ML20059M884

Intervenor Exhibit I-MFP-39,consisting of Re LER 1-89-019-01

ML20059M884
Person / Time
Site:	Diablo Canyon
Issue date:	08/18/1993
From:	Shiffer J PACIFIC GAS & ELECTRIC CO.
To:
References
OLA-2-I-MFP-039, OLA-2-I-MFP-39, NUDOCS 9311190418
Download: ML20059M884 (7)

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acific Gas and Electric Company EM..-.n93  %.T.

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September 19, 1991 ,

g-PG&E Letter No. DCL-91-226 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555 Re: Docket No. 50-275, OL-DPR-80 Diablo Canyon Unit 1 Licensee Event Report 1-89-019-01 Fuel Handling Building Ventilation System Inoperable During fuel Movement Due to Building Seal Degradation Gentlemen: ,

Pursuant to l' CFR 50.73(a)(2)(1)(B), PG&E is submitting the enclosed revised LPMNesums:Grea M eyert (LER) concerning the in 6 Lt4e F"r --*--JmAding (FHBi ventilIttintstem.Auring;fuehmoirement, in j violation of Techn E l; Specification 3.9.12.b. The.cause of the event '

is degradation of the FHB seals.

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

l l Sincerely, ,

l

). D. Shif gr .

cc: Ann P. Hodgdon John B. Martin , , , , , .

Phillip J. Morrill 1 Paul P. Narbut tiuctEAR etGUtATORY COMMISSION

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Diablo Distribution e ew meter er MM/r/c GMS mrd MND l INP0 n,n . _ immo f _

DC1-91-TN-N007 ^kic 'u r ".;'r / . - R:nc1ED _

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i UCENSEE EVENT REPORT (LER) 165622 o' j ractury suma (3) mee rrt inaars tan past ta-DIABLO CANYON UNIT 1 0 5 0 0 0l2l7l5 1 61 vnu m FUEL HANDLING BUILDING VENTILATION SYSTEM INOPERABLE DURING FUEL MOVEMENT DUE TO i UNKNOWN CAUSE i

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itLEptsa f GaSSEO MARTIN T. HUG, SENIOR REGULATORY COMPLIANCE ENGINEER """ *"*

805 545-4005 omanuve se uur Den saca coomane pasums antareas in vises asseur taan CAUSE Sv5f ts. Cappe.tui seassur . 80s at E CaWSE SYSTOs CWo0Mt.r1 senpe# .. 80s LS I III III I l' I I I I-1 I I1I III asseussuvat assest saaseva 04)

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MCTED asMitsl0N I l YEs (if yes, semp(ete EXPECTED menisticu 30 DATE Os) l l 05' ;M h .

ass,anCt os:

On January 1, 1991, at 1700 PST, with" Unit 1 in Mode 1 at 100 percent power, the Fuel Handling Building (FHB) ventilation system was declared inoperable' after i failing to meet the negative 1/8-inch water gauge-pressure requirements specified i in Surveillance Test Procedure (STP) M-41, " Fuel . Handling Building Ventilation

~

System - udP and Halide Penetration." Sinea the last successful performance of STP M-41, fuel ~and heavy loads were ~ moved over the spent ;feal ~ pool. No work '

performed subsequent to the completion of the last successful'STP M on . .

September 18, 1989, that could have resulted in test failure has been identified.

Therefore, it is conservatively assumed that the FHB ventilation system has been

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inoperable since the last perforiaance of STP M-41, on September 18,'1989. Fuel movement and receipt have occurred since the last successful perforisance of STP M- i 41, including fuel movement during the Unit.I third refueling outage on October. l 15, 1989. Therefore, it is conservatively assumed that a potential violation of  ;

Technical Specification (TS) 3.9.12.b. occurred on October 15,'1989. l To bring the pressure within the acceptance criteria, leaks have been_ sealed, I exhaust fan ducts have been cleaned, and the supply flow to the FH8 has been - l temporarily reduced. The cause of the inoperable <FHB ventilation system is under  ;

investigation. - The results of the investigation, as well as appropriate H corrective actions, will be included in a supplemental LER.

52195/0085K .

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UCENSEE EVENT REPORT (LER) TEXT CONTINUATION 165622l ,

,cc m re wis m ooc u t w eca m tra ==ca m nu m vana sawumas .

amse L .

l DIABLO CANYON UNIT l- 0l5l0l0l0l2l7l5 91 -

0l012 -

0l0 2l*'l6- l tcat g m I. Plant Conditions I Unit I was in Mode 1 (Power Operation) at 100 percent power.

