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- october 22, 1997 MDOBMEUI TD:
John A. Grobe. Acting Director Division of Reactor Safety, RI!!
Robert A. Capra Project Director ggg Flpt:
Project Directorate III-2 Division of Reactor Projects !!!/IV office of Nuclear Reactor Regulation SURJECT:
REGION III TASK INTERFACE AGREEMENT: CONTAINMENT SPRAY ADDITIVE SYSTDI CONFORMANCE WITH DESIGN BASIS AND TECHNICAL.
SPECIFICATIONS (TAC N05. M9622J, M96224, M96225, AND M96226)
(TIA NO. AITS 0311)
By memorandum dated September 12, 1996, Region !!! (RIII), Division of Reactor Projects and Division of Reactor Safety, submitted a Task Interface Agreement (TIA) to the Office of Nuclear Reactor Regulation (NRR), Division of Reactor Projects III/IV, requesting that NRR perfora a review of the spray additive systems (SAS) at Byron, Braidwood, and Zion Stations to determine if Commonwealth Edison Company (Comed) was complying with the plant-specific design basis and Technical Specifications (TS) and whether appropriate Environmental Qualification requirements have been applied to equipment inside containment.
The concerns arose when the Braidwood SAS failed its TS-required surveillance on March 21, 1996. The failure was caused by inadequate test procedures that did not correct the water density when seasuring system flow rates. Upon further review, RIII noted that Byron and Braidwood Stations, which are similar in design, use different test conditions to conduct the TS surveillance. The test differences will result in different settings of the SAS throttle valve, which will affect the rate of NaOH addition during containment spray system (CSS) and SAS operation.
There were follow-up discussions to clarify RI!!'s concerns and the level of review to be provided by NRR. In accordance with those discussions, the Materials and Chemical Engineering Branch (EMCB) in NRR's Division of Engineering reviewed the available design bases and performed confirmatory analyses to evaluate the safety significance of the issue.
To evaluate the safety significance, EMCB ran bounding cases and cases based on the surveillance test results. All of these cases produced acceptable results. EMCB also demonstrated that a wide-range of SAS flow rates is acceptable - the ratto of NaOH flow to spray flow can vary by up to a factor I
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of three and still produce pH levels sufficient to retain todine in the sump water and prevent long-ters custic corrosion of equipment inside containment.
Staca sump and long-tera spray pH are relatively insensitive to flow from the SAS, there is low safety significance to variations in the test conditions and the flow rates observed.
To answer the first three questions of the TIA, as stated, would have required a detailed review of Coned's design basis. These questions relate to the exact test conditions needed to verify system operability in accordance with the plant-specific TS. Based on EMCB's analysis, which demonstrates a low safety significance, NRR and RIII agreed that the detailed engineering review of CoeEd's design basis is not warranted and the review provided by NRR, as summarized below, is sufficient to address RI!! concerns.
RIII's questions and a summary of MRR's responses are as follows:
1.
At Byron, the current surveillance methodology apparently asintains spray pH 8.5-10.5 and meets the 55-60 spe requirement with educator active fics.
not throttled (about 150-155 gpe) and the spray additive tank (SAT) simulated full. If an initiation of CS [ containment spray] occurred, native flow would be lower (about 130-135 gpe) due to reduced CS pump dp which would siso reduce spray additive flow, apparently to less than 55 ppe. Does this conform with the TS and design basis for the facility?
What is the intent of the FSAR [ Final Safety Analysis Report) time band of 32-47 minutes to complete adding the Ma0HT The staff's review of the FSAR and TS did not provide sufficient information to determine the exact test conditions that were required by Byron's licensing basis when the test was conducted. However, EHCB's analysis confirms that the test conditions used at Byron, and the resultant SAS throttle valve settings, provide the required sump pH as specified in,the TS bases.
Note that Comed has completed a design basis reconstitution on the CSS and SAS to clarify the requirements. This reco'nstttution determined the SAS flow should be 55-60 gpm (the TS value) with the eductor flow equal to 130-135 gpa (the FSAR value) when the SAT is full (the b value). The reconstitution developed a system description and changes to the FSAR to provide a more complete description and to remove incorrect and/or conflicting information.
The intent of the FSAR time band of 32-47 minutes to complete adding NaOH only applies to the case of a large break loss-of-coolant accident (LOCA) concurrent with a single failure of a spray additive valve to open. The operators inject NaOH for an additional 15 minutes in order to ensure the water in the sump fluid will remain basic.
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At Erst 6 rood, the servelliance is done with SAT 1evel simulated to be mid-tank and educator active flav at about 135 spe. If an initiation occurred with tank level at 90 percent (TS require the SAT level to be 16-90 percent full), spray additive flow would potentially be higher than 60 spe with a corresponding effect en pH. Does this conform to TS and the design basis for the facility?
The staff's rsview of the FSAR and TS did not provide sufficient information to deterstne the exact test conditions that were required by Braidwood's 11cer: sng basis when the test was conducted. The test appears consistent with the FSAR de!cription of the system since the FSAR states SAS flow rate remains the same (55-60 gps) as the SAT drains.
However, C:: sed's design basis reconstitution of the CSS and SAS determined that the FSAR description was incorrect in that flow through the SAS varies throughout the event due to changes in CS flow and SAT level. The design basis reconstitution determined the SAS flow should be 55-60 gps (the TS value) with the eductor flow equal to 130-135 gpm (the FSAR value) when the SAT is full (the TS value). The reconstitution developed a systes description and changes to the FSAR to provide a more complete description and to remove incorrect and/or conflicting information.
While the staff did not perform an in-depth analysis of the as-left' condition, EMCB's analysis indicates that the test conditions used at Braidwood, and the resultant SAS throttle valve settings, should provide the required sump pH as specified in the TS bases. The licensee should have an analysis of the actual as-left condition to verify an acceptable pH range.
3.
At Byron /Braikood, spray additiva flow apparently cannot be maintained at 55-60 gpe from a full SAT to empty. Each plant uses different educator active flow and simulates the SAT st a different level during survelliance testing. TS do not specify survelliance initial conditions.
At what conditions should the survelliance be performed at these stations?
The Byron /Braidwood design reconstitution concluded the following: spray additive system throttle valves should be set such that NaOH flow is 55-60 gpm (equivalent to 68-74 gpm primary water, which reads as 62-67 gpm on FI-C5015/16 due to density correction) with the SAT at high level and the educator motive loop flow equal to the values determined during pre-operational testing (about 130-135 gpm). The Byron and Braidwood procedures should be modified to reflect tne above test conditions before the next TS survelliance is conducted.
