Information Notice 1992-47, Intentional Bypassing of Automatic Actuation of Plant Protective Features

Intentional Bypassing of Automatic Actuation of Plant Protective Features
	ML031210746
Person / Time
Issue date:	06/29/1992
From:	Rossi C; Office of Nuclear Reactor Regulation
To:	;
References
	IN-92-047, NUDOCS 9206230193
	Download: ML031210746 (10)
	v • d • e

UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D.C.

20555

June 29, 1992

NRC INFORMATION NOTICE 92-47:

INTENT

IONAL BYPASSING OF AUTOMATIC

ACTUATION OF PLANT PROTECTIVE FEATURES

Addressees

All holders of operating licenses or construction permits for nuclear power

reactors.

Purpose

The U.S. Nuclear Regulatory Commission (NRC) is issuing this information

notice to alert licensees to the importance of having formal criteria and

training regarding limitations on bypassing plant protective features. It is

expected that recipients will review the information for applicability to

their facilities and consider actions, as appropriate, to avoid similar

problems. However, suggestions contained in this information notice are not

NRC requirements; therefore, no specific action or written response is

required.

Description of Circumstances

On December 8, 1991, the Florida Power Corporation's Crystal River Nuclear

Station, Unit 3, experienced a slow loss of reactor coolant system (RCS)

pressure at 10 percent power during startup, because a pressurizer spray valve

failed in a partially open position. The operators did not promptly determine

the cause of the pressure decrease, in part, because they were misled by an

erroneous spray valve closed position indication. Believing the pressure

decrease to result from an increasing steam demand, the operators subsequently

withdrew control rods several times in an attempt to maintain RCS temperature

as steam flow was increased in preparation for loading the generator.

However, the RCS pressure continued to decrease, and the reactor tripped on

low pressure. Approximately 2 minutes later, the "ES A and B Not Bypassed"

alarms annunciated. These alarms indicate that the high pressure injection

(HPI) system and other engineered safeguards (ES) functions are not blocked, although they may be blocked during normal plant cooldown. Approximately 1 minute later, a control room operator inappropriately actuated the ES bypass

switches for the A and B HPI system. Approximately 6 minutes later, when a

sufficient number of actuation logic bistables tripped to actuate the system

if it had not been bypassed, the Acting Operations Superintendent questioned

the Shift Supervisor about the advisability of bypassing the ES, and the ES

was then unbypassed at which time the high pressure injection and other

systems activated. Operators then established manual control of the high

9206230193 z2r

IN 92-47 June 29, 1992 pressure injection system to maintain RCS pressure above 1500 psig.

The

operators did not determine the cause of the decrease in RCS pressure until

after the spray line isolation valve was closed about an hour later.

Discussion

One of the significant lessons of the Three Mile Island, Unit 2, (TMI-2)

accident was that the core damage resulted from operators manually terminating

safety injection based on an inaccurate diagnosis of plant conditions.

In

1979, the NRC issued a series of Bulletins requesting licensees to review

operating procedures and training to ensure that operators do not override

automatic ESF actuation without carefully reviewing plant conditions. After

the accident at TMI-2, licensees made many enhancements to emergency operating

procedures to improve the operator's control of safety functions and

engineered safety features.

At Crystal River, the licensee's staff lacked formal guidance delineating

limitations on bypassing the automatic actuation of engineered safeguards

functions.

This lack of guidance may have contributed to having high pressure

injection bypassed with the plant in a degraded condition for approximately

6 minutes without understanding the cause of the decrease in RCS pressure.

One of the licensee's corrective actions was to develop administrative

guidance on when it is appropriate to bypass the automatic actuation of

engineered safeguards functions.

This guidance has been

incorporated into

plant procedures.-

-_

This information notice requires no specific action or written response. If

you have any questions about the information in this notice, please contact

the technical contact listed below or the appropriate Office of Nuclear

Reactor Regulation (NRR) project manager.

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical contact:

Thomas Koshy, NRR

(301) 504-1176 Attachment:

List of Recently Issued NRC Information Notices

Attachment

IN 92-47

June 29, 1992

Page 1 of I

LIST OF RECENTLY ISSUED

NRC INFORMATION NOTICES

Information

Date of

Notice No.

