ML18038B076
| ML18038B076 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 12/14/1994 |
| From: | Salas P TENNESSEE VALLEY AUTHORITY |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| IEB-93-003, IEB-93-3, NUDOCS 9412220133 | |
| Download: ML18038B076 (12) | |
Text
PRIORITY ACCELERATED RIDS PROCESSING REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)
ACCESSION NBR:9412220133 DOC.DATE: 94/12/14 NOTARIZED: YES DOCKET FACIL:50-260 Browns Ferry Nuclear Power Station, Unit 2, Tennessee 05000260 AUTH.NAME'UTHOR AFFILIATION SALAS,P.
Tennessee Valley Authority RECIP.NAME RECIPIENT AFFILIATION Document Control Branch (Document Control Desk)
SUBJECT:
Confirms that util has implemented hardware mod to ensure that plant Unit 2 RV water level sys of high functionality for long term operation. Installation occurred on 941115.W/
encl.
P DISTRIBUTION CODE:
IE41D COPIES RECEIVED:LTR ENCL SIZE:
TITLE: Bulletin 93-03:
BWR Reactor Pressure Vessel (BPV) Water Level Instrum R
NOTES:
RECIPIENT ID CODE/NAME NRR/DRPW INTERNAL: ~E CENTRE 01 NRR/DSSA/SRXB EXTERNAL: NRC PDR COPIES LTTR ENCL 1
1 1
1 2
2 1
1 RECIPIENT ID CODE/NAME WILLIAMS,J.
NRR/DRCH/HICB COPIES LTTR ENCL 1
1 1
1 Y'
N NJOTE TO ALL"RIDS" RECIPIENTS:
PLEASE HELP US TO REDUCE lVKSTE!CONTACT'I'IIE DOCL'CLIENT CONTROL DESK, ROONI PI -37 (EAT. 504-'2083 ) TO ELIXIINATE YOl.'R NA NIL FROll DISTRI8U'I'ION LIS'I'S I'OR DOC!.'NIEN'I'S YOL'ON"I'EI'.D!
TOTAL NUMBER OF COPIES REQUIRED:
LTTR 7
ENCL 7
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Tennessee Valley Authority. Post Office Box 2000, Decatur, Alabama 35609 December 14, 1994 U.S. Nuclear Regulatory Commission ATTN:
Document Control Desk Washington, D.C.
20555 Gentlemen:
In the Matter Of
)
Tennessee Valley Authority
)
Docket No. 50-260 BROWNS FERRY NUCLEAR PLANT (BFN)
UNIT 2 HARDWARE MODIFICATION COMPLETION AND DESCRIPTION IN RESPONSE TO BULLETIN 93-03'ESOLUTION OF ZSSUES RELATED TO REACTOR VESSEL WATER LEVEL INSTRUMENTATION IN BOILING WATER REACTORS The purpose of this letter is to confirm that TVA has implemented the hardware modification to ensure the BFN Unit 2 reactor vessel water level system is of high functionality for long term operation.
The hardware modification was installed during BFN's Unit 2 Cycle 7
refueling outage and completed on November 15, 1994.
The enclosure describes the hardware modification.
TVA considers this issue closed for BFN Unit 2.
There are no commitments contained in this letter. If you have any questions, please telephone me at (205) 729-2636.
Si lyr Pedro Salas Manager of Site Licensing Subscribed and swor to before me 1994.
Notary Public w
~al Enclosure cc:
See page 2
94i2220i33 94i2i4 PDR ADOt K 05000260 PDR
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U. S..Nuclear Regulatory Commission Page 2
December 14, 1994 Enclosure cc (Enclosure):
Mr..Stewart D. Ebneter Regional Administrator U.S. Nuclear Regulatory Commission Region II, Suite 2900 101 Marietta Street, NW Atlanta, Georgia 30323 Mr. Mark S. Lesser, Section Chief U. S. Nuclear Regulatory Commission Region II 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323 NRC Resident Inspector Browns Ferry Nuclear Plant Route 12, Box 637
- Athens, Alabama 35611 Mr. J.
