Information Notice 1996-65, Undetected Accumulation of Gas in Reactor Coolant System and Inaccurate Reactor Water Level Indication During Shutdown

Undetected Accumulation of Gas in Reactor Coolant System and Inaccurate Reactor Water Level Indication During Shutdown

ML031050500
Person / Time
Site:	Beaver Valley, Millstone, Hatch, Monticello, Calvert Cliffs, Dresden, Davis Besse, Peach Bottom, Browns Ferry, Salem, Oconee, Mcguire, Nine Mile Point, Palisades, Palo Verde, Perry, Indian Point, Fermi, Kewaunee, Catawba, Harris, Wolf Creek, Saint Lucie, Point Beach, Oyster Creek, Watts Bar, Hope Creek, Grand Gulf, Cooper, Sequoyah, Byron, Pilgrim, Arkansas Nuclear, Braidwood, Susquehanna, Summer, Prairie Island, Columbia, Seabrook, Brunswick, Surry, Limerick, North Anna, Turkey Point, River Bend, Vermont Yankee, Crystal River, Haddam Neck, Ginna, Diablo Canyon, Callaway, Vogtle, Waterford, Duane Arnold, Farley, Robinson, Clinton, South Texas, San Onofre, Cook, Comanche Peak, Yankee Rowe, Maine Yankee, Quad Cities, Humboldt Bay, La Crosse, Big Rock Point, Rancho Seco, Zion, Midland, Bellefonte, Fort Calhoun, FitzPatrick, McGuire, LaSalle, Fort Saint Vrain, Shoreham, Satsop, Trojan, Atlantic Nuclear Power Plant, Crane
Issue date:	12/11/1996
From:	Martin T Office of Nuclear Reactor Regulation
To:
References
IN-96-065, NUDOCS 9612060224
Download: ML031050500 (18)

UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D.C. 20555-0001

December 11, 1996

NRC INFORMATION NOTICE 96-65: UNDETECTED ACCUMULATION OF GAS IN

REACTOR COOLANT SYSTEM AND INACCURATE

REACTOR WATER LEVEL INDICATION DURING

SHUTDOWN

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

addressees to ongoing issues related to an undetected loss of reactor coolant inventory at

Haddam Neck caused by an accumulation of nitrogen in the reactor coolant system. 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.

Background

Information Notice (IN) 94-36, "Undetected Accumulation of Gas in Reactor Coolant System,"

issued on May 24, 1994, discussed an event at the Sequoyah Nuclear Power Plant in

September 1993 where gas accumulated in the reactor coolant system (RCS). The gas

accumulated because the temperature in the volume control tank was much lower than

normally expected. .(This lower temperature resulted from unusually low component cooling

water temperatures and from a maintenance problem with a cooling water valve that reduced

the heat sink temperature in the letdown heat exchanger.) The lower temperatures increased

the solubility of gas in the volume control tank water so that there was more dissolved gas in

the water. When the water was transferred to the RCS by the charging system and heated

up in the reactor vessel, the gas came out of solution and collected in the RCS. This

information notice also discussed a similar issue which occurred at the Salem Nuclear

Generating Station on April 12, 1994.

IN 96-37, "Inaccurate Reactor Water Level Indication and Inadvertent Draindown During

Shutdown," issued on June 18, 1996, discussed an event which occurred on September 13,

1995, at Surry Unit 1. The plant was in cold shutdown and depressurized. Operators had

closed the reactor head vent to install the reactor vessel cavity seal ring. After the seal ring

was in place, the reactor head vent was not reopened. This resulted in a loss of function of

the only reactor vessel water level indication. As pressurizer relief tank nitrogen pressure

was gradually being reduced, an operator saw the standpipe indicated level increase as the

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IN 96-65 December 11, 1996 gas bubble trapped in the reactor vessel head expanded, forcing water out of the reactor and

up the surge line and standpipe. Unaware of the closed head vent and believing the

standpipe level indication, the operator increased letdown from the reactor coolant system

cold leg piping to maintain indicated level. This effectively reduced the inventory In the RCS

by approximately 17.0 cubic meters [4500 gallons] over a period of 5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />.

Description of Circumstances

The reactor at Haddam Neck was in cold shutdown and decay heat was being removed by

the residual heat removal (RHR) system using the "A' RHR pump. The RCS was

depressurized and a temporary primary vent header was connected to the reactor vessel

head. The volume control tank was being maintained at a pressure of 310 kPa [30 psig].

rhe RCS loop stop valves had been closed to Isolate the reactor vessel from the steam

generators. The Technical Specification required boration flow path was from the boric acid

metering tank, through the chemical and volume control system metering pump, and into the

RCS. The reactor vessel level indication system (RVLIS) and core exit thermocouples were

disconnected in preparation for removal of the reactor vessel head. The operators were

using pressurizer level indication and cavity level indication to monitor reactor vessel level

(see Attachment 1).

