ML20058N617
| ML20058N617 | |
| Person / Time | |
|---|---|
| Site: | Big Rock Point File:Consumers Energy icon.png |
| Issue date: | 10/11/1993 |
| From: | Donnelly P CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML20058N620 | List: |
| References | |
| NUDOCS 9310200067 | |
| Download: ML20058N617 (9) | |
Text
__
CORSUG1 BIS i
P0Wer "atrick = oaaa r Plant Manager POWERING MIEHIGAN'S PROGRESS Big Rock Pomt Nuclear Plent. 10269 05-31 North. Charlevoix. MI 49720 October 11, 1993 Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 DOCKET 50-155 - LICENSE DPR BIG ROCK POINT PLANT - ADDITIONAL FOLLOW-UP RESPONSE TO INSPECTION REPORT 92-019 On December 23, 1992, Consumers Power Company submitted a response to Inspection Report 92-019, which referred to a special Electrical Distribution System Functional Inspection (EDSFI) conducted on August 17 through September 22, 1992. The submittal provided a response to each of the Open and Unresolved Items described in the Inspection Report.
Since that submittal, the facility has been addressing commitments made during the course of the special inspection. This letter (with attachment) provides an update.
/7
//?7 +/
t c
/
i7nu Patrick M Donnelly Plant Manager CC: Administrator, Region III, USNRC NRC Resident Inspector - Big Rock Point i
ATTACHMENT 1500n9 9310200067 931011 5
/
PDR ADDCK 05000155 {?
/
0 PDR L
f A CAG ENE72GY COMPANY
.l
l t
t ATTACHMENT Consumers Power Company Big Rock Point Plant Docket 50-155 - License DPR-6 ADDITIONAL FOLLOW-UP RESPONSE TO INSPECTION REPORT 92-019 October 11, 1993
ATTACHMENT ADDITIONAL RESPONSE TO INSPECTION REPORT 92-012 Open Item 155/92019-01 Lack of a calculation to demonstrate that the 46 KV line could maintain adequate voltage levels during a design base accident (DBA) with the 2.4 KV voltage regulator out of service.
i December 23, 1992 Response As discussed in the Inspection Report, a preliminary calculation was performed i
during the inspection which concluded this mode of operation acceptable.
A formal load flow calculation will be performed and reviewed by offsite engineering personnel to document the acceptability of this configuration.
3 This effort should be completed by May 1, 1993. Within 60 days following completion of the analysis, operating procedures will be updated to advise operators that this mode of operation is acceptable.
Updated Response An Engineering Analysis, EA-ELEC-VOLT-012 Rev 0 [ Reference 1: Internal Correspondence LR93*008, From LReynolds to JRTilton dated April 16,1993],
was performed which resolved Open Item 92-019-01 by demonstrating that the 46 1
kv line can provide acceptable voltage levels at station power buses during a design basis accident (DBA) while the 2400 V voltage regulator is out of service.
Operating Procedure 50P 14, Substation [ Reference 2], has been revised to advise operators of this mode of operation. See sections 3.0.1 and 5.1.h.
l Open Item 155/92019-04 Addition of acceptance criteria to the Daily fuel Oil Report.
December 23, 1992 Response The Daily Fuel Oil Report has been revised to address this concern. The report now provides a level for each tank at which refuel is required. (A copy of the revised report was attached to the letter, and we considered all actions complete).
Updated Response No change.
Unresolved Item 155/92019-06A Calculations performed during the inspection concluded that the required NPSH for the diesel generator cooling water pump could be met at high flow rates providing significant lake level decrease or temperature increase did not occur. The Inspectors were concerned that the limits for lake level and temperature were not available to plant operators.
2 L
ATTACHMENT i
ADDITIONAL RESPONSE TO INSPECTION REPORT 92-012 1
December 23, 1992 Response As discussed in the report, Consumers Power agreed to issue an Operations Memo to advise plant operators on the potential loss of EDG cooling water pump NPSH due to lake level. This memo was issued on September 25, 1992 and a copy-(was attached) for information. As stated in the Operators Memo, this guidance will remain in effect until the issue is resolved or the information is incorporated into the operating procedures.
The reason that temperature monitoring was not included in the guidance is because enhancements are in progress to improve flow characteristics and monitoring of this piping. These enhancements will be completed prior to lake water temperature increasing due to summer temperature affects. Flow characteristic improvements will mitigate the effects of warmer water on the cooling capability of this system.
