ML20028G972
| ML20028G972 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 10/01/1990 |
| From: | Creel G BALTIMORE GAS & ELECTRIC CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9010050016 | |
| Download: ML20028G972 (5) | |
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B ALTIMORE -
GAS AND-ELECTRIC -
1 CdARLES CENTER e P.O. BOX 1475
- BALTIMORE, MARYLAND 21203 1475'
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1 GroRoc C. CRttL.
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October 1,1990 -
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- I U. S. Nuclear Regulatory Commission Washington,DC 20555
' ATTENTION:
Document Control Desk
SUBJECT:
Calvert Cliffs Nuclear Power Plant Unit Nos.1 & 2; Docket Nos. 50-317 & 50-318 3
Combined Insocction Report No. 50-317/90-17 and 50 318N0-15
REFERENCES:
-(a)-
Letter from Mr. Jacque P. Durr (NRC) to Mr. G. C. Creel (BG&E),
dated August 27,1990, same subject Gentlemen:
Reference (a) requested that we provide the corrective actions to prevent recurrence of the weiding deficiencies discussed in the subject Inspection = Report. Reference (a[also requested that' we.
.i provide our strategy to prevent the. clogging problem in the Saltwater Coohng System. Enclosure (1) provides our response to these requests.
Should you have any further questions regar' ding this matter, we will b6 pleased to discuss them with you.
m Very truly yours, 7
' GCC/CDS/bjd.
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D. A. Brune, Esquire J. E. Silberg, Esquire R. A. Capra, NRC -
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D. G. Mcdonald, Jr., NRC T. T. Martin, NRC 1
L E. Nicholson, NRC
' R. I. McLean, DNR
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. ENCLOSURE (1J RESPONSE TO NRC INSPECTION REPORT 50 317/90-17:50-318!90-15 The cover letter for combined Inspection Report 50-317/90-17 and 50-318/90-15 re(Juested that we
-l provide the corrective actions to prevent recurrence of the discussed welding deficiencies and our strategy to prevent the clogging problems in the Saltwater Cooling System. Our responses to those requests are given below.
I.
WELDING DEFICIENCIES As described in the Inspection Report, two ba ic weioing deficiencies were identified by Calvert Cliffs personnel.
The deficiencies involved; (a) limited accessibility welder qualifications and (b) undersized fillet welds.
Limited Accessibility Welder Cualification Five welders made limited access & tids vat did not have up to date qualifications for limited accessibility welding in accordance with Regulatory Guide 1.71. The event was due to the failure of welding supervisors to venfy that up to date specialized weld qualifications existed
'q for the welders prior to performing the limited access welds.
As reflected in the Inspection Report, a3
- ek.crs involved have had their weld qualifications validated through a review of previoue vkid Authorization Travelers (WATS) and actual limited access testing. The welders involved demonstrated proficiency in producing quality -
welds in limited access performance tesu during their urst attempt. Based on the above, the lin.ited accessibility welds that the five widers produced have been deemed acceptable.
To prevent recurrence we are taking the following corrective actions:
1.
This issue will be highlighted during the next scheduled session of Welding Coordinator training.
2.
Procedure 6-WPP-CC 6.003 " Weld Program," will be changed to clarify the requirements for documenting of welder qualification status.
U 3.
The WAT form will be revised to include a check-off for limited access welds and other selected specialized weld qualification variables included in ASME Section IX.
The checklist review will be required to be performed by the welding supervisor within his responsibility of assigning qualified welders to jobs.
I:
l Undersized Fillet Welds The issue of undersized fillet welds involved the discovery of 16 undersized welds in a group of 26 welds representing several fillet sizes. Investigation found that the incident was due to weld examiners using rulers rather than more accurate fillet weld gauges to measure the 16 undersized welds. It was concluded that this was an isolated incident with only two of twelve o
L weld examiners having used a ruler rather than a gage.
- All of the undersized welds were reworked by adding weld filler material. The reworked l;
welds were then dimensionally checked and liquid penetrant inspected. The personcel 1
h invohud in the event have been appropriately disciplined.
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ENCLOSURE (1)
RESPONSE TO NRCINSPECTION REPORT 50 317/90 17:50 318/90 15 1
The importance of using proper wcld gages for visual inspections was emphasized at a recent Non-Destructive Examination Unit meeting. To reinforce this discussion,~ a note will be i
added to the appropriate Visual Testing Procedure indicating that proper weld measuring equipment shall be used on welds.
In order to correct an incorrect impression created by the Inspection Report, Quality Control inspectors are not considered " weld examiners" by our internal policy or procedures. Weld examination is done by our Materials Engineering and Analysis Unit (MEAU). Weld examiners tc trained and qualified in accordance with MEAU programs. However, Quality Control (Quality Verification in our organization) does perform periodic independent verification of welding and Non Destructive Examination (NDE) activitics.
