ML20212F321
| ML20212F321 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 10/22/1997 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20212F303 | List: |
| References | |
| NUDOCS 9711040256 | |
| Download: ML20212F321 (4) | |
Text
{{#Wiki_filter:.. wo og\\ UNITED STATES p s j NUCLEAR REGULATORY COMMISSION a wAswiwarow. o.c. somewoot %...../ SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 152 TO FACILITY OPERATING LICENSE NO. NPF-49 NORTHEAST NUCLEAR ENERGY COMPANY. ET AL. MILLSTONE NUCLEAR POWER STATION. UNIT NO. 3 DOCKET NO. 50-423
1.0 INTRODUCTION
By letter dated June 19, 1997,_the Northeast Nuclear Energy Company, et al. (the licensee), submitted-a request for changes to the Millstone Nuclear Power Statinn, Unit No. 3 Technical Specifications (T3). The proposed changes modify the definition of the constants associated with the Overtemperature Delta-T (OTAT) and Overpower Delta-T (0 PAT) Reactor Trip System Instrumentation setpoint calculators. The proposed TS revision redefines the numeric constants with either "s" or "2," modifies the NOTES to reflect hardware modifications that were made during construction, moves the AT, term from the right side to the left side of the OTAT and OPAT algorithms, rewords the definitions for clarity, and expands the Bases description.
2.0 BACKGROUND
On March 11, 1997, the staff approved Millstone Unit 3 TS Amendment No.134, which revised notations in Table 2.2-1, Reactor Trip System Instrumentation Trip Setpoints. Specifically, the amendment redefined time constants associated with NOTE 1: Overtem)erature AT and NOTE 3: Overpower AT in terms of inequalities. Previously, tie time constants were defined in a manner implying the terms must be set exactly to defined values. Millstone Unit 3 surveillances allow for a tolerance around individual values. These tolerances are equivalent to equipment accuracy specifications that are included in the Channel Statistical Allowance provided in WCAP-10991, Revision 4, Westinghouse Setpoint Methodology for Protection Systems, Millstone Nuclear Power Station Unit 3. Although nominal treatment is allowed for individual constants, surveillance procedures require the as left channel setpoints to trip at less than or equal to the setpoint defined by the OTAT and OPAT algorithms. 3.0~ EVALUATION 3.1 lable 2.2-1 NOTE 1: Overtemoerature AT (OTAT1 The licensee proposed to redefine constants K, K, and K with inequalities i 2 3 (2 or s) and expand the OTAT Bases description. The constants K, K, and K 3 3 3 9711040256 971022 PDR ADOCK 05000423 P-PDR
. are preset bias gains that compensate fur temperature and pressure effects on departure from nucleate boiling limits. The licensee's current practice is to treat numeric constant values utilized in the Overtemperature AT calculation as nominal settings and allow the instrumentation to be adjusted to within a calibration tolerance. As a result of the licensee's analysis and its discussions with Westinghouse, it was determined that the constants should be treated as limiting settings, thus, the instrumentation would then be adjusted conservatively with respect to these constants. The polarity of the inequality operator indicates the direction of conservatism. The use of inequalities to define numerical constants associated with OTAT is consistent with the Westinghouse Standard Technical Specifications, NUREG-1431. The Bases change adds clarification that the gains be set as close as possible to the values provided in NOTE 1 to be consistent with safety analysis assumptions. The staff finds the proposed changes acceptable as they are consistent with the guidelines of NUREG-1431. In addition, the licensee proposes to eliminate the terms involving time constants 7 and 7 from the equation for OTAT. The time constants, 7 and 7 3 6 3 6' are utilized in the lag compensators for AT and the measured T m, respectively. The associated functions generated by the lag compensators appear as [l/(1+7)] terms. In the current TS Table 2.2-1, the licensee has mathematically eliminated the time constants and the associatad terms by defining 7terms a equal to zero in the (1/(1+T)) terms. and 7 This makes the (1/(1+T))3 multiplier of one, which is conservative. The proposed changes reflect modifications that eliminated hardware that was not required. Thus, eliminating 7 and 7 and associated terms has no effect on the 3 OvertemperatureATtripcahculation. Therefore, the staff finds the proposed change acceptable. The licensee further proposes to clarify the definition of AT as loop-specific and to move the term from the right side of the equalion to the left side er the algorithm. The proposed change shows AT and AT as the ratio (AT/AT ) and is mathematically equivalent to the current nofation. The staff consid,ers this change editorial in nature and finds it acceptable. The licensee proposes to redefine terms with the word "is" instead of an equal sign. The proposed change is editorial in nature and consistent with NUREG-1431, Revision 1. The staff finds this change acceptable. 