ML20056E461
| ML20056E461 | |
| Person / Time | |
|---|---|
| Site: | Vermont Yankee File:NorthStar Vermont Yankee icon.png |
| Issue date: | 08/19/1993 |
| From: | Pelletier J VERMONT YANKEE NUCLEAR POWER CORP. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| BVY-93-86, NUDOCS 9308240087 | |
| Download: ML20056E461 (3) | |
Text
l VERMONT YANKEE i
NUCLEAR POWER CORPORATION xx Ferry Road, Brattleboro, VT 05301-7002 M
ENGINE RING OFFICE MO f/ AtN STRE E T fio' T ON f/ A 01740 Wo 779 0711 l
BVY 93-86 United States Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555
References:
a) mse No. DPR-28 (Docket No. 50-271) b)
L.xr, USNRC to VYNPC, Inspection Report 93-13, dated 07/22/93
Dear Sir:
Subject:
Reply to Notice of Violation - Inspection Report 93-13 This letter is written in response to Reference b), which documented that one of our activities was i
not conducted in full compliance with NRC requirements. The Violation was identified and reported by station personnel in Licensee Event Reports93-006 and 93-009 and in NRC Inspection Report 93-13.
Our response to the Notice of Violation is provided below.
VIOLATION:
" Technical Specification 3/4.2.A., Table 3.2.1 requires, in part, that the core spray high sparger pressure instruments ne calibrated to a setpoint of less than or equal to 5 pounds per square inch differential pressure (psid).
Contrary to the above, on May 27,1993, Vermont Yankee determined that due to improper calibration of the core spray high sparger pressure instruments, both the "A" and "B" instrument setpoints exceeded the Technical Specification limit. This condition existed since November 1979.
This is a Severity 12rel IV Violation (Supplement I)."
RESPONSE
Based on e= root cause analysis, this event occurred as a result of personnel error in applying the required head correction to the differential pressure indicator, but not the alarm point. Since there is no direct correlation between the alarm setpoint and the indication, the l ead correction did not affect the alarm setpoint which remained non-conservative. Failure to apply the head correction to the alarm setpoint resulted ia an actual alarm setpoint greater than the Technical Specification limit. The differential pressure indicator correction was first applied in 1979 in response to General Electric SIL 300.
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'U.S. Nuclear Regulatory Commission VERMONT YANKEE NUCLEAR POWER CORPORATION August 19, 1993 Page 2 I
Our root cause analysis also revealed that the Vermont Yankee Technical Specification may be non-conservative. SIL 300, states that the maximum expected differential pressure across the reactor vessel shroud during a core spray sparger break is expected to be 4 psid The Vermont Yankee Technical Specifications state that the differential pressure setpoint should be i 5 psid.
CORRECTIVE ACTIONS:
=
Immediate:
On May 28,1993, an interim administrative setpoint of.<_4 psid for the Sparger Break Detection sensors was imposed by Vermont Yankee management. In addition, the I&C staff prepared a minor change to the applicable procedure which instructed the I&C Specialist to read the trip point on the Barton differential pressure instrument, thus ensuring that the actual trip point was set at the administrative limit of 4 +/.3 psid. The I&C Specialists performing the work were verbally instructed to adjust the switches to the lower end of the limit, or 3.7 psid. This adjustment resulted in the switches being set such that they would trip prior to the expected maximum dp of 4.0 psid. After a review of the field calibration data, the core spray system was declared operable on May 28,1993.
The verbal communication to set the switches to the lower end of the limit or 3.7 psid was not incorporated into the monthly calibration procedure OP 4347, in a timely manner. Subsequently, during the June and July surveillance tests, one of the switches was found to have drifted above the administrative limit of 4.0 psid without the core spray system being declared inoperative. Concurrent with the July performance of the surveillance procedure, a review conducted by the Resident NRC Inspector and a corporate review of LER 93-06 prompted 1&C management to more closely examine the surveillance test data. On July 16, 1993, the "B" Core Spray System was declared inoperative due to an "as-found" d/p of greater than 4.0 psid. The differential pressure switch was reset to 3.7 psid and the l
system was returned to service. The calibration procedure was formally changed at that time to require these switches to be set to 4 +0/.3 psid.
lamg Term:
=
1.
The I&C Procedure Writer's Guide, AP 0310, will be revised to instruct procedure writers and l
reviewers to include a section that details the setpoint determination and includes any offsetting l
or head corrections as a separate section. This will be completed by September 1993.
I 2.
Procurement requests have been submitted to purchase two new Barton Differential Pressure l
Indicating Switches, with an indicating range of-5 to +5 psid to better suit the application, j
i 3.
Other I&C calibration procedures will be reviewed for similar discrepancies. Reviews that address other Barton instruments have been completed and the remainder of the procedure reviews will be completed by October 1993.
l 4.
The Core Spray Sparger Break Detection System design basis and licensing review of the 5 psid l
Technical Specification setpoint value will be completed by September 1993. If this review indicates that an amendment to the Technical Specifications is necessary, a proposed change will j
i be submitted.
'U.S. Nuclear Regulatory Commission VERMONT YANKEE NUCLEAR POWER CORPORATION August 19,1993 Page 3 5.
Each Vermont Yankee department has been instructed to develop a department specific, self-assessment program to ensure there are mechanisms in place to maintain ongoing cognizance of industry experience developments.
We trust the information provided is adequate; however, should you have any questions or require additional information, please do not hesitate to contact us.
Sincerely, Vermont Yankee Nuclear Power Corporation gnc)
L. kcl't James P. Pelletier Vice President, Engineering
/dm cc:
USNRC Region 1 Administrator USNRC Resident inspector - VYNPS USNRC Project Manager - VYNPS l
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