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At Elen, the C$$ and SAS for laelts I and 2 are designal such that the Wa0R flav amtst be adeguate te add the required amount of caustic to the sentainment sep prior to anptyisy of the W5T [rwfeeling water storage t ank). Elee enfatsins an Ma0Fi sencontration of about 40 vt.-% in the SAT (15 requits > 30 vt.-5). Accident analysis at Zion takes credit for only one C5 paap edecting caustic at 50 spe. During a LOCA, the RV5T could aapty in as little as 34 einetes (as stated in Zion's LWSAR, tine? Appendix 6, p.60-5). Will an adeneste amount of Ma0N be added in this In addittee, ConCd has no liceeslag, 75, er regulatory requirement to maintain a nitrogen blanket en the SKT st Zion. Es there a negative effect en the caustic solutten at Zion free being vented to the atmosphere testead of having a nitrogen blanket en the spray additive tankt Based on the staff's independent analyses, an adequate amount of NaOH is added with only one C5 pump educting caustic at 50 gpa at Zion.
The lack of a nitrogen blanket on the SAT may lead to a gradual acidification of the solution, which would reduce the solution's ability to perfom its design function. The staff believes there is sufficient margin to accommodate this effect and, therefore, the safety significance is low. In addition, the licensee has analyzed samples of the solution and determined the acidification to be minisal. Therefore, the staff should not seek to impose a requirement for a nitrogen blanket on the SAT at Zion. However, if the plant does not saintain a nitrogen blanket or take other actions to prevent acidification, the licensee should factor the acidification into the pH calculations.
5.
At all three sites, the effect on equipment Environmental Qualification (EQ) of high C5 pH (>10.5) needs to be assessed. Westinghouse concerns about this satter are documented in Attacheent 2.
Additionally, the use of Vantage 5 fuel necessitates a higher RV5T boren concentration (apparently, the previous mininue was 2,000 ppet the current TS band is 2,400-2,600ppe). The effect of this on spray and sump pH requires assessment.
Both Coned'g and the staff's evaluation predict significantly lower pH levels than the Westinghouse predictions. Nevertheless, the Byron /8raidwood design reconstitution does state that spray pH can briefly exceed 11.0 during the time between the CS switching suction to the containment sump and the SAT emptying. CosEd states there is no EQ concern due to the short duration of the high pH condittoa. Because the maximum pH is only slightly higher than that reported in the UFSAR (a pH of 11.5 vs.11.0 in the UFSAR), and the short duration of the higher pH (approximately 30 minutes), the effect on equipment should be minimum.
However, the licensee should confirm the effect on EQ (i.e., by reviewing the equipment qualification test reports).
J. Grobe 5-The staff's analysis concluded that 2,400-2,600 ppe in the RWST is acceptable. Additional details of the staff's assessment are included in the attachment.
Docket Hos. STN 50-454, STN 50-455, STN 50-456, STN 50-457, 50-295, 50-304
Attachment:
As stated cc w/att:
C. Hehl, RI J. Wiggins, RI J. Johnson, RIl J. Jaudon, RI!
T. Gwynn, RIV A. Howell, RIV l
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J. Grobe The staff's analysis concluded that 2,400-2,600 pra in the RWST is acceptable. Additional details of the staff's assessment are included in the attachment.
Docket Nos. STN 50-454 STN 50-455, 1
STN 50-456, STN 50-457, 50-295, 50-304
Attachment:
As stated cc w/att:
C. Hehl, RI J. Wiggins, RI J. Johnson, RI!
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STAFF RESPONSE TO THE TASK INTERFACE AGREEMENf REGARDING SPRAY ADDITIVE SYSTEMS AT THE BYRON. BRAIDWOOD AND ZION STATIONS
1.0 INTRODUCTION
On March 21, 1996, the Commonwealth Edison Company (Comed, the licensee) determined that, as a result of incorrect testing methodology, the settings for flow from the spray additive system (SAS) at the Byron and Braidwood Stations would result in SAS flows outside of the range specified in the Byron /Braidwood Technical Specifications (TS). By memorandum dated September 12, 1996 Region !!! (RI!!), Division of Reactor Projects and Division of l
Reactor Safety, submitted a Task Interface Agreenent (TIA) to the Office of j
Nuclear Reactor Regulation (NRR) Division of Reactor Projects III/IV.
In this TIA, RIII requested that NRR perform a review of the SAS at Byron, Braidwood, and Zion Stations to detemine if Comed was complying with the plant-specific TS.
Numerous conversations about the scope of tt.ls TIA were held between RIII and NRR. It was agreed that NRR would focus on the safety significance of the issue in lieu of performing a detailed review of Coned's design calculations.
Background information is provided in Section 2.
The staff's assessment and a discussion of the safety significance are provided in Section 3.
The staff's conclusions are provided in Section 4.
2.0 BACKGROUND
INFORMATION 2.1 Puroese of the Sorav Additive System The SAS at Byron, Braidwood, and Zion Stations are designed to operate u.
conjunction with the containment spray systems (CSS) during a postulated design basis loss-of-coolant accident (DBLOCA) in order to achieve the following safety 'related functions:
control of fission products released to the containment atmosphere; and control of pH of the inventory in the containment sump.
a During a postulated DBLOCA, it is crucial to contrsi the amount of fission products (and, in particular, radioactive iodine species) released to the containment atmosphere in order to ensure that the amount of fission products released to the outside environment is in compliance with the radioactive release limits specified in 10 CFR Part 100, " Reactor Site Criteria." For those licensees that credit a safety-related CSS for the reduction of radioactive iodine doses during a postulated DBLOCA, it is important from a safety standpoint to maintain the inventory in the containment sump at a caustic or basic pH (e.g., pH > 7.0 at 25'C; pH > 6.3 at 85'C). This is due ATTACHMENT l
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to the following series of reversible chemical reactions for elemental type lodine species:
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An analysis of the equations, according to Le Chatelier's Principle, shows l
that neutralizing the acidity (e.g., H' ions) produced by the reaction of aqueous iodine with water would tend to drive Reaction -(2) to the right, which would in turn promote solubility of gaseous einmental iodine into solution.
This is dene at Byron, Braidwood, and Zion by means of the SAS which inject concentratedsodiumhydroxide(NaOH)intothaCSS.
l An upper limit on sump pH is also identified for equipment environmental qualification (EQ) conce:ws. Long-term exposure to a high pH can lead to degradation of materials inside containment, including caustic cracking of stainless steel piping. An upper bound sump pH of 11 is typical. The Byron and Braidwood TS Bases specify an upper pH limit of 11 for the sump; hovever, the FSAR specifies an upper limit of 10.5.
