ML20059M680
| ML20059M680 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 08/20/1993 |
| From: | Rueger G PACIFIC GAS & ELECTRIC CO. |
| To: | |
| References | |
| OLA-2-I-MFP-F2, NUDOCS 9311190237 | |
| Download: ML20059M680 (10) | |
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/ Pacific Gas and Dectric Company 77 Beate Street Gr:geryM Ru?;r San Francis 0 CA 94106 Senor vice PresmT E :
415/973-4684 General Manage C ED 3;pg Nuclear Power Gener3po.a October 7, 1992 g g g gg yfh PG&E Letter No. DCL-92-214 g'3,t F-2 U.S. Nuclear Regulatory Comission $ in
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ATTN:
Document Control Desk p ggp 8[
g4 Washington, D.C.
20555 Re:
Docket No. 50-275, OL-DPR-80 Diablo Canyon Unit 1 Licensae Event Repo-' l-92-014-00 Violation of Technical Specification 3.7.10: Missed Fire Watches Due To Personnel Error ~
Gentlemen:
Pursuant to 10 CFR 50.73(a)(2)(1)(B), PG&E is submitting the enclosed Licensee Event Report concerning a violation of Technical Specification 3.7.10 due to missed' fire watches caused by personnel error.
This event has in no way affected the health and safety of the public.
Sincerely, f
<% J. wp Gregory M. Rueger cc:
Ann P. Hodgdon John B. Martin Philip J. Morrill Harry Rood CPUC Diablo Distribution INPO DCl-92-SS-N040
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Enclosure 1056S/85K/TDB/2246
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i UCENSEE EVENT REPORT (LER) 197328 eacam ma ni oocu,== m
,,, m DIABLO CANY3N UNIT 1 0l5l0 0l012l7l5 1 "I 9 mu. VIOLATION OF TECHNICAL SPECIFICATION 3.7.10: MISSED FIRE WATCHES DUE TO PERSONNEL ERROR evuwt oara m un numasan m as=ont u ts m ornia vac Livits swvotyto te>
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On September 3, 1992, at 1630 PDT and on September 4, 1992, at 1630 PDT, with Unit 1 in Mode 1 (Power Operation) at 87 percent power, and on September 15, 1992, at 1032 PDT, with Unit 1 in Mode 5 (Cold Shutdown), the Limiting Condition for Operation (LCO) of Technical Specification (TS) 3.7.10 was exceeded when a continuous fire watch was not in place while smoke detectors were inoperable and fire barrier impairments existed in the detecuon zone.
The first two events were identified on September 10, 1992, when a review of a fire barrier impainnents list determined that fire barrier impairments had existed that were not resolved by 1630 PDT on September 3 and 4, 1992.
The root cause for events 1 and 2 was personnel error (non-cognitive) in that operations personnel failed to understand the interrelationship between the faulted detection zone and the fire barrier area when interpreting the compensatory measures specified in TS 3.7.10.
The root cause for event 3 was personnel error (cognitive) in that the Unit 2 operator did not clearly inform Unit I personnel of the Zone A10 alarm status.
The corrective actions include revision of applicable procedures to: (1) more accurately reflect the status of field construction activities that impact fire barriers; (2) clarify the effect of alarming detectors; and (3) clarify the impact that an inoperable fire detector has on compensatory measures for fire barrier impairments.
In addition, training will be provided on the events.
10565/85K
O LICENSEE EVENT REPORT (LER) TEXT CSNTINUATION gg g g me,a.
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C.
Event
Description:
On September 3, 1992, at 1037 PDT, a faulty smoke detector in Zone A10 went into alarm. A plant problem report was initiated to identify and' correct the problem. Due to ongoing block wall construction work in
.J the area, a daily continuous fire watch was in place at the time of i
the alarm indication.
On September 3, 1992, at 1630 PDT,'the Limiting Condition for Operation (LCO) action statement a..of TS 3.7.10 was exceeded when'the i
daily block wall construction activities were completed _ and the compensatory me'asure was' relaxed from the continuous fire watch to an' hourly roving fire watch (event 1). However, unknown to the Shift Foreman, untracked fire barrier impairments still-existed and the-Zone A10 detection system was-inoperable due to the continuous alarm i
from the faulted smoke detector and the lack of reflash capability.
