ML20081J815
| ML20081J815 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 03/23/1995 |
| From: | Denton R BALTIMORE GAS & ELECTRIC CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9503280193 | |
| Download: ML20081J815 (5) | |
Text
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.,I' Rostar E. DENTON Baltimore Gas and Electric Company Calvert Cliffs Nuclear Power Plant Vice President Nuclear Energy 1650 Calvert Cliffs Parkway Lusby, Maryland 20657 410 586-2200 Ext.4455 Local 410 260-4455 Baltimore l
l l
March 23,1995 U. S. Nuclear Regulatory Comnussion Washington, DC 20555 ATTENTION:
Document Control Desk
SUBJECT:
Calvert Cliffs Nuclear Power Plant Unit No.1; Docket No. 50-317 Request for Temporary Relief from ASME Boiler & Pressure Vessel Code Section XI Reauirement IAW-5250 Baltimore Gas and Electric Company requests temporary relief from ASME Boiler & Pressure Vessel Code Section XI (1983 Edition) requirement IAW-5250, as allowed by 10 CFR 50.55a(a)(3). We specifically request permission to delay the repair of the half-coupling located on the bottom of the common saltwater discharge header in the Unit I senice water pump room until no later than the next Unit I refueling outage (spring 1996), and to accept the as-is condition of the piping for continued use.
Compliance with the requirement for repair prior to use would result in hardship without a compensatory quality or safety improvement.
I.
Component for Which Reliefis Reauested Temporary reliefis requested for the half-coupling located on the bottom of the common saltwater discharge header. A small leak has been discovered in the body of the half-coupling. 'Ihe Saltwater System provides the cooling medium for the component cooling and senice water heat exchangers, and ECCS pump room air coolers. The component cooling and service water s>m are designed to remove heat from various auxiliary systems. The ECCS pump room air coolers I
provide additional cooling to the ECCS pump rooms during ECCS pump operation. The saltwater piping in this area is a Class 3 component under the requirements of Section XI and Regulatory Guide 1.26.
II.
Code Reauirements for Which Reliefis Reauested ASME Boiler & Pressure Vessel Code Section XI (1983 edition, with summer 1985 addenda),
requirement IAW-5250, states:
9503280193 950323 PDR ADOCK 05000317 N
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.. ; 5 " Document Control Desk March 23,1995 Page 2
"(a) He source ofleakages detected during the conduct of a s>1 tem pressure test shall be located and evaluated by the Owner for corrective measures as follows:
... (2) repairs or replacements of cowponents shall be performed in accordance with IAW-4000 or IAW-7000, respectively."
III.
Frs=d Alternative The common saltwater discharge header has been evaluated and the structural integrity of the saltwater pipe is unaffected by the leakage through the half-coupling. Additionally, the structural integrity of the saltwater pipe is unaffected by the complete loss of the half-coupling. Considering the duration and extent of a repair and the low likelihood of a complete loss of the half coupling, we consider deferring the repair to be the appropriate course of action from a safety perspective.
We propose to perform periodic visual examinations to ensure that the leakage from the half-coupling has not significantly increased. This provides appropriate safety assurance until the next outage of sufficient duration, but no later than Unit l's next scheduled refueling outage (spring 1996), at which time a code repair will be made.
IV.
Suonertine Information A.
Scauence of Events During a routine monthly walkdown on March 14,1995, esidence of scepage from a half-coupling on the common saltwater discharge header for Unit I was found. This evidence consisted of a brown stain on the freshly painted saltwater piping in the area of the half-coupling. Drops of water were observed (about two per minute). On March 14,1995,an ultrasonic examination in the area of the half-coupling was performed. He piping in the area of the half-coupling was found to exceed the required minimum wall thickness. An Issue Report was written, and on March 14,1995, the structural integrity of the common saltwater discharge header was confirmed.
Technical Specification Action Statement 3.4.10, " Structural Integrity of ASME Code Class 1, 2 and 3 Components," was entered.
An initial operability assessment for the common saltwater discharge header was performed by evaluating the leakage from the Saltwater System if the half-coupling should shear off. He affected half-coupling is located in piping that is downstream of the saltwater /senice water heat exchangers and would not affect the ability of the heat exchangers to remove heat. In addition, the c531uation showed that there is adequate margin in the capacity of the Saltwater System so that the postulated leak would not affect the ability of the Saltwater System to perform its safety function.
