ML20126M228

Forwards Partial Response to Generic Ltr 85-02 Re Steam Generator Tube Integrity.Addl Response Will Be Completed by 850901.Program for Steam Generator Tube Integrity & Rupture Mitigation Encl

ML20126M228
Person / Time
Site:	Trojan File:Portland General Electric icon.png
Issue date:	06/14/1985
From:	Withers B PORTLAND GENERAL ELECTRIC CO.
To:	Thompson H Office of Nuclear Reactor Regulation
References
GL-85-02, GL-85-2, TAC-58097, NUDOCS 8506200263
Download: ML20126M228 (9)

Text

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- umans nyt0 w m s vm he-M June 14, 1985 Trojan Nuclear plant Docket 50-344 LLconso NPF-1 Mr. Ilugh L. Thompson, Jr. , Dicoctor Divlslon of LLconsing Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commlssion Washington DC 20555 Dear Mr. Thompson Steam Cenorator Tubo Integrity Generic Lotter 85-02 Generic Lotter 85-02 of AprL1 17, 1985 requested licenseen to provido information which would allow the NRC to assoas the licensee's overall program fot unsuring steam generator tube integrity and for steam generator tubo rupturo mitigation. A description of our overall program as compared to thJ NRC recommended actions is attached. We have not completed our response to Enclosure 2 of the Cenoric Letter. We expect this responso to be complete by September 1, 1985.

Sincoroly, e

Bart D. WLthors Vice president Nuclear Attachment et Mr. Lynn Frank, D1roctor State of Oregon Department of Energy Mr. S. J. Green EPR1 l

0506200263 030614 PDR ADOCK OD000344 P PDR b -

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Trojan Nuclear Plant Mr. H. L. Thompson Docket 50-344 June 14, 1985 License NPF-1 Attachment 1 Page 1 of 7 STEAM CRNERATOR TUBE INTEGRITY PROGRAM

1. Prevention and Detection of Loose Parts,

s. Inspections.

WRC Recommendation Visual inspections should be performed on the steam generator secondary side in the vicinity of the tubo sheet, both along the entire periphery of the tube bundle and along the tubo lane, for purposes of identifying loose parts or foreign objects on the tube sheet, and external damage to peripheral tubes just above the tube sheet. An appropriate optical device should be used (eg, minL TV camera, fiber optics). Loose parts or foreign objects which are found should be removed from the steam genera-tors. Tubes observed to have visual damage should be eddy current inspected and plugged if found to be defective.

These visual inspections should be performed (1) For all steam generators at each plant at the next planned outage for eddy current testing, (2) After any secondary side modifications, or repales to steam generatoe internals, and  !

(3) When eddy current indications are found in the free-span portion of peripheral tubes, unless it has been established that the indleation did not result from damage by a loose part or foreign object.

For PWM OL applicants, such inspections should be part of the preservice inspection.

For steam generator models whero certain segments of the peripheral region can be shown not to be accessible to an appropriate optical devico, licenseos and applicants should implement alternative actions to address these inaccessible areas, as appropriato.

Licenseco should take appropriate precautions to minimiro the potential for corrosion while the tubo bundio is exposed to air.

The presence of chemical species, such as sulfur may aggravato this potentlat, and may make exposure to the atmosphoro inadvisable until appropriato remedla1 measures are takon.

Trojan Nuclear Plant Mr. H. L. Thompson Docket 50-344 June 14, 1985 License NPF-1 Attachment 1 Page 2 of 7 FCE Response PCE has procedures in place which require visual inspections on the steam generator secondary side any timo that the secondary side is opened for maintenance or any time foreign objects are suspected. These inspections are conducted with appropriate optical devices and include both the entire periphery of the tube bundle and along the tube lano. If the results of the visual inspections are determined to be unsatisfactory, either becauso looso parts or degraded tubes are found, then the appropriato supervisors are notLfied and th(y determlno the corrective action.

Str.co 1983, peripheral inspections using a boroscope have boon performed on the steam generators following opening. Loooo parts were found and renoved from the "A" steam generator in 1984. The inspection program has boon upgraded in 1985 due to the acquisi-tion of a new video boroscope. Video tapes of the steam genera-tor inspections are now made in lieu of 35 mm photographs. Video cassetto tapes will provido a historical reference for futuro uso.

b. Quality Assuranco.

NRC Recommendation Quality assurance / quality control procedures for steam generators should be reviewed and revised as neconsary to ensure that an entfective system exists to preclude introduction of foreign objects into olther the primary or secondary sido of the steam generator whenover it is open (eg, for maintenanco, sludge lancing, repairs, inspection, operations, modifications). As a minimum, such procedures should include (1) Detalled accountability proceduros for all tools and equip-ment used during an operation, (2) Appropriato controls on foreign objects such as oyeglasses and film badges.

(3) Cleanlinoss requiroments, and (4) Accountability proceduros for components and parts removed from the internals of major components (eg, reassembly of cut and romoved compononto).