On September 4,1992, at 0600 PDT, the hourly fire watch was replaced by the continuous fire watch because of ongoing block wall modifications.
On September 4,1992, at 1630 PDT, TS 3.7.10 was again exceeded when the daily block wall construction activities'were completed and the -
2 compensatory measure was relaxed from the continuous fire watch to an i
hourly roving fire watch (event 2). At 1857 PDT, a concern was raised f
by the Shift Foreman about the adequacy of the roving hourly fire watch in the area with the faulty detector. At 2000 PDT, a test 1
verified that reflash for the Zone A10 smoke detectors was not available. A continuous fire watch was established at'2100 PDT who remained there until the faulty smoke detector was repaired at
)
2221 PDT. Discussions with fire protection personnel indicated that all applicable fire barrier impairments listed on the TS fire '. crier u
impairment tracking sheet had been resolved prior _to 1630 PDT, therefore no TS violations were believed to have occurred on September 3rd and 4th.
On September 10, 1992, at 1500 PDT, further investigation determined that some fire barrier impairments that were not tracked by the,TS fire barrier impairment tracking system existed on September.3rd and 4th and, therefore, the conditions noted above were TS violations, contrary to what the fire protection personnel had previously thought.
On September 15, 1992, at 0932 PDT, a detector in Zone A10 went into alarm. A Unit I operator acknowledged the main annunciator alarm and by previous agreement between the Unit l_ and Unit 2 control room:
personnel due to the Unit I fifth refueling outage, a Unit 2. operator went to investigate the cause of the alarm. The Unit 2 operator determined that no fire existed and the alars could be due to cleaning dust from a transformer (XFMR) or. heat gun usage in an electrical panel (PL). The Unit 2 operator returned to the control room 'and reported to the Unit 1 personnel what he had observed. The Unit 1 1056S/S5K
LICENSEE EVENT REPORT (LER) TEXT CONTINUATION 197028
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I.
Plant Conditions Unit.I was in Mode 1 (Power Operation) at 87 percent power prior to events 1 and 2 and in Mode 5 (Cold Shutdown) prior to event 3.
II.
Description of Event A.
Summary:
On September ? 1992, at 1630 PDT, September 4, 1992, at 1630 PDT, and September 15.
at 1032 PDT, the action statement for Technical Specificatioi 3.7.10 was not met for Unit 1.
The required continuous fire watch was not in place while Zone A10 smoke detectors (IC)(DET) were inoperable and Zone A10 fire barriers were impaired.
B.
Background:
TS 3.7.10 requires that with one or more required fire barrier penetrations non-functional, within I hour, either establish a continuous f' 9 watch on at least one side of the affected penetration.
verify the operability of the smoke detectors on at least one sit. of the non-functional fire barrier and establish an hourly fire watch patrol.
Fire detection Zone A10 monitors the 480 volt switchgear (ED)(SWGR) rooms for Unit 1.
Detection Zone A10 is comprised of several distinct fire areas and not only a single room.
An operator is alerted to an alarm by the control room (NA) annunciator (IB)(ANN).
The operator acknowledges.and silences the main annunciator bell, determines which zone is in alarm by observing the alarm windows on the Fire Alarm Control Panel (IC)(CBD) in the back of the control room, evaluates the condition, and takes appropriate action that may include attempting to reset the alarm to determine if the alarm is spurious.
Reflash is an equipment feature that re-initiates the control room annunciator when a subsequent alarm signal is generated.
The fire detection system uses a Honeywell process computer that annunciates j
a differently than other DCPP annunciator alarms. A red " Fire Alarm Panels Annun Acknowledge" button is provided that will extinguish the i
Main Annunciator PK 10-10 window regardless of the Fire Alarm Control Panel alarm status. Once the alarm is acknowledged by use of the red l
button, there is no feature to re-alert (reflash) the operator of the existing condition.
l Due to the ongoing masonry block wall modifications, the daily practice was to verify that the physical impairments to the fire barriers were resolved at the end of each shift before shifting from a l
continuous to a roving fire watch.