Updated Response The Emergency Diesel Generator suction cooling water piping was modified per Specification Change 92-026. This modification installed a new suction screen (with larger holes to avoid fouling concerns) and a new check valve with a lower flow resistance than the old one. As a result of this modification the cooling water flow calculation was reproduced to verify that there is-adequate cooling water with the new arrangement. The Engineering Analysis [ Reference 3]
demonstrates that the modifications have increased flow through the cooling water system and that the system will still meet the present administrative limits. Another modification has been planned to install an orifice in the discharge piping to reduce the flow approximately 70 gpm to allow for relaxation of the administrative limits now in place.
Operating Procedure T7-28 [ Reference 4] has been revised to change the acceptance criteria for suction pressure to less than or equal to I4" Hg vacuum. Also, an Operations Memo has been issued to declare the EDG inoperable at lake levels less than 578 feet [ Reference 5].
Unresolved item 155\\92019-06B The team was concerned that the suction pressure acceptance criteria identified in the weekly surveillance procedure was too high to assure proper operation of the cooling water system.
December 23, 1992 Response As discussed in the report, Consumers Power Company agreed to re-analyze the suction pressure acceptance for the surveillance procedure. This action is
. complete and a copy of the revised acceptance criteria was attached to the original letter.
Updated Response No change.
i
a L
ATTACHMENT.
1 i
ADDITIONAL RESPONSE TO INSPECTION REPORT 92-012 h
1 i
]
Unresolved Item 155\\92019-06C The team was concerned that suction screen cleaning was being postponed after i
suction pressures indicated potential plugging. Trending data.showed that maintenance orders were written when suction pressure fell outside.the i
expected range, but on occasion the work completion was not timely..
.l l
December 23, 1992 Response The surveillance procedure has been revised (a copy was attached to.the-l original letter) to require high priority to maintenance orders for' suction screen replacement. In addition, values are being assigned to minimum discharge pressure and maximum suction pressure to identify screen clogging and maintenance order generation. These values are being put in the i
surveillance procedure.
l 4
Updated Response The Maintenance department has responded per Internal Correspondence-RCS 93 i
[ Reference 6] that they will no longer delay cleaning / replacing suction screens when scheduling work. -The surveillance procedure has been revised to include minimum discharge pressure and maximum: suction pressure.
j Op_qp Item 155\\92-019-07 During the inspection, wiring discrepencies were discovered between the l
electrical design drawings and the as-built configuration of the EDG control panel s.
December 23, 1992 Response I
As stated in the inspection report, the observed discrepencies did not affect the operability of the circuits. Drawing changes have been initiated.
Walkdowns are part of the modification process and should identify any other
{
deficiencies which will be handled on a case-by case basis. Current
. surveillance testing insures equipment operability.
Updated Response i
l The wiring discrepancies were corrected by completing work orders to remove redundant jumpers that were not included on plant drawings. There was no need-to change.the plant drawings; the configuration was modified to reflect the drawing.
j i
Onen item 155/92019-08 The team was concerned that control of conduit and cable tray fill j
requirements was deficient and that licensee walkdowns identified some overfilled conduits that did not have a thermal analysis.
j
,a m
m.,_
...m.
4 4
ATTACHMENT ADDITIONAL RESPONSE TO INSPECTION REPORT 92-012 December 23, 1992 Response The electrical design specification (E-8) will be revised to incorporate conduit and cable tray sizing / fill instructions. The raceway schedule has been reviewed to identify which conduits / cable trays exceed these guidelines and evaluations are in progress. All safety-related overfills have been resolved and the remainder will be reviewed on a case-by-case basis. The target conletion date for the effort is December 1993, which allows time for waldowns in the 1993 Refueling Outage.
Updated Response The plant has established a program for calculating the fill requirements in a conduit or a cable 2. ray under plant drawing 0740A30008 [ Reference 7].
The Big Rock Point staff has concluded that verification of the fill limitations concerning the existing conduits or cable trays of equipment identified as safety-related is important to ensure plant operability.
Likewise, the existing conduits or cable trays that contain non safety-related circuits have demonstrated their ability to perform by virtue of the plant's 30 year operating cycle with no identified problems.
Based on the operating experience of the facility, this resolution to the conduit and cable tray overfill concerns seems to be the proper approach.
Open Item 155/92019-09 The team was concerned with the availability of design information to insure that installed fuse were properly selected and sized. Although an operability concern did not exist because the circuits have functioned when required, program improvements were warranted.
