Headquarters Daily Report APRIL 14, 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 APRIL 14, 1997 MR Number: H-97-0039 NRR DAILY REPORT ITEM GENERIC COMMUNICATIONS NRC Information Notice 94-14, Supplement 1, "Failure to Implement Requirements for Biennial Medical Examinations and Notification to the NRC of Changes in Licensed Operator Medical Conditions," dated April 14, 1997. The NRC is issuing this information notice to remind addressees to notify the NRC of changes in a licensed operator's physical or mental condition, as determined by a physician, that cause the operator to fail to meet the medical requirements of Part 55, "Operators' Licenses," of Title 10 of the Code of Federal Regulations (10 CFR Part 55). Technical contacts: Donald J. Florek, RI John L. Pellet, RIV (610) 337-5185 (817) 860-8159 Thomas A. Peebles, RII Stuart A. Richards, NRR (404) 331-5541 (301) 415-1031 Dell R. McNeil, RIII (630) 829-9737 _ REGION I MORNING REPORT PAGE 2 APRIL 14, 1997 Licensee/Facility: Notification: Baltimore Gas & Elec Co. MR Number: 1-97-0027 Calvert Cliffs 2 Date: 04/14/97 Lusby,Maryland NRC INSPECTION IN PROGRESS Dockets: 50-318 PWR/CE Subject: UNPLANNED PERSONNEL EXPOSURE WHILE DIVING IN THE SPENT FUEL POOL Discussion: During a diving operation in the Unit 2 Spent Fuel Pool, on April 3, 1997, to repair components affecting the operation of the Unit 2 fuel handling transfer cart/upender, a diver left the approved diving area, moved to an area that was in closer proximity to stored spent fuel, and received an unplanned exposure when he entered a significantly higher radiation field. The event occurred as a result of lack of continuous visual observation of the diver, a misunderstanding of the limited extent of the approved dive area (an area that was comprehensively surveyed and characterized to support diving operations, i.e., general area dose rates between 50 and 100 millirem per hour), and a lack of understanding of the approved work. While direct visual observation was not maintained, remote monitoring of the divers multiple dosimetry systems and survey probes by the assigned radiation protection technicians indicated that the diver had entered a high radiation field of 9 rem per hour and increasing. Consequently, the diver was warned and prevented from further exposure, and was subsequently removed from the spent fuel pool for exposure evaluation. Preliminary evaluation based on the multiple TLD (thermoluminescent dosimeter) elements that the diver was wearing indicates a whole body exposure of 245 millirem and an extremity exposure (right hand) of 790 millirem, compared to annual regulatory limits of 5000 millirem, total effective dose equivalent (whole body); and 50,000 millirem, maximum shallow dose equivalent for extremities. While significant personnel exposure was adverted in this instance, due to the quick actions of the assigned radiation protection technicians in responding to alarms from the diver's teledosimetry systems, potential for significant personnel exposure existed. Post dive surveys, performed to characterize the area that the diver entered, revealed accessible (within a few feet of where the individual was warned of the increasing radiation field) dose rates in excess of 12,000 rad per hour due to the proximity of stored spent fuel. While no exposure in excess of regulatory limits is apparent, based on preliminary assessment, the individual has been restricted by the licensee from performing further radiological work activities until a final exposure evaluation is completed. Regional Action: The potential health and safety, and regulatory consequences were recognized during an NRC inspection during the week of April 7, 1997. The licensee's radiological control, task planning, pre-job briefing, and personnel exposure evaluation activities are currently being reviewed and examined as part of this inspection. The senior resident and a senior REGION I MORNING REPORT PAGE 3 APRIL 14, 1997 MR Number: 1-97-0027 (cont.) radiation specialist are continuing review and follow-up on this event. Contact: John White (610)337-5114 Ronald L. Nimitz (610)337-5267 _ REGION IV MORNING REPORT PAGE 3 APRIL 14, 1997 Licensee/Facility: Notification: Pacific Gas & Electric Co. MR Number: 4-97-0037 Diablo Canyon 2 Date: 04/11/97 Avila Beach,California Phone Call From Resident Inspector Dockets: 50-323 PWR/W-4-LP Subject: SHUTDOWN FOLLOWING DISCOVERY OF A CRACK IN COLD REHEAT STEAM PIPING Discussion: On April 11, 1997, at approximately 5:42 p.m. (PDT), Diablo Canyon Power Plant, Unit 2, was shutdown and taken to Mode 3 (greater than or equal to 350 degrees Farenheit), following discovery of a circumferential crack in the main turbine exhaust cold reheat piping (steam line from the high pressure turbine to the moisture separator reheater). The crack was observed after piping insulation was removed to investigate a 20 drops per minute leak. The decision to shutdown the unit was made after a partial inspection of the pipe. The cold reheat piping is 62 inches in diameter and 1 inch thick. The design pressure of the piping is 160 psig. The crack was observed to be 11 inches long (6 percent of circumference) and was located in the toe of a weld. A small section of the crack, approximately 1/2 inch in length, was through-wall, and the remaining 10 1/2 inches was near-through-wall. A separate 2 inch indication was found in the pipe and was separated from the 11 inch crack by a 4 inch ligament. The licensee's pipe inspection found that there had been a past modification or weld repair in the area near the leak. Preliminary fracture mechanics analysis indicated that with the existing piping loads, a crack which encompassed 38 percent of the pipe circumference, approximately 6 times larger than the crack found, would be required for the pipe to rupture during operation. Although the cold reheat piping is considered to be a part of the high pressure turbine, and is a nonsafety-related system not subject to ASME/ANSI rules, it was originally designed to meet or exceed the requirements of ANSI B31.1. The piping is under the licensee's erosion/corrosion program. The licensee has reviewed the design of the cold reheat piping and performed additional inspections of the piping without any significant problems being observed. The licensee has determined that the stresses on the system are less than 10 percent of the ANSI B31.1 code allowable. On April 13, 1997, the licensee completed a 1/2 inch thick "weld overlay" repair of the crack. The weld overlay thickness, as well as the supporting stress analysis, were based upon maintaining a ANSI B31.1 design utilizing engineering judgment. The licensee plans to continue to monitor both the weld overlay and the crack during the remainder of the Unit 2 operating cycle. Unit 2 returned to Mode 1 operation on April 13, 1997, at 6:30 p.m. (PDT). REGION IV MORNING REPORT PAGE 4 APRIL 14, 1997 MR Number: 4-97-0037 (cont.) Regional Action: The senior resident inspector monitored the unit shutdown in the control room and subsequent licensee actions taken prior to restart of the unit. Contact: H. Wong (510)975-0296 M. Tschiltz (805)595-2354 _