Information Notice 1989-32, Surveillance Testing of Low-Temperature Overpressure-Protection Systems
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF NUCLEAR REACTOR REGULATION
WASHINGTON, D.C.
20555
March 23, 1989
NRC INFORMATION NOTICE NO. 89-32: SURVEILLANCE TESTING OF LOW-TEMPERATURE
OVERPRESSURE-PROTECTION SYSTEMS
Addressees
All holders of operating licenses or construction permits for pressurized-water
reactors (PWRs).
Purpose
This information notice is being provided to alert addressees to potential
operability problems due to lack of inservice testing of power-operated relief
valves (PORVs) in their low-temperature overpressure-protection (LTOP) mode.
It is expected that recipients will review the information for applicability to
their facilities and consider actions, as appropriate, to avoid similar prob- lems.
However, suggestions contained in this information notice do not consti- tute NRC requirements; therefore, no specific action or written response is
required.
Description of Circumstances
Beaver Valley:
During an inspection (Inspection Report No. 50-334, 412/86-20),
NRC inspectors noted that technical specifications (TS) require that over- pressure protection be provided by two PORYs with a nominal trip setpoint of
less than or equal to 350 psig whenever the temperature of a non-isolated
reactor coolant system (RCS) cold leg is less than or equal to 2750F. The TS
surveillance requirement only addresses stroking the operable PORY each time
the plant enters Mode 5 (cold shutdown) unless that PORY has been tested within
the preceding three months.
The licensee analyzed two cases for an overpressure accident scenario:
(1) a
mass input case and (2) a heat input case.
The most restrictive PORY opening
time was identified as the mass input accident which would require a valve to
open within 2.5 seconds.
An NRC safety evaluation report (SER) dated April 4,
1983 found this analysis to be acceptable. A review of the licensee's mainte- nance surveillance procedure indicated that the nominal trip setpoint of less
than or equal to 350 psig was addressed, but the stroke time was not.
Plant TS and procedures had not implemented PORV stroke times as assumed in the
analysis. The licensee performed an evaluation using data from the station's
ASME Valve Stroke Log, when compared to SER stroke time assumptions. The licensee
(8903170419 Zt
)
IN 89-32 March 23, 1989 concluded that the resulting maximum RCS pressure would still have been within
specified limits.
However, the licensee initiated several procedural improve- ments to address PORY stroke testing.
Turkey Point: The staff inspected the licensee's overpressure mitigation
system (MS) (Inspection Report Nos. 50-250, 251/88-14 and 88-26).
The PORY
electronics operability and setpoints are verified before being aligned for
low-pressure operations. The inspectors reviewed the stroke times for the Unit
3 and 4 PORVs from May 1984 through May 1988. These tests were performed in
accordance with the licensee's inservice test (IST) program.
The IST require- ment for each PORV is to fully stroke within 15 seconds.
The stroke times
reviewed ranged from less than 2.0 seconds up to 6.41 seconds.
These stroke
times are well below the 15-second IST criterion.
However, in analyses sup- porting license amendments, a relief valve opening time of 2.0 seconds was
assumed in calculating the setpoint overshoot for the mass input case. The
heat input case assumed a relief valve opening time of 3.0 seconds. The PORVs, on average, were not meeting the design-basis stroke time.
The licensee requested relief from the TS requirement in order to prepare for
the eventual refueling outage that would place one of the units within the
operating regime of the OMS.
The request extended to the next refueling outage
for each of the units in order to allow the licensee time to resolve this
issue. The licensee requested that Westinghouse perform an analysis to determine
the magnitude of the overshoot considering the-followingtransients
1) the
_
start of-an~--dT-
ieact6rc6olaint pump with the secondary water temperature
of the steam generator less than or equal to 500 F above the RCS cold-leg
temperature; 2) the start of a high pressure safety injection pump and Its
injection into a water-solid RCS and 3) the inadvertent start of two charging
pumps with a loss of letdown.
The safety evaluation demonstrated that with a
PORY opening stroke time up to 3.45, the OMS could mitigate the most limiting
transient (spurious start of a ST pump).
The licensee has completed a design
change for Unit 4 and is planning to implement the design change on Unit 3 during the next refueling outage.
This design change will ensure that the
PORVs will open in time to prevent exceeding the 10 CFR 50, Appendix G limits.
The surveillance procedures supporting the TS were changed so that future
stroke time testing will use an acceptance criterion that is consistent
with the design basis.
Shearon Harris:
NRC inspectors assessing operational performance (Inspection
Report No. 50-400/88-34) noted a discrepancy concerning the testing of the
pressurizer PORYs.
