Text

Insp Rept 50-456/88-07 on 880301-17.Apparent Violation Noted:Failure to Have Control Room Ventilation Sys Operable. Appropriate Enforcement Action Will Be Determined.Major Areas Inspected:Licensee Actions Following Startup Test
	ML20150E992
Person / Time
Site:	Braidwood
Issue date:	03/25/1988
From:	Gill C, Greger L; NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
To:	;
Shared Package
ML20150E984	List: ML20150E981; ML20150E992;
References
	50-456-88-07, 50-456-88-7, NUDOCS 8804040227
	Download: ML20150E992 (16)
	v • d • e

'

, , , . '.*, ,

. .

U.S. NUCLEAR REGULATORY C0t941SSION

REGION III

5 Reports No. 50-456/88007(DRSS)

Docket No. 50-456 License No. NPF-70

Licensee: Commonwealth Edison Company

Post Office Box 767

-Chicago, IL 60690

Facility Name: braidwood Station, Unit 1

Inspection At: Braidwood Site, Braidwood, Illinois

Inspection Conducted: March 1-17. 1988

4

h.

i Inspector: Charles F. Gill 3MIf

Date '

Approved By: L. R g r, e O

Facilities Radiation Protection Date

Section

Inspection Summary

l Inspection during the period March 1-17, 1988 (Report No. 50-456/88007(DRSS))

'

Areas Inspected: Special, announced inspection of licensee action following

a startup test which indicated operability problems with the Control Room

Ventilation Systems.

Results: The licensee's failure to have Control Room Ventilation Systems

operable apparently violated regulatory requirements (Section 4). The

l appropriate enforcecent action for this failure will be determined and

f communicated to the licensee by separate correspondence.

8804040227 880325 0

PDR ADOCK 05000456

. -_

O _ - - . .-

DCD _ _ ._ , _ , , - . _ _ _ ._ - .

.,.,. - '.',

,

. .

'

DETAILS

. 1. Persons Contacted

B. Andrews, Shielding Project Engineer, S&L

- P. Barnes, Regulatory Assurance Supervisor

E. Carroll, Regulatory Assurance Engineer

D. Christinia, Project Field Engineer

L. Davis, Assistant Superintendent Technical Services

D. Elras PWR Engineering Superintendent

D. Galants, Senior Electrical Project Engineer, S&L

P. Holland, Regulatory Assurance Eraineer

S. Hunsader, Nuclear Licensing Administrator

J. Jasnosz, AR/PR Coordinator

G. Lahti, Assistant NSLD Head, S&L

F. Lentine, PWR Nuclear Licensing Supervisor

M. Lohmann, Project Startup Construction Superintendent

i #C. Moerke, Project Engineer

#P. Myrda, Project Field Engineer

- D. O'Brien, Services Superintendent

W. Paschal, Assistant HVACD Head, S&L

J. Phelan, Lead Electrical Engineer

- R. Richard, HVAC Group Leader

.

8, Sheldon, PWR Engineering Manager

!

- T. Simpkin, Regulatory Assurance Engineer

S. Stimac, Staff Engineer

L. Greger, NRC/RIII, Chief, Facilities Radiation Protection Section

J. Hinds, NRC/RIII, Chief, Reactor Projects Section 1A

T. Tongue, NRC/RIII, Senior Resident Inspector

The inspector also contacted other licensee and contractor employees.

Denotes those attending the interim exit meeting on March 4, 1988.

Denotes those attending the telephone exit meeting on March 17, 1988.

2. General

This inspection which began on March 1, 1988, was conducted to review the

circumstances surrounding a startup test which indicated inoperability of

a Control Room Ventilation System while the plant was in operational

Mode 1 (power operation).

3. Licensee Event Report (LER) Followup

Through direct observations, discussions with licensee personnel, and

review of records, the following event report was reviewed to determine

2

-.- _

.

.

. :..

. .

that reportability requirements were fulfilled, immediate corrective

action was accomplished, and corrective action to preve.it recurrence had '

been accomplished in accordance with Technical Specifications. ;

i

LER No. Description 1

456/87-058-00 Both Trains of Control Room Ventilation

Inoperable Due to Incorrect Design f

Incorporation

The LER was reviewed as part of the inspection into the apparent inability .

of both independent Control Room Ventilation Systems to meet their design !

requirements; this matter is discussed in Section 4.

