ML20214N813

Safety Insp Rept 50-295/87-12 on 870508-12.Major Areas Inspected:Events Surrounding Inadvertent Opening of All Four MSIVs & Subsequent Safety Injection on 870430.Event Caused by Communications Error & Failure to Refer to Procedures

ML20214N813
Person / Time
Site:	Zion File:ZionSolutions icon.png
Issue date:	05/26/1987
From:	Hinds J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
To:
Shared Package
ML20214N792	List: ML20214N790 ML20214N813
References
50-295-87-12, NUDOCS 8706030086
Download: ML20214N813 (10)

See also: IR 05000295/1987012

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U.S. NUCLEAR REGULATORY COMMISSION

REGION !!!

Report No. 50-295/87012(DRP)

Docket No. 50-295 License No. OPR-39

Licensee: Coninonwealth Edison Company

P. O. Box 767

Chicago, IL 60690

Facility Name: Zion Nuclear Power Station, Unit 1

Inspection At: Zion, IL

Inspection Conducted: May 8 through May 12, 1987

Inspectors: M. M. Holzmer

P. L. Eng

N. Williamsen

" J i L g . c'.

Approved By. M. Hinds, Jr ting Chief f.24 J7

Reactor Projects Section 1A DTie

Inspection Sunenary

inspection on May 11 thrnugh May 12, 1987 (Report No. 50-295/87012(DRp)

Areas inspected: Special safety inspection of events surroundin

opening of alTTour Unit 1 main steam isolation valves (MSIVs) g inadvertent

and subsequent

safety injection on April 30, 1987.

Resu_I ts: One Unresolved Item was identified regarding this event. The

inspection disclosed that this was a significant event in that all four MSIVs

were open and unable to close automatically or manually from the control room

for approximately 20 minutes. The event was caused by a coninunications error

and by a failure to refer to procedures,

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DETAILS

1. Persons Contacted

• G. Plim1, Station Manager

• E. Fuerst, Superintendent, Production

• T. Rieck, Superintendent, Services

• W. Kurth, Assistant Station Superintendent, Operations

L. Pruett, Unit 1 Operating Engineer

N. Valos Unit 2 Operating Engineer  !

R. Cascarano, Technical Staff Supervisor

T. Printz, Assistant Technical Staff Supervisor

• C. Schultz, Regulatory Assurance Administrator

• J. Dallard, Quality Control Supervisor  !

• W. Stone. Quality Assurance Supervisor

• P. LeBlond, Licensing Administrator

• T. Droccolo, Assistant to Assistant Station Superintendent, Operations

• T. Wenig Engineer. Technical Staff

• G. Wagner, Maintenance Manager, Corporate Office

• J. Harbin, Shift Engineer

The inspectors also met with and interviewed shift supervisors, licensed

operators, and non-licensed operators.

• Indicates persons present at exit interview.

2. Safety In'ection JST)_ Due to inadvertent _ Opening of All Four Unit 1 Main

5 team tim atton valves (H51vl

a. _Dackground

The MSIVs at Zion are hydraulically opened, pneumatically shut. 35

inch globe valves. Hydraulic oil is piped to the underside of the

MSIV actuating piston, and nitrogen pressure is maintained above the

piston (scoAttachment1). When the hydraulic oil pum) is running i

andnohydraulicdrainvalvopathsareopen(seeAttachment2),the  !

MSIV will open. When either one of the two trip solenoid valves l

(D A E in Attachment 2) are open, oli pressure will bleed of f and  !

nitrogen pressure will overcome hydraulle pressure, forcing the MS!V -

closed. The trip solenoid valves aro "energiro to open" valves and -

areenvironmentallyqualified(EQ). To maintain their EQ status,

the licensee has procedurally limited the length of time tno trip i

solenoid valves can remain energized by requiring that the fuses to

the trip solenoid valves will be removed if the M"ilVs are to remain

closed longer than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />,

b. Event _ C_hr_on_o_ logy

On April 30, 1987 UnitIwasinhotshutdown(Mode 3)atnormal

operating temperature and grossure, with all four M$lys closed, j

Operators had just placed OutofService"(005)tagsonthemain

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steam system for personnel protection for Unit 1 generator work.

