United States Nuclear Regulatory Commission - Protecting People and the Environment

ACCESSION #: 9605300013

GE Nuclear Energy
General Electric Company
175 Curtner Avenue, San Jose, CA 95125
May 242 1996
96-04NRC.DOC
MFN 074-96
 
Subject: 10CFR Part 21, Reportable Condition, Safety Limit MCPR Evaluations
 
Reference: NEDE-24011-P-A-11, GESTAR II: General Electric Standard Application for Reactor Fuel, November 17, 1995.
This letter is to inform the NRC of a reportable condition per 10 CFR Part 21.
In the course of calculating a cycle-specific Safety Limit Minimum Critical Power Ratio (MCPR), it was determined that the GESTAR II (Reference) generic calculated Safety Limit MCPR may be non-conservative when applied to some actual core and fuel designs.
The NRC (Office of Nuclear Reactor Regulation, Reactor Systems Branch)was informed of this condition by telephone on March 27, 1996. A letter documenting this telephone call was sent to the NRC staff on March 29. On April 17, GE met with the NRC to present the results of calculations performed. Short-term and intermediate-term actions were discussed. This meeting was followed by a letter from R. J. Reda (GE) to Document Control Desk (L. E. Phillips-NRC), NRC/GE Meeting re: Safety Limit MCPR Calculation, MFN-051-96, April 22, 1996. The NRC subsequently performed an inspection (Inspection No. 99900003/96-01) of the GE facility in Wilmington, May 6-10.
GE has kept all BWR utilities using GE fuel and applying the GESTAR licensing basis informed of this condition. All affected utilities have been notified immediately of any changes to their Safety Limit MCPR. Actions are: continuing to address this condition as specified the Attachment.
Very truly yours,

M. A. Smith, Manager
Safety Evaluations Project
M/C 187,(408) 925-1019

cc: G. C. Cwalina (NRC-NRR/DOTS/TSIB)
R. C. Jones, Jr. (NRC-NRR/DSSA/SRXB)
L. E. Phillips (NRC-NRR/DSSA-/SRXB)
J. S. Armijo
T. M. Hauser
R. J. Reda
M. J. Sependa
PRC File


Attachment

Reportable Condition

(i) Name and address of the individual informing the Commission: M. A. Smith, Manager, Safety Evaluations Project, GE Nuclear Energy, 175 Curtner Avenue, San Jose, CA 95125.
(ii) Identification of the facility, the activity, or the basic component supplied for such facility or such activity within the United States which falls to comply or contains a defect:

Each BWR containing GE fuel and applying the GESTAR licensing basis may have a non-conservative Safety Limit MCPR. Each BWR is being analyzed to determine if the plant technical specification Safety Limit MCPR is compliant.