! II. Descrintion of Event i

)

e A. Event:

j On January 18, 1991, the Unit 1 Fuel Handling Building (ND) (FHB)-

! -failed to meet the negative 1/8-inch water gauge (WG) pressure acceptance criteria of Surveillance Test Procedure (STP) M-41, " Fuel

! Handling Building Ventilation System - 00P. and Halide Penetration."

i The FHB pressure for the test was negative 1/16-inch WG.-- STP M-41 was last successfully performed on September 18, 1989. The STP M-41 i performed on January 18, 1991, was the scheduled 18-month

[ surveillance. Although-portions of STP.M-41 were performed prior to -

i the movement of new fuel for the Unit I fourth refueling. outage, the pressure verification portion of the test was not performed until after fuel receipt due to the placement of the pressure test'.in the procedure-sequence.

The FHB ventilation system (VG) was declared inoperable at 1700 PST on.

January 18, 1991. Fuel movement and activity .over the spent fuel pool were suspended in accordance with the limiting condition for operation l (LCO) for Technical Specification (TS) 3.9.12.b.

Investigations were conducted and concluded that no changes were made which have impacted the FHB ventilation system subsequent to the-perfomance of the last successful STP M-41 on September 18, 1989.

Based on a conservative evaluation of the'results of the-investigation, it appears that the factors which caused the failure of.

, the test were most likely present during fuel movement. Therefore,.

the FHB ventilation system is conservatively considered to have been inoperable since the last performance of STP.M-41. Fuel receipt and-

movement have occurred since the last:successfu1~ performance of STP M-41, including. fuel mo'vement during the Unit I third refueling.

outage-(IR3) on October 15. 1989. Therefore, it is conservatively

! assumed that a potential violation of TS 3.9.12.b.' occurred on October

} 15, 1989.

i '

l On February 5,.1991, after reaching Mode 5-(Cold Shut'down) during-the.

Unit 1 fourth refueling outage, the supply fans for the FH8 were shut-l off. The FHB pressure decreased to approximately negative 0.6 inches.-

l WG. Administrative controls.were placed on the fans to prevent them i from being turned back on during fuel movement.

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52195/0085K i

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UCENSEE EVENT REPORT (LER) TEXT CONTINUATION 165622,[l FOCILIVY seest (1) DOCLET essG(a (2) L:a ansets s) PA6s (3) -

W =

f(11 (47)

DIABLO CANYON UNIT 1 0l5l0l0l0l2l7I5 91 -

0l0l2 -

0l0 3 l"l 6 B. Inoperable Structures, Components, or Systems that Contributed to the Event:

None.

C. Lates and Approximate Times for Major occurrences:

1. October 15~, 1989, at 1850 PDT: Event dates- Fuel moved during;1R3.

2. January 18, 1991, at 1700.PST: Discovery date _FHB ventilation system declared inoperable. LCO for TS

.3.9.12 entered.

Other Systems or Secondary Functions Affected:

D. --

None.

E. Method of Discovery:

Utility personnel discovered the problem .during the performance of a -

scheduled STP. ,

F. Operators Actions:

The FHB ventilation system was declared inoperable. .

G. Safety System Responses:

{

None required.

III. Cause of the Event An investigation of the causes for failure of the FHB to meet the acceptance

' criterion of STP M-41.is being conducted. The investigation is evaluating +

j the following potential causes:

i j 1. Unacceptable leakage into the FH8

2. Improper balance' between supply and exhaust- flows j The FHB has been inspected to identify potential leaks or reasons for the increased pressure. The investigation did not identify any doors that were-open during the STP, or any missing siding. .However, several problems were

identified

L I. Saps.between sections of sheet metal siding

2. Unsealed piping penetrations 4

3. . Missing or degraded door and piping seals 52195/0085K 7

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gu LICENSEE EVENT REPORT (LER) TEXT CONTINUATION 165622 i ooust assega (a) Las same .si nog (s) uctutt sewer (a) i

! DIABLO CANYON UNIT 1 0l5l0l0l0l2l7l5 91 -

0l0l2 -

0l0 4 l"l 6 TEAT (17) i i .

-4. Saps between the FHB movable crane wall and the FHB fixed walls l Through wall oxidation of FHB sheet metal siding i S.

4 6. Reduced flow through the FH8 exhaust fans

! 7. Equipment obstructing an exhaust duct in the new fuel storage rooms l Dirt was cleaned from the exhaust ducts to increase exhaust flow from the

! building, and leaks were sealed. STP M-41 was-then re-performed. The i pressure still did not meet the acceptance criterion; however, the pressure J

! had improved relative to the acceptance criterion.

! Further investigative actions are being conducted.- The revious STP M-41 i data is being re-reviewed to determine if _the imbalance. tween the supply j and exhaust flows identified during the performance of STP M-41 on January I

18, 1991, are consistent with past successful performances. Also,

! meteorologica' data from past performances of STP M-41 are being reviewed to j evaluate the effects of varying wind conditions, if any, on the results of .

l STP M-41. Additional leaks.are being investigated and sealed.

