IR 05000259/1995062
| ML18038B578 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 12/07/1995 |
| From: | Fredrickson P, Kellogg P NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | |
| Shared Package | |
| ML18038B577 | List: |
| References | |
| 50-259-95-62, 50-260-95-62, 50-296-95-62, NUDOCS 9512180380 | |
| Download: ML18038B578 (16) | |
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,UNITED STATES NUCLEAR REGULATORY COMMISSION
REGION II
101 MARIETTASTREET, N.W., SUITE 2900 ATLANTA,GEORGIA 303234199 Report Nos.
50-259/95-62, 50-260/95-62, and 50-296/95-62 Licensee:
Tennessee Valley Authority 6N 38A Lookout Place 1101 Market Street Chattanooga, TN 37402-2801 Docket Nos.
50-259, 50-260 and 50-296 License Nos.
.and DPR-68 Facili.ty Name:
Browns Ferry Nuclear Power Station Units 1, 2, and
P Inspection Cond ted:
October 30 - November 3, 1995 Inspector:
Pa m
ea er D te igne Accompanying Personn
- L. King, Reactor Inspector L. Melle
, Reactor Inspector Approved by:
Paul E. Fredrickson, Chief Special Inspection Branch Division of Reactor Safety
/< 7 D te Signed SUMMARY Scope:
A service water system self-assessment inspection was conducted on October 30 to November 3, 1995, to determine the adequacy of the licensee's self assessment and status of corrective.actions.
Two of the primary objectives, of this followup inspection were to (1) perform an independent overview evaluation of the service water systems and (2)'o evaluate the quality and depth of the licensee's self-assessment.
Results:
With regard to both objectives, the licensee's self assessment was thorough.
Service water engineers and operations personnel were determined to have a
very good knowledge of the systems.
The items identified for correction had been assigned for action and =actions were being carried out.
The service water systems appeared to;be in good mechanical condition and appropriate
.maintenance was being performed.
Enclosure 95/ Qf80380 0500025/
pDR ADOCt pD
REPORT DETAILS
.Persons contacted Licensee Personnel
- T. Abney, Unit 3 Nuclear Assurance and Licensing, Recovery Manager
- J. Cory, Radiation Controls Manager
- C. Davis, Corporate Licensing
- T. Dexter, Training Manager
- S. Wetzel, Acting Compliance Manager J.
Maddox, Maintenance and Modifications Manager
- J. Dollar, Operations H. Crisler, Outage Manager T. Golston, Component Materials and Technical Support Program Manager
- J. Grafton, Chemistry Technical Support Supervisor
- F. Loscalzo, Mechanical
.Engineer
- J. HcCarthy, Mechanical/Nuclear Lead
- G'. HcConnell, Maintenance
- G. Pierce, Technical Support Manager
- G. Preston, Plant Manager
- J. Sabados, Chemistry Superintendent T. Shaw, Balance of Plant Systems Supervisor, Technical Support
- P. Salas, Licensing, Manager
- T. Shriver, Nuclear Assurance and Licensing Manager G. Waldrep, IR8A Manager
- J. Wallace, Compliance Engineer
- H. Williams, Engineering
.and Maintenance Hanager
- J. White, Senior Outage Hanager Other licensee employees contacted included engineers, technicians, operators and. office personnel.
U. S. Nuclear Regulatory Commission
- R. Husser, Resident Inspector Background and Objectives During the period, April 17, 1995 to Hay 12, 1995, a Service Water SWSOPI self assessment was performed at the Browns Ferry Nuclear Plant by a TVA team and contract individuals.
The assessment team utilized NRC Temporary Inspection 2515/118, Revision 1 and industry experience gained from previously performed inspecti'ons of service water systems as a basis for the assessment.
The assessment identified five strengths and six areas of weakness.
The strengths noted in the assessment were as follows: the systems were well documented with design calculations,,
the large number of RHRSW pumps provided operational flexibility, the level of knowledge of operations personnel was high, the color coded valve tag convention was a configuration control strength, and the plant material condition was good.