Subject

Issuance

Issued to

92-46

92-45

92-44

92-43 Thermo-Lag Fire Barrier

Material Special Review

Team Final Report Findings,

Current Fire Endurance

Tests, and Ampacity Cal- culation Errors

Incorrect Relay Used in

Emergency Diesel Generator

Output Breaker Control

Circuitry

Problems with Westing- house DS-206 and DSL-206

Type Circuit Breakers

Defective Molded Phen- olic Armature Carriers

Found on Elmwood Con- tactors

Fraudulent Bolts in

Seismically Designed

Walls

Consideration of the

Stem Rejection Load in

Calculation of Required

Valve Thrust

Inadequate Testing of

Emergency Bus Under- voltage Logic Circuitry

Unplanned Return to

Criticality during

Reactor Shutdown

06/23/92

06/22/92

06/18/92

06/09/92

06/01/92

05/29/92

05/27/92

05/13/92

All holders of OLs or CPs

for nuclear power reactors.

All holders of OLs or CPs

for nuclear power reactors.

All holders of OLs or CPs

for nuclear power reactors.

All holders of OLs or CPs

for nuclear power reactors.

All holders of OLs or CPs

for nuclear power reactors.

All holders of OLs or CPs

for nuclear power reactors.

All holders of OLs or CPs

for nuclear power reactors.

All holders of OLs or CPs

for nuclear power reactors.

92-42

92-41

92-40

92-39 OL = Operating License

CP = Construction Permit

IN 92-47 June 29, 1992 pressure injection system to maintain RCS pressure above 1500 psig.

The

operators did not determine the cause of the decrease in RCS pressure until

after the spray line isolation valve was closed about an hour later.

Discussion

One of the significant lessons of the Three Mile Island, Unit 2, (TMI-2)

accident was that the core damage resulted from operators manually terminating

safety injection based on an Inaccurate diagnosis of plant conditions. In

1979, the NRC issued a series of Bulletins requesting licensees to review

operating procedures and training to ensure that operators do not override

automatic ESF actuation without carefully reviewing plant conditions.

After

the accident at TMI-2, licensees made many enhancements to emergency operating

procedures to improve the operator's control of safety functions and

engineered safety features.

At Crystal River, the licensee's staff lacked formal guidance delineating

limitations on bypassing the automatic actuation of engineered safeguards

functions.

This lack of guidance may have contributed to having high pressure

injection bypassed with the plant in a degraded condition for approximately

6 minutes without understanding the cause of the decrease in RCS pressure.

One of the licensee's corrective actions was to develop administrative

guidance on when it is appropriate to bypass the automatic actuation of

engineered safeguards functions. This guidance has been

incorporated into

plant procedures.

This information notice requires no specific action or written response. If

you have any questions about the information in this notice, please contact

the technical contact listed below or the appropriate Office of Nuclear

Reactor Regulation (NRR) project manager.

Original Signed by

OZ411 E. RoWd

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical contact:

Thomas Koshy, NRR

(301) 504-1176 Attachment: List of Recently Issued NRC Information Notices

The designated personnel in the Human Factors Assessment Branch, Operator

Licensing Branch, and Reactor Systems Branch concurred in the draft attached

to the memorandum from William T. Russell to Edward L. Jordan dated

April 28, 1992.

SEE PREVIOUS CONCURRENCE

OEAB:DOEA:NRR

ADM:RPB

SC/OEAB:DOEA:NRR

C/OEAB:DOEA:NRR

TKoshy*

JMaln*

DFischer*

AChaffee*

05/20/92

05/27/92

05/20/92

05/20/92 RII

D/DSP:AEOD

C/OGCB:DOEA:NRR

D

LReyes*

TNovak*

CBerlinger*

,CC~oriP*.

05/26/92

05/28/92

'-8 Document Name: 92-47.IN

I

IN 92-XX

May xx, 1992 then established manual control of the high pressure injection system to

maintain RCS pressure above 1500 psig.

The operators did not determine the

cause of the decrease in RCS pressure until after the spray line isolation

valve was closed about an hour later.

Discussion

One of the significant lessons of the Three Mile Island, Unit 2 (TMI-2),

accident was that the core damage resulted from operators manually terminating

safety injection based on an inaccurate diagnosis of plant conditions. In

1979, the NRC issued a series of Bulletins to direct licensees to review

operating procedures and training to ensure that operators do not override

automatic ESF actuation without carefully reviewing plant conditions.