On August 28, 1996, the metering pump was to be declared inoperable because of an

upcoming surveillance test on the emergency power supply for the pump, requiring the

alignment of a different boric acid flow path. During the alignment, the operator opened both

valve BA-V-354 (blended makeup to the volume control tank) and BA-V-355 (blended

makeup to the charging pump suction). It appears that following this operation the operator

may have failed to fully seat one isolation valve (BA-V-355) between the top of the volume

control tank (nitrogen gas space) and the RCS (see Attachment 2). Note: the procedure in

use during the alignment did not allow valve BA-V-355 and BA-V-354 to be open at the same

time. This allowed nitrogen from the volume control tank to leak from the volume control

tank, through several closed, leaking valves in the chemical and volume control system, and

into the reactor vessel. The installed vent system was unable to vent off nitrogen as fast as

the nitrogen was being added to the reactor vessel and a nitrogen bubble accumulated in the

vessel head region. As the nitrogen gas displaced water from the reactor vessel Into the

pressurizer, the water level in the reactor vessel decreased and the water level in the

pressurizer increased.

The pressurizer level instrumentation erroneously indicated that the reactor vessel was full of

water. Pressurizer level slowly increased because of the displacement of water from the

reactor vessel by nitrogen gas. The operators believed that the level increase was caused by

water leaking into the RCS through the loop stop valves. The operators tightened the valves

to stop the leakage. Water continued to be displaced from the reactor vessel by the growing

nitrogen bubble. However, this was masked by the operators removing RCS inventory to

remove the reactor vessel conoseals. For approximately four days, control room operators

were unaware that nitrogen gas was leaking into the reactor vessel and causing the level in

the reactor vessel to decrease.

-

1

IN 96-65 December 11, 1996 On September 1, 1996, the nitrogen gas supply to the volume control tank was isolated in an

attempt to identify the source of the relatively high nitrogen usage. The isolation of the

nitrogen gas stopped the nitrogen leakage into the RCS. The vent header system capacity

now exceeded the rate of gas intrusion and the vent began to release the nitrogen which had

accumulated in the reactor vessel. The volume of nitrogen being removed from the reactor

vessel was replaced by the water in the pressurizer. The pressurizer level rapidly decreased

until the level indication decreased off scale (low). Six additions of water to the RCS,

totalling approximately 18.9 cubic meters (5000 gallons), were required to stabilize

pressurizer level within the normal range.

Discussion

The event at Haddam Neck revealed a number of weaknesses. However, there are three

issues which the NRC has determined warrant particular notice. These issues are:

(1) Inaccurate reactor vessel level instrumentation; (2) Inadequate reactor coolant inventory

balance; and (3) Non-condensible gas intrusion into the RCS. These issues are discussed

below. An NRC augmented inspection team evaluated this event and reported its findings in

NRC Inspection Report 50-213196-80.

Inaccurate Reactor Vessel Level Instrumentation

Lack of accurate reactor vessel level instrumentation and lack of adequate inventory

balances while shutdown are issues of generic concem. The NRC has issued several

generic communications on the issue: these are listed in the "Related Generic

Communications" section. These generic communications discuss numerous events where

safety-related equipment operability was challenged because of inaccurate level

instrumentation.

At Haddam Neck, the absence of direct reactor vessel monitoring instrumentation had an

adverse affect on the operators' ability to monitor reactor vessel conditions. The available

level instruments (pressurizer level and cavity level) did not provide a direct indication of

reactor vessel level, The level instrumentation measured actual level in the pressurizer which

the operators believed was representative of reactor vessel level because the pressurizer air

space was vented to the same vent header as the reactor vessel head (see Attachment 1).

During this event, pressurizer level indication and cavity level indication -were not

representative of actual reactor vessel level because of a difference in pressure between the

reactor vessel head and the pressurizer air space. The difference in pressure was caused by

the inability of the installed reactor vessel head vent system to remove nitrogen gas as fast

as it was being introduced into the RCS.

RVLIS, which does provide a direct reactor vessel level indication, was disconnected in

preparation for refueling maintenance activities. The core exit thermocouples are another

direct indication of reactor vessel conditions. The core exit thermocouples were also

disconnected during the duration of this event.

