ML17229A421
| ML17229A421 | |
| Person / Time | |
|---|---|
| Site: | Saint Lucie  |
| Issue date: | 07/22/1997 |
| From: | Stall J FLORIDA POWER & LIGHT CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| L-97-158, NUDOCS 9707290010 | |
| Download: ML17229A421 (16) | |
Text
CATEGORY DISTRIBUTION 1'EGULATO!OINFORMATION gEM (RIDE)
ACCESSION NBR:9707290010 DOC.DATE: 97/07/22 NOTARIZED: YES DOCKET FACIL:50-335 St. Lucie Plant, Unit 1, Florida Power & Light Co. 05000335 AI'i,H. NATE AUTHOR AFFiLIATION STALl'I .A. Florida Power & Light Co.
R" C f P. AP 'hE RECIPIENT AFFILIATION
=
Document Control Branch (Document Control Desk)
SUBJECT:
Application for amend to license DPR-67,incorporating=recent evaluation of postulated inadvertent opening of MSSV into current licensing basis.
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Florida Power & Light Company, 6501 South Ocean Drive. Jensen Beach, FL 34957 L-97-158 July 22, 1997 10 CFR 50.59 PPI 10 CFR 50.90 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D. C. 20555 Re: St. Lucie Unit 1 Docket No. 50-335 Proposed License Amendment Pursuant to 10 CFR 50.90, Florida Power & Light Company (FPL) requests to amend Facility Operating License DPR-67 to incorporate a recent evaluation of a postulated inadvertent opening'of a Main Steam Safety Valve (MSSV) into the current licensing basis for St.
Lucie Unit 1. An assessment of the potential consequences of this specific transient is not presently contained in the Updated Final Safety Analysis Report (UFSAR). This request for license amendment is required by 10 CFR 50.59(c).
Attachment 1 is the subject evaluation. Attachment 2 is the "Determination of No Significant Hazards Consideration."
requested that the proposed amendment, if approved, It is be issued by April 30, 1998.
The proposed amendment has been reviewed by the St. Lucie Facility Review Group and the Florida Power & Light Company Nuclear Review Board. In accordance with 10 CFR 50.91 (b)(1), a copy of the proposed amendment is being. forwarded to the State Designee for the State of Florida.
Please contact us if there are any questions about this submittal.
Very truly yours, Z. A. Stall Vice President St. Lucie Plant gobi ~
JAS/RLD llllllllllllllllllllllllllllllllllllllll'ttachments
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cc: Regional Administrator, Region II, USNRC.
Senior Resident Inspector, USNRC, St. Lucie Plant.
Mr. W.A. Passetti, Florida Department of Health and Rehabilitative Services.
'rr7072'F0010 970722 PDR<< ADQCK 05000335 P PDR
tE Lt. Lucie Unit 1 L-97-158 Docket No. 50-335 Page 2 Proposed License Amendment STATE OF FLORIDA )
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COUNTY OF ST. LUCIE )
Z. A. Stall being first duly sworn, deposes and says:
That he is Vice President, St. Lucie. Plant, for the Nuclear Division of Florida Power & Light Company, the Licensee herein; That he has executed the foregoing document; that the statements made in this document are true and correct to the best of his knowledge, information and belief, and that he is authorized to execute the document on behalf of said Licensee.
J. A. Stall STATE OF FLORIDA COUNTY OF S~ ~ L4LCL to E
Sworn and subscribed before me this ZZ+ day of , 1991 by J. A. Stall, who is personally known to me.
Signature of ry Public-State of Florida
,+ie~e~, Lsslie J. Whitwsll
~a) $ f
- s; MY COlWlSSION CC646163 May 12, 2001 EXPIAES
'~PjV',,i" B0%EO THRU TROY FAN NSURANCE, INC.
Name of Notary Public (Print, Type, or Stamp)
St. Llxcie Unit 1 Docket No. 50-335 Proposed License Amendment EVALUATION OF INADVERTENT OPENING OF A MAIN STEAM SAFETY VALVE
Bt. Lucie Unit 1 L-97-158 Docket No. 50-335 Attachment 1 Proposed License Amendment Page 1 of 6 A conservative assessment of the potential consequences associated with the inadvertent opening of a St. Lucie Unit 1 (PSL1) Main Steam Safety Valve (MSSV) was performed by Florida Power and Light Company (FPL) in conjunction with the NSSS vendor, Combustion Engineering (ABB/CE). The evaluation is based on a comparison of PSL1 transient analysis key input parameters for an Excess Load event to those of an explicit analysis performed to assess the postulated inadvertent opening of an MSSV reported in the St. Lucie Unit 2 (PSL2) Updated Final Safety Analysis Report (UFSAR). The impact of parameter differences between the two St. Lucie units was then evaluated and used to determine bounding values of two-hour site boundary radiation doses for comparison to 10 CFR 100 limits.
