ML20151H568

Safety Insp Repts 50-456/88-13 & 50-457/88-11 on 880314-25. Violation Noted.Major Areas Inspected:Events Surrounding Inoperability of Nonaccessible Area Exhaust Filter Plenums

ML20151H568
Person / Time
Site:	Braidwood
Issue date:	04/14/1988
From:	Hinds J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
To:
Shared Package
ML20151H543	List: IR 05000456/1988011 ML20151H554 ML20151H568
References
50-456-88-13, 50-457-88-11, NUDOCS 8804200429
Download: ML20151H568 (6)

See also: IR 05000456/1988013

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U.S. NUCLEAR REGULATORY COMMISSION

REGION III

Report Nos. 50-456/88013(DRP);50-457/88011(ORP)

Docket Nos. 50-456; 50-457 License Nos.'NPF-72; NPF-75

Licensee: Connonwealth Edison Company

Post Office Box 767

Chicago, IL 60690

Facility Name: Braidwood Station, Units 1 and 2

Inspection At: Braidwood Site, Braidwood, Illinois

Inspection Conducted: March 14 through March 25, 1988

Inspectors: T. E.-Taylor

T. M. Tongue

Approved B :

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tor Projects Section 1A Date

Inspection Sur. mary

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3_nspection from March

0-456/88011(DRP); 14 through March 25, 1988 (Report Nos.

50-457/88011(DRP))

Areas Inspected: Special safety inspection conducted by resident inspectors

to evaTuate circumstances and significance of events surrounding the

inoperability of non-accessible area exhaust filter plenums on December 18,

i 1987, and on Harch 13, 1988, for Units 1 and 2.

Results: One violation cf NRC requirements was identified: two events

involving two inoperable non-accessible area exhaust filter plenums with

the subsequent failure to place units in the applicable operating modes as

specified in Technical Specification 3.0.3.

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DETAILS

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1. Persons Contacted

Commonwealth Edison Company (CECO)

• R. E. Querio, Station Manager

K. Kofron, Production Superintendent

D. E. O'Brien, Administrative Superintendent

• G. Masters, Operations Assistant Superintendent

• P. Barnes, Regulatory Assurance Supervisor

• T. Simpk'in, Regulatory Assurance

• P. Holland, Regulatory Assurance

J. Kuchenbecker, Shift Control Room Engineer

M. Hess, Nuclear Station Operator

M. Parks, Equipment Attendant

• Denotes those attending the exit interview conducted on March 25, 1988.

2. Purpose

This inspection was conducted to review the circumstances surrounding the

inoperability of two non-accessible area exhaust filter plenums. On two

occasions (December 18, 1987, and March 13,1988), while implementing

equipment out-of-services (00Ss), the licensee rendered two redundant,

independent filter plenum trains inoperable.

3. Description of the Event

The first instance (on December 18,1987) of non-accessible area

exhaust filter plenum inoperability occurred at about 9:13 a.m. when

train C was taken out-of-service for a charcoal sample surveillance.

Prior to this action, th.e train B inlet damper was closed as part of

the system's nomal lineup. A closed train B inlet damper prevents

starting the charcoal booster fans for train B. Some of the operations

personnel were not aware that having an inlet damper on one train closed

and taking another train out of service was contrary to Technical

Specification (TS) 3.7.7 requirements. Therefore, at 9:13 a.m. , when

train C was taken out of service, two trains of the non-accessible area

exhaust filter plenums were inoperable. At 11:30 p.m. , the error was

identified by operations personnel, and the B inlet damper was immediately

opened. Technical Specification 3.7.7 allows only one train inoperable

for up to seven days. The error was not discovered for about 15 hours1.736111e-4 days <br />0.00417 hours <br />2.480159e-5 weeks <br />5.7075e-6 months <br />,

during which time two shift turnovers occurred. The unit common panel,

which includes inlet damper position indication, is walked down by the

oncoming shift as part of the shift turnover, but the plenum configuration

was not identified as an abnormal system lineup.

