I. PURPOSE AND SCOPE

The environmental qualification (EQ) rule (10CFR50.49) was originally addressed under project 00912A. In addition to general EQ requirements for installed electrical equipment, the rule includes replacement-equipment requirements in paragraph L. These additional requirements impact Rosemount transmitters. Rosemount model 1152 transmitters (reactor plant pressure, flow, and level instrumentation) are being replaced before the end of their ten year qualified life. The upgrades are being done at this time due to the commitment to meet the requirements of the rule, the approaching end of qualified life, and the availability of a qualified replacement, Rosemount model 1153B transmitters. Rosemount model 1153B instruments are qualified to Category I (NUREG 0588) criteria, as required by 10CFR50.49(L). Upon initiation of this project, approximately 70 of the older Rosemount model 1152 transmitters were in use in Unit 1 and 65 in Unit 2. Unit 1 replacements have been completed; there are 22 model 1152 transmitters scheduled to be replaced in Unit 2. This project will be successful if all Rosemount transmitters are replaced before their design end of life.

II. EVALUATION

Schedule Index: 22 - The installed Rosemount transmitters are critical pressure, level, and flow instrumentation components in safety-related systems. Replacing the Rosemount transmitters with a more reliable model will reduce the probability that automatic functions would fail to actuate during an accident scenario, especially in the harsh environments possible during a postulated accident. Since emergency operating procedures direct the operators to start equipment manually when the automatic signal has failed and since critical automatic function signals are redundant by design, the impact of this type of equipment reliability upgrade is not critically important from a PRA standpoint. However, the Control Room operators must also have confidence in the reliability of their instruments in order to make timely decisions on such emergency-manual operation of equipment. Since such safety-related indication instrumentation circuits are also dependent on these transmitters, a moderate impact relative to nuclear safety is assigned to this project (0.5 x 32). In addition, the replacement equipment is expected to be inherently more reliable during normal operations, thus potentially increasing plant operational availability (0.2 x 12). Also, new components with increased reliability will reduce overall maintenance requirements. Moreover, since the approach being taken is to replace the equipment in an efficient, comprehensive manner rather than piecemeal, worker productivity and error avoidance will be enhanced, thus resulting in general operational and maintenance enhancements (0.5 x 8).

Economic Aspects: This project contributes significantly to equipment reliability and operator confidence in Control Room indications important to safety. The upgraded equipment is also expected to require less maintenance in the future.

Related Standards: This project primarily impacts Work Management Policies for operating parameters and material condition. The regulatory commitment to upgrade the level of electrical equipment EQ is met by this project. When the project is completed, the ability of important plant instrumentation to continue to perform design safety functions under adverse environmental conditions will be significantly enhanced. This project provides a comprehensive and coordinated approach to meeting these requirements in a systematic manner so that design life limits for these instruments are not exceeded; minimizes maintenance and testing complexity that would result from a piecemeal approach; allows savings in updates for design configuration drawings, training program materials, and maintenance, test, and operating procedures.

Other Considerations: The Rosemount transmitters in Unit 1 have been upgraded. Unit 2 work remains. Most Unit 2 related equipment will be replaced during an outage (B211R1).

III. CONCLUSION

Rosemount transmitters are critical to level and flow instrumentation and will be upgraded to environmental qualification requirements in an expeditious manner. Unit 1 work is complete and Unit 2 work is in progress. Based on the project information available at this time, the project will continue as one of the highest priority plant upgrades.