Information Notice 1991-56, Potential Radioactive Leakage to Tank Vented to Atmosphere
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF NUCLEAR REACTOR REGULATION
WASHINGTON, D.C.
20555
September 19, 1991
NRC INFORMATION NOTICE 91-56: POTENTIAL RADIOACTIVE LEAKAGE TO TANK.:VENTED
TO ATMOSPHERE.
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 potential problems resulting from the leakage of isola- tion valves in emergency core cooling system :(ECCS) recirculation lines to the
safety injection water storage tank, whlich-may be.vented to atmosphere. 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 require- ments; therefore, no specific action or written response is required.
Description of Circumstances
In September 1990, the Consumers Power Company, the licensee for the Palisades
Plant, performed a test to measure the leakage through-the suction valves from
the safety injection and refueling wateritank (SIRWT; see figure 1). The
licensee concluded that leakage through the suction valves was not a concern, but that radioactivity could be released throughetwo other.leakage paths:
through the ECCS recirculation (minimum flow) header to the SIRWT and through
the ECCS test header to the SIRWT. The concern arises because the'SIRWT is- vented to the atmosphere.
During the-initial phase of recovery from a.loss-of-coolant accident (LOCA),
the ECCS recirculation header collects water from the safety injection pump
minimum flow lines for return to the SIRWT through the minimum flow recircula-.
tion control valves (See Figure 1). During the later recirculation phase of
recovery, this header is isolated from the SIRWT by these two independent
control valves, which are in series. The test header collects water from the
shutdown cooling heat exchangers during ECCS.surveillance testing and during
SIRWT mixing operations for return to-the SIRWT through a manual test valve
(See Figure 1). During reactor operation, the manual test valve is locked
closed, isolating the test header from the SIRWT. .
The leak tightness.of these three isolation valves has.never been previously
verified at the Palisades Plant. The licensee's previous calculations of
9109109
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IN 91-56 September 19, 1991 control room and offsite doses from a maximum hypothetical accident did not
include such valve leakage.
Preliminary estimates indicate that a leak rate of
0.1 gpm, together with other assumed sources, could cause a dose to control
room personnel exceeding the limits in General Design Criterion (GDC) 19,
"Control 'Root," 10 CWR Part 50,' Ap'pendix A.' The'se limits include-a dose 6f
5 rem to the whole body or an equivalent'dose to'any part of the body. A leak
rate of 1 gpm, together with other assumed sources, could cause a dose to
people at the site boundary equal to the limits in 10 CFR Part 100. These
limits include a dose of 25 rem to the whole body or 300 rem to the thyroid
from iodine exposure.
The licensee does not know the rate of leakage and thus can not determine if--
prior analyses underestimate the possible accident consequences. The licensee
determined that excessive valve leakage could cause consequences to be larger:-
than those from previous assessments and could cause the radiological conse- quences at the site boundary and to control room operators to exceed the
regulatory limits.' Therefore, the- licensee's safety' review committee reviewed
this'issue and determined it to be an unreviewed safety question.- The-:licensee- has submitted-a. *:i
ense amendment to the NRC for review.'
The licensee's
justification for continued operation addresses the following -factors:
o
Current confidence-in-valve performance and leak tightness
o
Conservatisms in valve leak rate evaluations
o
System design considerations and their mitigating effects
°
The low probability; of a LOCA-with'fuel damage and a large fission
product release-to'the contalinment'building
o
-Conservatisms in-the'present maximum-hypothetical accident
The licensee is-resolving this concern-by- eliminating-conservative assumptions'
in leak rate evaluations and current maximum hypothetical accident analyses, '-
implementing procedures to lessen the consequences of valve leakage, evaluating
a modif iation-'oUthe. manual-Wvlve,' and including leak rate testingof: the
minimum flow re-circulation control' valves as part of the inservice testing
program, following modifications: scheduled for February 1992.
- '
Discussion .
-
-
-
-
Plants- other-than Palisades may'be- vulnerable to an unmonitored release from
the safety injection-water, storage- taiak- dUring laud following a'postu-lated'
-
design basis accident. Oh August 19, 1991, the,0maha1Public Power bistrict,- the licensee for the Fort Calhouhn'Nuclear Power PlAnt, reported a similar
-
concern with respect to the SIRWT suction valves. In addition, References 1 and 2 provide-.discussioniof somewhat similar situations.-- The NRC staff has
reviewed-the-system design characteristics and the inservice testing programs
IN 91-56 September 19, 1991 of several utilities and has determined that similar conditions, with compara- ble consequences, may exist at other plant sites.
