NUREG-1537, Part 2 - NRC

HEU TO LEU CoNvERSoN
*Acceptable changes to technical specifications and their bases have been
proposed to accommodate the conversion from HEU fuel.
4.6 Functional Design of Reactivity Control Systems
Areas ofReview
Although not likely to be affected by the conversion to LEU,' the reviewer should
evaluate the design features of the reactivity control systems to verify that they
include redundancy, diversity, and automatic protective action." The reactivity
control system should provide sufficient reactivity worths and response times 'for
the fUll range of operation and Section 13 postulated accident conditions. The
reviewer should examine rod drive speeds, reactivity change rates, and total
reactivity worths. Instrumentation for control and position indication, safety
wiring and circuitry for isolation and independence of control, and the functions of
interlocks and prohibits should also be reviewed. The reviewer should compare
the control functions for the HEU- and proposed LEU-fueled reactors. If
differences in the operating characteristics of the two reactors require
modifications to the reactivity control systems, the design bases and modifications
should be reviewed and evaluated. Most conversions from HEU to LEU fuel
should not require modifications to the systems, functional capability, or technical
specifications for the reactivity control systems. However, any proposed changes
in the technical specifications and their bases should be reviewed and verified.
This section should be reviewed in conjunction with Sections 4.2, 4.5, 7, and 13.
Acceptance Criteria
Acceptance criteria should be based on the following considerations 'The existing
or modified reactivity control systems will be acceptable if no`new safety or
operational issues are raised by the fuel conversion, and analysesand' discussions
confirm that the LEU-fueled reactor is comparable'to the BEU-fueled reactor in
that it can be controlled and shut down with no significant reduction in reliability,
response times, reactivity response, and redundancy, for the full range of
operations and Section 13 postulated accident-conditions. Additional general
guidance may be found in ANSI/ANS 15.15 and ANSIANS 15.20 (drafi).
Selected reactivity control system functions and characteristics should be verified
as outlined in Section 12 on startup testing.
REV. 0,2/96 I9 SmNmUW REVIEW PLAN
REV. O. 2/96 -19- STANDARD REviEwPLAN