05000280/LER-1998-007, :on 980330,radiation Monitors Were Declared Inoperable.Caused by Change in Operating Temperature Range. Preplanned Alternate Method of Monitoring Was Initiated IAW TS Table 3.7-6
| ML18152B795 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 04/29/1998 |
| From: | Christian D VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| To: | |
| Shared Package | |
| ML18152B794 | List: |
| References | |
| LER-98-007, LER-98-7, NUDOCS 9805070120 | |
| Download: ML18152B795 (4) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(viii) |
| 2801998007R00 - NRC Website | |
text
.. UCLEAR REGULATORY COMMISSION APPROVED BY 0MB NO. 3150-0104 (4-95)
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LICENSEE EVENT REPORT (LER)
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(See reverse for required number of digits/characters for each block)
U.S. NUCLEAR REGUlATORY COMMISSION. WASHINGTON, DC 2055>0001, AND TO THE PAPERWORK REDUCTION PROJECT (3150--010,4),
OFFICE OF MANAGEMENT AND
- BUDGET, WASHINGTON, DC 20503.
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DOCKET NUMBER (2)
PAGE(3)
SURRY POWER STATION, Unit 1 05000-280 1 OF4 TITLE (4)
Radiation Monitors Inoperable Due to Change in Operating Temperature Range EVENT DATE (5)
LER NUMBER (6)
REPORT DATE (7)
OTHER FACILITIES INVOLVED (8)
DAV VEAR VEAR SEQUENTIAL REVISION MONTH DAV VEAR FACILITY NAME OOCUMENT NUMBER l'KNlH Surry Unit 2 05000-281 NUMBER NUMBER 03 30 1998 1998
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00 04 29 1998 FACILITY NAME DOCUMENT NUMBER 05000-OPERATING
- THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check one or more) (11)
MODE(9)
N 20.2201(b) 20.2203(a)(2)(v)
- 50. 73(a)(2)(i) 50.73(a)(2)(viii)
POWER 20.2203(8)(1) 20.2203(a)(3)(i)
- 50. 73(a)(2)(ii)
- 50. 73(a)(2)(x)
LEVEL (10) 0%
20.2203(a)(2)(i) 20.2203(a)(3)(ii)
- 50. 73(a)(2)(iii) 73.71 20.2203(a)(2)(ii) 20.2203(8)(4)
- 50. 73(a)(2)(1v)
X OTHER 20.2203(a)(2)(iii) 50.36(c)(1)
- 50. 73(a)(2)(v)
Specify in Abstract below 20C2203(a)(2)(1v) 50.36(c)(2)
- 50. 73(a)(2)(vii) or in NRC Fonn 366A LICENSEE CONTACT FOR THIS LER (12)
NAME I TELEPHONE NUMBER (Include Area Code)
D. A. Christian, Site Vice-President (757) 365-2000 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13)
CAUSE
SYSTEM CXMODIT MANUFACTURER REPORTABLE
CAUSE
SYSTEM COMPONENT MANUFACTURER REPORTABLE TONPRDS TONPRDS SUPPL!;Jl1,l:1'4TAL REPORT EXPECTED (14)
EXPECTED MONTH DAY YEAR.
I :f::s. complete EXPE~TI:~:::,~~ION ~ATE)..
Ix 1-NO SUBMISSION DATE ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines) (16)
On March 30, 1998, with Unit 1 at Intermediate Shutdown and Unit 2 at 100% power, the ambient temperature of the detector enclosures for the Unit 2 main steam line effluent high range radiation monitors was noted to be above the maximum value at which the vendor currently certifies operation. The subject monitors were declared inoperable at 18:20 and the preplanned alternate method of monitoring was initiated in accordance with Technical Specifications (TS) Table 3.7-6. An extensive evaluation of the effects of higher ambient temperature on the radiation monitors was performed~ The evaluation concluded that although elevated temperatures may decrease reliability, the subject monitors remained capable of performing their function as specified in the Emergency Plan Implementing Procedures. Based on this evaluation, the monitors were returned to an operable status on April 28, 1998. This event occurred due to a change made by the vendor that resulted in a change in the design operating temperature range for the radiation monitor detectors. To prevent recurrence, detector ion chamber circuit boards that are capable of operating at the higher ambient temperatures of the detector enclosures will be installed. This Special Report is being submitted in accordance with TS Table 3.7-6 because the subject radiation monitors were not returned to an operable status within seven days.
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~ ~" ~~"'" ~ I Ul'(T 1.,UMMISSION LICENSEE EVENT REPORT (LER)
TEXT CONTINUATION FACILITY NAME (1)
Surry Power Station Unit 1 DOCKET 05000-280 TEXT (If more space is required, use additional copies of NRC Form 366A) (17) 1.0 DESCRIPTION OF THE EVENT LER NUMBER (6)
PAGE (3)
YEAR I SEQUENTIAL I REVISION NUMBER NUMBER 98
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00 2 OF 4 On March 30, 1998, with Unit 1 at Intermediate Shutdown and Unit 2 at 100% power, Engineering noted that the ambient temperature of the detector enclosures for the Unit 2 main steam line effluent high range radiation monitors [EIIS-IL,MON] was above the maximum value at which the vendor currently certifies operation (i.e., less than or equal to 120 degrees F). Operations conservatively declared the Unit 1 and 2 main steam line effluent high range radiation monitors (1-MS-RM-124, 1-MS-RM-125, 1-MS-RM-126, 2-MS-RM-224, 2-MS-RM-225, and 2-MS-RM-226) inoperable at 18:20 and the preplanned alternate method of monitoring was initiated in accordance with Technical Specifications (TS) Table 3. 7-6.
