RBG-29308, Application for Amend to License NPF-47,deleting Condition 2.C.(4),Attachment 2,Item 1 Requirement to Install Addl Brace on CRD Hydraulic Control Units as Used in Qualification Testing.Fee Paid
| ML20206C233 | |
| Person / Time | |
|---|---|
| Site: | River Bend  |
| Issue date: | 11/09/1988 |
| From: | Deddens J GULF STATES UTILITIES CO. |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| Shared Package | |
| ML20206C237 | List: |
| References | |
| RBG-29308, NUDOCS 8811160172 | |
| Download: ML20206C233 (19) | |
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GULF STATES
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e ,ns , m uusm m, A?i A (c .i 5.;4 f )? b:'7 4 ):A?*if November 9,1988 RBG-29308 File Nos. G9.5, G9.42 U.S. Nuclear Regulatory Commission Document Control Desk Washington, D.C. 20555 Gentlemen:
River Bend Station - Unit 1 Docket No. 50-458 Gulf States Utilities (GSU) hereby files an application for an amendment to the River Bend Station Unit 1 Facility Operating License tipF-47, pursuant to 10CFR50.90. This apolication is filed to delete the License Condition 2.C.(4), Attachment 2, Item 1 requirement to install an additional brace on the control rod . drive hydraulic centrol units as used in the qualification testing. Further analysis using NRC accepted methods of the original dynamic testing demonstra tes that the hydraalic control units as installed are qualified at RBS for more than 40 years.
Pursuant to 10CFR170.12 GSU has enclosed a check in the amount of one-hundred and fifty dollars ($150.00) for the license amendment application fee. Your prompt attention to this application is appreciated.
Sincerel u
J.C. Deddens Senior Vice President River Bend Nuclear Group JCD, A / JD S/ch Attachment h
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PDR ADOCK 05000458 Qh1(I P PDC
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cc: U. S. Nuclear Regulatory Comission 611 Ryan Plaza Drive, Suite 1000 Arlington, TX 76011 NRC Resident Inspector P.O. Box 1051 St. Francisville, LA 70775 Mr. Walt A. Paulson Project Manager U. S. Nuclear Regulatory Comission Document Control Desk Washington, D.C. 20555 Mr. William H. Spall, Administrator Nuclear Energy Division Louisiana Dept. of Environmental Quality P.O. Box 14690 Baton Rouge, LA 70898 l
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- UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION STATE OF LOUISIANA )
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Docket No. 50-458 In the Matter of )
GULF STATES UTILITIES COMPANY )
(River Bend Station - Unit 1)
AFFIDAVIT J. C. Deddens, being duly sworn, states that he is a Senior Vice President of Gulf States Utilities Company; that he is authorized on the part of said company to sign and file with the Nuclear Regulatory Commission the documents attached hereto; and that all such documents are true and correct to the best of his knowledge, information and belief.
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ATTACfMENT 1 GULF STATES UTILITIES COMPANY RIVER BEND STATION DOCKET 50-458/ LICENSE NO. NPF-47 SEISMIC AND DYNAMIC QUALIFICATION OF SEISMIC CATEGORY 1 MECHANICAL AND ELECTRICAL EQUIPMENT LICENSING DOCUMENT INVOLVED: Operating License NPF-47 Item: License Condition 2.C.(4), Attachment 2. Item 1 REASON FOR REQUEST:
A change is being requested in accordance with 10CFR50.90 to delete the requirement for implementation of hardware modifications (e.g., braces) to the River Bend Station (RBS) control rod drive hydraulic control units (HCUs) as currently required by License Condition 2.C.(4), Attachment 2, item 1 of RBS Operating License NPF-47. The subject license condition currently requires that, prior to startup following the second refueling outage, an additional brace be installed as used in the qualification testing of the HCU. During the seismic qualification testing, using a test response spectrum which bounded the test BWR/6 conditions, the hanger holding the nitrogen cylinder on the HCU test assembly failed due to fatigue. As a result, an additional brace was installed on the HCU test assembly prior to the successful completion of the dynamic qualification tests.