- ,. - A h ControlDesk March 23,1995 Page 3 Based on this ev+-% an imtial detennination was made that the Unit J Sahwater System is able to perform its safety function. Therefore, the system is determined to be operable. However, because of the identified leakage in the half-x-f=1 we mnnin b the Technical Specification Action Statement 3.4.10, " Structural Integrity of ASME Code Class 1,2 and 3 C:#f=== " 1his Action Statement does not restrict =*i==1 power operation; however, it does require that the affected E---i-:=" have its structural integrity restored or be isolated The structural integrity of the Saltwater System has been -
evaluated using the methodology in ANSI B31.1. 'Ihis evaluation has determined that the structural integnty of the pipe is unaffected by the loss of the half-coupling.
1 B.
Analysis l_
'Ihe piping around the leakmg half-coupling was examined ultrasonically. The pipe wall l
thickness at each examination location was found to be significantly greater than the l
minimum allowable wall tu=
Stress analyses were performed for the half-coupling l
connection. These analyses imhcate that the weld for the half-coupling is loaded to less
.l than 5% of the allowable stresses. Although the flaw in the half-coupling cannot be j
completely characterized, this provides assurance that a catastrophic failure is highly l
unlikely. Subsequent analyses were performed assuming a complete failure of the half-I coupling.
i C.
Safety Sinnificance
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i The operability of the Saltwater System ensures that sufficient cooling capacity is i
available for continued operation of equipment during normal and accident conditions. To ensure that the system's function was au4 a total failure of the half-coupling was assumed and the subsequent leakage was calculated. At the design pressure for the system, the-maximum leakage from the failed half-coupling was evaluated to be approximately 389 gpm. 'Ihe senice water room has been analyzed for a floodmg rate of l
447 gpm. Because the postulated floodmg rate fan the failed half coupling is less than the allowed flooding rate, the failure of the half-coupling has no safety unpact on the senice water room. Additionally, due to the location of the failed half-coupling, it was determmed that spray from this leak would not affect any Motor Control Centers or vital components.
D.
Code Reauirement Psfesunce Imnact
'Ihe repair of the half-coupling on the saltwater pipe requires that the affected section of pipe be drained and opened To drain the pipe and gain access to the weld requires that the Unit be brought to Mode 5 and the Saltwater System discharged to the bay by an alternate path. We estimate that the replacement of the half-coupling could be accomplished within approximately five days.
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March 23,1995 Page 4 During Modes 1 through 4, two iP* saltwater loops must be operable. Both the No. II subsystem and the No.12 subsystem join into a common discharge header in the service water pump room. It is a half-coupling attached to this common discharge that is leaking To repair the half-coupling, Unit 1 must be placed in Mode 5 to allow us to isolate this common piping. In Mode 5, an alternate flow path to the bay would be used.
This flow path uses both saltwater subsystems to create a single sahwater cooling loop.
'Ihis does not meet the requirements of Technical Specification 3.7.5 concerning iW of the Saltwater System.
'Ihis section of pipe will be examiwd azd.mimi during the next outage of sufficient duration, but no later than the next refueling outage. 'Ihat outage is scheduled for spring 1996. To perform a repair which will require a Unit shutdown is a hardship without a compensating increase in the level of quality and safety.
i V.
Comnensatory Actions We will perform periodic visual examinations to verify that the leakage from the half-coupling has not significantly increased. In addition, ultrasonic examinations of the area surrounding the half-coupling will be performed once every six months.
VI.
Implementation Schedule A.
Visual examination during operator rounds to monitor leakage from the half-coupling -
Daily B.
Ultrasonic examination of the area around the half coupling - Every six months C.
Repair or repbe - Next outage of sufficient duration, but no later than the spring 1996 refueling outage SAFETY COMMITTEE REVIEW
'Ihe proposed relief request has been reviewed by our Plant Operations and Safety Review Committee and they concluded that compliance with IAW-5250 would result in a hardship without a co.r.pcr.satory improvement in quality or safety.
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i Document ControlDesk March 23,1995 Page5
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i Should you have questions regarding this matter, we will be pleased to discuss them with you.
Very truly yours, i
?
RED / PSF / dim cc:
D. A. Brune, Esquire J. E. Silberg, Esquire L. B. Marsh, NRC D. G. Mcdonald, Jr., NRC T. T. Martin, NRC P. R. Wilson, NRC R. I..McLean, DNR J. H. Walter, PSC
.