Information Notice 1989-49, Failure to Close Service Water Cross-Connect Isolation Valves
'4-1
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF NUCLEAR REACTOR REGULATION
WASHINGTON, D.C.
20555
May 22, 1989
NRC'INFORMATION NOTICE NO. 89-49: FAILURE TO CLOSE SERVICE WATER CROSS-
CONNECT ISOLATION VALVES
Addressees
All holders of operating licenses or construction permits for nuclear power
reactors.,'
Purpose
- '.
This information notice is being provided to alert addressees to potential
problems that may result from failure to close isolation valves in service
water system loop cross-connect piping during certain scenarios. It is
expected that recipients will review the information for applicability to
their facilities an'd consider actions, as appropriate, to avoid similar
problems.
However, suggestions contained in this information notice do
not constitute NRC requirements;. therefore, no specific action or written
response is required.
Description of Circumstances
While. Nine Mile Point Unit 2 was shutdown in October 1988 for refueling, the licensee reviewed the control logic which actuates certain service
water valves which are used to isolate redundant loopsof service water.
It'was determined that a loss-of-offsite power with a single failure. (i.e.,
failure to start one of two diesel generators), could lead to loss of the
operating diesel generator, due to inadequate cooling water flow from the
service water system.
The service water system at Nine Mile Point Unit 2 consists of two cross- connected and redundant cooling loops (divisions), each with service water
pumps and various loads, including a diesel generator.
(A third diesel
generator dedicated to high-pressure core spray takes cooling water from
either loop, but it does not provide emergency ac power for any other
function.) During normal operation, the isolation valves in the cross- connect piping are open so that any combination of service water pumps
may be used to provide cooling water to all loads. In response to a
loss-of-offsite power, the isolation valves should close so that each
loop will operate independently of the other. With a loss-of-offsite
8905160204 '
-
IN 89-49 May 22, 1989 power, the control logic would ensure that closure of-the isolation valves- would occur after power is restored from either offstte-sources or the;
diesel generators.' However, if one of the diesel generators fails to
operate, power would be supplied to only one ESF division.
-
The design deficiency in the control logic involved the need for power to
actually exist on ESF buses,.in both divisions for either of two isolation
valves to close. Therefore, the isolation valves would not close when there
was a loss-of-offsite power and the failure of one diesel generator. With the
valves open the cooling water flow provided by a single service water pump.
associated with the operable diesel generator would be distributed to-all
loads in both loops.
As .a
result, it was postulated that with open valves
in the cross-connect piping, there would be inadequate cooling water flow---
in the service water loop with the operable diesel generator, and that diesel
generator would probably fail due to overheating. The control logic design
deficiency has existed since the plant was initially constructed and the:';
licensee's pre-operational routine surveillance and post.maintenance/
modification testing did not detect the design deficiency. The licensee
subsequently made changes' to the control logic that eliminated the single
failure deficiency.
'
The licensee for the Cooper Nuclear Station was concerned about having an ade- quate flow of servitcewater to essential loads following a loss-of-coolant
-accident 'iven-a loss-of -offsite- power and -the-failure-of -the- number-l1-iesal
-
generator to start. Without power from this diesel generator, the single
motor operated block valve which would automatically close to isolate non- essential loads from the essential loads would fafl'to close. Without valve
closure, there may be inadequate.flow to the essential service water loads
and a 'Single service water pump could Se operating in a runout condition.
This problem was identified during the construction and licensing phase, but station-procedures we're not modified adeqouately to mitigate the concern
over pump-runout with a potential'for loss of flow. The licensee modified
procedures to assure that reactor operators take steps to close another valve
in the cross-connect piping that would isolate the nonessential loads, there- by assuring adequate cooling water flow to essential loads, including the
operating diesel generator.
Discussion:
With the service water system 'cross-connect valve-closure problems as des cribed
above, the 'loss-of-offsite power and a single failure could result in a station
blackout. Because the potential consequences are significant, licensees have
evaluated possible improvements such as'reducing cooling water flow to non- essential components following a loss-of-offsite power event, changing the
control logic so that loop isolation occurs with power available to only one
division 'and clarifying procedures that specify corrective operator actions
to ensure that adequate service water flow to the essential components is
maintained.
IN 89-49 May 22, 1989 No specific action or written response is required by this information
notice. If you have any questions about this matter, please contact the
technical contact listed below or the Regional Administrator of the
appropriate regional office.
I t
.
I
aeles E. Rossi, Director
Division of Operational Events Assessment
Office of Nuclear Reactor Regulation
Technical Contact:
J. Carter, NRR
(301) 492-1194 Attachment: List of Recently Issued NRC Information Notices
-
.
..
Attachrtrt
May 22, 1989
Page I of I
LIST OF RECENTLY
ISSUED
NRC INFORIATION NOTICES
Information
NOtice No.
