ML20059M874
| ML20059M874 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 08/18/1993 |
| From: | Rueger G PACIFIC GAS & ELECTRIC CO. |
| To: | |
| References | |
| OLA-2-I-MFP-037, OLA-2-I-MFP-37, NUDOCS 9311190406 | |
| Download: ML20059M874 (8) | |
Text
.
D MFF 37 M FP EMW 37 Pacific Gas and Electric Company 77 Beate Street. Room 1451 GreggryM.Ruec r g; '
P0. Box 770000 f tSint;*Vice PresiJent and San Francisco CA 94177
- G96hralManager y p y3_.4)LA -.2 415/973-46S4 Nu; lear Power Generanon Fax 415!973-2313
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June 24, 1993
.4 PG&E Letter No. DCL-93-160 i7!"
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U.S. Nuclear Regulatory Commission i
E ATTN: Document Control Desk
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Washington, D.C.
20555 ne:
Docket No. 50-275, OL-DPR-80 Docket No. 50-323, OL-DPR-82 Diablo Canyon Units 1 and 2 Licensee Event Report 1-92-029-01 Fuel Handling Building Activities in Noncompliance With._ Technical Specification 3.9.12pue to Personnel Error j
Gentlemen:
PG&E is submitting the enclosed revision to Licensee Event Report (LER) 1 1-92-029 pursuant.to 10 CFR 50.73(a)(2)(1)(B) concerning fuel handling building activities conducted with the ventilation system not configured in accordance with Technical Specification 3.9.12.
This revision is being submitted to' report the results of PG&E's root 'cause i
investigation, corrective. actions for this event, a minor clarification in the safety analysis, and minor editorial comments in the other I
sections of the LER.
This event has in no way affected the. health and safety of the public.
Sincerely, AM (
Gregory M. Rueger cc:
Bobbie H. Faulkenberry Ann P. Hodgdon Mary H. Miller Sheri R. Peterson CPUC Diablo Distribution
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v LICENSEE EVENT REPORT (LER)
. AC.UT N.ME ii, ooc.E1 NuM.. n, PaoE n, DIABLO CANYON UNIT 1 0l5l0l0l0l2l7l5 1l'l 7 FUEL HANDLING BUILDING ACTIVITIES IN NONCOMPLIANCE WITH TECHNICAL SPECIFICATION 3.9.12 mtE i DUE TO PERSONNEL ERROR E*fEOT DATE ll)
LER NUMSER (S)
REPORT 0 ATE th OTHER F ACILITIE5 INVOLVED (8)
MOG DAV VR VR SEQutNTIAL REVladON MON DAY YR DOCKET NUMast (4)
NUMSIBIL NUMBEM l
DIABLO CANYON UNIT 2 l 10 23 92 92
- 0l2l9 0l1 06 24 93 0
5 0
0 0
QC G
TMIS REPORT 15 $UBMITTED PUR5UANT TO THE REQUIREMENT 5 OF 10 CFR (11) 6 IEEI x
to Cra so.nr nncom e
0l0l0 oTHER (specify in. bstract below and in text, NRC Form 366A)
UCENSEE CONT ACT FOR T648 EER OM TELEPHO*E NtJMB E R DAVID P. SISK, SENIOR REGULATORY COMPLIANCE ENGINEER
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i 805 545-4420 COMPLETE ONE UNE FOR EACH COMPONENT F AltuR$ DESCfDSED IN 7608 REPORT 1131 CQUEE SV5 FEM COMPONENT MAWFAC.
R OR A E CAUSE SYSTEM COMPONENT MANUF AC-R O A E I
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III Ill suPPtmtNT At REPORT ExPtCTED (141 EXPECTE9 SUBNISSION DATE (S ll YES (if yes, coPplete EXPECTED SUBMISSION DATE).
lX l NO ca5f nac7 (as)
On M ch 11, 1993, with Unit 2 in Mode 6 (Refueling), during an enerator walkdown, a Senior Reactor Operator discovered that fuel handling bu$1 ding'(FHB) Exhaust Fan l
E-5 was inoperable.
While reviewing this condition, PG&E determined that a dummy fuel assembly was moved in the spent fuel pool (SFP) on Mnrch *0,1993. with the FHBventilationsystem(FHBVS)notintheiodineremovaimode.