2.2 Byron /Braidwood SAS Desions l
At the Byron and Braidwood Stations, the two trains of SAS inject into the CSS trains at the eductor in the eductor loop. The pressure drop across the eductor creates a siphoning effect which, upon opening of the SAS control 4
1 valve, promotes flow from the spray additive tank (SAT). At Byron and Braidwood, the SAS discharge into the CSS at a point downstream from the junction at which the CSS recirculation piping joins the CSS piping from the refueling water storage tank (RWST). This allows the SAS to be aligned with j
the CSS during a postulated DBLOCA even after the source of the CSS has been switched (realigned) to the containment sump.
4 2.3 Zion Station SAS Desians The design of the CSS and SAS at Zion is somewhat different from Byron and Braidwood Stations. Each Zion unit has three independent CSS trains which are i
aligned to the RWST, and three independent SAS trains. Each SAS train is coanected to the corresponding CSS train at the eductor motive loop. Thus, the SAS at Zion is actuated in the same manner as those at Byron and Braidwood Stations. However, at Zion the residual heat removal (RHR) system is used to provide containment spray flow after the RWST is empty. The CSS pumps and eductor loops are upstream of the CSS ties to the RHR system. Therefore, at Zion the SAS can only be acturted when the CSS is taking the suction from the RWST; no SAS injection is possible when the CSS is aligned to the containment sump.
l
2.4 Aceroertate Final Safety Analysis Reeert (FSAR) Chanters and TS l
The appropriate FSAR Chapters for the emergency safety features (ESF),
including the emergency core cooling system (ECCS), CSS, and SAS, are found in Chapter 6.0 (and, in particular. Sections 6.1, 6.2, 6.3 and 6.5 of the Chapter) of the corresponding Byron and Braidwood Stations and Zion FSARs. A summary of the accident analyses for large break DBLOCAs may be found in Chapter 15 of the corresponding FSARs.
Appendix 1 to this assessment provides the appropriate TS sections for the borated systems and the SASS at Byron and Braidwood Stations and Zion.
In summary, the 5-year surveillance test for the SASS at Byron and Braidwood Stations is in compliance with the TS surveillance requirements if the flow rate of test water "from the eductor test connections" is in the range of 68-74 gps. According to the Byron and Braidwood Stations TS, this flow rate range equates to a flow rate of 55-60 gpm for a 30 wt% NaOH solution. The purpose of the SAS surveillance test at Byron and Braidwood Stations is to ensure that a sufficient amount of NaOH will be added to the Byron and Braidwood Stations containment sumps in the event of a DBLOCA. This assures that the pH of the inventory in the containment sump will be in the target range of 8.5-11 (T$ 8.5-10.5 per the FSAR) during the postulated event.
It should be noted that the TS'for the Zion Station do not have a corresponding surveillance test for the Zion SAS.
The staff's evaluation also used information provided by Cr.mEd by letter dated November 13, 1996. This letter contained the results of an SAS design basis review / reconstitution effort at Byron and Braidwood Stations, and includes a system design description (SDD), a Nuclear Design Information Transmittal (NDIT), which transmits the surveillance test conditions, and a proposed Updated Final Safety Analysis Report (UFSAR) change and the corresponding 10 CFR 50.59 evaluation.
2.5 Staff Analysis of Safety Significance To address how safety significant the issues at the Byron, Braidwood, and Zion Stations were, the staff developed a computer code, which was written to simulate the pH profile of the containment sump during a postulated DBLOCA over a range of possible system parameters. The staff focused on the sump pH instead of the spray pH because the sump pH has a higher safety significance due to its affect on long-term iodine retention and material corrosion.
For the Byron and Braidwood Stations' simulations, the staff ran sets of chemistry and ECCS, CSS, and SAS input parameters for each of the following five single failure assumptions:
(1) failure of the A or B train low-headcommon mode failur totheBtrainsafetyequipment;(2)failureoftheAorBtrainSASinjection safety injection pump to start; (3) valve; (4) lure. failure of the B train containment spray pump to start; and (5) no active fai These failure assumptions are all mentioned or discussed in the Byron and Braidwood Stations FSAR, Chapter 6.0.
For the Zion simulations, the staff ran sets of input parameters for each of the following three failure l
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assumptions: (1) failure of both the B and C train CSS pumps to start (a double failure assumption with is consistent with the Zion accident analyses);
(2) failure of the C train CSS pump to start; and (3) no active failure. The assumed failure assumptions for the' Zion Station are consistent with the failure modes discussed in Chapter 6.G 4 Zion's FSAR.
The staff's computer code model was 4
- ved and verified by the Senior Chemical Engineer in the Materials se' ihemical Engineering Branch (EMCB) and benchmarked against the pH profile tosponse in Figure 68-1 of Appendix 6B to the Zion FSAR. The pH profiles resulting from the staff's computer code simulations of the containment sump response at the Zion Station were similar to the pH profile depicted in Figure 68-1 of the Zion FSAR. Maximum variation between the results of the staff's simulations of the pH response of the containment sump at the Zion Station and the pH profile in Figure 68-1 of the Zion FSAR was 10.6 pH units.
The computer code did not model the flow of water through the eductor motive loop since this loop does not provide input of water to the sump. The computer code modeled the reaction of the boric acid in the sump with caustic and treated the reaction as a simple titration of boric acid with NaOH. No equilibria were assumed to exist from polyborate complexes. Note that the computer model was used simply as a basis to confirm the pH range that would result in the containment sump during a postulated DBLOCA and was not used as a basis to establish whether or not Comed was in compliance with their, i
licensing bases or design bases for the plants. The results of the computer code runs for Byron and Braidwood Stations and Zion are sumarized in Tables i
1, 2, 3, and 4 of Appendix 2 to this assessment.
l
3.0 ASSESSMENT
The staff of EMCB was requested to address five series of questions. These questions are addressed in Subsections 3.1, 3.2, 3.3, 3.4, and 3.5.
3.1 At Byron, the current surveillance nethodolony apparently maintains spray pH 8.5-10.5 and meets the 55-60 spe requirement with eductor nativeflownotthrottled(about 150-155 gpe) and the spray additive tank (SAT) simulated full. If an initiation of CS [ containment spray) occurred, native flow would be lower (about 130-135 gpe) due to reduced C5 pump dp which would also reduce spray additive flow, apparently to less than 55 gpe. Does this conform with TS and the design basis for the facility? What is the intent of the FSAR time band of 32-47 minutes ta complete adding the Ms0HT 7
l At Byron, the test water flow rates for the surveillance test were initially less than the 68-74 gpm required by the TS, and it was not until the licensee had set the eductor motive loop throttle valve to the completely open position that the test water flow rates were brought into the range required by the TS.
Section 6.5 of the Byron and Braidwood Stations FSAR states that the design flow rate through the eductor motive loop is 130-135 gps. Setting the valve
position to the completely open position yieiced a flow rate through the eductor motive loop of 150-155 gpm (the higher flow rate is caused by the test conditions, which yleid a higher CS pump differential pressure because there is no flow through the spray header). Before the eductor motive loop flow was increased, SAS flow rate was approximately 42-46 gpe. The Byron and Braidwood Stations' design documents that were available when the tests were conducted are not clear under which conditions the SAS flow should be between 55-60 gpm.