10565/85K i
1
LICENSEE EVENT REPORT (LER) TEXT CONTINUATION 197328
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.m m DIABLO CANYON UNIT 1 0l5l0l0l0l2l7l5 92 0l1l4l-l 010 4 l"l 9 18:Y (17) operator then told the Unit 1 personnel that he was going to reset the main annunciator alarm to continue performing a Unit 2 surveillance which required the use of annunciator PK 10-10. The Unit 2 operator did not make it clear that he had not attempted to reset the Fire Zone Alarm Panel and the Unit 1 operators did not check the panel themselves. Without reflash capability, Zone A10 detectors were inoperable.
The Unit 2 operator acknowledged the alarm on the Honeywell alarm system which extinguished the main annunciator light.
Since many planned evolut...is were taking place at this time for the refueling outage, the Unit I control room personnel lost track of the smoke alarm status without establishing the necessary compensatory measures.
On September 15, 1992, at 1032 PDT, the one-hour LC0 action statement
- a. of TS 3.7.10 was exceeded when a required continuous fire watch was not established while the Zone A10 smoke detectors were inoperable and fire barrier impairments existed (event 3).
On September 16, 1992, at 0710 PDT, the system engineer performed his daily review of the fire system computer print-out for the previous day and discovered that a detector in Zone A10 was in alarm.
He notified the Shift Foreman and the alarm was cleared and reset at 0719 PDT.
D.
Inoperable Structures, Components, or Systems that Contributed to the Event None.
E.
Dates and Approximate Times for Major Occurrences:
1.
September 3, 1992 at 1630 PDT:
Event 1 Date. The LCO for TS 3.7.10 action statement
- a. was not met when the daily continuous watch was replaced by an hourly fire watch.
2.
September 4, 1992 at 1630 PDT:
Event 2 Date. Daily continuous fire watch was replaced by an hourly fire watch. LCO for TS 3.7.10 action statement a. was not ret for a second time.
3.
September 4, 1992 at 2100 PDT:
A continuous fire watch was established due to fire barrier impairments in the affected area. TS 3.7.10 action statement a. was exited.
1056S/85K
197328 [*
LICENSEE EVENT REPORT (LER) TEXT _ CONTINUATION FACILITV ensret (1)
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DIABLO CANiuN UNIT 1 0l5l0!0l0l2l7l5 92 0]1l4 0l0 5 l"l 9 1(af (37) 4.
September 4,1992 at 2221 PDT:
Faulty smoke detector #10 was repaired.
5.
September 10, 1992 at 1500 PDT:
Discovery Date.for Events I l
and 2. Investigation determined fire barrier impairments ~extsted on September 3rd and 4th that were not tracked by the TS 1
fire barrier impairment tracking system.
6.
September 15, 1992 at 1032 PDT:
Event 3 Date. ' The LCO for TS 3.7.10 action statement 1
- a. was not met when a continuous fire watch was not establishec' while TS 1
l fire barrier impairments existed in the area.
7.
September 16, 1992 at 0710 PDT:
Discovery Date for Event 3.
1 System Engineer identified detector Zone A10 in alarm.
At 0719 PDT the operators reset and cleared the Zone A10 smoke detectors.
TS 3.7.10 action statement
- a. exited.
I F.
Other Systems or Secondary Functions Affected:
None.
.c G.
Method of Discovery:
Event I and 2.
The TS LCO violation was identified on September 10, 1992, when investigation determined fire barrier impairments existed-on September 3rd and 4th that were not tracked by the TS fire barrier impairment tracking system.
Event 3.
The TS LCO violation was discovered by the system engineer when he performed a daily review of the fire system corputer data.
j H.
Operators Actions:
Event 1 and 2.
On September 3, 1992; at 1037 PDT, an operator was sent to investigate the cause of the alarm and determined that there was no actual fire. On September 4, 1992, at 2000 PDT, an operator was dispatched to smoke test a detector in Zone A10 to assess the reflash capability of the system.
l 10565/85K
LICENSEE EVENT REPORT (LER) TEXT CsNTINUATION gg m
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Event 3.
