ML023310569
| ML023310569 | |
| Person / Time | |
|---|---|
| Site: | Hatch, Dresden, Peach Bottom, Browns Ferry, Nine Mile Point, Perry, Fermi, Hope Creek, Susquehanna, Columbia, Brunswick, Limerick, Clinton, Quad Cities, LaSalle  |
| Issue date: | 11/22/2002 |
| From: | Post J General Electric Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| MFN 02-091 | |
| Download: ML023310569 (9) | |
Text
11/'2212002 U.S. NuclearRegulatory Commission Operations Center Event Report Page I General Information or Other (PAR) Event# 39392 Rep Org: GENERAL ELECTRIC COMPANY Notification Date / Time: 11/22/2002 13:43 (EST)
Supplier: GENERAL ELECTRIC COMPANY Event Date/Time: 11/22/2002 11:43 (PST)
Last Modification: 11/22/2002 Region: 4 Docket #:
City: SAN JOSE Agreement State: Yes County: License #:
State: CA NRC Notified by: JASON POST (fax) Notifications: DALE POWERS R4 HQ Ops Officer: CHAUNCEY GOULD MOHAMED SHANBAKY R1 Emergency Class: NON EMERGENCY DAVID AYRES R2 10 CFR Section: BRENT CLAYTON R3 21.21 UNSPECIFIED PARAGRAPH GENERAL ELECTRIC IDENTIFIED THE STABILITY OPTION III PERIOD BASED DETECTION ALGORITHM T rmin SPECIFICATION HAS A DEFECT "Stability solution Option III is implemented in the Oscillation Power Range Monitor (OPRM). Each OPRM channel contains 18 to 33 OPRM cells (depending upon plant size). Each OPRM cell signal is summed from three to four closely spaced Local Power Range Monitor (LPRM) signals. Each OPRM cell signal is processed through the Option III detection algorithms to determine when a trip is required. Trip of one OPRM cell causes its OPRM channel to trip, and when sufficient OPRM channels trip (one-out-of-two taken twice, or two-out-of-four), a reactor scram is initiated to terminate the oscillation.
An OPRM trip is enabled for plant operation within the OPRM Armed Region as defined on the power/flow map.
The Armed Region extends from natural circulation to 60% of rated core flow. The licensing basis for the OPRM is to detect all expected oscillations within the OPRM Armed Region, and initiate a reactor trip to suppress the oscillation and provide Minimum Critical Power Limit (MCPR) safety limit protection.
GE LTR NEDO-31960-A, Supplement 1, "BWR Owners' Group Long- Term Stability Solutions Licensing Methodology (Supplement 1),n November 1995, describes the Option III detection algorithms. The Period Based Detection Algorithm (PBDA) provides licensing basis MCPR safety limit protection. Other algorithms provide defense-in-depth protection. The PBDA includes two parameters called Tmin and Tmax. The PBDA will not evaluate oscillations if the period is less than Tmin or greater than Tmax because these would not be indicative of an expected coupled neutronic/thermal - hydraulic instability. The LTR specifies that "typical" Tmin values are in the range of 1.0 to 1.4 seconds and "typical" Tmax values are in the range of 3.0 to 3.5 seconds.
The expected period of a coupled neutronic/thermal-hydraulic instability depends upon the fluid transit time through the core, and therefore depends upon core flow rate. This has been demonstrated in reactor operation and is predicted by GE computer models. At high core flow, the expected oscillation period is shorter. At low core flow rate, the expected oscillation period is longer. The intent of the OPRM is that Tmin and Tmax provide a wide range with adequate margin to the expected oscillation period for operation within the OPRM Armed Region so that
11122/2002 U.S. NuclearRegulatory Commission Operations Center Event Report Page 2 General Information or Other (PAR) Event # 39392 all expected coupled neutronic/thermal-hydraulic instabilities will be detected by the PBDA".
