ML19338D570
| ML19338D570 | |
| Person / Time | |
|---|---|
| Site: | Farley  |
| Issue date: | 09/12/1980 |
| From: | Clayton F ALABAMA POWER CO. |
| To: | Tedesco R Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8009230465 | |
| Download: ML19338D570 (4) | |
Text
_
Alabar'na Power Company 600 North 18th street Post Offke Box 2641 Birmangham. A!abems 35291 Telephone 205 250-1000 F. L. CLAYTON. JR.
m senior Vice President Alabama Power the southem electrc system September 12, 1980 Docket No. 50-364 Director of Nuclear Reactor. Regulation U. S. Nuclear Regulatory Commission Washington, D. C.
20555 Attention: Mr. R. L. Tedesco JOSEPH M. FARLEY NUCLEAR PLANT - UNIT 2 ENGINEERED SAFETY FEATURES BYPASS, 0VERRIDE, AND RESET CIRCUITS Gentlemen:
As requested by your letter of August 25, 1980, Alabama Power Company submits the enclosed infonnation regarding item 030.1.
If you have any questions concerning this item, please advise.
Yours very truly, L
1 FLCjr/BDM:rt Enclosure cc: Mr. R. A. Thomas Mr. G. F. Trowbridge Mr. L. L. Kintner Mr. W. H. Bradford SON l(
l I
8 0 0 9 2 3 ON/p5 g
u
==
a g
Y I,
~
+
7y
.. e.
' 030.'1 : 'P0TENTIAL DESIGN DEFICIENCIES'IN BYPASS, DVERRIDE,
~
' AN0' RESET CIRCUITS OF ENGINEERED SAFETY: FEATURES
~ REQUEST TheWrriding of certain containment: ventilation isolation signals could talso; bypass other safety actuation signals and thus prevent valve; closure-Ewhen the other isolation signals are present.
Although such designs may. -
' be acceptable, _ and even;necessary, to accomplish certain' reactor _. functions, they are generally unacceptable)here they result in the unnecessary'by-inassing of safetyzactuation signals.;1Where such bypassing;is'also inadvertent..
a more serious situation:is created.expecially where there.is~no bypass-
~
- indication system toialert the. operator.:
Where the resetting'of ESF ' actuation signals, such as safety ' injection, directly causes equipment-important to safety to return to its.non-safety.
mode,. protective actions of the~ affected' systems could be prematurely.
negated when:the associated actuation. signal is reset.
Prompt operator-action.would be required to assure that the'necessary equipment 11s returned.
to its emergency mode; The use of non-safety grade monitor to inititte containment isolation' could seriously degrade the reliability of the isoiation system.
STAFF POSITI'ON "It is-our position that,'in addition to other applicable criteria, the
~
following should be satisfied for all operating license applications currently under review:
- 1) The overridinga of one type of safety actuation-signal (e.g., particulate radiation) should not cause the blocking of any other type of safety.
actuation -signal (e.g', iodine radiation,. recator pressure).
- 2) Physical -features -(e.g., key _ lock switches)'should be provided to ensure 3
adequate administrative controls.
3)
A' system level annunciation of the overridden status should be provided
. for every safety: system impacted when any override is active.
(See R.G. 1.47.)-'
s 4)_ The following diverse signals should be.provided to initiate isolation-of the containment purge / ventilation system: containment high radiation.
safety: injection. actuation, and containment high pressure (where _ con-
.tainment;high pressure is not a portion of safety injection actuation).
'S) The ? instrumentation systems provided to initiate cortainment purge
' ventilation isolation should be designed and qualified to Class IE criteria.
_a0verride: 5The signal ~is_still present, and it is blocked in 2
iorder;.to perfonn a function contrary to the signal.
- 11 t
~
g 7
~
t
.,0 g
+
t i, ~ -
'i.
m m
d
m o
P b
- 6) The overriding or resetting of the ESF actuation signal should not cause any equipment to change position.
Accordingly, you are requested to review your protection system' design to determine its degree.of conformance to.these criteria. You should report the results of your revfew to us describing any departures from the criteria and the corrective actions to be impicmented. Design departures for which no corrective action is planned should be justified.
RESP 0fiSE POSITI0tt 1 All containment isolation valves required to automatically close under accident conditions have been reviewed at the schematic / elementary diagram level and no case was found in which the overriding of one type of safety actuation signal would cause the blocking of any other type of safety act-uation signal.
POSITI0flS 2 and 3 These two positions are not applicable as a result of the response to POSITI0t1 1.
..P0SITI0ft 4 Two diverse signals are provided to initiate isolation of the containment purge system: high radiation and containment ventilation isolation (safety injection actuation).. Containment high pressure is part of the containment ventilation' isolation signal.
'POSITI0tl 5 The instrumentation systems provided to initiate containment purge vent-ilation isolation are designed and qualified to Class lE criteria.
POSITI0ft 6 We have previously reviewed at the schematic / elementary diagram level all i
safety related components actuated by any type of safety signal generated j
by the solid state protection system and provided with retentive memory and
' manual reset ' capability.
j The purpose of the review was to determine wheth>r 'or not following the manual 1 reset of any.of the safety actuation signals, all associated safety related equipment remains in its emergency mode. During this review there were three cases in which the manual reset of the safety signal would result j
bReseti The signal has come and gone,' and the circuit is b'eing
~
cleared in order to return it to the normal condition.
-2_
2
=
s-
.. e in equipment not remaining in the emergency mode. The motor driven auxiliary feedwater pump discharge valves are controlled from the main control room with a three position (open, close, modulate) maintained contact switch and a separate hand controller used to vary the valve position in.the modulate mode. The only case in which manual reset of. the safety injection signal would result in the~ valves not remaining in the emergency mode is when the switch is in the modulate position. With the switch in the modulate position, under a cafety injection signal the valve will go full open.
valve will return to the modulate moAtAfter resettig the safety injection, the at the pre-safety injection manual controller position. To ensure that the valves remain in the emergency mode after reset of a safety injection signal, the auxiliary feedwater discharge valve control circuitry will be modified so that an auxiliary feedwater reset capability (reset switches will be located on the main control board) is provided. This modification will require the operator to manually reset the safety injection signal and the auxiliary feedwater -
seal-in circuitr emergency mode (y before the discharge valves can be moved from.their valves opened).
The containment post-LOCA air mixing fans are designed to automatically.
start five minutes after receiving a safety injection signal.
If the safety injection signal is reset prior to the completion of five minutes, the fans will not start. The starting circuitry of the fan will be modified so that upon receiving a safety injection signal the fans will start even if the safety. injection signal is reset prior to five minutes.
With the cont"
'ent purge damper switches in the mini-purge or full purge v posit b ; J.
r- -
of a containment ventilation isolation signal.. mainment purge isolation d Following the reset of the l
containment ventilation isolation signal, the corresponding dampers will The control circuitry of the containment purge isolation dampers reopen.
will be modified so that upon reset of the containment ventilation signal the dampers will not reopen.. Separate individual hand switch operat;on is required.
The containment post-LOCA air mixing fan, the containment purge isolation damper, and the auxiliary feedwater discharge valve modifications will be implemented prior to operation above zero power.
- A f.
- -