4. Inability of Independent Centrol Room Ventilation Systems to Perform

Their Design Requirements

a. Event Summary

On November 6, 1987, during a review of the Control Room Ventilation

Startup Test (BwSV VC-30) and Engineering Design Change DC-V041 by

the licensee's Project Engineering Department (PED), it was

identified that the train B heater for the emergency makeup filter

unit did not energize during the startup test on October 2, 1987,

although the fan was operating. After consulting with station

technical staff engineers and the Architect Engineer (Sargent &

Lundy), PED confirmed that an error in design existed in the heater

interlock logic circuitry and the heaters on both trains (A and B) :

of the Control Room Ventilation (VC) Systems would not energize at !

the proper time. ;

At 1135 on November 6, 1987, both trains of VC were declared f

inoperable and Technical Specification 3.0.3 was entered. Upon

declaring both trains of VC inoperable, the station's Electrical

Maintenance Department was contacted to determine if the train B

heater would energize with the emergency fan operating. The test

t of the train B heater revealed that the heater was energized as r

j soon as the fan was started but de-energized shortly afterwards.

After installation of temporary alterations on both trains of VC i

j to correct the design error (miswiring), the train B heater was

'

again tested; the heater was found to energize shortly after the i

emergency tan began operation and to remain energized. Based on

, the success of the test of the train 8 heater, Technical

i Specification 3.0.3 was exited at 1234. Since a test was not made

at the time for correct operation of the train A heater, LC0 Action p

Requirement 1.a of T/S 3.7.6 was entere' on train A of the Control ;

Room Ventilation Systems. -

i

e

r

!

3 [

.nw-----,-m- ,.-,-.r, ,-,--,--,,--,-m--

. . - - - _ - _- _ - - . .-- . _ - .- . - - . -. .. -

. .

'

..- ..

.

. .

1

Upon reviewing setpoint data sheets for the f an dP heat ar interlock

logic switch for the Control Room Ventilation Systems, station i

technical staff engineers noted on November 6, 1987, that the setpoints ,

had not been reset, as required, after design change. On November 7,

t 1987, the as-found setpoint on train A wan 16.5" wg; af ter setpoint ,

readjustment the value was 5.75" wg, compared to the desired setpoint ,

of 5.73" wg. The LC0 action requirement on train A was exited at ,

08?0 on November 9, 1987. Because train B was demonstrated operable

with the existing fan dP heater interlock switch setpoint on ,

November 6, 1987, LCO Action Requirement 1.a of T/S 3.7.6 was not

entered for setpoint readhstment until 0858 on November 20, 1987. l

. The as-found setpoint was 13.2" wg; the as-left setpoint was 5.70" wg "

1 on November 20, 1987, compared to the desired setpoint of 5.73" wg.

The LC0 action requirement on train B was exited at 1312 on ,

, November 21, 1987. The probable effect that the switch wiri q and

setpoint errors had on system operability are discussed further in

Subsection 4.g.

! Refer to Appendix A for the sequence of relevant events.

b. Event Causation i

The following occurrences contributed to tne failure of the Control

j Room Ventilation Systems to meet their design requirements:

(1) The incorrect heater operation was the result of a design error

in the Architect Engineer's (A/E's) electrical schematic and ,

wiring diagrams issued via Engineering Change Notice (ECN)

l No. 34446 on December 16, 1986.

(2, The cause of the design error was an incorrect interpretation

by the A/E's Electrical Project Engineering Division of the

l "Normal / Abnormal" nomenclature shown on the Mechanical-Control

3

and Instrumentation Logic Diagram (issued via ECN No. 34272 on

December 16, 1986) to describe the interlock function.

i (3) Adequate measures were not established for coordination among

i participating design organizations in that ECN No. 34272

l generated by the A/E's Control and Instrumentation Division was

improperly understood and incorrectly incorporated into ECN

l No. 34446 by the A/E's Electrical Project Fngineering Division.

l (4) Adequate measures were not provided for verifying or checking

! the adequacy of design in that a design review was not

l adequately performed to assure that the design change initiated

! by ECN No. 34446 was proper before the design change was

j complete.

!

.

4

l

!

l

L

v

: .. :..

-

,

(5) Failure to detect these design errors in the heater control

circuits at the time of installation was due to a preservice

testing deficiency in that the design change was not verified

by component demonstration or retest, although a functional

check of heater operation was performed.