Subject
89-4E
Design Deficiency in the
Turbine-Driver. Auxiliary
Feedwater Pump Coolinc
Water System
Potential Problems With
Worn or Distorted hose
Clamps on Self-Contained
Breathing Apparatus
Confidentiality cf
Exercise Scenarios
89-45 Metalclad, Low-Voltage
Power Circuit Breakers
Refurbished with Sub- standard Parts
89-44
Hydrogen Storace on the
Roof of the Control Room
88-82,
Torus Shells with Corrosion
Supp. I
and Degraded Coatings in
BWR Containments
B9-4
Permanent DWformation of
Torque Switch Helical
Springs in Limitorque
SMA-Type Motor Operators
88-97.
Potentially Substandard
Supp. I
Valve-Replacement Parts
89-42
Failure of Rosemount
Models 1153 and 1154
Transmitters
- Operating License
- Construction Pern;it
Date of
Issuance
Issued 'to
5/22/89'
All holders of OLs
-or CPs for. nuclear
power reactors.
5/18/89
All holders of OLs
or CPs for nuclear
power reactors and
fuel facilities.
5/11/89
All holders of licenses
for fuel cycle facilities
and byproduct material
licensees having an
approved emergency
response plan.
5/8/89
All holders of OLs
or CPs-for nuclear
power reactors.
4/27/89
All holders of OLs
'Or CPs for' nuclear
power reactors.
5/2/89
All holders of OLs
5/1/89
All holders of OLs
or CPs for nuclear
power reactors.
4/28/89
All holders of OLs
or CPs- for-nuclear
power reactors.
4/21/89
All holders of OLs
or CPs for nuclear
power reactors.
power reactors.
UNITED STATES
'NUCLEAR REGULATORY COMMISSION
WASHINGTON, D.C. 20555
OFFICIAL BUSINESS
PENALTY FOR PRIVATE USE, $300
FIRST CLASS MAIL
POSTAGE & FEES PAID
PERMIT No. 047
IN 89-49 May 22, 1989 No specific action or written response is required by this information
notice. If you have any questions about this matter, please contact the
technical contact listed below or the Regional Administrator of the
appropriate regional office.
Charles E. Rossi, Director
Division of Operational Events Assessment
Office of Nuclear Reactor Regulation
Technical Contact:
J. Carter, NRR
(301) 492-1194 Attachment:
List of Recently Issued NRC Information Notices
-
I
- SEE PREVIOUS CONCURRENCE
- EAB:NRR
JCarter:db
5/12/89
- EAB: NRR
PBaranowsky
5/2/89
- TECH:ED *C:EAB:NRR
WDLanning
/ /89
5/8/89
- C:OGCB:NRR
CHBerlinger
5/12/89
5 //89
1989 No specific action or written response is required by this information
notice. If you have any questions about this matter, please contact the
technical contact listed below or the Regional Administrator of the
appropriate regional office.
Charles E. Rossi, Director
Division of Operational Events Assessment
Office of Nuclear Reactor Regulation
Technical Contact:
J. Carter, NRR
(301) 492-1194 Attachment:
List of Recently Issued NRC Information Notices
-
- SEE PREVIOUS CONCURRENCE
bR
- EAB:NRR *TECH:ED
J rter:db PBaranowsky
.C//2/89
/
/89
/ /89
- C:EAB:NRR
WDLanning
/
/89 C:OGCB:NRR
CHBerlinger
.j1 i.;q9 D:DOEA:NRR
CERossi
/ /89
IN 89- May , 1989 The design deficiency in the control logic was that for either isolation
valve to close, power must actually exist on ESF buses in both divisions.
Therefore, the isolation valves would not close upon loss of offsite power and
the failure of one diesel generator. With the valves open the cooling water
flow provided by the service water pump associated with the operable diesel
generator would be distributed to all loads in both loops. As a result, it
was postulated that with open valves in the cross-connect piping, there would
be inadequate cooling water flow in the service water loop with the operable
diesel generator, and that diesel generator would probably fail due to
overheating.
Discussion:
With the service water system cross-connect valve isolation logic as described
above, the loss of offsite power and a single failure could result in a
station blackout. Because the potential consequences of this design deficiency
are significant, the licensee is evaluating possible corrections, such as
reducing, cooling water flow to non-vitil components following a loss-of-power
event and changing the control logic so that loop isolation occurs with power
available to only one division. The control logic deficiency was present
since the plant was initially constructed. The licensee's pre-operational
routine surveillance and post maintenance/modification testing did not detect
the design deficiency.
No specific action or written response is required by this information
notice. If you have any questions about this matter, please contact the
technical contact listed below or the Regional Administrator of the
appropriate regional office.
_
Charles E. Rossi, Director
Division of Operational Events Assessment
Office of Nuclear Reactor Regulation
Technical Contact:
J. Carter, NRR
(301) 492-1194 Attachment: List of Recently Issued NRC Information Notices
- SEE PREVIOUS PAGE FOR CONCURRENCE
- EAB:URR
- EAB:KRR
- TECH:ED
C
-t
C:OGCB:NRR
D:DOEA:NRR
JCarter:db
PBaranowsky
WDLanning
CHBerlinger CERossi
5/1/89
5/2/89
5/ /89
5/6/89
5/ /89
5/ /89
IN 89- May
, 1989 Page 3 of
No specific action or written response is required by this information
notice. If you have any questions about this matter, please contact the
technical contact listed below or the Regional Administrator of the
appropriate regional office.
