay open to block the start signal anytime the test relay is energized.
The steam generator low-low level channel alert annunciator and the matrix relay status lights provide indications on the main control board when the block exists.
These indications are activated whenever one of the matrix relays is in the tripped condition which occurs anytime the test relay is energized.
Features that should be noted about this are:
a.
Only one steam generator low-low level reactor trip matrix in one train of the reactor protection system is tested at a time.
The matrices not being tested in either train are capable of providing an automatic auxiliary feed pump start signal.
Thus, both motor-driven pumps and the steam-driven pump will receive an auto start signal should conditions require it.
b.
Placing a train of the reactor protection system in the condition required for testing does not block any automatic auxiliary feed pump start signals.
c.
The time the automatic auxiliary feed pump signal is blocked during testing is minimal at about five to ten seconds per month per steam generator low-low level matrix.
Mr. II. R. Denton March 16, 1982 d.
It is not possible to inadvertently leave the automatic auxiliary feed pump start signal blocked.
c.
The automatic start signal to the motor-driven auxiliary feed pumps from the safety injection system is not blocked while testing the steam generator low-low level reactor trip matrix.
f.
The automatic start signal to the motor and steam-driven auxiliary feed pumps from less of main feed pumps or undervoltage on the A01 and A02 busses is not blocked while testing the steam generator low-low level reactor trip matrix.
2.
An additional disabling condition which occurs as a result of plant status changes is the block of the motor-driven auxiliary feed pump start from loss of both main feed pumps (breakers open) or from steam generator low-low level.
This block is required to allow the plant to go to a condition where both main feed pumps must be secured and/or a low-low level in the steam generators is expected (usually cold shut-down or refueling shut-down).
By placing both main feed pump control switches in the pull-out position, this block is created.
No alarms on the main control board are activated when this block is established.
During a plant cool-down, the procedure used to establish this block is to start both motor-driven auxiliary feed pumps manually, verify auxiliary feed flow to both steam generators exists, secure both main feed pumps and place them in pull-out.
The motor-driven pumps are secured when the steam generators are no longer needed to remove decay heat and level is appropriate.
This block is removed during the secondary plant start-up as soon as a main feed pump is started.
Until that time, the motor-driven pumps are operating by a manual start.
Features that should be noted about this design are:
a.
The block affects only the automatic start signal to the motor-driven auxiliary feed pumps from steam generator low-low level or from loss of both main feed pumns.
b.
The block does not affect the automatic start signal to the steam-driven auxiliary feed pumps from the steam generator low-low level or under-voltage on the A01 and A02 busses.
Mr. H.
R. Denton
~4-March 16, 1982 c.
The block does not affect the automatic start signal to the motor-driven auxiliary feed pumps from the safety injection system.
d.
This block is used only when little or no decay heat needs to be removed by the steam generators.
3.
Alarms associated with the auxiliary feed pumps:
CONTROL BOARD ALARM TITLE LOCATION WINDOW PUMP i
Unit 1 Shut-Down C01 D 4-5 P38A Equipment Local Control Unit 2 Shut-Down C01 C 4-7 F38B Equipment Local Control Motor Breaker Trip C01 D 3-4 P38A&B Condensate Storage C01 A 4-7 1&2P39, l
Tank Level High-Low P38A&B I
Plant Thermocouple 1C04 1C 4-6 1P29, P38A&B l
Monitor (Unit 1) pump bearing temperature Plant Thermocouple 2C04 1c 4-4 2P29 Monitor (Unit 2) pump bearing temperature One alarm identified during this call which we believed to be associated with the motor-driven auxiliary feed pumps was the Unit 1 and Unit 2 safeguards equipment locked-out alarms.
In actuality, if the motor-driven feed pumps control switches are placed in pull-out, no alarm is received on the main control board as previously reported.
4.
One additional disabling condition is the throttle valve trip feature on the steam-driven auxiliary feed pump.
This concern was not discussed during the telephone call.
If the throttle valve is in the tripped condition, steam cannot be admitted to the pump on an automatic start.
There are throttle valve status lights on 1&2CO3 which indicate if the valve is tripped or open.
No alarms are associated with these status lights.
Mr. H. R. Denton March 16, 1982 5.
Ancther di.='*
ng condition not discussed during the telephone c-.1 is the closure of the auxiliary feed pump discharge valves.
The valves are cycled monthly for periodic testing.
Should a valve be closed, the valve status lights on 1&2CO3&Ol would indicate its closed position.
There is no alarm associated with this valve position.
Should the pump start automatically, the absence of flow as indicated on the individual steam generator auxiliary flow meter would alert the operator to this condition.
All of the items listed above are indicated or alarmed in the control room.
Those items not alarmed are items associated with the normal system line-up and the operators are trained to check the control boards for items out of the normal line-up configuration.
The operator is also trained to verify operability of the system during emergency conditions and should a system not perform as expected he is trained to quickly diagnose and correct the problem.
Please contact us if you have any questions regarding this summary of the discussion or any additional concerns regarding this subject.
Very truly yours, l
Gs'
'?
"$ () l Assistant Vice President C. W. Fay Copy to NRC Resident Inspector
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