ML19330B856
| ML19330B856 | |
| Person / Time | |
|---|---|
| Site: | Vermont Yankee File:NorthStar Vermont Yankee icon.png |
| Issue date: | 07/18/1980 |
| From: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | Rich Smith VERMONT YANKEE NUCLEAR POWER CORP. |
| References | |
| NUDOCS 8008070079 | |
| Download: ML19330B856 (1) | |
Text
W ps* C*:%
g o
' UNITED STATES
[
~,{ '
NUCLEAR REGULATORY COMMISSION L
j REGION I 631 PARK AVENUE
,o',4 KING oF PRUSSIA, PENNSYLVANIA 19406 July 18, 1980 D2cket No. 50-271 Vermont Yankee Nuclear Power Corporation ATTN: Mr. Robert L. Smith Licensing Engineer 25 Research Drive Westborough, Massachusetts 01581 Gentlemen:
The enclosed IE Supplement No. I to Bulletin No. 80-17 which requires action by you with regard to your power reactor facility (ies) with an operating license.
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.
Should you have any questions regarding this Bulletin or the actions required by you, please contact this office.
Sincerely,
% VH. A fdz w B ce H. Grier rector
Enclosures:
1.
IE Supplement No. 1 to Bulletin No. 80-17 2.
List of Recently Issued IE Bulletins CONTACT:
D. L. Caphton (215-337-5266) cc w/encls:
Mr. Warren P. Murphy, Plant Superintendent Ms. J. Abbey, Technical Secretary Mr. J. E. Griffin, President Mr. L. H. Heider, Vice President I
80080700M
ENCLOSURE 1 SSINS No.:
6820 AccessionNo[.:
8006190027 m4 UNITED STATES NUCLEAR REGULATORY COMMISSION
'f 0FFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 Date:
July 18, 1980 IE Bulletin No. 80-17 Supplement No. 1 FAILURE OF 76 0F 185 CONTROL RODS TO FULLY INSERT DURING A SCRAM AT A BWR Description of Circumstances:
Please refer to IE Bulletin 80-17, issued July 3, 1980, for complete details of the initiating event.
Although we are essentially confident that the event was caused by water in the Scram Discharge Volume (SDV) system, we do not yet have a complete explanation as to why the water was present.
The best estimate is that some type of blockage existed in the vent and/or drainage system for the SDV, precluding adequate drainage.
To ensure that the SDV is empty, Browns Ferry (BF-3) has installed instrumentation to continuously monitor the water level in the scram discharge volume.
Such instrumentation is being considered by other plants.
Since issuance of IE Builetin 80-17, additional information has been identified.
Specifically:
a)
At Browns Ferry a discrepancy was found between the "as-built" scram discharge system and the "as-designed" system.
An unused one-inch (1")
instrument line was found uncapped on the four-inch (4") drain header on the west side (the side whose rods scrammed) scram discharge volume vent system of Unit No. 3.
It is believed that this line improved the venting, and therefore the drain time for that system.
b)
It has been determined that the vent systems on some scram discharge volumes interconnect with vent headers that are also common with and are connected to other systems.
The interconnected " vent" systems may contain water drained or being drained from those other systems.
This water could potentially affect performance of the SDV.
Also, both the vent and drain systems for the scram discharge system may contain long lengths of relatively small bore piping.
Designs specify a very gradual slope, such that small errors in the "as-installed" piping could result in degraded performance (for example, due to loop seals).
c)
Concerns have been expressed within the NRC Staff regarding potential delays that may occur before start of injection of boron into the BWR system from the Standby Liquid Control System (SLCS) when this manual operator action is required.
The potential delays could be caused by
r IE Bulletin No. 80-17 July 18, 1980 Supplement No. 1 Page 2 of 3 unavailability of the SLCS key which is required to initiate this system, and/or administrative delays which require supervisory approval before the SLCS can be manually initiated by the control room licensed operator.
In view of the above items, the following actions in addition to those specified in IE Bulletin 80-17 are to be taken by BWR licensees.
A.
Actions to be Taken by BWR Licensees Upon Receipt and to be Reported Within 20 Days of the Date of This Letter:
1)
Provide to the NRC Regional Office an analysis of the adequacy of the "as-built" SDV system and associated vent and drain systems, including any identified design deficiencies.
