ML20059C766
| ML20059C766 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 08/19/1993 |
| From: | Rueger G PACIFIC GAS & ELECTRIC CO. |
| To: | |
| References | |
| OLA-2-I-MFP-089, OLA-2-I-MFP-89, NUDOCS 9401060077 | |
| Download: ML20059C766 (4) | |
Text
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Pacific Gas and Electric Company 77 Bere 5: ee:
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- 1 March 30, 1992 PG&E Letter No. DCL-92-071 U.S. Nuclear Regulatory Comission ATTN: Document Control Desk
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Washington, D.C.
20555 Re:
Docket No. 50-323, OL-DPR-82 Diablo Canyon Unit 2 Reply to Notice of Violation in NRC Inspection Report 50-275/92-01 and 50-323/92-01 Gentlemen:
NRC InipetM56'R76 ert 50-275/92-01 and 323/92-01, dated F e r rr287'T992,77costained a Noticargfriiolatten citing one Severity Level'IV violation regarding a reactor cavity sump wide range level channel that was inoperable for a period of time greater than the seven days allowed by Technical Specification 3.3.3.6, Action a.
PG&E's response to the Notice of Violation is enclosed.
Sincerely,
/[' *v G^W11,dt 2
7 regory H. Rueger cc:
Ann P. Hodgdon John B. Hartin g7 m,,gg gyyy Philip J. Morrill na w ijn Q m a m h& //
Harry Rood ne Howard J. Wong
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PG&E Letter No. DCL-92-071 i
187323 ENCLOSURE REPLY TO NOTICE OF VIOLATION IN NRC INSPECTION REPORT 50-275/92-01 AND 50-323/92-01 On February 28, 1992, as part of NRC Inspection Report 50-275/92-01 and 50-323/92-01, NRC Region V issued a Notice of Violation citing one Severity i
Level IV violation for Diablo Canyon Power Plant (DCPP) Unit 2.
The statement of violation and PG&E's response follow.
STATEMENT OF VIOLATION Technical Specification 3.3.3.6 requires that both reactor cavity sump wide range level cha1nels be operable in Modes 1 (Power Operation), 2 (Startup), and 3 (Hot Standby).
Technical Spacifications Action Statement 3.3.3.6,a requires i
that an inoperable channel be returned to serv f ce within i
seven days.
Contrary to the above, from October 15, until October 22, 1991, one of two reactor cavity sump wide range level channels was inoperable in Modes 2 and 3, for a period time of greater than seven days.
This is a Severity Level IV violation (Supplement I),
applicable to Unit 2.
REASON FOR THE VIOLATION IF A.MITTED, Op BASIS FOR DISPlTTING THE VIOLATION
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n PG&E acknowledges the violation.
On August 21, 1990, during performance of Surveillance Tr t Procedure (STP)
-l I-1B, " Routine Daily Checks Required by Licenses," operators identified a i
potential problem with the safety parameter display system (SPDS) critical safety function (CSF) path for containment. The problem was identified because the CSF path was flashing blue on the SPDS display screen. As i
discussed in Licensee Event Report (LER) 2-90-010, containment wide range sump level channels 942A and 943A were not declared inoperable until November 6, 1990, because the operators and I&C personnel involved did not understand that i
the blue flashing path meant that the channels supplying data to SPDS for that logic path were not operable.
Channel 942A failed low on October 10, 1991. The operators did not identify this failure during the performance of STP I-ID, ' Routine Monthly Checks Required by Licenses," or STP I-lC,
- Modes 1, 2, and 3 Weekly Checklist,"
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because the difference between the normal indicated level on the recorder and 1
I the failed low indicated level is no more than 1/16 inches. Ona-sixteenth of an inch is approximately the error that can be induced due to chart paper alignment on the recorder.
10225/85K l
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s 187323 The Technical Review Group (TRG) investigating the August 1990 containment wide range sump level channel 942A and 943A failures determined that since the blue flashing path had been identified during a control room routine daily surveillance (STP I-18), the root cause of the failure to identify and correct the problem was a failure to understand the meaning of the blue flashing path on the SPDS display.
As corrective actions for the August 1990 event, the TRG required that applicable operations and I&C personnel receive training on the meaning of the blue flashing path. The TRG discussed the need to revise STP I-18, but concluded that the existing channel checks, in conjunction with additional training on the SPDS, would be st.lMcient to (nsure equipment availability.
Between November 1990 and October 1991, there have been no failures of channel 943A and only 4 failures of channel 942A. None of the failures during this time period exceeded the 7-day Technical Specification (TS) action statement.
CORRECTIVE STEPS TAKEN AND RESULTS ACHIEVED On October 22, 1991, technicians performing investigative maintenance on channel 942A believed the cause of the problem to be a loose fuse. When the power fuses were re-installed, the channel was verified to be functioning normally. The channel was declared operable and was returned to service.
STP I-1B was revised on November 15, 1991, because the corrective action for the 1990 event did not prevent recurrence. This procedure revision added a daily check for indications of channel problems and listed the actions to be taken when channel problems were identified.
In addition, information plaques were installed on the SPDS display panels describing the SPDS signals for a channel problem.
Since the procedure revision has been in effect, the 7 day action statement of TS 3.3.3.6 has not been exceeded.
In addition, subsequent to the 1991 event, I&C personnel reviewed other control room indicators and determined that no other STP l-1B channel checks J
needed to be enhanced.
CORRECTIVE STEPS THAT WILL BE TAKEN TO AVOID FURTHER VIOLATIONS As discussed in LER 2-91-010, investigative actions are continuing in an i
attempt to locate the cause of the failures on channel 942A.
If a root cause i
is determined for the channel 942A failures, the root cause and applicable l
corrective actions will be reported in a revision to LER 2-91-010.
The revision of STP I-1B provides an adequate compensating measure that alerts the operators to failures in sufficient time to repair the channel and return it to service without exceeding the 7-day action statement of TS 3.3.3.6.
t Additional training is being provided to operators to increase sensitivity to these failures. These corrective actions are believed to be sufficient to prevent exceeding the 7-day action statement of TS 3.3.3.6.
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I A memo will be issued to applicable personnel describing this event and the importance of considering measures for monitoring equipment performance during the period while the root cause investigation is being completed.
DATE WHEN FULL COMPLIANCE WILL BE ACHIEVED Full compliance with TS 3.3.3.6 was achieved on October 22, 1991, when reactor cavity sump wide range level channel 94ZA was declared operable and returned to service.
The licensed operator training will be completed by May 31, 1992.
The memo describing the event will be issued by April 30, 1992.
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