The RVLIS indicates reactor vessel level at discrete elevations. During this event, the RVLIS

would have indicated abnormal reactor vessel level when the actual level dropped below the

K>

IN 96-65 December 11, 1996 reactor vessel flange. Following this event, local RVLIS readings were collected and a

temporary jumper was purchased and installed to provide RVLIS indications in the control

room. A second jumper was installed to provide core exit thermocouple indication in the

control room.

Inadequate Reactor Coolant Inventory Balance

The licensee had not maintained an RCS inventory balance to account for the transfer of

water into and out of the RCS. No detailed procedural guidance existed which required an

inventory balance for draindown operations. The operators compensated for a lack of

detailed procedural guidance by writing instructions in accordance with administrative control

procedure 1.2-5.3, "Evaluation of ActivitiesXEvolutions Not Controlled by Procedure." The

instructions written in accordance with administrative control procedure 1.2-5.3 do not require

the same level of review and approval that other plant procedures receive. The guidance

written for the RCS draindown did not require RCS inventory balances or specify reference

levels.

On August 29, 1996, plant management made the decision to suspend refueling activities

over the weekend. The operators were directed to and did refill the RCS. However, where

5000 gallons had been removed from the RCS earlier, only 1000 gallons were added to the

RCS to reach essentially the same indicated level. (The resulting 8-inch difference in P2, level indication between before and after only represented 500 gallons of the inventory

difference not the 4000 gallons which existed.)

The magnitude of the apparent RCS inventory discrepancy was not explained to operations

management nor did the operators solicit engineering and technical support to assist in

resolving this discrepancy. The licensee had experienced leakage of the loop stop valves

during past outages, however, an inventory balance may have alerted the operators to the

actual magnitude of the inventory discrepancy, and may have caused the operators to

question their initial conclusion that the increase in pressurizer level was caused by leaking

stop valves.

Non-Condensible Gas Intrusion into the RCS

Gas intrusion into the RCS and safety-related cooling system piping is an issue of generic

concem. The NRC has issued several generic communications on the issue: these are

listed in the "Related Generic Communications" section. These generic communications

discuss numerous events where safety-related equipment was potentially rendered

inoperable because of gas intrusion. The generic communications discuss the various

processes by which non-condensible gases have accumulated unknown to the reactor

operators in the RCS and safety-related cooling system piping. The event at Haddam Neck

illustrates that gas intrusion events continue to occur in spite of the operational experience

available to the industry.

At Haddam Neck, nitrogen intrusion into the RCS could potentially result in gas binding and

common mode failure of the decay heat removal pumps and the charging pumps. In

IN 96-65 December 11, 1996 addition, nitrogen present in the RCS could potentially interfere with the ability of the steam

generators to remove heat from the RCS via natural circulation cooling. The significance of

the loss of the charging pumps at Haddam Neck is that a method of injecting water into the

reactor vessel would be lost and that the charging pumps are needed to fill the RCS before

opening the loop stop valves. The loop stop valves would need to be opened to allow the

RCS to communicate with the steam generators, a condition necessary for the steam

generators to remove heat from the RCS via natural circulation. In addition, the volume of

the RCS increases significantly with the loop stop valves open, thus providing a larger

passive heat sink which would slow the heating of the RCS.

At Haddam Neck the overpressure in the volume control tank was purposely maintained by

the licensee as an independent source of motive force to inject water into the RCS in the

event of a loss of other injection methods. The potential hazard of this condition is that

nitrogen may Intrude into the RCS if valves relied upon to isolate the volume control tank

from the RCS either leak or are not properly controlled.

During the event, the operators attempted to start the "B" RHR pump, however, it was found

to be seized. The licensee believes that the seizure occurred at the end of the last

surveillance test and was not related to the gas intrusion event. The operators were unaware

that the "B" RHR had seized following its last operation on August 19, 1996. After the event, the licensee determined that the "B" RHR pump was inoperable throughout the event. The

failure of the "B" RHR pump added to the significance of this event. If the "A" pump was

damaged, the RHR system would not be available to remove decay heat. A mitigating

condition at Haddam Neck is that two trains of the low pressure injection system were

available.

The abnormal operating procedure for a loss of RHR requires that a cavitating RHR pump be

secured and vented. However, the location of the RHR pump vents is not optimal and

significant difficulty was encountered during venting the "B" RHR pump following maintenance

to address its seizure. Therefore, an effective venting of a RHR pump may not have been

easy to achieve during an event if a pump had become gas bound.

Related Generic Communications

Information Notice 88-23, "Potential for Gas Binding of High-Pressure Safety Injection Pumps

During a Loss-of-Coolant Accident," May 12, 1988.

Information Notice 88-23, Supplement 1, "Potential for Gas Binding of High-Pressure Safety

Injection Pumps During a Loss-of-Coolant Accident," January 5, 1989.

