Headquarters Daily Report SEPTEMBER 24, 1997 *************************************************************************** REPORT NEGATIVE NO INPUT ATTACHED INPUT RECEIVED RECEIVED HEADQUARTERS û REGION I û REGION II û REGION III û REGION IV û PRIORITY ATTENTION REQUIRED MORNING REPORT - HEADQUARTERS SEP. 24, 1997 MR Number: H-97-0117 NRR DAILY REPORT ITEM SIGNIFICANT EVENTS Subject: Calvert Cliffs, Unit 2, Inadequacy of Controls for Diver in Spent Fuel Storage Pool - Classified as a Significant Event The NRR/AEOD Events Assessment Panel meeting on September 16, 1997, classified the inadequacies in licensee control of work in a spent fuel storage pool at Calvert Cliffs, Unit 2, as a Significant Event. Classification was based on the numerous deficiencies in the preplanning and controls implemented to support maintenance activities. Information Notice 97-68, "Loss of Control of Diver in a Spent Fuel Storage Pool," was issued on September 3, 1997. Calvert Cliffs, Unit 2, was in Mode 6 with reactor defueling on hold because of a malfunction of the Unit 2 fuel transfer system. On April 3, 1997, the fourth in a series of diving activities to effect repairs to the fuel transfer system was initiated in the spent fuel pool. As with previous dives which had been made in the refueling cavity normal diving controls were specified by a licensee-approved procedure and a job-specific radiation work permit. The diver entered the spent fuel pool at about 9:00 a.m. to commence work on an upender limit switch at the south end of the fuel transfer area, the only surveyed and authorized work area. Following completion of one part of the work, the diver requested some materials. While waiting for the materials, the diver requested permission to inspect a kink in the upender cable, located in another area of the spent fuel storage pool. A technician approved the request, thinking that the kink was in the approved work area. The diver proceeded to go to the other section of the spent fuel storage pool to inspect the cable. Several communication breakdowns, compounded by several failures in the licensee's control programs, resulted in this entry into an unauthorized area being neither prevented nor detected. Near the north end of the transfer system, the diver stopped to survey a pipe on the west wall of the pool that he did not recognize. During the survey, the monitors on the diver's right and left wrists alarmed. The Radiation Protection (RP) technician instructed the diver to retreat to a lower dose area. The RP technician was not aware that the diver had actually encountered the radiation field from recently off-loaded spent fuel located in the racks on the east side of the transfer area. Without verifying the diver's position, the RP technician instructed the diver to survey the area to locate the source of the unexpected radiation. When the survey meter readout increased to 30 mSv/hr (3 rem/hr), the dive was suspended. Only after the diver surfaced, did the RP personnel realize that the diver had actually been in the north end of the pool. The subsequent assessment of the event revealed that the diver had been several meters outside the surveyed area of the pool and came within a few feet of radiation dose rates ranging from 120 to 200 Gy/hr (12,000 to 20,000 rad/hr). An NRC review of this event identified multiple failures of the licensee controls, including: the scope of work was not clearly understood by all HEADQUARTERS MORNING REPORT PAGE 2 SEP. 24, 1997 MR Number: H-97-0117 (cont.) parties involved prior to start of work; the diver was given inadequate instructions about the location and magnitude of the radiation sources accessible to him; and positive control over the diver in the pool was inadequate. In addition, the licensee failed to adequately evaluate the diver's exposure status before authorizing additional work in the RCA. The licensee allowed the diver to re-enter the RCA prior to dosimetry processing based on a preliminary assessment of the teledosimetry readings, which were inadequate to determine whether he had received a dose in excess of the limits to his extremities. The licensee subsequently calculated a dose of 2.7 mSv (270 mrem) to the highest exposed portion of the diver's whole body and a maximum dose to the extremities of 8.85 mSv (885 mrem). Although the radiation doses received by the diver did not exceed the dose limits given in 10 CFR Part 20, the breakdowns noted above resulted in the diver being able to gain access to a very high radiation area contrary to the requirements of 10 CFR 20.1602. The combination of an extremely intense radiation source and the very steep dose gradients that can be encountered as a diver moves through his shielding (water), make diving in areas where irradiated fuel can be accessed a uniquely hazardous operation. Had the circumstances of this event been only slightly altered, the diver could have been exposed to much higher dose rates. Even with continuous teledosimetry monitoring, it is possible for a diver to inadvertently enter a radiation field and receive a serious radiation dose, in a matter of seconds. Establishing and maintaining proper effective controls is critical to worker safety. Contact: Jerry Carter, NRR/DRPM/PECB (301) 415-1153 _ REGION II MORNING REPORT PAGE 2 SEPTEMBER 24, 1997 Licensee/Facility: Notification: Tennessee Valley Authority MR Number: 2-97-0075 Watts Bar 1 Date: 09/24/97 Spring City,Tennessee Dockets: 50-390 PWR/W-4-LP Subject: UNPLANNED EXPOSURE WHILE RETRIEVING DEBRIS Discussion: On September 21, 1997, with the reactor defueled, a craftsman noted four small foreign objects laying on the reactor vessel flange. The craftsman placed the material in a plastic bag and subsequently removed it from the reactor vessel cavity area without conducting appropriate radiation surveys. One piece of foreign material later showed a contact reading of about 56R/hr. TVA's preliminary calculations and isotopic identification of the material estimated an individual extremity exposure of approximately 25 percent of the 10CFR Part 20 regulatory limits. The objects appear to be parts of an unraveled stainless steel gasket. TVA is continuing with additional radiological analysis and root cause determination. Following flood up of the reactor vessel cavity, the licensee performed underwater camera examination of the reactor vessel and found additional foreign material located on top of the lower core support plate. The foreign material also appears to be small pieces of stainless steel gasket. TVA has assembled an investigation team to determine the source of the foreign material, initiate debris removal, and assess effects on subsequent reload of the core. Regional Action: A Region II Senior Radiation Specialist has been sent to the site to review the licensee's radiological assessments and follow licensee's corrective actions. Resident inspectors are continuing to follow licensee's determination of foreign material intrusion and corrective actions. Contact: Mark S. Lesser (404)562-4560 _