NOV 22 '02 11:43A:M GE NUCLEAR ENERGY P.1/7 GE Nuclear Energy Ectw Company Generala 175 CurnerAve.. San Jowe, CA 95125 November 22, 2002 02-1*NRC.DOC MFN 02-091 Document Control Desk United States Nuclear Regulatory Commission One White Flint North 11555 Rockville Pike Rockville, Maryland 20852-2738
Subject:
Reportable Condition Stability Option iM: Period Based Algorithm T.1,, Specification
Reference:
NEDO-31960-A, BWR Owners' Group Long-Term Stability Solutions Licensing Methodology (Supplement 1), November 1995 This letter provides notification of a reportable condition with the reference GE Nuclear Energy (GE) Licensing Topical Report (LTR) in accordance with §21.21(d). GE has identified that the stability Option III Period Based Detection Algorithm (PBDA) Tmjn specification is a defect as described below. GE recommends that T.mn be set to no higher than 1.2 seconds to ensure that oscillations are detected and suppressed as intended for stability solution Option M. GE cannot determine how each licensee with stability Option III has implemented Tread. Therefore, this information is provided as a Transfer of Information in accordance with §21.21(b) for each potentially affected licensee to evaluate if this concern applies to their plant.
Background, Stability Option HI Stability solution Option IM is implemented in the Oscillation Power Range Monitor (OPRM). Each OPRM channel contains 18 to 33 OPRM cells (depending upon plant size). Each OPRM cell signal is summed from three to four closely spaced Local Power Range Monitor (LPRMI) signals. Each OPRM cell signal is processed through the Option III detection algorithms to determine when a trip is required. Trip of one OPRM cell causes its OPRM channel to trip, and when sufficient OPRM channels trip (one-out-of two taken twice, or two-out-of-four), a reactor scram is initiated to terminate the oscillation.
An OPRM trip is enabled for plant operation within the OPRM Armed Region as defined on the power/flow map. The Armed Region extends from natural circulation to 60% of rated core flow. The licensing basis for the OPRM is to detect all expected oscillations
NOV 22 '02 11:43R1M GE NUCLEAR ENERGY P. 2/7 November 22, 2002 02-I ONRC.DOC MFN 02-091 within the OPRM Armed Region, and initiate a reactor trip to suppress the oscillation and provide Minimum Critical Power Limit (MCPR) safety limit protection.
GE LTPR NEDO-31960-A, Supplement 1, "BWR Owners' Group Long-Term Stability Solutions Licensing Methodology (Supplement 1)," November 1995, describes the Option III detection algorithms. The Period Based Detection Algorithm (PBDA) provides licensing basis MCPR safety limit protection. Other algorithms provide defense-in-depth protection. The PBDA includes two parameters called Ti,, and Ta.
The PBDA will not evaluate oscillations if the period is less than Tr, or greater than T.,.,
because these would not be indicative of an expected coupled neutronic/thermal hydraulic instability. The LTR specifies that "typical" Tmin values are in the range of 1.0 to 1.4 seconds and "typical" T,= values are in the range of 3.0 to 3.5 seconds.
The expected period of a coupled neutronic/thermal-hydraulic instability depends upon the fluid transit time through the core, and therefore depends upon core flow rate. This has been demonstrated in reactor operation and is predicted by GE computer models. At high core flow, the expected oscillation period is shorter. At low core flow rate, the expected oscillation period is longer. The intent of the OPRM is that Tmlin and T.,
provide a wide range with adequate margin to the expected oscillation period for operation within the OPRM Armed Region so that all expected coupled neutronic/thermal-hydraulic instabilities will be detected by the PBDA.
Basis for Reportable Condition GE has performed calculations of oscillation period for different power/flow conditions with the GE frequency domain code ODYSY- Representative results from these calculations are shown in Figure 1 (attached). Calculations with other models and plant experience support these results.
The lowest value specified in the "typical" range for T.,. is 3.0 seconds. The results in Fig*re 1 show that all periods are less than 3.0 seconds and that there is a significant margin between the nominal calculated periods to the 3.0 seconds value. Therefore, even if a plant uses the lowest "typical" value for T,., it is expected to be greater than the actual period. Therefore, the "typical" range specified in T., causes no safety concern.