Information Notice 89-67, "Loss of Residual Heat Removal Caused by Accumulator Nitrogen

Injection," September 13, 1989.

Information Notice 88-23, Supplement 2, "Potential for Gas Binding of High-Pressure Safety

Injection Pumps During a Loss-of-Coolant Accident," January 31, 1990.

K-/

IN 96-65 December 11, 1996 Information Notice 90-64, "Potential for Common-Mode Failure of High Pressure Safety

Injection Pumps or Release of Reactor Coolant Outside Containment During a Loss-of- Coolant Accident," October 4, 1990.

Information Notice 88-23, Supplement 3, "Potential for Gas Binding of High-Pressure Safety

Injection Pumps During a Loss-of-Coolant Accident," December 30, 1990.

Information Notice 88-23, Supplement 4, "Potential for Gas Binding of High-Pressure Safety

Injection Pumps During a Loss-of-Coolant Accident," December 18, 1992.

Information Notice 90-55, Recent Operating Experience on Loss of Reactor Coolant Inventory

While in a Shutdown Condition," August 31, 1990.

Information Notice 93-93, "Inadequate Control of Reactor Coolant System Conditions During

Shutdown," December 8, 1993.

Information Notice 94-36, "Undetected Accumulation of Gas in Reactor Coolant System,"

May 24, 1994.

Information Notice 95-03, "Loss of Reactor Coolant Inventory and Potential Loss of

Emergency Mitigation Functions While in a Shutdown Condition,"

January 18, 1995.

Information Notice 96-37, "Inaccurate Reactor Water Level Indication and Inadvertent

Draindown During Shutdown," June 18, 1996.

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

questions about the information in this notice, please contact one of the technical contacts

listed below or the appropriate Office of Nuclear Reactor Regulation (NRR) project manager.

Thomas T. Martin, Director

Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical contacts: Eric J. Benner, NRR

Warren C. Lyon, NRR

(301) 415-1171

(301) 415-2947 E-mail: ejb@nrc.gov

E-mail: wcl@nrc.gov

Attachments:

1. The Undetected Nitrogen Gas Introduction

into the Reactor Vessel from the Charging Line

2. Chemical and Volume Control System

3. List of Recently Issued NRC Information Notices

(1 l

4 [le} u

IN 96-65 KY

t)

December 11, 1996 Information Notice 90-64, "Potential for Common-Mode Failure of High Pressure Safety

Injection Pumps or Release of Reactor Coolant Outside Containment During a Loss-of- Coolant Accident," October 4, 1990.

Information Notice 88-23, Supplement 3, "Potential for Gas Binding of High-Pressure Safety

Injection Pumps During a Loss-of-Coolant Accident," December 30, 1990.

Information Notice 88-23, Supplement 4, "Potential for Gas Binding of High-Pressure Safety

Injection Pumps During a Loss-of-Coolant Accident," December 18, 1992.

Information Notice 90-55, Recent Operating Experience on Loss of Reactor Coolant Inventory

While in a Shutdown Condition," August 31, 1990.

Information Notice 93-93, "Inadequate Control of Reactor Coolant System Conditions During

Shutdown," December 8, 1993.

Information Notice 94-36, "Undetected Accumulation of Gas in Reactor Coolant System,"

May 24, 1994.

Information Notice 95-03, "Loss of Reactor Coolant Inventory and Potential Loss of

Emergency Mitigation Functions While in a Shutdown Condition,"

January 18, 1995.

Information Notice 96-37, "Inaccurate Reactor Water Level Indication and Inadvertent

Draindown During Shutdown," June 18, 1996.

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

questions about the information in this notice, please contact one of the technical contacts

listed below or the appropriate Office of Nuclear Reactor Regulation (NRR) project manager.

original signed by D. B. Matthews

,4Yomas T. Martin, Director

7

~Division of Reactor Program Management

I

Office of Nuclear Reactor Regulation

Technical contacts: Eric J. Benner, NRR

Warren C. Lyon, NRR

(301) 415-1171

(301) 415-2947 E-mail: ejbenrc.gov

E-mail: wcl@nrc.gov

Tech Editor has reviewed and concurred on 10/22/96 Attachments:

1. The Undetected Nitrogen Gas Introduction

into the Reactor Vessel from the Charging Line

2. Chemical and Volume Control System

3. List of Recently Issued NRC Information Notices

DOCUMENT NAME: G:%EJBlHAD GAS.IN *SEE PREVIOUS CONCURRENC l

OFC

Contacts

(A)BC/SRXB:

BC/PECB:DRPM

D/D

NAME

EBenner*

TCollins*

AChaffee*

TMa\\/n

l_

_

WLyon*

DATE

10/30/96

11/05/96

11/25/96 E ,1,96

10/30/96 OFFICIAL RECO)RD COPY

IN 96-XX

.