After

the accident at TMI-2, the licensees made many enhancements to emergency

operating procedures to improve the operator's control of safety functions and

engineered safety features.

At Crystal River, the licensee's staff lacked formal guidance on conditions

that permit bypassing the automatic actuation of engineered safeguards

functions.

This lack of guidance may have contributed to having high pressure

injection bypassed with the plant in a degraded condition for approximately 6 minutes without having specific procedural guidance or appropriate management

involvement.

One of the licensee's corrective actions was to develop

administrative guidance on when it is appropriate to bypass the automatic

actuation of engineered safeguards functions. This guidance has been

incorporated into plant procedures.

This information notice requires no specific action or written response. If

you have any questions about the information in this notice, please contact

the technical contact listed below or the appropriate Office of Nuclear

Reactor Regulation (NRR) project manager.

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical contact:

Thomas Koshy, NRR

(301) 504-1176 Attachment:

List of Recently Issued NRC Information Notices

The designated personnel in the Human Factors Assessment Branch, Operator

Licensing Branch, and Reactor Systems Branch concurred in the draft attached

to the memorandum from William T. Russell to Edward L. Jordan dated

April 28, 1992.

SEE PREVIOUS CONCURRENCE

OEAB:DOEA:NRR

ADM:RPB

SC/OEAB:DOEA:NRR

C/OEAB:DOEA:NRR

TKoshy*

JMain*

DFischer*

AChaffee*

05/20/92

05/27/92

05/20 92

05/20/92 RII

D/DSP:AEOD

C/ECB:

A

D/DOEA

LReyes*

TNovak*

CBerlj9nger

CRossi

05/26/92

6/ /92

/

/92 Document Name:

C:\\BYPASS1 (ATB)

r I

,

IN 92-XX

May xx, 1992 injection system to maintain RCS pressure above 1500 psig.

decrease in RCS pressure remained unknown to the operators

spray line isolation valve was closed about an hour later.

The cause of the

until after the

Discussion

One of the significant lessons of the Three Mile Island, Unit 2, accident was

that the core damage was a result of operators manually terminating safety

injection based on an inaccurate diagnosis of existing plant conditions. A

series of NRC Bulletins was issued in 1979, that directed licensees, in

general, to review operating procedures and training to ensure that operators

do not override automatic ESF actuation without careful review of plant

conditions. Many post-TMI enhancements were made to emergency operating

procedures to improve operator control of safety functions and engineered

safety features.

At Crystal River, the licensee's staff lacked formal guidance on conditions

that permit bypassing automatic actuation of engineered safeguards functions.

This lack of guidance may have contributed to having high pressure injection

bypassed with the plant in a degraded condition for approximately six minutes

without having specific procedural guidance or appropriate management

involvement.

One of the licensee's corrective actions was to develop

administrative guidance on when it is appropriate to bypass automatic

actuation of engineered safeguards functions. This guidance has been, or will

be, incorporated into plant procedures as appropriate.

This information notice requires no specific action or written response. If

you have any questions about the information in this notice, please contact

the technical contact listed below or the appropriate Office of Nuclear

Reactor Regulation (NRR) project manager.

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical contact:

Thomas Koshy, NRR

(301) 504-1176 Attachment:

List of Recently Issued NRC Information Notices

The designated personnel in the Human Factors Assessment Branch, Operator

Licensing Branch, and Reactor Systems Branch concurred in the draft attached

to the memorandum from William T. Russell to Edward L. Jordan dated

April 28, 1992.

t C.t

SEE PREVIOUS CONCURRENCE

OEAB:DOEA:NRR

ADM:RPB

TKoshy*

JMain q

O

,

5/27/92 D/DSP:AEOD

C/OGCB:DG

TNovak

CBerlinge

5/x6 /92

/

/92 SC/OEAB:DOEA:NRR

DFischer*

05/20/92 C/OEAB:DOEA:NRR

AChaffee*

05/20/92 RII

LReyes

5/2L/92 EA:NRR

er

D/DOEA

CRossi

/

/92 Document Name:

C:\\BYPASS1 (ATB)

I

-

IN 92-XX

May xx, 1992 injection system to maintain RCS pressure above 1500 psig. The cause of the

decrease in RCS pressure remained unknown to the operators until after the