F. Williams, Project Manager U.S. Nuclear Regulatory Commission One White Flint, North 11555 Rockville Pike Rockville, Maryland 20852
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FIGURE I
BFN-UNIT 2 BACKFILL MOD 85-764 FE 5-76 FLOW METER NEEDLE VALVES CONDENSING POTS LI FEEOWATER PI CONTROL SYSTEM I
I I
CRO CHARGING H20 (TYP OF 4)
FILTER MAIN STEAM 658 INCHES TO FW LEVEL CONTROL SEL I
I J
I I
I 5 I 7 INCHES 236A A
k LT LT LT LT LT 3-I85 3-208C 3-2080 3-203 3-2030 LT
-60 I
I PT PT 3-6I NORMAL RANGE EMERGENCY RANGE 235A 366 INCOMES LT LT IT 3-560 3-58D 3-468
'I PIS PT 3-228 3"22D
-79 3-748 I
I I
I I
I I
I QOG PR PI PI LT 3-59 3-79
-74 3-62A LT LR 3-6 3-62 QLI POST ACCIDENT RANGE PT 3-204D WT PUMP l6 LOWER TAP
'35 INCHES 283 RPV INSTRUMENTATION (TYP OF 2) k RPS-SCRAM
- ECCS INITIATION
II
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ENCLOSURE TENNESSEE VALLEY AUTHORITY BROWNS FERRY NUCLEAR PLANT (BFN)
UNIT 2 NRC BULLETIN 93-03 DESCRIPTION OF HARDWARE MODIFICATION PURPOSE AND BACKGROUND This enclosure provides a description of the BFN unit 2 hardware modification performed in accordance with NRC Bulletin 93-03 (Reference. 1).
NRC Bulletin 93-03 requested that licensees complete hardware modifications to address the potential for level instrumentation system errors due to the presence of noncondensible gases in level instrumentation reference legs.
The Bulletin requested that hardware modifications be implemented at the next cold shutdown beginning after July 30, 1993.
Bulletin 93-03 further requested that licensees submit a report "within 30 days of completion of the requested hardware modifications."
The report should describe the modification and confirm completion.
BFN Unit 2 was shutdown for its Cycle 7 refueling outage on October 1,
1994.
This was the first cold shutdown after July 30, 1993.
In accordance with TVA's commitment made in response to Bulletin 93-03 (Reference 2), the hardware modification was installed during the Unit 2 Cycle 7
refueling outage and completed on November 15, 1994.
TVA installed a "Back-fill"'ystem which provides a feed from the Control Rod Drive (CRD) system to each of the four Reactor Water Level Instrumentation reference legs.
The flow injected from the CRD system will serve to purge noncondensible gases from the reference legs during normal operation and to prevent gas-induced level errors during postulated rapid depressurization events.
DESCRIPTION OF BFN UNIT 2 HARDWARE MODIFICATION The BFN Unit 2 design for the continuous backfill system hardware modification consists of tubing, filters, and valves necessary to route the process fluid from the CRD system to the reactor pressure vessel (RPV) instrument reference leg headers.
Process fluid flows from the CRD system into the reactor pressure vessel due to the higher CRD system pressure.
The continuous flow eliminates transportation of noncondensible gases from the condensing chamber into the reference leg.
Cl
There are four backfill injection lines, one for each of the four condensing chambers.
Each of the backfill lines contain one seven-micron (nominal) filter.
The filters are used to filter any impurities that could clog or affect the needle valves used to regulate the injection flow rates.
There are also provisions to bypass the filters to allow replacement of the filters.
On the. RPV instrument panels there are two needle valves '(per backfill line) used to regulate the backfi;ll flow rates'rom 0.006 gpm to 0.'02 gpm.
Flow rates are'onitored by local indication.
Downstream of the flow control station are two qualified seismic category I check valves in series to prevent a
loss of water inventory from the condensate pots if CRD pressure drops below reactor vessel pressure.
Figure 1 is included for reference.
REFERENCES NRC Bulletin 93-03 dated May 28, 1993,. Resolution of Issues Related to Reactor Vessel Water Level Instrumentation in BWRs.
2.
TVA letter to NRC dated July 30,
- 1993, Browns Ferry Nuclear Plant (BFN), Response to NRC Bulletin 93-,03, Resolution of Issues Related to Reactor Vessel Water Level Instrumentation in Boiling Water Reactors (BWRs).
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