Charles E. Rossi, Director
Division of Operational Events Assessment
Office of Nuclear Reactor Regulation
Technical Contact:
J. Carter, NRR
(301) 492-1194 Attachment:
List of Recently Issued NRC Information Notices
- YPRR
Carter:db
.
/ I/89 EAB:NRR
PBaranowsky
!5/89
- TECH:ED
C:EAB:NRR
WMLanning
/
/89
/
/89 C:OGCB:NRR
CHBerlinger
/
/89 D:DOEA:NRR
CERossi
/
/89
IN 89-49 May 22, 1989 No specific action or written response is required by this information
notice. If you have any questions about this matter, please contact the
technical contact listed below or the Regional Administrator of the
appropriate regional office.
Charles E. Rossi, Director
Division of Operational Events Assessment
Office of Nuclear Reactor Regulation
Technical Contact:
J. Carter, NRR
(301) 492-1194 Attachment:
List of Recently Issued NRC.Information Notices
I
- SEE PREVIOUS CONCURRENCE
- EAB: NRR
JCarter:db
5/12/89
- EAB:NRR
PBaranowsky
5/2/89
- TECH:ED *C:EAB:NRR
WDLanning
/
/89
5/8/89
- C:OGCB:NRR
CHBerlinger
5/12/89 DO
51/6/89
II
S
J1
89- t'.o , 1989 No specific action or written response is required by this information
notice. If you have any questions about this matter, please contact the
technical contact listed below or the Regional Administrator of the
appropriate regional office.
Charles E. Rossi, Director
Division of Operational Events Assessment
Office of Nuclear Reactor Regulation
Technical Contact:
J. Carter, NRR
(301) 492-1194 Attachment:
List of Recently Issued NRC Information Notices
I'
e
(f)d4 T
- SEE PREVIOUS CONCURRENCE
- 4BNRR
- EAB:NRR *TECH:ED *C:EAB:NRR
J3 arter:db PBaranowsky
WDManning
r I/
2/89
/ /89
/ /89
/ /89 C:OGCB:NRR
CHBerlinger
j / i.;89 D:DOEA:NRR
CERoss i
/ /89
IN 89- V
May , 1989 The design deficiency in the control logic was that for either isolation
valve to close, power must actually exist on ESF buses in both divisions.
Therefore, theisolation valves would not close upon loss of offsite power and
the failure of one diesel generator. With the valves open the cooling water
flow provided by the service water pump associated with the operable diesel
generator would be distributed to all loads In both loops.
As a result, it
was postulated that with open valves in the cross-connect piping, there would
be inadequate cooling water flow in the service water loop with the operable
diesel generator, and that diesel generator would probably fail due to
overheating.
Discussion:
With the service water system cross-connect valve isolation logic as described
above, the loss of offsite power and a single failure could result in a
station blackout. Because the potential consequences of this design deficiency
are significant, the licensee is evaluating possible corrections, such as
,reducing cooling water flow to non-vital components following a loss-of-power
event and changing the control logic so that loop isolation occurs with power
available to only one division. The control logic deficiency was present
since the plant was initially constructed. The licensee's pre-operational
routine surveillance and post maintenance/modification testing did not detect
the design deficiency.
No specific action or written response is required by this Information
notice. If you have any questions about this matter, please contact the
technical contact listed below or the Regional Administrator of the
appropriate regional office.
Charles E. Rossi, Director
Division of Operational Events Assessment
Office of Nuclear Reactor Regulation
Technical Contact:
J. Carter, NRR
(301) 492-1194 Attachment: List of Recently Issued NRC Information Notices
- SEE PREVIOUS PAGE FOR CONCURRENCE
- EAB:NRR
- EAB.NPJM
- TECH:ED
C
(
C:OGCB:NRR
D:DOEA:NRR
JCarter:db
PBaranowsky
W tanning
CHBerlinger CERossi
5/1/89
5/2/89
5/ /89
5/6 /89
5/ /89
5/ /89
N.
IN 89- May , 1989 Page 3 of
No specific action or written response is required by this information
notice. If you have any questions about this matter, please contact the
technical contact listed below or the Regional Administrator of the
appropriate regional office.
Charles E. Rossi, Director
Division of Operational Events Assessment
Office of Nuclear Reactor Regulation
Technical Contact:
J. Carter, NRR
(301) 492-1194 attachment: List of Recently Issued NRC Information Notices
- IERR EAB:NRR
Carter:db PBaranowsky
1 / ( /89
- /89 f .
- TECH:ED
C:EAB:NRR
WDLanning
/ /89
/ /89 C:OGCB: NRR
CHBerlinger
/
/89 D:DOEA:NRR
CERossi
/ /89