Further evaluation of the qualification testing perfonned prior to the l hanger failure shows that the HCU configuration currently installed at RBS was successfully tested at accelerations that adequately envelop the durations, magnitudes and frequency centent of the RBS design upset and faulted condition loads. Therefore, GSU has determined that the HCUs are I qualified for more than 40 years for the seismic / dynamic conditions postulated to occur at RBS.
DESCRIPTION:
The control rod drive (CRD) hyd. al" system consists of two drive water pumps located in the northwr-* Niner of the fuel building on the 70 foot elevation; 145 hydra.alic control u, sits (one for each CRD) located in the containment building on the 114 foot elevation, 72 on the east sido and 73 on the west side; and the associated piping, valves and instrumentation necessary for proper operation of the system. System pressure, during system startup or after resetting a scram, charges the hydraulic scram Ncumulators to approximately 1800 psig. ,
Page 1 of 11
The HCU is a General Electric (GE) factory-assembled, engineered module of valves, tubing, piping, and stored water which controls a single CR0 by the application nf precisely timed sequences of pressure and flow to accomplish control and rapid insertion for reactor scram. Upon initiation of a reactor scram signal, the scram inlet and discharge valves open allowing the stored energy in the scru accumulator to rapidly insert the control rod into the reactor core.
The HCUs were originally qualified by GE as documented in Qualification Report NEDC-30820 dated January 1985 (Reference 1). This qualification was performed in accordance with Regulatory Guide 1.100 Revision 1 (Reference
- 6) and IEEE 344-1975 (Reference 5). However, during the dynamic testing of the HCU test assembly, the hanger holding the nitrogen cylinder failed due to fatigue.
The following tests were successfully conducted prior to the hanger failure:
(1) 90 minutes of vibration aging at 0.75 g input (one in each orthogonal axis), (2) 15 minutes random, multifrequency (RMF) testing biaxial excitation in thefront-to-backandverticaldirections,and(3}3 minutes 40 seconds RMF testing, biaxial excitation in the side-to-side and vertical directions. Testing was continued after repairing the test assembly by replacing the failed hanger and adding a brace and clamp around the bottom of the nitrogen cylinder. The remaining dynamic tests were successfully completed, and the functional adecuacy of the test assembly was verified during and after the simulated faulted condition loads (generic safety / relief valve (SRV), chugging (LOCA) and selsmic loading requirements of HCus). Seismic qualification of equipment by test is discussed in RBS Updated Safety Analysis Report (USAR) Section 3.7.2.1.68.
To validate the completed dynamic test results and support timely operating license review, GSU comitted to modify the HCus by adding an additional brace, similar to the one installed during the test, prior to startup following the second refueling outage. An imediate fix was not required because it was shown in Reference 1 that the unbraced HCus currently installed at RBS were qualified for a reduced service life of 4.4 years based on an estimated 200 SRV actuations (of 1800 expected for 40 year life) occurring at the test response spectra (TRS) level in addition to 3 upset and 1 faulted event. Interim opera tion was granted based on this justification and the current license condition to install the additional braces prior to startup following the second refueling outage was issued with the RBS low power operating license. There have been only 77 SRV actuations at RBS to date. The original redu;ed service life estimate was extremely conservative because it was based on only the successful 3 minutes 40 seconds of SRV aging RMF testing that occurred in the side-to-side and vertical test orientation before the failure of the nitrogen cylinder support hanger. The HCU assembly was also successfuliy tested for 90 minutes of vibration aging in each orthogonal axis and 15 minutes of SRV aging RMF testing in the front-to-back and vertical orientation prior to the fatigue failure of the hanger.
