NL-15-001, Watts Bar, Unit 1 - Application to Revise Technical Specification 4.2.1, Fuel Assemblies, (WBN-TS-15-03): Difference between revisions

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#REDIRECT [[CNL-15-001, Watts Bar, Unit 1 - Application to Revise Technical Specification 4.2.1, Fuel Assemblies, (WBN-TS-15-03)]]
| number = ML15098A446
| issue date = 03/31/2015
| title = Watts Bar, Unit 1 - Application to Revise Technical Specification 4.2.1, Fuel Assemblies, (WBN-TS-15-03)
| author name = Shea J W
| author affiliation = Tennessee Valley Authority
| addressee name =
| addressee affiliation = NRC/Document Control Desk, NRC/NRR
| docket = 05000390
| license number = NPF-090
| contact person =
| case reference number = CNL-15-001, L44 150331 002, WBN-TS-15-03
| document type = Letter type:NL, Technical Specification, Amendment
| page count = 66
| project =
| stage = Request
}}
 
=Text=
{{#Wiki_filter:1101 Market Street, Chattanooga, Tennessee  37402
 
CNL-15-001  
 
March 31, 2015
 
10 CFR 50.90
 
ATTN:  Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555-0001 Watts Bar Nuclear Plant, Unit 1 Facility Operating License Nos. NFP-90 NRC Docket No. 50-390
 
==Subject:==
 
==References:==
: 1. NRC letter to TVA dated May 4, 2009, "Watts Bar Nuclear Plant, Unit 1 - Issuance of Amendment Regarding the Maximum Number of Tritium Producing Burnable Assembly Rods in the Reactor Core (TAC No.
MD9396)," ADAMS Accession No. ML090920506.
: 2. TVA letter to NRC dated May 23, 2002, "Watts Bar Nuclear Plant - Request for Additional Information (RAI) Regarding Radiological Impact (TAC NO. MB1884)," ADAMS Accession No. ML021490139.
: 3. NRC letter to TVA dated August 20, 2002, "Watts Bar Nuclear Plant, Unit 1 - Environmental Assessment and Finding of No Significant Impact for Incore Irradiation Services for the U.S. Department of Energy's Tritium Production Program (TAC No. MB1884)," ADAMS Accession No. ML022320905.
In accordance with the provisions of 10 CFR 50.90, "Application for amendment of license, construction permit, or early site permit," Tennessee Valley Authority (TVA) is submitting a request for an amendment to Facility Operating License No. NFP-90 for the Watts Bar Nuclear Plant (WBN), Unit 1.
 
U. S. Nuclear Regulatory Commission CNL-15-001
 
Page 2 March 31, 2015
 
The proposed change would revise WBN, Unit 1 Technical Specification (TS) 4.2.1, "Fuel Assemblies," to increase the maximum number of Tritium Producing Burnable Absorber Rods (TPBARs) that can be irradiated per cycle from 704 to 1,792. This change is analogous to the change approved by NRC in WBN, Unit 1 License Amendment 77 (Reference 1), which increased the maximum number of TPBARs that can be irradiated from 400 to 704. The proposed change would also revise TS 3.5.1, "Accumulators,"
Surveillance Requirement (SR) 3.5.1.4 and TS 3.5.4, "Refueling Water Storage Tank (RWST)," SR 3.5.4.3 to delete outdated information related to the Tritium Production Program.
to this letter provides a description of the proposed changes, technical evaluation of the proposed changes, regulatory evaluation, and a discussion of environmental considerations. Attachment 1 to Enclosure 1 provides the existing TS pages marked-up to show the proposed changes. Attachment 2 to Enclosure 1 provides the retyped TS pages incorporating the proposed changes. Attachment 3 to Enclosure 1 provides the existing TS Bases pages marked-up to show the proposed changes. to this letter provides an update to the information TVA provided to the NRC regarding the environmental impacts associated with tritium production from irradiating as many as 2,304 TPBARs to support WBN, Unit 1 License Amendment 40 (Reference 2). The NRC used this information in their Environmental Assessment and Finding of No Significant
 
Impact for WBN, Unit 1 License Amendment 40 (Reference 3). Enclosure 3 provides the list of new regulatory commitments.
 
TVA requests approval of the proposed License Amendment by August 31, 2016, to support a planned increase in TPBAR inventory for the WB N, Unit 1 Cycle 15 refueling outage in the spring of 2017 to support national security needs. The License Amendment will beimplemented prior to startup from the outage where the increased number of TPBARs is inserted in the reactor core.
 
TVA has determined that there are no significant hazards considerations associated with the proposed change and that the change qualifies for a categorical exclusion from environmental review pursuant to the provisions of 10 CFR 51.22(c)(9).
 
The WBN Plant Operations Review Committee and the TVA Nuclear Safety Review Board have reviewed this proposed change and determined that operation of WBN in accordance with the proposed change will not endanger the health and safety of the public.
 
Additionally, in accordance with 10 CFR 50.91(b)(1), TVA is sending a copy of this letter and the enclosures to the Tennessee Department of Environment and Conservation.
 
There are two new regulatory commitments associated with this submittal. Please address any questions regarding this request to Mr. Edward D. Schrull at (423) 751-3850.
 
Page E1-1 of 18
 
==Subject:==
Application to Revise Technical Specification 4.2.1, "Fuel Assemblies," (WBN-TS-15-03) 1.0
 
==SUMMARY==
DESCRIPTION
 
===2.0 DETAILED===
DESCRIPTION
 
===3.0 BACKGROUND===
 
==4.0 TECHNICAL EVALUATION==
 
4.1 Post-LOCA Subcriticality Evaluation 4.2 TPBAR Tritium Release Rate
: 5. REGULATORY EVALUATION
 
===5.1 Applicable===
Regulatory Requirements/Criteria  5.2 Precedent
 
===5.3 Significant===
Hazards Consideration
 
===5.4 Conclusions===
: 6. ENVIRONMENTAL CONSIDERATION
: 7. REFERENCES
 
ATTACHMENTS
: 1. Proposed TS Changes (Markups) for WBN, Unit 1
: 2. Proposed TS Changes (Final Typed) for WBN, Unit 1
: 3. Proposed TS Bases Changes (Markups) for WBN, Unit 1
 
Page E1-2 of 18 Pursuant to 10 CFR 50.90, the Tennessee Valley Authority (TVA) is submitting a request for a change to Facility Operating License NPF-90 for Watts Bar Nuclear Plant (WBN), Unit 1. The proposed change will revise Technical Specification (TS) 4.2.1, "Fuel Assemblies," to increase the maximum number of Tritium Producing Burnable Absorber Rods (TPBARs) that can be irradiated per cycle from 704 to 1,792. This change is analogous to the change implemented in WBN, Unit 1 License Amendment 77 (Reference 1), which increased the maximum number of TPBARs that can be irradiated from 400 to 704, and has been evaluated using the methodology employed for WBN, Unit 1 License Amendment 77 (Reference 1). Specifically, a representative core design with 1,792 TPBARs was developed and a post-loss of coolant accident (LOCA) analysis was performed for this core design using the same methodology employed in WBN, Unit 1 License Amendment 77. This analysis demonstrated post-LOCA subcriticality using the current Emergency Core Cooling System (ECCS) minimum boron concentrations. No credit for control rod insertion was assumed. 
 
The proposed TS changes will also revise TS 3.5.1, "Accumulators," Surveillance Requirement (SR) 3.5.1.4 and TS 3.5.4, "Refueling Water Storage Tank (RWST)," SR 3.5.4.3 to delete outdated information related to the Tritium Production Program.
 
The proposed change is required to support a planned increase of TPBAR inventory in the WBN, Unit 1 Cycle 15 refueling outage in the spring of 2017 to support national security needs. 
 
This license amendment request (LAR) revises TS 4.2.1, "Fuel Assemblies," to increase the maximum number of TPBARs that can be irradiated per cycle from 704 to 1,792. 
 
In addition, this LAR will revise TS SR 3.5.1.4, "Accumulators," to delete the associated Note and the table related to TPBARs and revise the SR to read:
 
Verify boron concentration in each accumulator is > 3000 ppm and
< 3300 ppm.
 
This LAR will also revise TS SR 3.5.4.3, "RWST," to delete the associated Note and the table related to TPBARs and revise the SR to read:
 
Verify boron concentration in the RWST is > 3100 ppm and < 3300 ppm.
to Enclosure 1 provides the existing TS pages marked-up to show the proposed changes. Attachment 2 to Enclosure 1 provides the retyped TS pages incorporating the proposed changes. Attachment 3 to Enclosure 1 provides the existing TS Bases pages marked-up to show the proposed changes and is provided for information only. The changes to the TS Bases are controlled by WBN, Unit 1 TS 5.6, "Technical Specification (TS) Bases Control Program."  Approval of this LAR will authorize the irradiation of up to a maximum of 1,792 TPBARs.
 
Page E1-3 of 18 The Department of Energy (DOE) and TVA have agreed to cooperate in a program to produce tritium for the National Security Stockpile by irradiating TPBARs at WBN, Unit 1.
TPBARs are similar to standard burnable poison rod assemblies (BPRAs) inserted into fuel assemblies. The BPRAs absorb excess neutrons, and help control the power in the reactor to ensure an even power distribution and extend the time between refueling outages. TPBARs function in a matter similar to a BPRA, but TPBARs absorb neutrons using lithium aluminate instead of boron. Tritium is produced when the neutrons strike the lithium material. A solid zirconium material in the TPBAR (called a "getter") captures the produced tritium. Most of the tritium is contained within the TPBAR. However, a small fraction of the tritium will permeate through the TPBAR cladding into the reactor coolant system (see Enclosure 2). After the TPBARs are removed from the core and shipped to a DOE extraction facility, the TPBARs are heated in a vacuum at high
 
temperature to extract the tritium.
 
The first TPBARs irradiated in WBN, Unit 1 were in four lead test assemblies (LTAs),
containing a total of 32 TPBARs during WBN, Unit 1 Cycle 2. NRC approval of the LTAs was documented in WBN, Unit 1 License Amendment 8 (Reference 2).
WBN, Unit 1 License Amendment 40 (Referenc e 3) approved the irradiation of up to 2,304 TPBARs in WBN, Unit 1. The exact number of TPBARs to be irradiated are identified in the safety evaluation performed by Westinghouse for each reload core and noted in the Core Operating Limits Report (COLR) for each fuel cycle.
 
Based on issues related to the Reactor Coolant System (RCS) boron concentration, the TVA letter of August 18, 2003, revised the WBN, Unit 1 LAR dated May 30, 2003 and limited the maximum number of TPBARs to be irradiated to 240 in WBN, Unit 1 Cycle 6. This restriction was approved by the NRC in WBN, Unit 1 License Amendment 48 (Reference 4). Design changes made to the TPBARs scheduled for Cycle 9 supported a request to increase the maximum number of TPBARs to be irradiated to 400. This increase was approved with the issuance of WBN, Unit 1 License Amendment 67 (Reference 5). The number of TPBARs irradiated in Cycle 9 was 368. TVA reduced the number of TPBARs irradiated in Cycle 10  to 240 after discovering that the design changes deployed in Cycle 9 were ineffective. WBN, Unit 1 License Amendment 77 (Reference 1) was issued allowing TVA  to increase the maximum number of TPBARs to be irradiated to 704. Because analysis showed consistent tritium releases due to TPBAR permeation in Cycles 6 through 9, the number of TPBARs irradiated in Cycles 11 and 12 were increased to 544. Cycle 13 (current operating cycle) and Cycle 14 (next operating cycle) will irradiate the current TS limit of 704 TPBARs.
As described in this LAR, TVA is now requesting approval to revise the maximum number of TPBARs that can be irradiated in any operating cycle to 1,792. The number of TPBARs to be irradiated in any given operating cycle will be evaluated in the reload safety evaluation and documented in the COLR. The number of TPBARs will not exceed 1,792.
 
The following is a general discussion of how core parameters including TPBARs affect soluble boron worth and the effect on post-LOCA subcriticality margin. The general design requirements for the cold leg accumulators (CLAs) and RWST are also provided.
Page E1-4 of 18 The soluble boron in the CLAs and RWST provides negative reactivity to maintain subcriticality following a LOCA. For a given core design, the boron concentration required to achieve post-LOCA subcriticality is a function of several variables, including global core reactivity and boron worth. The global core reactivity is determined by the cycle energy and the detailed core design. For example, the combination of a larger cycle energy and a smaller burnable absorber inventory would lead to a larger global core reactivity and, therefore, higher CLA and RWST minimum boron concentrations to ensure post-LOCA subcriticality.
The boron worth is dependent upon the total neutron absorption in the core, which is also determined by the detailed core design. When large amounts of neutron absorbers
 
are used in the core design (as is the case with large numbers of TPBARs), there is competition for thermal neutrons among all the absorbers which result in hardening of the thermal neutron spectrum (i.e., a shift towards higher neutron energy). As a consequence, the negative worth of each absorber, including RCS boron worth, decreases. The positive reactivity insertion due to the cooldown from hot full power to cold conditions following a LOCA must be overcome by boric acid supplied to the reactor by the ECCS to maintain subcriticality.
The minimum boron requirement for the CLA ensures that the reactor core will remain subcritical during the reflood and post-LOCA recirculation phase based upon the CLAs' contribution to the post-LOCA sump mixture concentration. The functions and design of the CLAs are found in Section 6.3 of the WBN, Unit 1 Updated Final Safety Analysis Report (UFSAR). The minimum boron requirement for the RWST ensures that sufficient negative reactivity is injected into the core to counteract any positive increase in reactivity caused by reactor coolant system cool down. The RWST serves several purposes in addition to the injection of borated water during accident conditions. 
 