(6) Contrary to standard preoperational testing practice, setpoint

checks of the heater interlock logic switches were not made

upon installation. The licensee's Instrument Maintenance

Department (IMD) apparently was not aware of the need to

adjust the setpoints after completion of ECNs Nos. 34272 and

34446. Due to the setooint changes not being made, heater

operation under certain conditions could appear normal, as it

did during the functional test and subsequent surveillances

(see Appendix A).

(7) When the startup test revealed that the heater was not operating

on train B, test personnel apparently did not realize that heater

operability is directly tied by the Technical Specifications to

Control Room Ventilation System operability.

Refer to Appendix A for the sequence of relevant events.

c. Corrective Actions

(1) Initial actions were taken to correct the wiring and setpoint

errors when they were discovered. A modification package for

permanent alterations to the heater interlock logic circuits

of both trains of the Control Room Ventilation System is being

developed.

(2) The A/E's engineering and quality assurance pertunnel are

investigating the design error to verify that it is an isolated

error and to determine the appropriate corrective action to

prevent recurrence.

(3) The licensee has identified no other preservict t? sting

deficiencies involving a design change. The licensee therefore

considers this incident to be an isolated event and proposes no

other corrective actions regarding the preservice program,

d. Safety Significance

(1) The operability of both trains of VC was jeopardized by the

incorrect design changes and failure to properly adjust the

heater interlock logic switch setpoints from the time of

system required operability at 2120 on May 29, 1987 (initial

critical .ty), until 1342 on November 21, 1987, after both

trains had the design errors and setpoints corrected. The

5

, .

'

.

.- ...

. .

design error would result in heater operation whenever the fan

was energized unless the high dP setpoint was reached. Had the

correct setpoint changes been made initially, the fan dP setpoints

would have been reached on both trains shortly after fan

energization and the heaters would not have operated. Due to

the licensee's failure to change the dP setpoints, it appears

that the train A heater may have operated under normally

expected ventilation entditions, but the train B heater would

4

only sporadically operate because under existing venti ution

conditions, the fan dP was about equal to the dP setpoint.

Subsequent to the electrical modifications on November 6, 1987,

it appears that the train B heater would continue to operate

sporadically, but the train A heater now would not operate

under normally expected ventilation conditions. 7 esign

operation of the heaters would be expected subsequent to the

setpoint changes on November 7, 1987, and November 20, '.987,

for Train A and Train B, respectively.

(2) Without the heaters operational to assure 70% relative humidity

(T/S laboratory test RH for charcoal adsorber acceptance), the

intake of makeup air of greater than 70% RH would lead to less

adsorber efficiency than that for which the charcoal has been

tested and would thus lead to higher Design Basis Accident (DBA)

control room operator thyroid doses than anticipated. Under

certain conditions (DBA conditions with high relative humidity),

the control room potentially could htve been uninhabitable per

GDC-19 criteria. If the control room was uninhabitable, a

condition would exist which could prevent the fulfillment of

the safety function of systems needed to shutdown the reactor

and maintain a safe shutdown condition.

The licensee's safety analysis of this event contends that only

the main steamline break accident is postulated to significantly

affect turbine building relative humidity (100% RH). A humidity

sensor located in the turbine building emergency makeup air

intake would reportedly annunciate in the Main Control Room to

alert the operators. Makeup air from the minimum outside air

intake can be established by opening the normally closed damper

and closing the turbine building emergency :.iakeup air intake

damper. The licensee claims that the source of moisture in the

air could thus be removed. It should be noted, however, that

because the turbine building is not a Seismic Category I

structure, no credit is given for that building's presence in

accident :nalyses; nor did the NRC give credit for dual emergency

air intakes. Also, as discussed above, inoperable heaters will

allow atmospheric relative humidity to impinge on the charcoal

adsorbers which will then have a lower iodine remw al efficiency

than if the heaters were operating; this is true for all relative

6

-

- .

. .

...

. ...

. .

humidities and types of radioiodine release accidents. For these

reasons, the licensee arguments appear to be invalid.

