ML20044H101
| ML20044H101 | |
| Person / Time | |
|---|---|
| Site: | Clinton  |
| Issue date: | 05/25/1993 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20044H091 | List: |
| References | |
| NUDOCS 9306070391 | |
| Download: ML20044H101 (4) | |
Text
_.
[ "%g j. k
)' k C
UNITED STATES j
NUCLEAR REGULATORY COMMISSION
'; Qg y
WASHINGTON. D C. 20556-0001 y~j SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 75 TO FACILITY OPERATING LICENSE NO. NPF-62 ILLIN0IS POWER COMPANY. ET AL.
CLINTON POWER STATION. UNIT NO. 1 DOCKET NO. 50-461 F
1.0 INTRODUCTION
By letter dated February 11, 1993, the licensee stated that a different (but NRC-approved) fuel design (GE10) would be utilized during the fourth refueling outage currently scheduled to begin September 26, 1993.
In order to support this outage, the following technical specification changes were proposed:
Technical Specification 5.3.1, " Fuel Assemblies," provides a fuel design feature description which includes information of the number of fuel and water rods, cladding material, active fuel length and bundle enrichments.
This description will change with new fuel designs.
In addition, this description will change if fuel reconstitution is necessary or if lead-use assemblies are used.
In order to make the fuel design description more generic to allow the use of NRC-approved designs, the NRC issued Supplement 1 to Generic Letter 90-02, " Alternative Requirements for Fuel Assemblies in the Design Features Section of Technical Specifications." This correspondence provided generic wording to be used in the fuel design i'
feature description so that NRC-approved fuel designs could be utilized without the burden of amending the technical specifications.
The licensee has proposed incorporating the wording provided by the staff.
Technical Specification 5.3.2, " Control Rod Assemblies," provides a description stating that the control rods will consist, in part, of boron carbide powder surrounded by a cruciform shaped _ stainless steel sheath.
Such wording precludes the use of any other neutron absorbing material in control rod design.
Subsequent to licensing the Clinton Power Station (CPS), the NRC has reviewed and approved the use of hafnium control rods at BWR facilities.
In order to use the new or upgraded control rod designs being offered by nuclear vendors, the licensee has proposed revising Specification 5.3.2 to permit the use of hafnium control rods.
Technical Specification 3.3.1, " Reactor Protection System Instrumentation," specifies the value of the simulated thermal power 9306070391 930525 PDR ADOCK 05000461 P
pyg
.q '
time constant for the Average Power Range Neutron Monitors. This value is dependent upon the fuel pellet diameter and will change with' different fuel designs incorporating 9x9 or 10x10 arrays of fuel:
pins.
(The CPS currently has 8x8 fuel pin arrays.) The NRC issued Generic Letter 88-16, " Removal of Cycle-Specific. Parameter _ Limits -
from the Technical Specifications," to permit core reloads using'NRC-approved methods without the burden of amending the technical-i specifications.
This correspondence permitted transferring cycle-specific parameters from the technical specifications to'the Core Operating Limits Report (COLR).
By changing fuel designs, the simulated thermal power time constant will change. Therefore, consistent with the guidance provided in the generic letter, the licensee has proposed transferring the simulated thermal power time-constant from the technical specifications to the COLR.
2.0 EVALUATION Technical Specification 5.3.1. " Fuel Assemblies" The fuel assembly description found in technical specification 5.3.1 is somewhat detailed and is limited to fuel assemblies incorporating an 3x8 i
fuel pin array.
Descriptive information on cladding material, active fuel length and bundle enrichments limits the licensee's ability to change fuel' designs.
In order to take advantage of new and improved fuel. assembly -
designs incorporating a 9x9 or 10x10 fuel pin array, a technical-i specification change would be necessary.
For this reason,~the licensee proposes to revise the fuel design requirements to be more generic but still require that these designs be developed and analyzed using NRC-approved codes and methode.
On July 3), 1992, the staff issued Supplement 1 to Generic Letter 90-02 as a line-item improvement to accommodate limited fuel reconstitution based on NRC-approved generic topical reports.
The generic letter. proposed wording to be used by licensees to describe fuel assemblies that incorporate the use of NRC-approved applications of fuel rod configurations.
