Information Notice 2002-18, Effect of Adding Gas Into Water Storage Tanks on the Net Positive Suction Head for Pumps
| ML021570158 | |
| Person / Time | |
|---|---|
| Issue date: | 06/06/2002 |
| From: | Beckner W NRC/NRR/DRIP/RORP |
| To: | |
| Jung I, NRR/DRIP, 415-1837 | |
| References | |
| TAC M3971 IN-02-018 | |
| Download: ML021570158 (5) | |
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF NUCLEAR REACTOR REGULATION
WASHINGTON, DC 20555-0001 June 6, 2002 NRC INFORMATION NOTICE 2002-018: EFFECT OF ADDING GAS INTO WATER
STORAGE TANKS ON THE NET POSITIVE
SUCTION HEAD FOR PUMPS
Addressees
All holders of operating licenses for nuclear power reactors, except those who have
permanently ceased operations and have certified that fuel has been permanently removed
from the reactor.
Purpose
The U.S. Nuclear Regulatory Commission (NRC) is issuing this information notice to alert
addressees to the potential impact of adding gas into water storage tanks on the available net
positive suction head (NPSH) for pumps. The NRC anticipates that recipients will review this
information for applicability to their facilities and consider taking appropriate actions. However, the suggestions contained in this information notice do not constitute NRC requirements and, therefore, no specific action or written response is required.
Description of Circumstances
The NRC recently performed an inspection at the Union Electric Companys Callaway nuclear
power plant in response to the identification of a degraded condensate storage tank (CST)
floating diaphragm seal. The degradation resulted in a failure of a motor-driven auxiliary
feedwater (AFW) pump. It also had the potential to induce a common-cause failure of multiple
AFW pumps. The inspection included a review of several calculations related to the available
NPSH for AFW pumps. The NRC inspection report may be found in the NRC Agency
Document and Management System (ADAMS) under Accession Number ML 020810177.
Prior to 1988, the Callaway nuclear power plant controlled the amount of dissolved oxygen in
the CST water by recirculating water to the main condenser hotwell. However, the licensee
determined that this method of removing oxygen from the CST caused water temperatures to
exceed the allowable water temperature for the AFW system during the summer months. To
prevent high water temperatures, the licensee modified the design to add a nitrogen sparging
system to the CST.
The NRC found that the licensees previous calculations did not appropriately address the effect
of the nitrogen-saturated water on the available NPSH for the AFW pumps. The licensees
recent NPSH calculation included the effect of nitrogen addition to the CST. The revised
calculation indicated that the available NPSH was reduced by approximately 11 feet for the
A-train motor-driven AFW pump.
DISCUSSION
This example at the Callaway nuclear power plant shows that the available NPSH for the AFW
pumps was significantly reduced when nitrogen gas is added to the CST to control dissolved
oxygen. Criterion III, Design Control, in Appendix B to Title 10, Part 50 of the Code of Federal
Regulations (10 CFR Part 50) requires, in part, that each licensee must implement design
control measures to verify or check the adequacy of design through the use of alternate or
simplified calculational methods, or by performing a suitable testing program. In general, it is
important to consider the effect on available NPSH for pumps when modifying the pumps
suction source (e.g., CST and Refueling Water Storage Tank). Inadequate NPSH can result in
significantly degraded pump performance or pump failure.
This information notice does not require any specific action or written response. If you have
any questions about the information in this notice, please contact the technical contacts listed
below or the appropriate project manager from the NRCs Office of Nuclear Reactor Regulation.
/RA/
William D. Beckner, Program Director
Operating Reactor Improvements Program
Division of Regulatory Improvement Programs
Office of Nuclear Reactor Regulation
Technical contact: Ian Jung, NRR Troy Pruett, Region IV
(301) 415-1837 (817) 860-8182 Email: ixj@nrc.gov Email: twp@nrc.gov
Attachment: List of Recently Issued NRC Information Notices
DISCUSSION
This example at the Callaway nuclear power plant shows that the available NPSH for the AFW
pumps was significantly reduced when nitrogen gas is added to the CST to control dissolved
oxygen. Criterion III, Design Control, in Appendix B to Title 10, Part 50 of the Code of Federal
Regulations (10 CFR Part 50) requires, in part, that each licensee must implement design
control measures to verify or check the adequacy of design through the use of alternate or
simplified calculational methods, or by performing a suitable testing program. In general, it is
important to consider the effect on available NPSH for pumps when modifying the pumps
suction source (e.g., CST and Refueling Water Storage Tank). Inadequate NPSH can result in
significantly degraded pump performance or pump failure.
This information notice does not require any specific action or written response. If you have
any questions about the information in this notice, please contact the technical contacts listed
below or the appropriate project manager from the NRCs Office of Nuclear Reactor Regulation.
/RA/
William D. Beckner, Program Director
Operating Reactor Improvements Program
Division of Regulatory Improvement Programs
Office of Nuclear Reactor Regulation
Technical contact: Ian Jung, NRR Troy Pruett, Region IV
(301) 415-1837 (817) 860-8182 Email: ixj@nrc.gov Email: twp@nrc.gov
Attachment: List of Recently Issued NRC Information Notices
DISTRIBUTION:
PUBLIC
IN Reading File
ADAMS ACCESSION NO.: Template: NRR-052 DOCUMENT NAME: G:RORP\OES\JUNG\INCALLAWAY-NPSH.WPD*See previous concurrence
OFFICE RSE:RORP:DRIP TECH EDITOR SC:EMEB:DE SC:SPLB:DSSA SC:RORP:DRIP PD:RORP:DRIP
NAME ICJung PAGarrity* DTerao SWeerakkody TReis WDBeckner
DATE 05/ /2002 05/ 10 /2002 05/21/2002 05/21/2002 05/092002 06/06/2002 OFFICIAL RECORD COPY
Attachment 1 IN 2002-018 LIST OF RECENTLY ISSUED
NRC INFORMATION NOTICES
_____________________________________________________________________________________
Information Date of
Notice No. Subject Issuance Issued to
_____________________________________________________________________________________
2002-16 Intravascular Brachytherapy 05/01/2002 All Medical Licensees.
Misadministrations
2002-15 Hydrogen Combustion Events 04/12/2002 All holders of operating licenses
in Foreign BWR Piping for light water reactors, except
those who have permanently
ceased operations and have
certified that fuel has been
permanently removed from the
reactor.
2002-14 Ensuring a Capability to 04/08/2002 All holders of operating licenses
Evacuate Individuals, Including for nuclear power reactors, Members of the Public, From including those who have ceased
the Owner-Controlled Area operations but have fuel on site.
2002-13 Possible Indicators of Ongoing 04/04/2002 All holders of operating licenses
Reactor Pressure Vessel Head for pressurized water nuclear
Degradation power reactors, except those who
have permanently ceased
operations and certified that fuel
has been permanently removed
from the reactor.
99-28, Supp 1 Recall of Star Brand Fire 03/22/2002 All holders of licenses for nuclear
Protection Sprinkler Heads power, research, and test
reactors and fuel cycle facilities.
2002-12 Submerged Safety-Related 03/21/2002 All holders of operating licenses
Electrical Cables or construction permits for
nuclear power reactors
Note: NRC generic communications may be received in electronic format shortly after they are issued by
subscribing to the NRC listserver as follows:
To subscribe send an e-mail to <listproc@nrc.gov >, no subject, and the following command in the
message portion:
subscribe gc-nrr firstname lastname
______________________________________________________________________________________
OL = Operating License
CP = Construction Permit