GSU also did not take credit for the significant margins that exist between the SRV aging RMF test response s (TRS) and the RBS unique SRV required response spectra (RRS) pectra(see atteched figures). The RMF TRS was established to envelop the required response spectra (RRS) for another BWR/6 Page 2 of 11
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reactor. The testing conducted by GE required that the TRS envelope the RRS developed at the HCU mounting locations for the test BWR/6 with adequate
-! margins. The RRS of the test BWR/6, and hence the TRS used in the dynamic -
) testing, is substantially higher than the unique RRS for SRV loading and i upset condition loading at the HCU mounting locations at RBS. As a result, the TRS for the seismic / hydrodynamic loads are substantially conservative !
l for RBS. Some of the differ ness which lead to this large difference l between the two RRS are.
i
- 1. Seismic design basis ground accelerations of 0.075 g for an !
, operational bases earthquake (OBE) and 0.15 g for a safe shutdown 4
earthquake (SSE) were used in developing the TRS. RBS is designed j for ground accelerations of 0.05 g during an OBE and 0.10 g during a
- SSE. ;
! 2. The structural support configuration for the HCUs at the test BWR/6 !
< is different from the RBS structural support configuration. For !
l example, the test BWR/6 supporting structure is anchoreo to the !
1 suppression pool flocr while the RBS HCU support structure is ;
located on a floor above the suppression pool. Therefore, the RBS !
supporting structure would be subjected to less suppression pool i I
swell loads than the test BWR/6. <
, I j 3. The test BWR/6 is designed with 19 SRVs while RBS is designed with j 16 SRVs. The larger amount of energy released by the increased 4
number of SRVs could result in larger structural responses and ;
1 therefore, result in a higher RRS for the test BWR/6 than that of '
RBS. ,
l j Because of the severity of the original qualification testing, an additional [
1 evaluation was conducted by GSU to detemine the actual number of stress ;
j cycles imposed on the HCU by the suaessful testing completed prior to the ;
- fatigue failure of the nitrogen cylinder hanger. The results of this design ;
i calculation concluded that the unbraced HCU units are seismically / l
! dynamically qualified at RBS for more than 40 years of life with a safety ;
l margin of 3.9. A sumary of this evaluation is discussed below. l i
i COMPARISON OF STRESS CYCLES - UNMODIFIED HCU CONFIGURATION TESTS vs. [
R 5 SPECIFIC DYN.AMIC LOAD REQUIREMENTS
)
i A comparison is made here between the equivalent stress cycles that were !
- imposed on the HCU test assembly during the successful dynamic testing prior l j to the fatigue failure of the nitrogen cylinder hanger and the stress cycles t 1 that are required from the RBS specific upset condition RRS loads (see Tab 1? !
- 1). In accordance with USAR Section 6A.17 and IEEE 344-1987, both values !
j are normalized to the same response magnitude, thus making the comparisons ,
- meaningful.
The HCU test assembly was tested by GE to 90 minutes of vibration aging
- along each orthogonal axis, separately, and then by random, multifrequency -
- (RMF) testing to simulate the specific seismic / hydrodynamic loads of the l test BWR/6. These tests represent a substantial overtesting when compared j i to the RBS specific design loads and testing requirements. Thus, an l
] equivalent number of stress cycles induced in the test HCU prior to the
! r Page 3 of 11 l
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, fatigue failure of the hanger (normalized to the RBS specific upset
- condition RRS magnitudes) was calculated.
The concept of developing the equivalence is based on Miner's theory of I
cumulative fatigue damage which is a standard industry practice and is i recommended in IEEE 344-1987 and the ASME !!! Code. Stated simply, two l points on the S-N (maximum cycles to failure vs. maximum stress) curve of a typical structural material are equivalent to each other when related by an
, exponential relationship. An average exponent of 2.5 (Reference IEEE 1
- 344-1987) was used to calculate the equivalence between the stress cycles i induced at the TRS and the equivalent stress cycles at the RBS upset i
i condition RRS. This is a conservative average exponent considering ASME '
Section !!!, Appendix II-1520, 1983 and 1986 Editions reconenend a less I conservative average exponent of 4.3 for cyclic testing of components. ;
2 Fatigue fF lure occurs when the cumulative usage factor 6pproaches unity. ,
This happened for the nitrogen cylinder Sanger at 3 minutes 40 seconds into ;
the second biaxial orientation RMF test.