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Zion procedures require that when the MSIVs are to be closed for

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more than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, the fuses for the MSIV trip solenoid valves

l are to be removed in order to de-energize the MS!V trip solenoid

l valves. This is for environmental qualification reasons (See

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paragraph 2.c). At about 11:00 a.m. due to a communications error

between the Shif t Control Room Engineer (SCRE) and the equipment

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oaerator (EO), the E0 removed the MSIV trip solenoid fuses before

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tie MSIV hydraulic pumps were secured. As the fuses for the MSIV

l trip solenoid valves were pulled, all four MSIVs opened sequentially,

pressurizing the main stcam lines. Asafetyinjection(SI) occurred

due to high steam delta prescere for Loop B caused by the sequential

steam readmission. Water was injected by the centrifugal charging

pumps through the boron injection tank to the reactor coolant system

for approximately six minutes. Steam header pressure increased

from approximately 80 psig to about 785 psig in four minutes. 1

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Reactor coolant system (RCS) temperature decreased 27'F to about

516*F.

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The licensee responded to the SI por their Emergency Response

Guidelines (ERGS). The SI was terminated in about six minutes.

An Unusual Event was declared at 11:20 a.m. in accordance with the

licensee's Generating Station's Emergency Plan. The MSIVs remained

open untti the licensee removed power to the four MSIV hydraulic oil

pumps and opened hydraulic valves R8 (see Attachment 2) for each

MSIV to allow nitrogen pressure to close the MSIV.

The Unusual Event was terminated at 11:50 a.m.

c. Root Causes And Other problems

(1) Failure to provide and roccive precise verbal coninunications.

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Poor conrnunications resulted in the E0 interpreting a question

about pulling the MSIV fuses as an order to perform the task.

The SCRE did not intend to provide an order aut was requesting

confirmation of the next sequence of events. Verbal repeat i

back of the order was not required nor was it performed.

(2) Failure to review the applicable system operating instruction  !

prior to removing the MSIVs from service.  !

$1nce System Operating Instruction, 501-31 " Main Steam", was  :

not reviewed by the E0 prior to pulling the fuses, the need to

have the MSIV hydraulic pumps de energized was not identified. j

The E0 would nomally perform the removal of the fuses as part l

of $01 31.  !

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I (3) The design of the MSIV hydraulic system requires that when

the MSIVs are closed the trip solonutd valves must remain

energized. However, to maintain the solenoid environmental  :

qualifications, thit length of time during which they must  !

remain energized must be limited. Thus to keep the MS!Vs

closed for long periods of time other measures must bu taken. ,

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(4) The 00S for the main steam system was apparently inadequate

and in violat10n of the licensee's 005 procedure.

(5) The licensee took approximately 25 minutes to close all

four MSIV's by opening the MSIV hydraulic pump breaker and

opening valve R8. The MSIVs could have been more quickly

closed from the control room if the MSIV fuses had been

replaced,

d. Corrective Actions

The licensee stopped all non-esser.tial operations department work,

including 005 tagging and changes to plant conditions until each

operating shif t was briefed regarding the event and interim steps

to prevent recurrence. Briefings were held before each shift was

allowed to resume normal activities.

The licensee's subsequent corrective actions are listed below.

The status of each item is provided.

Expedite engineering review of the design of the MSIV system

to include the fail state of the valve as well as the energized

life of the solenoids.

Status: Station Nuclear Engineering Department (SNED) was

requested to perform the review following a station modification

review connittee meeting on May 12, 1987.

Install warning plaques on the MSIV trip solenoid fuses and

hydraulic pump motor control centers (MCCs) to ensure the

proper sequence of de-energizing the valves.

Status: Temporary warning si

and MCCs on Saturday, May 2, gns

1987, finalwere placed

Wording Was on the fuses

determined on May 5, 1987, and permanent signs were installed

by May 9, 1987.

• Initiate procedure changes to require operators to log the

procedure and the step numbers that apply to current plant

conditions and evolutions. The changes would also require

that the appropriate section of that procedure be reviewed

by the oncoming operator, prior to shif t change.

