ML20141H334
| ML20141H334 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 07/01/1997 |
| From: | Katz P BALTIMORE GAS & ELECTRIC CO. |
| To: | Miller H NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| References | |
| NUDOCS 9707220352 | |
| Download: ML20141H334 (5) | |
Text
_ _ _ _ _ - _ _
PETEn E. KATZ Baltimore Gas and Electric Company Plant General Manager Calvert Cliffs Nuclear Power Plant i
Calvert Cliffs Nuclear Power Plant 1650 Calvert Cliffs Parkway Lusby, Maryland 20657 410 495-4101 July 1,1997 U. S. Nuclear Regulatory Commission Region I 475 Allendale Road King of Prussia, PA 19406 ATTENTION:
Mr. H. J. Miller, Regional Administrator
SUBJECT:
Calvert Cliffs Nuclear Power Plant Unit Nos.1 & 2; Docket Nos. 50-317 & 50-318 Main Steam Header Radiation Monitors -- Soecial Reoort The attached special report is submitted in accordance with Calvert Cliffs Unit I and Unit 2 Technical Specification 3.3.3.1. The report concerns the inoperability of Unit I and Unit 2 Main Steam Header Radiation Monitors for a period in excess of seven days.
Should you have questions regarding this matter, we will be pleased to discuss them with you.
Very tru y yours, gL
/,
PEK/RCG/bjd
/
Attachment g
cc:
Document Control Desk, NRC Director, Project Directorate I-1, NRC R. S. Fleishman, Esquire Resident Inspector, NRC J. E. Silberg, Esquire R.1. McLean, DNR A. W. Dromerick, NRC J. H. Walter, PSC 9707220352 970701 PDR ADOCK 05000317 S
PDR l
cong~qg lE!\\MlIQ\\\\\\]IIll]IllyllIlll
ATTACHMENT (1)
MAIN STEAM HEADER RADIATION MONITORS - SPECIAL REPORT Baltimore Gas and Electric Company submits this Special Report concerning inoperable Nos. I1,12,21 and 22 Main Steam Header Radiation Monitors as required by Unit I and Unit 2 Technical Specifications 3.3.3.1, Table 3.3-6, item 2.b.ii.
ACTION TAKEN Numbers 21 and 22 Main Steam Header Radiation Monitors were removed from OPERABLE status on June 6,1997 at approximately 1210 for No. 21 Main Steam Header Radiation Monitor and at approximately 1700 for No. 22 Main Steam Header Radiation Monitor due to failures of the checksource tests during the performance of the monthly channel functional tests required by Unit 2 Technical Specification 3.3.3.1, Table 4.3-3, Item 2.b.ii.
Numbers 21 and 22 Main Steam Header Radiation Monitors were installed per an approved modification during the Unit 21997 refueling outage. Following the installation, engineering test procedures were performed which included the performance of checksource tests. The monitors satisfactorily passed all requirements of the engineering test procedures [ performed with Unit 2 in Mode 5 and Main Steam Isolation Valve (MSIV) Room ambient temperature of approximately 90 F] and were placed in OPERABLE status in late-May 1997.
During the performance of the first monthly channel functional test on June 6,1997, Nos. 21 and 22 Main Steam Header Radiation Monitors failed to respond during a checksource test. Troubleshooting on No. 21 Main Steam Header Radiation Monitor determined that the checksource was properly aligned with respect to the collimating hole during the checksource test period; however, following reveral checksource tests, no response from the detector was noted. Further troubleshooting found that no response was seen when the checksource was placed directly on the detector. The checksource was then placed directly on a personnel contamination gamma detector and the source strength was determined to be satisfactory. Several checksource tests were then performed on No. 22 Main Steam Header Radiation Monitors and no response from the detector was seen.
During evaluation of the troubleshooting results, it was suspected that a generic problem with detector performance existed. On June 10, 1997, checksource tests on the Unit 1 Nos. I1 and 12 Main Steam Header Radiation Monitors were performed to confirm that a generic problem existed. Both Nos. I1 and 12 Mam Steam Header Radiation Monitors failed to respond to a checksource test and were removed from OPERABLE status at approximately 0730 on June 10, 1997. (Note: The Unit 1 Main Steam Header Radiation Monitors were replaced in early 1997 per an approved modification. They were satisfactorily tested in accordance with similar engineering test procedures as those performed on the Unit 2 Main Steam Header Radiation Monitors with Unit 1 in Mode 1 and MSIV room ambient temperature of approximately 110 F-120 F and placed in OPERABLE status in early-May 1997. The Unit 1 Main Steam Header Radiation Monitors had previously passed its first monthly channel functional tests required by Unit 1 Technical Specification 3.3.3.1, Table 4.3-3, Item 2.b.ii earlier in June 1997.