The same method was used to assess the minimum Shutdown Margin (SDM) that would be achieved during the transient at PSL1.
Changing the PSL1 UFSAR to include this evaluation requires prior NRC approval pursuant to 10 CFR 50.59, "Changes, Tests, and Experiments. "
The Chapter 15 accident analyses reported in the PSL1 UFSAR are based on the "Standard Format and Content of'afety Analysis Reports for Nuclear Power Plants," (USAEC) Guide l.70, Revision issued October, 2972. Postulated transients and accidents analyzed l,
for St. Lucie Unit 1 are listed in TABLE 15.1.1-1 of UFSAR section 15.1.1, CLASSIFICATION OF ACCIDENTS. The Class 1, EXCESS LOAD accident is described as, "Excessive load increase, including that resulting from a pressure regulator failure, or inadvertent opening of a relief or safety valve. " It should be noted that an excess load incident is defined as any rapid increase in steam generator steam flow ~~ than a steam line rupture (UFSAR-15.2.11.1).
The radiological analysis performed for the Excess Load event assessed the consequences of the inadvertent opening of a power operated atmospheric steam dump valve (ADV)." The results of this radiological analysis are contained in UFSAR section 15.2.11.2.3, and show that, for the set of assumptions contained in Table 15.2.11-5 (ADV open for 10 minutes), the dose to a person at the site boundary would be 0.0878 rem to the thyroid and 4.69 x 10 rem whole body. Other more severe steam demand scenarios were postulated to demonstrate that fuel design limits would not be violated.
An assessment of the inadvertent opening of an MSSV is not presently contained in the PSLl UFSAR, Chapter 15 safety analyses.
To support FPL's plans for future safety valve "in-place" set point verification in operational MODE 1, FPL determined that an
St. Lucie Unit 1 L-97-158 Docket No. 50-335 Attachment 1 Pr'oposed License Amendment Page 2 of 6 evaluation should be performed to conservatively estimate the consequences of a stuck open MSSV. Because the radiation doses determined by the evaluation demonstrate an increase in consequences beyond those of the radiological analysis reported for the existing Excess Load event .of record (inadvertent opening of an ADV), the postulated stuck open MSSV scenario represents an unreviewed safety question. In such cases, 10 CFR 50.59(c) requires that the licensee submit an application for amendment of the facility operating license.
The information presented in this section is based on FPL Safety Related Engineering Evaluation PSL-ENG-SENS-97-039, Revision 0, June 4, 1997, and attachments thereto. The Engineering Evaluation will be incorporated by reference into the PSL1 UFSAR pending NRC approval of this amendment application.
The evaluation includes a comparison of PSLl transient analysis key input parameters to those of an explicit analysis which was previously performed to assess the consequences of an inadvertent opening of an MSSV at PSL2, and is reported in PSL2 UFSAR Section 15.1.3.1.1. The impact of differences identified between the two units was evaluated and used to adjust the PSL2 analysis results to obtain the two-hour site boundary doses and the minimum shutdown margin that would be expected for this event at PSL1.
initiated from Hot Zero Power (HZP) conditions, and causes the entire blowdown of one steam generator (SG) and partial blowdown of the other SG. The assumed operating parameters were selected to maximize the radioactivity release and loss of SDM. Credit was taken for the protective action of the SG Water Level-Low trip, automatic starting of one safety injection pump, operator action after 10 minutes to terminate auxiliary feed water flow, and operator action after 30 minutes to commence boration to cold shutdown conditions.
In the calculation of site boundary doses, it was conservatively assumed that the maximum SG inventory (corresponding to HZP conditions) and all radioactivity in both SGs, including primary to secondary leakage, is released to the environment. Technical Specification (TS) values for maximum allowed primary to secondary leakage, SG activity, and RCS activity concentrations were used in the analysis.
For reactivity considerations, conservative assumptions were made that include: (a) a minimum Control Element Assembly (CEA) worth of
-4000 pcm available for shutdown at the time of reactor trip; (b)
St. Lucie Unit 1 II-97-158 Docket No. 50-335 Attachment 1 Proposed License Amendment Page 3 of 6 a maximum core inlet temperature for HZP conditions to maximize the total heat transferred from primary to secondary, and thereby maximize the total steam release through the stuck open MSSV; (c) the reactivity worth of boron injected by the safety injection system is -1.0 %Dp per 95 ppm, and (d) one of two available high pressure safety injection pumps fails.
