ML20138M153

Ro:On 850927,employee Observed That Fuel Grapple on Refuel Floor Latched to Spent Fuel Bundle & Trolley Moved,Damaging Mast.Caused by Operator error.Two-man Rule Imposed Until Investigation Complete.Mast Will Be Repaired

ML20138M153
Person / Time
Site:	Pilgrim
Issue date:	10/17/1985
From:	Harrington W BOSTON EDISON CO.
To:	Murley T NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
References
85-188, NUDOCS 8512200276
Download: ML20138M153 (3)

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BOSTON EDISON COMPANY S00 BOvLSTON STREET BOSTON, MASSACMuSETTS D3199 WILLIAM O. MARASNeTON o-October 17, 1985 DECO Ltr. #85-188 Dr. Thomas E. Murley Administrator, Region I U.S. Nuclear Regulatory Commission 631 Park Avenue King of Prussia, PA 19406 License No. DPR-35 '

Docket No. 50-293

Subject:

Refuel Floor Incident of 9/26/85

Dear Dr. Murley:

This letter refers to Boston Edison Company's investigation of the refuel bridge damage of September.26, 1985 which was also independently investigated by Messrs. J. Johnson, L. Briggs, G. Smith, and Dr. McBride of your office as NRC Inspection Report #85-29. The issues were subsequently discussed by Messrs. A. L. Oxson and R. Starostecki in a 10/3/85 telecon, and it was decided that this letter would be submitted to outline the important events and list Boston Edison Company's investigative process and subsequent i corrective measures.  ;

Background

On September 27, 1985, at 0900 hours0.0104 days <br />0.25 hours <br />0.00149 weeks <br />3.4245e-4 months <br />, an employee observed that on the refuel floor (Reactor Building, Elevation 117'), the fuel grapple was t latched to a spent fuel bundle and the trolley had been moved, thus damaging ~the mast. For the last several weeks, the fuel grapple had been used for moving spent fuel as part of the fuel pool clean-up and re-rack projects. Prior to the employee's observation of damage, the fuel grapple had last been secured at 1450 hours0.0168 days <br />0.403 hours <br />0.0024 weeks <br />5.51725e-4 months <br /> -on September 26, 1985. A Failure and Malfunction Report was subsequently filed, and Boston Edison initiated a fuel pool-inventory check and a security investigation. The inventory check: verified that all spent fuel bundles were present.

l Ac_tions Completedi BECo Corporate Security conducted interviews of selected personnel who -

would have been involved or witnessed the event. A copy of their-report will be made available to the Resident Inspector.

- Operations personnel had completed operability testing on-the Emergency Core Cooling Systems and no problems were identified.

9512200276 851017 5 1 7 aoOm Goo g ,

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I BOSTON TDISON COMPANY Dr. Thomas E. Murley U.S.' Nuclear Regulatory Commission October 17, 1985 Page Two

- . A two-man rule was immediately imposed until BECo's security investigation had been completed. Additionally, contractor personnel were excluded from the process buildings (with the exception of fire protection and security personnel). A procedure was subsequently implemented to enforce these requirements. Currently, the two-man rule is still in effect for the refuel floor. Additionally, special combinations / keys have been installed for the refuel floor and are under the control of the Watch Engineer.

- Several " Radiation Area Mey Control" improvements have been implemented including: (a) the number of areas required to be locked has been reduced, (b) the key locker has been relocated to a more secure area, and (c) large key discs have been affixed to the keys to heighten workers' sense of personal cognizance when they are in g possession of one of the keys.

- ~The Medical Department reviewed the psychiatric evaluations (MMPI) of selected personnel in order to assist BECo Corporate Security in focusing their interviewing process.

Operations personnel wrote and implemented a procedure which provided the opportunity to re-enact what was believed to be the "most probable scenario."

The. portions of Procedure 4.3 (" Fuel Handling") which deal with the movement of spent fuel were revised to require upon completion of a fuel movement activity specific verification that:

o Nothing is attached to the grapple, o The mast is secured in the " Full Up" position.

o There is no physical damage, o The ORC switch is in the " Inhibit" position and padlocked.

o The ORC key is returned to the Control Room Watch Engineer.

Information was released to the media indicating details of the incident and Boston Edison's conclusions.

Actions To Be Completed Boston Edison will repair the mast as soon as the "as-found" condition is no. longer required for investigative purposes.

As a long-term corrective action, plans have been initiated to install a closed circuit television system on the refuel floor which will be monitored on our CAS and SAS systems.

Signs will soon be ' installed in _ critical areas throughout the process buildings.to remind people of good key control practices.

E . .

SpSTON EDISON COMPANY Dr. Thomas E. Murley U.S. Nuclear Regulatory Commission October 17, 1985 Page Three Conclusions

. Boston Edison had initially considered three possible causes of the incident in question:

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(1) operator error (e.g. , oversight);

(2) malicious (or non-malicious) mischief by any combination of entrants onto the refuel floor during the time in question; (3) "Act of Sabotage" After extensive interviewing, demonstrating the viability of an operator error scenario, and careful consideration of the circumstances surrounding the event, Boston Edison has concluded that the most probable cause was operator error. It appears that the personnel who last secured the bridge relied solely on the bridge's indicating lights to ascertain position of the mast and the grapple, thereby neglecting to physically observe the position of the grapple in the water. Failure to physically ensure that the grapple was unhooked from the spent fuel bundle prior to moving the trolley was what caused the damage to the mast. As mentioned earlier in this'~1etter, these visual verification requirements have since been added to the procedure and will preclude recurrence of this type of incident.

The second and especially the third of the three possible causes listed above were discounted early on in the investigation, as it was concluded that there was no substantial evidence of intentional malfeasance.

A special investigator for the Plymouth County District Attorney's office, after conducting his own independent review of the circumstances, has reached a similar conclusion.

If you have any further questions regarding this issue, please do not hesitate to contact me.

Very truly yours, William D. Harrington e cc: 'Mr.-Richard W. Starostecki, Director Division of' Reactor Projects U.S.' Nuclear Regulatory Commission Region I - 631 Park Avenue Ming of Prussia, PA 19406 Mr.T.h. Martin, Director Division of Radiation Safety & Safeguards U.S. Nuclear Regulatory Commission Region I - 631 Park Avenue

-King of Prussia, PA 19406 1