Protecting People and the EnvironmentUNITED STATES NUCLEAR REGULATORY COMMISSION
UNITED STATES
NUCLEAR REGULATORY COMMISSION
WASHINGTON, D.C. 20555
October 3, 1988
TO ALL POWER REACTOR LICENSEES AND APPLICANTS
SUBJECT: REMOVAL OF CYCLE-SPECIFIC PARAMETER LIMITS FROM TECHNICAL
SPECIFICATIONS (GENERIC LETTER 88-16)
License amendments are generally required each fuel cycle to update the
values of cycle-specific parameter limits in Technical Specifications (TS).
The processing of changes to TS that are developed using an NRC-approved
methodology is an unnecessary burden on licensee and NRC resources. A
lead-plant proposal for an alternative that eliminates the need for a
license amendment to update the cycle-specific parameter limits each fuel
cycle was submitted for the Oconee plant with the endorsement of the Babcock
and Wilcox Owners Group. On the basis of the NRC review and approval of that
proposal, the enclosed guidance for the preparation of a license amendment
request for this alternative was developed by the NRC staff.
Generally, the methodology for determining cycle-specific parameter limits
is documented in an NRC-approved Topical Report or in a plant-specific
submittal. As a consequence, the NRC review of proposed changes to TS for
these limits is primarily limited to confirmation that the updated limits
are calculated using an NRC-approved methodology and consistent with all
applicable limits of the safety analysis. These changes also allow the NRC
staff to trend the values of these limits relative to past experience. This
alternative allows continued trending of these limits without the necessity
of prior NRC review and approval.
Licensees and applicants are encouraged to propose changes to TS that are
consistent with the guidance provided in the enclosure. Conforming
amendments will be expeditiously reviewed by the NRC Project Manager for the
facility. Proposed amendments that deviate from this guidance will require a
longer, more detailed review. Please contact the Project Manager if you have
questions on this matter.
Sincerely,
Dennis M. Crutchfield
Acting Associate Director for Projects
Office of Nuclear Reactor Regulation
Enclosure:
As stated
.
Generic Letter 88-16 Enclosure
GUIDANCE FOR TECHNICAL SPECIFICATION CHANGES
FOR CYCLE-SPECIFIC PARAMETER LIMITS
INTRODUCTION
A number of Technical Specifications (TS) address limits associated with
reactor physics parameters that generally change with each reload core.
requiring the processing of changes to TS to update these limits each fuel
cycle. If these limits are developed using an NRC-approved methodology, the
license amendment process is an unnecessary burden on the licensee and the
NRC. An alternative to including the values of these cycle-specific
parameters in individual specifications is provided and is responsive to
industry and NRC efforts on improvements in TS.
This enclosure provides guidance for the preparation of a license amendment
request to modify TS that have cycle-specific parameter limits. An
acceptable alternative to specifying the values of cycle-specific parameter
limits in TS was developed on the basis of the review and approval of a
lead-plant proposal for this change to the TS for the Oconee units. The
implementation of this alternative will result in a resource savings for the
licensees and the NRC by eliminating the majority of license amendment
requests on changes in values of cycle-specific parameters in TS.
DISCUSSION
This alternative consists of three separate actions to modify the plant's
TS: (1) the addition of the definition of a named formal report that
includes the values of cycle-specific parameter limits that have been
established using an NRC-approved methodology and consistent with all
applicable limits of the safety analysis, (2) the addition of an
administrative reporting requirement to submit the formal report on
cycle-specific parameter limits to the Commission for information, and (3)
the modification of individual TS to note that cyclespecific parameters
shall be maintained within the limits provided in the defined formal report.