Technicas i
SpcaificationTTS)3.9.12was-notmTtwhenloadsweremovedovertheSFPwitfthe operating exhaust fan not aligned for iodine removal.
On March 18, 1993, while reviewing the March 10, event, PG&E questioned the previous interpretation of the definition of load movement in TS 3.9.12.. PG&E l
determined that previous movement of the spent fuel assembly handling tool on October 23, 1992, did not meet the requirements of TS 3.9.12.
PG&E has determined that the root cause of both events is personnel error.
The October 23, 1992, event was due to inadequate communication within the control room.
During the events on March 10 and 11, 1993, the shift foreman (SFM) was not aware that one train of the-FHBVS was inoperable due to a bus outage.
A lamacoid will be installed at both the SFP bridge and FHB cranes instructing personnel to contact the SFM immediately prior to moving loads over the SFP to verify proper.
FHBVS alignment.
In addition, an operations incident summary will be-issued.
61525/85K
LICENSEE EVENT REPORT (LER) TEXT CONTINUATION nar m uayra m v noun,wie m "cact "> eta m 0l2l9 0l1 2l"l7 DIABLO CANYON UNIT 1 0l5l0l0l0l2l7l5 92 Trav m )
1.
Plant Conditions Unit I was in Mode 6 '(Refueling) at 0 percent power during the October 23,.
1992, event and Unit 2 was in Mode 6 at 0 percent power during the March 10 and 11, 1993, events.
II.
Descriotion of Event A.
Summary:
1.
March 10 and 11, 1993, Dummy Fuel Assembly and Handling Tool Movement Events On March 10, 1993, during the Unit 2:fifth refueling outage (2R5), a load (dummy fuel assembly (DF)(FHM)) was moved about in i
the spent fuel pool (SFP)(DB), while the fuel handling building (ND) ventilation system (FHBVS)(VG) was'not in'the iodine removal ~ mode as required by. Technical Specification (TS) 3.9.12,
" Fuel Handling Building Ventilation System." On March 11, 1993, l
the spent fuel assembly (SFA) handling tool (DF)(FHM) was positioned over the dummy fuel assembly while the FHBVS was not
)
in the iodine removal mode.
l 2.
October 23, 1992, SFA Handling Tcc1 Movement Event While reviewing the TS applicability of the March 10 event, PG&E reevaluated the definition of a load with respect to TS 3.9.12.
As a result of this reevaluation, PG&E determined that on October 23, 1992, during the Unit 1 fifth refueling outage I
(IRS), movement of the 9 handling tool over the SFP, with FHBVS Exhaust Fan E-5 (VG)(FAN) cleared and FHBVS Exhaust Fan E-6 (VG)(FAN) not in the iodine removal mode, was a violation of TS 3.9.12 requirements.
B.
Background:
Final Safety Analysis Report (FSAR) Update Section 9.4.4.2 indicates that the iodine removal mode of FHBVS operation is required when there is a potential for radioactive particulates and/or radioactive gases in the exhaust air of the FHB. The iodine removal mode routes all exhaust air through roughing filters (VG)(FLT), high efficiency particulate air filters (HEPA)(VG)(FLT), and activated charcoal (VG)(ADS) filters. The system has redundancy for all essential, nonstatic components. When not manually selected, the iodine removal mode of ventilation is automatically initiated'by a radiation detector.
61525/85K
LICENSEE EVENT REPORT (LER) TEXT CONTINUATION
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DIABLO CANYON UNIT 1 015 l 0 l 0 l 0 l 2 l 7 l 5 92
- 0l2l9 0l1 3l'l7 TOT (17)
TS 3.9.12 requires that, with one FHBVS exhaust fan inoperable, fuel movement within the SFP or crane operations with loads over the SFP may proceed provided the operable exhaust fan is in the iodine removal mode.
TS 3.9.12 also requires that, with no FHBVS. exhaust train l
operable, movement of fuel or crane operation with loads over the SFP i
be suspended.
C.
Event
Description:
On March 10, 1993, at 0100 PST, a tailboard was held to discuss the movement of the dummy fuel assembly from the Unit 2 new fuel elevator (DF)(FHM) to the upender (DF)(FHM).
The shift foreman (SFM) had been previously contacted and he confirmed that the FHBVS alignment was acceptable for the planned activity. The FHBVS was aligned in the normal, non-iodine removal mode.
