ML20115A597
| ML20115A597 | |
| Person / Time | |
|---|---|
| Site: | Cooper  |
| Issue date: | 06/28/1996 |
| From: | Mueller J NEBRASKA PUBLIC POWER DISTRICT |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| RTR-NUREG-0619, RTR-NUREG-619 NLS960095, TAC-M82258, NUDOCS 9607080210 | |
| Download: ML20115A597 (6) | |
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. COOPER NUCLEAR STATK)N PD. 00X 98. SROWNVILLE. NEBRA9KA 00321
. Nebraska Public Power District
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NLS960095 June 28,1996 t
U.S. Nuclear Regulatory Commission
. Attention: Document Control Desk -
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Washington, D.C. 20555-0001 4
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Subject:
Feedwater Nozzle and Control Rod Drive Return Line Report
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Cooper Nuclear Station, NRC Docket No. 50-298, License No. DPR-46 I -
References:
1)
NUREG-0619, published November 1980, "BWR Feedwater Nozzle and Control Rod Drive Return Line Nozzle Cracking" l
1 2)
Letter to G. R. Horn (NPPD) from R. B. Bevan (USNRC), dated February 13,1992, " Cooper Nuclear Station - Staff Acceptance of.
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Fracture Mechanics Evaluation of Flaw Indications (TAC No. M82258)"
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- Gentlemen:
t In accordance with Reference 1, the Nebraska Public Power District (District) is submitting to the Nuclear Regulatory Commission (NRC) an examination summary report regarding the feedwater nozzles at Cooper Nuclear Station (CNS).' The attached report covers past examinations up to and including the 1995 Fall refueling outage. No reportable indications were r
identified during the ultrasonic examinations of the feedwater nozzles. There have not been any.
changes to systems, procedures, or plant operation that would change the feedwater temperature L
or flow since the last report.' Based on the leakage monitoring results, the District has determined that there has been no feedwater to nozzle bypass leakage in excess of the 0.3 gpm reporting threshold established in Reference 2 since the last report.
If you have any questions or require any additional information, please contact me.
Sincerely, A
JJ J hn H. Muclier Site Manager
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Atte.chments I
9607090210.960620 f
PDR ADOCK 05000298
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.P DR.
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US. Nuclear Rcgulatory Commission
. June 28,1996
- Page 2 of 2 cc:
Senior Project Manager USNRC.- NRR Project Directorate IV-1 Senior Resident inspector
- USNRC - Cooper Nuclear Station Regional Administrator USNRC'- Region IV NPG Distribution A
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Attachment to NLS960095 Page1of3 NUREG-0619 FEEDWATER NOZZLE EXAMINATION
SUMMARY
REPORT l
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l NLS960095 1
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Cooper Nuclear Station NRC Docket No. 50-298 y
License No. DPR I
- System Background The feedwater system consists of two half capacity cascading-type heater strings with a shared
- bypass line also rated at half capacity..The preheated feedwater is routed to two turbine driven feedwater pumps, The pump discharge lines are then routed through a flow control station ~and
. then discharged to the reactor vessel through foer feedwater spargers. Throughout most of a plam startup the feedwater flow control valves are operated in an automatic mode to' maintain constant reactor vessel level and a stable feedwater flow.- Although the heaters are in service during startup, normal feedwater heating does not commence until extraction steam is established i
4after the turbine is placed in service. Due to these plant characteristics and operational methods,
- the feedwater nozzles experience a maximum temperature variance ofless than 10 F between feedwater loops during power operation and an average temperature difference ofless than 5 F
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( between feedwater loops during startup.
History During the Fall 1977 refueling outage, the control rod drive (CRD) System was tested for proper
. operation with the return line valved out of service. Satisfactory results from that test allowed the cutting and capping of the CRD return line at the reactor vessel nozzle. Dye penetrant inspections of the retum line nozzle and surrounding vessel wall revealed no crack indications.
- During the Spring 1980 refueling outage, the interference-fit feedwater spargers were removed,
. the nozzle cladding was removed, and the nozzles were inspected. Triple-thermal sleeve, double
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piston ring spargers were installed. No changes were made to the feedwater control system.
Based on a ratio of reactor water cleanup (RWCU) flow to feedwater flow of 1 to 100, reroutmg of the RWCU system was not considered applicable to Cooper Nuclear Station. No other system changes were made.
During 1981, a CRD System return flow capability test was performed in accordance with paragraph 8.2(4) of NUREG-0619. With two CRD pumps in operation, a flow capacity in excess
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of 160 gpm was achieved at a reactor pressure above 1000 psig. With one CRD pump m operation, a flow capacity of 140 gpm was achieved at a reactor pressure of 990 psig.
i During the Fall 1991 refueling outage, automated ultrasonic examination and supplemental monitoring programs were implemented in lieu of the nozzle dye penetrant examination required by NUREG-0619 (
Reference:
USNRC letter to G. R. Horn, dated October 2,1991, " Review of
.NPPD's Request Regarding Feedwater Nozzle Examination Methods," TAC No. 79612).
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Attachment to NLS960095 Page 3 of 3 Cooper Nuclear Station NRC Docket No. 50-298 License No. DPR-46 1996 NUREG-0619 Feedwater Nozzle Examination Summary OUTAGE DATE SU/SD Cycles EXAM TYPE RESULTS From Last Since Initial Exam Startup Fall 1980 0
102* Since 1974 UT, PT, VT Spargers replaced. Nozzle baseline NDE; Sparger baseline VT Spring 1982 9 Since 1980 111*
UT, VT No indications Fall 1983 4 Since 1982 115*
VT No Indications Spring 1984 4 Since 1983 119*
VT No indications Fall 1986 8 Since 1984 127*
UT,VT No Indications Spring 1988 10 Since 1986 137*
VT No indications Spring 1989 4 Since 1988 141*
UT, VT No indications Fall 1991 7 Since 1989 148 UT,VT No indications Spring 1993 4 Since 1991 152 VT No indications Fall 1995 7 Since 1993 159 UT No indications
- These numbers have been corrected based on internal review of startup/ shutdown cycles and represent a conservative estimate.
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ATTACHMENT LIST OF NRC COMMITMENTS 3
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' Correspondence'No: NLS960095
..The'following table identifies those actions committed to by the District in this
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document. Any other actions discussed in the submittal represent intended or 1
planned actions by the District. They are described to the NRC for the NRC's information and are not regulatory commitments. Please notify the Licensing Manager i
i Lat Cooper Nuclear Station of any questions regarding this document or any associated-regulatory commitments.
COMMITTED DATE i
COMMITMENT OR OUTAGE t
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N/A one 4
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l PROCEDURE NUMBER 0.42 l
REVISION NUMBER 1 l
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