Relative to radiological release and loss of Shutdown Margin (SDM),
the PSL2 analysis represents the worst case Anticipated Operational Occurrence (AOO) in the group of transients evaluated for increased heat removal by the secondary system. The two-hour site boundary doses are 2 Rem Thyroid (DEQ I-131) and 10 mrem Whole Body (DEQ Xe-133). The maximum post-trip reactivity is -1.2 Mp using a Moderator Temperature Coefficient (MTC) of -27 pcm/'F (original analysis), and -0.8 Mp using an MTC of -30 pcm/'F (current TS limit for negative MTC at rated thermal power).
Table 2 (Page 6 of 6 in this attachment) lists the key input parameters used in the PSL2 analysis.
The St. Lucie Unit 1 key parameters and references used in the evaluation are listed in Table 2 and can be easily compared to those used in the PSL2 analysis of an inadvertent opening of an MSSV. The PSL1 operating parameters consist of TS limiting values and initial conditions used in similar HZP events reported in the PSL1 UFSAR.
Like-for-like parameter values between the two PSL units are not further discussed except to note that, for a given set of secondary conditions, the MSSV orifice area of 16 in will provide the same rate of SG blowdown for both units.
For the small differences in (1'F) and combined (8 psi),
impact is not significant it was determined that and would not change the the conclusion reached in the evaluation. In addition, the difference in specifications involving will not affect the consequences of the transient, e.g., 1 gpm leakage to one SG or 1 gpm leakage split between the two SGs results in the same amount of total radioactivity since inventory, of both SGs is released.
it is assumed that the 1
Assessment af Site Boundary Doses: Given the same maximum
'hat concentrations of DEQ-Iodine and Noble Gas, and primary to secondary leak rate, a comparison of the PSL1 to PSL2 total radioactivity release will be a function of the is blown to the atmosphere. Since the PSL2 analysis assumes a
Bt. Lucie Unit 1 L-97-158 Docket No. 50-335 Attachment 1 Proposed License Amendment Page 4 of 6 slightly higher value for SG fluid inventory, the doses determined in the PSL2 analysis will be greater than those resulting from this transient at PSL1. Similarly, the larger value used for the in the PSL2 calculation will yield higher site boundary doses. Based on these differences, the comparative evaluation demonstrates that the PSL2 calculation of site boundary doses is at least 304 higher than would be expected from the same transient at PSL1. Therefore, the conservative estimate for two-hour site boundary doses 'resulting from an inadvertent opening of an MSSV at PSL1 is c 2 Rem Thyroid (DEQ I-131), and s 10 mrem Whole Body (DEQ Xe-133).
Assessment of Post-Trip Peak Reactivity: As a result of the comparative evaluation, the PSL2 post-trip peak reactivity (minimum SDM) was adjusted to provide a conservative prediction for PSL1 based on the following key parameter differences.
s (a) The difference between the PSL1 and the value used in the PSL2 analysis will directly change the PSL2 calculated value of post-trip peak reactivity (reduce the SDM) by 400 pcm.
(b) As described in Note (4) of Table 2, a change in the value of MTC from -27 pcm/'F to -30 pcm/'F resulted in a 400 pcm change in the calculated value of PSL2 post-trip peak reactivity. Based on this information, it was determined conservatively that the 1 pcm/'F difference between the PSLl and PSL2 HXg shown in Table 2 would likewise change the PSL2 post-trip peak reactivity (reduce the SDM) by no more than 200 pcm.
(c) The analysis of record for PSL2 shows that an Inverse Boron Worth (IBW) of 95 ppm/4hp results in a negative reactivity insertion of approximately 700 pcm after 30 minutes into the transient. The value of listed in Table 2 for PSL1 is slightly less conservative than the PSL2 value. It was determined that this difference would change the PSL2 calculated value of post-trip peak reactivity (reduce the SDM) by no more than 70 pcm.
The post-trip reactivity calculated in the PSL2 analysis (-1200 pcm corresponding to MTC -27 pcm/'F) was adjusted to reduce the SDM by 670 pcm to account for the total effect of the PSLl reactivity differences. The conservative estimate of post-trip 'eak reactivity for this transient at PSL1 at the time the operator begins to borate the system to cold shutdown conditions is -530 pcm. Therefore, criticality would not occur as a result of an inadvertent opening of an MSSV at PSL1.
