NRC Generic Letter 1980-54

NRC Generic Letter 1980-054: Transmittal of IE Bulletin 1980-014, Degradation of BWR Scram Discharge Volume Capability.

ML031350403
Person / Time
Issue date:	06/12/1980
From:	Engelken R NRC Region 4
To:	Jacobson G
References
BL-80-014 GL-80-054, NUDOCS 8007140418
Download: ML031350403 (4)

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-t I UNITED STATES

NUCLEAR REGULATORY COMMISSION

REGION V

1990 N. CALIFORNIA BOULEVARD

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SUITE 202. WALNUT CREEK PLAZA

WALNUT CREEK, CALIFORNIA 94596 A- I

June 12, 1980

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G L7 Docket Nos. 50-522, 50-523 Puget Sound Power & Light Company Puget Power Building Bellevue, Washington 98009 Attention: Mr. G. W. Jacobsen Project Manager - Nuclear Gentlemen:

The enclosed IE Bulletin No. 80-14 is forwarded to you for information.

No written response is required. If you desire additional information regarding this matter, please contact this office.

Sincerely, R. H. Engelken Director Enclosures:

1. IE Bulletin No. 80-14

2. List of Recently Issued IE Bulletins

800714 019W

SSINS No.: 6820

Accession No.:

UNITED STATES 8005050056 NUCLEAR REGULATORY COMMISSION

OFFICE OF INSPECTION AND ENFORCEMENT

WASHINGTON, D.C. 20555 June 12, 1980

IE Bulletin No. 80-14 DEGRADATION OF BWR SCRAM DISCHARGE VOLUME CAPABILITY

During our review of BWR operating experience, two events have raised concern on operations related to the control rod drive system scram discharge volume (SDV).

Description of Circumstances

At Hatch Unit 1, on June 13, 1979, while performing surveillance to func- tionally test SDV high level switches, two switches (C11-NO13A, B) were found to be inoperable. Redundant switches (C11-N013 C, D) were operable. The reactor was in the refuel mode and these switches had been modified prior to this occurrence. Inspection of the inoperable level switches revealed that the float rod was bent and binding against the side of the float chamber on both switches. The licensee believes that the float rods were bent during or prior to initial installation and that metal particles from the modification caused binding of the float. (LER 79-038)

Brunswick Unit 1 reported that slow closure of the SDV drain valve during a reactor scram on October 19, 1979 apparently caused a water hammer event which damaged several pipe supports on the SDV drain line. Drain valve closure time was approximately five minutes due to a faulty solenoid controlling air supply to the valve. The damaged pipe supports were repaired but repair parts for the faulty solenoid were not available. To prevent possible damage from a scram, the unit started up with the SDV vent and drain valves closed except for periodic draining. During this mode of operation the reactor scrammed from high level in the SDV, without prior actuation of either the high level alarm or rod block switch. Subsequent inspection revealed that the float ball on the rod block switch was crushed and the float ball stem on the high level alarm switch was bent such that the switches would not operate. The water hammer event discussed above was the reported cause of failure of these two switch assemblies. (LER 79-74)

As a result of these events and related anticipated transients without scram (ATWS) studies, concern arises that the SDV function may be degraded by the undetected presence of fluid in the SDV. The second event is significant in that it indicates the potential for a common cause failure (faulty solenoid)

to result in operation of the SDV in a manner which could defeat both the level switch function and the SDV draining function. The ATWS generic studies (NUREG 0460) have led the staff to propose, among other requirements, improve- ments in the SD' designs to reduce susceptibtifty to comion cause failures.

By separate correspondence, the staff will provide example Technical Specifica- tions related to the action items discussed below.

IE Bulletin No. 80-14 June 12, 1980 A. GE BWR's With an Operating License The following actions are to be taken by licensees of GE designed BWR

facilities with an operating license:

1. Review plant records for instances of degradation of any SDV level switch which was or may have been caused by a damaged or bent float assembly.

Identify the cause and corrective action for each instance.

2. Review plant records for instances of degradation of SDV vent and drain valve operability. Provide the closure times required and typically observed for these valves and the basis for the required closing times.

Identify the cause and corrective action for each instance of degradation.

3. By procedures, require that the SDV vent and drain valves be normally operable, open and periodically tested. If these valves are not operable or are closed for more than 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> in any 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> period during operation, the reason shall be logged and the NRC notified within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> (Prompt Notification).

4. Review instances in which water hammer or damage which may have been caused by water hammer has occurred in SDV related piping. Identify the cause and corrective action for each instance.

5. Review surveillance procedures to ensure that degradation of any SDV

level switch due to a damaged float or other cause would be detected and that inoperability from any cause would be reported to the NRC.

6. If no functional test or inspection which would detect degradation of each SDV level switch has been performed during the past 3 months, make provisions to perform an inspection and functional test of all SDV level switch assemblies at the next reactor shutdown of greater than 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> duration.

B. Reporting Requirements The action taken in response to the items in Part A shall be completed and a written report on the results submitted to the NRC within 45 days from the date of this Bulletin.

This report should be submitted to the Director of the appropriate NRC Regional Office and a copy should be forwarded to the NRC Office of Inspection and Enforcement, Division of Reactor Operations Inspection, Washington, D.C.

20555.

Approved by GAO, B180225 (R0072); clearance expires 7-31-80. Approval was given under a blanket clearance specifically for identified generic problems.

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IE Bulletin No. 80-14 Enclosure June 12, 1980

RECENTLY ISSUED

IE BULLETINS

Bulletin Subject Date Issued Issued To No.

80-13 Cracking In Core Spray 5/12/80 All BWR's with an Spargers OL

80-12 Decay Heat Removal System 5/9/80 Each PWR with an OL

Operability

80-11 Masonry Wall Design 5/8/80 All power reactor facilities with an OL, except Trojan

80-10 Contamination of 5/6/80 All power reactor Nonradioactive System and facilities with an Resulting Potential for OL or CP

Unmonitored, Uncontrolled Release to Environment

80-09 Hydramotor Actuator 4/17/80 All power reactor Deficiencies operating facilities and holders of power reactor construction permits

80-08 Examination of Containment 4/7/80 All power reactors with Liner Penetration Welds a CP and/or OL no later than April 7, 1980

80-07 BWR Jet Pump Assembly 4/4/80 All GE BWR-3 and Failure BWR-4 facilities with an OL

80-06 Engineered Safety Feature 3/13/80 All power reactor (ESF) Reset Controls facilities with an OL

80-05 Vacuum Condition Resulting 3/10/80 All PWR power reactor In Damage To Chemical Volume facilities holding Control System (CVCS) Holdup OLs and to those with Tanks a CP

79-OiB Environmental Qualification 2/29/80 All power reactor of Class IE Equipment facilities with an OL

80-04 Analysis of a PWR Main 2/8/80 All PWR reactor facilities Steam Line Break With holding OLs and to those Continued Feedwater nearing licensing Addition