ML20059M868

Intervenor Exhibit I-MFP-36,consisting of 930624 Ltr Re LER 2-93-004-01

ML20059M868
Person / Time
Site:	Diablo Canyon
Issue date:	08/18/1993
From:	Rueger G PACIFIC GAS & ELECTRIC CO.
To:
References
OLA-2-I-MFP-036, OLA-2-I-MFP-36, NUDOCS 9311190399
Download: ML20059M868 (7)

Text

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GrcgoryM.Nueger l l Pacific G4iand Electric Company 77 Beate Siree!.FooinH51

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'93 CCI 28 P6 :28 l June 24, 1993 m;- , y PG&E Letter No. DCL-93-159 we a j U.S. Nuclear Regulatory Commission  !

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ATTN: Document Control Desk

' Washington, D.C. 20555- l y  :

Re: Docket No. 50-323, OL-DPR-C:

Diablo Canyon Unit 2 Licensee Event Report 2-93-004-01 . .

Technical Specification 3.9.12 Not Met When The Fuel Handling Building Ventilation System Was Inoperable During Fuel Movement Due To Programmatic Deficiency 1

Gentlemen:

PGaE is submitting the enclosed revision to Licensee Event. Report 2-93-004 pursuant to 10 CFR 50.73(a)(2)(i)(B) concerning the violation of Technical Specification 3.9.12 due to a blocked open personnel door causing a reduced negative pressure in the fuel handling building. This revision is being submitted to report the results of PG&E's root cause  ;

investigation, corrective actions for this event, and minor editorial comments in other sections of this LER.

This event has in no way affected the health and safety of the public.

Sincerely,

, 4 A f wy --

i Gregory M. Rueger cc: Bobbie H. Faulkenberry Ann P. Hodgdon.

Mary H. Miller Sheri R. Peterson CPUC Diablo Distribution INP0 NuctEAR RECUT ATcRY COMMIS$l0N DC2-93-TP-N015 Enc 1osure vecw in : v.3 no cAcR$gA2LML 3@0-d% ~ rM m Q_:,w W& - M 6153S/85K/ALN/2246 n~

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LICENSEE EVENT REPORT (LER) TEXT CONTINUATION _

j FACIL.ITV NAME (1) DOCKET NUM6(R (2) LER NUMBER f6) PArat (3) 1

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DIABLO CANYON UNIT 2 0l5l0l0l0l3l2l3 93 -

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I I. Plant Conditions Unit 2 was in Mode 6 (Refueling) at 0 percent power during this event. ]

II. Description of Event A. Summary:

1 On March 17, 1992, during the Unit 2 fifth refueling outage (2RS), at approximately 0800 PST, an ammonia /hydrazine leak occurred on the 100 foot elevation of the fuel handling building (FHB)(ND). During this time, insert (DB) shuffle was in progress in the Unit 2 spent' fuel-pool (SFP)(DB) and the FHB ventilation system (FHBVS)(VG) was in the iodine removal mode. At 1008 FST, Technical Specification , (TS) 3.9.12 was not met when a-FHB door was propped open to dissipate fumes. -

B.

Background:

Final Safety Analysis Report (FSAR) Update Section 9.4.4.1 indicates that the requirement for the design of the FHBVS-system is to remove-more air than is supplied so that all potential air leakages will be into and not out of the FHB. The FSAR Update assumes'that the spent fuel pool area is supplied with less air than is exhausted, thus creating a negative pressure with respect to ambient. A negative pressure assures that exfiltration from the area of a spent fuel handling accident would be through the FHB exhaust.

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 FiiB and routes all exhaust air through roughing filters-(VG)(FLT), high efficiency particulate air filters (HEPA)(VG)(FLT), and activated charcoal filters (VG)(ADS). When not manually selected, the iodine removal mode of ventilation is automatically initiated by a radiation -

detector (VG)(DET).

