I. PURPOSE AND SCOPE

The purpose of this project is to install a new reactor vessel level indicating transmitter loop to the remote shutdown panel (RSP) to comply with 10 CFR 50 Appendix R, Section III.L.2.D and to meet the performance goals of the Alternate Shutdown Conformance Assessment (ASCA) Report, October 1984.

A new vessel level indicator will be mounted on the RSP with a range of -150 inches to +150 inches reactor water level. The indicator will obtain its signal from a new transmitter which will tie into the LT-N037 vessel level transmitter instrument lines. It will be designed to provide indication of vessel level below that currently provided (i.e., below +10 inches).

The new level transmitter, 3-valve manifold, and tubing sensing lines will be mounted on the H21-P010 instrument rack in the Reactor Building, elevation 20'. The final tie to the sensing lines of the B21-LT-N037 transmitter, which is also located on the H21-P010 instrument rack, will be completed during a refueling outage. New cabling and conduit will be installed from the RSP to the H21-P010 instrument rack.

The success criteria of this project is to close out the 10 CFR 50, Appendix R exception and provide reactor water level indication below the current +10 inch capability at the RSP in order to be able to safely shutdown the reactor in the event of a fire in the Main Control Room.

II. EVALUATION

Schedule Index: 16 - Use of the RSP is credited in a PRA scenario involving flooding of the cable spreading room (i.e., failing battery chargers) and failure of DC power. Failure to monitor reactor level using the RSP indicators could result in up to a 4 percent increase in core damage frequency. Therefore, this initiative does significantly affect the accuracy of a system important to safety, because the operator may have to take corrective action based on indicated RSP reactor level indication. A nuclear safety scaling factor of 0.5 was assigned to this initiative (0.5 x 32). Future external event analyses (e.g., fire) may cause a higher weight in the nuclear safety scaling factor with respect to RSP changes.

This initiative is also a plant enhancement because it provides the RSP operator with a more accurate indication of reactor level and consequently prevents incorrect operator actions based on previously inaccurate reactor level indication (0.2 x 8). Finally, this project would result in a net dose expenditure with no future dose savings for the remaining life of the plant. Therefore, there is a low negative impact on ALARA (-0.2 x 9).

Economic Aspects: There will be a small increment of continuing costs as a result of the periodic instrument loop calibrations required. The net expected benefits of this project cannot be clearly defined because the modification improves the reactor level indication at the RSP, which is only employed under narrowly defined conditions.

Related Standards: The applicable Work Management Policies are those for material condition and operating parameters.

Other Considerations: All of the work with the exception of the final tie-in of the new instrument tubing to the B21-N037 transmitter can be completed while on-line. The final tie-in will require a system outage for the "B" Loop of RHR. The work is scheduled for refueling outages B109R1 for Unit 1 and B211R1 for Unit 2. This project is a CP&L commitment for RSP instrumentation as identified in the ASCA report dated October 1984.

III. CONCLUSION

This project is required to comply with 10 CFR 50, Appendix R, and is to be completed during the B109R1 and B211R1 outages. This project satisfies the performance goal of the Alternate Shutdown Conformance Assessment report.