On March 10, 1993, at 0130 PST, FHB pressure was verified to be approximately negative 0.175-inch H,0, greater than the negative l
1/8-inch (0.125") H,0 required by TS 3.9.12.
At-0200 PST, the dummy fuel assembly was moved from its SFP storage rack (DB)(RK) location to l
the new fuel elevator using the SFA handling tool.
l On March 11, 1993, at 0600 PST, the SFA handling tool was positioned over the dummy fuel assembly. At the same time the refueling senior reactor operator (SRO) was walking down the equipment necessary for fuel handling operations.
The refueling SR0 discovered that the FHBVS Exhaust Fan E-5 inlet vane was failed open (the fan was inoperable due to the scheduled Bus F (EB)(BU) outage that began on March 8, 1993);
and, although the TS required negative pressure was met, the operating FHBVS exhaust fan was not in the iodine removal mode.
The FHBVS was in the normal m. ode with Exhaust Fan E-4 (VG)(FAN) operating. With Exhaust Fan E-5 inoperable, TS 3.9.12, Action a. was applicable; therefore, the FHBVS should have been in the iodine removal mode prior l
to moving the SFA handling tool over the SFP..
Since the FHBVS was aligned to the normal mode during the dummy fuel assembly movement on l
March 10 and the SFA handling tool movement on March 11, the requirements of TS 3.9.12 were not met.
l The FHBVS was placed in iodine removal mode and the SFA handling tool was secured per direction from the SFM and refueling SRO.
System Engineering personnel checked the ventilation system to confirm the operability of the iodine removal function and determined it to be acceptable. The dummy fuel assembly was moved to the new fuel l
elevator and the SFA handling tool was returned to its bracket.
On March 18, 1993, while reviewing the March 10 and 11, 1993, conditions, PG&E questioned the previous interpretation of the definition of load movement in TS 3.9.12.
PG&E concluded that any load that required use of the FHB crane (DF)(FHM) was.a load per 61525/85K
l' LICENSEE EVENT REPORT (LER) TEXT CONTINUATION a
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- 0l2l9 0l1 ' 4 l"l 7 itat (17)
A review of operating history.. identified that,.on l
October 23, 1992, the SFA handling tool was lifted with the crane for j
cleaning and inspection.
PG&E conservatively determined that this l
movement of the SFA handling tool also was movement of a load-and the requirements of TS 3.9.12 were not met at that time..
D.
Inoperable Structures, Components, or Systems that Contributed to the Event:
{
l None.
E.
Dates and Approximate Times for_ Major 0ccurrences:
1.
October 23, 1992:
Event date. The SFA handling tool was lifted with the FHB' crane.for inspection, with FHBVS Exhaust Fan E-5 cleared'and FHBVS Exhaust-Fan E-6 not in'the iodine removal mode.
2.
March 10, 1993, at 0130 PST:
FHB pressure was verified by Reactor' Engineering to be greater l
than negative 1/8-inch (0.125")
H,0 (approximately negative 0.175-inch H,0).
3.
March 10, 1993, at 0200 PST:
Event date. ine dummy fuel j
assembly was moved from SFP rack' l
location N-37 to the new fuel l
elevator using the SFA handling-l tool. 'TS 3.9.12 was not met 'since l
the FHBVS was'not in the iodine i
removal mode.
4.
March 11, 1993, at 0600 PST:
Event date/ discovery date.
Th'e l
SFA handling tool-was positioned i
over the dummy fuel assembly.
FHBVS Exhaust Fan E-5 was identified as inoperable due to l
Bus F outage.
5.
March 11, 1993, at 0615 PST: The FHBVS was placed in iodine j
removal mode until the SFA handling tool was secured.
F.
Other Systems or Secondary Functions Affected:
l l
None.
6152S/85K
LICENSEE EVENT REPORT (LER) TEXT CONTINUATION FLCILITT hAME (3)
DOCKET ht M8ER (2)
L(R NUMBER i S)
PAfe( (3) (5" vtan sn w su nsvunn DIABLO CANYON UNIT 1 0l5l0l0l0l2l7l5 92
- 0l2l9 0l1 5 l 'l 7-Itzi (in G.
Method of Discovery:
On March 11, 1993, during an operator walkdown, an SR0 discovered that i
FHBVS Exhaust Fan E-5 was inoperable. While revi
'. i this condition, PG&E determined that a dummy fuel assembly was 't:..aao in the SFP on l
March 10, 1993, and the SFA_ handling tool on March 11, 1993, with the FHBVS not in the iodine removal. mode.