The highest value in the specified allowable range for T ,, is 1.A seconds. The results in Figgure 1 show that at high core flow, the expected oscillation period is below 1.4 seconds. The margin to Tk of 1.4 second is not adequate since the use of this "typical" T,, value could lead to failure of the PBDA to detect an expected oscillation, Failure of automatic detection at this condition is not expected to result in fuel failures, but may lead to violation of the Technical Specification MCPR safety limit. This is considered to be a Reportable Condition on NEDO-31960-A, Supplement 1. GE analysis shows that for current licensed operation conditions, a generic Trzin value of 1.2 seconds provides adequate margin to expected oscillation periods.
GE does not have responsibility for the T, value used by each plant that has selected Option III. Furthermore, GE does not know if any licensee has developed a plant specific basis to support the T.in value used. Consequently, all Option III plants are 2
NOV 22 '02 11:44AM GE NUCLEAR ENERGY P. 3/7 November 22,2002 02-10NRC.DOC MEN 02-091 potentially affected and this is a Transfer of Information to all Option IMI plants under 10CFR21.
Corrective Action
- 1) Absent plant-specific justification of a higher value, the OPRM is not considered to be operable with a Ti. value greater than 1.2 seconds; T.,* should be set to 1.2 seconds or lower. With T, set to 1.2 seconds or lower, the OPRM is considered to be operable. However, GE recommends that plants consider using a value of 1.0 second to provide additional margin to the expected period range.
However, absent plant-specific justification, GE recommends using a T,, value of 3.5 seconds or higher to provide additional margin to the expected period range.
- 3) A tighter Txin/Tma. range may be justified based on plant-specific analysis and/or experience.
If you have any questions, please call me at (408) 925-5362.
Sincerely, Jason. S. Post, Manager Engineering Quality and Safety Evaluations cc: S. D. Alexander (NRC-NRRUDISPJPSIB) Mail Stop 6 F2 J. W. Foster (NRC-NRR/DISP/PSIB) Mail Stop 12 H2 J. F. Klapproth (GE-NE)
H. 1. Neems (GE-NE)
PRC File Attachments:
- 1. Figure 1. Expected Oscillation Period vs. Core Flow
- 2. Information per §21.21(d)(4)
- 3. Potentially Affected Plants 3
.2 1 November 22, 2002 02-1ONRC.DOC MFN 02-691 z
0 Attachment 1 - Figure 1. Expected Oscillation Period vs. Core VFlow N
I-.
I-.
1 T T I T 1 P1 2.4 I t t I 4 0
rP1 2.2 1:1 2-a V
1.8 U.,
02 Q~
IL 1.6 1.
1.4 1.2 I
1.0 30 35 40 45 50 55 60 65
% Rated Core Flow
-U 4
NOV 22 '02 11:44AM GE NUCLEAR ENERGY P. 5/7 November 22, 2002 02-IONRC.DOC MFN 02-091 Attachment 2 - Information per §21.21(d)(4)
(i) Name and address of the individual informing the Commission:
Jason S. Post, Manager, Engineering Quality & Safety Evaluation, 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 fails to comply or contains a defect:
All stability solution Option Mi plants are potentially affected. These plants are listed in Attachment 3.
(iii) Identification of the firm constructing the facility or supplying the basic component which fails to comply or contains a defect:
GE Nuclear Energy, San Jose, California (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 specification of the T,, parameter in licensing topical report NEDO-31960 A, BWR Owners' Group Long-Term Stability Solutions Licensing Methodology (Supplement 1), November 1995 is defective. This report provides a "typical" range of values for T.i, as 1.0 to 1.4 seconds. However, plants may have been using this as a generically approved range. GE has determined that expected oscillation period may be less than 1.4 seconds for a portion of the power/flow operating domain where the Option III system is to be armed. If a plant used a Tm, value of 1.4 seconds and the actual oscillation period was less than 1.4 seconds, the oscillation would not be detected. Thus, automatic protection for the Minimum Critical Power Ratio (MCPR) Technical Specification safety limit would not be provided by the Option III system as intended. Fuel failures are not expected as many minutes are available for the operator to take action to mitigate this event.
