NRC Generic Letter 1980-79
| ML031350431 | |
| Person / Time | |
|---|---|
| Issue date: | 08/22/1980 |
| From: | Grier B NRC Region 1 |
| To: | |
| References | |
| BL-80-017, Suppl 3 GL-80-079, NUDOCS 8009120114 | |
| Download: ML031350431 (4) | |
- --- 7l-f C4 UNITED STATES
NUCLEAR REGULATORY COMMISSION
REGION I
631 PARK AVENUE if C -m KING OF PRUSSIA, PEYNSLVN194jf 80
Docket No. 50-271 Vermont Yankee Nuclear Power Corporation ATTN: Mr. Robert L. Smith Licensing Engineer
25 Research Drive Westborough, Massachusetts 01581 Gentlemen:
The enclosed Supplement No. 3 to IE Bulletin No. 80-17, "Failure of 76 of
185 Control Rods to Fully Insert During a Scram at a BWR," is forwarded to you for action. A written response is required.
In order to assist the NRC in evaluating the value/impact of each Bulletin on licensees, it would be helpful if you would provide an estimate of the manpower expended in conduct of the review and preparation of the report(s) required by the Bulletin. Please estimate separately the manpower associated with corrective actions necessary following identification of problems through the Bulletin.
If you desire additional information regarding this matter, please contact this office.
Sincerely, GH.
rier Director Enclosures:
1. Supplement No. 3 to IE Bulletin No. 80-17
2. List of Recently Issued IE Bulletins
CONTACT
- 0. L. Caphton
(215-337-5266)
cc w/encls:
Mr. Warren P. Murphy, Plant Superintendent Mr. W. F. Conway, Vice President and Manager of Operations Mr. J. E. Griffin, President Mr. L. H. Heider, Vice President
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I
8009120 1 14
ENCLOSURE 1 SSINS: 6820
Accession No.:
8006190074 UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF INSPECTION AND ENFORCEMENT
WASHINGTON, D.C. 20555 August 22, 1980
IE Supplement 3 to Bulletin No. 80-17: FAILURE OF CONTROL RODS TO INSERT
NRC staff evaluation of a potential single failure mechanism of the control rod drive control air system has identified the need for licensee actions in addition to those requested by IEB 80-17 and Supplements 1 and 2.
The potential single failure was discussed in IE Information Notice 80-30,
which was issued on August 19, 1980. It involves gradual or partial loss of control air system pressure, which could cause partial opening of scram outlet valves without rod motion. The resultant accumulated seal leakage could conceivably fill the scram discharge volume in a few minutes. Since not all operating BWR's have instrumentation presently installed to continuously indicate water level in the scram discharge volume headers and to provide a control room alarm or scram function, the possibility exists for the scram discharge volume to fill to a level which could prevent reactor scram before automatic protective action or before the operators could be warned.
In view of the possible single failure mechanism described above, the following actions are requested in addition to those specified in IE Bulletin 80-17, Supplements 1 and 2:
1. For those plants in which the scram discharge volume headers are connected to the instrument volume by a 2 inch pipe, within five days of the date of this Bulletin, provide or verify that procedures are in effect to:
a. Require an immediate manual scram on low control rod drive air pressure with a minimum 10 psi margin above the opening pressure of the scram outlet valves.
b. Require an immediate manual scram in the event of:
(1) Multiple rod drift-in alarms, or
(2) A marked change in the number of control rods with high temperature alarms.
Installation of water level instrumentation in the scram discharge volume with level alarm and continuous level indication in the control room, in response to Item B.1 of IEB 80-17 Supplement No. 1, may provide a basis for relaxation of the time for initiating a manual scram.
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IE Bulletin No. 80- 1 August 22, 1980
Supplement No. 3 2. In addition, every BWR licensee is requested within five days of the date of this bulletin to provide and implement procedures which require a functional test using water for the instrument volume level alarm, rod block and scram switches after each scram event, before returning to power. This procedure should remain in effect until modifications in addition to Item B.1 of IEB 80-17 supplement No. 1 are completed to substantially increase reliability of water level indication in the scram discharge volume(s).
Licensees of all operating BWRs shall submit a report summarizing action taken in response to the above items within 10 days of the date of this Bulletin Supplement. Accordingly, you are requested to provide within 10 days as specified above, written statements of the above information signed under oath or affirmation. Reports shall be submitted to the Director of the appropriate NRC Regional Office and a copy forwarded to the Director, Division of Reactor Operations Inspection, NRC. Office of Inspection and Enforcement, Washington, D.C. 20555 Approved by GAO, B180225 (R0072); clearance expires July 31, 1980. (Application for renewal pending before GAO.) Approval was given under a blanket clearance specifically for identified generic problems.
Supplement 3, IE Bulle'in No. 80-17 Enclosure 2 August 22, 1980
RECENTLY ISSUED
IE BULLETINS
Bulletin Subject Date Issued Issued To No.
80-20 Failures of Westinghouse 7/31/80 All holders Type W-2 Spring Return of a power to Neutral Control Switches reactor OL
or CP
Revision 1 Failures of Mercury- 8/15/80 All holders to 80-19 Wetted Matrix Relays in of a power Reactor Protective Systems reactor OL
of Operating Nuclear Power or CP
Plants Designed by Combustion Engineering
80-19 Failures of Mercury- 7/31/80 All holders of Wetted Matrix Relays in a power reactor Reactor Protective Systems OL or CP
of Operating Nuclear Power Plants Designed by Combustion Engineering
80-18 Maintenance of Adequate 7/24/80 All holders of Minimum Flow Thru Centrifuaal a PWR power Charging Pumps Following reactor OL
Secondary Side High Energy and holders Line Rupture of a PWR
Construction Permit nearing licensing Supplement 2 Failures Revealed by 7/22/80 All holders of to 80-17 Testing Subsequent to -a BWR power Failure of Control Rods reactor OL or to Insert During a Scram CP
at a BWR
Supplement 1 Failure of Control Rods 7/18/80 All holders of to 80-17 to Insert During a Scram a BWR power at a BWR reactor OL or CP
80-17 Failure of Control Rods 7/3/80 All holders of to Insert During a Scram .a BWR Dower reactor at a BWR OL or CP
80-16 Potential Misapplication of 6/27/80 All holders of a Rosemount Inc., Models 1151 power reactor and 1152 Pressure Transmitters OL or CP
with Either "A" or "D" Output Codes