The CLAs are required to be operable in Modes 1, 2, and 3 and the RWST in Modes 1, 2, 3, and 4. WBN, Unit 1 SR 3.5.1.2 and SR 3.5.4.2 associated with these functions specify requirements for borated water volume. TS 3.5.1 specifies requirements for isolation valves and nitrogen cover-pressure for the CLAs and TS 3.5.4 specifies requirements for RWST temperature. These limitations support the ability of the CLAs and RWST to replace water to keep the core cooled and to ensure that sufficient boron is available to maintain the reactor in a subcritical condition during postulated accident conditions. The CLAs are passive devices that inject automatically when the reactor coolant system pressure drops below the accumulator's cover-pressure. The RWST provides borated water to the ECCS pumps for injection into the reactor. Three different sets of pumps are utilized to accommodate different size breaks in the reactor coolant
 
system. The RWST also provides water to the containment spray system to control containment pressure during high energy line break accidents. When the injection of the RWST volume has been completed, the pumps are realigned to the containment sump to continue the core cooling and containment pressure control functions.
 
Section 4.1 of this enclosure provides the post-LOCA subcriticality evaluation for a representative core design with 1,792 TPBARs using the current RWST and CLA boron concentrations, which are not changed by this request. This analysis considers the whole range of break sizes up to and including a double-ended guillotine rupture of the Page E1-5 of 18 main coolant loop piping. Additionally, the analysis takes credit for the isolation of the potential unborated dilution source that would have entered the containment at a maximum rate of 40 gallons per minute (gpm), and a conservative lithium leaching assumption for TPBARs assumed to fail.
 
Section 4.2 of this enclosure summarizes the projected tritium release rate due to permeation. The radiological and environmental impacts from irradiated TPBARs are evaluated in Enclosure 2. The projected tritium release rate is based on releases estimated from Cycles 6 through 12 reactor coolant data. This evaluation is an update of the information provided to support WBN, Unit 1 License Amendment 40 (Reference 6).
 
4.1 Post-LOCA Subcriticality Evaluation WBN, Unit 1 License Amendment 77 increased the maximum TPBAR inventory that TVA is authorized to place in WBN, Unit 1 from 400 to 704 TPBARs. The LAR supporting WBN, Unit 1 License Amendment 77 included a post-LOCA subcriticality evaluation for a representative core design with 704 TPBARs to demonstrate subcriticality assuming the current RWST and CLA minimum boron concentrations (3100 parts per million (ppm) and 3000 ppm, respectively).
 
In a similar fashion, to support the increase in the maximum TPBAR inventory to 1,792 TPBARs, a representative core design has been developed that contains 1,792 TPBARs. Post-LOCA subcriticality analyses were performed for this core design using the same codes and methods used in the WBN, Unit 1 License Amendment 77 analysis and using the same RWST and CLA minimum boron concentrations. Control rod insertion was not credited, consistent with current methodology. 
 
The 1,792 TPBAR core design is a hypothetical core design that is representative of current and future WBN, Unit 1 core designs. The core design model was developed using the NRC-approved ANC-L version 8.7.11 (Reference 7), and PHOENIX-L version 8.7.0 (Reference 8) codes. This hypothetical core design generates a cycle energy of 501 Effective Full Power Days using a total of 92 feed assemblies and incorporating 14,912 integral fuel burnable absorber (IFBA) rods and 1,792 TPBARs. 
 
Westinghouse benchmarks lattice calculations with a range of IFBA loadings to higher order codes, which have been approved in References 7 and 8. Good agreement between the higher order code and the lattice code being benchmarked, in addition to a large experience base of diverse core configurations, provides confidence that the lattice modelling capability will remain acceptable as the amount of IFBA and TPBAR loading is increased. TVA is mitigating the risk associated with moving beyond the operating experience base for the number of IFBA and TPBARs by limiting the increase to approximately 400 TPBARs per cycle for the initial transition reloads. Because the minimum number of IFBA rods needed to meet design goals and safety analysis checks are used each cycle, the rate of increase in IFBA loading will be limited as the experience base is expanded. Routine operating cycle surveillance will demonstrate whether the predicted reactor operating characteristics remain acceptable.
A large number of IFBA rods were incorporated into the core design in order to reduce the critical soluble boron concentration. Lowering the required initial RCS boron concentration to maintain criticality in turn maximizes the differential boron worth of the Page E1-6 of 18 core. Therefore, the post-LOCA injection of highly borated water sources, such as the RWST and the CLAs, will have a larger effect on ensuring enough negative reactivity is inserted to maintain subcriticality.
Post-LOCA subcriticality evaluations were performed for the same scenarios as described in WBN, Unit 1 License Amendment 77. Specifically, the post-LOCA long term cooling subcriticality evaluation considered two scenarios: (1) the hot leg break scenario and (2) the cold leg break scenario.
 
4.1.1 Hot Leg Break Scenario
 
In the hot leg break scenario, TPBAR failure is not expected due to the low temperatures of the fuel and TPBARs. Therefore, the assumptions for evaluating this scenario are as follows:  a) no TPBAR failures b) no xenon in the cold critical boron calculation c) no control rod insertion d) cold conditions (50&deg;F to 212&deg;F) e) a pre-condition of peak xenon to minimize the RCS boron concentration f) most reactive time in life Because the TPBARs remain intact, the hot l eg break scenario is less limiting than the cold leg break scenario. 
 
4.1.2 Cold Leg Break Scenario
 
In the cold leg break scenario, TPBAR failure is conservatively assumed to occur. The key assumptions for this scenario are:
 
a) a pre-condition of peak xenon to minimize the RCS boron concentration b) cold conditions (50&deg;F to 212&deg;F) c) TPBAR failure for all TPBARs with 3% lithium (Li)-6 leaching instantaneously for the first day and a maximum of 50% Li-6 leaching thereafter along with a loss of 12 inches of lithium aluminate (LiAlO2) pellets (a change from WBN, Unit 1
 
License Amendment 77) d) an instantaneous loss of helium (He)-3 inventory e) no control rod insertion f) no credit for void feedback g) sump dilution at the time of hot leg switchover (HLSO) h) a conservative xenon credit at the time of HLSO (3 hours) i) most reactive time in life
 
Page E1-7 of 18 The lithium leach rate assumption for the cold leg break scenario is a change from WBN, Unit 1 License Amendment 77. The simplified assumption of 50% TPBAR lithium leaching at time of HLSO was modified to use a time dependent leaching rate of 3% for the first day and a maximum of 50% thereafter. In previous WBN, Unit 1 License Amendment submittals, the TPBAR leaching assumptions were described as very conservative, because leaching of the TPBARs is not instantaneous. The expected leaching rate was stated in those submittals as 3% per day. 
 
Pacific Northwest National Laboratory (PNNL) conducted leach tests with irradiated pellets in TPBAR test rod segments at a post-LOCA temperature of 120&deg;C. These tests verified that pellet leach rates were less than 3% per day for the first 14 days after a TPBAR breach. In addition to the 120&deg;C data, earlier leach tests results were available for bare pellets at 93&deg;C for periods of 60 days and TPBAR test rod segments at 73&deg;C and 93&deg;C for periods of eight days. This additional data was combined with the 120&deg;C, 14-day data to support a conservative extrapolation of leach results to longer time periods. These extrapolations were used to support conclusions about maximum lithium leaching at 93&deg;C for periods up to 120 days. 
 
The cold leg break scenario also differs from the hot leg break scenario due to the assumption of TPBAR failure and the potential for sump dilution. At HLSO, the TPBAR failure assumption of an instantaneous loss of 3% lithium inventory is conservative because leaching of the TPBARs is not instantaneous. The bounding leaching rate is 3% per day; therefore, some value less than 3% of the lithium would have leached at the time of HLSO (3 hours). For the cold leg break, the limiting time is at HLSO when the diluted sump water is conservatively assumed to displace the highly borated water in the reactor vessel without mixing. A long term subcriticality assessment with no xenon is also performed for the cold leg break scenario, but it is not limiting due to the conservative assumptions employed in the HLSO assessment.
 
In the evaluation of the 1,792 TPBAR core design, cycle burnups up to 10,000 megawatt-days per metric ton uranium (MWD/MTU) were considered. Post-LOCA subcriticality margin is limiting around the most reactive time in life, so that cycle burnups beyond 10,000 MWD/MTU are non-limiting.
 
The sump boron concentration used in the evaluation is calculated in a bounding fashion for several different times after event initiation and assumes the minimum RWST, accumulator, and containment ice boron concentrations permitted by the plant TSs.
Also, the fluid masses assumed in the calculation are chosen in a conservative fashion.
For example, minimum RWST, ice mass, and accumulator fluid masses are assumed and a maximum RCS fluid mass is assumed (because the RCS, due to its low boron concentration, represents a dilution source). Because the RCS boron concentration varies with cycle burnup, the sump boron concentration is a function of RCS boron concentration. In the post-LOCA subcriticality methodology, the RCS boron employed is the hot full power (HFP) critical boron concentration assuming peak xenon at the burnup of interest. The conservative assumption of peak xenon has the effect of minimizing the RCS concentration which, in turn, conservatively reduces the sump boron concentration. 
 
Page E1-8 of 18 The sump boron concentration curves are maintained as key safety parameters in the reload safety evaluation process. Three sump boron curves are generated corresponding to three different times following the break: (1) at initiation of cold leg recirculation, (2) at HLSO, and (3) at long term cooling. These sump boron curves account for the removal of an unborated dilution source that would enter the containment at a maximum rate of 40 gpm and would be isolated within 16 hours after the break, as described in WBN, Unit 1 License Amendment 48 (Reference 4) and maintained in WBN, Unit 1 License Amendments 67 (Reference 5) and 77 (Reference 1). The manual actions associated with isolating these dilution pathways within 16 hours were previously reviewed and approved by the NRC in WBN, Unit 1 License Amendment 51 (Reference 9).
 
In order to eliminate this unborated dilution source and the associated manual actions, TVA will replace the containment isolation thermal relief check valves on the lower compartment supply lines to the containment for WBN, Unit 1 Component Cooling Water System and Essential Raw Cooling Water (ERCW) System with simple relief valves. The simple relief valves would only open to relieve an overpressure condition. The thermal relief check valves were the pathway for the unborated dilution source affecting the post-LOCA containment sump boron concentration.
TVA has identified the cooling coils in the upper compartment coolers supplied by ERCW as a potential additional unborated dilution source. The upper compartment coolers are not safety-related, Seismic Category I or I(L)a. The ERCW supply
 
penetrations providing cooling water to the upper compartment coolers use check valves as inboard containment isolations valves. Therefore, unborated ERCW could be provided to the containment during a LOCA concurrent with a failure of the associated outboard containment isolation valve. TVA has determined that the potential dilution flow rate from the upper compartment cooler ERCW lines is less than 40 gpm and the current analysis is bounded by the dilution flow rate assumed in the post-LOCA subcriticality evaluations. However, in order to gain shutdown margin in the LOCA analysis supporting this LAR, TVA assumed that this dilution source was eliminated.
TVA will replace the WBN, Unit 1 upper compartment cooler cooling coils with fully qualified cooling coils to ensure ERCW System integrity during design basis events and eliminate this unborated dilution source.
 
Subcriticality evaluations were performed at reflood, HLSO, and long term cooling conditions. The subcriticality evaluation at initiation of cold leg recirculation is non-limiting because the available sump boron concentration at that time is larger than the sump boron concentration assumed at HLSO.
 
The current WBN, Unit 1 ECCS minimum boron concentrations are given in Table 1 below. As discussed above, the RCS boron concentration is minimized through the assumption of peak xenon as the accident pre-condition. The computer code ANC is used to calculate the HFP, peak xenon critical boron concentration at the most reactive time in life. The sump boron, which is specified as a function of the RCS boron, can then be determined using the sump boron curves.
 
Page E1-9 of 18 3,000 3,300 3,100 3,300 To determine the subcriticality margin, critical boron concentrations are calculated at post-LOCA conditions using ANC and assuming no xenon. The coolant conditions are atmospheric pressure and the most reactive temperature between 50&deg;F and 212&deg;F. For the HLSO subcriticality assessment, a conservative xenon credit is taken because HLSO occurs three hours into the transient, at which time a significant xenon inventory would be present in the core. For an HLSO time of three hours, the xenon credit assumed is
 
equivalent to 210 ppm of boron.
 
The subcriticality margin is calculated by subtracting the calculated critical boron concentration from the available sump boron concentration. Tables 2, 3, and 4 give the subcriticality assessments for the hot leg break scenario (long term assessment), the cold leg break long term assessment, and the cold leg break assessment at HLSO for the core design with 1,792 TPBARs. These assessments employ the same key assumptions (except as noted) as in WBN, Unit 1 License Amendment 77 and adhere to the same approved analytical methods.
150 357 2,095 1,538 557 1,000 420 2,103 1,572 531 2,000 508 2,116 1,621 495 3,000 578 2,126 1,661 465 4,000 621 2,132 1,689 443 6,000 644 2,135 1,711 424 8,000 605 2,129 1,697 432 10,000 525 2,118 1,656 462
 
Page E1-10 of 18 150 357 2,095 1,728 367 1,000 420 2,103 1,765 338 2,000 508 2,116 1,819 297 3,000 578 2,126 1,863 263 4,000 621 2,132 1,895 237 6,000 644 2,135 1,923 212 8,000 605 2,129 1,917 212 10,000 525 2,118 1,876 242 150 357 1,675 1,628 210 1,418 257 1,000 420 1,688 1,664 210 1,454 234 2,000 508 1,707 1,716 210 1,506 201 3,000 578 1,722 1,759 210 1,549 173 4,000 621 1,731 1,790 210 1,580 151 6,000 644 1,736 1,817 210 1,607 129 8,000 605 1,728 1,811 210 1,601 127 10,000 525 1,711 1,770 210 1,560 151 From Tables 2, 3, and 4, the most limiting range for each scenario is 6,000 to 8,000 MWD/MTU. Also, as expected, the HLSO assessment is the most limiting scenario with a minimum margin of 127 ppm for this core design. HLSO is limiting due to the conservative assumptions of TPBAR failure and sump dilution with no mixing in the vessel.
 