(3) Another potential problem resulted from the design and .=etpoint

errors in that the heaters would operate at less than their

design air flow. The heat removal by air flow would thus be less

than designed, and the heater would tend to raise the temperature

of the air impinging on the charcoal adsorbers. Although the

probability of a charcoal fire may be only slightly increased,

' the licensee has committed to the heater design required of

ANSI /ASME N509-1976. (ANSI /ASME NE.09-1976, Section 5.5 states

that the sensible heat produced by the heater shall not result

in increasing air temperatures to more than 225 F and a manual

overtemperature control switch set at this value shall be

provided.) Nevertheless, it appears that under some low flow

conditions, charcoal combustion may have been possible. Until

this matter is reviewed further, it is cont.idered an Unresolved

Item. (456/88007-01)

e. Quality Assu 3nce Regulatory Raquirements

Appendix B to 10 CFR 50 defines the required quality assurance ,

'

criteria for nuclaar power plants to assure safe operation, ,

including quality assurance requirements for design, construction, +

and testing of systems that mitigate the consequences of postulated '

accidents that could cause undue risk to the health and safety of '

the public. As used in this appendix, quality assurance comprises

all actions necessary to provide adequate confidence that systems i

and components will perform satisfactorily in service.

(1) Design Control

Commonwealth Edison Company Quality Procedure No. 3-1, Design ;

Control, Section 4.2, states that design review and control is ;

required to assure meeting design and regulatory requirements. ;

Commonwealth Edison Company Quality Procedure No. 3-2, Design

Change Control, Section 3.6, identifies an Engineering Change ,

Notice (ECN) as a design change by the Architect Engineer (A/E)

which documents and authorizes design changes engineered and

issued by the A/E; Section 2.0, states that design reviews are

conducted within the participating departments on each design !

change. The Braidwood Startup Manual is a procedure which

provides requirements for the completion and initial testing

of the plant in conformance with the requirements of the

Commonwealth Edison Company Qcality Procedures and Appendix B

of 10 CFR 50. j

i

,

D

)

7 >

. ~ _ , . _ _ _ . - _ _ _ , , _ - , - . _ _ _ _ _ _ _ _ . _ _ _ _ _ _ _ - - _ .

-

. . .

. ..

'

.'...

.. .

p

i

Contrary to the above, the design control measures were !

inadequate to correctly implement Design Change No. VC-041 i

to the Control Room Ventilation Systems' heater interlock i

control systems:

Adequate measures were not established for coordination

among participating design organizations in that ECN

No. 34272 generated by the A/E's Control and Instrumentation 1

Division was improperly understood and incorrectly ,

incorporated into ECN No. 34446 by the A/E's Electric Project *

Engineering Division.

Adequate measures were not provided for verifying or )

checking the adequacy of design in that a design review -

was not adequateiy performed to assure that the design

change initiated by ECN No. 34446 was proper by verifying ,

or checking the adequacy of design, such as by the

performance of adequate design reviews or by the performance

of a suitable testing program, i

Failure to meet the requirements of the Startup Manual and

Quality Procedures Nos. 3-1 and 3-2 is an apparent violation [

of Criterion III, Design Control, Appendix B to 10 CFR 50. .

(456/88007-03) >

(2) Test Control t

Commonwealth Edison Company Quality Procedure No. 11-2, !

Development, Performance, Documentation and Evaluation of ;

Preoperational and Startup Tests, Section 3.2, states that *

preoperational tests are tests made prior to initial

criticality to demonstrate the satisfactory mechanical and

electrical operation of the systems involved, including

interlocks between systems. The Braidwood Startup Manual is

a procedure which provides requirements for the completicn and ,

initial testing of the plant in conformance with the reqilirements

of the Commonwealth Edison Company Quality Procedures and ,

.

Appendix B to 10 CFR 50. This manual states in part, that a

preoperational test will demonstrate the capability of systems i

and components to safety related performance requirements, a

component demonstration i a test completed to reverify proper

operation af ter a control circuitry change, and a retest is a i

l

test necessary to complete steps omitted during the execution ,

'

or to repeat test sections. ;

,

I

l Preoperational Test BwPT VC-10, Control Room Ventilation,

j was performed on March 4 and 11, 1987, on trains B and A,

respectively. These tests, as well as retests on train A ,

l

on March 30 and April 3,1987, and on train B on April 4, l

1987, indicate that the Control Room Ventilation Systems'

l heaters were operating. On April 15, 1987, Deficiencies (DEF) t

Nos. VC-10-520 and VC-10-521 were initiated to complete i

r

ECN No. 34446 for train B and A, respectively. On May 20, .

!

,

t

! f

8

'

_ _ _ . - - - - . -- . _ , _ ,

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ . _ _ _ _ _ _

.

'

. . .- ...

. .

