Event Notification Report for February 16, 2000

NRC BULLETIN 91-01 RESPONSE (24-HOUR REPORT)

The following text is a portion of a facsimile received from Portsmouth personnel:

"On 02/18/00 at 1600, the Plant Shift Superintendent (PSS) was notified of a loss of one control parameter, geometry, in NCSA-0705_100.A01 for the X-705 decontamination facility. During a boroscope inspection of the 'A' pre-evaporator loop condenser/condenser tubing, a problem with three tubes were observed. Two tubes have sections missing below the tube sheet, and one tube was crimped such that it did not make a seal against the tube sheet. After discovery of the problem, the pre-evaporator condenser was isolated for repair."

"The second control parameter of NCSA-0705_100.A01, volume, was maintained throughout the inspection."

"There was no loss of hazardous/radioactive material or radioactive radiological contamination exposure as a result of this event."

"SAFETY SIGNIFICANCE OF EVENTS: "During a boroscope inspection of the 'A' pre-evaporator loop condenser/condenser tubing, a problem with three of the tubes was observed. Two of the tubes had sections missing below the tube sheet, and one of the tubes was crimped such that it did not make contact with (seal against) the tube sheet. Per discussion with the system engineer, these failures indicate that the integrity of the tubes could no longer be assured. This is a loss of passive barrier 2(PB2) counted upon in NCSA-0705_100.AOI to maintain double contingency. Since there is no indication that the verification of the cooling water flow was lost, any intermixing of the solutions would have resulted in water entering the tube side of the condenser and getting pumped with condensed solution to overhead storage. Since the downstream components from the tube side of the condenser are evaluated for uranium-bearing solutions, the addition of water to the solution would be bounded by the original solution (i.e., the original solution would be diluted by the water). Therefore, the safety significance of the event is low."

"POTENTIAL CRITICALITY PATHWAYS INVOLVED (BRIEF SCENARIO(S) OF HOW CRITICALITY COULD OCCUR): Given the failure of the condenser tubes integrity, if the pressure of the shell side had been lower (water not valved in) the condensed gas (uranium-bearing solution) could have been discharged along with the pathway that the process water normally takes. This stream leads to the storm sewer system, which has not been analyzed for an accumulation of uranium-bearing material. If the material had settled out/been deposited in an unfavorable location in the sewer system, a criticality could have resulted."

"CONTROLLED PARAMETERS (MASS, MODERATION, GEOMETRY, CONCENTRATION, ETC.): The parameters being controlled under this NCSA were geometry and volume. By taking credit for the integrity of the condenser tubes and verifying the flow of the cooling water on the shell side, the resulting condensed uranium-bearing solution is maintained in a safe geometry environment. Loss of condenser tube integrity meant only the pressure differential of the cooling water prevented the uranium-bearing solution from entering a system not designed for handling that material."

"ESTIMATED AMOUNT, ENRICHMENT, FORM OF LICENSED MATERIAL (INCLUDE PROCESS LIMIT AND % WORST): The system is analyzed for up to 100 wt% U235. Since the secondary control for keeping the uranium-bearing solution in a geometrically favorable system was maintained, (the check on the cooling water), no material was actually introduced into the storm sewer system."

"NUCLEAR CRITICALITY SAFETY CONTROL(S) OR CONTROL SYSTEM(S) AND DESCRIPTION OF THE FAILURES OR DEFICIENCIES: Based on the visual inspection of the tube/tube sheet interface, at least three tubes appear to have failed such that intermixing of the solution is possible. This represents a loss of a passive barrier (P82 in the NCSA) credited for meeting the double contingency principle for the operation."

"CORRECTIVE ACTIONS TO RESTORE SAFETY SYSTEM AND WHEN EACH WAS IMPLEMENTED: At 1730, [the] A, B, and C post-evaporator condensers and 'A' pre-evaporator condenser are tagged out of service. Water and steam are isolated from the condensers."

Portsmouth personnel notified the NRC resident inspector and Department of Energy site representative.

* * * UPDATE AT 1335 ON 2/18/2000, BY SPAETH RECEIVED BY WEAVER * * *

This update is being provided to clarify the controlled parameter associated with the NCSA applicable to this event. The NCS parameter being controlled for this event is geometry. Although volume is a parameter identified in the NCSA for this operation, volume is not relevant to this event. Two controls are in place to maintain the geometry parameter, tube integrity and water pressure differential. By taking credit for the integrity of the condenser tubes and verifying the flow of the cooling water on the shell side, the resulting condensed uranium-bearing solution is maintained in a safe geometry environment. Loss of condenser tube integrity meant only the pressure differential of the cooling water prevented the uranium bearing solution from entering a system not designed for handling that material.

The licensee notified the NRC resident inspector. The operations center notified the R3DO(Jorgensen) and NMSS EO (HICKEY).