In particular, valves with
similar functions are not identified as Category A valves in inservice testing
programs.
Inservice testing requirements are specified in 10 CFR 50.55a(g), which refer- ences the American Society of Mechanical Engineers (ASME) Boiler and Pressure
Vessel Code,Section XI.
Subsection IWV-2200, "Categories of Valvbs," stipu- lates that Category A valves are those valves with functions in which the
closed valve seat leakage is limited to a specific amount.
The leak test
requirements for Category A valves are specified in Section XI, IWV-3420,
"Valve Leak Rate Test."
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 project manager.
t
les E. Rossi, Director
Division of Operational Events Assessment
Office of Nuclear Reactor Regulation
Technical contacts:
Patricia Campbell, NRR
(301) 492-1311
Brian E. Holian, NRR
(301) 492-1344
Vern Hodge, NRR
(301) 492-1861 Attachments:
1. Figure 1. Partial ECCS Piping Diagram for the Palisades Plant
2. List of References
3. List of Recently Issued NRC Information Notices
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Figure 1. PatlIal ECCS Piping Diagram for the Palisades Plant
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Attachment 2
September 19, 1991 LIST OF REFERENCES
1. NRC Information Notice 85-94, "Potential for Loss of Minimum Flow Paths
Leading to ECCS Pump Damage During a LOCA," December 13, 1985
2. NRC Information Notice 86-38, "Deficient Operator Actions Following Dual
Function Valve Failures," May 20, 1986
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Attachment 3
September 19, 1991 LIST OF RECENTLY ISSUED
NRC INFORMATION NOTICES
Information
Date of
Notice No.
Subject
Issuance
Issued to
91-55
85-18, Supp. 1
91-54
89-90,
Supp. 2
91-53
91-52
86-14, Supp. 2
91-51
91-50
Failures Caused by An
Improperly Adjusted Test
Link In 4.16 KV General
Electric Switchgear
Failures of Undervoltage
Output Circuit Boards In
the Westinghouse-Designed
Solid State Protection
System
Foreign Experience Regard- ing Boron Dilution
Pressurizer Safety Valve
Lift Setpoint Shift
Failure of Remote Shutdown
System Instrumentation
Because of Incorrectly
Installed Components
Nonconservative Errors
In Overtemperature Delta- Temperature (OTaT) Set- point Caused by Improper
Gain Settings
Overspeed Trips of AFW,
HPCI and RCIC Turbines
Inadequate Fuse Control
Programs
A Review of Water Hammer
Events After 1985
09/16/91
All holders of OLs or CPs
for nuclear power reactors.
09/10/91
All holders of OLs or CPs for
Westinghouse (W)-designed
nuclear power reactors.
09/06/91
All holders of OLs or CPs
for pressurized water
reactors (PWRs).
09/05/91
All holders of OLs or CPs
for nuclear power reactors.
09/04/91
All holders of OLs or CPs
for nuclear power reactors.
08/29/91
All holders of OLs or CPs
for Westinghouse (W)-designed
nuclear power reactors.
08/26/91
All holders of OLs or CPs
for nuclear power reactors.
08/20/91
All holders of OLs or CPs
for nuclear power reactors.
08/20/91
All holders of OLs or CPs
for nuclear power reactors.
OL = Operating License
CP = Construction Permit
.
.
i
IN 91-XX
August xx, 1991 the licensee for the Fort Calhoun Nuclear Power Plant, reported a similar
concern with respect to the SIRWT suction valves. In addition, references 1 and 2 provide discussion of somewhat similar situations.
The NRC staff has
reviewed the system design characteristics and the inservice testing programs
of several utilities and has determined that similar conditions, with comparable
consequences, may exist at other plant sites.
In particular, valves with
similar functions are not identified as Category A valves in inservice testing
programs.