1987, DEF Nos. VC-10-520 and 521 were closed. Initial

criticality for Unit 1 occurred at 2120 on May 29,1987; VC was

declared operational by Technical Specifications. Because the

licensee did not conduct a component demonstration or a retest

after completion of ECN No. 34446, the licensee was apparently

unaware until it was identified during a review of the VC startup

test on November 6, 1987, that design change errors jeccardized

the operability of the Control Room Ventilation Systeus. The

failure to meet the requirements of the Startup Manual and

Quality Procedure No. 11-2 is an apparent violation of

Criterion XI, Test Contro', Appendix B to 10 CFR 50.

(456/88007-04)

(3) Instructions, Procedures, and Drawings

On February 9, 1987, the setting of 5.73" wg was specified on

design drawing instructions for differential pressure switches

on train A (OPOS-VC059, Sheet No. PS631) and train B (0PDS-VC060,

Sneet No. PS633) for the heater interlock logic circuitry of the

Control Room Ventilation Systems. On November 7, 1987, the

as-found setpoint un train A was 16.5" wg; on November 20, 1987,

the as-found setpoint on train B was 13.2" wg. The failure to

reset the setpoints on these switches after the completion of

ECN No. 34446 and to verify the setpoints as part of the

preoperational test program pursuant to the requirements of

the Startup Manual is an apparent violation of Criterion V,

Instructions, Procedures, and Orawings, Appendix B to

10 CFR 50. (456/88007-05)

f. Safety Review Regulatory Requirement

The Braidwood Final Safety Analysis Report (FSAR), Section 6.5.1

states that each control room HVAC makeup air filter unit utilizes

heaters to assure optimum air conditions entcring the charcoal

absorbers. Appendix A of the FSAR indicates, in response to

Regulatory Guide 1.52 Position 3.b, that the heater stage is sized

to reduce the relative humidity of the 9ntering air-steam mixture

from 100% to approximately 70%. FSAR Subsection 7.3.1.1.9 states

that the electric heating coils are interlocked with the

corresponding standby makeup air fans; FSAR Subsection 9.4.1.4

states that the interlocks are cold checked, adjusted, and tested

to ensure the proper sequence of operation. The calculated LOCA

control room operator doses presented in Table 6.4-1 of the FSAR

are based on iodine removal efficiency credits of 99% and 90% for

the control room makeup air intake and recirculation charcoal

absorber filters, respectively. Assuring these iodine removal

efficiencies is dependent upon maintaining relative humidity at

or below 70%, as specified in T/S 4.7.6.a.2 and T/S 4.7.6.h.2.

The basis for T/S 3/4.7.6 states that the operability of the Control

'

Room Ventilation System ensures that the centrol room will remain

habitable for operations personnel during and following all credible

accident conditions based on limiting the personnel radiation exposure

consistent with tne requirements of GDC-19.

9

-

~

_ _ _ . - -_____ _________________ ___ __--__ _____ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ - _ _

'

, ..

. .

The licensee made changes in the facility as described in the

safety analysis report without prior Commission approval even

though the change involved an unreviewed safety question, when

on May 20,1987, the licensee ircorrectly implemented a design

change to tte Control Room Ventilation System heater interlock

control system which shut the heater off when the fan dP setpoint

was reached rather than the desired change which was to turn the

heater on when the fan dP setpoint was reached.

This is an apparent violation of 10 CFR 50.59(a)(1) which prohibits

a licensee from making changes in the facility as described in the

safety analysis report, without prior Commission approval, if the

proposed change involves an unreviewed safety question.

10 CFR 50.59(a)(2) states that a proposed change shall be deemed

to involve an unreviewed safety question if, among others (i) the

consequences the of an accident previously evaluated in the safety

analysi:, report may be increased; or (ii) a possibility for a

malfunction of a different type than any evaluated previously

in the safety analysis report may be created; or (iii) the margin

i

of safety as defined in the basis for any technical specification

i

is reduced. (456/88007-02)

g. Technical Specification Limiting Conditions for Operation

Technical Specification 3.7.6 LCO, states that two independent

Control Room Ventilation Systems shall be operable for all

operational modes and that for modes 1, 2, 3 and 4, with one Control

Room Ventilation System inoperable, restore the inoperable system to

operable status within 7 days or be in at least hot standby within

the next six hours and in cold shutdown within the following 30 hours3.472222e-4 days 0.00833 hours 4.960317e-5 weeks 1.1415e-5 months .

Technical Specification 3.0.3 LCO, states that when an LCO is not

met, except as provided in the associated action requirements, within

one hour action shall be initiated to place the unit in a mode in

which the specification does not apply by placing it, as applicable,

in at least hot standby within the next six hours, at least hot

,

shutdown within the following six hours, and at least cold shutdown

j within the subsequent 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months .