Page E1-11 of 18
 
====4.1.3 Reflood====
Stage Subcriticality In addition to the above scenarios, subcriticality during reflood was examined for this core model at the most reactive time in life. The reflood stage occurs immediately following the blowdown phase of a large break LOCA, and the core must be shown to remain subcritical prior to RWST injection. During reflood, the boron concentration in the core is dependent upon the initial RCS boron concentration, the RCS water inventory in the bottom of the reactor vessel at the end of the blowdown stage (which in turn is dependent on the relative size of the break), and the CLA boron concentration. For the 1,792 TPBAR core, the smallest effective break size was shown to be limiting because it maximizes the contribution of the lower initial RCS boron concentration. Furthermore, the initial RCS boron concentration was minimized by assuming peak xenon in the pre-LOCA calculation. The limiting boron concentration at the initial reflood was calculated to be 1,915 ppm using a pre-LOCA boron concentration of 644 ppm and a minimum accumulator boron concentration of 3,000 ppm. The results in Table 5 show the available reflood margin in both percent-millirho (pcm) and ppm for different post-LOCA xenon conditions. Standard methods allow for a generic xenon credit of 2,000 pcm which is also presented. Peak Xenon 3,816 573 Equilibrium Xenon 2,956 441 No Xenon 606 89 2,000 pcm Xenon Credit 2,606 387 Control rod insertion and moderator void feedback are not credited. For cold leg breaks, this reflood evaluation is sufficient to confirm subcriticality from the time of reflood until HLSO because the reactor vessel boron increases during this time due to boiling in the core. For hot leg breaks, the long term subcriticality assessment is more limiting than the reflood assessment because no xenon can be assumed in the long term evaluation.
 
In summary, these results confirm that adequate subcriticality margin can be
 
demonstrated for a representative core des ign with 1,792 TPBARs using the current ECCS minimum boron concentrations and current methodology. In the event that subcriticality for a core design under consideration cannot be demonstrated using the current methodology, then either the core design will be modified or a new LAR will be initiated. Post-LOCA subcriticality will continue to be evaluated for each core design as part of the cycle-specific comprehensive reload safety evaluation process (Reference 10).
 
===4.2 TPBAR===
Tritium Release Rate TVA routinely monitors the tritium in the reactor coolant and estimates tritium releases from TPBARs in order to confirm cycle to cycle consistency and identify anomalous behavior. TVA has seven cycles of experience with the irradiation of TPBARs. The estimated TPBAR tritium releases from Cycle 6 through Cycle 12 are provided in Figure E1-1. TPBAR release estimates for Cycle 6 through Cycle 12 demonstrate consistent TPBAR performance.
T t h T hese estim a h e NRC, as s a tes have s h s hown in Fi g Pag e h own consis t g ure 2. e E1-12 of 1 8t ency with t h 8 h e total site t t ritium relea ss es reporte d d to T e a b T E U T 1 T
T he agreem e stimated rel ere due to th eased on a 9 The radiologi .
Unit 1 Licens T VA will cont0 CFR Part  T he TPBAR s Secti o Secti o Secti o Secti o Secti o Secti o e nt between e ases to th e e discrete n a 0% confide n cal and env i This evalu a e Amendm e inue to mon 20 and 10 C s are descri b on 11.1, So u on 11.2, Liq u on 11.3, Ga s o n 11A.5, T r on 15.3.5, W on 15.5, En v Pag e the estimat e e RCS. The a ture of effl u n ce interval.
i ronmental i m a tion is an u p e nt 40 (Refe r itor the tritiu CFR Part 50  b ed in WBN, u rce Terms u id Waste S y s eous Wast e r itium Contr o W aste Gas D vironmental C e E1-13 of 1 8 e d and repo differences u ent dischar g m pacts fro m p date of the rence 6). m released Appendix I Unit 1 UFS A ystems e Systems o l ecay Tank R Consequen c 8 rted values between e s g es. The e r m irradiated T information from the sit e requiremen t
A R Chapter s R upture ces of Accid provides co n s timates an d r ror bars for T PBARs ar e p r ovided t o e to ensure t t s are met.
s 11 and 15 ents n fidence in t d reported v a estimates a r e evaluated i o support W B t hat the . t he a lues r e n B N, Page E1-14 of 18 For these sections, the principal review performed by NRC is documented in the Safety Evaluation Report (SER), NUREG-0847, dated June 1982. The assessment of these functions with respect to TPBAR irradiation is documented in the safety evaluation for WBN, Unit 1 License Amendment 40 (Reference 3). 
 
The proposed amendment, which is identical in scope to WBN, Unit 1 License Amendment 77, will increase the limit on the number of TPBARs that can be irradiated in the WBN core to 1,792. The current CLA and RWST boron concentration requirements in SRs 3.5.1.4, "Accumulators," and 3.5.4.3, "Refueling Water Storage Tank (RWST)," provide adequate protection for 1,792 TPBARs. Analyses show that the existing boron concentrations will prevent a recriticality event for a core with 1,792 TPBARs during postulated accidents and will not adversely affect compliance with the requirements for emergency core cooling systems in 10 CFR 50.46 or 10 CFR Part 50, Appendix K. The ability of the current CLA and RWST boron concentration requirements to ensure subcriticality during postulated accidents will continue to be assessed each cycle as part of the reload safety evaluation process. 
 
The projected tritium release rate and radiological and environmental impacts from irradiated TPBARs was originally evaluated for WBN, Unit 1 License Amendment 40 (Reference 6). The radiological and environmental information was updated for the proposed license amendment to address the effects of tritium permeation from a reactor core with up to 1,792 TPBARs and shown to meet all regulatory requirements.
 
TVA has determined that this request is similar to the following WBN, Unit 1. License Amendments, which have been approved by the NRC:
: 1. NRC letter to TVA dated September 23, 2002, "Watts Bar Nuclear Plant, Unit 1 - Issuance of Amendment to Irradiate Up to 2304 Tritium-Producing Burnable Absorber Rods in the Reactor Core (TAC No. MB1884)," (ADAMS Accession No.
ML022540925).
: 2. NRC letter to TVA dated October 8, 2003, "Watts Bar Nuclear Plant, Unit 1 - Issuance of Amendment Regarding Revision of Boron Requirements for Cold Leg Accumulators and Refueling Water Storage Tank (TAC No. MB9480)," (ADAMS Accession No. ML032880062).
: 3. NRC letter to TVA dated January 18, 2008, "Watts Bar Nuclear Plant, Unit 1 - Issuance of Amendment Regarding the Maximum Number of Tritium Producing Burnable Assembly Rods in the Reactor Core (TAC No. MD5430)," (ADAMS Accession No. ML073520546).
: 4. NRC letter to TVA dated May 4, 2009, "Watts Bar Nuclear Plant, Unit 1 - Issuance of Amendment Regarding the Maximum Number of Tritium Producing Burnable Assembly Rods in the Reactor Core (TAC No. MD9396)," (ADAMS Accession No.
ML090920506).
 
Page E1-15 of 18 The Tennessee Valley Authority (TVA) proposes to revise the current licensing basis of Facility Operating License No. NFP-90 for the Watts Bar Nuclear Plant (WBN), Unit 1 by revising the WBN, Unit 1 Technical Specifications (TS) 4.2.1, "Fuel Assemblies," to revise the maximum number of tritium producing burnable absorber rods (TPBARs) in the core. This proposed change will support a planned increase in the TPBAR inventory in the WBN, Unit 1 reactor core to support national security needs.
 
The proposed TS change will also revise TS 3.5.1, "Accumulators," Surveillance Requirement (SR) 3.5.1.4 and TS 3.5.4, "Refueling Water Storage Tank (RWST),"
SR 3.5.4.3 to delete outdated information related to the tritium production program.
 
TVA has concluded that the changes to WBN, Unit 1 TS 4.2.1, SR 3.5.1.4, and SR 3.5.4.3 do not involve a significant hazards consideration. TVA's conclusion is based on its evaluation in accordance with 10 CFR 50.91(a)(1) of the three standards set forth in 10 CFR 50.92, "Issuance of Amendment," as discussed below:
Response:  No.
The proposed change to TS 4.2.1 revises the maximum number of TPBARs in the core. The safety analyses demonstrated sufficient reactivity control after a postulated loss of coolant accident (LOCA) to maintain the reactor core subcritical. The current boron concentration has been demonstrated to maintain the required accident mitigation safety function for the Cold Leg Accumulators (CLAs) and Refueling Water Storage Tank (RWST) with the higher number of TPBARs. This conclusion will be verified for each core that contains TPBARs as part of the normal reload analysis. The TPBARs are not potential sources for accident generation and the modification of the number of TPBARs will not increase the potential for an accident. Therefore, the possibility of an accident is not increased by the proposed changes. Because the reactor core remains subcritical after a postulated LOCA, the consequences of an accident are not increased by the proposed changes.
The proposed change to TS SRs 3.5.1.4 and 3.5.4.3 to delete outdated information related to the tritium production program is administrative in nature.
 
The modifications to eliminate potential sources of post-LOCA sump dilution described in this amendment request restore the original design basis of the plant. These modifications eliminate operator actions credited to isolate the unborated water lines in the event of a design basis accident. The modifications eliminate the potential for human error associated with the required manual actions.
Based on the above discussions, the proposed changes do not involve an increase in the probability or consequences of an accident previously evaluated.
 
Page E1-16 of 18 Response: No. The proposed change to TS 4.2.1 revises the maximum number of TPBARs in the core. The boron concentrations for accident mitigation functions of the CLAs and RWST remain unchanged. The modifications to eliminate potential sources of post-LOCA sump dilution described in this amendment request restore the original design basis of the plant. These modifications eliminate operator actions credited to isolate the unborated water lines in the event of a design basis accident. The modifications eliminate the potential for human error associated with the required manual actions. Because the TPBARs are manufactured to the same quality standards as the other core components, the possibility of a new or different kind of an accident is not created.
 
The proposed change to TS SRs 3.5.1.4 and 3.5.4.3 to delete outdated information related to the tritium production program is administrative in nature. 
 
Therefore, the proposed changes do not create the possibility of a new or different kind of accident from any accident previously evaluated.
 
Response: No. The proposed change to TS 4.2.1 revises the maximum number of TPBARs in the core. The proposed change does not alter any setpoints utilized for the actuation of accident mitigation system or control functions. The proposed number of TPBARs, in conjunction with the current boron concentration values, has been demonstrated to provide an adequate level of reactivity control for accident mitigation. This conclusion will be verified for each core that contains TPBARs as part of the normal reload analysis. Therefore, the proposed change will not involve a significant reduction in a margin of safety. 
 
The proposed change to TS SRs 3.5.1.4 and 3.5.4.3 to delete outdated information related to the tritium production program is administrative in nature.
 
The modifications to eliminate potential sources of post-LOCA sump dilution described in this amendment request restore the original design basis of the plant. These modifications eliminate operator actions credited to isolate the unborated water lines in the event of a design basis accident. The modifications eliminate the potential for human error associated with the required manual
 
actions
 
Accordingly, the proposed changes do not involve a significant reduction in a margin of safety.
 
Page E1-17 of 18 In conclusion, based on the considerations discussed above, (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the license amendment will not be inimical to the common defense and security or to the health and safety of the public.
The environmental impacts of producing tritium in the Tennessee Valley Authority's (TVA's) Watts Bar Nuclear Plant (WBN), Unit 1 were assessed in a 1999 "Final Environmental Impact Statement (EIS) for the Production of Tritium in a Commercial Light Water Reactors" (DOE/EIS0288) prepared by the Department of Energy (DOE). TVA was a cooperating agency in the preparation of this EIS. In accordance with 40 CFR 1506.3(c) of the Council on Environmental Quality regulations, TVA independently reviewed the EIS prepared by DOE, found it to be adequate, and adopted the EIS.
TVA's "Record of Decision and Adoption of the Final Environmental Impact Statement for the Production of Tritium in a Commercial Light Water Reactor" was published in the Federal Register at 65 FR 26259 (May 5, 2000). 
 
The DOE has prepared a Draft Supplemental Environmental Impact Statement (SEIS) to update the environmental analyses in DOE's 1999 EIS for the Production of Tritium in a Commercial Light Water Reactor.1  The SEIS is being prepared to address impacts associated with the higher permeation rate for tritium from the TPBARs and DOE's revised estimate of the maximum number of TPBARs necessary to support the current tritium supply requirements. The DOE notes that although the TPBAR captures 99.96%
of the tritium produced, it is still absorbed at a rate lower than was originally analyzed.
The results of the analyses presented in the SEIS indicate there would be no significant
 
increase in radiation exposure associated with TPBAR irradiation for facility workers or the public. For all analyzed alternatives, estimated radiation exposures would remain well below regulatory limits. TVA is a cooperating agency in the preparation of this SEIS. In accordance with 40 CFR 1506.3(c) of the Council on Environmental Quality regulations, TVA is independently reviewing the SEIS prepared by DOE and plans to adopt the SEIS prior to irradiating more TPBARs than currently authorized by NRC. 
 
TVA also provided information to NRC regarding the environmental impacts associated with tritium production from as many as 2,304 TPBARs to support WBN, Unit 1 License Amendment 40 (Reference 6). NRC used this information in their Environmental Assessment and Finding of No Significant Impact for WBN, Unit 1 License Amendment 40 (Reference 11). Enclosure 2 to this letter provides an update to this information. 
 