(iii) Identification of the firm constructing the facility or supplying the basic component which fails to comply or contains a defect: GE Nuclear Energy, Wilmington, North Carolina.
(iv) Nature of the defect or failure to comply and safety hazard which is created or could be created by such defect or failure to comply:
The Safety Limit MCPR is a specified acceptable fuel design limit as defined by General Design Criteria 10 of 10CFR 50 Appendix A. The Safety Limit MCPR is applied to ensure fuel cladding integrity is not lost as a result of over-heating. The Safety Limit MCPR defiles the minimum allowable critical power ratio (CPR) at which 99.9 percent of the rods in the core are expected to avoid boiling transition during the most limiting anticipated operational occurrence (AOO).
The Safety Limit MCPR is determined for each fuel design under the conditions specified by NEDE-24011-P-A-11, GESTAR II: General Electric Standard Application for Reactor Fuel, November 17, 1995, using the calculational methodology defined in NEDO-10958-A, General Electric BWR Thermal Analysis Basis (GETAB): Data, Correlation, and Application, January 1977.
Statistical analyses are performed which provide Safety Limit MCPR values applicable for each GE fuel (product line) design. The statistical procedure, when combined with the conditions set forth in Section 1 of GESTAR II, incorporates conservatisms as a mechanism to ensure that the statistical analysis is applicable to the range of BWR/2-6 initial and reload core cycles.
Recent analyses have indicated that the Safety Limit MCPR calculated on a generic basis with the GE methodology may be non-conservative when applied to some actual core and fuel designs.
GE has initiated action to evaluate the adequacy of the generic Safety Limit MCPRs for all plants using the GESTAR licensing basis. Such evaluations are being performed using the cycle-specific power distributions while applying the generic, conservative uncertainties. Selected analyses have shown that if realistic uncertainties were employed, the Safety Limit MCPR would be bounded by the GESTAR generic analyses.
(v) The date on which the information of such defect or failure to comply was obtained: March 28, 1996.
(vi) In the case of a basic component which contains a defect or failure to comply, the number and locations of all such components in use at, supplied for, or being supplied for one or more facilities or activities subject to the regulations in this part: All operating BWRs using, the GESTAR licensing basis (see Table 1).
(vii) The corrective action which has been, is being, or will be taken; the name of the individual or organization responsible for the action; and the length of time that has been or will be taken to complete the action:
Evaluated cycle-specific Safety Limit MCPRs for 23 of the 29 GE fueled BWRs in the U. S. using the currently approved GETAB uncertainties GE Nuclear Energy Action complete
Evaluate remaining GE fueled BWRs. GE Nuclear Energy June 14, 1996
Issue revised Supplemental Reload Licensing Reports to reflect changed Safety Limit MCPR and corresponding Operating Limit MCPR. GE Nuclear June 21, 1996
Amend GESTAR to make cycle-specific checks a routine Energy part of the standard reload licensing process. GE Nuclear June 28, 1996
Submit licensing topical report to the NRC to obtain improved Safety Limit MCPR analysis uncertainties. GE Nuclear June 28, 1996
(viii) Any advice related to the defect or failure to comply about the facility, activity, or basic component that has been, is being, or will be given to purchasers or licensees:
1. GE informed all licensees in writing of this generic condition, April 2-3, 1996.
2. GE provided minutes of the April 17, 1996 NRC meeting to the licensees on April 18. Also, potentially impacted licensees were informed by letter and advised to take administrative action to assure conformance to the revised limit and to notify the NTRC.
3. GE is providing correspondence to each licensee with verified changes needed in the Safety Limit MCPR for their plant(s). Impacted licensees are being advised to take immediate administrative action to increase the Operating Limit MCPR. Impacted utilities should consider notification of the NRC under 10CFR50.72 requirements.
4. GE is notifying licensees that upon receipt of the revised Supplemental Reload Licensing Report, the Core Operating Limits Report should be revised and a technical specification change submitted to the NRC that revises the Safety Limit MCPR.
5. GE will include in its notification to licensees that, after the licensing topical report to the NRC to obtain improved Safety Limit MCPR analysis uncertainties is reviewed and approved by the NRC, another technical specification change will be required to implement less conservative Safety Limit MRPRs that may result.


Attachment

Table 1 "Summary of Cycle Specific SLMCPR Evaluations".

Plant Cycle Evaluated SLMCPR Licensed SLMCPR
Oyster Creek 15 under evaluation 1.07
Nine Mile Point 14 1.10 1.07
pilgrim 11 1.06* 1.07
Monticello 18 1.08 1.07
Millstone 16 1.07* 1.07
Quad Cities 1 15 1.02 1.07
Quad Cities 2 14 1.05 1.07
Browns Ferry 2 9 1.09 1.07
Browns Ferry 3 7 1.06 1.07
Vermont Yankee 18 1.07 1.07
Cooper 17 1.05 1.06
Fitzpatrick 12 1.08 1.07
Brunswick 2 12 1.09 1.09
Brunswick 1 10 1.07 1.07
Duane Arnold 14 1.07 1.07
Peach Bottom 2 11 1.06* 1.07
Peach Bottom 3 11 1.08* 1.07
Hatch 1 17 1.06 1.07
Hatch 2 13 1.08 1.06
Hope Creek 7 1.08 1.07
Fermi 2 5 1.07 1.07
Limerick 2 4 1.10 1.07
Limerick 1 7 1.09 1.09
LaSalle 1 8 1.06 1.07
LaSalle 2 7 1.05 1.07
NineMile Point 2 5 1.10 1.07
River Bend 7 1.10 1.07
Clinton 6 1.08* 1.07
Perry 6 1.09 1.07

*Preliminary estimate


GENERAL INFORMATION or OTHER EVENT NUMBER: 30539
LICENSEE: GE NUCLEAR ENERGY NOTIFICATION DATE: 05/24/96
CITY: SAN JOSE REGION: 4 NOTIFICATION TIME: 17:02 [ET]
COUNTY: STATE: CA EVENT DATE: 03/28/96
LICENSE#: AGREEMENT: Y EVENT TIME: 00:00[PDT]
DOCKET: LAST UPDATE DATE: 05/24/96
NRC NOTIFIED BY: NOEL SHIRLEY NOTIFICATIONS
IQ OPS OFFICER: BOB STRANSKY VERN HODGE NRR
EMERGENCY CLASS: NOT APPLICABLE
10 CFR SECTION: CDEF 21.21(b)(2) DEFECTS/NONCOMPLIANCE

EVENT TEXT

GESTAR II GENERIC SAFETY LIMIT MINIMUM CRITICAL POWER RATIO (MCPR)MAY BE NONCONSERVATIVE WHEN APPLIED TO SOME CORE AND FUEL DESIGNS.