,

The train B heater was apparently operable on October 1 and 19, 1987,

l during surveillance tests; yet the train B heater tested inoperable

during the October 2, 1987 startup test and on November 6, 1987.

The apparent contradictions in ope ability test results may be due

t to the nearness of the fan dP to tie heater interlock logic switch

setpoint. The fan iip measured 13.0" wg on October 2, 1987; the

as-found setpoint on November 20, 1987 was 13.2" wg. Thus, it

appears that at least between October 2,1987 anci November 6,1987,

train B operability was sufficiently in doubt and it should have

been declared inoperable on October 2, 1987.

l

'

10

!

- . _ - . .- . _ . _ _ _ -. ._

- _ _ _ _ _ _ _ _ _ - __ _______ ____ __ __________ _ _ _ . _ _ _ _ _ _ _ _ ___ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

'

.

. . . 7

. .

Af ter the heater interlock logic switches were rewired on November 6,

1987, to correct the design errors, train B was declared operable at

1234. Later in the day it was discovered by station technical staff

engineers that the setpoints on both trains were incorrect. This

'

discrepancy combined with the rewired logic switches made it

unlikely that train A was operable and put the operability of

train B in significant doubt. It appears that both trains should

have been declared inoperable and the action requirements of T/S 3.0.3

entered when the failure to reset the switch setpoint was identified.

Instead, after setpoint readjustment the licensee exited the LC0

action requirement (AR) of T/S 3.7.6 for train A at 0820 on

November 9, 1987, entered T/S 3.7.6 LCO AR to reset setpoint on the

train B heater interlock logic switch at 0853 on November 20, 1987,

and exited train B T/S 3.7.6 LC0 AR at 1342 on November 21, 1987.

The licensee appears to have been in violation of the T/S 3.7.6

LCO AR at least intermittently between October 2, 1987 (perhaps

since initial criticality on May 29, 1987), and 1342 on

November 21, 1987, and of the T/S 3.0.3 LC0 AR between 1235 on

November 6, 1987, and 0820 on November 9, 1987. (456/88007-06)

5. Exit Meeting

The inspector met with licensee representatives (denoted in Section 1) at

the conclusion of the inspection on March 4, 1988, and by telephone on

March 17, 1988. The inspector summarized the scope and findings of the

inspection, including the unresolved item and the apparent violations.

The inspector also discussed the likely informational content of the

inspection report with regard to documents or processes reviewed by the

inspector'during the inspection. Tre licensee did not identify any such

documents / processes as proprietary.

!

I

r

l

1

l

l 11

!

1

._-_ _

. - - - _ _ - - . - . . . . .. .. .-

i

. .' r '.'

.- .

- i

Appendix A l

Sequence of Relevant Events

.

Date/ Time Event Description

October 14, 1986 Fan dP interlock switch (0PDS-VC059) on

train A set at 16.1" wg with the switch in

the normally closed pos* tion. (The switch

was designed to open upon Hi-dP across fan ,

0VC03CA, thus turning the fan off.) ;

'

tober 23, 1986 Design Change VC-041 was initiated to delete

fan OVC03CA/CB high delta P trip and add low e

'

flow trip and heater interlock. (Based on

Byron experience.)

December 16, 1986 Engineering Change Notice (ECN) No. 34272

approved by S&L's C&I Division in response

to DC-VC041.

December 16, 1986 ECN No. 34446 approved by S&L's EPE '

Division in response to ECN No. 34272.

NOTE: ECN 34446 was based on a roisunderstanding of ECN 34272 which !'

resulted in switches OPDS-VC059 & 060 remaining in the normally

closed (NC) position when used as heater interlock switches. !

Thus, when the fan started the heater would start and run t

until the fan dP setpoint was reached, f

December 16, 1986 Fan dP interlock switch (OPDS-VC060) on i

Train B set at 16.0" wg with the switch in

the nonna11y closed position. -

February 9, 1987 The setting of 5.73" wg was specified on

differential pressure switches on Train A I

'

(0PDS-VC059, Sht. No. PS631) and Train B

(0PDS-VC060, Sht. No. PS633).

March 4, 1987 Preoperational Test BwPT VC-10 "Control

Room Ventilation," was performed on Train B.

The heater generated about 30 amps, j

March 11, 1987 VC-10 performed on Train A. The heater

generated about 30 amps.

