View source for Information Notice 2004-07, Plugging of Safety Injection Pump Lubrication Oil Coolers with Lakeweed

{{Adams
| number = ML040770145
| issue date = 04/07/2004
| title = Plugging of Safety Injection Pump Lubrication Oil Coolers with Lakeweed
| author name = Beckner W
| author affiliation = NRC/NRR/DIPM/IROB
| addressee name = 
| addressee affiliation = 
| docket = 
| license number = 
| contact person = Foster J, NRR/IROB, 415-3647
| document report number = IN-04-007
| document type = NRC Information Notice
| page count = 6
}}
{{#Wiki_filter:UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, DC 20555-0001 April 7, 2004 NRC INFORMATION NOTICE 2004-07:                       PLUGGING OF SAFETY INJECTION PUMP

LUBRICATION OIL COOLERS WITH

LAKEWEED1

==Addressees==
:
All holders of operating licenses or construction permits for nuclear power reactors, except

those who have permanently ceased operations and have certified that fuel has been

permanently removed from the reactor vessel.

==Purpose==
:
The U.S. Nuclear Regulatory Commission (NRC) is issuing this information notice (IN) to alert

addressees to plugging of the high-pressure safety injection pump lubrication oil coolers with

lakeweed, which occurred at the Kewaunee Nuclear Power Plant (KNPP), a pressurized-water

reactor, during full-power operations. The NRC expects recipients to review the information

in this notice for applicability to their facilities and consider actions, as appropriate, to avoid

similar problems. However, suggestions contained in this information notice do not constitute

NRC requirements and, therefore, do not require any specific action or written response.

==Description of Circumstances==
:
At the time of this event, the safety injection pump lubrication (lube) oil coolers at KNPP

were horizontal, straight tube, two-pass heat exchangers with twenty G-inch (0.95-cm)
(outer diameter) tubes per pass. Lubrication oil from the high-pressure safety injection pumps

circulated on the shell side, and service water from Lake Michigan passed through on the tube

(service water) side.

On January 15, 2004, during a routine quarterly maintenance inspection of the A safety injection

pump lube oil cooler, visual examination revealed silt and biological blockage (lakeweed)
at 17 of 20 tube pass inlets. The "as-found" tube-side flow measured 3.0 to 3.8 gallons/minute

(gpm) (11.4 to 14.4 liters/minute, lpm) before cleaning, and 5.95 to 6.05 gpm (22.5 to 22.9 lpm)
after cleaning. This concern prompted an investigation into the condition of the B safety

injection pump lube oil cooler, during which the licensee determined that 17 of 20 tubes in each

pass of this cooler were also blocked. A flow test, conducted with the cooler's end bell

removed, revealed that there was no flow from 17 of the 20 tubes, as seen from the outlet of

the cooler, and the "as-found" flow rate measured similar to that of the A safety injection pump

lube oil cooler.

ML040770145
1 Throughout this report, "lakeweed" is considered a mixture of plant fiber, diatom, algae filament, fungi, protozoa, and bacteria. The licensee and the NRC believe that the small tube diameter and tube sheet design

contributed to the lakeweed fouling on the tube side of the lubrication oil coolers.

The licensee determined that this condition had potentially rendered both safety injection pump

trains inoperable, and this discovery raised doubts regarding the future operability of the safety

injection pumps. As a result, plant operators declared both trains of the high-pressure safety

injection system inoperable at 12:20 a.m. on January 16, 2004, and initiated a plant shutdown

at 1:20 a.m. the same day.

Discussion:
Generic Letter (GL) 89-13, Service Water System Problems Affecting Safety-Related

Equipment, requested that licensees evaluate system heat exchangers that perform safety- related functions. The NRC also requested that licensees initiate a maintenance, test, and

inspection program (as necessary) to comply with GL 89-13 and General Design Criterion

(GDC) 44, Cooling Water, as defined by Appendix A to Title 10, Part 50, of the Code of

Federal Regulations (10 CFR Part 50). The GL further stated that licensees programs should

account for heat exchanger fouling, plugging, and the potential for reduced flow and heat

removal capability.

With respect to safety injection pump coolers, the operability assessment would (as a minimum)
evaluate the delivered flow with the service water system in accident alignment, service water

temperature at its design limits (upper and lower bounds), and the safety injection pump moving

fluid at accident temperatures for a prolonged period of time (i.e., for the duration of the post- accident function).