An IST procedure specified that the PORYs were to be stroke
tested from the open to closed position with a maximum stroke time of 2.0
seconds. The licensee tested the PORVs in accordance with an 18-month surveil- lance test for pressurizer PORY operability. Although no safety analysis
credit was taken for the PORYs at power operation, they were required to
provide overpressure protection (by opening on demand) during low-temperature
operation.
Shearon Harris utilizes two of the three PORYs for the LTOP system.
IN 89-32 March 23, 1989 The design basis of the licensee's LTOP is to protect the RCS from overpressure
when the transient is limited to:
(1) start of an idle reactor coolant pump
with secondary-side water temperature less than 50F above RCS cold-leg temper- ature or (2) start of a charging safety injection pump and its injection into a
water-solid RCS.
The PORY setpoints were calculated to maintain the RCS below
the maximum allowable system pressure given in 10 CFR 50 Appendix G. The
setpoint calculations assumed a valve opening time of 2.0 seconds in determin- ing the possible overshoot. The inspectors noted that if the actual valve
opening times were greater than 2.0 seconds, then the pressure overshoot could
be greater than originally calculated. A significant increase in valve opening
time could result in the 10 CFR 50 Appendix G limits being exceeded during a
design-basis transient.
The PORYs were stroked in the open direction so that the licensee could perform
the time-to-close test.
However, the surveillance procedure did not require
that the time to open be determined, and this was not done.
Discussion:
The basic issue in these three cases is that the licensee's inservice testing
of its low-temperature overpressure-protection (LTOP) systems may be inade- quate. Stroke time requirements used in analyses of the licensee's LTOP
systems were not being transferred into IST requirements and eventually into
surveillance test procedures. The ASME Code,Section XI, paragraph IWV-3400,
requires valves to be exercised to the position required to fulfill their
function. Therefore, not testing the LTOP PORYs in the open direction is a
concern.
No specific action or written response is required by this information notice.
If you have any questions about this matter, please contact one of the tech- nical contacts 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 Contacts: Milton Shymlock, RII
(404) 331-5542 Thomas McElhinney, Res. Insp., Turkey Pt.
(305) 245-7669 Attachment:
List of Recently Issued NRC Information Notices
Attachaent
March 23. 1989
Pap 1 of I
LIST OF RECENTLY ISSUED
NRC INFORMATION NOTICES
information
Date of
Notice No.
Subject
Issuance
Issued to
89-31 Swulling and Cracking
3/22/89
All holders of OLs
of Hafni1m Control Rods
or CPs for PVRI with
Hafniua control rods.
89-30
High Tperature
3/15S89
All holders of CLs
Enviroiments at
or CPs for nuclur
Nuclear Power Plants
power re ctors.
89-2S
Potential Failure of
3/15/89
All holders of OMs
ASEA Brown Boveri
or CPs for nuclear
Circuit Breakers
powr ructors
During Seismic Event
8928 Weight and Center of
3/14189
All holders of OLs
Gravity Discrepancies
or CPs for nuclear
for Copes-Vulcan
Power re ctors.
Air-Operated Valves
89-27 Limitations on the Use
3/8/89
All holders of Ots
of Waste Forms and High
or CPs for nuclear
Integrity Containers for
power reactors, fuel
the Disposal of Low-Level
cycle licenses and
Radioactive Waste
certaim by-product
materials licenses.
89-26 Instrument Air Supply to
3/7/89 All holders of 04.
Safety-Related Equipment
or CPs for nuclear
power reactors.
89-25 Unauthorized Transfer of
3/7/89 All U.S. NRC source.
O1ership or Control of
byproduct, and special
Licensed Activities
nuclear material
licensees.
89-24 Nuclear Criticality Safety
3/6/89
All fuel cycle
licensees and other
licensees possessing.
mo
than critical
mass quantities of
special nuclear
material.
O.
- Operating License
- Construction Permit
I
UNITED STATES
NUCLEAR REGULATORY COMMISSION
WASHINGTON, D.C. 20555
OFFICIAL BUSINESS
PENALTY FOR PRIVATE USE, $300
FIRST CLAS MAII
POSTAGE & FEES PAID
PERMIT No. 0-9
IN 89-32 March 23, 1989 The design basis of the licensee's LTOP is to protect the RCS from overpressure
when the transient is limited to:
(1) start of an idle reactor coolant pump
with secondary-side water temperature less than 500F above RCS cold-leg temper- ature or (2) start of a charging safety injection pump and its injection into a
water-solid RCS. The PORY setpoints were calculated to maintain the RCS below
the maximum allowable system pressure given in 10 CFR 50 Appendix G. The
setpoint calculations assumed a valve opening time of 2.0 seconds in determin- ing the possible overshoot.