The six areas of weakness were as follows:
ik
heat exchanger inspection results
.were not always maintained to provide
,a trending program, check valves between the EECW and
+he new chemical injection system were not in the IST program,
".ome nor-unservative assumptions were used in the HVAC design analysis, discrepancies existed between operations and engineering as to the functions for alarm and indications, and transient materials were found without the proper reviews and/or controls in place.
On June 23, 1995, the licensee issued the final SWSOPI self assessment report.
During the period, October 30, 1995 through November 3, 1995, a three-member NRC team performed a followup inspection.
The focus of this inspection was. to review the licensee's final assessment report, to ascertain the progress made in addressing assessment findings, and to perform an abbreviated and.independent review of the service water systems.
Service Water Hydraulic Analysis The inspector reviewed the BFNP hydraulic analysis of the EECW and RHRSW systems.
The analysis modeled the hydrauli'c configuration at the time of the test and demonstrated that there was a substantial excess of both EECW and RHRSW system flow.
The hydraulic model was force fit to the conditions at the time of the test by adjusting piping resistance values.
There was no attempt to verify that the model was capable of predicting flows in alignments other than the tested configuration.
This limited the usefulness of the model in predicting system response in other configurations.
The inspector concluded, and the licensee concurred, that the hydraulic model, while appropriate for the EECW and RHRSW flow test, needed further modifications before it could be used as the basis for operability determinations or other safety-related purposes.
Ultrasonic Flow Heasurements During the EECW and RHRSW system walkdown, the inspector noted in the mechanical equipment rooms that the mounting location for the ultrasonic flow detector was not in accordance with the manufacturer's recommendation.
This was six pipe diameters downstream of a transition and four pipe diameters upstream of a transition.
The flow measurement took place in an area that was about two pipe diameters from a piping transition and in a region of flow that could have been disturbed by this transition.
The inspector discussed the operation of the ultrasonic detectors with the technicians that used the devices, reviewed the testing requirements, the vendors manual, and the purpose for the surveillance test.
Because of the location of the measurement, the licensee and the inspector concluded that there was not enough information available to quantify the loop uncertainty for the measurement of the flow to the control bay chiller IA and IB.
This measurement of flow was taken during the flow balance, but due to the excess flow the loop uncertainties had little impac lN
During.the performance of SI-3.2.4, EECW Check Valve Test, the control t ay chiller flow measurement was taken just downstream of 'the piping
,<<
'ing to valve 1-67-673.
However, the purp)se of the SI was to demonstrate that the EECW check valves opened.
Whi1e. there were quantitative limits in the SI, they were met and the loop uncertainty did not cause significant problems.
The licensee stated that they would verify that any flow measurements that were made with ultrasonic measurement devices which required quantifiable results, would be reviewed.
Disposition of Self Assessment Findings The inspectors reviewed the SWSOPI team observations to determine the present disposition of the observations identified by the team.
The inspectors also reviewed the test procedures and test data that was used to determine operability of the EECW system and the RHRSW system.
A review was also made of the test deficiencies and changes made as a
result of the testing.
A review of the test data for the EECW system showed that minimum flows were attainable at all essential components.
The RHRSW test proved that minimum required service water flows could be delivered to Unit 3.
Testing also verified that for the combined operation of Units 2 and 3, the functional requirements for safe shutdown of Unit 3 could be met.
The test deficiencies identified did not affect test acceptance criteria and had no impact on the restart test program test requirements.
During initial testing of the RHRSW system for Unit 3 on August 26, 1995, an unusually 'high differential pressure was observed on the C and D heat exchangers.
Inspection revealed that scale had deposited on the inlet tube sheet.
The scale was attributed to the higher flow rates achieved due to new piping, heat exchanger cleaning and replacement during the outage and new heat exchanger outlet valves that are less restrictive.
The heat exchanger heads on the remaining heat exchangers were removed and inspected, and where necessary, were cleaned.