THE FOLLOWING IS TEXT OF A FACSIMILE SUBMITTED BY THE VENDOR:

"THE SAFETY LIMIT MCPR IS A SPECIFIED ACCEPTABLE FUEL DESIGN LIMIT AS DEFINED BY GENERAL DESIGN CRITERION 10 OF 10CFR50 APPENDIX A. THE SAFETY LIMIT MCPR IS APPLIED TO ENSURE FUEL CLADDING INTEGRITY IS NOT LOST AS A RESULT OF OVERHEATING. THE SAFETY LIMIT MCPR DEFINES THE MINIMUM ALLOWABLE CRITICAL POWER RATIO (CPR) AT WHICH 99.9 PERCENT OF THE RODS IN

THE CORE ARE EXPECTED TO AVOID BOILING TRANSITION DURING THE MOST LIMITING ANTICIPATED OPERATIONAL OCCURRENCE (AOO).

THE SAFETY LIMIT MCPR IS DETERMINED FOR EACH FUEL DESIGN UNDER THE CONDITIONS SPECIFIED BY NEDE-24011-P-A-11, "GESTAR II: GENERAL ELECTRIC STANDARD APPLICATION FOR REACTOR FUEL, NOVEMBER 17, 1995, USING THE CALCULATIONAL METHODOLOGY DEFINED IN NEDO-10958-A, "GENERAL ELECTRIC BWR THERMAL ANALYSIS BASIS (GETAB): DATA, CORRELATION AND APPLICATION." JANUARY 1977. STATISTICAL ANALYSES ARE PERFORMED WHICH PROVIDE SAFETY LIMIT MCPR VALUES APPLICABLE FOR EACH GE FUEL (PRODUCT LINE) DESIGN. THE STATISTICAL PROCEDURE, WHEN COMBINED WITH THE CONDITIONS SET FORTH IN SECTION 1 OF GESTAR II, INCORPORATES CONSERVATISMS AS A MECHANISM TO ENSURE THAT THE STATISTICAL ANALYSIS IS APPLICABLE TO THE RANGE OF 2WR/2-6 INITIAL AND RELOAD CORE CYCLES.

RECENT ANALYSES HAVE INDICATED THAT THE SAFETY LIMIT MCPR CALCULATED ON A GENERIC BASIS WITH THE GE METHODOLOGY MAY BE NONCONSERVATIVE WHEN APPLIED TO SOME ACTUAL CORE AND FUEL DESIGNS.

GE HAS INITIATED ACTION TO EVALUATE THE ADEQUACY OF THE GENERIC SAFETY LIMIT MCPRs FOR ALL PLANTS USING THE GESTAR LICENSING BASIS. SUCH EVALUATION ARE BEING PERFORMED USING THE CYCLE-SPECIFIC POWER DISTRIBUTIONS WHILE APPLYING THE GENERIC, CONSERVATIVE UNCERTAINTIES. SELECTED ANALYSES HAVE SHOWN THAT IF REALISTIC UNCERTAINTIES WERE EMPLOYED, THE SAFETY LIMIT MCPR WOULD BE BOUNDED BY THE GESTAR GENERIC ANALYSES."

THIS REPORT POTENTIALLY AFFECTS THE FOLLOWING UNITS: OYSTER CREEK, NINE MILE POINT 1 AND 2, PILGRIM, MONTICELLO, MILLSTONE 1, QUAD CITIES 1 AND 2, BROWNS FERRY 2 AND 3, VERMONT YANKEE, COOPER, FITZPATRICK, BRUNSWICK 1 AND 2, DUANE ARNOLD, PEACH BOTTOM 2 AND 3, HATCH 1 AND 2, HOPE CREEK, FERMI 2, LIMERICK 1 AND 2, LASALLE 1 AND 2, RIVER BEND, CLINTON, AND PERRY.*** END OF DOCUMENT ***


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