)

November X, 1996 Information Notice 90-64, "Potential for Common-Mode Failure of High Pressure Safety

Injection Pumps or Release of Reactor Coolant Outside Containment During a Loss-of- Coolant Accident," October 4, 1990.

Information Notice 88-23, Supplement 3, "Potential for Gas Binding of High-Pressure

fety

Injection Pumps During a Loss-of-Coolant Accident," December 30, 1990.

Information Notice 88-23, Supplement 4, "Potential for Gas Binding of High-P rsure Safety

Injection Pumps During a Loss-of-Coolant Accident," December 18, 1992.

Information Notice 90-55, Recent Operating Experience on Loss of Rea or Coolant Inventory

While in a Shutdown Condition," August 31, 1990.

Information Notice 93-93, "Inadequate Control of Reactor Coolan

ystem Conditions During

Shutdown," December 8, 1993.

Information Notice 94-36, "Undetected Accumulation of Gabin Reactor Coolant System,"

May 24, 1994.

Information Notice 95-03, "Loss of Reactor Coolant I entory and Potential Loss of

Emergency Mitigation Functions While in a Shutdo n Condition,"

January 18, 1995.

Information Notice 96-37, "Inaccurate Reacto

ater Level Indication and Inadvertent

Draindown During Shutdown," June 18, 19 This information notice requires no spe ic action or written response. If you have any

questions about the information in this otice, please contact one of the technical contacts

listed below or the appropriate Offi of Nuclear Reactor Regulation (NRR) project manager.

Thomas T. Martin, Director

Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical contacts: Eric

. Benner, NRR

Warren C. Lyon, NRR

(30

415-1171

(301) 415-2947 E- ail: ejbenrc.gov

E-mail: wclInrc.gov

Attachments:

1. The Undetecte Nitrogen Gas Introduction

into the Rea or Vessel from the Charging Line

2. Chemical a

Volume Control System

3. List of Recently Issued NRC Information Notices

DOCUMENT NAME: G:XEJB1%HADGAS.lN *SEE PREVIOUS CONCURRENCE

OFC

Contacts

(A)BC/SRXB:

BC/PECB:DRPM

D/D

NAME

EBenner*

TCollins*

AChaffee*

TMaW \\

WLyon*_

DATE

10/30/96

11/05/96

11/25/96

11f96

10/30/96

OFFICIAL RECORD COPY

IN c - KX

No~ber X, 1996 Information Notice 90-64, "Potential for Common-Mode Failure of High Pressure

ty

Injection Pumps or Release of Reactor Coolant Outside Containment During a

ss-of- Coolant Accident," October 4, 1990.

Information Notice 88-23, Supplement 3, "Potential for Gas Binding of

gh-Pressure Safety

Injection Pumps During a Loss-of-Coolant Accident," December 30,

90.

Information Notice 88-23, Supplement 4, "Potential for Gas Bing of High-Pressure Safety

Injection Pumps During a Loss-of-Coolant Accident," Decem

r 18,1992.

Information Notice 90-55, Recent Operating Expenien

n Loss of Reactor Coolant Inventory

While in a Shutdown Condition," August 31, 1990.

Information Notice 93-93, "Inadequate Control o

eactor Coolant System Conditions During

Shutdown," December 8, 1993.

Information Notice 94-36, "Undetected A umulation of Gas in Reactor Coolant System,"

May 24, 1994.

Information Notice 95-03, "Loss of eactor Coolant Inventory and Potential Loss of

Emergency Mitigation Functions

ile in a Shutdown Condition,"

January 18, 1995.

Information Notice 96-37, "I ccurate Reactor Water Level Indication and Inadvertent

Draindown During Shutdo n," June 18, 1996.

This information notirequires no specific action or written response. If you have any

questions about the

formation in this notice, please contact one of the technical contacts

listed below or the

ppropriate Office of Nuclear Reactor Regulation (NRR) project manager.