3 For the calculation of equivalent stress cycles, it is important to identify j all the resonant frequencies in the vicinity 6f the nitrogen cylinder I l hanger. The transmissibility plots and l oca ti on *, of the accelerometers 1 mounted on the HCU test assembly are available in GE's test report !
NEDC-30820 (Reference 1). The minimuin difference between the accelerations i
) of the TRS and the RBS upset condition RRS at each of the resonant .
l frequencies was utilized to calculate the equivalent stress cycles at the f
EQUIVALENT S'RESS CYCLES INDUCED BY V!BRATION AGING TESTS i
j The equivalent stress cycles normalized to the RBS upset condition RRS j 1 induced from the 90 minute vibration aging tests at 0.75g input were ;
j calculated (Reference 2), resulting in 8000 equivalent stress cycles. The ,
! equivalent stress cycles for the vibrat%n aging tests were calculated as l l follows: $
l ll Because the resonant frequencies are the only significant contributors to fatigue stress, the first 3 resonant frequencies of this sine scan test were l !
- examined and the transmissibilities were determined from Reference 1. The j total response cycles to which the HCU test assembly was subjected witnin + {
5% of the resonant frequencies were then calculated. The total number oT l
- scans performed in testing from 5Hz to 100Hz during a 90 minute sine scan !
j test was first calculated using: }
(1) w f*w2 g
)' where, w = initial frequency (5 Hz) '
w 0 = final frequency (100 Hz) !
At a scan rate of 2 octaves per minute, t = 129.66 seconds.
Therefore, in 90 minutes there were:
90 x 60 = 41.75 = 41 scans completed
, 129.66 !
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The number of response cycles within + 5% of the first resonant frequency of the HCU at 17 Hz was determined next. As determined from the resonance search (Reference 1), the HCU exhibits a transmissibility of 5 at the hanger location at 17 Hz. There fore, a 0.75 g input results in a response acceleration of 3.759 at the hanger location. The total number of response cycles the HCU test assembly was subjected to at 17Hz were first calculated by differentiating equation (1) at 2 cetaves per minute and solving for dt.
The total number of response cycles were then obtained by integrating dt between w o and wf . The total number of response cycles equals:
30 x (wf - w*) (Reference 3)
Tn2 where, wf = w + SYw = 17 + (.05 x 17) = 17.85 wg = w - 5tw = 17 - (.05 x 17) = 16.15 Therefore, the total number of response cycles for 41 scans equals:
41 x 30 (17.85 - 16.15) = 3016 response cycles in2 .
The total number of response cycles were then converted to equivalent stress cycles by normalizing the TRS acceleration to the 59 peak of 17Hz in the worst RBS upset condition RRS (i.e., the highest required acceleration from
, the upset condition RRS of any of the three attachment points) and using the conservative average exponent of 2.5 as previously described. Therefore, the number of equivalent stress cycles imposed on the test HCU at 17Hz equals:
I.75 3
2.5 x 3016 = 1469 equivalent stress cycles 5 j The number of equivalent stress cycles at other resonant frequencies identified in the qualification report (Reference 1) were calculated in a l similar manner to provide a total of 8000 equivalent stress cycles, j
EQUIVALENT STRESS CYCLES INDUCED BY RMF TESTING t The number of equivalent stress cycles inposed on the HCU test assembly as a result of the SRV aging RMF testing in the side-to-side orientation was detemined next. From the 3 minute 40 second RMF testing, 30 seconds were 4
subtracted to al tow for the faulted condition loads (SSE, SRV and LOCA loads). The stress cycles from the remaining 3 minute 10 seconds (190
'econds) of RMF testing were normalized to the RBS upset condition RRS (OBE and SRV loading).