St. Lucie Unit 1 L-97 158 Docket No. 50-335 Attachment 1 Proposed License Amendment 0
Page 5 of 6 The comparative evaluation demonstrates that the radiological consequences from an inadvertent opening of an MSSV at PSL1 is conservatively bounded by the results of the explicit analysis performed for that event at PSL2. As shown in Table 1, the potential two-hour site boundary doses predicted for St. Lucie Unit 1 are higher than those reported for the Excess Load event in the PSLl UFSAR (inadvertent opening of an ADV), but the doses remain a small fraction of 10 CFR 100 limits.
TABLE 1. TWO-HOUR SITE BOUNDARY DOSES (PSL1)
Event / Subject Thyroid Dose Whole Body (REM) Dose (REM)
Inadvertent Opening of ADV 0.0878 0.0000469 Stuck Open MSSV 0.01 10 CFR 100 Limits 300 25 The minimum SDM that would be achieved during this transient at PSL1 demonstrates that criticality would not occur following the reactor trip from HZP. In addition, it should be noted that the design of the Main Steam Isolation Valves at PSL1 includes a reverse-flow check valve. To maximize conservative results in the comparative evaluation, credit was not taken for this design feature.
St. Lucie Unit 1 L-97-158 Docket No. 50-335 Attachment 1 Proposed License Amendment Page 6 of 6 PARAMETER PSL1 REFERENCE4 PSL1 VALUE PSL2 VALUE*
RPS Trip Setpoint, SG Water Level-Low TS Table 2.2-1 19.5 % (note 1) 19.5 % (note 1)
Available SDM at time of trip TS 3.1.1.1 3600 pcm 4000 pcm (note 2)
Initial Power UFSAR Table 15.2.11-3 1MWt 1MWt Initial Inlet Temperature UFSAR Table 15.2.11-3 534 'F (note 3) 535 F Initial Pressurizer Prcssure UFSAR Table 15.2.11-3 2178 psia (note 3) 2170 psia Initial Core Mass Flow UFSAR Table 15.2.11-3 137 E6 ibm/hr 137 E6 ibm/hr TS 3.1.1.4 (COLR 2.1) -28 pcm/'F -27 pcm/'F (note 4)
Doppler Multiplier UFSAR Table 15.2.11-3 0.85 0.85 Primary to Secondary Leak Rate TS 3.4.6.2 1 gpm all SGs 1 gpm all SGs, 720 gpd any one SG MSSV Orifice Area TS 3.7.1.1, Table 4.7-1 16 16 in~
in'.0 RCS Maximum Allowable DEQ I-131 Concentration TS 3.4.8.a pCi/gram 1.0 pCi/gram RCS Maximum Allowable Concentration of Noble Gases TS 3.4.8.b 100/E pCi/gram 100/E pCi/gram SG Maximum Allowable DEQ I-131 Concentration TS 3.7.1.4 0.1 pCi/gram 0.1 pCi/gram SG Fluid Mass (Total both SGs) UFSAR Table 15.4.6-1 446,204 ibm 448,000 ibm Atmospheric Dispersion (note 5) (note 5)
Coefficien, 0-2 hours at EAB UFSAR Table 15.2.11-5 1.2 E-4 1.6 E-4 sec/m'.47 sec/m'.47 Breathing Rate UFSAR Table 15.2.11-5 E-4 m'/sec E-4 m'/sec Dose Conversion Factor UFSAR Table 15.4.4-3 1.48 E6 Rcm/Ci 1.48 E6 Rem/Ci Maximum Inverse Boron Worth UFSAR Table 15.2.11-3 100 ppm per%hp 95 ppm per %hp
~ PSL1 UFSAR through Amendmcnt 15 (1/97), TS through Amcndmcnt 151(5/97), COLR Revision 0. The PSL2 event is described in UFSAR Section 15.1.3.1.1. Parameter values are documented in UFSAR Section 15.1.3.1.1.2, UFSAR Tables 15.1.3.2, 15.1.3.3, and 15.0-19 (PSL2 UFSAR through Amendment 10, 7/96), and/or the analysis of record.
(1) Minimum allowablevaluepermittcdby TS. Results in longer time toreactor trip and greater steamrclease.
(2) PSL2 required SDM per TS 3.1.1.1 is 5000 pcm. The analysis of record conscrvativcly used a minimum CEA worth for HZP of 4000 pcm (available for shutdown at time of reactor trip).
(3) PSL1 UFSAR Table 15.2.11-3 lists nominal values of 532 'F for inlet temperature and 2200 psia for pressurizer prcssure. UFSAR Section 15.1.6.3 lists unccrtaintics of+2 'F and -22 psia, rcspectivcly, for these parameters.