The MSIV room ambient temperature was still approximately 110 F-120 F.)
Following confirmation that a generic detector performance problem existed, additioual troubleshooting, using No. 21 Main Steam Radiation Monitor, determined the detectors were sensitive to elevated temperatures. Main Steam Isolation Valve Room ambient temperature was measured at approximately 135 F.
A contact temperature reading on No. 21 Main Steam Header Radiation Monitor detector i
6 A'ITACHMENT (1)
MAIN STEAM HEADER RADIATION MONITORS - SPECIAL REPORT measured approximately 155 F. The detector was removed from the MSIV room and allowed to cool to approximately 80 F and was returned to the MSIV room. A checksource test was immediately performed and was satisfactorj. However, subsequent checksource tests, performed at approximately 3 to 5 minute intervals, showed a d: grading detector performance.
Secondary button source checks were performed on No. 21 Main Steam Header Radiation Monitor detector after cooling the detector to approximately 80 F, with the detector at MSIV room ambient temperature of 135 F, and with the detector at approximately 155 F. Degraded detector performance was noted at elevated temperatures.
Vendor documentation states that the detector should be capable of operating satisfactorily over a temperature range of-30 C to +90 C (-22 F to +194 F). Vendor environmental test data appeared to substantiate the published detector operating temperature range. However, based upon the results of the troubleshooting and the vendor specifications, it was concluded that the detectors were not operating as expected over the spaified temperature range.
The detectors and associated pre-amplifiers were returned to the vendor for confirmatory testing and modification, if necessary. The vendor confirmed that the detectors were not operating as expected over the specified temperature range and that the originally supplied environmental test data was incomplete.
A proposed modification to the detector temperature compensation circuit has been temporarily implemented and is undergoing initial vendor testing.
4 EFFECT ON OPERATION Unit 2 Technical Specification 3.3.3.1 Action Statement (30) was entered when Nos. 21 and 22 Main Steam Header Radiation Monitors were removed from service. In accordance with this Action Statement and our Accidental Radioactivity Release Monitoring and Sampling Methods procedure (ERPIP-821),
alternate sampling methods were implemented. The inoperability of Nos. 21 and 22 Main Steam Header Radiation Monitor has not affected Unit 2 operation.
Unit 1 Technical Specification 3.3.3.1 Action Statement (30) was entered when Nos. I1 and 12 Main Steam Header Radiation Monitors were removed from service, in accordance with this Action Statement and our Accidental Radioactivity Release Mcnitoring and Sampling Methods procedure (ERPIP-821),
alternate sampling methods were implemented. The inoperability of Nos. I1 and 12 Main Steam Header Radiation Monitor has not affected Unit 1 operation.
1 CAUSES OF INOPERABILITY Numbers 11,12,21, and 22 Main Steam Radiation Monitors were declared not OPERABLE due to the failure of the detectors to respond to a checksource. It was found that the detectors failed to operate as expected over the specified temperature range. The cause of the inoperability is inadequate vendor design of the detector temperature compensation circuit.
2
4 f
ATTACIIMENT (1)
MAIN STEAM HCADER RADIATION MONITORS - SPECIAL REPORT PLANS AND SCHEDULES FOR RESTORING THE SYSTEM TO OPERABLE STATUS Additional vendor testing of the proposed modification is continuing. Following the completion of this testing and Baltimore Gas and Electric Company acceptance of the results, formal factory acceptance testing of the modified detectors will occur. Upon satisfactory completion of the factory acceptance testing, site acceptance testing per approved engineering test procedures will occur. It should be noted that this testing will occur with the units operating and the MSIV room at elevated temperatures where the problem with the detector response was first identified. Following completion of the site acceptance tests, the Main Steam Header Radiation Monitors will be returned to OPERABLE status. The estimated completion date for the return of the Main Steam Header Radiation Monitors to OPERABLE is August 31,1997.
l 1
3 i
-