3.2 Table q.2-1 NOTE 3: Overoower AT (0 PAT) The licensee proposed to redefine constants K, K, and X with inequalities 4 3 6 (2 or s). The constants K, K, and K are preset bias gains that compensate 4 3 6 for temperature effects on departure from nucleate boiling limits, and the change in density flow and heat capacity of water. The licensee's current practice is to treat numeric constant values utilized in the Overpower AT calt.0ation as nomin&1 settings and allow the instrumentation to be adjusted to within a calibration tolerance. As a result of the licensee's analysis and its discussions with Westinghouse, it was determined that the constants should be treated as limiting settings, thus, the instrumentation would then be adjusted conservatively with respect to these constants. The polarity of the inequality operator indicates the direction of cor.servatism. The use of
. inequalities to define numerical constants associated with OPAT is consistent. with NUREG-1431. The staff finds the proposed changes acceptable as they are consistent with the guidelines of NUREG-1431. In addition, the licensee proposes to eliminate the terms t ' 7, and f (AI) 3 from the OPAT equation. The time constants, r and r, are utifized in,the lag compensators for AT and the measured T,, 3respectively. The associated functions generated by the lag compensators appear as [l/(1+r)) terms. In the current TS Table ?.2-1, the licensee _ has mathematically eliminated the time constants and the associated terms by defining 7 and 7 eoual to zero in the 3 6 (1/(1+r)) terms. This makes the [1/(1+r)) terms a multiplier of one, which is conservative. The proposed changes reflect modifications that elimir. i'd hardware that was not required. Thus, eliminating i and rg and associated termshasnoeffectontheOverpowerATtripcalcula}. ion, The licensee has mathematically eliminated f,(AI) from the expression by defining it to be zero for all AI (where al is the indicated difference between top and bottom detectors of the power range neutron ion chambers). Tne licensee defines f (AI) ts zero because the source of temperature and flux information is ibentical to that of the OTAT trip. Eliminating f AI) term has no effect on Therefore, the staff,(finds the proposed changes the Overpower AT calculation. acceptable. The licensee further proposes to clarify the definition of AT as loop-specificandtomovethetermfromtherightsideoftheequaliontotheleft side of the ec,uation. The proposed change shows AT and AT, as the ratio (AT/AT ) and is mathematically equivalent to the current notation. The staff consid,ers this change editorial in nature and finds it acceptable. The licensee proposes to redefine terms with the word "is" instead of an equal sign. The proposed change is editorial in nature and consistent with NUREG-1431, Revision 1. The staff finds this change acceptable. 3,3 Staff Cpnclusion The staff has reviewed the licensee's proposed changes to the TS to modify the descriptions of the OTAT and OPAT numeric constants and notes, reword definitions, move the AT term to the left side of the OTAT and OPAT algorithms,andexpandtheBasesdescription. The changes ensure that instrumentation adjustments will be conservative with respect to the safety analysis assumptions and are consistent with appropriate sections of WCAP-10991 and NUREG-1431. Based on the review of the licensee's submittal, the staff concludes that the above TS changes are acceptable.
4.0 STATE CONSULTATION
In accordance with the Commission's regulations, the Connecticut State official was notified of the proposed issuarco of the amendment. The State official had no comments. 5.0 ENVIRONMENTAL CONSIDERATIE The amendment changes a requirement with respect to installation or use of a facility component located within the restricted area as defined in 10 CFR
4 Part 20. -The NRC staff has determined that the amendment involves no significant increase-in the amounts, and no significant change in the types, of-any-effluents-that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure. 'The Commission has previously issued a proposed finding that the amendment involves no significant hazards consideration, and there has been no public comment on such finding (62 FR 40852 dated July 30,1997). Accordingly, the amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9). Pursuant to 10 CFR 51.22(b) no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendment.
6.0 CONCLUSION
'The Commission has concluded, based on the considerations discussed above, that: (1) there is reasonable assurance that the health and-safety of the public will not be endangered by operation in the proposed manner,-(2) such activities.will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public. Principal Contributor: A. Bryant Date: October 22, 1997 I r-a-. e-e =}}