From a previous design calculation (Reference 4), a typical 30 second RMF test yields 200 equivalent stress cycles at the maximum required response level of a cceponent. The basis of this calculation is as follows:
The available test table time-history motions from a nunber of test labs were analyzed to detemine the number of stress cycles + at are expected in the response of a component from a 30 second durati L"t in which the Page 5 of 11 l
f l TRS envelopes an RRS. The shaker table input acceleration time-histories, i monitored by the control accelerometers, were applied to several
- single-degree-of-freedom (SDOF) oscillators ranging from SHz to 100Hz, one 1 at a thre. The number of stress cycles were then calculated by nonnalizing 1 the cycles in the alternating displacement response of an oscillator to the
- maximum value of its response. These normalized stress cycles at the TRS
! level were then converted into equivalent stress cycles at the corresponding
- response levels that were required to be enveloped during the test. This j analysis concluded that from a 30 second RMF test, 200 stress cycles can be expected in the response of SDOF oscillators having a frequency greater than i 25Hz. For oscillators with a natural frequency less than 25Hz, the
- equivalent stress cycles were slightly lower. However, the number of j equivalent response cycles also depends on the frequency content of the
! input motion. RMF testing which simulates hydrodynamic loads has a i relatively high frequency content. It is noted that the first resonance of 1 the HCU is 17Hz, with successive resonances of 25llz and greater. There fore ,
! it has been determined that the results of this analysis are applicable to i
the acceleration responses of the HCU t?st assembly considering that the ratio of the TRS and RBS upset condition RRS accelerations at 17Hz is much
! larger than that ratio used below in determining the equivalent stress
] cycles induced in the HCU test assembly at all resonant frequencies. As a
The HCUs at RBS are attached to the floor, a middle and an upper support
, point on the multifunction supporting structure. The minimum ratio of
- of the three attachment points is 2.9. This is the lowest of all the ratios
! obtained by examining the magnitude of the SRV TRS and the RBS design upset I condition RRS at all three attachment points for all the resonant
]
frequencies obtained from the qualification test report (Reference 1).
4 Therefore, the equivalent stress cy j by the RMF testing were 1.265 X (2.9)Qs at the18,100 (i.e., RBS upset condition equivalent stressinduced
! cycles). Thus, the total number of equivalent stress cycles induced from the dynamic testing successfully completed prior to the failure of the nitrogen cylinder hanger are (8,000 + 18,100) or, 26.100 equivalent stress cycles nonnalized to the RBS design upset condition RRS.
RBS DESIGN REQUIREMENTS I The RBS required stress cycles for equipment in containment are 5,200 due to j SRV actuations and 100 due to upset condition loads (OBE and SRV loads) or, i conservatively, S 300 equivalent stress cycles at the RBS design upset condition RRS for a 40 year life. The basis of 5200 cycles is provided in a calculation (Reference 4) which examir.ed the hydrodynamic event acceleration time-histories (ATH) from several locations within the reactor building.
The ATH selected were those that generated the most tevere amplified response spectra, both in magnitude and frequency content. The calculation of equivalent stress cycles (Reference 4) is based on the relative response of single degree of freedom (SDOF) uscillators and assumes the stress level is proportional to the SDOF oscillator's relative displacement. The result of the required 5200 stress cycles is based on the maximum envelope of the accelerations caused by 1, 2, 7 and 16 SRVs actuating.
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. l This implies that the equivalent stress cycles induced from the 3 minute, 10 second duration side-to-side orientation dynamic testing were approximately five times the RBS design required stress cycles. The margins in the front-to-back and vertical orientation are significantly higher, since testing in this orientation was completed for a full 15 minutes without failure.