The inspectors noted that if the actual valve
opening times were greater than 2.0 seconds, then the pressure overshoot could
be greater than originally calculated. A significant increase in valve opening
time could result in the 10 CFR 50 Appendix G limits being exceeded during a
design-basis transient.
The PORVs were stroked in the open direction so that the licensee could perform
the time-to-close test. However, the surveillance procedure did not require
that the time to open be determined, and this was not done.
Discussion:
The basic issue in these three cases is that the licensee's inservice testing
of its low-temperature overpressure-protection (LTOP) systems may be inade- quate.
Stroke time requirements used in analyses of the licensee's LTOP
systems were not being transferred into IST requirements and eventually into
surveillance test procedures. The ASME Code,Section XI, paragraph IVIV-3400,
requires valves to be exercised to the position required to fulfill their
function. Therefore, not testing the LTOP PORVs in the open direction is a
concern.
No specific action or written response is required by this information notice.
If you have any questions about this matter, please contact one of the tech- nical contacts 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 Contacts: Milton Shymlock, RII
(404) 331-5542 Thomas McElhinney, Res. Insp., Turkey Pt.
(305) 245-7669 Attachment:
List of Recently Issued NRC Information Notices
Transmitted by memo to Carl Berlinger from RII dated 12/8/88
- SEE PREVIOUS CONCURRENCES
C/OGCB: DOEA:NRR
CHBerlinger
03// 89
/89
- OGCB:DOEA:NRR
- EMEB:DEST:NRR *SRXB:DEST:NRR RII
- RPB:ARM
NPKadambi
LBMarsh
MWHodges
MShymlock
TechEd
02/27/89
03/02/89
03/02/89
03/ /89
03/02/89
IN 89-XX
March xx, 1989 protection (by opening on demand) during low-temperature operation.
Shearon
Harris utilizes two of the three PORVs for the LTOP system.
The design basis of the licensee's LTOP is to protect the RCS from overpressure
when the transient was limited to:
(1) start of an idle reactor coolant pump
with secondary-side water temperature less than 500F above RCS cold-leg temper- ature or (2) start of a charging safety injection pump and its injection into a
water-solid RCS. The PORV setpoints were calculated to maintain the RCS below
the maximum allowable system pressure given in 10 CFR 50 Appendix G. The
setpoint calculations assumed a valve opening time of 2.0 seconds in determin- ing the possible overshoot. The inspectors noted if the actual valve opening
times were greater than 2.0 seconds; then the pressure overshoot could be
greater than originally calculated. A significant increase in valve opening
time could result in the 10 CFR 50 Appendix G limits being exceeded during a
design-basis transient.
The PORVs were stroked in the open direction so that the licensee could perform
the time-to-close test.
However, the surveillance procedure does not require
that the time to open be determined, and this was not done.
Discussion:
The basic issue in these three cases is that the licensee's inservice testing
of its low-pressure overpressure-protection (LTOP) systems may be inadequate.
Stroke time requirements stipulated in safety evaluation reports of the
licensee's LTOP systems were not being transferred into IST requirements and
eventually, into surveillance test procedures. The ASME Code,Section XI,
paragraph IWV-3400, requires valves to be exercised to the position required to
fulfill their function.
Therefore, not testing the LTOP PORVs in the open
direction is a concern.
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 Contacts:
Milton Shymlock, RII
(404) 331-5542 Thomas McElhinney, Res. Insp., Turkey Pt.
(305) 245-7669 Attachment:
qist nf Rpepntlv Issued NRC Information Notices
Transmitted by memo to Carl Berlinger from RII dated 12/8/88
0
- SEE PREVIOUS CONCURRENCES
D/DOEA:NRR
C/OGCB:DOEA:NRR
CERossi
CHBerlinger
03/ /89
03/ /89
- OGCB:DOEA:NRR
- EMEB:DEST:NRR *SRXB:DEST:NRR RII- reAl
Q
- RPB:ARM
NPKadambi
LBMarsh
MWHodges
MShyml oI
echEd
02/27/89
03/02/89
03/02/89 O3/69/89 kjj..
03/02/89
IN 89-XX
February xx, Page 2 of
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 Contacts:
Milton Shymlock, RII
(404) 331-5542 Thomas McElhinney, Res. Insp.,
(305) 245-7669 Turkey Pt.
Attachment:
List of Recently Issued NRC Information Notices
- Transmitted by memo to Carl Berlinger from R T
dated _
__-_
OGC:DOEA:NRR
NPKadambi
02/27/89 EB:DEST:NRR
LBMarsh
0
/89
3 PL
B:DEST:NRR
MWHodges
Y/;z /89 D/DOEA:NRR
CERossi
02/ /89 RII
MShymlock
02/ /89 C/OGCB:DOEA:NRR
CHBerlinger
02/ /89 RPB:ARM
TechEd
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