)
On March 18, 1993, while reviewing the March 10 and 11, 1993, conditions, PG&E questioned the previous interpretation of the definition of load movement in TS 3.9.12.
PG&E conservatively l
determined that movement of the SFA handling tool on October 23, 1992, also was movement of a load and the requirements of TS 3.9.12 were not met at that time.
H.
Operato. Actions:
On discovery of the March 11, 1993, FHBVS condition, Operations placed the FHBVS in the iodine removal mode. There were no additional operator actions related to the October 23, 1992, event.
i I.
Safety System Responses:
None required.
III Cause of the Event A.
Immediate Cause:
The immediate cause for both the event on October 23, 1992, and the March 10 and 11 events"is movement of a lonti over the SFP withour an FHBVS train in the iodine removal mode.
- S.
Root Cause:
The root cause of the events on March 10 and 11,1993, was personnel i
error (cognitive), in that there was inadequate communication within i
the control room between the SFM and the outage assistant SFM.
The root cause of the event on October 23, 1992, was also personnel i
error (non-cognitive), in that the SFM was not aware that one train of i
the FHBVS was inoperable due to a scheduled vital Bus F outage.
j IV.
Analysis of the Event i
The FSAR Update analyzes a fuel handling accident in which a. fuel assembly is dropped on another fuel assembly.
In analyzing the potential for other fuel handling accidents for comparison with FSAR Update cases, it is-considered far more credible that a fuel assembly could be damaged by being 6152S/85K
UCENSEE EVENT REPORT (LER) TEXT CONTINUATION
~m m;33; m
- . n.uun,we w wem ma m DIABLO CANYON UNIT 1 0l5l0l0l0l2l7l5 92
- 0l2l9 0l1 6l"l7 TEAT (17) dropped against a sharp edge rather than sustaining damage while in the storage rack due to a dropped load. Therefore, the FSAR Update expected case assumption of 17 damaged rods would conservatively bound the potential l
source term from a dropped insert handling tool.
The FHBVS has two modes of operation. The normal mode exhausts air through roughing and HEPA filters and Fan E-4 without flowing through a charcoal filter, and t'ie iodine removal mode exhausts air. through the roughing and HEPA filters and either Fan E-5 or E-6, with air. flow also through charcoal filters. When not manually selected, the iodine removal mode of ventilation is automatically initiated by a radiation detector (IL)(MON). Since negative building pressure was maintained throughout the event, unfiltered leakage from the building would not have occurred.
If an accident had occurred, the FHB radiation detector would have detected any significant iodine activity and the FHB exhaust air flow would have automatically shifted to the iodine removal mode. Therefore, the radiological consequences of a load drop accident would have been conservatively bounded by the FSAR Update expected case fuel handling accident.
The resulting postulated fuel rod failures provide the source term for determining the potential site boundary dose for the March 10 and 11 and October 23 events. During'the March 10 and 11 and the October 23 events, the dummy fuel assembly and the SFA handling tool, respectively, were not handled over fuel, and if dropped would not have impacted any fuel assemblies. Thus, had an accident occurred during the described events, the resulting plant and site boundary exposures would be bounded by accidents previously analyzed in the FSAR Update.
Therefore, the health and safety of the public were not adversely affected t., these events.
)
i V.
Corrective Actions A.
Immediate Corrective Actions:
For the March 10 and 11, 1993, events, the FHBVS was placed in'the iodine removal mode. There were no immediate corrective actions for the October 23, 1992, event.
B.
Corrective Actions to Prevent Recurrence:
1.
Lamacoids will be installed for the SFP bridge and FHB cranes instructing personnel to contact the SFM immediately prior to moving loads over the SFP to verify proper FHBVS alignment.
2.
An operations incident summary will be issued to emphasize the importance of proper FHBVS alignment for FHB load movement activities.
6152S/85K
l LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Ft.CILITV NAME (1)
DOCKET NUDGER (2)
LER NUM8f8 i 6) -
PAGE (3)g,
{-
vtAn se eat at i
0l2l9 0l1 7 l 'l' 7 DIABLO CANYON UNIT 1 0l5l0l0l0l2l7l5 92 f(IT (17)
VI.
Additional Information -
A.
Failed Components:
None.
B.
Previous Similar Events:
None.
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