On September 15, 1992, at 0932 PDT, a Unit 2 operator was sent to investigate the cause of the alarm and determined that there was no actual fire. On September 16, 1992, at 0719 PDT, upon identifying that the alarm condition still existed, a Unit 1 operator reset the alarm.
]
I.
Safety System Responses:
None.
III. Cause of the Event A.
Immediate Cause:
Events 1, 2, and 3.
Zone A10 smoke detector #10 was in alarm rendering all Zone A10 smoke detectors inoperable while some fire barrier impairments existed without a continuous fire watch.
B.
Root Cause:
Events 1 and 2.
The root cause for the events is personnel error (non-cognitive) in that operations personnel failed to understand the interrelationship between the faulted detection zone and the fire barrier area when interpreting the compensatory measures specified in the technical specifications. Also, the computerized TS fire barrier impairment tracking system did not accurately reflect the status of existing impaired barriers.
Event 3.
The root cause for event 3 was personnel error (cognitive) in that the Unit 2 operator did not notify the Unit 1 personnel of the Zone A10 alarm status.
C.
Contributory Cause:
1.
Events 1, 2, and 3.
The computer that processes the fire detection system alarms annunciates differently than other control room annunciator alarms. When the annunciator is reset at the Fire Alarm Control Panel, the main annunciator light is extinguished and there is no control board feature to re-alert the operator of the existing condition.
It is incumbent on the operator after acknowledging the alarm to investigate the cause, otherwise there is nothing on the main annunciator to remind one that the alarm exists.
l 2.
Events 1 and 2.
The fire detection computer Operation Procedure (0P) K-20, " Fire Protection Operation and Response Procedure,"
did not clearly describe the impact of an inoperable smoke i
10565/85K
LICENSEE EVENT REPORT (LER) TEXT CONTINUATION 197328 i
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DIABLO CANYON UNIT 1 0l5l0l0l0l2l7l5 92
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,01 (37) detector on the other detectors in the same zone, nor did it address the impact of an inoperable detector on existing fire barrier impairments that credit the detection system as a compensatory measure.
3.
Events 1 and 2.
DCPP training sessions do not emphasize that a smoke detector in alarm impacts the reflash capabilities of the detection system and may impact more than one fire area.
4.
Events 1, 2, and 3.
There is a deficiency within the Annunciator Response Procedure (ARP) PK 10-10. " Fire Detected."
The current sequence of actions that an operator performs when an alarm is received allows the annunciator alarm to be acknowledged, and hence silenced, before the situation is resolved.
IV.
Analysis of the Event Fire detection Zone A10 is comprised of the Unit I vital and non-vital 480 Volt switchgear rooms.
These rooms contain safe shutdown equipment associated with the 480 Volt vital power supplies and cabling / equipment associated with hot shutdown panel instrumentation and control.
The fire loading in the vital switchgear rooms -is 27 minutes of fixed combustibles and 1 minute of transient combustibles.
Thus,.the fire loading of the area is well within the design combustible loading of 33 minutes of fixed combustibles and 1 minute of transient combustibles.
The majority of the combustible loading is contained within the switchgear cubicles (wiring insulation).
In order for a fire to damage redundant safe shutdown equipment it would have te breach one of the impaired' block wall seismic gaps. The impairment to these gaps involved the removal of pyrocrete fireproofing material covering the gap.
The removal of this material does not, however, provide a direct path for fire or smoke propagation. The seismic gap is filled with a non-combustible material to retard heat or fire propagation. This material, although not specifically rated in the impaired configuration, is expected to preclude the spread of fire to redundant safe shutdown equipment due to the tortuous path that must be traveled by a fire in order to damage redundant trains.
The most likely source of a fire during the timeframes when block wall modification work was not in progress is associated with an electrical fault i
in the switchgear. During periods when block wall modification work was in
{
progress, the welding and transient combustible loads were monitored by a continuous fire watch. A fire initiated in the 480 Volt switchgear is unlikely due to the circuit protection provided by electrical system design criteria. Should a fire be initiated, however, propagation from the switchgear to the seismic gap and propagation through the 8-inch seismic gap i
through the non-combustible filler material and then propagation from the seismic gap to the redundant safe shutdown equipment / cabling would be 10565/85K i
LICENSEE EVENT REPORT (LER) TEXT CONTINUATION 197328 u.y..