Status: In place May 1, 1987 by Standing Order 87-11.

Permanent procedure changes will be made through the normal

process.

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Require that all completed steps of key procedures be

properly signed off, rather than marked with a check mark.

Status: Inplemented by Night Order May 2, 19075 made permanent

by Standing Order 01 12, May 6, 1907. This was formerly the

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practice for Periodic Tests (pts) and Maintenance Instructions

(mis). All General Operating Procedures (GOPs) with the

exception of G0P-3 are now corrected per this standing order.

Formal procedure changes will follow through the normal process.

Implement and train on formal " repeat-back" communication.

Status: Initially communicated to each shift verbally

immediately following the incident and prior to each shift

performing any shift activities. This was followed by

Standing Order 87-11 on May 1, 1987. Procedure changes will

follow by the normal process. Additional instructions will

be given during each crew's subsequent training weeks. The

first such session will take place on May 15, 1987.

Review System Operating Instructions (501's) to determine if

they should be made " mandatory-in-hand" procedures.

Status: Initial review has been completed and the above change

will not be made at this time. However, Standing Order 87-11,

dated May 1, 1987, requires a review of procedures prior to any

particular evolution, to determine whether an S0I (or other

procedure) pertains to the evolution. If a procedure does exist,

it must be reviewed prior to the evolution; if not, then pre-

cautions and limitations of the associated S0I must be reviewed

for applicability.

The above requirement, specified in Standing Order 87-11

May 1, 1987, will be updated to require the Shift Engineer to

determine whether a procedure is needed, for those evolutions

or conditions where presently there are no procedures.

Review the method of control of orders given to operators.

Status: The control of orders given to operators has been

more clearly defined in Standing Order 87-13, dated May 7,

1987. In addition, Standing Order 87-13 changes the division

of responsibilities between the shift Control Room Supervisor

(normally the SCRE) and the shift's Second Licensed Foreman,

in order to distribute the workload more evenly. This change

allows the SCRE to devote more attention to unit operation.

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Licensing will perform a review to determine whether an

unanalysed condition existed for this event.

Status: The completed review is expected by May 15, 1987.

" Review the shift's actions on April 30, 1987, in response to

the Safety Injection.

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Status: The operating department management met with the

shift personnel and concluded that the actions taken were

fully consistent with the Emergency Response Guidelines

(ERGS) and that the reclosing of the MSIVs was done in a

conservative and timely fashion.

NRC interviews of shift management and review of plant parameters

from computer graphs revealed that the steam header pressurized

in about 5 to 10 minutes. Thus the event was essentially

terminated prior to closing the MSIVs. Shift management stated

that by the time they had proceeded through the ERGS for SI and

SI termination, they felt they could take more time and be more

deliberate than they could if there was a continuing steam demand.

The shift management stated that there were conflicting

indications, which could out be verified by personnel in the

control room, regarding the position of the MSIV hydraulic

pump breaker. For that reason, they chose to ensure that

the breaker was open prior to opening MSIV hydraulic valve

R8. Because the flow rate through R8 is approximately the

same as the capacity of the hydraulic pump, opening R8 with

the pump energized would not ensure that the MSIV's would close.

• Incorporate the applicable steps of S01-31, " Main Steam", into

the GOPs, where possible.

Status: This is under evaluation and the conclusions will be

documented.

" Review the depth and extent of the Operating Engineer's (0E)

control over the shift, through the Shift Engineer (SE).

Status: This review has been done by the Production

Superintendent and the Assistant Superintendent-0perations

and OE control is deemed adequate.

• Review the out-of-service (005) practices at Zion, since

initially MSIV's were not taken 00S properly.

Status: Although the licensee believes that the improper

005 was not a cause of the SI, 00S practices are still of

concern to the licensee because the MSIV 005 was apparently

not in accordance with Zion's procedures. Initial review

indicated that the 005 problem was confined to the MSIVs.