Based on the 1999 EIS prepared by the DOE, the information provided to NRC (Reference 6) for WBN, Unit 1 License Amendment 40 and the corresponding NRC Environmental Assessment and Finding of No Significant Impact, the draft SEIS prepared by the DOE, and the updated evaluation information provided for this proposed 1  See http://nnsa.energy.gov/aboutus/ouroperations/generalcounsel/nepaoverview/nepa/tritiumseis for more information on the SEIS being prepared by the DOE.
Page E1-18 of 18 amendment in Enclosure 2, the proposed amendment does not involve (i) a significant hazards consideration, (ii) a significant change in the types or significant increase in the amounts of any effluents that may be released offsite, or (iii) a significant increase in individual or cumulative occupational radiation exposure. Accordingly, the proposed amendment meets the eligibility criterion for categorical exclusion set forth in 10 CFR 51.22(c)(9). Therefore, pursuant to 10 CFR 51.22(b), NRC will not need to prepare an environmental impact statement or environmental assessment in connection with the proposed amendment. 1. NRC letter to TVA dated May 4, 2009, "Watts Bar Nuclear Plant, Unit 1 - Issuance of Amendment Regarding the Maximum Number of Tritium Producing Burnable Assembly Rods in the Reactor Core (TAC No. MD9396)," (ADAMS Accession No. ML090920506). 2. NRC letter to TVA dated September 15, 1997, "Issuance of Amendment on Tritium Producing Burnable Absorber Lead Test Assemblies (TAC No. M98615)," (ADAMS Accession No. ML020780128). 3. NRC letter to TVA dated September 23, 2002, "Watts Bar Nuclear Plant, Unit 1 - Issuance of Amendment to Irradiate Up to 2304 Tritium-Producing Burnable Absorber Rods in the Reactor Core (TAC No. MB1884)," (ADAMS Accession No. ML022540925). 4. NRC letter to TVA dated October 8, 2003, "Watts Bar Nuclear Plant, Unit 1 - Issuance of Amendment Regarding Revision of Boron Requirements for Cold Leg Accumulators and Refueling Water Storage Tank (TAC No. MB9480)," (ADAMS Accession No. ML032880062). 5. NRC letter to TVA dated January 18, 2008, "Watts Bar Nuclear Plant, Unit 1 - Issuance of Amendment Regarding the Maximum Number of Tritium Producing Burnable Assembly Rods in the Reactor Core (TAC No. MD5430)," (ADAMS Accession No. ML073520546). 6. TVA letter to NRC dated May 23, 2002, "Watts Bar Nuclear Plant - Request for Additional Information (RAI) Regarding Radiological Impact (TAC NO. MB1884)," (ADAMS Accession No. ML021490139). 7. WCAP-10965-P-A, "ANC: A Westinghouse Advanced Nodal Computer Code," September 1986. 8. WCAP-11596-P-A, "Qualification of the PHOENIX-P/ANC Nuclear Design System for Pressurized Water Reactor Cores," June 1988. 9. NRC letter to TVA dated March 29, 2004, "Watts Bar Nuclear Plant, Unit 1 - Issuance of An Amendment to Revise the Updated Final Safety Analysis Report Failure Modes and Effects Analysis - Use of Operator Action (TAC No. MB8102),"
(ADAMS Accession No. ML040900172). 10. WCAP-9272-P-A, "Westinghouse Reload Safety Evaluation Methodology," July 1985. 11. NRC letter to TVA dated August 20, 2002, "Watts Bar Nuclear Plant, Unit 1 - Environmental Assessment and Finding of No Significant Impact for Incore Irradiation Services for the U.S. Department of Energy's Tritium Production Program (TAC No. MB1884)," (ADAMS Accession No. ML022320905). 
: 1. Affected TS Pages TS 3.5-2  TS 3.5-10  TS 4.0-1 SURVEILLANCE REQUIREMENTS SURVEILLANCE FREQUENCY  SR  3.5.1.1 Verify each accumulator isolation valve is fully open.
12 hours  SR  3.5.1.2 Verify borated water volume in each accumulator is    7630 gallons and  8000 gallons.
12 hours  SR  3.5.1.3 Verify nitrogen cover pressure in each accumulator is  610 psig and  660 psig  12 hours  SR  3.5.1.4
--------------------------------NOTE-------------------------------
The number of TPBARs in the reactor core is contained in the Core Operating Limits Report (COLR) for each operating cycle.
  ------------------------------------------------------------------------
Verify boron concentration in each accumulator is as provided below depending on the number of tritium producing burnable absorber rods (TPBARs) installed in the reactor core for this operating cycle. Number of TPBARs Boron Concentration Ranges 0-704    31 days  AND 
-------NOTE -----------
Only required to be performed for affected accumulators.
---------------------------
Once within 6 hours after each solution volume increase of  75 gallons, that is not the result of addition from the refueling water storage tank.
  (continued)
 
SURVEILLANCE REQUIREMENTS SURVEILLANCE FREQUENCY  SR  3.5.4.1
------------------------------NOTE----------------------------------Only required to be performed when ambient air temperature is <
60&deg;F or > 105&deg;F.  ------------------------------------------------------------------------
Verify RWST borated water temperature is 60&deg;F and  105&deg;F.   
 
24 hours  SR  3.5.4.2 Verify RWST borated water volume is 370,000 gallons.
7 days  SR  3.5.4.3
-----------------------------------NOTE----------------------------------
The number of TPBARs in the reactor core is contained in the Core Operating Limits Report (COLR) for each operating cycle.
  -----------------------------------------------------------------------------
Verify boron concentration in the RWST is  3100 ppm and  3300 ppm. Number of TPBARs Boron Concentration Ranges 0-704 
 
7 days   
 
===4.0 DESIGN===
FEATURES 4.1 Site  4.1.1 Site and Exclusion Area Boundaries The site and exclusion area boundaries shall be as shown in Figure 4.1-1. 4.1.2 Low Population Zone (LPZ)
 
The LPZ shall be as shown in Figure 4.1-2 (within the 3
-mile circle).
 
===4.2 Reactor===
Core 4.2.1 Fuel Assemblies The reactor shall contain 193 fuel assemblies. Each assembly shall consist of a matrix of Zircalloy or Zirlo fuel rods with an initial composition of natural or slightly enriched uranium dioxide (UO
: 2) as fuel material. Limited substitutions of zirconium alloy or stainless steel filler rods for fuel rods, in accordance with approved applications of fuel rod configurations, may be used. Fuel assemblies shall be limited to those fuel designs that have been analyzed with applicable NRC staff approved codes and methods and shown by tests or analyses to comply with all fuel safety design bases. A limited number of lead test assemblies that have not completed representative testing may be placed in nonlimiting core regions. For Unit 1 Watts Bar is authorized to place a maximum of 704    Tritium Producing Burnable Absorber Rods into the reactor in an operating cycle.
 
====4.2.2 Control====
Rod Assemblies
 
The reactor core shall contain 57 control rod assemblies. The control material shall be either silver
-indium-cadmium or boron carbide with silver indium cadmium tips as approved by the NRC.
1792 1.Affected TS P agesTS 3.5-2TS 3.5-10TS 4.0-1 SURVEILLANCE REQUIREMENTS SURVEILLANCE FREQUENCY SR  3.5.1.1 Verify each accumulator isolation valve is fully open.
12 hours SR  3.5.1.2 Verify borated water volume in each accumulator is  7630 gallons and  8000 gallons.
12 hours SR  3.5.1.3 Verify nitrogen cover pressure in each accumulator is 610 psig and  660 psig 12 hours SR  3.5.1.4 Verify boron concentration in each accumulator is  3000 ppm and  3300 ppm. 31 days AND -------NOTE -----------
Only required to be performed for affected accumulators.
---------------------------
Once within 6 hours after each solution volume increase of  75 gallons, that is not the result of addition from the refueling water storage tank.
(continued)
 
SURVEILLANCE REQUIREMENTS SURVEILLANCE FREQUENCY SR  3.5.4.1
------------------------------NOTE----------------------------------Only required to be performed when ambient air temperature is <
60&deg;F or > 105&deg;F.  ------------------------------------------------------------------------Verify RWST borated water temperature is 60&deg;F and  105&deg;F. 24 hours SR  3.5.4.2 Verify RWST borated water volume is  370,000 gallons.
7 days SR  3.5.4.3 Verify boron concentration in the RWST is  3100 ppm and  3300 ppm 7 days 
 
===4.0 DESIGN===
FEATURES 4.1 Site 4.1.1 Site and Exclusion Area Boundaries The site and exclusion area boundaries shall be as shown in Figure 4.1-1. 4.1.2 Low Population Zone (LPZ)
The LPZ shall be as shown in Figure 4.1-2 (within the 3
-mile circle).
 
===4.2 Reactor===
Core 4.2.1 Fuel Assemblies The reactor shall contain 193 fuel assemblies. Each assembly shall consist of a matrix of Zircalloy or Zirlo fuel rods with an initial composition of natural or slightly enriched uranium dioxide (UO
: 2) as fuel material. Limited substitutions of zirconium alloy or stainless steel filler rods for fuel rods, in accordance with approved applications of fuel rod configurations, may be used. Fuel assemblies shall be limited to those fuel designs that have been analyzed with applicable NRC staff approved codes and methods and shown by tests or analyses to comply with all fuel safety design bases. A limited number of lead test assemblies that have not completed representative testing may be placed in nonlimiting core regions. For Unit 1 Watts Bar is authorized to place a maximum of 1792 Tritium Producing Burnable Absorber Rods into the reactor in an operating cycle.
 
====4.2.2 Control====
Rod Assemblies The reactor core shall contain 57 control rod assemblies. The control material shall be either silver
-indium-cadmium or boron carbide with silver indium cadmium tips as approved by the NRC.
: 1. Affected TS Bases Pages TS 3.5-26  TS 3.5-27 APPLICABLE  volume. The deliverable volume limit is set by the LOCA and containment SAFETY ANALYSES analyses. For the RWST, the deliverable volume is different from the total (continued)  volume contained since, due to the design of the tank, more water can be contained than can be delivered. The minimum boron concentration is an explicit assumption in the main steam line break (MSLB) analysis to ensure the required shutdown capability. The maximum boron concentration is an explicit assumption in the inadvertent ECCS actuation analysis, although it is typically a nonlimiting event and the results are very insensitive to boron concentrations. The maximum temperature ensures that the amount of cooling provided from the RWST during the heatup phase of a feedline break is consistent with safety analysis assumptions; the minimum is an assumption in both the MSLB and inadvertent ECCS actuation analyses, although the inadvertent ECCS actuation event is typically nonlimiting.
 
The MSLB analysis has considered a delay associated with the interlock between the VCT and RWST isolation valves, and the results show that the departure from nucleate boiling design basis is met. The delay has been established as 27 seconds, with offsite power available, or 37 seconds without offsite power.
Technical Specification Surveillance Requirements 3.5.1.4, "Accumulators," and 3.5.4.3, "RWST," match boron concentrations to the number of tritium producing burnable absorbers rods (TPBARs) installed in the reactor core. Watts Bar is authorized to place a maximum of 704 TPBARs into the reactor in an operating cycle. Generally, TPBARs act as burnable absorber rods normally found in similar reactor core designs. However, unlike burnable absorber rods which lose their poison effects over the life of the cycle, some residual effect remains in the TPBARs at the end of the cycle. When larger amounts of excess neutron poisons (as in the case with larger loads of TPBARs) are added to a core, there is competition for neutrons from all the poison and the negative worth of each poison (including the reactor coolant system (RCS) boron) decreases. The positive reactivity insertion due to the negative moderator coefficient that occurs during the cooldown from hot full power to cold conditions following a loss of coolant accident (LOCA) must be overcome by RCS boron. Because the RCS boron is worth less, it takes a higher concentration to maintain subcriticality.
For a large break LOCA Analysis, the minimum water volume limit of 370,000 gallons and the minimum boron concentration limit is used to compute the post LOCA sump boron concentration necessary to assure subcriticality. This APPLICABLE  minimum value depends on the number of TPBARs in the core as specified in SAFETY ANALYSES the Core Operating Limits Report (COLR) for each operating cycle.
The large (continued)  break LOCA is the limiting case since the safety analysis assumes least negative reactivity insertion.
The upper limit on boron concentration of 3300 ppm is used to determine the maximum allowable time to switch to hot leg recirculation following a LOCA. The purpose of switching from cold leg to hot leg injection is to avoid boron precipitation in the core following the accident.
 
In the ECCS analysis, the containment spray temperature is assumed to be equal to the RWST lower temperature limit of 60&deg;F. If the lower temperature limit is violated, the containment spray further reduces containment pressure, which decreases the rate at which steam can be vented out the break and increases peak clad temperature. The acceptable temperature range of 60&deg;F to 105&deg;F is assumed in the large break LOCA analysis, and the small break analysis value bounds the upper temperature limit of 105&deg;F. The upper temperature limit of 105&deg;F is also used in the containment OPERABILITY analysis. Exceeding the upper temperature limit will result in a higher peak clad temperature, because there is less heat transfer from the core to the injected water following a LOCA and higher containment pressures due to reduced containment spray cooling capacity. For the containment response following an MSLB, the lower limit on boron concentration and the upper limit on RWST water temperature are used to maximize the total energy release to containment.
The RWST satisfies Criterion 3 of the NRC Policy Statement.
LCO  The RWST ensures that an adequate supply of borated water is available to cool and depressurize the containment in the event of a Design Basis Accident (DBA), to cool and cover the core in the event of a LOCA, to maintain the reactor subcritical following a DBA, and to ensure adequate level in the containment sump to support ECCS and Containment Spray System pump operation in the recirculation mode.
To be considered OPERABLE, the RWST must meet the water volume, boron concentration, and temperature limits established in the SRs.
 