In the licensee's letter of February 11, 1993, the licensee adopted the descriptive wording as suggested by the staff. 'The wording is less restrictive than that currently found in the CPS tbchnical specifications and will permit the licensee to utilize new and improved. fuel designs.
Therefore, since the licensee's proposal is consistent with the staff's position, the proposed change is acceptable.
Technical Specification 5.3.2. " Control Rod Assemblies" The control rod assembly description found in technical specification 5.3.2 limits the licensee to control rods that consist of stainless steel tubes containing 143.70 inches of boron carbide powder surrounded by a cruciform shaped stainless steel sheath, The lack of a reference to other neutron-i absorbing materials precludes the use of cor. trol rods having designs utilizing a different composition of materials such as hafnium.
Subsequent to the licensing of the CPS, the NRC has reviewed and approved control rod
~
e
i l
designs for BWR facilities using hafnium.
Hafnium control rods have certain advantages over baron carbide including reduced stress corrosion cracking due to irradiation effects and a longer ' reactivity life.
- Overall, i
this leads to a longer control rod blade life.
In their letter of February 11, 1993, the licensee proposed rewording Specification 5.3.2 to permit the use of boron carbide powder and/or hafnium metal in the control rod assemblies.
In addition, the, licensee committed to use control rod assemblies that had been approved by the NRC 3
for use in BWR facilities.
Since the staff has previously found hafnium to be an acceptable neutron-absorbing material for control rod assemblies in
~
BWR facilities and the licensee has committed to use a design approved by_
the staff, the proposed change is acceptable.
Technical Snecification 3.3.1. " Reactor Protection System Instrumentation" Generic Letter 88-16, " Removal of Cycle-Specific Parameter Limits from Technical Specifications," discussed the merits of processing license amendments required for each fuel cycle to update the values of cycle-specific parameter limits found in technical specifications.
The staff stated that the processing of changes to technical specifications that are developed using an NRC-approved methodology is an unnecessary burden on licensee and NRC resources.
The generic letter provided guidance for licensees to remove all cycle-specific parameters from the technical specifications and transfer them to a Core Operating Limits Report (COLR).
The Clinton licensee incorporatea the staff's guidance of Generic Letter 88-16 and removed the cycle-specific parameters.
As described in the licensee's letter of February 11, 1993, the simulated thermal power time constant is dependent, in part, on the fuel pellet diameter.
The value decreases with decreased fuel pellet diameter as it takes less time for the heat to travel through the fuel'to the outer-surface.
CPS Technical Specification Table 3.3.1-2, " Reactor Protection System Response Times," and Table 4.3.1.1-1, " Reactor Protection System Instrumentation Surveillance Requirements," reference a simulated thermal power time constant based on a 8x8 fuel pin array.
By incorporating new L
fuel designs having 9x9 or 10x10 fuel pin arrays, the fuel pellet diameter will decrease resulting in a revised simulated thermal power time constant.
Consistent with the staff's guidance of Generic Letter 88-16, the licensee has proposed removing the simulated thermal power time constant from the i
technical specifications and transferring it to the COLR.
The licensee has 1
also proposed modifying the Bases section accordingly.
These changes will preclude both the licensee.and NRC staff from processing license amendments j
associated with changes in fuel designs.
Since fuel designs will be limited to those approved by the staff and the proposal is consistent with previous NRC guidance, the staff finds.the licensee's proposal acceptable.
i r
i
.. - -. - - ~,
r
3.0 STATE CONSULTATION
5 In accordance with the Commission's regulations, the' Illinois State-official was notified of the proposed issuance of the amendment.
The State t
official had no comments.
4.0 ENVIRONMENTAL CONSIDERATION
This amendment changes a requirement with respect to installation or use of a facility component located within the restricted area ~as defined in 10 CFR Part 20.
The NRC staff has determineo 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 i
exposure.
The Commission has previously issued a-proposed finding that the amendment involves no significant hazards consideration and there.has been i
no public comment on such finding (58 FR 16862). Accordingly, the amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9).
Pursuant to 10 CFR SI.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendment.
5.0 CONCLUSION
t The staff 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:
Douglas V. Pickett, NRR-l Date: May 25, 1993 i
P f
.,