The second event began on March 13, 1988, at about 2:00 a.m., when sevan

00S's for control relays required for an environmental qualification

inspection were being implemented. The 00Ss required removal of c(ntrol

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fuses for the fuel building and accessible auxiliary building ventilation

system relays. The nuclear station operators (NS0s) who determined the

00S boundaries were not aware that removal of these fuses would

de-energize control power for the charcoal booster fan outlet dampers

and thus would render two non-accessible area exhaust filter plenums

inoperable. The 00Ss were intended to remove control power only from

the fuel handling building and accessible auxiliary building ventilation

systems. At about 8:30 a.m., the center desk NS0 noticed that the

position indication lights for the inlet and outlet dampers for all three

trains of the non-accessible area exhaust filter plenum ventilation

system were not illuminated. The licensee conducted an investigation,

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and the initial assessment indicated that all three trains were inoperable.

l At 9:00 a.m., TS 3.0.3 was entered. At 9:45 a.m. on March 13, 1988, a

l temporary lift was initiated to restore the control power fuses. When

I the fuses were installed, the plenums were declared operable, and TS 3.0.3

was exited. A subsequent investigation by the licensee at about 10:00

a.m. identifisd that train C had been operable for the duration of the

event. The inspectors' discussion with the involved NS0s identified that

the NS0s were not aware, prior to the event, that removal of the identi-

fied fuses would affect the operation of the non-accessible area

ventilation system. In accordance with a comitment made in response to

the operational readiness inspection, two NS0s are required to determine

the 00S boundaries. Non-accessible area exhaust filter plenums A and B

were inoperable for about seven hours. The non-illumination of the inlet

and outlet damper position indication, which prompted the licensee's

investigation at 8:30 a.m., was not identified at the time the 00Ss

were hung (2:00 a.m.), nor at the shift turnover when the shift engineer,

shift control room engineer, and center desk NSO walked down the panels

sometime between 6:00 and 7:00 a.m.

These events of December 18, 1987, and March 13, 1988, are collectively

considered to De a violation of Technical Specification 3.0.3

(456/87011-01(DRP);457/87013-01(DRP)).

4. Chronology of Events,

a. 12-18-87 At about 9:00 a.m., Unit I was in Mode 1 with the non-

accessible area filter plenum exhaust (NAFPE) system

I in a nonnal operating lineup with the train A and

train C inlet dampers open and the train B inlet damper

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closed.

12-18-87 At about 9:13 a.m., an out-of-service was implemented on

train C for charcoal sample analysis while the train B

inlet damrer remained closed. This exceeds the action

statement of TS 3.7.7.

12-18-87 By 4:13 p.m., two trains of the NAFPE system had been

inoperable for about seven hours, and the licensee had

not reduced power to reach Mode 3 (Hot Standby). This

is contrary to TS 3.0.3.

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12-18-87 By 10:13 p.m., two trains of the NAFPE system were still

inoperable, and licensee had not reduced Unit 1 to

Mode 4. This is also contrary to TS 3.0.3.

12-18-87 At 11:30 p.m., the licensee identified that the train B

inlet damper was closed with train C inoperable for

surveillance activity. The licensee immediately opened

the B inlet damper to restore Train B to operable status,

b. 3-13-88 At 2:00 a.m., the licensee implemented several out-of-

services for control power fuse removal on the fuel

handling and accessible auxiliary building ventilation

systems. This action resulted.in lost position indication

for the inlet and outlet dampers. The fuse removal also

de-energized control power to the charcoal booster fan

outlet dampers for trains A and B of the NAFPE system,

thereby rendering two trains inoperable. This is contrary

to TS 3.7.7.

3-13-88 'At 8:30 a.m., the Center Desk NS0 noticed that the

position indication for all inlet and outlet dampers for

the NAFPE system were not illuminated. The licensee

initiated an investigation of system status.

3-13-88 By 9:00 a.m., two trains of the NAFPE system had been

inoperable for seven huurs, and action had not been taken

to reduce Unit 2 to Mode 4. This is contrary to TS 3.0.3.

3-13-88 At 9:00 a.m., the licensee entered TS 3.0.3, believing

that all trains of the NAFPE system were Inaperable.

3-13-88 At 9:45 a.m., the licensee implemented temporary lifts, to

re-install the control. power fuses. With the NAFPE system

operable, the licensee exited TS 3.0.3.

3-13-88 At 10:00 a.m., the licensee discovered that train C of

the NAFPE system had been operable for the entire time

of the event.

5. Evaltation of the Event

ihe NAFPE system (two trains required) is manually started during a high

radiation condition in the auxiliary building or automatically from a

safety injection signal (hi containment pressure, lo pressurizer

. pressure, low steamline pressure, and manual initiation) from either

unit. The inoperable conditions from 2:00 a.m. to 9:45 a.m. on March 13,

1988 and from 9:13 a.m. to 11:30 p.m. on December 18, 1987, reduced

the exhaust ventilation capacity of the system to 50%. Two of the

system's intended functions are to minimize the release of airborne

radioactivity during a high radiation condition in the auxiliary building

and to maintain environmental conditions in engineered safety feature

areas and cubicles.