Inservice testing requirements are specified in 10 CFR 50.55a(g), which refer- ences the American Society of Mechanical Engineers (ASME) Boiler and Pressure
Vessel Code,Section XI. Subsection IWV-2200, "Categories of Valves,"
stipulates that Category A valves are those valves with functions in which the
closed valve seat leakage is limited to a specific amount. The leak test
requirements for Category A valves are specified in Section XI, IWV-3420,
"Valve Leak Rate Test."
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 NRR project manager.
Charles E. Rossi, Director
Division of Operational Events Assessment
Office of Nuclear Reactor Regulation
Technical Contacts:
Patricia Campbell, NRR
(301) 492-1311
Brian E. Holian, NRR
(301) 492-1344
Vern Hodge, NRR
(301) 492-1861 Attachments:
1. Figure 1. Partial ECCS Piping Diagram for the Palisades Plant
2. List of References
3. List of Recently Issued NRC Information Notices
Document Name: STOR TANK LKG
- SEE PREVIOUS CONCURREN
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07/19/91
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07/11/91
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LBMarsh
07/18/91
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BHolian
07/15/91
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September 19, 1991
of several utilities and has determined that similar conditions, with compara- ble consequences, may exist at other plant sites. In particular, valves with
similar functions are not identified as Category A valves in inservice testing
programs.
Inservice testing requirements are specified in 10 CFR 50.55a(g), which refer- ences the American Society of Mechanical Engineers (ASME) Boiler and Pressure
Vessel Code,Section XI.
Subsection IWV-2200, "Categories of Valves," stipu- lates that Category A valves are those valves with functions in which the
closed valve seat leakage is limited to a specific amount.
The leak test
requirements for Category A valves are specified in Section XI, IWV-3420,
"Valve Leak Rate Test."
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 project manager.
Original Signed by
Charles E. Rossi
Charles E. Rossi, Director
Division of Operational Events Assessment
Office of Nuclear Reactor Regulation
Technical contacts:
Patricia Campbell, NRR
(301) 492-1311
Brian E. Holian, NRR
(301) 492-1344
Vern Hodge, NRR
(301) 492-1861 Attachments:
1. Figure 1. Partial ECCS Piping Diagram for the Palisades Plant
2. List of References
3. List of Recently Issued NRC Information Notices
- SEE PREVIOUS CONCURRENCES
- RPB:PRPB:NRR
- SRXB:DST:NRR
JCunningham
RCJones
09/06/91
08/23/91
- C/OGCB:DOEA:NRR*RPB:ADM
CHBerlinger
TechEd
08/22/91
06/28/91
- OGCB:DOEA:NRR *EMEB:DET:NRR
CVHodge
PCampbell
07/11/91
07/11/91 D/
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- D/DRPW:NRR
JZwolinski
BABoger
07/19/91
07/19/91
- C/EMEB:DET:NRR*D/DET:NRR
JNorberg
JRichardson
07/11/91
07/10/91
- D/PD3-1:DRPW:NRR
LBMarsh
07/18/91
- PD3-1:DRPW:NRR
BHolian
07/15/91 Document Name: IN 91-55
IN 91-XX
July xx, 1991 comparable consequences, may exist at other plant sites. In particular,
10 CFR 50.55a(g) references the American Society of Mechanical Engineers (ASME)
Boiler and Pressure Vessel Code,Section XI, IWV-2200, "Categories of Valves,"
which stipulates that Category A valves be used for those functions in which
the closed valve seat leakage is limited. The leak test requirements for
Category A valves are specified in Section XI, IWV-3420, "Valve Leak Rate
Test."
This information notice requires
you have any questions about the
of the technical contacts listed
no specific action or written response. If
information in this notice, please contact one
below or the appropriate NRR project manager.
arles E. Rossi, Director
D
sion of Operational Events Assessment
Off e of Nuclear Reactor Regulation
Technical Contacts: Patricia Campbell, NRR
(301) 492-1311
Brian E. Holian, NRR
(301) 492-1344
Vern Hodge, NRR
(301) 492-1861 Attachments:
1. Figure 1. Partial ECCS Piping Diagram for the Palisade Plant
2. List of References
3. List of Recently Issued NRC Information Notices
Document Name: STOR TANK LKG
- SEE PREVIOUS
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1. Figure 1. Partial ECCS Piping Diagram for the Palisades Plant
2. List of References
3. List of Recently Issued NRC Information Notices
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