ML20132G427
| ML20132G427 | |
| Person / Time | |
|---|---|
| Site: | Waterford  |
| Issue date: | 06/18/1985 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML19283F593 | List: |
| References | |
| NUDOCS 8508050026 | |
| Download: ML20132G427 (3) | |
Text
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 1 TO FACILITY OPERATING LICENSE NO. NPF-38 LOUISIANA POWER AND LIGHT COMPANY WATERFORD DOCKET NO. 50-382 Introduction By letter dated May 14, 1985, Louisiana Power and Light Company (licensee),
requested an emergency change to the Technical Specifications (Appendix A to l
Facility Operating License NPF-38) for the Waterford Steam Electric Station, l
Unit 3.
The proposed change would revise Technical Specification 3/4.3.3.10 and 4.11.1.1.1 to provide sampling and automatic termination of steam generator blowdown through the Circulating Water System and to require continuous sampling for steam generator blowdown to the Waterford 3 waste pond.
Discussion Waterford 3 reached the 80% power test plateau on May 7,1985. The plant is currently experiencing difficulties in maintaining secondary chemistry within specifications. The prime contributors appear to be a steam generator
" hideout" condition, residual contaminants from construction, and air in-leakage. The in-leakage is aggravated by extended low power operation during which the moisture separators / reheaters operate under a partial vacuum.
In addition, operational difficulties involving flushing during regeneration of the full flow condensate demineralizer beds resulted in high concentration of cations and anions in the secondary system and the possible occurrence of organics due to introduction of resin beads into the system.
LP&L also stated that they had experienced some circulating water leakage to the condenser but that this condition has largely been corrected. As a by-product of steam production, contaminants concentrate in the steam generator and represent a potential contributor to steam generator corrosion. Blowing down the steam generators is necessary to remove these contaminants and enhances steam generator tube integrity.
Currently three flow paths exist for steam generator blowdown.
(1) Blowdown can be directed to the radioactive waste management system. This pathway is used primarily when radioactive contaminants are present and is not an optimum p(ath for disposing of normal, routine operation steam generator blowdown.2) Steam returned through the condensate /feedwater system. This path affords some cleanup via the condensate polishers, but at Waterford 3 this system is some-what limited and its use to cleanup steam generator blowdown leads to rapid Cp.wSO50026 850618 DR ADOCK 05000382 PDR
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exhaustion of the demineralizer filter packages.
(3) Finally, steam generator blowdown can be discharged to the Waterford 3 waste pond, however, this flow path is not currently in use because it does not contain appropriate monitors of the liquid effluent release pathway to the environment.
Because a large volume change is necessary to bring the feedwater into specifi-cation in order to circumvent the limitations in the condensate polishino system and avoid the rapid exhaustion of blowdown demineralizers, LP&L finds it necessary to have the ability to feed and bleed the secondary system. To provide this ability, LP&L intends to make modifications to the steam generator blowdown system. One change would provide a pathway from the steam generator blowdown line upstream of the blowdown demineralizers, to the circulating water i
system (CWS) discharge from the blowdown heat exchangers. This modification would utilize the existing monitor on the CWS line to provide an automatic shutoff of blowdown upon receipt of a high radiation signal and would add a continuous sampler in the steam generator blowdown effluent line.
LP&L is proceeding with this modification and estimates that it will take approximately one month to complete and will require approval from the Environmental Pro-tection Agency in the form of a change to the NPDES permit for Waterford 3.
i This modification requires a change to the Technical Specifications in that Tables 3.3-12 and 4.3-8 will reflect a change in the status of the existing CWS radiation monitor from an alarming function to an alarming and termination
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function for the new steam generator blowdown discharge line to the CWS. A continuous sampler will be added to both tables and will be used whenever the CWS pathway for steam generator blowdown is in use. Table 4.11-1 will be modified to require use of the continuous sampler for blowdown to the CWS.