Thomas T. Martin, Director

Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Techni

contacts: Eric J. Benner, NRR

Warren C. Lyon, NRR

(301) 415-1171

(301) 415-2947 E-mail: ejb@nrc.gov

E-mail: wcl@nrc.gov

Aft chments:

1. The Undetected Nitrogen Gas Introduction into the Reactor Vessel from the

Charging Line

2. Chemical and Volume Control System

3. List of Recently Issued NRC Information Notices

DOCUMENT NAME: G:\\EJBlHAD GAS.IN *SEE PREVIOUS CONCURRENCE

OFC

Contacts

(A)BC/SRXB:

BCIPECB:DRPM

DIDRPM

NAM

EBenner*

TCollins*

AChaffee A

TMartin

E

WLyon*

___

_

DATE

10/30/96 1 5p

11/05/96 ii 66i6

/96

10/30/96

OFFICIAL RECORD COPY

IN 96-XX

November X. 1996 This information notice requires no specific action or written response. If

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

one of the technical contacts listed below or the appropriate Office of

Nuclear Reactor Regulation (NRR) project manager.

Thomas T. Martin, Direct

Division of Reactor Pr ram Management

Office of Nuclear Re tor Regulation

Technical contacts:

Eric J. Benner. NRR

(301) 415-1171 E-mail: ejb@nrc.gov

Warren C. Lyon. NRR

(301) 415-2947 E-mail: wcl@nrc.gov

Attachments:

1. The Undetected Nitrogen Gas Introdution into the Reactor Vessel from the

Charging Line

2. Chemical and Volume Control Syst

3.

List of Recently Issued NRC Inf rmation Notices

N NA)M P

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-

XX, r

DOCUMENT NAME:ARA.

• SEE PREVIOUS CONCURRCE

OFC

Co qacts

(A)BC/SRXB:

BC/PECB:DRPM

D/DRPM

NAME

enner*

TCollins*

AChaffee

TMartin

Lyon*

DATE

10/30/96

11/05/96

/ /96

/ /96

10/30/96

OFFICIAL RE CORD COPY

I

'

XI<K

IN 96-61 November 7. 1996 Information Notice 90-55, Recent Operating Experience on Loss of Reactor

Coolant Inventory While in a Shutdown Condition," August 31, 1990.

Information Notice 93-93, "Inadequate Control of Reactor Coolant System

Conditions During Shutdown." December 8, 1993.

Information Notice 94-36. "Undetected Accumulation of Gas in Reactor Coolant

System." May 24, 1994.

Information Notice 95-03. "Loss of Reactor Coolant Inventory and Potential

Loss of Emergency Mitigation Functions While in a Shutdown Condition."

January 18. 1995.

Information Notice 96-37. "Inaccurate Reactor Water Level Indication and

Inadvertent Draindown During Shutdown." June 18. 1996.

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

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

one of the technical contacts listed below or the appropriate Office of

Nuclear Reactor Regulation (NRR) project manager.

Thomas T. Martin, Director

Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical contacts:

Eric J. Benner, NRR

(301) 415-1171 E-mail: ejb@nrc.gov

Warren C. Lyon, NRR

(301) 415-2947 E-mail: wcl@nrc.gov

Attachments:

1. Figure 1:

Chemical and Volume Control System

2. List of Recently Issued NRC Information Notices

DOCUMENT NAME: G:\\EJB1\\HAD GAS.IN *SEE PREVIOUS CONCURRENCE

OFC

Contacts

(A)BC/SRXB:

BC/PECB:DRPM

D/DRPM

NAME

EBenner*

TCollins*

AChaffee >-

TMartin

WLyon*_

_

_

DATE

10/30/96

11/05/96 It / 1/96

/ /96

10/30/96

OFFICIAL RECORD COPY

-

IN 96-61

November 7. 1996

Information Notice 90-55, Recent Operating Experience on

Coolant Inventory While in a Shutdown Condition," August

Loss of Reactor

31. 1990.

Information Notice 93-93, "Inadequate Control of Reactor Coolant System

Conditions During Shutdown," December 8. 1993.

Information Notice 94-36. "Undetected Accumulation of Gas in Reactor Coolant

System," May 24. 1994.

Information Notice 95-03, "Loss of Reactor Coolant Inventory and Potential

Loss of Emergency Mitigation Functions While in a Shutdown Condition,"

January 18. 1995.

Information Notice 96-37, "Inaccurate Reactor Water Level Indication and

Inadvertent Draindown During Shutdown." June 18. 1996.

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

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

one of the technical contacts listed below or the appropriate Office of

Nuclear Reactor Regulation (NRR) project manager.

