United States Nuclear Regulatory Commission - Protecting People and the Environment

Removal of Cycle-specific Parameter Limits from Technical Specifications (Generic Letter No. 88-16)


                                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. 
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