Administrative Procedure (AP) C-66, " Control of Doors Important to l Safety," requires that an individual put into effect all compensatory I actions prior to impairing the function of any identified ventilation boundary door. In any situation where requirements are unclear, AP C-66 requires notification of the shift foreman (SFM) prior to impairing the function of a door. This procedure specifically addresses the loss of differential pressure maintenance function of FHB doors and suspension of concurrent fuel handling activities in the FHB. i I

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LICENSEE EVENT REPORT (LER) TEXT CONTINUATION - ,,

i DOCKET NUMBER (,). L(R NUMBER i6) P Ar,E (3)

FCCILITV NANC (3)

DIABLO CANYON UNIT 2 0l5l0l0l0l3l2l3 93- -

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C. Event

Description:

On March 17, 1993, at approximately 0800 PST, an ammonia /hydrazine leak from a valve (KD)(V) used in.feedwater (SJ) ' chemistry control occurred on the 100 foot elevation of the FHB.- During this time insert shuffle was in' progress in' the Unit 2 SFP and the FHBVS was in the iodine removal mode.

To permit air sampling and to assist in the dissipation of-ammonia /hydrazine fumes, personnel door 258-2-(ND)(DR) was propped open at approximately 1008 PST. The SFM was informed of the open FHB door at 1015 PST. During the time the FHB door.was open.it was attended by Operations personnel.

On March 17,1993, at 1018 PST, the fuel handling senior reactor  !

operator (SRO) checked the FHB pressure and determined it to;be _

approximately negative 0.10-inch H,0 (TS 3.9.12 requires a pressure '

l not less than negative 1/8-inch [0.125"] H,0). - Thus, Operations -

determined that the FHBVS was not in compliance with TS 3.9.12 and was inoperable. The fuel handling SRO immediately directed fuel handling.

equipment be placed in a safe configuration and informed the SFM. Thei insert shuffle was halted. The SFM recognized that the out-of-specification FHB pressure was a result of the FHB door being propped open.

l The FHB door was permitted to remain open until 1035 PST to decrease i the concentration of the ammonia /hydrazine fumes in the FHB to an acceptable amount, at which tinie the door was closed. -  ;

_ On March 17,.1993, at 1040 PST, FHB pressure was determined to be

" negative 0.22-inch H,0 and the fnsert shuffle was re's'umed. -

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During this event, from 1008 to 1018 PST, the FHB ventilation system was not considered inoperable by PG&E. operations' personnel since it l was believed that the FHB doors may be temporarily blocked open as long as they are attended. For this event, hazardous material response personnel were present the entire time the door was blocked ,

open.

D. Inoperable Structures, Components, or Systems that Contributed to the Event:

None.

E. Dates and Approximate Times for. Major Occurrences:

1. March 17, 1993, at 0730 PST: Insert shuffle commenced in the Unit 2 SFP pool with the ventilation system'in iodine i- 6153S/85K

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finT 07) removal mode (only one operable '

train of ventilation).

2. March 17, 1993, at 0800 PST: Ammonia /hydrazine leak occurred on the 100 foot elevation of the FHB..

3. March 17, 1993, at 100a PST: . Event date.. Door 258-2 was opened and attended, to assist in fume

- dissipation while insert shuffle was in progress.

4. March 17, 1993, at 1015 PST: SFM was-notified that the FHB door had been opened.

5. March 17, 1993, at 1018'PST: Discovery date. Fuel handling SRO checked the negative pressure in

.the FHB and found>it to be approximately negative 0.10-inch-H,0 (TS 3.9.12 limit is negative l

1/8-inch [0.125"] H,0) .

6. March 17, 1993, at 1021 PST: Fuel handling SR0 placed fuel handling equipment in a safe -

configuration.

7. March 17, 1993, at 1035 PST: Ammonia /hydrazine fume limits dropped to acceptable levels and '

door 258-2 was closed.

8. March 17, 1993, at 1037 PST: FHB nega61ve pressure was verified-to be negative 0.22-inch H,0.

9. March 17, 1993, at 1040 PST: Unit 2 insert shuffle in the SFP was resumed.

F. Other Systems or' Secondary Functions Affected: .

None.  !

I G. Method of Discovery:

The'SFM, when informed that the FHB personnel door was open to mitigate the ammonia /hydrazine fume concentration in the FHB, directed.

the fuel handling SR0 to determine the FHB pressure. The fuel handling SRO confirmed that TS 3.9.12 limits had.been exceeded.

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DIABLO CANYON UNIT 2 0l5l0l0l0l3l2l3 93 -

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H. Operator Actions:

The SFM was informed that the FHB door was opened while-insert l shuffling was .taking place. The fuel handling'SR0 observed FHB pressure to be less negative than rcquired by TS 3.9.12 and' halted SFP activities. Insert shuffle was resumed with the' concurrence of the-SFM when FHB pressure returned to an acceptable value.