==Subject:==
Application to Revise Technical Specification 4.2.1 , "Fuel Assemblies," (WBN-TS-15-03)  
 
The Department of Energy (DOE) and the Tennessee Valley Authority (TVA) have agreed to cooperate in a program to produce tritium for the National Security Stockpile by irradiating Tritium Producing Burnable Absorber Rods (TPBARs) at Watts Bar Nuclear (WBN) Unit 1.
The initial environmental impacts of producing tritium at WBN Unit 1 were assessed in a Final Environmental Impact Statement (EIS) for the Production of Tritium in a Commercial Light Water Reactor (DOE/EIS - 0288, March 1999) which was prepared by DOE. TVA was a cooperating agency in the preparation of this EIS, and adopted the EIS in accordance with 40 CFR 1506.30 of the Council on Environmental Quality regulations. TVA's (ROD were published in the Federal Register at 65 Federal Register 26259 (May 5, 2000). In addition to the DOE EIS and TVA's ROD, a Tritium Production Core (TPC) Topical Report (NDP 181, Revision 1) was prepared by DOE to address the safety and licensing issues associated with incorporating TPBARs in a pressurized water reactor (PWR). The Nuclear Regulatory Commission's (NRC) Standard Review Plan (SRP) NUREG
-0800 was used as the basis for evaluating the impact of the TPBARs on a reference plant. The NRC reviewed the TPC Topical Report and issued Safety Evaluation Report (SER) NUREG
-1672 to support plant
-specific licensing of TPBARs in a PWR. TVA letter dated August 20, 2001 1, addressed the interface items described in NUREG
-1672, Section 5.1, and requested authorization to irradiated not more than 2,304 TPBARs in WBN Unit 1. NRC issued a Safety Evaluation (SE) approving WBN Unit 1 License Amendment 40 on September 23, 2002 2, authorizing WBN Unit 1 to irradiate up to a maximum of 2,304 TPBARs in WBN Unit 1. TVA's application for that amendment provided radiological analyses based on 2,304 Curies (Ci)/year release attributable to TPBARs, based on the TVA functional requirement of one Ci/TPBAR/year for 2,304 TPBARs. The SE recognized that for the 2,304 TPC "licensee calculations demonstrated that doses to the public from effluents and the tritium release concentrations will remain below offsite dose calculation manual (ODCM) limits and 10 CFR Part 20 release limits."  The ODCM reflects the plant
-specific, applicable requirements of 10 CFR Part 20 and 10 CFR Part 50, Appendix I. The NRC Environmental Assessment and Finding of No Significant Impact for the 2,304 TPC concluded that The proposed "" TVA notified NRC that TVA had imposed interim administrative limits on the number of TPBARs to be loaded in the WBN, Unit 1 reactor.
3  The interim controls limited the number of TPBARs to be irradiated in any cycle such that the total tritium released into the Reactor Coolant System (RCS) by permeation would remain below the 2,304 Ci value evaluated for WBN Unit 1 License Amendment 40. TVA has maintained the interim administrative limits while higher than expected tritium permeation was investigated.
TVA letter to NRC dated April 25, 2007, included an update on the tritium permeation investigation, including a discussion of the post irradiation examination (PIE) and the Mark 9.2 TPBAR design changes.
4  Based on the PIE and review of the mechanisms associated with tritium transport within the TPBAR, several design changes were made to the TPBARs inserted
 
for Cycle 9. The changes were expected to decrease the tritium permeation and achieve the original tritium permeation goal of less than 1.0 Ci/TPBAR/year. TVA also stated that the effectiveness of the TPBAR design changes would be determined through the monitoring of RCS tritium levels throughout Cycle 9 operation.
TVA Letter to NRC dated December 31, 2008, "Watts Bar Nuclear Plant (WBN) Unit 1 - Revised Technical Specifications Change WBN
-TS-08 Revision to the Maximum Number of TPBARs that Can Be Irradiated in the Reactor Core Per Cycle (TAC No. MD9396)," included an update on the TPBAR tritium release rate through Cycle 8, which showed consistent performance with that observed in Cycle 7.
5  TVA conducted this updated review of the environmental impacts with a particular focus on evaluating the radiological aspects associated with the irradiation of TPBARs at WBN for a 1,900 TPBAR T PC. This review utilizes the updated conservative TPBAR annual release (permeation) rates of 5 tritium Ci/TPBAR/year for the Realistic Basis (i.e., effluent dose calculations) and 10 tritium Ci/TPBAR/year for the Design Basis 7 (i.e., station occupational exposure and radwaste system capability review).
The realistic permeation rate of 5 Ci/TPBAR/y ear is acceptable because it bounds the observed permeation rate. The design basis permeation rate of 10 Ci/TPBAR/y ea r provides an additional factor of two margin and is therefore reasonable, but conservative and bounding. Pacific Northwest National Laboratory (PNNL) 8 has estimated the permeation and uncertainty for cycle 12 TPBARs as end of cycle release for cycle 12 was calculated to be 3.6 +/- 0.6 Ci/TPBAR. The bounding annual tritium release rate for cycle 12, averaged over the last year of the cycle, was calculated to be 3.2 +/- 0.6 Ci/TPBAR/year.
The estimated cumulative tritium permeation per TPBAR for WBN Unit 1 Tritium Production Cycles 6 - 12 are shown on Figure 1.
The Mark 9.2 TPBAR design 9 included significant design changes from the multi
-pencil Production TPBAR design of the prior TPC Cycles.
However, the average annual release rate per M ark 9.2 TPBAR (3.4 +/- 0.8 Ci/TPBAR/year) is similar to that estimated for the multi
-pencil Production Design TPBARs of previous WBN Unit 1 cycles.
When the TPBAR permeation estimates are presented in a calendar year format (Figure 2), corresponding to the NRC monitoring and reporting requirements, the annualized per TPBAR permeation have consistently remained less than 3 Ci/y ear. With the approximate 18-month fuel cycles, portions of multiple (i.e., two) fuel cycles will occur periodically in the same calendar years. 
 
In addition, this review incorporates the experiences and lessons from the previous Tritium Production Fuel Cycles at WBN (Cycles 6 - 12). This review addresses both the onsite and offsite potential radiological impacts of tritium production with 1,792 TPBARs. Updated plant
-specific evaluations (and analyses if required) were performed for WBN using the equations and values given in the Watts Bar Updated Final Safety Analysis Report (UFSAR) and ODCM. The review includes the identification of any significant differences between the updated TPBAR permeation estimates with a 1,900 TPBAR Core (Realistic Basis) and the WBN Unit 1 License Amendment 40 associated with the TPBARs and an assessment for potential impacts. The noted differences are discussed in each section of this review, as appropriate, with the WBN Unit 1 License Amendment 40 values indicated in . When the WBN Unit 1 License Amendment 40 values remain bounding, they are so indicated.
Upon review of the documents and the analyses described above, this review determined that there were no substantial changes, that is, WBN Unit 1 will continue to demonstrate effluent release performance well within the regulatory As Low as Reasonably Achievable (ALARA) public dose guidelines of 10 CFR Part 50 Appendix I and occupational radiation exposure continues to be bounded by the station dose assessment of record10, associated with the radiological impact analyses that were relevant to environmental concerns, nor were there any significant new circumstances or information relevant to environmental concerns which bore on the radiological impacts associated with the tritium production program. The impact of WBN Unit 1 operation with a TPC containing up to  TPBARs (Design Basis) will have a minimal impact on the Radwaste System Design Basis and realistic fission and corrosion product sources and the treatment of these isotopes in liquid and gaseous waste11. The Radwaste System Design Basis tritium sources are estimated to increase the amount of tritium that is discharged annually by a factor of about fourteen. As indicated on, Table 5, "Annual Projected Impact of TPC on Effluent Dose to Maximally Exposed Members of the Public and Total Public Dose," the differences noted in the source terms for TPC operation would not affect the ability of the plant to remain within the applicable regulatory requirements relative to radioactivity in effluents to unrestricted areas (i.e., 10 CFR Part 20), the "as low as is reasonably achievable" criterion (i.e., 10 CFR Part 50 - Appendix I). However, Radwaste System Design Basis tritium sources with TPBARs are expected to increase the total amount of tritium that is generated in the plant by a factor of fourteen (i.e., from about 1,889 curies per year to approximately curies per year).
Updated program controls provide further refinement to the application of the TPBAR permeation performance metric. The permeation performance metric refinements will facilitate the monitoring of TPBAR cycle
-to-cycle performance that will allow TVA and DOE to monitor TPBAR permeation performance as a metric for tracking, trending, and evaluating effectiveness of future design changes and TPBAR performance.
The DOE/NRC recommended RCS tritium control value was 3.5 microcuries/gram (&#xb5;Ci/gm)12 13. This value was based on the previous radiological risk estimates from the Biological Effects of Ionizing Radiation I report (BEIR I), dose factors from Handbook 69, Maximum Permissible Concentrations of Radionuclides in Air and Water for Occupational Exposure, published by the National Bureau of Standards in 1959 and amended in 1963.
When revised to reflect the current regulations; the 1991 revision of 10 CFR Part 20 (effective January 1994) updated the limits of air concentration for occupational exposures to reflect improvements in the knowledge of biokinetics14. 10 CFR Part 20 was updated to implement Federal Guidance Report No.1115. Federal Guidance Report No. 11, published in September 1988, provides derived guides (i.e., limiting values) of radionuclide intake and air concentration for control of occupational exposure that are consistent with
 
1987 Federal Guidance Document, Radiation Protection Guidance to Federal Agencies for Occupational Exposure. The revised RCS tritium control value is &#xb5;Ci/gm. As the estimated RCS average tritium activity for the realistic model is  m, a value less than the updated Tritium Control Value, no additional action is required (i.e., no modifications to TVA's current boron
-control feed and bleed methodologies
 
(366,000 gallons cycle letdown)). If in the unlikely event the estimated RCS average tritium activity was projected to exceed the recommended RCS tritium Control Value, TVA will take further action to minimize the onsite and offsite radiological impacts of abnormal RCS tritium levels. These actions may include, but not be limited to increased RCS feed and bleed operations, consistent with plant operational requirements, via the Chemical and Volume Control System (CVCS) to liquid effluent pathway Tritiated Water Storage Tank (TWST).
 
Tritium is a radioactive isotope of hydrogen with a half
-life of 12.3 years. Tritium undergoes beta decay, with a maximum energy of 18.6 KeV. The average energy is 5.7 KeV. This low energy limits the maximum range of a tritium beta to about 6 millimeters in air and 0.0042 millimeters in soft tissue. Therefore, the primary radiological significance of exposure to tritium is in the form of internal exposure. Tritium occurs naturally due to cosmic rays interacting with atmospheric gases. In the most important reaction for natural production, a fast neutron interacts with atmospheric nitrogen. Tritium is almost chemically identical to the other hydrogen isotopes and can exist in several chemical forms including:
tritiated water (HTO) tritiated gas (HT) organically bound tritium (OBT)
The most common form of tritium is HTO, where a tritium atom replaces a hydrogen atom in water (H 2O) to form HTO. HTO has the same chemical properties as water and is also odorless and colorless. The majority of tritium in the atmosphere and Commercial Light Water Reactors (CLWR) is in the form of HTO which can be transferred to humans by inhalation, skin absorption (liquid and vapor), or ingestion of drinking water or food. HTO exposure is generally the most important consideration in assessing dose, because HTO quickly reaches equilibrium with water in the body and is distributed uniformly to all soft tissues. International Commission on Radiological Protection (ICRP) (197917) recommended that internalized HTO be assumed to be completely and instantaneously absorbed and distributed uniformly with all body water. As a result, the concentration in sweat, sputum, urine, blood, perspiration, and exhaled water vapor is taken to be the same. HTO is excreted via urine, feces, sweat, and breath.
HT is formed when a tritium atom replaces a hydrogen atom to form a tritium- hydrogen bond. In its elemental form, HT is an invisible, odorless gas chemically identical to hydrogen gas. HT is relatively inert in biological systems and has a very low uptake into body fluids and tissues. The main exposure pathways of HT include inhalation or skin contact with HT
-contaminated surfaces. Releases from tritium processing facilities (such as self
-luminous light manufactures, tritium recovery facilities and nuclear fuel processing facilities) represent the primary source of exposure to HT. HT can be oxidized in the atmosphere to HTO.
Following an intake of tritium (typically in the form of HTO) by plants or animals, a fraction of the tritium can become incorporated into organic molecules such as carbohydrates, fats, or proteins and is termed OBT. Within the body, OBT can become incorporated into various compounds such as amino acids, sugars, and structural materials. OBT can also enter the body directly by ingestion of tritiated food, by inhalation of volatile organic vapors or aerosols.
Tritium is the only radioactive isotope of the element hydrogen.
 