It is noted that the above conclusion can also be reached in a different manner. As previously stated, the minimum ratio of accelerations between the TRS for the 3 minute 40 second test that preceded the nitrogen cylinder hanger failure and the RBS upset condition RRS at any of the three ,
attachment points for any HCU resonant frequency is 2.9. Using the previously described equivalence concept, the 190 second upset condition test duration is nonnalized to a test duration that corresponds to the RBS r upset condition RRS levels. Thus, the HCU was essentially tested in the side-to-side orienta RMF testing to an equivalent RBS upset level duration of 190 (2.9)Qn seconds or 45 minutes 21 seconds. The equivalent '
duration from the 90 minute, 0.759 input vibration aging tests normalized to i the RBS upset condition RRS level can also be calculated and added to this !
equivalent test dura tion. The total test duration required in order to i bound RBS for both SRV and upset conditions is less than 13 minutes (see '
Table 1) (Reference 4). Therefore, a similar margin of safety as calculated above would result for a full 40 years of qualified life.
From the evaluation summarized above it can be concluded that the test HCU l was subject to vibration fatigue far in excess of the seismic / dynamic design l environment, including SRV, upset, and faulted condition events that are i postulated to occur at RBS over the 40 year life. In addition, the HCU was !
demonstrated to be functional during and after the test conducted by GE. ;
Further, there have been much fewer SRV actuations at RBS to date than the j original estimation (200 at the TRS) used in detemining the implementation schedule. There fore , fatigue failure of the HCU nitrogen cylinder hanger ;
supports at RBS is not expected to occur. Using the methods described in ;
IEEE 344-1987 and Regulatory Guide 1.100, Revision 2 the unmodified HCUs i have been shown to be qualified at RBS in accordance with the requirements !
of IEEE 344-1975 Regulatory Guide 1.100 and NRC letter on hydrodynamic [
loads dated July 30, 1982 (References 5, 6 and 7, respectively). F NO $!GNIFICAV HAZARDS CONSIDERATIONS: l In accordance with the requirenents of 10CFR50.92, the following discussions are provided in support of the determination that no significant hazards are created or increased by the changes proposed in this amendment request. :
- 1. No significant increase in the probability or the consequences of an accident previously evaluated results from this request because:
There is nc, change to the original design configuration or operation af the HCUs, The proposed change allows continued operation of the i HCUs without further modifications for their qualified life of 40 [
years. The modifications currently required are based on f qualification testing results applicable to generic plant design I which have been shown to be overly conservative for RBS. [
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Further analysis performed by GSU shows that the installed HCOs continue to be qualified for application at RBS. The analysis examined the actual stress cycles imposed on the HCU test assembly i nitrogen cylinder support hanger prior to its fatigue failure during the dynamic qualification test.
Resonant frequencies were examined and the test accelerations imposed on the HCU test assembly were
- response spectrum (RRS). These results were compared to the RBS specific fatigue stress cycle requirements for typical structural materials provided in the ASME Code.
Determining the number of equivalent stress cycles is based on 4 Miner's theory of cumulative fatigue damage which is a standard i industry practice and is recommended in IEEE 344-1987 and the ASME Code. The results of this analysis demonstrate that the original qualification testing was conducted to acceleration levels that far exceeded the RBS design requirements. The testing that was conducted prior to the fatigue failure of the nitrogen cylinder hanger envelop the RBS design stress cycles when norfralized to the RBS design upset condition (OBE and SRV loading) RRS. Therefore, no fatigue failure of the HCU nitrogen cylinder hanger supports is expected to occur and the unmodified HCUs are qualified at RBS in accordance with the requirements of IEEE 344-1975 and Regulatory Guide 1.100. As a result, there is no significant increase in the probability or the consequences of any accident previously evaluated as a result of this proposed change.
- 2. This request would not create the possibility of a new or different kind of accident from any accident previously evaluated because:
The original qualified life of 4.4 years was based on the successful testing at the test response spectrum (TRS) performed prior to the fatigue failure of the nitrogen cylinder hanger. This test duration represented 200 SRV actuations (based on 1800 estimated for 40 year life) in addition to three upset (OBE and SRV loading) and one faulted condition (SSE, SRV and LOCA loading) events occurring at the TRS. There have been much fewer SRV actuations at RBS to date than the original estimation of 200 used in detennining the 4.4 year qualification. Additionally, these SRV actuations were not at the TRS level.