Thomas T. Martin, Director

Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical contacts:

Eric J. Benner, NRR

(301) 415-1171 E-mail: ejb@nrc.gov

Warren C. Lyon. NRR

(301) 415-2947 E-mail: wcl@nrc.gov

Attachments:

1. Figure 1:

Chemical and

2. List of Recently Issued

Volume Control System

NRC Information Notices

DOCUMENT NAME: G:\\EJB1\\HAD GAS.IN *SEE PREVIOUS CONCURRENCE

OFC

Contacts

(A)BC/SRXB:

BC/PECB:DRPM

D/DRPM

NAME

EBenner*

TCollins*

AChaffee

TMartin

WLyon*

V-,

DATE

10/30/96

11/05/96 Il/(a/96

/ /96

10/30/96 l

OFFICIAL RECORD COPY

INVi-xx

November XX, 1996

Information Notice 90-55, Recent Operating Experience on

Coolant Inventory While in a Shutdown Condition," August

Information Notice 93-93, "Inadequate Control of Reactor

Conditions During Shutdown," December 8, 1993.

Loss of Reactor

31, 1990.

Coolant System

Information Notice 94-36, "Undetected Accumulation of Gas in Reactor Coolant

System," May 24, 1994.

Information Notice 95-03, "Loss of Reactor Coolant Inventory and Potential

Loss of Emergency Mitigation Functions While in a Shutdown Condition,"

January 18, 1995.

Information Notice 96-37, "Inaccurate Reactor Water Level Indication and

Inadvertent Draindown During Shutdown," June 18, 1996.

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

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

one of the technical contacts listed below or the appropriate Office of

Nuclear Reactor Regulation (NRR) project manager.

Thomas T. Martin, Director

Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical contact(s):

Eric J. Benner, NRR

(301) 415-1171 E-mail: ejb@nrc.gov

Warren C. Lyon, NRR

(301) 415-2947 E-mail: wcl@nrc.gov

Attachments:

1. Figure 1:

Chemical and Volume Control System

2. List of Recently Issued NRC Information Notices

DOCUMENT NAME: G:\\EJB1\\HADGAS.IN

• SEE PREVIOUS CONCURRENCE

OFC

Contacts

(A)BC/SRXB:

BC/PECB:DRPM

D/DRPM

NAME

EBenner*

TCollins*

AChaffee

TMartin

WLyon*

DATE

10/30/96

11/05/96

/ /96

/ /96

10/30/96

OFFICIAL RECORD COPY

IN 94-36, Supp. 1 November XX, 1996 Information Notice 88-23, Supplement 1. "Potential for Gas Binding of High- Pressure Safety Injection Pumps During a Loss-of-Coolant Accident,"

January 5. 1989.

Information Notice 89-67. "Loss of

Nitrogen Injection." September 13, Information Notice 88-23, Supplemer

Pressure Safety Injection Pumps Dut

January 31, 1990.

Residual Heat Removal Caused by Accumulator

1989.

it 2, "Potential for Gas Binding of High-

,ing a Loss-of-Coolant Accident,"

Information Notice 90-64, "Potential for Common-Mode Failure of High Pressure

Safety Injection Pumps or Release of Reactor Coolant Outside Containment

During a Loss-of-Coolant Accident," October 4, 1990.

Information Notice 88-23.

Pressure Safety Injection

December 30. 1990.

Information Notice 88-23.

Pressure Safety Injection

December 18, 1992.

Supplement 3. "Potential for Gas Binding of High- Pumps During a Loss-of-Coolant Accident,"

Supplement 4. "Potential for Gas Binding of High- Pumps During a Loss-of-Coolant Accident,"

Information Notice 93-93, "Inadequate Control of Reactor Coolant System

Conditions During Shutdown," December 8. 1993.

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

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

one of the technical contacts listed below or the appropriate Office of

Nuclear Reactor Regulation (NRR) project manager.

Thomas T. Martin, Director

Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical contact(s):

Eric J. Benner, NRR

(301) 415-1171 E-mail: ejb@nrc.gov

Warren C. Lyon, NRR

(301) 415-2947 E-mail: wcl@nrc.gov

Attachments:

1. Figure 1:

Chemical and Volume Control System

2. List of Recently Issued NRC Information Notices

DUCUMLNI NAML: b:\\LJBi\\MAV UAb.1N

-Ztt FKtVIUUZ LUiNUKKMUL

OFC

Contacts

(A)BC/SRXB:

BC/PECB:DRPM

D/DRPM

NAME

EBenner*

TCollins*

AChaffee

TMartin

WLyon*

DATE

10/30/96

11/05/96

/ /96

,

/ /96

110/30/96 a-

[OFFICIAL RECORD COPY

IN 94-36. Supp. 1 November XX, 1996 Information Notice 89-67, "Loss of Residual Heat Removal Caused

Nitrogen Injection," issued September 13. 1989.

Information Notice 88-23, Supplement 2, "Potential for Gas

Pressure Safety Injection Pumps During a Loss-of-Coolant

January 31, 1990.

i dei

by Accumulator

'7 ing of High- it," issued

Information Notice 90-64. "Potential for Common-Mod Tailure of High Pressu

Safety Injection Pumps or Release of Reactor Coolayt Outside Containment

During a Loss-of-Coolant Accident." issued Octob

4. 1990.