For the situation at the Byron Station, the safety issue is: would a flow rate of 42 gpa from the SAT, as derived from the TS surveillance test flow rates, provide a sufficient amount of NaOH to keep the pH of the sump above neutral (e.g., a pH > 6.3 at 85'C; a pH > 7.0 at 25'C)? To assess the first concern, the staff ran the computer code using inputs that would conservatively minimize the pH values in the sump during the postulated DBLOCA. Table 1 in Appendix 2 provides the results of the staff's modeling of the pH in the containment sump during a postulated DBLOCA concurrent with each of the assumed single failure events. The staff's assessment indicates that the pH's in the containment sump will be sufficiently basic even for the low SAT flow rate (42 gpm) condition that occurred when the eductor motive flow was in the normal design range (130-135 gpm). Comed has informed the staff that the pH of the containment sump will remain above 7.0 even if the flow rates from the SAS are as low as 19.0 gpm. According to Comed's design reconstitution, this condition bounds the case where eductor motive loop flow is reduced and the SAT is at the Lo-2 level. The staff's independent analysis using an SAS flow rate of 19.0 gpm confirms the licensee's assertion.
Therefore, 42 gpm would not change the partition coefficient for elemental iodine and invalidate Comed's 10 CFR Part 100 todine release rate analysis for the Byron faellity. Therefore, Byron's test met the TS basis requirements for pri.
The intent of the UFSAR time band of 32-47 minutes to complete adding NaOH only applies to the case of a large break LOCA concurrent with a single failure of a spray additive valve to open. The context of the FSAR in this case (see p. 6.5-30 of the Byron /Braidwood FSAR) appears to be based on, a 30 wt% NaOH solution, a minimum allowable SAT level of ~79%, and an SAS flow rate of 60 gpm (1 train). At -32 minutes, the CSS trains are manually switched to the recirculation mode. The operators are' trained to close the spray additive valves in 47 minutes. The operators inject NaOH for an additional 15 minutes in order to ensure the water in the sump fluid will remain basic during the course of the event.
the surselliance is done with SAT level simulated to be At Braidwood, ductor native flow at about 135 ppe.
3.2 mid-tank and e If an initiation occurred with tank level at 90 percent (T5 require the SAT 1evel to be 78-90 percent full), spray additive flow would potentially be higher than 60 gpe with a corresponding effect on pH. Does this conform to T5 and the design basis for the facility?
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clear under which conditions the SAS flow should be 55-60 gpm. The Byron and Braidwood Stations UFSAR states that' flow remains from 55-60 gpm while the RWST is drained, which would imply that the above test is acceptable.
However, according to the design review / reconstitution, the FSAR is incorrect and the SAS flow rate changes due to changes in spray flow and changes in SAT level.
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To assess the safety significance of a high NaOH flow rate on the sump pH, the staff ran the computer code using trots that would conservatively maximize 4
the pH values in the sump during the event..The staff did not model the change in SAS flow with SAT level, but used an SAS flow rate of 68 gps. Note:
this may not bound the actual system flow rate -- Braidwood should have calculations and/or an operability determination to justify the actual system settings since they are not consistent with the design reconstitution (see next section).
The staff ran each of the large break LOCA single failure sets for the following cases:
(1) the case where the operators took proper action to close l
the SAS control valves after the SAT Lo-2 alarm had actuated in the control to-2 alarm (2) the case where the operators failed to take proper action at the room; and and the SAT had been emptied of its NaOH inventory. Tables 2 and 3 in Appendix 2 provide the staff's results for the first and second case, respectively., The staff's assessment indicates that althou;h the pH in the containment sump will be sufficiently basic (pH > 7.0) to maintain control of radioactive iodine fission products during the postulated event, the pH will not exceed 10.0 even for the high SAS flow rate (68 gpm) condition and the case where the operators failed to close the SAS control valves after the SAT Lo-2 alarm had actuated in the control room.
l It should be noted that Comed's calculations for the sump pH are based on more l
complex calculational methods. Comed's methods are based on solving a series of simultaneous equations that include mole balance equations, tonic strength equations, charge balance equations, and equilibrium equations for boric acid, and the dimer Comed's lead technical : trimer, and tetramer types of polyborate molecules.
hemical engineer has indicated that inodeling the pH of the sump in accordance with such methods may yield pH's in excess of 11.0 for the high SAS flow condition (68 gpm). In comparison, the results of the staff's l
computer code runs for the high SAS flow condition at Braidwood indicates that the pH of the sump should range from 7.2 - 9.5.
Thus, even if the pH of the containment sump exceeded 10.5, the timeframe at which the sump pH would exceed 11.0 would be limited in extent; even if Comed's calculational model was a more appropriate model to use in this case.
The staff addressed the impact of a short-duration, high pH condition. The staff does not believe this condition will have a significant impact on the systems inside containment. Due to the short duration, the elevated pH is not expected to cause caustic cracking of stainless steel components or cause significant corrosion of instrumentation or other required equipment.
o The staff concludes that if the SAT 1evel were 90% instead of mid-level, the SAS flow would be higher; however, the SAS should still meet the intent of the TS of retaining iodine in the sump and preventing damage to equipment inside containment. Consequently, this has minimal safety significance.
l 3.3 At Byron /Bralkood, sp. h additive flow appartntly cannot be maintained at 55-60 spe free a fu), SAT to enpty. Each plant uses different eductor native flow and slaulates the SAT at a different level during survei11ance testing. T5 do not spectfy survei11ance initial conditions. At what conditions should the surveillance be performed at these stations?
Test conditius should be consistent with the most up-to-date design bases for the ECCS, CSS, and SAS. Items to consider include:
(1) SAT level in comparison to TS limits; (2) Na0H concentration in comparison to TS limits; (3) eductor loop valve positions and/or flow rates in comparison with design parameters; (4) SAS valve position; and (5) adjustment factors for flow rates.
Conditions for the test should be set to produce flows representative of those to be expected during a specific period (s) of SAS operation during a DBLOCA.
NRR conducted. a brief review of the Byron and Braidwood Stations' design bases for the SAS by reviewing information contained in the Byron and Braidwood Stations TS bases, UFSAR, and the " Byron /Braidwood Stations, Units 1 and 2 Systes Design Description for Containment Spray," (SDD) which was submitted to the NRC on November 13, 1996. Based on the November ll, 1996 submittal, the SDD contains the most current design information. The SDD states the eductor flow should be set for NaOH flow of 55-60 gpm (equivalent to 68-74 gpm primary water, which reads as 62-67 gpm on F1-CS015/16 due to density correction) with the SAT at high level and the eductor motive flow equal to the values determined during pre-operational testing (about 130-135gpm). This provides the maximum NaOH flow during system operation. The design basis calculations address the variations in actual system performance (i.e., variation in CS flow,variationinSATlevel,etc.).