In the evaluation of this alternative, the NRC staff concluded that it is
essential to safety that the plant is operated within the bounds of
cycle specific parameter limits and that a requirement to maintain the plant
within the appropriate bounds must be retained in the TS. However, the
specific values of these limits may be modified by licensees, without
affecting nuclear safety, provided that these changes are determined using
an NRC-approved methodology and consistent with all applicable limits of the
plant safety analysis that are addressed in the Final Safety Analysis Report
(FSAR). Additionally, it was concluded that a formal report should be
submitted to NRC with the values of these limits. This will allow continued
trending of this information even though prior NRC approval of the changes
to these limits would not be required.
The current method of controlling reactor physics parameters to assure
conformance to 10 CFR 50.36 is to specify the specific value(s) determined
to be within specified acceptance criteria (usually the limits of the safety
analyses) using an approved calculation methodology. The alternative
contained in this guidance controls the values of cycle-specific parameters
and assures conformance to 10 CFR 50.36, which calls for specifying the
lowest functional
.
Generic Letter 88-16 - 2 - Enclosure
performance levels acceptable for continued staff operation, by specifying
the calculation methodology and acceptance criteria. This permits operation
at any specific value determined by the licensee. using the specified
methodology, to be within the acceptance criteria. The Core Operating Limits
Report will document the specific value of parameter limits resulting from
licensee's calculations including any mid-cycle revisions to such parameter
values.
The following items show the changes to the TS for this alternative. A
defined formal report, "Core Operating Limits Report" (the name used as an
example for the title for this report), shall be added to the Definitions
section of the TS, as follows.
[CORE] OPERATING LIMITS REPORT
1.XX The [CORE] OPERATING LIMITS REPORT is the unit-specific document
that provides [core] operation limits for the current operating reload
cycle. These cycle-specific [core] operating limits shall be determined
for each reload cycle in accordance with Specification 6.9.X. Plant
operation within these operating limits is addressed in individual
specifications.
A new administrative reporting requirement shall be added to existing
reporting requirements, as follows.
[CORE] OPERATING LIMITS REPORT
[6.9-Xl [Core] operating limits shall be established and documented in
the [CORE] OPERATING LIMITS REPORT before each reload cycle or any
remaining part of a reload cycle. (If desired, the individual
specifications that address [core] operating limits may be referenced.)
The analytical methods used to determine the [core] operating limits
shall be those previously reviewed and approved by NRC in [identify the
Topical Report(s) by number, title, and date, or identify the staff's
safety evaluation report for a plant-specific methodology by NRC letter
and date]. The [core] operating limits shall be determined so that all
applicable limits (e.g., fuel thermal-mechanical limits, core
thermal-hydraulic limits, ECCS limits, nuclear limits such as shutdown
margin, and transient and accident analysis limits of the safety
analysis are met. The [CORE] OPERATING LIMITS REPORT, including any
mid-cycle revisions or supplements thereto, shall be provided upon
issuance, for each reload cycle, to the NRC Document Control Desk with
copies to the Regional Administrator and Resident Inspector.
Individual specifications shall be revised to state that the values of
cyclespecific parameters shall be maintained within the limits identified in
the defined formal report. Typical modifications for individual
specifications are as follows.
The regulating rods shall be positioned within the acceptable operating
range for regulating rod position provided in the [CORE]
OPERATING-LIMITS REPORT. (Used where the operating limit covers a range
of acceptable operation, typically defined by a curve.)
The [cycle-specific parameter] shall be within the limit provided in
the [CORE] OPERATING LIMITS REPORT. (Used were the operating limit has
a single point value.)
.
Generic Letter 88-16 - 3 - Enclosure
SUMMARY
The alternative to including the values of cycle-specific parameter limits
in individual specifications includes (1) the addition of a new defined term
for the formal report that provides the cycle-specific parameter limits, (2)
the addition of its associated reporting requirement so the Administrative
Controls section of the TS, and (3) the modification of individual
specifications to replace these limits with a reference to the defined
formal report for the values of these limits. With this alternative, reload
license amendments for the sole purpose of updating cycle-specific parameter
limits will be unnecessary.