Tritium atoms can replace hydrogen in water molecules to form HTO, in organic molecules to form OBT and in air to form HT. Tritium is one of the lowest energy beta particle emitters. When it is incorporated into the body, more tritium is required than other radioisotopes to cause the same dose.
Tritium occurs both naturally and as a by
-product of the operation of nuclear power and research reactors. It can pose a health risk if it is ingested through drinking water or food, or if it is inhaled or absorbed through the skin in large quantities.
Radiation doses from tritium cannot be measured directly and so are usually estimated by measuring the tritium in bioassay samples (such as urine) or through environmental monitoring (air sampling). Once an estimate of the quantity of tritium in the body is made, the dose can be calculated by using biological models that estimate the concentration of tritium in organs and tissues. For intakes as HTO, the current model assumes instantaneous translocation to blood. It is further assumed that HTO is transferred from the blood, with a biological half
-life of 6 hours and then distributed uniformly throughout the body. The model assumes that 97% of tritium taken in remains as HTO once distributed, while 3% is converted to OBT. In adults, HTO is retained with a biological half
-life of 10 days, and OBT is retained with the biological half
-life of carbon, which is 40 days. The committed effective dose
-per-unit intake (dose coefficient) to adults resulting from the intake of HTO, as recommended by the ICRP (ICRP, 199319; ICRP, 1995a20), is based on Figure 3. This model considers the ICRP's recommendations for radiation weighting factors as well as tissue weighting factors. The committed effective dose
-per-unit intake is the computed effective dose received up to 50 years following a single intake for adults, and up to 70 years for intakes by infants and children. The value for intakes of HTO by adults computed by the ICRP is 1.8 x 10-11 Sv/Bq (0.066 mrem/&#xb5;Ci).
The Federal Guidance Report 1121 value (Technical basis for Appendix B to Part 20
-Annual Limits on Intake (ALIs) and Derived Air Concentrations (DACs) of Radionuclides for Occupational Exposure; Effluent Concentrations; Concentrations for Release to Sewerage22 for adult committed effective dose
-per-unit tritium intake is 1.73 x 10
-11 Sv/Bq (0.064 mrem/&#xb5;Ci). Current NRC Regulations were developed prior to the latest ICRP recommendations and do not account for OBT. Because of the low beta energies, liquid scintillation counting is a convenient, reliable, and practical way of measuring tritium in the liquid phase. The technique consists of dissolving or dispersing the tritiated compound in a liquid scintillation cocktail, and counting the light pulses emitted from the interaction between the tritium betas and the cocktail. The light pulses are counted by a pair of photomultiplier tubes which, when coupled with a discriminator circuit, can effectively distinguish between tritium betas and those from other radioactive sources.
Regarding tritium sources, in a non
-Tritium Production Core (non
-TPC), the production of tritium in the R CS is primarily the result of tritium production/release from:
Fuel Rods (Ternary fission and Integral Fuel Burnable Absorbers (IFBAs)),  Control Rods,  Secondary neutron source rods,  Wet Annular Burnable Absorbers (WABAs),  RCS Deuterium (Heavy Water) activation,  RCS Boron activation, and RCS Lithium activation.
A review of Westinghouse PWR benchmark tritium data23 indicates a nominal production/release tritium value of about 870 Ci/y ear/unit. This nominal value is consistent with the 845 Ci/y ear unit average non
-TPC tritium effluent total observed over the four year period (1997 - 2000) at WBN and Sequoyah (SQN).
Following the review guidance in Chapter 11, "Source Terms," in NUREG-800 Standard Review Plan 24 , TVA uses two source terms for the effluent evaluations:  radwaste system design basis source term and realistic source term. The definition of these two source terms is consistent with the description of the source terms found in Section C.I.11 of Regulatory Guide 1.1206.25 "
 
Gamma ray sources were considered in the plant design, they included fission and corrosion product sources, as well as activation sources such as the nitrogen-16 activity in the primary coolant. The changes in nuclide inventories were addressed in the tritium production NRC SE for WBN Unit 1 License Amendment 4027 , "
 
The August 20, 2001 submittal addressed a TPC with 2,304 TPBARs and is considered bounding for the other than tritium nuclides.
 
Kr 85m 3.95E+07 2.69E+07 Kr 85 9.99E+05 8.81E+05 Kr 87 7.59E+07 5.23E+07 Kr 88 1.08E+08 7.38E+07 Xe 133 2.03E+08 1.88E+08 Xe 135m 5.46E+07 3.59E+07 Xe 135 5.55E+07 4.96E+07 Xe 138 1.79E+08 1.59E+08 I 131 8.80E+07 9.01E+07 I 132 1.34E+08 1.31E+08 I 133 1.97E+08 1.88E+08 I 134 2.31E+08 2.08E+08 I 135 1.79E+08 1.76E+08 Note 1:  WBN 96-Feed Equilibrium Core End
-of-Cycle Operation at 3480 MWt for 510 days.
The cycle quantity of tritium produced and the Radwaste System Design Basis production/release in the RCS (Radwaste System Design Basis activity levels are considered in the process capacity design of plant systems and shielding) for the WBN reactor may be found in Table 11A
-1 of the UFSAR. The annual Radwaste System Design Basis for a non
-TPC is summarized in Table 2.
 
Indirect/reactor component 14,057 1,462 Direct/Soluble 427 427 Total  14,484 1,889 Notes: Power level = 3565 Megawatt (thermal)
Release fraction from fuel = 10% Design, 2% Expected Release fraction from burnable poison rods = 10% Design, 2% expected  Operating time = 495 days RCS Lithium concentration = 2.2 parts per million (ppm)
Initial RCS boron concentration = 1100 ppm.
The annual Radwaste System Design Basis tritium production/release with TPBARs is summarized in Table 3.
Non-TPC Tritium 14,484 1,889 TPBARs ( with  Curies/TPBAR/Year permeation)
Total  Notes: At the end of the operating cycle, the maximum available tritium in a single TPBAR is calculated to be about 11,600 Ci (or 7,733 Ci/year). The average TPBAR will contain about 9,200 Ci (or 6,133 Ci/year) of tritium at the end of the operating cycle.
The NRC's regulatory guidance on WBN's nominal tritium production is found in NUREG-0017 R128. The calculated realistic WBN 1 average annual tritium value from NUREG-0017 R1 is 1,392 Ci. The NRC tritium value with the addition of th e
( TPBARs at Ci/y ear) for a total average annual tritium curies from the TPC was used by TVA to demonstrate continued compliance with the offsite ALARA dose objectives of 10 CFR Part 50 Appendix I.
When reviewing station annual tritium effluents, it is important to recognize that plants such as WBN Unit 1 operate with 18
-month fuel cycles which tend to generate more non
-TPBAR tritium early in the core cycle, owing to higher initial boron concentrations and/or burnable poisons and IFBA rods that are required for reactivity control and more TPBAR-generated tritium later in core life as the tritium inventory within a TPBAR increases from 0 curies at the beginning of the cycle to an average of about curies at the end of cycle. Figure 4 provides estimated Cycle 12 daily tritium RCS production/permeation rates for WBN Unit 1 with 540 M ark 9.2 TPBARs and four Lead Use Assemblies.
The production by the soluble sources (i.e., Boron, and Lithium) decrease as the RCS is diluted to compensate for fuel burn up (i.e., peak RCS boron 1,615 ppm, End of Cycle RCS boron 62.4 ppm). Reactor component tritium production sources consist of fuel rods, control rods, secondary source rods, and WABAs. Reactor component tritium production tends to remain relatively flat (slight increase) for the cycle. The tritium is produced within the components and permeates through the cladding into the RCS. The TPBAR source term is a function of the number of installed TPBARs and may be related to their physical location within the core (neutron flux and temperature). Estimated TPBAR permeation continues to increase throughout the fuel cycle, with a constant power level.
The overall combined tritium producing sources demonstrate increasing daily tritium releases to the RCS. Because of operational constraints and the time required to process RCS discharges for the non
-tritium radioactive components, station tritium effluent releases may occur subsequent to the year of production and tritium release to the RCS. 
 
The typical RCS tritium concentrations pattern for breaker
-to-breaker runs from WBN Unit 1 Cycle 8 are shown below in Figure 5 as an example. WBN Unit 1 non
-tritium production Cycle 3 demonstrated a similar pattern. Cycles with breaker
-to-breaker runs tend to demonstrate the highest peak RCS tritium concentrations.
 
WBN latest complete Tritium Production Cycles 11 and 12 were not breaker
-to-breaker runs. The cycles experienced down powers and shutdowns, which resulted in large dilutions and subsequent RCS tritium reduction. A comparison of the daily RCS tritium activity for Cycles 11 (544 TPBARs) and 12 (544 TPBARs) is shown in Figure 6 and demonstrates the variability introduced and effect of down powers and outages on RCS tritium activity.
 
The TPBARs irradiated at WBN are designed with a stainless steel cladding and an aluminized internal coating. The tritium is produced by neutron irradiation of lithium aluminate pellets contained within the cladding and is gettered (collected and retained) by annular zirconium sleeves (getters) around the pellets. The aluminized coating and stainless steel cladding act as a barrier to tritium release (Figure 7). TPBARs are designed and fabricated to retain as much tritium as possible within the TPBAR.
Because the majority of TPBAR produced tritium is chemically bonded within the TPBAR, only a small percentage of the produced tritium is available in a form that could permeate through the TPBAR cladding. 
 
As with other tritium producing components (fuel rods, control rods, secondary neutron source rods, etc.) some of the free tritium inventory in the TPBARs will permeate the cladding material and be released to the primary coolant. The design goal for this permeation process is to keep the tritium permeation as low as reasonably achievable. TPBAR permeation is nonlinear with respect to the core's effective full power days (Figure 8). A typical TPBAR's tritium inventory begins at zero at the start of the irradiation cycle and ends with about  Ci of tritium at the end of the irradiation cycle. TPBAR tritium permeation increases with the maximum permeation rates towards the end of the cycle. Figures 4 and 8 demonstrate this process by using the Cycle 12 estimated tritium production.
 
When taking measurements of RCS tritium levels, it is not possible to differentiate between tritium from TPBARs and tritium from other core components and RCS sources, therefore the tritium attributed to TPBARs is determined by subtracting the expected tritium value established by measurements taken in cycles without TPBARs from the total tritium estimated in the RCS with TPBARs. The cumulative TPBAR tritium release at any point in the cycle is calculated as the difference of two larger quantities as described below:
 
(1) The total () cumulative tritium to
-date, TTotal, including that which is currently in RCS (daily measurement) plus the sum of the (estimated) tritium removed from the RCS to
-date via letdown to compensate for water/boric acid injections. This total includes the tritium released from the TPBARs plus tritium from non
-TPBAR sources in the RCS.
TTotal (t) = TCurrent RCS Inventory (t) + TRemoved Letdown (t) (2) The cumulative tritium that would have accrued to
-date, in the absence of TPBARs  (Tnon-TPBAR) from sources including production from soluble boron and lithium, and permeation into the RCS from fuel rods, burnable absorber rods, secondary source rods, and control rods, all of which produce tritium in their internal components. Thus, TTPBAR (t) = TTotal (t) - Tnon-TPBAR (t), and  Tnon-TPBAR (t) = TSoluble Boron (t) + TLithium (t) + TFuel Rods (t) + TBurnable Absorbers (t) + TControl Rods (t) + TSecondary Source Rods (t)30 There can be significant uncertainties in both the total () cumulative tritium to
-date and the cumulative tritium generated from non
-TPBAR sources. This results in a significant uncertainty in the amount of tritium attributable to TPBARs. The estimated cumulative tritium permeation per TPBAR for WBN Tritium Production Cycles 6 - 12 with a 90% uncertainty are shown on Table 4.
Cycle 6 483.7 3.5 +/- 1.1 3.3 +/- 1.2 Cycle 7 489.5 3.5 +/- 1.1 3.2 +/- 1.3 Cycle 8 432.1 2.8 +/- 0.8 2.7 +/- 0.9 Cycle 9 516.6 3.8 +/- 0.8 3.4 +/- 0.8 Cycle 10 513.3 4.3 +/- 0.7 4.0 +/- 0.8 Cycle 11 458.7 3.5 +/- 0.5 3.4 +/- 0.5 Cycle 12 501.5 3.6. +/- 0.6 3.2 +/- 0.6  Site-specific data collected during extended non
-TPC operating cycles (WBN Unit 1 Cycle 3 and SQN Unit 1 Cycle 10, breaker
-to-breaker Non
-TPC cycles) have provided useful data to estimate the impact from tritium production on TVA PWR station radiological conditions. The RCS maximum tritium levels noted during the extended operating cycles were  2.5 Ci/gm with a cycle RCS tritium mean of  1.0 Ci/g m. The TVA experienced end of cycle (pre
-flood up) RCS tritium values have typically been in the 0.1 - 0.3 Ci/gm range for both WBN Unit 1 and SQN. The post-flood up tritium values have typically been in the mid-10 2 Ci/gm range. The extended cycle tritium peak RCS tritium values of  2.5 Ci/gm have resulted in containment peak tritium DAC-fractions of <0.15 for both WBN and SQN with a containment average DAC
-fraction of about 0.08. Because of weepage through valve stems and pump shaft seals, some coolant escapes into the containment and the auxiliary buildings. A portion of the RCS leakage flashes to steam/evaporates, thus contributing to the tritiated water vapor source term, and a fraction remains as liquid, becoming part of the liquid source term. The relative amount of leakage entering the gaseous and liquid phases is dependent upon the temperature and pressure at the point where the leakage occurs. 10% due to flashing and Spent Fuel Pool (SFP) evaporative losses is the assumed gaseous effluent fraction for dose impact modeling (NUREG
-0017, Revision 1), whereas WBN Unit 1 effluent history indicates an average of 5.0%. As tritiated water vapor is not removed by filtration or ion exchange it will be released as gaseous effluent to the environment. A breaker
-to-breaker run will potentially produce the maximum RCS tritium concentration, Cycles 11 and 12 with 544 TPBARs were estimated to max just less than 7.0 &#xb5;Ci/gm. With routine boron control  TPBARs at  Ci/TPBAR/y ear the estimated average Design Basis RCS tritium concentration is estimated to be  &#xb5;Ci/gm. With  TPBARs at Ci/TPBAR/y ear the estimated average Realistic Basis RCS tritium concentration is estimated to be  &#xb5;Ci/gm32. There is a strong correlation between the RCS tritium concentration and the containment airborne
 