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0l1l4, i 0l0 8l"l9 DIABLO CANYON UNIT 1 0l5l0l0l0l2l7l5 92 f(81 (37) required. This is considered to be highly unlikely.. In addition, a fire j
initiated in one of the switchgear rooms would result in a loss of 480 Volt i
equipment status indication and/or spurious indication, thus alerting the operators to a potential problem. This would result in detection of the fire in a timeframe that would further limit the possibility of damage to redundant safe shutdown equipment.
Further indication of potential problems in the area would have been provided by the annunciation of vital bus grounds which would be likely to occur as a result of a fire near the switchgear, as well as annuncia"an of room temperature monitors.. Thus, the missed fire watches did not adversely affect the health and safety of the public.
V.
Corrective Actions
-l A.
Immediate Corrective Actions:
)
1.
Event I and 2.
On September 4,1992, at 2100 PDT, a continuous 1
fire watch was established and at 2221 PDT, the faulty smoke detector was repaired.
2.
Event 3.
On September 16, 1992, at 0719 PDT, a Unit 1 operator successfully reset the alarm system and an operations shift j
order was issued clarifying fire detection zone reflash j
capability.
B.
Corrective Actions to Prevent Recurrence:-
1.
Nuclear Plant Administrative Procedure C-654, " Control of Equipment Required by the Plant Technical Specifications," will be revised to clarify the impact that an inoperable fire detector has on compensatory measures for fire barrier impairments.
2.
An incident summary was issued for,the missed fire watches that occurred on September 3,1992, September 4,1992, and September 15, 1992.
3.
OP K-2C will be revised to include a statement that addresses the relationship between a fire detector zone and a fire area and to clarify the fact that an alarming detector renders the detector zone inoperable. Also, OP K-2C will be revised to include plant layout drawings that depict.the fire areas,
~
detector zones, and actual detectors.
4.
Operations personnel will be retrained on the operation of the fire detection system including the alarm process computer as-well as the inter-relationship between fire detector zones and fire areas.
10565/85K
. LICENSEE EVENT REPORT (LER) TEXT CCNTINUATION 197328 't
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5.
Nuclear Plant Administrative Procedure C-113. " Fire Barrier Impairments," and the computer'ized impairment tracking program will be revised to'more accurately reflect-the status of field construction activities that-impact fire barriers.
l 6.
ARP PK 10-10 and OP K-2C will.be revised to ensure that compensatory measures-are initiated prior to extinguishing the i
PK 10-10 " Fire Detected" sain annunciator light.
- 7 VI.
Additional Information A.'
Failed Components:
l None.
B.
Previous LERs on Similar Problems:
i 1.
LER l-92-008-00, Violation of Technical Specification 3.7.9.2 Due to a Missed fire Watch Caused by Personnel Error.
The root cause was determined to be personnel error on the part of a licensed Shift Foreman. Upon reviewing the equipment tagout request, the Shift Foreman did not -identify the TS requirements.
Corrective actions included counselling the Shift Foreman and Operators involved in the importance of establishing TS required fire watches and establishing anl0perations Coordination Instruction to establish fire watches as the first step on any tagout iequest that renders TS fire protection systems inoperable. The current events did not involve a tagout request rendering a fire' protection system inoperable; therefore, the previous corrective actions would.not have a
prevented this LER.
j 2.
LER 1-91-015-00, Violation of Technical Specification 3.7.10 When An Hourly Fire Watch Patrol Was Not Performed Due To -
Inadequate Instructions.
The root cause was determined to be no written instructions existed to ensure that Technical Specifications related fire barrier impairment would'be inspected each hour during unexpected conditions that could delay fire watch personnel.
Corrective actions included written instructions to fire watch '
personnel on actions to take if delayed during rounds and an-incident sumary of the event that was reviewed by all-fire watch personnel. The current events did'not involve delayed ~
fire watch personnel; therefore, the previous corrective actions would not have prevented this LER.
1056S/85K a