March 30, 1987 Retest No. 146 was performed on Train A; ;

reason for retest was unrelated to heater l

nerformance. The heater generated about !

30 amps. I

i

?

l

-..,-.,,.,,.,n_- - - . - - - - . - - , , , , , , _ . , . , , , , . , ,-- r,--, - ---

_ _ _ _ _ _ _ . - _ _ _ _ _ _ - - _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ - _ _ . _ _ _ - _ _ _ _ ____ _ _____ ____ . _ _ _ _

, lt

.\

. .

.

Appendix A 2

April 3, 1987 Retest No.147 was performed on Train A;

reason for retest was unrelated-to heater

performance. Heater contacts reported

closed.

April 4, 1987 Retest No. 147 was performed on Train B.

Heater contacts reported closed.

April 15, 1987 Deficiencies Nos. VC-10-520 and VC-10-521

written to complete ECN No. 34446 for train

B and A, respectively.

May 1, 1987 Retest No. 149 was performed on Train A;

reason for retest was unrelated to heater

performance. The dT across the filter unit

was 11-12'F; criteria for indication of ,

heater function is a minimum of 5'F dT.

May 12, 1987 Electric construction on train B regarding

DEF No. VC-10-520 completed.

May 15, 1987 RewurS. reverification complete for DEF No.

VC-10-520.

May 16, 1987 Electrical construction on train A

regarding DEF No. VC-10-521 complete.

May 19, 1987 Rework reverification complete for DEF

No. VC-10-521.

May 20, 1987 DEF Nos. VC-10-520 and 521 closed.

NOTE: At this point in time the design changes required by ECN No. 34446

were complete; however, the heat'.r interlock logic switches were

wired in the wrong position (NC rather than the correct N0 setting)

and the fan dP retpoints had not been revised to the correct vslue

(5.73" wg). The root cause for incorrect wiring diagram in ECN

No. 34446 is discussed above (December 16, 1986 ECN approval date).

In accordance with the startup manual, the modifications of the

interlock logic switches appear to require either retests or, at

least, component demonstrations to verify the adequacy of the

design change; neither type of verification was performed.

The standard preoperational testing practice was to complete all

setpoint changes after any required design changes on affected

) components were completed without a specific setpoint change

f request. However, reportedly contractor instrument maintenance

personnel assumed this instruction only applied until fuel load.

Because the VC system was not required to be operational until

initial criticality the setpoints erroneously remain unchanged.

_

,

.s

'

_ , :r 7

e- e ,

Appendix A 3

i

!

Mey 23, 1987 Preoperational Test Program for VC

completed. '

May 29, 1987 @ 2120 Initial Criticality for Unit 1; VC delcared

operable.

,

September 30, 1987 Startup Test BwSu VC-30, "Heat Capacity

Verification for Control Room HVAC System,"

was performed on Train A. Because heater

amps / volts were not measured, Deficiency ,

B-501 was written. The resolution of DEF

B-501 was that heater operation would not

affect ovarall test acceptability; therefore

no retest was required for the heater.

September 30, 1987 thru Surveillance Procedure No. OBw0s 7.6.8-1 was i

October 1, 1987 performed on Train B. Filter Unit dT was ,

7*F; criterion for heater function is a i

minimum dT of 5 F.

!

October 2, 1987 Startup Test VC-30 was performed on Train l

B. Proper heater voltage was measured; '

however zero amps were measured. l

NOTE: The response of the startup test personnel was inadequate in that ,

personnel did not realize that heater operability is directly tied

by the Technical Specifications to the Control Room Ventilation

System operability. The startup test procedure was apparently

inadequate in that heater operability, including setpoint ,

verification, vas not part of the overall test acceptability

,

criteria. ,

b

1 October 3, 1987 Surveillance 7.6.B-1 was performed on train !

A; filter Unit dT was 8 F. >

October 18-19, 1987 Surveillance 7.6.B-1 was performed on tra'n 7

l B; filter unit dT was 16*F.

l

l November 3, 1987 Surveillance 7.6.B-1 was performed on train

A; filter unit dT was 10*F. ;

!

l

NOTE: The train B heater was apparently operable on October 1, '987 and .

October 19, 1987; yet the train B heater tested inoperable on t

October 2, 1987 and November 6, 1987. The apparent contradictions l

in operability test results may be due to the nearness of the fan

dP to the heater interlock logic switch setpoint. The fan dP r

measured 13.0" wg on October 1, 1987; and the as-found setpoint [

on November 20, 1987 was 13.2" wg.