in containment) and by inference, offsite gaseous tritium exposure (most significant public tritium exposure pathway (Table 5)). It is understood that containment tritium DAC values are a function of the RCS tritium activity, the transfer of tritium from the RCS to the containment atmosphere (leak rate), and the turnover/dilution of the containment atmosphere through periodic and continuous containment venting and purging. The SFP tritium source term is driven by the SFP tritium concentration and pool temperature.
The projected tritium release to the RCS with a TPC containing TPBARs releasing tritium at the design maximum rate (i.e., Table 3) will result in about a factor of fourteen increase over the Non
-TPC tritium production rate, that is, Ratio = (TPC)
Ci/y ear / (Nominal Core) 1,889 Ci/y ear = . It has been calculated that with no modifications to TVA's current boron
-control feed and bleed methodologies (366,000 gallon cycle letdown), the design basis RCS average tritium value will approximate  C i/gm. This mean value would indicate an estimated an average containment tritium DAC-fraction of about. The design basis estimated containment average tritium DAC
-fraction equates to an effective dose rate of about  mrem/h our. As previously discussed, the primary radiological significance of exposure to tritium is in the form of internal exposure and a potential hazard arises when personnel are exposed to open processes that have been wetted with tritiated liquids. Therefore, the design features of the plant that deal with contamination and airborne radioactivity control such as drain and ventilation systems are potentially challenged. TVA has concluded that the estimated annual Total Effective Dose Equivalent (TEDE) values will be affected. TVA, using the site
-specific data collected during recent extended operating cycles, has evaluated the additional deep
-dose equivalent to select station personnel during TPBAR consolidation and the additional committed effective dose equivalent from possible increased tritium airborne activity in containment.
TVA's current estimate of the TPBAR cycle work scope includes pre
-cycle preparation activities, post cycle hardware removal and handling activities, TPBAR consolidation (including equipment setup and disassembly), shipping activities, and the processing, packaging, and shipping of the irradiated components for an estimated cycle total of 1 mrem/TPBAR33. WBN Unit 1 License Amendment 40 estimated the incremental annual station dose (for 2,304 TPBARs) to be 3.2 rem per year.
TVA estimates that when using Radwaste System Design Basis Tritium values for the TPBAR core, this additional TEDE is about  rem/year for TPBAR handling and consolidation activities ( rem per TPC cycle) and 100 tritium DAC
-hour/Ci/gm RCS Tritium (average internal exposure for 1  Ci/gm average RCS tritium cycles) = 100
* 29.8 Ci/gm mean RCS tritium = 2,980 DAC-hour.* 2.5 mrem/DAC
-hour = rem/year for the additional committed effective dose equivalent from possible increased tritium airborne activity in containment. This estimated total additional rem/year is an increase of 23% of the current WBN station average annual dose of 40 rem. WBN's current 3 year collective TEDE per reactor years 2010 - 2012 is 39.998 rem34. WBN is a top quartile Occupation Radiation Exposure performer. An additional annual average  tritium rem would raise the TEDE total to  rem, a value that remains well within the 149 rem assessment35 total. The effect of WBN Unit 1 operation with a T PC containing up to TPBARs (Design Basis) will have a minimal effect on the Radwaste System Design Basis and realistic fission and corrosion product sources and the treatment of these isotopes in liquid and gaseous waste36. The Radwaste System Design Basis tritium sources are estimated to increase the amount of tritium that is discharged annually by a factor of about . The analyzed gaseous releases are based on the design basis tritium source term. For liquid releases, the maximum allowable liquid concentration of tritium was determined.
The gas design release concentrations are below the 10 CFR Part 20 Appendix B Table 2 limits. The Xe-133 is the dominant gaseous isotope released. With the mobile demineralizer system processing the regeneration waste, the liquid design releases are below the 10 CFR Part 20 limits. The design of the gas and liquid radwaste systems meet the requirements of 10 CFR Part 20. The buildup of tritium in plant liquid volumes can create undesirable radiological conditions if the concentration increases to levels on the order of 2 to 4 &#xb5;Ci/gm of water The DOE and NRC concerns for liquid tritium activity in the range of 2 to 4 &#xb5;Ci/gm were restated as a 3.5 &#xb5;Ci/g m Control Value with recommended actions to maintain liquids below the tritium Control Value. These tritium values were based on the pre
-1994 Maximum Permissible Concentration (MPC a) values of 10 CFR Part 20. The 1991 revision of 10 CFR Part 20 (effective January 1994) updated the limits of air concentration for occupational exposures to reflect improvements in the knowledge of biokinetics39. 10 CFR Part 20 was updated to implement Federal Guidance Report No.
1140 , which.was published in September 1988. It provides derived guides (limiting values) of radionuclide intake and air concentration for control of occupational exposure that are consistent with 1987 Federal Guidance Document, Radiation Protection Guidance to Federal Agencies for Occupational Exposure. The derived guides serve as the basis for regulations setting upper bounds on the inhalation and ingestion of, and submersion in, radioactive materials in the workplace. The report also includes tables of exposure
-to-dose conversion factors for general use in assessing average individual committed doses in any population that is adequately characterized by Reference Man.
With respect to HTO (tritium in the form of water vapor) exposure, the concentration in air required to result in an exposure of 2.5 mrem was increased from 5 x 10
-6 Ci/ml to 2 x 10 5 Ci/ml; an increase of a factor of four.
The Westinghouse design documentation41 also predates the updated tritium dose factors. The Westinghouse recommended upper ranges for tritium are based on tritium data that Westinghouse collected in the 1970's from the Millstone, Ginna, and Connecticut Yankee Nuclear Stations and are predicated on the pre
-1994 Maximum Permissible Concentration (MPC a) values of 10 CFR Part 20. Similarly, Regulatory Guide (RG) 8.32 was issued by the NRC in 1988 and as such does not reflect the updated dose factors promulgated in the revision to 10 CFR Part 20 (effective January 1994).
Applying the updated dose factors to the DOE and NRC tritium Control Value yields a revised recommended RCS tritium Control Value of  &#xb5;Ci/g m. The revised concern range is  &#xb5;Ci/g m. The estimated RCS average tritium activity for the realistic model is  Ci/g m, a value less than the updated recommended Tritium Control Value. The estimated RCS average tritium activity for the Radwaste System Design model is  Ci/g m, a value in excess of the recommended Tritium Control Value.
As the estimated RCS average tritium activity for the realistic model is m, a value less than the updated Tritium Control Value, no additional action is required i.e.(no modifications to TVA's current boron
-control feed and bleed methodologies (366,000 gallon cycle letdown)).
If in the unlikely event the estimated RCS average tritium activity was projected to exceed the recommended RCS tritium Control Value, TVA will take further action to minimize the onsite and offsite radiological impacts of abnormal RCS tritium levels.
These actions may include, but not be limited to increased RCS feed and bleed operations, consistent with plant operational requirements, via the CVCS to liquid effluent pathway TWST.
From an in
-plant and public dose ALARA perspective, it is preferable to operate with the mean RCS tritium concentrations below the recommended RCS tritium Control Values.
To continually monitor TPBAR performance, TVA has established performance metrics with two tritium-based action levels. These action levels are cycle specific and are based on the difference between the total calculated tritium released to the RCS (current RCS inventory plus removed via letdown) from all sources minus the estimated tritium released to the RCS from the traditional non-TPBAR sources (boron, lithium, fuel rods, control rods, secondary source rods, WABAs, etc.), that is, the net estimated TPBAR tritium.
Action level 1 is triggered when the net cumulative estimated TPBAR tritium exceeds 1.5 the TPC estimated value. Action level 2 is triggered when the net cumulative estimated TPBAR tritium exceeds triple the TPC estimated value. The Action level 1 value of 1.5 is approximately the 95% confidence level of the total uncertainty in the net estimated TPBAR tritium value. That is, if exceeded there is a 5% probability that the estimated value is consistent with expected TPBAR permeation performance. The TPC estimated valueis at a specific time in the cycle dependent calculated value. The tritium attributed to TPBARs is determined by subtracting the expected tritium value established by measurements taken in cycles without TPBARs from the total tritium measured in the RCS with TPBARs, the estimated value is established prior to each cycle and is based on the number of TPBARs to be irradiated during the cycle and observed previous TPBAR permeation performance. For a specific fuel cycle Effective Full Power Day, the Action Level Trigger follows:
ALTrigger = (Total RCS Inventory - non-TPBAR Sources) / TPC Estimated Value The use of the cycle specific TPC estimated value as the permeation performance metric compensates for RCS water balance (water makeup and letdown) and the cycle's reactor power history. The lower action level requires more frequent tritium system sampling to monitor, verify, track, and trend the tritium levels. In the unlikely event that the higher action level is exceeded, WBN will take further action to minimize the onsite and offsite radiological impacts of abnormal RCS tritium levels. These actions may include, but not be limited to, procedural and administrative measures that will serve to:
ensure that the core is operated consistent with design objectives act as a trigger for increased data monitoring, tracking and trending provide a catalyst to prompt appropriate state, federal, contractual, and regulatory notifications initiate appropriate recovery and restoration actions aid in the development of appropriate actions for minimizing the impact of unexpected tritium production increases on:
worker dose dose to members of the public the potential uncontrolled release of radioactive material low level waste Specific actions and evaluations are contained within WBN Technical Instructions
.The WBN Unit 1 License Amendment 40 RCS tritium fixed action levels of 9 Ci/gm and 15 Ci/gm were based on a cycle inventory of 2,304 TPBARs and breaker
-to-breaker runs. The fixed action levels were insensitive to variations in the number of TPBARs and RCS water balance and without merit (Figure 6). Using the revised realistic TPC source terms for TPBARs, the offsite radiation incremental tritium doses calculated for releases of radionuclides in liquid and gaseous effluents during normal operation are summarized in Table 5. This table also lists WBN's regulatory established radioactive effluent guidelines and the values previously estimated in the WBN Unit 1 License Amendment 40.
TPBARS Updated Tritium Dose
 
Maximally Exposed Individual (mrem)0.55 0.55 5.00 Whole Body Maximally Exposed Individual (mrem) 8.8  (Bone) See Note 1  (Thyroid) 10.6 (Bone)15.00 Organ 50-mile Population Dose (Rem) 7.01 (Bone)
  (Thyroid) 10.7 (Bone)NA Maximally Exposed Individual (mrem) 0.40 0.433.00 Whole Body Maximally Exposed Individual (mrem) 0.55 (Liver)
  (Liver) 0.57 (Liver) 10.00 Organ 50-mile Population Dose (Rem) 3.6 (Thyroid)  (Thyroid) 6.7 (Thyroid)NA Note 1:  With the inclusion of C
-14, as required by Revision 2 of RG 1.21, Bone became the Critical Organ,  Table 5 demonstrates that the calculated WBN station effluent doses are already well below the NRC ALARA guidance levels, so that the small increase in the reactor coolant activity from the tritium and resultant environmental releases would have a negligible effect on the offsite doses, which continue to remain well below the NRC's guidance levels. These values are considered to
 
be non-significant.
For normal TPC operations, the additional solid waste associated with TPCs that TVA will need to handle will be the base plate and thimble plug assemblies that remain after TPBAR consolidation activities. TVA will consolidate and temporarily store these items on
-site. Offsite shipment and ultimate disposal is conducted in accordance with agreements between TVA and DOE. WBN Unit 1 License Amendment 40 estimated activity inventory associated with these additional irradiated components43 (112 base plates and 384 thimble plugs) is 5,921 curies per cycle (180 day post irradiation decay) or an average of 3,527 curies per year when adjusted to reflect measured dose rate44 for Base Plate with 24 Thimble Plugs following 113 day decay adjusted to 180 days (WBN Survey 010201 #2). This represent ed an increase from the current WBN Unit 1 UFSAR estimated non
-TPC value of 1,800 Ci
/year to approximately 5,530 Ci
/year for a TPC. This increased activity is associated with metal activation products. The estimated disposal volume of this additional solid waste is 50 cubic feet per TPC operating cycle or an average of 33.3 cubic feet per year.This additional volume is an insignificant increase in the WBN Unit 1 annual estimated non-TPC solid waste (from the UFSAR), from 32,820 cubic feet per year to 32,853 cubic feet per year for a TPC. For abnormal TPC operation, where increased feed and bleed operation may be used to reduce tritium levels in the RCS, the increased resins that may result from the increased feed and bleed operation will be stored at TVA in suitable containers. Offsite shipment and ultimate disposal will be according to established agreements between TVA and DOE. The amount of increase associated with abnormal TPC operation is estimated to be an additional 600 Ci and an additional 30 cubic feetThis additional volume is an insignificant increase in the WBN annual estimated solid waste (from the UFSAR), from 32,820 cubic feet per year to 32,850 cubic feet per year.WBN Unit 1 License Amendment 40 assessed the environmental impact from the solid radioactive waste associated with the production of 2,304 TPBARs. The WBN revised license amendment establishes as the maximum number of TPBARs per cycle.
Thus, the tritium production solid radioactive waste environmental impact is bounded by the WBN Unit 1 License Amendment 40 impact assessment.
WBN Unit 1 License Amendment 40 assessed the environmental impact from the storage of additional spent fuel associated with the production of 2,304 TPBARs. The number of additional fresh fuel bundles per cycle due to tritium production was set to approximately
: 20. The proposed license amendment establishes  as the maximum number of TPBARs per cycle. This level of TPBAR irradiation will require approximately four additional fresh fuel bundles per cycle.
Thus, the tritium production additional spent fuel generation environmental impact is bounded by the WBN Unit 1 License Amendment 40 impact assessment.
The American Nuclear Society (ANS) classification of nuclear plant conditions divides' plant conditions into four categories according to anticipated frequency of occurrence and potential radiological consequences to the public. The four categories are as follows:
Condition I:
Normal Operation and Operational Transients Condition II:
Faults of Moderate Frequency Condition III:
Infrequent Faults Condition IV:
Limiting Faults The basic principle applied in relating design requirements to each of the conditions is that the most probable occurrences should yield the least radiological risk to the public and those extreme situations having the potential for the greatest risk to the public shall be those least likely to occur.
 
