Information Notice 1996-65, Undetected Accumulation of Gas in Reactor Coolant System and Inaccurate Reactor Water Level Indication During Shutdown
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 Inthe 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 itwas 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 4l [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
10/30/96
11/05/96 11/25/96 E ,1,96 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)MP -XCC \ - 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 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* 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 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 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
IN94-36, 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 Residual Heat Removal Caused by Accumulator
Nitrogen Injection." September 13, 1989.
Information Notice 88-23, Supplemerit2, "Potential for Gas Binding of High- Pressure Safety Injection Pumps Dut,ing a Loss-of-Coolant Accident,"
January 31, 1990.
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 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 by Accumulator
Nitrogen Injection," issued September 13. 1989. '7 Information Notice 88-23, Supplement 2, "Potential for Gas ing of High- Pressure Safety Injection Pumps During a Loss-of-Coolant ideiit," issued
January 31, 1990.
Information Notice 90-64. "Potential for Common-Mod Tailure of High Pressu re
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
December 30. 1990.
Information Notice 88-23, Supplement /"Potential for Gas Binding of High- Pressure Safety Injection Pumps Durii a Loss-of-Coolant Accident," issued
December 18, 1992.
Information Notice 93-93. "Inade4ate 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 inthis 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 reviewed and concurred on October 18, 1996.
At chment: List of Recently Issued NRC Information Notices
Contacts BC/SRXB:DSSAT0 BC/PECB:DRPM D/DRPM
NAME EBennerrtr6 4X AChaffee TMartin
WLyon /0/lX, 'z: zgt,_4ll
DATE On)I 6"I /'I/ /96 / /96
____
7t 1/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
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Water . 301- EL 351 EL Top of He(d
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,: 2330 EL Indicatore . Ntogn. 1 9Fae 270" EL
>(^i\ HotLeg aDbl o; l
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Gas
LOOb1°P
Wate Lin
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Coolant Pup(Loop
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(Lin
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Reactor
El. 185"
EL 172" -/
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inftO
Reactor l i nt Oft Dl ?* -
CHEMICAL & VOLUME CONTROL SYSTEM
NITROGEN GAS LEAK PATH FROM VOLUME
CONTROL TANK TO THE RCS
To RCS
Loop #2 Volume Control
Cold Leg Tank
(
Valve Closed -
Leaking By
c
Borde
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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 Modifications to Con- 12/10/96 All holders of OLs
tainment Blowout Panels or CPs for nuclear
Without Appropriate reactors
Design Controls
96-63 Potential Safety Issue 12/05/96 All U.S. Nuclear
Regarding the Shipment Regulatory Commission
of Fissile Material licensees authorized
to possess special
nuclear material in
unsealed quantities
greater than a critical
mass
96-62 Potential Failure of the 11/20/96 All holders of OLs
Instantaneous Trip Function and CPs for nuclear
of General Electric RMS-9 power plants
Programmers
96-61 Failure of a Main Steam Safety 11/20/96 All holders of OLs or
Valve to Reseat Caused by an CPs for nuclear power
Improperly Installed Release reactors
Nut
96-60 Potential Common-Mode Post- 11/14/96 All holders of OLs or
Accident Failure of Residual CPs for nuclear power
Heat Removal Heat Exchangers reactors
96-59 Potential Degradation of 10/30/96 All holders of OLs or
Post Loss-of-Coolant CPs for nuclear power
Recirculation Capability reactors
as a Result of Debris
96-58 RCP Seal Replacement with 10/30/96 All holders of OLs or
Pump on Backseat CPs for pressurized-water
reactors
OL = Operating License
CP = Construction Permit