NRC Generic Letter 1980-66

NRC Generic Letter 1980-066: Transmittal of Supplement No. 1 to IE Bulletin 1980-017, Failure of 76 of 185 Control Rods to Fully Insert During a Scram at a Bwr.

ML031350407
Person / Time
Issue date:	07/18/1980
From:	Sayfrit K NRC Region 4
To:
References
BL-80-017, Suppl 1 GL-80-066, NUDOCS 8009180115
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r REate UNITED STATES PDR:HQ

NUCLEAR REGULATORY COMMISSION LPDR

61 REGION IV 70200TIC

61 RYANPLAZAORIVE,SUITE 1000IC

ARLINGTON, TEXAS 76012 NSIC

July 18, 1980

Docket No. 50-298 Nebraska Public Power District ATTN: J. M. Pilant, Director Licensing & Quality Assurance Post Office Box 499 Columbus, Nebraska 68601 Gentlemen:

Enclosed is IE Supplement No. 1 to Bulletin No. 80-17 which requires action by you with regard to your power reactor facility 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, Karl V. Seyfrit Director N

Enclosures:

1. IE Supplement No.. 1 to Bulletin No. 80-17

2. List of Recently Issued IE Bulletins cc: L. C. Lessor, Superintendent Cooper Nuclear Station Post Office Box 98 Brownville, Nebraska 68321

8009 18 0//5

I

SSINS No.: 6820

Accession No.:

UNITED STATES 8006190027 NUCLEAR REGULATORY COMMISSION

OFFICE OF INSPECTION AND ENFORCEMENT

WASHINGTON, D.C. 20555 IE Bulletin No. 80-17 Supplement No. 1 Date: July 18, 1980 FAILURE OF 76 OF 185 CONTROL RODS TO FULLY INSERT DURING A SCRAM AT A BWR

Description of Circumstances

Please refer to IE Bulletin 80-a7, 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 Bulletin 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") drpin 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

IE Bulletin No. 80-17 Supplement No. 1 Date: July 18, 1980 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 detailed 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 initiate 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 Supplement No. 1 Date: July 18, 1980 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 system or locally installing vacuum breakers close to each such volume should be con- sidered (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.

Licensees of all operating BWRs shall submit the information requested within the specified allowable times. This information is requested under the provis- ions of 10 CYR 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 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 DC 20555.

Approved by GAO, B180225 (R0071); clearance expires 7-31-80. Approval was given under a blanket clearance specifically for identified generic problems.

IE Bulletin No. 80-17 July 18, 1980

RECENTLY ISSUED IE BULLETINS

Bulletin Subj ect Date Issued Issued To No.

80-10 Contamination of 5/6/80 All power reactor Nonradioactive System and facilities with an Resulting Potential for Operating License (OL)

Unmonitored, Uncontrolled or Construction Permit Release of Radioactivity to Environment (CP)

80-11 Masonry Wall Design 5/8/80 All power reactor facilities with an Operating License (OL),

except Trojan and holders of a Construction Permit (CP)

80-12 Decay Heat Removal System 5/9/80 Each PWR with an Operability Operating License (OL)

or Construction Permit (CP)

80-13 Cracking In Core Spray 5/12/80 All BWRs with an Spangers Operating License (OL)

or Construction Permit (CP)

80-14 Degradation of Scram 6/12/80 All BWRs with an Discharge Volume Operating License (OL)

Capability or Constructiou Permit (CP)

80-15 Possible Loss of Emergency 6/18/80 All nuclear facilities Notification System (ENS) holding Operating Licenses with Loss of Offsite Power (OLs)

80-16 Potential Misapplication 6/27/80 All Power Reactor of Rosemount Inc., Models Facilities with an

1151 and 1152 Pressure Operating License (OL)

Transmitters with Either or a Construction Permit

"A" or "D" Output Codes (CP)

80-17 Failure Of 76 of 185 7/3/80 All BWR power reactor Control Rods To Fully facilities holding Insert During A Scram Operating Licenses (OLs)

At A BWR or Construction Permit (CP)

Enclosure