During the subsequent four week period, Engineering perfo~ed an extensive evaluation of the effects of higher ambient temperature (i.e., greater than 120 degrees F) on the subject radiation monitors. The evaluation included a review of the results of vendor testing, as weli as the failure history of Surry's monitors. The evaluation concluded that although elevated temperatures may decrease reliability, the subject monitors remained capable of performing theit function as specified in the Emergency Plan Implementing Procedures. -Based on the Engineering evaluation, 1-MS-RM-124; 1-MS-RM-125, 1-MS-RM-126 2-MS-RM-224 2-MS-RM;.225 and 2-MS-RM-226 were returned to an operable status on April 28, 1998.
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A temporary blower was installed in accordance with station procedures to reduce the ambient temperature of the detector en~losures. This int~rim measure will enhance the reliability of the monitors until the ultimate corrective actions are implemented.
This Special Report is being submitted in accordance with TS Table 3. 7-6 because the Unit 1 and 2 main steam line effluent high range radiation monitors were not returned to
. an operable status within seven days.
2.0
SIGNIFICANT SAFETY CONSEQUENCES AND IMPLICATIONS
The main steam line effluent high range radiation monitors are designed to measure radioactivity, resulting from primary to secondary systems leakage, that may be released through the main steam safety or atmospheric dump valves [EIIS-SB,RVJ following an accident. These radiation monitors are nonsafety-related and do not initiate any automatic equipment actuations.
I (4-95)
LICENSEE EVENT REPORT (LER)
TEXT CONTINUATION FACILITY ~ME (1)
Surry Power Station Unit 1 DOCKET 05000-280 YEAR SEQUENTIAL NUMBER 98
- - 007-PAGE (3) 30F4 TEXT (If more space is required, use additional copies of NRC Form 366A) (17) 2.0 SIGNIFICANT SAFETY CONSEQUENCES AND IMPLICATIONS (Continued)
When the subject monitors were declared inoperable, the preplanned alternate method of monitoring was initiated, utilizing the condenser air ejector radiation monitor. This monitor and the steam generator blowdown sample line radiation monitor provide alternate indications of primary to secondary systems leakage. In addition, Health Physics personnel were notified that the monitors were out of service and that off-site monitoring may be necessary in the event of a radioactive release.
These compensatory measures provide an acceptable alternate method of satisfying the design functions of the main steam line effluent high range radiation monitors. Therefore, this event resulted in no safety consequences or significant implications and the health and safety of tt1e public were not affected at any time.
3.0
CAUSE
This event occurred due to a change made by the vendor that resulted in a change in the design operating temperature range for the radiation monitor detectors [EIIS-IL,DEll The detectors were originally designed to operate at temperatures up to 167 degrees F.
However, due to the age of the design and resulting unavailability of exact replacement parts, the g~t~tgy9r\\9hamber segment of the printed circuit ass*embly is no longer qualified to perform at the originally specified design temperature. The overall _effect of this change in the operating qualification was recently evaluated and confirmed by the vendor.
When the temperature at the detector enclosures was found to be above 120 degrees F, the subject radiation monitors were conservatively declared to be inoperable, although there was no indication of unsatisfactory operation.
4.0 IMMEDIATE CORRECTIVE ACTION(S) 1-MS-RM-124, 1-MS-RM-125, 1-MS-RM-126, 2-MS-RM-224, 2-MS-RM-225, and 2-MS-RM-226 were declared inoperable on March 30, 1997, at 18:20, and the preplai:,ned alternate method of monitoring was initiated in accordance with TS Table 3.7-6.
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(4-95)
LICENSEE EVENT REPORT (LER)
TEXT CONTINUATION FA<;ILITY NAME (1).
DOCKET YEAR SEQUENTIAL NUMBER Surry Power Station Unit 1 05000-280 98
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PAGE (3) 40F4 TEXT {If more space is required, use additional copies of NRC Form 366A) (17) 5.0
ADDITIONAL CORRECTIVE ACTIONS
Engineering performed an extensive evaluation to determine the effects of higher ambient temperature (i.e., greater than 120 degrees F) on the main steam line effluent high range radiation monitors. The evaluation concluded that the subject monitors remained capable of performing their function as specified in the Emergency Plan Implementing Procedures.
- Based on the Engineering evaluation, 1-MS-RM-124, 1-MS-RM-125, 1-MS-RM-126,
- 2-MS-RM-224, 2-MS-RM-225, and 2-MS-RM-226 were returned to an operable status on April 28, 1998.
- A temporary blower was installed in accordance with station procedures to reduce the ambient temperature of the detector enclosures and thereby enhance the reliability of the*
subject monitors.
6.0 ACTIONS TO PREVENT RECURRENCE Engineering is procuring replacement detector ion chamber printed circuiJ boards that are capable of operating at the higher ambient temperature of the detector enclosures. The new circuit baards=s.are scheduled to be available by July 1998, and will be installed
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thereafter.
7.0
SIMILAR EVENTS
Special Report 50-281/97"'.002-01, "Main Steam High Range Radiation Monitor Inoperable Due.to Equipment Failure" 8.0 MANUFACTURER/MODEL NUMBER Manufacturer:
Nuclear Research Corporation Model Number: TA 600