(v) The date on which the information of such defect or failure to comply was obtained:
September 23, 2002 (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:
The potentially affected plants are listed in Attachment 2.
5
NOV 22 '02 11:45AM GE NUCLEAR ENERGY P. IS/7 November 22,2002 02-iONRC.DOC MFN 02-091 (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 (note, these are actions specifically associated with the identified Reportable Condition):
" All potentially affected licensees have been notified by a Transfer of Information per §21.21(b) on this date.
" Each potentially affected licensee must initiate action to determine if they are affected by this concern within their Part 21 program.
"o If a licensee is using Tmi, = 1.A seconds and does not have a plant specific justification for use of this value, the OPRM should be declared inoperable until the value is changed to Ti _<1.2 seconds, or a plant-specific justification for continued use of Tm =
1.4 seconds is completed.
"o If a licensee is using Ti, -<1.2 seconds, it is not necessary to declare the OPRM inoperable. However, it is recommended that the licensee consider reducing the value to 1-0 seconds
"* GE will modify the user's manual for plants which use the GE supplied Power Range Neutron Monitor to limit the T,,&, setting, with allowance to use a higher value if applicable, based on a plant-specific justification.
(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. Absent plant-specific justification of a higher value, Tain should be set to 1.2 seconds or lower. GE recommends that plants consider using a value of 1.0 second to provide additional margin to the expected period range.
- 2. The T,, value specified in the reference licensing topical report is not identified as being reportable because values over the entire "typical" range of 3.0 to 3.5 seconds will not prevent detection of expected oscillations. However, GE recommends using a value of 3.5 seconds or higher to provide additional margin to the expected period range.
- 3. A tighter range of values for TM and T,=, may be justified based on plant specific analysis and/or experience.
6
NOV 22 '02 i1:45AM GE NUCLEAR ENERGY P. 7/7 November 22, 2002 02-10NRC.DOC MFN 02-091 Attachment 3 - Potentially Affected Plants utility Plant x AmerGen Energy Co. Clinton AmerGen Energy Co. Oyster Creek x Carolina Power & Light Co. Brunswick I x Carolina Power & Light Co. Bnmswick 2 Constellation Nuclear Nine Mile Point 1 x Constellation Nuclear. Nine Mile Point 2 x Detroit Edison Co. Fermi 2 Dominion Generation Millstone 1 x Energy Northwest Columbia Entergy Nuclear Northeast FitzPatrick Entergy Nuclear Northeast Pilgrim Entergy Operations, Inc. Grand Gulf Enzergy Operations, Inc. River Bend Entergy Nuclear Northeast Vermont Yankee Exelon Generation Co. CRIT Facility x Exelon Generation Co. Dresden 2 x Exelou Generation Co. Dresden 3 x Exclon Generation Co. LaSalle 1 x Exelon Generation Co. LaSalle 2 xX Exelon Generation Co. Limerick I x Exelon Generation Co. Limerick 2 Exelon Generation Co. Peach Bottom 2 x Exelon Generation Co. Peach Bottom 3 x Exelon Generation Co. Quad Cities I x Exelon Generation Co. Quad Cities 2 x FirstEnergy Nuclear Operating Co. Perry I Nebraska Public Power District Cooper Nuclear Management Co. Duane Arnold x Nuclear Management Co. Monticello Pooled Equipment Inventory Co. PIM PPL Susquebanna LLC. Susquehanna 1 x PPL Susquehanna LLC Susquehanna 2 x Public Service Electric & Gas Co. Hope Creek x Southern Nuclear Operating Co. Hatch 1 x Southern Nuclear Operating Co. Hatch 2 x Tennessee Valley Authority Browns Fenry I Tennessee Valley Authority Browns Ferry 2 x Tennessee Valley Authority Browns Ferry 3 7