(4) Original PSL2 analysis used MTC -27 pcm/'F, which yields a post-trip peak reactivity of -1200 pcm. UFSAR Section 15.1.3.1.1.3 also reports results for MTC -30 pcm/'F, which yields a post-trip peak reactivity of -800 pcm. Original PSL2 analysis MTC is used in thc peak reactivity comparative evaluation because that MTC is closer to the PSL1 value.
(5) PSL1 methods from AEC Safety Guide 4. PSL2 methods from USNRC Regulatory Guide 1.145.
. ~
St. Lucie Unit 1 Docket No. 50-335 Proposed License Amendment DETERMINATION OF NO SIGNIFICANT HAZARDS CONSIDERATION
St. Eucie Unit 1 L-97-158 Docket No. 50-335 Attachment 2 Proposed License Amendment Page 1 of 2 DETERMZNATZON OF NO SZGNZFZCANT HAZARDS CONSZDERATZON Description of'mendment request: The proposed amendment will incorporate a recent evaluation of a postulated inadvertent opening of a Main Steam Safety Valve (MSSV) into the current licensing basis for St. Lucie Unit 1 (PSL1). An assessment of the potential consequences of this specific transient is not presently contained in the Updated Final Safety Analysis Report (UFSAR), and the proposed license amendment is required by 10 CFR 50.59(c).
Pursuant to 10CFR50.92, a determination may be made that a proposed license amendment involves no significant hazards consideration operation of the facility in accordance with the proposed amendment if would not: (1) involve a significant increase in the probability or consequences of an accident previously evaluated; or (2) create the possibility of a new or different kind of accident from any accident previously evaluated; or (3) involve a significant reduction in a margin of safety. Each standard is discussed as follows:
(1) Operation of the facility in accordance with the proposed amendment would not involve a significant increase in the probability or consequences of an accident previously evaluated.
The Unit 1 UFSAR includes analyses for excess load events; however, a stuck open MSSV is not specifically evaluated in the UFSAR. This proposed amendment will add an evaluation of an inadvertent opening of an MSSV to the licensing basis of the plant. The probability of occurrence of an excess load event is not increased by this amendment since the frequency of initiating events.has not changed and there is no change to the plant or plant operation as a result of this amendment. Thus, there is no significant increase in the probability of any accident previously analyzed.
The radiological consequences of an excess load event other than steam line ruptures are discussed in UFSAR Section 15.2.11.2.3, and are. based on the inadvertent opening of an Atmospheric Steam Dump Valve (ADV). This proposed amendment revises the radiological consequences of the UFSAR excess load event to incorporate the results of a recent evaluation of an inadvertent opening of an MSSV. The consequences of the postulated MSSV scenario are greater than those of an inadvertent opening of an ADV, but the predicted two hour site boundary doses remain a small fraction of 10 CFR 100 limits. In addition, the Unit 1 results are bounded by the St.
Lucie Unit 2 analysis results which are reported in Section 15.1.3.1.1.3 of the Unit 2 UFSAR. Therefore, operation of the
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l.
'St. Lucie:Unit 1 L-97-158 Docket No. 50-335 Attachment 2 Proposed License Amendment Page 2 of 2 facility in accordance with the proposed amendment will not involve a significant increase in the consequences of an accident previously evaluated.
(2) Operation of the facility in accordance with the proposed amendment would not create the possibility of a new or different kind of accident from any accident previously evaluated.
The proposed amendment will add an evaluation of an inadvertent opening of an MSSV to the licensing basis of the plant. The evaluation addresses an anticipated operational occurrence (AOO) and is classified as an Excess Load event under the PSL1 accident classification criteria. Although an analysis of this specific transient is not currently provided in the UFSAR, analyses of Excess Load .events other than steam line ruptures are reported in UFSAR Section 15.2.11. The amendment does not change plant design or operation and does not introduce new failure modes or system interactions. Thus, operation of the facility with the proposed amendment will not create the possibility of a new or different kind of accident from any accident previously evaluated.
(3) Operation of the facility in accordance with the proposed amendment would not involve a significant reduction in a margin of safety.
The proposed license amendment adds an engineering evaluation to the licensing basis of the plant to address the consequences of a postulated stuck open MSSV. A change is not being made to plant design or operation. A change is not being made to any Technical Specification Limiting Condition, for Operation, Action, or Surveillance Requirement. The evaluation demonstrates that, post-trip, the reactor would remain subcritical throughout the transient, and that the radiological consequences of a stuck open MSSV are a small fraction of 10 CFR 100 limits. Therefore, operation of the facility in accordance 'with the proposed amendment would not involve a significant reduction in a margin of safety.
Based on the discussion presented above, FPL has concluded that this proposed license amendment involves no significant hazards consideration.