Subsequent to heat exchanger cleaning, testing was performed on all four heat exchangers to ensure that the flow rates were acceptable.
The inspectors reviewed tube plugging on al-1 safety related heat exchangers that used EECW and RHRSW for cooling.
All heat exchangers were well within acceptable limits for tube plugging.
The inspectors determined that all of the observations made by the SWSOPI team had'een.
responded to and actions had been taken to satisfy the team's concerns.
The licensee relies on inspection of coolers to determine their operability for accident condition heat removal.
In addition the operability testing assures that minimum required flows can
'be met under worst case condition i
The SWSOPI team had identified the fact that the air side of the RHR and CS pump room coolers are not inspected and cleaned on some periodicity to assure air side 'heat transfer capability is maintained.
A followup by the inspectors showed that all of the coolers had been cleaned and the preventive maintenance procedures for chemical cleaning of the water side are planned to be expanded to include cleaning of the air side.
The licensee planned to test room coolers in the future with test apparatus that was developed at another TVA facility.
The test will attempt to calculate fouling factors.
If the test data is meaningful, the licensee will investigate using the methodology in the future to determine operability of the room coolers.
The inspectors also reviewed the surveillance procedures that determined check valve operability for check valves installed on the EECW system.
The test proved operability in the direction of flow.
Internal EDG Room Flooding PER BFPER 940337 dated May 17, 1995, was issued to address the concern of a moderate energy pipe break in the die'sel generator rooms which could cause internal flooding.
Check valves O-CKV-40-3, O-CKV-40-519, and 0-CKV-40-520 serve the purpose of allowing water out of the Units 1/2 and
EDG buildings; and also preventing water from a design basis flood from entering the building.
This protects the EDGs and maintains them operable during either a postulated crack in the EECW, headers inside these buildings or the design basis flood.
Since the valves remain closed unless water is flowing out, the failure mode for the design basis flood is passive.
In both
.EDG buildings there are sump pumps whose capacity exceeds the leakage of a postulated crack in the EECW piping.
The maximum postulated flood rate for the EDG buildings develops from the EECW pipe break.
This is postulated to be 234 gpm.
The sump pumps are rated at 400 gpm 8 40 ft. total head.
Therefore the single failure criteria for Units 1/2 and
EDG building sump pumps does not apply.
Concerning internal flooding, the check valves may not be able to pass the required flow to maintain 12" or less of flood level in the EDG buildings.
However there is a high level alarm in both EDG building sumps.
This would have notified operations of an abnormal condition in the EDG buildings.
At which point operations personnel would be dispatched and compensatory actions could be taken such as opening the EDG room doors or starting the sump pumps.
Check Valves Not In IST Program PER BFPER 950531 dated May 4, 1995, was initiated to disposition pressure boundary isolation check valves on the chemical injection system to the EECW/RHRSW.
Valves 0-CKV-50-521 through 691 were recently installed (1994)
by DCN W27000A and, at that time, it was determined
jgi i~,
that a test program for the valves was not a requirement.,
Chemical injection occurs for only 15 minutes a quarter and therefore the isolation valves ai e in fact normally closed.
~sing this process, the manual isolation valves would be the ASHE Section XI boundary, and the check valves would provide redundancy to meet single failure criteria.
This would not require that the first check valves past the isolation valves be placed in the IST Program, but they would need to be inspected in the BFNP Check Valve Inspection Program.
The second check valves past the isolation valves would not be needed to assure single failure criteria is met and therefore would not be required to be in a formal test/inspection program.
Check valves 0-CKV-50-1017 through 24 were installed by ECN E-0-P165 in 1990.
The valves were never placed in the IST or Check Valve Inspection program.
It was thought that the isolation valves, as above, were normally closed.
The assumption that the isolation valves were normally closed was an error.
The licensee therefore added these valves to the IST Program.
The list of components exempted from testing based on design input information was reviewed.
No additional items were identified during this review.
Procedures HSI-O-OOO-CKV001, Haintaining Check Valves, Revision 5, dated July 19, 1995, has been revised to include the appropriate check valves.
