ML14339A811
Text
McGuire Units 1 and 2 B 3.4.17-1 Revision No. 115 RCS LoopsTest Exceptions B 3.4.17 B 3.4 REACTOR COOLANT SYSTEM (RCS)
B 3.4.17 RCS LoopsTest Exceptions BASES BACKGROUND The primary purpose of this test exception is to provide an exception to LCO 3.4.4, "RCS LoopsMODES 1 and 2," to permit reactor criticality under no flow conditions during certain PHYSICS TESTS (natural circulation demonstration, station blackout, and loss of offsite power) to be performed while at low THERMAL POWER levels.Section XI of 10 CFR 50, Appendix B (Ref. 1), requires that a test program be established to ensure that structures, systems, and components will perform satisfactorily in service. All functions necessary to ensure that the specified design conditions are not exceeded during normal operation and anticipated operational occurrences must be tested. This testing is an integral part of the design, construction, and operation of the power plant as specified in GDC 1, "Quality Standards and Records" (Ref. 2).
The key objectives of a test program are to provide assurance that the facility has been adequately designed to validate the analytical models used in the design and analysis, to verify the assumptions used to predict plant response, to provide assurance that installation of equipment at the unit has been accomplished in accordance with the design, and to verify that the operating and emergency procedures are adequate. Testing is performed prior to initial criticality, during startup, and following low power operations.
The tests will include verifying the ability to establish and maintain natural circulation following a plant trip between 10% and 20% RTP, performing natural circulation cooldown on emergency power, and during the cooldown, showing that adequate boron mixture occurs and that pressure can be controlled using auxiliary spray and pressurizer heaters powered from the emergency power sources.
APPLICABLE The tests described above require operating the plant without forced SAFETY ANALYSES convection flow and as such are not bounded by any safety analyses.
However, operating experience has demonstrated this exception to be safe under the present applicability.
RCS LoopsTest Exceptions satisfy Criterion 3 of 10 CFR 50.36 (Ref.
3).
RCS Loops - Test Exceptions B 3.4.17 BASES McGuire Units 1 and 2 B 3.4.17-2 Revision No. 115 LCO This LCO provides an exemption to the requirements of LCO 3.4.4.
The LCO is provided to allow for the performance of PHYSICS TESTS in MODE 2 (after a refueling), where the core cooling requirements are significantly different than after the core has been operating. Without the LCO, plant operations would be held bound to the normal operating LCOs for reactor coolant loops and circulation (MODES 1 and 2), and the appropriate tests could not be performed.
In MODE 2, where core power level is considerably lower and the associated PHYSICS TESTS must be performed, operation is allowed under no flow conditions provided THERMAL POWER is P-7 and the reactor trip setpoints of the OPERABLE power level channels are set 25% RTP. This ensures, if some problem caused the plant to enter MODE 1 and start increasing plant power, the Reactor Trip System (RTS) would automatically shut it down before power became too high, and thereby prevent violation of fuel design limits.
The exemption is allowed even though there are no bounding safety analyses. However, these tests are performed under close supervision during the test program and provide valuable information on the plant's capability to cool down without offsite power available to the reactor coolant pumps.
APPLICABILITY This LCO is applicable when performing low power PHYSICS TESTS without any forced convection flow. This testing is performed to establish that heat input from nuclear heat does not exceed the natural circulation heat removal capabilities. Therefore, no safety or fuel design limits will be violated as a result of the associated tests.
ACTIONS A.1 When THERMAL POWER is the P-7 interlock setpoint 10%, the only acceptable action is to ensure the reactor trip breakers (RTBs) are opened immediately in accordance with Required Action A.1 to prevent operation of the fuel beyond its design limits. Opening the RTBs will shut down the reactor and prevent operation of the fuel outside of its design limits.
RCS Loops - Test Exceptions B 3.4.17 BASES McGuire Units 1 and 2 B 3.4.17-3 Revision No. 115 SURVEILLANCE SR 3.4.17.1 REQUIREMENTS Verification that the power level is < the P-7 interlock setpoint (10%) will ensure that the fuel design criteria are not violated during the performance of the PHYSICS TESTS. The Surveillance Frequency is based on operating experience, equipment reliability, and plant risk and is controlled under the Surveillance Frequency Control Program.
SR 3.4.17.2 The power range and intermediate range neutron detectors and the P-7 interlock setpoint must be verified to be OPERABLE and adjusted to the proper value. A COT is performed prior to initiation of the PHYSICS TESTS. This will ensure that the RTS is properly aligned to provide the required degree of core protection during the performance of the PHYSICS TESTS.
REFERENCES
- 1.
10 CFR 50, Appendix B, Section XI.
- 2.
10 CFR 50, Appendix A, GDC 1, 1988.
- 3.
10 CFR 50.36, Technical Specifications, (c)(2)(ii).