11.
SALTWATER COOLING SYSTEM CLOGGING PROllLEM Biofouling in the Saltwater-System presents a threat to the proper operation of the Component Cooiing and Semcc Water Heat Exchangers and the ECCS Pump Room Coolers. We currently have no.adication that biofouling has had any effects on,the f Component Cooling Heat Exchangers. Our strategy for addressing Saltwater System biofouling concerns is a multifaceted approach which includes:
1.
Reducing the severity of biofouling by removing existing growth end preventing the introduction of new growth; 2.
Monitoring performance of the heat exchangers to ensure they are capable of performing their design function; 3.
Minimizing time that Saltwater System components are out of service for cleaning; ti
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- and, 4.
Trending and responding to changes in required cleaning frequency.
The details ofimplementing each facet of this program are discussed below.
1.-
- Reducine the Severity of the Biofouline:
i Flushine and Cleanine of the Saltwater System:
The first step in reducing the severity of biofouling was to remove existing marine growth in the intake structure and Saltwater System piping to the maximum extent
- possible. This was accomplished by draining, cleaning, and flushing portions of the Saltwater System.
Ll Improved Oncration of the Chlorination System:
The re infiltration of marine growth into the system following the cleaning is being neduced by improved ' operation of the chlorination system. A Facility Change i
Request (FCR) has been initiated to enhnnce the long-term reliability of this system.
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' ENCLOSURE (1)
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RESPONSE TO NRCINSPECTION REPORT
$0 317/9017: 30-318/9015 Periodic Cleanine of the System:
Despite improvements in the operation of the chlorination system, some marine growth is expected to accumulate in f ne Saltwater System piping over the long-term.
To prevent accumulation to the enent which could cause excessive clogging that presents a threat to the reliable operation of the Saltwater System,.the mtake structures will be cleaned periodically based on the results of the system fouling monitoring program described below.
v.
Saltwater System Chances to Reduce Infiltration of Marine Growth:
As reflected in the Inspection Report, we continue to improve the Saltwater Inlet Traveling Screen System with a sptem that has been found to be more effective.
j Fouling of the Emergency Core Cooling System (ECCS) Pump Room Coolers is l<
expected to be substantially reduced by the partial installation of FCR 85-085. The a
modification is expected to significantly reduce the amount of fouling of the ECCS.
Pump Room Coolers by relocating the suction connection for the coolers to the side of the Saltwater Syste: Seaders instead of the bottom.
2.
Monitorine the Pe.formance of the Heat Exchanners:
Periodic Moni:orine of Service Water Heat Exchancer Fouline Fact,r:
Service Water Heat Exchanger performance capabilitics are a function of the Chesapeake Bay (Saltwater) temperature and the extent of fouling.of the heat exchangers. This relationship is quantified by the heat exchanger's fouling factor.
The actual fouling factor is being calculated and compared to the existing bay temperature to ensure cleaning before the heat exchangers are no longer capable of meeting their design requirements.
ECCS Pumn Room Cooler Performance Testine:
The approach currently planned to verify the effectiveness of FCR 85-085 includce performance of post-modification testing and short-term performance tests. This will melude a short run after a debris causing event and a longer continuous run. An engineering analysis will be performed an the test results to demonstrate that near-term operation is safe. Appropriate performance data will be used to trend the effectiveness of the modificatien over the Icng-term.
3.
Minimizine Time that Heat Exchancers are Out of Service for Clenninc:
The increased use of our chlorination system will, over the long-term, reduce the frequency of heat exchenger fouling and thus reduce the frequency at which they y
need to be cleaned.- Changes to the procedure used to clean the Service Water Heat
- Exchangers have helped to reduce cleaning time from about 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> to about 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />.
4.
Trendine and Respondine to Chances in Reauired Cleanine Freauetev:
A high rate of fouling of the Service Water Heat Exchangers will result in reduced availability of the Saltwater System while the heat exchangers are being cleaned 'Ihis q
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.Jf-ENCLOSURE W.
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- RESPONSE TO NRC INSPECTION REPORT -
50-317/90-17:50-318/90-15 increases the potential that a Saltwater System train will be out of senice when called upon at the initiation of a design basis accident. A probabilistic risk ass-ssment has been performed to ascertain the risk associated with taking heat exchangers out of service for cleaning.-
The results of long term trending efforts will enable us to better anticipate required cleaning frequency and avoid reaching critical levels of fouling of heat exchangers in the future.
Additional actions to assure reliable iong-term operation of our Saltwater System are currently under development and will be submitted in our response to Generic Ixtter 89-13.
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