I. Safety System Responses:

None required. -

III. Cause of the Event A. Immediate Cause:

The immediate cause of this event was maintaining FHB personnel door l 258-2 open, resulting in the TS 3.9.12 negative pressure limit being exceeded.

B. Root Cause:

PG&E has determined that1the root cause of'this event is-programmatic deficiency, in.that hazardous material response personnel were not aware that door 258-2 was a ventilation boundary for the FHB and the associated consequences of opening it.

IV. Analysis of the Event The 4el inserts were moved over spent fuel, so the potentiahfor. an x accident during this event did exist. In analyzmy the potential for fuel.

l handling accidents for FSAR Update cases, it is considered far more credible that a fuel assembly could be damaged by being dropped against a sharp edge rather than sustaining damage due to a dropped load while in the storage rack. Therefore, the " expected case" assumption of 17 damaged rods would conservatively bound the potential source term from a dropped insert l handling tool. The FSAR Update expected case also assumes decay of 100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br />; the decay time during this event was in excess of 280 hours0.00324 days <br />0.0778 hours <br />4.62963e-4 weeks <br />1.0654e-4 months <br />. Thus,

! the possible source term was bounded by the existing.FSAR Update i assumptions.

The FHBVS has two modes of operation. The normal mode exhausts air through roughing and HEPA filters and Fan E-4 (VG)(FAN) without flowing through a charcoal filter. The iodine removal mode exhausts air'through 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.

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t LICENSEE EVENT REPORT (LER) TEXT CONTINUATION -

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u. .~ ~m DIABLO CANYON UNIT 2 0l5l0l0l0l3l2l3 93 -

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Since negative building pressure was maintained throughout the event, unfiltered leakage from the FHB would not have occurred. The results of charcoal absorbers testing indicated absorber efficiency was_ in excess of the assumptions used for FSAR Update. determination-of site boundary dose.

It may therefore be stated that the radiological consequences _of a load ' drop accident during this event would have been-conservatively. bounded by the FSAR expected case fuel handling accident'.

During this event, each time a door was opened.an operator was_present while the door was open. Operators recognize that FHB doors must be maintained closed if a radiation alarm occurs for the FHBVS. If an accident had occurred, the FHB radiation detector would have detected'any significant iodine activity and alarmed, alerting operators to close any open FHB doors.

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The FHB exhaust air flow would have automatically shifted to the iodine ramoval mode (although during this event the FHB ventilation system was already in the iodine removal mode), and any iodine activity would have exhausted through the charcoal filters.

Therefore, the health and safety of the public were not adversely affected-by this event.

V. Corrective Actions A. Immediate Corrective Actions:

1. The leaking ammonia /hydrazine valve was isolated. 4

2. All fuel handling activities were suspended and the fuel handling equipment was placed in a safe configuration when FHB pressure was identified as out-of-specification.

3. FHB pressure was verified to be more negative than negative.

l 1/8-inch (0.125") H,0 prior to the resumption of the insert-shuffle.

4. An event summary was prepared and personnel were briefed'on this event and the necessity for awareness-of TS requirements during response to an incident.

B. Corrective Actions to Prevent Recurrence:

PG&E will enhance plant response procedures to clarify that- the SFM should be notified prior to keeping a ventilation boundary door open for more than personnel egress.

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DIABLO CANYON UNIT 2 0l5l0l0l0l3l2l3 93 -

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t VI. Additional Information A. Failed Components:

None. I B. Previous Similar Events:

LER 2-90-002, " Fuel Handling Building Ventilation System Inoperable During Fuel Movement Due to Programmatic Error" The corrective actions to prevent recurrence from this 1990 event 4 included the installation of. signs at FHB doors to remind personnel i that the doors were pressure boundaries for the FHB ventilation system. This corr ctive action wa effective, sinca each time the ,

door was. opened during the event of March'17, 1993, an. operator was-present so that the doors could be closed in the event.of:a radiation  ;

alarm in the FHB. The fact that these doors'were ventilation  ;

boundaries was identified, but it was not common knowledge to all  !

plant personnel that blocking open the doors could result in exceeding.-

the FHB negative pressure limits.

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