LICENSEE 24-HOUR REPORT DUE TO EXCEEDENCE OF LICENSED POWER LIMIT

"On February 16, 2000, at 0759 PST Diablo Canyon Power Plant (DCPP) exceeded the Operating License reactor core power of 3411 megawatts by greater than 2 percent. At 0757 PST with Unit 2 at nominal full reactor power a load transient bypass (LTB) signal was initiated diverting main feedwater around the normal feedwater heaters into the steam generators. During the resultant sudden temperature decrease, reactor power peaked at 103.8% and exceeded the nominal full power for a total of six minutes.

"The transient was initiated by utility maintenance personnel during the scheduled performance of instrumentation calibration of circuits associated with the LTB. Technicians performing a calibration inadvertently disturbed an input circuit creating an invalid LTB initiate signal.

"The feedwater temperature was rapidly reduced approximately 45 to 50 degrees F. The Final Safety Analysis Report Update Chapter 15, 'Accident Analyses,' Condition II, 'Faults of Moderate Frequency,' Section 15.2.11, 'Sudden Feedwater Temperature Reduction,' provides bounding analysis for this event. The FSAR Update concludes that for temperature drops of less than 73 degrees F that the reactor will remain in operation and the reactor will not go below the minimum DNBR. FSAR Update Section 15.2.11.1 analysis specifically identifies the inadvertent actuation of the LTB as an initiating event bound by the analysis.)

"The DCPP Unit 2 Operating License DPR-82, Condition 2.C(1) authorizes PG&E to operate Unit 2 at reactor core power levels not in excess of 3411 megawatts thermal (100% rated power). DPR-82, Condition 2.G, 'Reporting,' requires Emergency Notification System reporting within 24 hours and a written followup report within 30 day in accordance with the procedures described in 10 CFR 50.73(b), (c), and (e). This event will be reported as Licensee Event Report (LER) 2-00-001."

************** UPDATE AT 1328 EST ON 03/17/00 FROM RICH LUCKETT TO LEIGH TROCINE **************

The licensee is retracting this event notification because the NRC had rescinded the requirement to make this report and because the licensee had not received it. On 02/24/00, the NRC issued a letter identifying that Operating License DPR-82, as modified by License Amendment No. 120 on 02/03/00, was not properly issued to the correct license. Consequently, the reporting requirement identified was incorrect, and a report was not required.

The licensee notified the NRC resident inspector. The NRC operations officer notified the R4DO (Graves).

TECHNICAL SPECIFICATION REQUIRED SHUTDOWN DUE TO AN UNISOLABLE REACTOR COOLANT PRESSURE BOUNDARY LEAKAGE.

At 1305 EST on 02/16/00 a small leak ("weeping steam") was discovered in the reactor coolant system pressure boundary on a 1.5 inch (ID) post accident sampling system line. The leak is estimated to be 0.03 gpm based on historical trending of the reactor building normal sump. The leak was discovered during a reactor building entry to investigate reactor coolant pump seal indications.

At 1352 EST on 02/16/00 shutdown was commenced. Unit 1 must be in Mode 3 (Hot Standby) by 02/17/00 at 0105 EST and in Mode 5 (Cold Shutdown) by 02/18/00 at 0105 EST per Technical Specification 3.4.13, "Reactor Coolant Operational Leakage."

The post accident sampling line connects to the coolant cold leg piping between the "B" once through steam generator and the suction side of reactor coolant pump "1B2". The leak is coming from the area of a 90 degree elbow where the sampling line passes near the containment floor.

All emergency core cooling systems and the Keowee system are fully operable. The electrical grid is also stable.

The NRC Resident Inspector was notified of this event by the licensee.

UNINTENDED SITE IRRADIATED

While performing high dose rate (HDR) endobronchial brachytherapy, it was discovered that unintended sites in a patient had been irradiated. The licensee uses a Nulceatron Micro Selection HDR #31024, controlled by an IBM G50 computer. It was discovered that after the dwell time was entered into the computer, if the enter key is pushed twice instead of once, the distance that the source moves is increased by 100% without warning the operator that the distance had changed. (If the source is supposed move 4 centimeters and you push the enter key twice that source will move 8 centimeters). A patient received three unintended site radiation treatments to his bronchial tube before the problem was discovered. An NRC Region 3 Inspector was at the facility when this incident occurred.

TEMPORARY FIRE PENETRATION IN THE CABLE SPREADING ROOM WAS FOUND TO BE POTENTAILLY OUTSIDE THE PLANTS DESIGN BASIS.

A condition was discovered which is potentially outside the plants design basis. Engineering review of a temporary fire penetration in the cable spreading room determined that it would not withstand a high energy line break event. This may result in the temperature in the cable spreading room exceeding the design basis temperature for equipment located in the room. The temporary fire penetration has been sealed and is now fully operable.