Zion station procedures stated that "Where it is possible to

energize or liven the equipment from more than one source,

the appropriate Out Of Service Card shall be placed on all

isolating devices (switches, valves, etc.) before the work

is started. It is not sufficient to attach an Out of Service

Card to a remote switch only." The Assistant Superintendent-

Operations had follow-up discussions with each crew regarding

the standing orders issued and this 00S problem on May 6, 1987

through May 8, 1987.

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• Mandate that the " center desk NS0" issue all 00S jobs to

nonlicensed operators.

Status: This has been the practice at Zion. In the

discussion with the shift crews on May 6, 1987 through May 8,

1987 on 00S practices this was re-emphasized as the accepted

practice for issuing 00S jobs to the A and B operators for

write-up and card hangings.

(e) Safety Significance:

Unit I was in hot shutdown (Mode 3) at normal operating temperature

and pressure. The Reactor Coolant System (RCS) was cooled 27

degrees during the event. RCS pressure never exceeded 2280 psig.

The licensee determined that 3% of the design SI cycle life had

been used as a result of this transient. The Unit was in a condi-

tion for approximately twenty-five minutes during which all four

MSIVs were open and unable to be closed by an automatic signal, or

by manual action from the control room.

The secondary plant main steam headers were pressurized from 80

psig to about 800 psig in about four minutes. The main steam

lines saw a total heat up of about 200 degrees during the period

of pressurization. Since the MSIV's were closed only seven hours

earlier, the main steam lines had not cooled significantly from

normal operating temperature of 500 F prior to the re-pressurization.

A walkdown of containment and secondary steam piping did not

identify any damage. There were no personnel injuries as a result

of this event.

Section 14.2.5.3 of the Zion Final Safety Analysis Report (FSAR)

states that the MSIVs are designed to close within 10 seconds of a

large steamline break, and that for any break in any location, no

more than one steam generator (SG) would blowdown, even if one of

the isolation valves fails to close. Had a large steamline break

occurred during the April 30, 1987 event, the MSIVs would have been

incapable of both automatic and manual closure from the engineered

safety feature logic system (ESF). For any steamline break

downstream of the main steam check valves, all four SGs would have

blowndown. This would have constituted an unanalyzed condition.

(f) Inspector Comments

(1) The event occurred at 11:00 a.m. on April 30, 1987. The

event was reported to the NRC at 11:46 a.m. the same day.

This was within the one hour requirement of 10 CFR 50.72

(a)(3 for declaration of Emergency Classes (eg Unusual

Events .

(2) The licensee's corrective action was prompt as shown by the

stop work, immediate shift briefings, and series of Standing

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Orders. The extent of the corrective actions exceeds that

shown in responses to previous operating events, especially

as it pertains to communications and enforcement of procedural

adherance.

(3) Past performance in the operating area has been average.

Ratings given in NRC's Systematic Assessment of Licensee

Performance have been Category 2 (average) for the last 3

assessment periods. Communications have been adequate in

most cases, but are generally casual. Adherance to GOPs has

been very good, but S0Is have not been rigorously used.

Several events have occurred since the beginning of the year

involving failure of operators to adhere to procedures, or

erroneous assumptions on the part of operators regarding. plant

conditions or evolutions in progress.

(4) No specific notices had been given to the licensee by licensee

audits, or NRC or industry notification regarding similar

events.

(5) This is the first SI at Zion since January of 1984. Other

violations of operating procedures have occurred, but

their safety significance has been classified as minor. .

(g) Evaluation

This is considered an Unresolved Item per. ding review by a Region III 2

Enforcement Board (295/87012-01(DRP)).

3. Unresolved Items

Unresolved items are matters about which more information is required in

order to ascertain whether they are acceptable items, violations, or

deviations. One Unresolved Item disclosed during this inspection is

discussed in Paragraph 2.

4. Exit Interview

The inspectors met with licensee representatives (denoted in Paragraph 1)

throughout the inspection period and at the conclusion of the inspection

on May 12, 1987, to summarize the scope and findings of the inspection

activities. The licensee acknowledged the inspectors' comments.

The inspectors discussed the likely informational content of the

inspection report with regard to documents or processes reviewed by the

inspectors during the inspection. The licensee did not identify any

documents or processes as proprietary,

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