ML20210A585

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Discusses Event Re Loss of ECCS Suction Header Support Bolts at Facility.Final Evaluation Will Be Performed After Technical Review Examines Util Test Rept.Related Info Encl
ML20210A585
Person / Time
Site: Quad Cities, 05000000
Issue date: 08/29/1972
From: Riesland J
US ATOMIC ENERGY COMMISSION (AEC)
To: Skovholt D
US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20209J032 List:
References
FOIA-87-40 NUDOCS 8705050120
Download: ML20210A585 (5)
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August 29, 1972 NOTE TO D. J. SKOVHOLT The loss of the ECCS suction header support bolts on Quad-Citics Unit 2 was reported by telex on May 29, 1972. We received our copy on ::ay 30. Taiu was followed by tne IL-day report from CECO dated June 7, 1972. received on June 13, 1972.

Bf the ti=u we received the report, RO had taaen the following actions.

1. Distributed a blue letter (D. Ziemann was not on tue distribution list).
2. Investigated the problam, with a consultant (Ric.iard A.

Lofy), and reviewed CECO's proposed corrective actions including tests.

3. Evaluated tue incident and directed Ceco. by letter dated June 22, l>72. to perform additional inspectionc on Quad-Citics and Dresden Units and report resulta to RO within 10 daya. We have not received CECO's response.

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4. ;4de a prescutation of the incident, RO's evaluation and recommendations, and corrective actions to t;.c ACRS during tae Junc Committee meetings.
5. Aavised us that CECO would submit a report of tneir test results to the regulatory staff by about August 1, 1972. We have not yet received the report. In response to our telepnone inquiry on about August 15, CECO advised us that GE was still working on the report.

Based on the above and CECO's report of corrective measures, we consider no additional action is necessary on our part (without resulting in duplicating the RO efforts) until the test report is submitted. At that time, a technical assistance raquest will be submitted to Technical deview witu pertinent information for their evaluation and recommendations.

8705050120 870428 PDR FOIA Tl .O MAS 87-40 PDR

D. J. SKOVHOLT August 29, 1972 To date Technical Review has not participated in the evaluation of this event. RO has* reviewed information submitted by the licensee, tneir consultant's report, inspected the corrective measures , and made an evaluation. We (Operating Reactors) have reviewed the licensee's report and the RO information. We inspectea the corrective measures at the site on June 15, 1972, two days after receiving the licensee's report and one week af ter RO's blue sheet was issued. Tne corrective measures were acceptable to us as a significant improve-ment over the original design and installation, knowing enat Dresden 2 anu 3 have tue came design as Quad-Cities original design and nave experienced no problems. Tecnnical Review will be asked to review all pertinent information unen ene test results are submitted by the licensee. Waen Technical Review's response is received, we will prepare a final evaluation.

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Date: June 22, 1972 Directorate of Regulatory Operations Bulletin 72-1 FAILED HANGERS FOR EMERGENCY CORE COOLING SYSTEM SUCTION HEADER We re'cently received,information from the Commonwealth Edison Company concerning a problem found during startup testing of the Quad-Cities 2 boiling water reactor which may relate to the design and long term performance capability of the torus and the emergency core cooling suction header at your facility. The information is as follows:

s. Description of Circumstances During startup testing the licensee found that four of the pipe hangers which support the 24-inch diameter torus suction header had failed. The 24-inch suction header serves as the main source of water for the emergency core cooling systems. Water is supplied to the header from the torus through four 20-inch diameter pipes spaced 90 deErees apart. The header is supported by three equally spaced sets of vertical and horizontal hangers which are attached to support plates welded to the torus and which are located between each of the four 20-inch pipes which join the suction header to the torus. A total of 12 hangers support the 24-inch suction header.

The reactor was promptly shut down for investigation and repair following the discovery of the failed hangers.

Three of the four failed hangers were located within a 90 degree section of the header and resulted in a maximum sag in the header pipe of approximately six inches within that section. Four 3/4-inch diameter bolts (threaded their entire length), which secured pairs of shackles to the support plates welded to the torus and to the >

24-inch diameter pipe, were found to have failed in double shear.

The cause of the bolt failures has not as yet been determined; however, it is known that the suction header experienced vibration as a result of operational testing of the emergency core cooling system. In addition, the bolt holes, which were formed by flame cutting and punching, were found to be irregularly shaped and poorly aligned.

Chicago Bridge and Iron Company, the contractor for the torus and suction header design and installation, has provided a revised design requiring use of 1-inch diameter high strength bolts with smooth unthreaded bearing surface, and appropriately increased the size of the shackles. The change is being implemented for all the hangers.

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6 Commonwealth Edison Company and General Electric Company plan to conduct additional investigation to determine the effect on the suction header and torus of routine plant operations and testing of the emergency core cooling systems.

We have also 'been informed that the Northern States Power Company's Monticello reactor found one bent suction header hanger bolt and is also currently replacing the hanger bolts with 1-inch diameter bolts.

b. Action Requested of the Licensee It is requested that you conduct the following inspections for each of your facilities and provide this office with the results of your inspection.
1. An inspection of the hangers, shackles and support plates for the torus suction header to assure that all components are in accordance with design, are in proper position, and do not indicate damage.
2. Inspect each bolt used to attach the shackle and support plate of each hanger (1) for deformation, (2) to establish that bolts are of the specified design, (3) to establish that specified locking devices are installed and (4) that the bolt shank supporting the header weight from the support and shackle is not threaded in the bearing area.

If the results of your inspection indicate the existence of conditions similar to those described above, or if any problems have previously been experienced with failed hangers or bent hanger bolts at your facility, please include in your response a description of the problem and the corrective action taken or planned, if any, and the date of scheduled completion of any planned corrective action. This information should be provided to this office, in writing, within ten days of your receipt of this letter.

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