TPBARs were designed to withstand the rigors associated with category I through IV events, therefore, no TPBAR failures are predicted to occur during design
-basis accidents except for a large break loss of cooling accident (LBLOCA) or a fuel handling accident (FHA) involving TPBARs. WBN Unit 1 License Amendment 40 assessed the station accident analyses affected by the production of 2,304 TPBARs. To appropriately account for the radiological consequences of the increased tritium in the TPC, TVA included calculated TEDE45 and Federal Guidance Report Number 1146 dose conversion values for thyroid in the accident analysis. TPBARs are designed to withstand the rigors associated with category I through IV events; therefore, no TPBAR failures are predicted to occur during the design
-basis accidents except for the LBLOCA or the FHA.
To account for the potential available tritium from TPC operation it was assumed that two TPBARs had failed prior to the design
-basis accidents and the tritium was conservatively distributed to the affect components.47  The evaluations considered the postulated release of all the tritium in the two pre
-accident failed TPBARs.
WBNNAL3003 Revision 3, "Reactor Coolant and Secondary Side Activities in Accordance with ANSI/ANS-18.1-1984," served as the basis for the WBN Unit 1 Amendment 40 tritium accident basis activity for the non
-LBLOCA and non
-FHA accident analysis. The assumed RCS tritium m. WBNNAL3003 Revision 5, "Reactor Coolant and Secondary Side Activities in Accordance with ANSI/ANS
-18.1-1984," served as the basis for the updated evaluations of tritium accident basis activity for the non
-LBLOCA and non
-FHA accident dose consequence analyses. The assumed RCS tritium activity at the time of the accidents was m, which is based on 2,500 TPBARs with an assumed permeation of 10 Ci/TPBAR/year and two failed TPBARs. The radiological consequences of the pre
-accident failed TPBAR design
-basis accidents in a TPBAR core remain well within a small fraction of the 10 CFR Part 100 and General Design Criteria (GDC) 19 dose limits as shown in Table 6. WBN Unit 1 License Amendment 40 considered 2,304 TPBARs for the LBLOCA.
The radiological consequences of a LBLOCA with TPBARs are bounded by the WBN Unit 1 License Amendment 40 assessment.
The FHA analysis is unaffected by the authorized number of TPBARs allowed in the reactor core and remain bounding. However, the analysis of record has been revised to be consistent with RG 1.183 (Alternate Source Term - AST). In addition, it was also assumed that instead of 100% of the tritium in the spent fuel pool is released following the FHA through evaporation of the pool. There will not be 100% release of tritium from a TPBAR failure in a FHA because there are no high temperatures involved with the FHA and a large fraction of the spent fuel pool will not evaporate in 8 hours, since the spent fuel pool cooling system maintains the temperature below the boiling point. The radiological consequences of a FHA are well within the 10 CFR 50.67 dose limits.
 
Therefore, all design basis accident doses assuming the failure of TPBARs are within the limits of 10 CFR Part 100 and 10 CFR 50.67 for offsite dose consequences, and the limits of GDC 19 and 10 CFR 50.67 for control room operator dose consequences.
 
with pre-accident iodine spike 9.62 x 10-1 rem (beta) 1.28  rem (TEDE) 2 hour EAB: 2.04 x 10-1 rem (beta) 1.22 rem (TEDE) 30 day LPZ: 6.25 x 10-2 rem (beta) 3.52 x 10-1 rem (TEDE) with accident initiated iodine spike 9.45 x 10-1 rem (beta) 6.50 x 10-1 rem (TEDE) 2 hour EAB: 2.35 x 10-1 rem (beta) 1.08 rem (TEDE) 30 day LPZ: 7.19 x 10-2 rem (beta) 3.14 x 10-1 rem (TEDE) with pre-accident iodine spike 6.37 x 10-2 rem (beta) 4.66 x 10-1 rem (TEDE) 2 hour EAB:
9.28 x 10-3 rem (beta) 1.92 x 10-1 rem (TEDE) 30 day LPZ:
4.35 x 10-3 rem (beta) 8.76 x 10-2 rem (TEDE) with accident initiated iodine spike 9.98 x 10-2 rem (beta) 6.35 x 10-1 rem (TEDE) 2 hour EAB: 2.
55 x 10-2 rem (beta) 3.49 x 10-1 rem (TEDE) 30 day LPZ:
2.98 x 10-2 rem (beta) 4.69 x 10-1 rem (TEDE)
 
1  Watts Bar Nuclear Plant (WBN) - Unit 1 - Revision of Boron Concentration Limits and Reactor Core Limitations for Tritium Production Cores (TPCs) - Technical Specification (TS) Change No. TVA-WBN-TS-00-015, August 20, 2001 (ADAMS Accession No. ML012390106).
2  Safety Evaluation by the Office of Nuclear Reactor Regulation Related to Amendment No. 40 to Facility Operating License No. NPF-90 Tennessee Valley Authority Watts Bar Nuclear Plant Unit 1 Docket No. 50-390 , September 23, 2002 (ADAMS Accession No. ML022540925
). 3  TVA Letter to NRC dated March 22, 2005, "Watts Bar Nuclear Plant (WBN) Unit 1 - Tritium Production Program - Unit 1 Cycle 6 Operating Experience," (ADAMS Accession No. ML050870454
). 4  TVA Letter to NRC dated April 25, 2007, "Watts Bar Nuclear Plant (WBN) Unit 1 - Technical Specification Change 07
-01, Revision of Number of Tritium Producing Burnable Absorber Rods (TPBARs) in the Reactor Core," (ADAMS Accession No. ML071210604
). 5  TVA Letter to NRC dated December 31, 2008, "Watts Bar Nuclear Plant (WBN) Unit 1 - Revised Technical Specifications Change WBN
-TS-08 Revision to the Maximum Number of TPBARs that Can Be Irradiated in the Reactor Core Per Cycle (TAC No. MD9396),"
(ADAMS Accession No. ML090090044). 6  TVA WBN Unit 1 Licensing Basis Post-LOCA subcriticality evaluation establishes a 1,792 TPBAR Core load as the maximum configuration. This evaluation uses a 1,900 TPBAR TPC Source Term to provide an additional margin when evaluating Realistic Effluent Releases and a 2,500 TPBAR TPC Source Term to provide an additional margin when evaluating Design Basis Effluent Releases. 7  This Design basis source term is used to assess station occupational exposure and radwaste system capability. It should not be confused with the UFSAR Chapter 15 Accident Design Basis source term used for offsite dose evaluations.
8  TTP-1-3085, Revision 0 , WBN-1 Cycle 12 TPBAR Tritium Release, Deduced From Analysis o f R CS Data. July 18, 2014. Pacific Northwest National Laboratory, Richland, Washington 9  TVA Letter to NRC dated April 25, 2007, "Watts Bar Nuclear Plant (WBN) Unit 1 - Technical Specification Change 07
-01, Revision of Number of Tritium Producing Burnable Absorber Rods (TPBARs) in the Reactor Core.  (ADAMS Accession No. ML071210604) 10  Watts Bar Nuclear Plant, "Updated Final Safety Analysis Report (UFSAR)
." 11  WBNTSR-100, Revision 12 "Design Releases to Show Compliance with 10CFR20". July 16, 2013 12  NDP-98-181, Revision 1, "Tritium Production Core (TPC)," Unclassified, Non
-proprietary version, dated February 8, 1999, by Westinghouse Electric Company.
13  NUREG-1672, "Safety Evaluation Report Related to the Department of Energy's Topical Report on the Tritium Production Core," U.S. NRC. The Office of Nuclear Reactor Regulation. May 1999 14  10 CFR Part 20 Final Rule 56 FR 23391, May 21, 1991 15  EPA-520/1-86-020, Federal Guidance Report No. 11, "Limiting Values of Radionuclide Intake and Air Concentration and Dose Conversion Factors for Inhalation, Submersion, and Ingestion.
" Washington, D.C. 16  Minister of Public Works and Government Services, Canada 2010. Catalogue number CC172
-58/2010E-PDF ISBN 978-1-100-15583-8. Canadian Nuclear Safety Commission (CNSC) INFO
-0799 17  International Commission on Radiological Protection (ICRP), 1979
-1982. Limits for Intakes of Radionuclides by Workers, ICRP Publication 30, Part 1 (and Supplement), Part 2 (and Supplement), Part 3 (and Supplements A and B), and Index, prepared by Committee 2, adopted by the Commission in July 1978, Annals of the ICRP, Pergamon Press, New York, N.Y 18  ICRP, 1994b. Dose Coefficients for Intakes of Radionuclides    by Workers. Publication 68, 24(4), Oxford, Pergamon Press.
19  ICRP, 1993. Age
-dependent doses to members of the public from intake of radionuclides: Part 2. ICRP Publication 67, Annals of the ICRP, 23(3/4), Oxford, Pergamon Press. 20  ICRP, 1995a. Age
-dependent Doses to Members of the Public from Intakes of Radionuclides: Part 4, Inhalation Dose Coefficients. Publication 71, 25(3
-4) Oxford, Pergamon Press.
21  EPA-520/1-86-020, Federal Guidance Report No. 11 1988  Washington, D.C. 22  10 CFR Part 20 Final Rule 56 FR 23391, May 21, 1991 23  Westinghouse Electric Company, October 2000, Evaluation of Waste Management Issues for Operation with a Tritium Production Core (TPC).
24 NUREG-800, Standard Review Plan for the Review of Safety Analysis Reports for Nuclear Power Plants, LWR Edition, dated June 1987 and latest revision, by U.S. NRC.
25 Regulatory Guide 1.206. U.S. Nuclear Regulatory Commission Office of Nuclear Regulatory Research Division 1, June 2007 26 This Design Basis source term is used to assess station occupational exposure and radwaste system capability. It should not be confused with the UFSAR Chapter 15 Accident Design Basis source term used for offsite dose evaluations.
27 Safety Evaluation by the Office of Nuclear Reactor Regulation Related to Amendment No. 40 to Facility Operating License No. NPF-90 Tennessee Valley Authority Watts Bar Nuclear Plant Unit 1 Docket No. 50-390 , September 23, 2002 (ADAMS Accession No. ML022540925
). 28 NUREG-0017, Revision 1, "Calculation of Releases of Radioactive Materials in Gaseous and Liquid Effluents from Pressurized Water Reactors" 29 TTQP-1-015, Revision 19, "Description of the Tritium
-Producing Burnable Absorber Rod for the Commercial Light Water Reactor. Pacific Northwest National Laboratory, Richland, Washington.
30 TTP-1-3016, Revision 1 , MARK 9.2 (FLG Design) TPBAR Tritium Release, Deduced from Analysis and Qualification of WBN Cycle 9 RCS Data. Pacific Northwest National Laboratory, Richland, Washington.
31 TTP-1-3085, Revision 0, WBN-1 Cycle12 TPBAR Tritium Release, Deduced From Analysis Of RCS Data. Pacific Northwest National Laboratory, Richland, Washington.
32 WBNNAL3003 , Revision 5. Reactor Coolant and Secondary Side Activities in Accordance with ANS1/ANS-18,1-1984 33 Operational experience, cycles 8 - 10, for all related activities (pre
-work, TPBAR Handling fixture setup, Consolidation, fixture storage, production and Post Irradiation Examination shipping, waste hub disposal, cleanup and post-work activities) averaged 0.46 mrem/TPBAR. Rounded upward to 1 mrem/TPBAR to handle contingencies.
34 NUREG-0713, Occupational Radiation Exposure at Commercial Nuclear Power Reactors and Other Facilities, 2012, Vol. 34, U.S. Nuclear Regulatory Commission, April 2014. 35 Watts Bar Nuclear Plant, "Updated Final Safety Analysis Report (UFSAR)
." 36 WBNTSR-100, Revision 12, "Design Releases to Show Compliance with 10CFR20". July 16, 2013 37 NUREG-1672, "Safety Evaluation Report Related to the Department of Energy's Topical Report on the Tritium Production Core," U.S. NRC. The Office of Nuclear Reactor Regulation. May 1999 38 NDP-98-181, Revision 1, "Tritium Production Core (TPC)," Unclassified, Non
-proprietary version, dated February 8, 1999, by Westinghouse Electric Company. 39 10 CFR Part 20 Final Rule 56 FR 23391, May 21, 1991 40  EPA-520/1-86-020, Federal Guidance Report No. 11 Limiting Values of Radionuclide Intake and Air Concentration and Dose Conversion Factors for Inhalation, Submersion, and Ingestion. Washington, D.C.
41 Standard Information Package - SIP Volume 3
-1, "Radiation Analysis Design Manual, Standard Plant - Model 412", Revision 3, November 1978.
42 U.S. Nuclear Regulatory Commission. Regulatory Guide 8.32. Washington, DC. Superseded by NUREG
-1736 . November 2001 43 Pacific Northwest National Laboratory, 1999,  44 BP-263, "" 45 10 CFR Appendix B to Part 20
--Annual Limits on Intake (ALIs) and Derived Air Concentrations (DACs) of Radionuclides for Occupational Exposure; Effluent Concentrations; Concentrations for Release to Sewerage 46 EPA-520/1-86-020, Federal Guidance Report No. 11 Limiting Values of Radionuclide Intake and Air Concentration and Dose Conversion Factors for Inhalation, Submersion, and Ingestion. Washington, D.C.
47 Watts Bar Nuclear Plant (WBN) - Unit 1 - Revision of Boron Concentration Limits and Reactor Core Limitations for Tritium Production Cores (TPCs) - Technical Specification (TS) Change No. TVA-WBN-TS-00-015, August 20, 2001 (ADAMS Accession No. ML012390106).}}

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