3.4 At Zion, the' CSS and SAS for Units I and Z are designed such that the Ms0H flow must be adequate to add the required snount of caustic to the containment susp prior to emptying of the WST. Zion malatains a HaOH concentration of about 40 wt.~% in the SAT (T5 require > 30 wt.-%).
Accident analysis at Zion takes credit for only one C5 pump educting caustic at 50 spe. During a LOCA, the W ST could empty in as little as 34 minutes (as stated in the UFSAR, Appendix 6, p. 68-5). Will an adequate snount of Ms0H be added in this tine? In addition, CoaEd has no licensing, TS, or rugulatory requirement to maintain a nitrogen blanket on the SAS at Zion. Is there a negative effect on the caustic solution at Zion from being vented to atmosphere instead of having a nitrogen blanket on the spray additive tank?
The staff perferned an independent analysis of Zion's ECCS, CSS, and SAS responses during a postulated DBLOCA, considering the cases of either one,
I I.
two, or three CSS pumps operating. The input data were selected to give the lowest pH response of the sump inventory over time. The staff's analysis indicates that, based on the event scenario of havin pumps operating, the RWST can empty in as little as g two of the three CSS 25 minutes.
In all l
cases, the pH of the containment sump quickly rose above 7.0 and steadily increased to 8.3 - 8.5 at the time of CSS switch-over to recirculation mode (which terutnates NaDH addition). The pH profiles obtained in the staff's simulations are consistent with the pH profile in Figure 68-1 of Appendix 6B,
" Iodine Removal Effectiveness Evaluation of Containment Spray System," to Zion's UFSAR. Therefore, Zion's design appears acceptable with respect to sump pH during a LOCA.
The purpose of a nitrogen blanket on an SAT is to aravent the gradual i
dissolutionofatmosphericCOtionandreducethesolution'sabilityto into the NaOH solut' on. The CO will, over time, acidify the caustic solu l
perform its design function. Based on the limiting cases run for Zion, there appears to be ample margin in the system design to account for some acidification of the solution. Zion's practice of maintaining higher than l
30 wt-% solution provides additional margin. Therefore, the safety significance of maintaining a nitrogen blanket appears small. Due to the small safety significance, NRR does not support pursuing a bachfit analysis to impose the requirement for a nitrogen blanket at Zion. However, since the l
Plant does not maintain a nitrogen blanket on the SATs, Zion's design bases l
should account for CO, in the NaOH solution in the calculations for spray and l
sump pH.
3.5 At all three sites, the effect on equipeent Environmental Qualification (EQ) of high CS pH (>10.5 needs to be assessed.
about this natter are docu)eented in Attacheent 2. Westinghouse concerns l
I Additionally, the use of Vantage 5 fuel necessitates a higher RWST baron concentration (apparently, the previous mininus was 2,000 ppe; the current T5 band is 2,4004,600 ppe). The effect of this on spray and susp pH requires assessment.-
According to the 500 at Byron and Braidwood Stations; the CSS /SAS function is to limit spray and sump pH to <10.5.
This is significantly less than the Westinghouse predictions of spray pH as high as 12. The staff's calculations i
support Comed's calculations that sump pH will be <10.5.
Note: the SDD does state that, at Byron and Braidwood Stations, spray pH can increase to 11.4 under the conditions where CS pumps switch to recirculation mode before the SAT has drained. For these cases there is a brief duration where the caustic is mixed with recirculated sump fluid, which is already neutral or basic. The 500 states there is no EQ concern due to the short duration of the high pH condition. The staff concurs that a short duration should not cause a significant degradation of equipment.
Both Comed's and the staff's analysis of spray and sump pH considered the TS maximum boron concentration of 2,600 ppe in the RWST for cases where low pH is
1.' ',
~
9 limiting. The resulting pH, as described in Section 3.1, is acceptable for the 11mLting cases.
4.0 CONCLUSION
The staff has completed its review of the SAS issues at the Byron, Braidwood, and Zion Stations, j
At Byron, the surveillance was conducted such that SAS flow rate is 55-60 gpm when the SAT is full and the eductor motive loop flow is 150-155 gpm. The staff analyzed this condition (SAS flow approximately 42-46 gpa when motive l
loop flow is in the expected range, 130-135 gpm) and determined the resultant pH was acceptable and meets the intent of the TS.
At Braidwood, the surveillance was conducted such that SAS flow rate is 55-60 l
gpm when the SAT is at mid-level and eductor motive flow is 130-135 gpm. SAS flow will be higher when the SAT is at the TS-required level of 78-90%. The i
staff has not modelled the actual system condition, but has shown that an SAS I
flow of 68 gpm meets the intent of the TS. Therefore, the Braidwood as-left condition should meet the intent of the TS.
l The spray additive design at the Zion Station appears to be consistent with the design described in Zion's FSAR. However, Zion should address the issue of acidification of the NaOH solution which may occur since the SAT is exposed to the atmosphere (i.e. vented). Zion should either consider adding a nitrogen blanket, such as that used at other plants, nr should include the acidification in the design basis. Note: Zion has analyzed samples of the solution and determined tie concentration of carbonic acid to be minimal.
The staff has also determined that the apparent discrepancies have minimal safety significance.
e e
G I
0 e
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APPDCIX 1 BYRON /BRAIDif000ANDZIONSTATION J
TEcati! CAL SPECIFICATIONS FOR THE BORATD SYSTERS AND SPAAY ADDITIVE SYSTDIS t
e a
e APPINDIX 1-1
g 11MfTING CO*mfTf0N F04t OPERATION 3.5.1 Each Raaetor Coolant System accumulator shall be OPERA 8LE with:
The isolation, valve open and power removed.
a.
6.
A contained borated water level of between 315 and 835, c.
1)' A boron concentration between !!00 and 2400 ppe, 2)** A boron concentration between 1g00 and 2100 ppe, and d.
A nitrogen cover-pressure of between 502 and 647 psig.
APPtitAtttfTY: fCOIS 3, 2. and 3*.
ALIIDN:
a.
With one accumulator inoperable, except as a result of a closed isolation valve, restore the inoperable accumulator to OPERABLE status within I hour or be in at least HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in HOT SHUTDOWN within the following 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />.
b.
With one accumulator ino erable due to the isolation valvs being closed, either famediate y open the isolation valve or be in at
('
1 east HOT STANDBY within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in HOT SHUTDOWN within the following 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />.