The conclusions from the investigation will be reported in a supplemental LER.

t l IV. Analysis of the Event 'i l A. Safety Analysis: 1 l In order to assure that all potentid releases from the spent fuel a pool are exhausted through the FH8 exhaust filters, the fuel pool area must be maintained at a negative pressure. The TS bases for the FHB ,

i ventilation system states, "The limitations on the FHB ven'"ation system ensure that all-radioactive material

• released fros' an ' -

! irradiated fuel assembly will be filtered through the HEPA filters and ,

charcoal adsorber prior to discharge to the atmosphere. The~

< operability of this system and the resulting iodine removal capacity  !

are consistent with the assumptions of the: safety analysis." i I Final Safety Analysis Report (FSAR) Update Section 9.4.4.1 goes on to .

say "...The requirements for the system design are as fo11ows:...(3) l

- Remove more air than is supplied so that all potential air leakages will be inward..." The FSAR accident: analysis assumes-that the fuel j pool area at the 140 foot elevation is at a negative pressure with

~

respect to the ambient, which will assure that near the area of the spent fuel handling accident there would be infiltration of air from the ambient rather than exfiltration which could by-pass the FHB exhaust filters, in accordance with the TS bases, i The FH8 ventilation system was able to maintain a negative pressure in the spent at fuel pool area between 0.05 inches and 0.09 inches'WG.

The differential pressure for Unit 1 is measured in the northeast 4

corner of the FHB at the same elevation as the surface of.the spent 52195/0085K m.-,w , u-, .- cei. .,__-,sm---_ . mm,, ,,,.,--.......e,.m .,,.u.u %e. . . . ,,enn,.w.. ,4,w,ws..,vw % . w +,e ie,o-, A=>b,.e.gy,. wma 's

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i UCENSEE EVENT REPORT (LER) TEXT CDNTINUATION 165622 .

l' i exams - m osem a m m y 'e> == m DIABLO CANYON UNIT 1 0l5l0l0l0l217l5 91 -

0l0l2 -

0l0 5 ll 6 l sw on fuel pool. The pathway between the instrument and the pool'is unobstructed. The low pressure leg of the_ instrument is located in ,

i the northeast corner of the building at the.same elevation as-the I l

surface of the spent fuel pool. The-high pressure leg of the instrument is located outside the northeast corner of the FHB, and is I shielded from wind effects ~-  ;

The FHB ventilation system creates a sweeping effect across the surface of the pool. The ventilation path is also unobstructed. As a result, the effect of stagnant air pockets is minimized. Considering the ventilation path and the. location of the measuring instruments,  ;

the measured pressure is indicative of the pressure at the surface of the spent fuel pool.

Although the negative pressure requirement of the TS was not met,  :

sufficient negative pressure was maintained to prevent gross: air ,

exfiltration from the spent fuel pool area. This conclusion is based on a qualitative evaluation performed for an analogous Unit 2 event i described in LER 2-90-002. Therefore, since the FHB spent fuel pool area was maintained at a negative pressure, the assumptions in the FSAR Update regarding a postulated fuel handling accident are -

maintained, and the health and safety of. the public were not affected by this event.

V. Corrective Actions I A. Immediate Corrective Actions:

1. The FHB ventilation system ms declared inoperable, and fuel -!

movement suspended. l

2. The exhaust fan ducts were cleaned. j i

3. Identified gaps in.the FHB pressure boundary were sealed. >

4. The FHB supply fans were shut off and administrative 1y controlled after reaching Mode 5. This. decreased the FHB pressure to approximately negative 5/8-inch WG. ,

5. As an_ interim measure, a recurring' task.was created to measure ,

the pressure of the FH8 every 7 days during fuel movement.or when loads are moved,over the spent fuel pool to assure that the .

negative pressure requirement for the FHB is satisfied. l l

B. Corrective Actions to Prevent Recurrence:  :

Corrective actions to prevent recurrence will be determined after the conclusion of the investigation, and reported in a supplemental LER '

52195/0085K

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UCENSEE EVENT REPORT (LER) TEXT CONTINUATION 165622

' m,, - n> -..,-.m

u. ., ... o, DIABLO CANYON UNIT I 0l5l0l0l0l2l7l5 91 -

0l0l2 -

0l0 6l"l6

,131 07)

VI. Additional Information A. Failed Components:  ;

None.

B. Previous LERs: .

LER 2-90-002-01 FHB Ventilation System Inoperable During ,

Fuel Movement Due to Personnel Error.

The Unit 2 FHB ventilation system was made inoperable when equipment ~

used in support of the third refueling outage was routed through .

several FHB doors. The root cause was determined to be personnel error in that an engineer failed to recognize personnel doors as part of the FHB ventilation boundary. The corrective actions' included placing signs on doors to inform personnel of the. ventilation ~

boundary, and requiring personnel to inform the shift supervisor prior.

to blocking doors in an open position. Since doors were not blocked open during the recent event, the corrective action to prevent recurrence would not have prevented this event.

l 52195/0085K

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