I

.

A

L

- _ ___ _ _ _ . _ _ __ . _ _ _ _ _ _ _ _ _ _ _ - _ _ _ _ - . _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

.,." .'s ;

. .

Appendix A 4 !

,

!

November 6, 1987 The licensee's Project Engineering I

@ approx. 1100 Department (PED) notified the station that l

during a review of the startup test VC-30 !

and Engineering Design Change DC-VC041, it

was noted that the train B heater did not .

energize.

'

After consulting with Sargent & Lundy, the

licensee confirmed that an error in design

existed in the heater interlock icgic

circuitry and the heaters on both trains l

(A&B) would not energize at the proper time. ,

November 6, 1987 @ 1135, 61% Both trains of VC were declared inoperable

reactor power and T/S 3.0.3 was entered (T/S 3.7.6 LC0 ;

Action requirement 1.a was entered for Train

A). LCO AR-1.a states that in modes 1, 2, 3 ;

and 4; with one control room ventilation 1

system inoperable, restore the inoperable !

system to operable status within 7 days or !

be in at least hot standby with the next 6 .

hours and in cold shutdown within the '

following 30 days. E

NOTE: Upon declaring both trains of VC inoperable, the licensee's

Electrical Maintenance Department (EMD) was contacted to determine '

if the train B heater would energize with the emergency fan running.

The component check of the B train heater revealed that the heater

'

was energized as soon as the fan was started but de-energized after i

the fan had been running for a few seconds. Train A was not tested.

If train A had been tested, the heater may have energized. The fan

dP for Train A measured on September 30, 1987, was 11.5" wg; the

as found setpoint on November 7, 1987 was 16.5" wg.

After installation of temporary alterations (changing switches

OPDS-VC059 and OPDS-VC060 from the NC to the N0 positions) of

both trains of VC by EMD, the train B heater was again tested; i

the heater was found to energize shortly after the emergency

fan began operation and to remain energized. Train A was not

tested; because of the still undiscovered setpoint error, it

is likely that train A would have failed the component test.

November 6, 1987 0 1234 T/S 3.0.3 is exited; Train A remained in T/S

3.7.6 LCO Action Requirement 1.a.

NOTE: The heaters are energized only if the fan energizing contacts and

the fan dP contacts are both closed (an AND interlock logic gate).

Thus it was expected that with the fan dP heater interloch switch

in the incorrect NC position, the heater would come "on" when the

-__ _ _ _ _ _ _ _ . ._. ___ _ _ _ _ _ . _ - _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ - _ _ _ _ _ _ _ _ _ _ _ _ _ _ - _ _ _

.. *:

. .

Appendix A 5

fan was started and turn "off" when the fan dP setpoint was reached.

Likewise, when the fan dP heater interlock switch was in the

correct N0 position, it was expected that the heater would not turn

"on" until the fan dP setpoint was reached. Although the train 8

heater behaved as expected, it did so at a later time after fan

start than expected.

Station technical staff engineers reviewed setpoint data shee s to

determine that the setpoint changes required by the design change

specified by ECN No. 34446 had not been completed. Since train A

was in T/S 3.7.6 LC0 AP.-l.a and train 8 had been demonstratad

operable, no change in LC0 AR's were deemed necessary by the

licensee. Setpoint change request for train A was initiated

on November 6, 1987.

November 7, 1987 Train A switch OPDS-VC059 as-found setpoint

was 16.5" wg; the as-left setpoint was

5.75" wy. The setpoint had drifted up from

the October 14, 1986 value of 16.1" wg.

November 9, 1987 00820 Train A T/S 3.7.6 LCO-AR-1.a was exited.

November 9, 1987 Setpoint change request for train B was

initiated.

November 20, 1987 00853 Train B T/S 3.7.6 LC0AR-1.a was entered.

November 20, 1987 Train B switch OPDS-VC-060 as-found setpoint

was 13.2" wg; the as-left setpoint was 5.70"

wg. The setpoint had drifted down from the

December 16, 1986 value of 16.0" wg.

NOTE: Switches OPDS-VC059 and 060 were initially high delta P fan trips

both at Byron and Braidwood. The switch was converted to a heater

interlock logic switch, in part, because setpoint drift at Byron

resulted in spurious fan trips.

November 21, 1987 @l342 Train B T/S 3.7.6 LC0 AR-1.a was exited.

ML20150E992

Text

Navigation menu

Search