Information Notice 88-23. Supplement 3. "Pote ial for Gas Binding of High- Pressure Safety Injection Pumps During a Lo -of-Coolant Accident," issued

re

December 30. 1990.

Information Notice 88-23,

Pressure Safety Injection

December 18, 1992.

Supplement

Pumps Durii

/"Potential for Gas Binding of High- a Loss-of-Coolant Accident," issued

Information Notice 93-93. "Inade 4ate Control of Reactor Coolant System

Conditions During Shutdown," i ued December 8. 1993.

This information notice req res no specific action or written response. If

you have any questions abo

the information in this notice, please contact

one of the technical con cts listed below or the appropriate Office of

Nuclear Reactor Regulaton (NRR) project manager.

Thomas T. Martin, Director

Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical

): Eric J. Benner, NRR

(301) 415-1171 Internet: ejbl@nrc.gov

Warren C. Lyon, NRR

(301) 415-2947 Internet: wcl@nrc.gov

Tech ditor

At chment:

reviewed and concurred on October 18, 1996.

List of Recently Issued NRC Information Notices

Contacts

BC/SRXB:DSSA T0

BC/PECB:DRPM

D/DRPM

NAME

EBennerrtr6

4X

AChaffee

TMartin

WLyon /0/lX, 'z: zgt,_4ll

DATE

On) I

6"I

/'I/

/96

/ /96

____

1

7t

/l%9

/ f9

[OFIIA

ECOR

COY]

DOCUMENT NAME: G:\\EJB1\\HAD GAS.IN

THE UNDETECTED NITROGEN GAS INTRODUCTION INTO

THE REACTOR VESSEL FROM THE CHARGING LINE

Steam

Vent Header

generator

Pressuriier

Pressurizer

(

Vent

Temporary

Hose

ri

r-

~691' EL

Ha

Pressurizer

Vent

Air

(gg

Level

-

Head Full 355" EL-12%

Water .

301- EL

351 EL Top of He(d

.!:

Cavty

/_

1°

_\\\\Reactor

Vaevve

,: 2330 EL

Indicatore

.

Ntogn.

1 9Fae

270" EL

>(^i\\

HotLeg

Gas

aDbl

o; l

lrre

LOOb1°P

Wate

Lin

Reacor

Cold LegCl

10" Pressurizer

10" RHR

Coolant

Surge

(Lin

Suction Line

I

Pup(Loop

4)

(Loop 1)

a CY%

Loop #4 EL1R9(-

I

El. 185"

-

j 27112"

EL 172"

-/

Reactor

Hoke

lo

1j

aU

t

a

inftO

Reactor

l i n t

O f t D l ? * -

CHEMICAL & VOLUME CONTROL SYSTEM

NITROGEN GAS LEAK PATH FROM VOLUME

CONTROL TANK TO THE RCS

To RCS

Loop #2 Cold Leg

Volume Control

Tank

(

Valve Closed -

Leaking By

Borde

Acid

Blender

c

Oi CD =

COC)

(D CD O

C

3 cn c

-or

I1:

CD CM =

o

i en C

_&

-

-

r

to

Dn

KJ

Attachment 3

IN 96-65

December 11, 1996 LIST OF RECENTLY ISSUED

NRC INFORMATION NOTICES

Information

Date of

Notice No.

Subject

Issuance

Issued to

96-64

96-63

96-62

96-61

96-60

96-59 Modifications to Con- tainment Blowout Panels

Without Appropriate

Design Controls

Potential Safety Issue

Regarding the Shipment

of Fissile Material

Potential Failure of the

Instantaneous Trip Function

of General Electric RMS-9 Programmers

Failure of a Main Steam Safety

Valve to Reseat Caused by an

Improperly Installed Release

Nut

Potential Common-Mode Post-

Accident Failure of Residual

Heat Removal Heat Exchangers

Potential Degradation of

Post Loss-of-Coolant

Recirculation Capability

as a Result of Debris

RCP Seal Replacement with

Pump on Backseat

12/10/96

12/05/96

11/20/96

11/20/96

11/14/96

10/30/96

10/30/96

All holders of OLs

or CPs for nuclear

reactors

All U.S. Nuclear

Regulatory Commission

licensees authorized

to possess special

nuclear material in

unsealed quantities

greater than a critical

mass

All holders of OLs

and CPs for nuclear

power plants

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 pressurized-water

reactors

96-58 OL = Operating License

CP = Construction Permit