Stf9VEitiaNEE RE0tff REMENT$
4.5.1.3 Each accumulator shall be demonstrated OPERABLE:
a.
At least once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> by:
1)
Verifying the contained berated water level and nitrogen cover-pressure in the tanks, and 2)
Verifying that each accumulator isolation valve is open.
t.
' Pressurizer pressure above 1000 psig.
W4pplicable to Unit 1.
Applicable to Unit 2 after cycle 5.
- Not applicable to Unit 1. Applicable to Unit 2 until completion of cycle 5.
BYRON - UNIT 5 1 & 2 3/4 5-1 AMgENT NO. 65 aj Cc Besh,d tgs 2IIN
@
- en*w
3/4.5.2 ECC5 5UBSYSTEMS - T;,,1350' 11MITING CONDITION FOR OPERATION 3.5.2 Two independent Energency Core Cooling System (ECCS) sesystems shall be OPERABM with each sesystas comprised of:
a.
One OPERABE centrifugal charging pup, b.
One OPERABM Safety Injection pump, c.
One OPERABLE RNR heat exchanger, d.
An OPERABLE flow path' pable of taking suction from the refueling water storage tank on. Safety Injection signal and automatic opening of the containment sump suction valves.
APPLICABILITY: MODES 1, 2, and 3.
t ACTION:
a.
With one ECCS subsystem inoperable, restore the inoperable subsystem to OPERABLE status within 7 days or be in at least HOT STANDBY l
within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in HOT SHUTDOWN within the following 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />.
b.
In the event the ECCS is actuated and injects water into the Reactor Coolant System, a Special Report shall be prepared and submitted to the Commission pursuant to Specification 6.9.2 within 90 days describ-ing the ciremstances of the actuation and the total accumulated actuation cycles to date. The current value of the usage factor for each affected Safety Injection nozzle shall be provided in this Special Report whenever its value exceeds 0.70.
^
the discharge paths of both Safety Injection pumps may be iso-
=purtng PEDE 3 lated by closing SI 8835 and a portion of the discharge paths ol' both RHR pumps say be isolated by closing either.518809A or 5188098 for a period of up to 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> to perform surveillance testing as required by Specification 4.4.5.2.2.
When either SI4809A or 5188098 is. closed and pressurl er pressure is below 1000 psi, the accumulators shall be OPERABLE with their isolation valves either c osed, but owrgized, or open.
i BYRDN - UNITS 1 & 2 3/4 5-3 AMENDMENT NO.14 l
M*' I I T:i
I e MastucY CMI COOLING SYITDP l:
(
$0sYrituutet AtWf tDOffs (Continued) 1)
For ail accessible atens of the contatsment prior to establishing CD C A110 0ff INTE&AITY, and 2)
Of the steas affected slitAfn containment at the cespletion of each contalment entry when CDCA!WO(T INTEGAITY is established.
d.
At least asce per 38 aseths ty:
j 1)
Vertfying estanstic faterteck actfen of the RNR Systas free the Reacter Coelant Systas by ensuring that ary simulated er actual Asseter Coolant Systas pressure signal greater than er equal to 360 psig prevents the valves fres befag opened.
2)
A visal inspection of the contalment sep ar.d verifying that the subsystas suction inlets are not restricted by debris and that the sump camponents (trash racks, screens, etc.) show no evidence of structural distress er abnormal corrosion.
l e.
At least once per 18 months, durfag shutdown, by:
1)
Verifying that each autenatic valFe in the flow path actuates to its correct position en a safety Injection test signal and (f
en a AWST Level-Low Low test signal, and l
2)
Verifying that each of the fo11 swing pumps start automatically spon receipt of a safety 2njection actuation test signal:
a)
Centrifugal charging pump,
~
b)'
Safety Injection pump, and c)
RHR pump.
f.
gy verifying that each of the following pumps develops the indicated differential pressure on recirculation flow when tested pursuant to
. Specification 4.0.5:
2)
Centrifugal charging pump y,2396 psid, 2)
Safetyinjectionpump 41412psie,and 3)
RHRpap In accordance with Figure 4.5-1
(
BYRON - UNITS 1 & 2 3/4 5-5 AMENDMENT NO. 38 50311990
u JiiiiF...=;::sd. :rme:.._ --_-_as--
5
. r-
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5 E
ilefweed Potats en the tvever
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187 L-i
=
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200 500 181 I
8000 177 3500 178 2000 1H T ~"
190- - - - - -
.2500 159 t
=
3000 155
~;
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500 I43 130_
1)3 4500 127
- C y 170-
=
5000 112 g
160
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=ACCEPTASLE T
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= -. -
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_ _. = =
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8060 2060 3060 A600 5000 l
\\
RNR PLMP FLOW (GPM)
FIGURE 4.5-1
~
f h
RESIDUAL MEAT REMOVAL PUMP MINIMUM ACCEPTA8LE PERFORMANCE CURVE SYRON
- UNITS 1 & 2 3/4 5-6a AMENDMENT No. 3 G
+
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~
l f
S/4.5,4 tCC$ SUBMTDes - T.1115 Twut 04 E00At TO 200*F j
g fEffYRIffR LIVfL StfATf4 TMut 5 p[tCDff (LfYEL 409,l')
l Lia m ai CONDITION FOR OPERAT! M l
3.8.4.1 All Safety injectise p g shall be inoperable.
APPLICA81LITY: sco! 5 with pressurizer level greater than 5 percent, and 900f 5 with pressvrtzer level greater than 5 percent and the reacter vessel head resting en the reactor vessel flange.
E:
With a safety Injection OPERABLE,restoreallSafetyInjectionpumpsto inoperable states within 4
$UWfittANCE REQUIRDtD(TS:
4.5.4.1 All Safety Injection pumps shall be demonstrated ihoperable* by
{.
verifying that the actor circuit breakers are secured in the open position at Isast once per 22 hours2.546296e-4 days <br />0.00611 hours <br />3.637566e-5 weeks <br />8.371e-6 months <br />.
l-1
- An inoperable pg may be energized for testing or for filling accumulators provided the discharge of the pump is isolated from the RCS by a closed isolation valve with power removed from the valve operator, or by a manual
(-
isolation valve secured in the closed position.
8YRON - WITS 1 & 2 3/4 5-9 AMENDMD(T N0. 38 AUG811990 em
-?
" 3.5.5 The refueling water storage tank (RWST) and the beat traced portfor.
ef the RWIT vent path shall be GPIRABLE with s.
A minimum contained berated water level of 895, b.
3)* A boron concentration between 3300 and 2500 ppa, 2)** A minisus borsa concentration of 2000 ppa, c.
A minimum water temperature of 35'F, and d.
A maximum water temperature of 300*F.