EECW FLows To EDGs ECN P0658 dated Harch 21, 1983, modified the cooling water piping to the diesels to provide for series flow through the heat exchanger vice parallel flow as was the previous configuration.
This, according to Engineering, will double the EECW flow to each heat exchanger and will result in a lower head loss in the new configuration.
The piping was also changed from carbon steel to stainless steel.
Calculation BWP 830315101 provided a basis for changing the EECW flow to the EDG heat exchangers from parallel flow to series flow.
This modification will increase the flow through the heat exchangers and will provide for increased heat removal.
Calculation B90 88 1010212 reanalyzed the heat exchanger configuration for different input temperatures and number of plugged tubes.
The required EECW flow through the heat exchangers was reduced to 450 gpm.
A Followup on Previously Identified Items a 0 (Closed)
IFI 94-11-02, TI 2515/099 BWR Power Oscillations, IEB 88-70, and Generic Letter 94-02 These items concerned the BWR hydraulic instabilities that can be experienced in areas of high power and low recirculation flow.
The licensee has conducted cycle specific training for both Units 2 and 3.
The lesson plan (OPL171.007 Revision 13) discusses several events where BWRs had entered the regions of high power and low recirculation flows.
This lesson plan was utilized during July 1995 in cycle 13 training.
The actions to be taken included
scramming the reactor if the recircul'ation pumps trip or if the areas cannot be exited by increasing flow o repositioning rods.
The lesson plan appeared to be comprehensive and covered all aspects of the hydraulic instabilities.
Based upon the review of the above lesson plan and interviews with operators, this item is closed.
b.
C.
(Closed) Unit Differences Training This item concerned the difference that will exist when Unit 3 is restarted.
The inspector reviewed Lesson Plan OPL173.036, Unit Differences.
This lesson plan was also utilized during the current training cycle.
The lesson plan was comprehensive and covers the physical differences between the units as well as the differences in Technical Specifications and setpoints.
While the lesson plan was comprehensive, it could be confusing in that most of the setpoint differences identified will be resolved prior to Unit 3 restart.
The lesson plan was taught during this cycle because the systems had not yet been declared operational.
The training department has planned additional realtime training in this area prior to restart.
Based upon the lesson plan reviewed above and operator interviews, this item is closed.
(Closed)
IFI 95-23-01 SWSOPI Self Assessment Findings Disposition This item was opened to track disposition of the SWSOPI self assessment fin~ings.
This item is closed based upon the reviews note in paragraphs 2 thorough 8 of this report.
10.
Conclusions Two of the primary objectives of this follow-up inspection were (1) to perform an independent overview evaluation of the service water systems and (2) to evaluate the quality and depth of the licensee's self-assessment.
With regard to these objectives, the team determined that the licensee's self-assessment was very thorough.
The items identified had been assigned for action and actions were being carried out.
The service water systems appeared to be in good mechanical condition and appropriate maintenance was being performed.
11.
Exit Interview The team conducted an exit meeting on November 3, 1995, at the Browns Ferry Nuclear Plant to discuss the major areas reviewed during the inspection, the strengths and weaknesses observed, and the inspection results.
The licensee did identify documents or processes reviewed by the inspectors as proprietary.
The proprietary material is not contained in this report.
There were no dissenting comments at the exit meetin il
]pi
12.
Acronyms and Initialisms.
ASHE BFNP CS DCN ECN EDG EECW HVAC IST NRC PER SI SWSOPI RHR RHRSW American Society of Mechanical Engineers Browns Ferry Nuclear Plant
. ~
Containment Spray Design Change Notice Engineering Change Notice Emergency Diesel Generator Emergency Equipment Cooling Water Heating, Ventilation, 8 Air Conditioning Inservice Test Nuclear Regulatory Commission Problem Evaluation Report Surveillance Instruction Service Water System Operational Performance Inspection Residual
.Heat Removal Residual Heat Removal Service Water
f 0