An examination of the testing conducted on the HCU prior to the hanger failure consisted of: (1) 90 minutes of vibration aging at 0.759 input (one in each orthogonal axis), (2) 15 minutes random, multifrequency (RMF) testing, biaxial excitation in the front-to-back and vertical directions, and (3) 3 minutes 40 seconds RMF testing, biaxial excitation in the side-to-side and vertical directions. The successful 15 minutes of RMF SRV aging testing in the front-to-back and vertical orientation of the unmodified HCU adequately envelop the design durations, magnitudes and faulted condition loads of RBS for those directions.
A calculation was made to deternine the equivalent stress cycles imposed on the HCU test assembly for the side-to-side orientation Page 8 of 11
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at all the resonant frequencies ia * ,.?inity of the nitrogen cylinder hanger prior to i +
ve failure at 3 minutes 40 ;
seconds of test (3) above. A w ie average expcaent of 2.5 '
(reference IEEE 344-1987) e. t M *, calculate the equivalence between the stress cycles induer d the TRS and the required !
design stress cycles, noting that excessive margins exists between !
the TRS and the RES upset condition RRS. ;
The 90 minute vibration aging test performed during the dynamic test was normalized to the RBS upset condition RRS using the !
methods described in IEEE 344-1987, resulting in 8000 equivalent '
stress cycles. From the random, multifrequency test (using the 3 minutes 40 seconds to account for testing in all three orthogonal !
dit ections ) , 30 seconds was subtracted to account for the faulted ,
conditionloads(SSE,SRVandLOCAloads). The remaining 3 minutes !
10 seconds were utilized to determine the equivalent stress cycles :
induceo @ r% g tha RMF SRV aging testing normalized to the RBS !
design upset condition (OBE and SRV loads) RRS. This was ;
calculited as follows:
Pet
- previous applicable RBS design calculations, a typical 30 [
- econds RMF test yields 200 stress cycles. Therefore, 3 minutes 10 l seconds (190 seconds) of testing yields 1265 cycles at the TRS. >
When these stress cycles are normalized to the RBS design upset condition RRS using the methods described in IEEE 344-1987, they ,
produce 18,100 equivalent stress cycles. From previous design calculations, the RBS design stress cycles for equipment inside I
':ontainment are 5,200 for SRV actuations and 100 for upset :
conditions for a 40 yeer life. This equates to S,300 equivalent i stress cycles at the RBS design upset condition RRS. The cumulative stress cycles imposed on the HCU test assembly at the ,
RBS design upset condition RkS as a result of testing conducted I prior to fatigue failure of the hanger equals (8,000 + 18,100) or, f 26.100 equivalent stress cycles compared to the RBS design "
requirement of 5,300 stress cycles. !
t It is clear that the testing completed prior to the nitrogen {
cyclinder hanger failure subjected the HCV test assembly to ;
equivalent stress cycles significantly higher than those postulated !
to occur for all the seismic and dynamic events during the 40 year !
life of RBS. Therefore, no fatigue failure of the HCU nitrogen !
cylinder hanger supports is expected to occur and the unmodified HCUs are qualified at RBS in accordance with requirements of IEEE 344-1975 and Regulatory Guide 1.100. As a resuls, no new or different kind of accidents arc created as a result of this proposed change.
- 3. This request would not involve a significant reduction in the margin of {
safety because: I The HCUs have been shown to be qualified to the RBS seismic / dynamic design requirements without the additional hardware modifications -
required by the current license condition. Analysis has shown that [
the qualification testing conducted prior to the fatigue failure of I Page 9 of 11 ,
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the nitrogen cylinder hanger demonstrates that the HCUs at RBS are ,
- qualified for 40 years with a safety margin of 3,9. The margins t l demonstrated by the successful testing conducted adequately .