Operating experience at KNPP and another operating plant shows that fouling with lakeweed

is a concern with heat exchangers that have an inner diameter (ID) of less than 1/2 inch

(1.27 cm). This concern is heightened if the heat exchanger in question is in a low point

in the system and experiencing low flow. Coolers with higher flow velocities and larger diameter

heat exchanger tubes have been shown to be less susceptible to fouling and flow blockage.

The higher velocities tend to keep solids suspended, and the larger diameter tubing provides

less potential for the accumulation of lakeweed or other marine organisms at the tube inlets.

Instances of lakeweed fouling of safety-related heat exchangers have occurred at other sites, as follows (this is not an all-inclusive list):
*        Point Beach Nuclear Plant experienced lakeweed clogging of the G1/G2 diesel coolers.

The heat exchangers had G-inch (0.95-cm) tubes.

*        R.E. Ginna Nuclear Power Plant has diesel generator cooling with two lube oil and

jacket water heat exchangers in series, one with G-inch (0.95-cm) tubes, and the other

with 1/2-inch (1.27-cm) tubes. Ginna has not experienced significant blockage of the

larger tubing but has reported blockage on the smaller tubing and continues to monitor

lakeweed fouling on all the heat exchangers. *        Brunswick Steam Electric Plant, Unit 1, noted that cooling flow to both residual heat

removal pump seal coolers was approximately 1 gpm (3.8 lpm). The licensee removed

the coolers from service and found that they were partially filled with silt. The seal

coolers are in a low point of the service water system. Upon opening these coolers, the

licensee frequently discovers lakeweed creating a matte over the inlet tubesheets.

Licensees need to be aware that plugging and blockage of heat exchanger tubing attributable

to a buildup of silt, sand, or biological material may decrease the ability of the heat exchanger

or cooler to perform its required heat removal function. This may also affect other safety- related components, such as pumps; emergency diesel generators; and heating, ventilation, and air conditioning equipment, causing them to potentially fail when called upon to perform

their safety-related function.

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 one of the technical contacts

identified below or the appropriate project manager in the NRCs Office of Nuclear Reactor

Regulation (NRR).

/RA/
                                                William D. Beckner, Chief

Reactor Operations Branch

Division of Inspection Program Management

Office of Nuclear Reactor Regulation

Technical Contacts:      Robert G. Krsek, Region III            Jack W. Foster, NRR

(920) 388-3156                         (301) 415-3647 Email: rgk@nrc.gov                     Email: jwf@nrc.gov

John G. Lamb, NRR                      Steven M. Unikewicz, NRR

(301) 415-1446                         (301) 415-3819 Email: jgl1@nrc.gov                    Email: smu@nrc.gov

Attachment: List of Recently Issued NRC Information Notices

ML040770145 OFFICE     OES:IROB:DIPM Tech Editor               PM:PDIII-2     SC:PDIII:DLPM       EMEB

NAME       JWFoster           PGarrity             JGLamb         LRagahavan          SUnikewicz

DATE       03/17/2004         03/11/2004           03/17/2004     03/17/2004          03/18/2004 OFFICE     SC:EMEB            D:DE                OES:IROB:SC     C:IROB:DIPM

NAME       DTerao            RJBarrett            CJackson        WDBeckner

DATE       03/17/2004         03/19/2004          04/07/2004      04/07/2004

Attachment 1 LIST OF RECENTLY ISSUED

NRC INFORMATION NOTICES

_____________________________________________________________________________________
Information                                             Date of

Notice No.              Subject                         Issuance          Issued to

_____________________________________________________________________________________
2004-06           Loss of Feedwater Isokinetic         03/26/2004        All holders of operating licensees

Sampling Probes at Dresden                             for nuclear power reactors except

Units 2 and 3                                          those who have permanently

ceased operations and have

certified that fuel has been

permanently removed from the

reactor vessel.

2004-05           Spent Fuel Pool Leakage to           03/03/2004        All holders of operating licensees

Onsite Groundwater                                     for nuclear power reactors (except

those who have permanently

ceased operations and have

certified that fuel has been

permanently removed from the

reactor vessel) and for research

and test reactors, and all holders

of fuel storage licenses and

construction permits.

2004-04           Fuel Damage During Cleaning          02/24/2004        All holders of operating licenses

at a Foreign Pressurized Water                         for light-water reactors, except

Reactor                                                those who have permanently

ceased operations and have

certified that fuel has been

permanently removed from the

reactor.

2004-03           Radiation Exposures to               02/24/2004        All well-logging licensees.

Members of the Public in

Excess of Regulatory Limits

Caused by Failures to Perform

Appropriate Radiation Surveys

During Well-logging

Operations

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}}

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