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During the operational readiness inspection, the NRC identified a

concern that the 00S boundaries had not been adequately defined on

other occasions. In response to this concern, the licensee committeu

to having two NS0s determine the 00S boundaries for the March 13, 1988

00S. Two NS0s were involved; however, the technical requirements.were

beyond their capabilities.

The significance.of these events is that on two separate occasions the

licensee initiated actions which rendered two trains of the NAFPE system

inoperable and was not aware of the inoperable condition. On both

occasions the licensee exceeded the action statement for TS 3.7.7 and

was in apparent violation of TS 3.0.3. The plant status at the time of

these events, however, considerably reduces their safety significance, >

as a result of the low source term of each unit.

At the time of the December 18, 1987 (9:13 a.m. to 11:30 p.m.) event,

Unit I (U-1) was at 88% power. Unit 2 (U-2) was preparing for initial

fuel load. During the March 13, 1988 event (2:00 a.m. to 9:45 a.m.),

U-1wasinMode4(HotShutdown)withreactorgoolantsystem(RCS)

pressure at 375 psi and RCS temperature at 340 F. U-2 was in Mode 3

(Hot Standby) at normal ogerating pressure and temperature (pressure

2235 psi, temperature 557 F). U-2 had attained initial criticality on

March 8, 1988, and was conducting low power physics testing.

6. Corrective Action Initiated by the Licensee

a. For the December 18, 1987 event, the licensee, upon reali::ing the

incorrect system conf 1c! ration, imediately opened the closed train

B inlet damper. LERs 87-063-00 and 87-063-01 were issued to address

this event; the stated corrective actions include: (1) training of

Station Control Room Engineers with regard to the basis for the

supplementary guidance relative to the subject Technical Specifica-

tion and a review of similar events experienced at Byron Station;

and (2) inclusion of this event in the Licensed Operator Requalifi-

cation Program. Also, a Technical Specification Interpretation was

issued to clarify what constitutes an operable filter plenum train,

b. For the March 13, 1988 event, the licensee's immediate action was to

initiate a temporary lift to restore power to the charcoal booster

fan outlet dampers to restore NAFPE system operability. This event

will be addressed in the forthcoming LER 88-006. Th.'s evcnt will

also be addressed by the licensee's Potentially Significant Event

(PSE) program, which identifies corrective actions and recommenda-

tions. For this event, the identified corrective actions are:

(1) that the event will be brought to the attention of all licensed

personnel, with en'phasis on close review of uncommon multiple i

identical'00Ss with electrical isolation points to ensure that '

license requirements are not downgraded; and (2) that upon review

of the final report, statior management will initiate or modify

proposed corrective action.

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7. Conclusion

These events indicate a weakness in the licensee's implementation of the

OSS process and Technical Specification application. The root cause of

the December 18, 1987 event was an operator taking a system train out

of service without proper knowledge of the required system configuration.

The March 13, 1988 event occurred because the NS0s determining 005

boundaries for the relay removal were not knowledgeable of the overall

effect of-pulling the selected control power fuses. Both events resulted

in rendering two trains of the NAFPE system inoperable for several hours.

During the time the two NAFPE system trains were it,aperable, one operable

non-accessible area plenum was available to provide 50% system capacity.

The licerisee provided the staff with an analysis which demonstrates that

offsite doses and doses to control room personnel would have been

maintained within the limits of 10 CFR 100 and 10 CFR 50, Appendix A,

Criterion 19, with a ccmplete loss of non-accessible area ventilation

considering the small emergency core cooling system leakage and the low

RCS coolant source term that existed at the time of the event.

The licensee should re-evaluate its corrective actions associated with

the operational readiness inspection concerns and identified in LERs

87-063-00 and 87-063-01. The individuals determining the boundaries

should be technically proficient in the 00S equipment affected.

Management should also ensure that prior to taking a system out of

service ar.d after implementing an 00S, a determination, relative to

present plant status, should be made to ensure that repetition of this

type of event dres not occur. ,

The NRC recognizes that the root causes for these events are similar

although different in origin; however, the overall effect on

safety-related system operability is considered unacceptable. The NRC

is concerned that these events are indicative of ir. adequate performance

by licensee management in ensuring the operability of safety-related

systems.

8. Exit Interview (30703)

The inspector met with the licensee representatives denoted in

Paragraph 1 at the conclusion of the inspection on March 25, 1988.

The inspector summarized the scope and results of the inspection and

discussed the likely content of this inspection report. The licensee

acknowledged the information and did not indicate that any of the

information disclosed during the inspection could be considered

proprietary in nature.

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