The NRC Resident Inspector will be notified of this event by the licensee.

NRC BULLETIN 91-01 REPORT

"On 2/16/00 at 1200 Plant Shift Superintendent (PSS) was notified of a loss of one control spacing, in NCSA-0710_006.A01 for the X-710 laboratory facility. During a walk down of proposed revision to the NCSA laboratory personnel discovered that a vertical spacing requirement for storage racks was not being maintained. This was a violation of one control of the double contingency controls established by this NCSA. The other control geometry was maintained through. To regain compliance the containers stored in the affected storage racks were removed and the storage racks were tagged out of service by 1530 hrs.

"SAFETY SIGNIFICANCE OF EVENTS:

"The safety significance of this event is very low. The smallest actual spacing between storage clusters was approximately 11.25 inches. Since each storage bin is 5"x 5", and the tallest arrangement of containers in a bin is approximately 4 inches, the extra inch gap results in adequate spacing between the containers. Also, the enrichment of the containers stored in the bins is limited by PORTS certification to less than 20% versus the 100% enrichment analyzed in the NCSE.

"POTENTIAL CRITICALITY PATHWAYS INVOLVED (BRIEF SCENARIO(S) OF HOW CRITICALITY COULD OCCUR):

"If all the bins were over loaded with containers and the bins were adjacent and all the containers were filled with the analyzed limit of 100% enriched material, a spacing violation with a person carrying a polybottle might cause a criticality.

"CONTROLLED PARAMETERS (MASS, MODERATION, GEOMETRY, CONCENTRATION, ETC.):

"Geometry and Spacing were the controlled parameters. The spacing control was lost when the vertical distance between storage bins was found to be less than 12 inches.

"ESTIMATED AMOUNT, ENRICHMENT, FORM OF LICENSED MATERIAL (INCLUDE PROCESS LIMIT AND % WORST):

"The amount of material is variable depending on whether 2S, 1S or 990 cold traps are considered. The enrichment is analyzed to 100%, although the PORTS' operating certificate limits the cascade to 20%. The form of the material in the containers is UF6. The percent worst case of critical mass is not known, however, at 100% enrichment a single 2S cylinder can contain more than the minimum critical mass. In reality, at 5% enrichment, it would require over 20 25 cylinders to have more than minimum critical mass.

"NUCLEAR CRITICALITY SAFETY CONTROL(S) OR CONTROL SYSTEM(S) AND DESCRIPTION OF THE FAILURES OR DEFICIENCIES:

"Geometry and spacing were controlled. The spacing control was lost because the storage bins were not the correct vertical distance apart.

"CORRECTIVE ACTIONS TO RESTORE SAFETY SYSTEM AND WHEN EACH WAS IMPLEMENTED:

"At 1530 hrs, all controls were regained."

The NRC resident inspector has been informed of this event.

LOSS OF TWO AMERICIUM-241 SOURCES (4 µCi EACH) DUE TO THE CRASH OF AN F-16 NEAR DONALDSONVILLE, GEORGIA

The following text is a portion of a facsimile received from the USAF Radioisotope Committee:

"[...] Date [and] Time of Occurrence or Discovery: 16 Feb 2000/1145 [hours]"

"[...] Organization Possessing Source(s): 347CRS/LGMVS Moody AFB, GA"

"[...] What Happened: [An] F-16 carrying a Low Altitude Navigation Targeting Infrared for Night (LANTIRN) pod crashed (16 Feb 00) in a rural area approximately 10 miles north of Donaldsonville, GA. The Disaster Control Group (DCG) at the scene of the crash confirmed that the F-16 was not [equipped] with a LANTIRN pod. 347CRS/LGMVS, who maintains the pods, notified Lt. Nikel that a pod was on this F-16 and that the DCG had made an error (347CRS notified Lt. Nikel 16 Mar 2000)."

"[...] Radioisotope(s) Involved: Am-241 Activity: 2 sources/4 [µCi] each"

"[...] Sealed Source Model/Serial No.: Model AMM.7 Amersham, Inc."

"[...] Actions Taken to Correct or Abate: The DCG moved all aircraft material from the crash site to Moody AFB, GA. Lt. Nikel will take a team to the DCG storage areas and attempt to search for the pod in the debris."

"[...] Additional Actions Planned and Estimated Time to Complete: An interim or final report will be provided to [the] NRC by 11 April 2000 on disposition of the sources. An investigation will be performed to try and determine why the DCG failed to identify that the F-16 was carrying a LANTIRN pod."

"[...] Additional/Follow-up Information: Sealed Source Device Registry No. NR-136-S-208-S."

(Call the NRC operations officer for contact information.)