APPLIfAllLITY: 9100[5 3, 2, 3, and 4.
EIEN:
With the RWIT inoperable, restors the tank to CPERABLE status within I hour er be in at least HOT STANDBY within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in COLD SHUTDOWN within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.
SUeVffttaNtt REOUTREMENTS 4.5.5 The RWST shall be demonstrated OPERABLE:
s.
At least once per 7 days by:
(,
1)
Verifying the contained borated water level in the tank, and
!)
Verifying the boren concentration of the water.
l b.
At least once per 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> by verifying the RWST temperature when l
the outside air temperature is either,ess than 35'T or greater than 200*f, and i
c.
At least once per 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> by verifying the RWST vent path temperature to be greater than or equal to 35'T when the outside air temperature is less than 35'F.
l
- Applicable to Unit 1. Applicable to dntt I after c cle 5.
,,Not applicable to Unit 1. Applicable to Unit ! untf1 completion of cycle 5.
SYRON - UNITS 1 & 1 3/4 5-11 AMENDMENT NO. 65 E Il IM
4 s..
'J CONTAINMENT SYSTEMS
$ PRAY ADDITIVE SYSTEM
- LIMITkN3 CONDITION FOR OPERATION 3.6.2.2 The Spray Additive systes shall be OPERABLE with:
a.
A spray additive tank containing a level of 6etween 78.E5 and 90.3%
of between 30% and 36% by weight NaOH solution, and b.
Two spray additive eductors each capable of adding NaOH solution from the spray additive tank to a Containment Spray Systes pump flow.
APPLICAl!LITY: MODES 1, 2, 3 and 4.
ACTION:
With the Spray Additive System inoperable, restore the system to OPERABLE status within 7 days or be in at least HOT STANDBY within the next 5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />; l
restore the Spray Additive System to CPIRABLE status within the next 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> or be in COLD SHUTDOWN within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.
SURVE!LLANCE REQUIREMENTS j
4.6.2.2 The Spray Additive Systen shall be demonstrated OPERABLE:
s.
At least once per 31 days by verifying that each valve (sanual, power operated, or automatic) in the flow path that is not locked, sealed, or otherwise secured in position, is in its correct position; l
3.
At least once per 5 months by:
I 1)
Verifying the contained solution level in the tank, and 2)
Verifying the concentration of the NaOH solution by chemical analysis.
c.
At least once per 18 months during shutdown, by verifying that each automatic valve in the flow path actuates to its correct position on a Containment spray Actuation test ~signall and d.
At least once per 5 sars by verifyinn each water flow rate, es!vivalent to 55(+5, 0) ~ gallons per a nute for 30% NaOH free the j
ec>uctor test cor.nect ons in the Spray Additive system:
+6 1)
CS264 64 -0 spa (Train A), and
+5 2)
C5268 68 -0 ppa (Train B).
BYRON
- UNIT 51 & 2 3/4 6 14 AMENOMENT NO.14 9,w,,
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4 APPDWII 2 RESULTS OF CORPUTDt CODES RUN FOR A15E55RDIT OF C0KTAINMDrf SURP pH DURING A POSTULATED DEsisN BA315 LOCA:
SYRON, SRA! WOOO AND ZION STATIONS O
I e
0 0
e i
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APPENDIX t-1 0
4 6 4 eAGet S S 9 e 59 m*
99 9
v-
,8.
Table 1 Low pH Computer Modeling Results for Byron large Break LOCA Events Time & pH g
All P aps Accumulator ECCS SAS Valve CS$
Initiate Complete awap Closed Swap Injection Time pH Time pH Time pH Time pH Time pH CN Elec. Fail.'
A or 8 Train 0.75 5.5 1.25 7.2 38.8 8.3 65.8 B.5 73.2 8.5 RHR Pump Fails to Start 0.75 5.5 1.25 7.5 27.2 B.4 32.8 8.E 42.2 B.6 SAS'Inj. Valve rails to open 0.75 5.5 1.25 7.2 23.2 B.0 65.2 B..I 35.8 B.1 A CSS Pump fails to Start 0.75 5.5 1.25 7.2 27.8 8.1 65.2 b.4 55.7 B.3 N
0.75 5.5 1.25 7.5 23.2 B.3 32.8 B.4 35.8 B.5 g ilure egute,
campmee made ver we 1:
fart vetumme BWsf wluse of 458000 patters tonalaus deelyn welues)
SAT welume of 3950 settens (-775 full
- sintam ettewed by TI) htrat f ana eWsf beels ocid sensentration of 0.51 noter (- 500 gen Beren - saatam altamed by 18)
SC8 heels ocid sententration of 0.092S Iteter (*1000 ppm Seren
- start of ryste B)
SCS Lisa sensentrettm of 0.000058 Iteter (0.40 sem Li = end of cycle LI)
Assumuteter horts seld sensentratte of 0.I22 meter (2400 pen 8. maalma ettened by Ts) acts and ces Ftas notse (unime duefyi fIou rotes)
- As frein est Pumps 3285 gun er e sun
- e* Train ris hae: 3Ftl som er 9 eps SAs Ptow sete: 42 sue or e ess cheesine heos flow sets: 350 sum Elph esed Safety injectlen haps: 450 gum Les tend (Rum) safety Injestlen hagas 3000 gas or 0 gum APPEND 11 1-1 e
- ' :;p? :._
- g e.
Table 2 High pH Computer Modeling Results for Byron Large Break LOCA Events
- Assumes Operators Take Proper Action to Close SAS Valves at Lo-2 Time & pH All Pap Accmulator ECCs SAS Valve
- C55
)
Initiate Complete swap Closed Swap Injection Time pH Time pH Time pH Time pH Time pH CM Elec. Fail.
A or B Train 0.75 6.3 1.25 8.2 32.8 8.9 55.8 9.2 73.2 9.4 RHR Pump Fails to Start 0.75 6.3 1.25 8.2 22.2 9.1 28.2 9.2 37.2 9.4 SAS Inj. Valve Fails to Open 0.75 6.3 1.25 7.9 19.2 8.4 55.8 9.0 31.8 8.6 A CSS Pump Fails to Start 0.75 6.3 1.25 7.9 23.2 8.6 55.8 9.0 56.2 9.0 No Failure 0.75 6.3 1.25 8.2 19.2 8.9 28.2 9.1 31.8 9.1 Ramute ta tammuter cade far fakta la fank Wahame ausf vetume of 395500 setters (eintam siselm wtme)
SAT estas of 5000 setLars (-1905 fwlt + more then altamed by 18) tanrantrattana twat heels ocid sensentratim of 0.tts stater (- 500 pse Seren + alnlam ellemed by 18)
RCs boris ocid eencontratten of 0.0 sketer (=0 pm 3eren + end of eyste Beren)
BCS L10m sententration of 0.00016 Inster (- t
- 9.60 pen LI + 2
- end of syste LI)
Asasuteter horie esid sensentratten of 0.203 Iteter (2200 paa B + sintam ettewed by 18) eDEB sd CEB Flas estes paslag shale flew estes)
- A* Train CBS hap 3285 gust er o som age frein C88 haps 3Fft som se e see SA8FlesRates et en er 0 ges Chemire hage flew sete 850 mm Eigh Deed Gefety injectlen hase 650 gum Les teed (tut) tafety injeetten hayas a000 pm er e en APPENDIX 2-3 l
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' Table 3 High pH Computer Modeling Results for Byron Large Break LOCA Events
- Assumes Operators Fall to Take Proper Action to Close SAS Valves at the Lo-2 Alam Setpoint and That the Inventory in the SAT Empties Time & pH All Paps Accumulator ECCS SAS Valve C55 Initiate complete swap Closed swap Injection Time '
pH.
