NRC Generic Letter 1980-68

NRC Generic Letter 1980-068: Transmittal of Supplement No. 2 to IE Bulletin No. 80-017, Failures Revealed by Testing Subsequent to Failure of Control Rods to Insert During a Scram at a Bwr.

ML031350410
Person / Time
Issue date:	07/22/1980
From:	Seyfrit K NRC Region 4
To:
References
BL-80-017, Suppl 2 GL-80-068, NUDOCS 8009020534
Download: ML031350410 (4)

st REG&, UNITED STATES

0 aNUCLEAR REGULATORY COMMISSION

REGION IV "

4t tu ,\1o611 RYAN PLAZADRIVE, SUITE 1000

ARLINGTON, TEXAS 76012 July 22, 1980

In Reply Refer To:

RIV

Docket Nos. 50-458/IE Bulletin No. 80-17, Supplement No. 2

50-459/IE Bulletin No. 80-17, Supplement No. 2 Gulf States Utilities Attn: Dr. E. Linn Draper, Jr.

Vice President - Technology Post Office Box 2951 Beaumont, Texas 77704 Gentlemen:

forwarded to you The enclosed Supplement No. 2 to IE Bulletin No. 80-17 is desire additional for information. No written response is required.. If you information regarding this matter, please contact this office.

Sincerely, Karl V. rit Director Enclosures:

1. Supplement No. 2 to IE Bulletin No. 80-17

2. List of Recently Issued IE Bulletins

8009020o54

• I

SSINS No.: 6820

Accession No.:

UNITED STATES 8006190032 NUCLEAR REGULATORY COMMISSION

OFFICE OF INSPECTION AND ENFORCEMENT

WASHINGTON, D.C. 20555 IE Bulletin No. 80-17 Supplement No. 2 Date: July 22, 1980 FAILURES REVEALED BY TESTING SUBSEQUENT TO FAILURE OF CONTROL RODS TO INSERT

DURING A SCRAM AT A BWR

Description of Circumstances

At about 3:35 a.m. on July 19, 1980, a manual scram test was initiated at Dresden Unit No. 3. This test was initiated in accordance with the require- ments of IE Bulletin No. 80-17. The scram itself was accomplished (i.e.,

control rods inserted). Following the scram, the Scram Discharge Volume (SDV)

was monitored by UT in accordance with Item #3 of IE Bulletin No. 80-17. The UT check followed the normal draining of the SDV at a time when personnel conducting the test believed the SDV to be empty. However, the UT check revealed the scram discharge west header bank to be 80% filled with water (i.e., apparently the drain was not successful).

Upon investigation, it appeared that the SDV vent system did not function due to a stuck ball check valve (i.e., a ball check valve functioning as a vacuum breaker). This ball check valve is installed in a tee connection downstream of the vent valve in a one-inch vent header which terminates in the reactor building equipment drain tank (REEDT). The ball check valve provides a vent path to the reactor building atmosphere in the event the vent header does not.

The vent header itself provides a path to other interconnections and extends into the RBEDT under the surface of water normally contained there.

Additional information has also resulted from scram testing at other BWRs as follows:

1. At Duane Arnold, the Scram Discharge Instrument Volume (SDIV) drain valve was found installed so that pressure in the SDIV tended to unseat the drain valve disk. This resulted in leakage out of the SDIV during the scram. This was corrected by reversing and reinstalling the valve. The scram tests were performed on July 12 and 13 and the drain valve was corrected before return to power operations on July 17, 1980.

2. At the Millstone Unit 1, the scram tests were performed successfully on July 11 through 14. The function of the 10-second delay on scram reset (per Item #2.(j) of IE Bulletin No. 80-17) was tested separately from the scram tests. Review of the separate test results by plant personnel established that the scram reset delay feature was not functioning in the scram circuits due to a wiring error on the circuit boards. This was corrected.

IE Bulletin No. 80-17 Supplement No. 2 Date: July 22, 1980 3. At Browns Ferry Unit No. 1, a test scram involving two rods was performed on July 19, 1980. The test showed normal response of level switches in the SDIV. When proceeding to drain the SDIV, however, the SDV did not empty as required and expected. A vacuum in the SDV apparently existed which kept the system from draining. Subsequently, the vacuum was cleared by operator actions and the volume drained properly. Tests are continuing toward determination of the cause and to measure the vacuum.

4. At Nine Mile Point Unit No. 1, one rod failed to scram during the manual scram test on July 14, 1980. This was due to a failure of the scram pilot valve for that rod.

In view of the above-described events,.. the. following actions in addition to.

those specified in IE Bulletin No. 80-17, including Supplement No. 1, are to be taken by BWR licensees.

1. Each BWR licensee with a SDV vent system that depends on any component other than the vent valve alone for proper venting must provide an alter- nate vent path continuously open to building atmosphere on the side of the vent valve piping away from the SDV. This alternate vent path must be positive in its function at all times (i.e., a vent must be effective regardless of component operability other than the vent valve).

Plants have made corrections by providing a vent through a standpipe open to building atmosphere. This was done at Browns Ferry Unit No. 3 and is being done at Dresden Units 2 and 3. It is noted that due consideration to radiological aspects should be included.

An alternate vent path must be provided within 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> following the telephone notification on July 19, 1980 in order to continue or commence operations.

2. Report in writing within 5 days of the date of this Bulletin Supplement the confirmation of your action in response to the above. Reports shall be submitted to the Director of the appropriate NRC Regional Office and a copy shall be forwarded to the NRC Office of Inspection and Enforcement, Division of Reactor Operations Inspection, Washington, D.C. 20555.

More information on the details of the Dresden and Browns Ferry events and modifications can be obtained by contacting the Dresden and/or Browns Ferry operating supervision. In addition, we understand that a General Electric Company task force is available for consultation at (408)925-3188.

For all boiling water power reactor facilities with a construction permit, this Bulletin is for information only and no written response is required.

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

' .

IE Bulletin No. 80-17 Supplement No. 2 July 22, 1980

RECENTLY ISSUED IE BULLETINS

Bulletin Subj ect Date Issued Issued To No.

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 Spargers 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 Construction 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)

Sup. 1 Failure of Control Rods 7/18/80 All BWR power reactor to 80-17 to Insert During a Scram facilities holding Operating at a BWR Licenses (OLs) or Con- struction Permits (CPs)

Enclosure