ML20236X130
| ML20236X130 | |
| Person / Time | |
|---|---|
| Site: | Vermont Yankee File:NorthStar Vermont Yankee icon.png |
| Issue date: | 07/31/1998 |
| From: | Maret G VERMONT YANKEE NUCLEAR POWER CORP. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| 50-271-98-06, 50-271-98-6, NUDOCS 9808070157 | |
| Download: ML20236X130 (3) | |
Text
- - _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ - _ - _ _ - - _ _ _ _ - _ _ _ _
)
o
?-
VERMONT YANKEE
^
j NUCLEAR POWER CORPORATION
(
185 Old Ferry Road, Brattleboro, VT 05301 7002 i
l (802) 257 5271
)
July 31,1998 BVY 98-116 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk l
Washington, DC 20555
Reference:
(a)
Letter, USNRC to VYNPC, NRC Inspection Report 50-271/98-06 and Notice of Violation, NVY 98-94, dated July 2,1998 l
Subjact:
Vermont Yankee Nuclear Power Corporation License No. DPR-28 (Docket No. 50-271) l Reolv to Notice of Violation - NRC Insoection Report 50-271/98-06 k
l This letter is written in response to Reference (a), which documents the findings of l
an inspection conducted from April 7 to May 21,1998. The inspection identified a I
violation of regulatory requirements. Our response to the Notice of Violation is provided below.
VIOLATION 10CFR50.73(a)(2) requires, in part, that licensees shall submit a Licensee Event Report (LER) within 30 days after the discovery of the event, for any event or condition that alone could have prevented the fulfillment of the safety function of l
structures or systems that are required to control the release of radioactive material to the environment.
Contrary to the above, on March 20,1997, Vermont Yankee identified that the Emergency Operating Procedures (1) directed the operators to flood the containment to the top of active fuel and (2) limited the torus air pressure to a value that would result in the potential to burst the torus rupture disc. This could have resulted in a condition that the containment could not have controlled the release of radioactive h{oj l
material following a design basis accident. However, Vermont Yankee failed to recognize that this was a condition which required them to submit a Licensee Event Report in accordance with 10 CFR 50.73(a)(2) and failed to submit the required report within 30 days.
This is a Severity Level IV violation (Supplement 1).
h 9808070157 400f3t PDR ADOCK 0500CG71 0
PDR I
VERMONT YANKEE NUCLEAR POWER CORPORATION j.
Response
Season for tbe Violation:
Vermont Yankee does not contest this violation. The cause of this event was a cognitive error on the part of plant personnel performing deportability determinations.
The relationship between the plant design bases, the Emergency Operating Procedures (EOPs) and the Severe Accident Management Strategy guidance was misinterpreted with respect to the deportability requirements. Subsequent reviews did not identify the presence of the error.
[
The original reporubility evaluation concluded that entering the containment flooding procedure constituted immediate entry into the Severe Accident Management Strategies, which are designed specifically to cope with postulated conditions beyond the design basis of the plant. The understanding was that the potential for a i
containment breach via actuation of the torus vent rupture disc would only be present if the plant were to be challenged by an event or sequence of events that are outside of the plant design basis. It was incorrectly presumed that the plant conditions needed to precipitate entry into the containment flooding procedure were themselves beyond the plant design basis. It was believed that conditions such as simultaneous l
events or multiple mitigating system failures would be needed to require the use of l
the containment flooding process. It was not promptly recognized that the initiating l
event for this action could originate within design-basis accident response conditions.
When it was recognized that the initiating event was in fact within the design bas!!
of the Vermont Yankee plant (and would lead to containment flooding, thereby introducing the beyond-design-basis torus vent rupture disc vulnerability), it was determined that the condition was reportable pursuant to 10CFR50.73.
Corrective Steos That Have Been Taken and the Results Achieved:
The following Immediate/ Interim actions have been completed:
1.
The Regulatory Compliance Analysts have been appised of the l
relationship between the plant design bases, the EOPs, and the Severe Accident Management Strategies, including the applicable reporting requirements, i
l 2.
Plant management personnel responsible for reviewing and approving l
Potential Reportable Occurrence (PRO) determinations have been apprised of the relationship between the plant design bases, the EOPs, and the Severe Accident Management Strategies, including the applicable reporting requirements.
3.
A procedure change was made to emphasize the appropriate degree of conservatism to be exercised during a deportability determination.
I
VERMONT YANKEE NUCLEAR POWER CORPORATION i
Corrective Actions That Will Be Taken To Prevent Further Violations:
The immediate actions taken are considered adequate to prevent further violations of this type. Additional measures to enhance the deportability evaluation process have been implemented or are being developed. These enhancements include:
o benchmarking of the Vermont Yankee deportability process against those of other facilities, for use in identifying opportunities for further improvement; e
Vermont Yankee participation in the BWROG ad-hoc initiative on deportability; i
e monitoring of NRC rulemaking activities related to 10CFR50.72 and 10CFR50.73; and e
initiation of continuous process improvement efforts to further augment the deportability evaluation process.
l l
These enhancements are ongoing, and we expect to achieve initial results from our j
initiatives by the end of 1998.
l Date When Full Comoliance Was Achieved:
1 J
Full compliance was achieved on May 28,1998 when an LER describing the details of the design vulnerability was submitted to the NRC.
We trust that this information will be satisfactory; however, if you have any questions l
regarding this matter, please contact this office.
I Sincerely, VER O 4
EE NijCliAR POWER CORPORATION A4
%@./aret l
Direch oTOperations l
cc:
USNRC Region 1 Administrator USNRC Resident inspector USNRC Project Manager Vermont Department of Public Service l
l u