December 23, 1992 Response Although design information is not readily available for all fuses at Big Rock Point, it has been our philosophy to do only "like for like" replacements to insure configuration control. As discussed, in the Inspection Report, Big Rock Point personnel identified this concern just prior to the EDSFI from our review of inspection results at other facilities and are in the process of establishing a program. The program has a target completion date of December 1993, since walkdowns are required during the 1993 Refueling outage.
Updated Response Based on the successful operation of the control and power circuits that are protected with fuses, the licensee concludes that the proposed method of indexing along with the existing procedure (Volume 1, Procedure 3.2.1, Fuse Control Guidelines, step 5.3.2.w) [ Reference 8] for the replacement of a disabled fuse is the most prudent means for controlling the fuses at Big Rock Point.
i
r.
.h Pe-v i
,d 1
i l
l-REFERENCE 1 l
1 I
i
\\
i i
1 i
2 1
i
-""r=P w
D e
wy.-
e-.
aw+--
+-,
,.m, f
f APR 2 ' Rih To:
JRTilton, Big Rock Constuners Power From:
LReynolds, Palisadesb Company Date:
April 16, 1993
Subject:
Big Rock Point Electrical Internal Distribution System Functional Correspondence Inspection (EDSFI) cc KEYeager, Palisades, w/o attachment LR93*008 MDBourassa, Big Rock, w/o attachment File: PAG-28-10, w/o attachment This letter is regarding the Engineering Analysis in response to open item 92-019-01 (inspection step 3.1.1, reference 1) of the Big Rock Point Nuclear Plant's Electrical Distribution System Functional Inspection (Docket No. 50-155), conducted from August 17, 1992 through September 22, 1992.
An Engineering Analysis (EA-ELEC-VOLT-012 Rev 0) was performed which resolved open item 92-019-01 by demonstrating that the 46kv line can provide acceptable voltage levels at station power buses during a design basis accident (DBA) while the 2400V voltage regulator is out of service.
Attached is a copy of Engineering Analysis EA-ELEC-VOLT-012 Rev 0.
The minimum 46kv system voltage during a Loca and station power-loads fed via the 46kv system (138kv system feed unavailable and the 2400V voltage regulator out of service) is 0.952 per unit (43.8kv).
During a Loca condition with the 46kv system voltage at 0.952 per unit (43.Bkv) and the 2400V-voltage-regulator out of service, station power bus voltages are within the equipment limits.
The table below summarizes the worse case bus voltages and their voltage limits.
Loca Condition-Minimum 46kV System Voltage Bus Voltaces Bus Minimum Bus ReQulator O/S Voltace Limit 2400v 0.956 0.89 Bus 1A 0.924 0.90 Bus 2A 0.902 0.90 Bus 802 0.901 0.863 Bus 407 0.888 0.863 i
)
The table above indicates that the voltage level at Bus 2A is 0.902 per unit (433V), whereas the Bus 2A minimum voltage level is 0.90 per unit (432V).
Although the Bus 2A voltage level (0.902 pu) is near the bus minimum voltage limit (0. 90 pu),
equipment fed from this bus will still perform their intended function.
The conservative value assumed for the 2400V voltage regulator bypass switch impedance, yields conservative voltages in the simulation.
All bus voltage levels listed'in the table are above their minimum voltage limits.
Inspection step 3.1.4 of reference 1 pertains to an NRC 3
identified calculation weakness due to nonconservative data used in short circuit calculation DRS-110184-1 Rev 2.
The NRC team reviewed the calculation (DRS-110184-1 Rev 2) and concluded that the nonconservative data would not affect the calculation results and that the 2400v and 480V switchgear had sufficient short circuit current interrupting capability.
However, the Electrical Section of Electrical /I&C/ Computer Engineering of NECO at Palisades will revise calculation DRS-110184-1 Rev ? to incorporate conservative data such as:
1)
Voltage regulator minimum impedance 2)
The lowest transformer tap impedance 3)
Conductor temperature set at 25 degrees C j
Completion of the revised short circuit study is targeted for I
December 30, 1994.
)
l Reference 1:
Internal Correspondence Letter, from JRTilton (Big Rock) to KEYeager (Palisades), " Big Rock Point l
Electrical Distribution Safety Functional Inspection (EDSFI) " dated 2/19/93, File: JRT 93-14 l
1
,