Include copies of verified "as-built" isometric drawings of the SDV and oetailed descriptions of the remainder of the system, verified to be correct, as part of this analysis.
2)
Revise and implement Operating Procedures as necessary to provide clear guidance to the licensed operator in the control room regarding when he should init' ate the SLCS without obtaining prior supervisory approval.
Provide a description of the implemented procedural requirements.
3)
Assure that procedures exist and are implemented for specifying remedial action to be taken if water is found in the SDV system at times when it should be free of water.
Provide a description of the implemented procedural requirements.
4)
Revise and implement administrative procedures as necessary to ensure that the SLCS key shall be readily available to the licensed operator in the control room.
Provide a description of the implemented pro-cedural requirements.
5)
Continue daily monitoring of water levels in all scram discharge volumes until continuous monitoring system (s) (discussed in B.1 below) is (are) installed and operational (this requirement supersedes the requirements of Item 5 of IE Bulletin 80-17 which required daily surveillance for only 6 days).
B.
Actions to be Taken by BWR Licensees and Completed by September 1, 1980:
1)
Install a system to continuously monitor water levels in all scram discharge volumes.
Continuous recording and alarm features must be included in the design.
Consideration should be given to use of diverse level sensors in this (these) system (s).
The design installed should represent the design with the highest level of reliability compatible with completion of installation by September 1, 1980.
Provide a written description of the system design to the NRC Regional Office.
IE Bulletin No. 80-17 July 18, 1980 Supplement No. 1 Page 3 of 3 If installation by September 1,1980 is not possible, by August 15, 1980, submit to the NRC Regional Office:
1)
Documentation in detail why the installation cannot be completed by 9/1/80.
2)
A commitment to a firm schedule for installation.
3)
A commitment to equipment changes and/or surveillance requirements in addition to those now in effect that will provide adequate assurance of SDV operability in the interim until installation is completed.
2)
Perform a study of potential designs for improving the venting system for the scram discharge volumes and submit a description to NRC by September 1, 1980.
Improvements such as providing a redundant, independent vent for each significant volume in the systerr. or locally installing vacuum breakers close to each such volume should be considered (some plants already include a design which vents locally to atmosphere).
Include an estimate of the time that would be required to accomplish these modifications in your report to be submitted to the NRC Regional Office.
We have been told that meetings have already been scheduled by GE to discuss their proposals in this area with licensees.
Additional requirements are under consideration and will be the subject of further communication from NRC.
Licent;ees of all operating BWRs shall submit the information requested within the specified allowable times.
This information is requested under the provisions of 10 CFR 50.54 (f).
Accordingly, you are requested to provide within the time periods specified above, written statements of the above information signed under oath or affirmation.
Reports shall be submitted to tha 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 DC 20555.
Approved by GAO, B180225 (R0071); clearance expires 7-31-80.
Approval was given under a blanket clearance specifically for identified generic problems.
a IE Supplement No. 1 to Bulletin No. 80-17 July 18, 1980 RECENTLY ISSUED IE 8ULLETINS Bulletin Subject Date Issued Issued To No.
80-17 Failure of 76 of 185 7/3/80 All holders of a BWR Control Rods to Fully OL or CP Insert During a Scram at a BWR 80-16 Potential Misapplication of 6/27/80 All holders of a power Rosemount Inc. Models 1151 reactor OL or CP and 1152 Pressure Trans-mitters with Either "A" or "D" Output Codes 80-15 Possible Loss Of Hotline 6/18/80 All holders of a power With Loss Of Off-Site Power reactor OL and fuel cycle licensees connected to Emergency Notification System 80-14 Degradation of Scram 6/12/80 All holders of a BWR OL Discharge Volume Capability 80-13 Cracking In Core Spray 5/12/80 All holders of a BWR OL Spargers 80-12 Decay Heat Removal System 5/9/80 All holders of a PWR OL Operability 80-11 Masonry Wall Design 5/8/80 All holders of a power reactor OL, except Trojan 80-10 Contamination of 5/6/80 All holders of a power Nonradioactive System and reactor OL or CP Resulting Potential for Unmonitored, Uncontrolled Ra' ease to Environment 80-09 Hydramotor Actuator 4/17/80 All holders of a power Deficiencies reactor OL or CP 80-08 Examination of Containment 4/7/80 All holders of a power Liner Penetration Welds reactor with a CP and/or OL no later than April 7, 1980 l
-