3 envelope the seismic / dynamic design requirements described in IEEE !
l 344-1975 and Regulatory Guide 1.100. Therefore, the prcposed i i
change does not significantly reduce the margin of safety, t
i Based upon the above considerations the proposed change does not result in l
! a significant increase in the probability or the consequences of any l accident previously evaluated, does not create the possibility of a new or ;
4 different kind of accident than previously evaluated and does not result in '
i a significant reduction in the margin of safety. Therefore, GSU proposes that no significant hazards considerations are involved with approval of :
the proposed change, j
! REVISED LICENSE CONDITION-i f
) The requested revision is provided in Enclosure 1, i SCHEDULE FOR ATTAINING COMPLIANCE:
I River Bend Station is currently in compliance with the applicable license !
}. condition. To provide the operational flexibility required in obtaining !
the current RBS second refueling outage schedule. GSU requests this l proposed change be approved by January 31. 1989. This will allow advanced [
~
planning prior to the second refueling outage which is currently scheduled !
to begin March 15. 1989, i
] NOTIFICATION _OF STATE PERSONNEL:
) A copy of the amendment application has been provided to the State of !
! Louisiana. Department of Environmental Quality Nuclear Energy Division, 4
I j ENVIRONMENTAL IMPACT APPRAISAL:
[
i Gulf States Utilities Company (GSU) has reviewed the proposed license i 1 amendment against the criteria of 10CFR51.22 for environmental :
1 considerations, As shown above. the proposed changes do not involve a I significant hazards consideration, nor increase the types and amounts of i
effluents that may be released offsite, nor significantly increase individual or cumulative occupational radiation exposures, Based on the foregoing. GSU concludes that the proposed change meets the criteria given ,
in 10CTR51,22(c)(9) for a categorical exclusion from the requirement for an -
Environmental Impact Statement. ;
- I
)
REFERENCES:
) I
- 1. NEDC-30820. "Environmental Qualification Report (NUREG 0588 Category l
- 1) Book No, 512." January, 1985, l l
- i i 2. GSU Calculation G13.18.15.2*14 Revision 1. dated 11/2/88 "Dynamic !
Qualification of HCU for 40 Years", I
] '
i i l
} Page 10 of 11 {
i l<
- 3. Calculation 12210-EM-517.45.05-NM(C)-011, Revision 0, "Stress Cycles for Fatigue Evaluation", dated 9/30/83.
4 GSU Calculation 12210 EM-SQE-1924 Revision 2, "Reictor Building -
Fatigue Cycle Analysis", dated 5/28/86.
- 5. IEEE Standard 344-1975. "Recommended Practices for Seismic Qualification of Class IE Equioment for Nuclear Power Generating l Stations".
- 6. NRC Regulatory Guide 1.100, Revision 1, August 1977, "Seismic Qualification of Electrical Equipment for Nuclear Power Plants".
7 NRC letter dated July 30, 1982, Docket Nos. 50-458/459, A. Schwencer to W. J. Cahill, Jr., "Qualification of Safety Relat2d Equipment for Hydrodynamic Loads".
Page 11 of 11
i Taele 1 RBS REQUIREMENT FOR HCU SEISMIC / DYNAMIC QUALIFICATION LOAD CCNDITION NUMBER OF DURATION (TIME) CTC1.ES AT RBS RR5 AT RBS RR5 EVENTS (IACH AXIS) (EACH AXIS)
SRV 1800 10 MIN 18SEC 5200 l UPSET 5 150 SEC 100 car sav) .
FAULTED 1 30 SEC 100
<sst sav.un)
TOTAL NUMBER OF CYCLES REQUIRED FOR RBS SRV AND UPSET CONDITIONS ARE:
(5200 + 100)- 5300 CYCLES + FAULTED LOADS
a . !
Fiquro t HCU FLOOR l
(2% DAMPING) 1 RBS SRV RRS, AND SRV TRS I
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