In the interim, until modifications for the blowdown dischare to the CWS are complete and LP&L has received EPA approval, Waterford 3 will use an existino flow path to direct blowdown to the Waterford 3 waste pond. This discharge will be used with the following administrative limitations:
The pathway will not be used when there is detectable radioactivity in the steam generators.
The pathway will only be used when necessary to control secondary 1
chemistry within specifications when the circulating water discharge pathway is not available.
Grab samples of the blowdown will be taken prior to release and at least every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> during blowdown.
The pathway to the waste pond will be manually isolated upon discovery of detectable activity in the pathway to the pond.
i LP&L desires to have this flow path available after the modifications are com-i plete for discharge to the CWS to give them greater operational flexibility in i
the event that NPDES limits on pH or suspended solids, etc., do not permit dis-charge to the CWS but will not normally routinely use this flow path. The Technical Specification Table 4.11-1 will be changed to require that discharges of blowdown to the waste pond be sampled continuously. A notation (note,1) will be included to clarify when sampling and analysis is required as well as to define the conditions under which blowdown may be discharged to the waste pond. An j
additional notation (note k) will, after six months tenninate authorization 4
to use this discharge line without automatic isolation by in line radiation monitors unless modifications to the CWS have been completed and are operable.
Evaluation l
This proposed change falls into the category of an emergency change since i
absent the change, Waterford 3 would be required to shut down to maintain secondary chemistry within specifications. Additionally, it is desirable to maintain secondary chemistry as clean as possible and if contaminants are concentrating in the steam generators, to remove those contaminants as quickly as possible to protect steam generator integrity by limiting corrosion.
LP&L detemined the need for discharge pathways to the circulating water system and the waste pond to maintain acceptable secondary chemistry on April 30, 1985.
Efforts to that point had been ineffective in maintaining secondary chemistry within the requirements of the Secondary Water Chemistry program established in accordance with Section 6.8.4(c) of the technical specifications without changes to the existing facility. The staff recognizes that the prime contributors to secondary chemistry difficulties were residual contaminants from construction, steam generator hideout, air inleakage aggravated by extended low power operation during power ascension testing and system operational difficulties which reasonably could not have been avoided.
On May 1, 1985, the licensee notified the NRC staff and requested a meeting to discuss plant modifications, supporting analyses and related technical specification changes; this meeting was subsequently held on May 9, 1985 in Bethesda, Maryland. The staff considers that the licensee acted in a q
timely manner upon identification that secondary chemistry could not be effectively controlled with the existing plant design.
LP&L has evaluated the off-site dose consequence of this change coincident with the most limiting accident. The most limiting accident from the point of view of off-site dose consequence is the steam generator tube rupture (SGTR) event analyzed in Chapter 15 of the FSAR.
In that event, the off-site dose due to the release of steam from the secondary side safety valves is a factor of 100 under the 10 CFR 100 dose limitation requirements. The effects on the total off-site dose calculated for this event due to super-imposing either a concurrent discharge to the Circulating Water System (CWS) or the Waterford 3 waste pond are minimal.
For the CWS and waste pond pathways, the most adverse consequences are to the thyroid dose attributable to inhalation.
For both pathways the thyroid dose is a small fraction of (one to two orders of magnitude less than) the steam release dose. The additional dose due to the CWS or waste pond pathway thus provides negligible impact on the SGTR event when compared with 10 CFR 100 requirements. As a result, operation of the facility in accordance with the proposed Technical Specification l
changes will not involve a significant increase in the consequences of any accident previously evaluated. The Technical Specification changes are being proposed to provide further means to maintain secondary water chemistry within i
approved specifications. One purpose for maintaining limits on secondary water chemistry is to preserve to the extent possible the integrity of the steam generator tubes. Therefore, the proposed Technical Specification changes will not involve a significant increase in the probability of any accident previously evaluated; rather the proposed changes will assist in maintaining the already low probability of a SGTR event.
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