Time pH Time pH Time pH Time pH CM Elec. Fall.
A or B Train 0.75 6.3 1.25 8.2 32.8 8.9 73.7 9.4 73.2 9.4 l
RHR Pump Falls to Start 0.75 6.3 1.25 B.2 22.2 9.1 36.8 9.4 37.2 9.4 SAS Inj. Valve Fails to Open 0.75 6.3 1.25 7.9 19.2 8.4 73.8 9.3 31.8 8.6 A CSS Pump Fails to Start 0.75 6.3 1.25 7.9 23.2 B.6 73.8 9.4 56.2 9.0 l
No Failure 0.75 6.3 1.25 B.2 19.2 B.9 36.8 9.3 31.8 9.1 Isuman to tammutar Cade far Table Is Tant vet ens twf wies of 395500 setters (eintam doelp wtues)
SAT wtsme of s000 settone (-1901 fwlt. aere than etlosed by 18) fancantratfana BWT berls ocid omrentratten of e.tt3 noter ( 3500 ppm Beren. alnlam ettaund by 18)
BCs horic acid eencontratten of 0.0 meter (-e pen toren. and of cycle toren)
SC8 LION sencontratten of 0.00014 meter (* 2
- 0.40 psm L1 + 2
- end of cycle L1)
Asamuleter horis ocid eencontration of 0.203 meter (2200 ppe 8 elatan ettemed by 18)
NES and Ems Flas notes tuelse deelp fles rotes) l
- A* Train tal hoqps 3285 sp or a ses 888 frein Css has4 3??5 som er e gym SA8 fles note 60 gas or e ess Chargins hape flem sets: 550 gun Wish eesd Defety injectlen Mass: 650 pse tow toed (tot) asfety injettlen hape 3000 gym er a spa l
APPENDIX Z 4
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Table 4 Loit pH Compute'r Modeling Results for' Zion L'arge Break LOCA Events -
- . V...
Accident Analyses Assumes One, Two er Three CSS Pumps Running i
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SAS Valve C55 All Pept' Accumulato -
WS ECCs'.g J
Initiate.-
Complete.,.
//} $wap ci.9
, Closed swap InjectionN
,?'e W M u"-
Time
'pH Time pH' Time'
' pH Time pH Time pH Two C55 Pumps o:
Fall to Start 0.75 6.3 1.25 7.3 '
19.2.
B.0' 50.0 B.3 43.2 8.3
,4 f?.;
s id'. M.
One Ess Pump Fails to Start 0.75 6.3 1.25' 7.5' 16.5 ' S.3 25.0 B.4 27.2 E.4 No Failure 0.75 6.3 1.25 7.7 14.8 B.3' 16.8 B.3 22.8 8.4 11 mats to tammuter Caen far fable 4 fank Wahama SWT wies of 398000 settone (eintes deste eetme)
SAT wies of 3600 settens (elnlam attened Dr 18)
Cancertrattens BWT boris acid sensentratf an of e.343 meter (- 3600 pas seren - naslam br elastm)
Act heels acid sencontration of 0.1M meter (-1500 ppm Beren
- est. of beglemtre cycle Seren)
SC8 Lige sencontretlen of 0.00034 meter ( 3.44 ppm Li
- est. of beelmire syste LI)
Assauteter berls acid senesntratten of 0.363 meter (3600 ppm O = maalma by closte)
SDCB eid CBE F(es totas l
- As Train tst haya th gun (pap twout flew rete) age frein est hap 6000 gym (pump runaut fles rete) er e gun
- C* Treln est hap 6000 ass (pg reaut flow rete) er e som SAS flew totes: 50 spa (reted doel m fles rete) er a spa Charging have flew tote 950 spa (map reaut flew rate) sigh toed Safety injection haps 650 spa (map reaut flow rete) l Law moed (ent) Safety injectlen hape 4500 spa (psy runaut flew rete) i I
1 APPENDIX I-5
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Assumpthns for Computer Code Runs >
Simplified Model - (!) No motive flow modeled, spray additive (NaOH) is pulled directly into the containment spray flow path; (2) chemistry reactions assume no poly-borate complexes exist in equilibrium with boric acid.
At 15 seconds - No injection methods or sprays are initiated; RCS blowdown at 15 seconds is 335 complete.
At 45 seconds - The maximum RCS blowdown volume in the design basis accident analysis is lost to the sump; Accumulators have injected 60% of their inventory into the sump; Both ECCS and CSS systems pumps initiate and both the ECCS and CSS are aligned to the RWST.
At 1.25 Minutes (75 seconds) - Accumulators have injected 100% of their inventories to the sump.
Operatcrs swap ECCS suction to the containment sump when the remaining volume in the RWST reaches the setpoint for the Lo-2 Alars (201800 gallons).
Completion of the switch of the ECCS to recirculation mode takes an additional six minutes to complete; the flow rates from the charging, high head safety injection, and low head safety injection (RliR) during this time are equivalent to the flow rates of these systems during the injection phase.
Operators swap CSS suction to the containment sump when the remaining volume in the RWST reiches the setpoint for the Lo-3 Alars (27500 allons for B/8; o Complet$on of the switch ofallons at Zion)irculation mode takes an the CSS to rec additional six minutes to complete; the flow rates from the CSS trains during this time are equivalent to the flow rates of there systems during the injection phase.
t Operators close the' injection valve for the SAS when the remaining volume in the SAT reaches the setpoint for the Lo-2 Alars (1200 gallons for B/8,160 gallons for 21on Only one active or passive failure can),be modeled to o'ccur during the accident scenario s.
An exceptiontothisassu,mpt$on,nomultiplefailuresassumed.is that, consistent f
the Zion FSAR, for one scenario, two containment spray pumps were assumed,to fall to start simultaneously.
i l
i APPENDIK 2-6
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