Trojan Nuclear Plant Mr. H. L. Thompson Docket 50-344 June 14, 1985 License NPF-1 Attachment 1 Page 3 of 7 FGE Response PGE's procedures require that material control be established at all times whon a manway to the primary or secondary side of the steam generator is open with the exception that it is not required for the primary side if nozzle covers or dams are installed. The material control requirements include detailed accountability for all material entering and leaving the steam generators. All personnel entering a steam generator are required to appropriately secure personal items, such as eyeglasses and anti-contamination clothing. PGg's procedures also contain specific cleanliness requirements for the steam l generators.

2. Inservice Inspection Program,

a. Full-Length Tube Inspections.

NRC Recommandation The Standard Technical SpecLfications (STS) and Regulatory Culde 1.83 Part C.2.f. currently define a U-tube inspection as meaning an inspection of the steam generator tube from the point of entry on the hot-leg side completely around the U-bend to the top support of the cold-les side. The staff recommends that tube inspections should include an inspection of the entire length of the tube (tube end to tube end), including the hot-les side.

U-bend, and cold-leg side.

This recommended action does not mean that the hot-leg inspection sample and the cold-leg inspection sample should necessarily involve the same tubes. That is, it does not preclude making separate entries from the hot- and cold-les sides and selecting different tubes on the hot- and cold-les sides to meet the minimum sampling regulrements for inspection.

Consistent with the current STS requirement, supplemental sample inspections (after the initial 3-percent sample) under this staff recommended action may be limited to a partlal length inspection provided the inspection includes those portions of the tube lengths where degradation was found during initir' sampilng.

PGE Response It to currently PCE's practice to inspect both the cold- and hot-leg sLdes of the steam generator tubes, including the U-bend portion.

Trojan Nuclear Plant Mr. H. L. Thompson Docket 50-344 June 14, 1985 License NPF-1 Attachment 1 Page 4 of 7

b. Inspection Interval.

NRC Recommendation The maximum allowable time between eddy current inspections of an individual steam generator should be limited in a manner con-sistent with Section 4.4.5.3 of the STS, and in addition, should not extend beyond 72 months.

PGs Response PGs's current practice is to perform eddy current inspections within the 72-month recommended limit. As evidence of this, the following list indicates the steam generator eddy current inspec-tions performed each year since Trojan received its operating license (1975). In only one case, for the "C" steam generator, was the 72-month limit exceeded.

1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 S/G A X X X S/G B X X X S/G C X X X S/G D X X

3. a. Secondary Water Chemistry Program.

NRC Recommendation Licensees and applicants should have a secondary water chemistry program (SWCP) to minimize steam generator tube degradation.

The specific plant program should incorporate the secondary water chemistry guidelines in SGoc Special Report EPRI-NP-2704, "PWR Secondary Water Chemistry Guidelines", October 1982, and should address measures taken to minimize steam generator corrosion, including materials selection, chemistry limits, and control methods. In addition, the specific plant procedures should include progressively more stringent corrective actions for out-of-specification water chemistry conditions. These correc-tive actions should include power reductions and shutdowns, as appropriate, when excessively corrosive conditions exist.

Specific functional individuals should be identified as having the responsibility / authority to interpret plant water chemistry information and initiate appropriate plant actions to adjust chemistry, as necessary.

Trojan Nuclear Plant Mr. H. L. Thompson Docket 50-344 June 14, 1985 i License NPF-1 Attachment 1 Page 5 of 7  !

The referenced SGOG guidelines above were prepared by the Steam i

! Generators Owners Group Water Chemistry Guidelines Consmittee and j represent a consensus opinion of a significant portion of the ,

, industry for state-of-the-art secondary water chemistry control. ,

j pG messonse i Trojan Technical Specification 6.8.4.c requires that a secondary

. water chemistry program be in place. Trojan's secondary water

) chemistry program incorporates the operating guidelines in the ,

i SGOG Special Report, EPkI-NP-2704, "PWR Secondary Water Chemistry  !

Guidelines", October 1982. Thlw program includes chemistry [

limits, control methods, measures to minimize corrosion, and ,

progressively more stringent corrective actions for out-of- l specification water chemistry conditions. The corrective actions ,

include power reductions when excessively corrosive conditions '

exist. The Plant Chemistry Supervisor is identified as having the responsibility and authority for the secondary water  ;

chemistry program.

Trojan has continued to follow the SGOG guidelines, but even more so has strived to keep steam generator water chemistry at the -!

best chemistry possible. One exception to the operating I guidelines has been taken and that is for the dissolved oxygen action level. Trojan does not decrease power to 30 percent if dissolved oxygen exceeds 10 ppb for 7 days since power reductions significantly change the oxygen ingress and, therefore, do not l allow for identification of leakage in the condenser. Trojan does have an aggressive program for oxygen detection and is fully connaitted to keeping oxygen within the guidelines of 10 ppb.

b. Condenser Inservice Inspection Program, pac Reconumendation Licensees should implement a condenser inservice inspection program. The program should be defined in plant-specific safety-related procedures and include:

(1) Procedures to implement a condenser inservice inspection program that will be initiated if condenser leakage is at such a magnitude that a power reduction corrective action is required more than once per 3-month periodt (2) Identification and location of leakage sources, either water or airs (3) Methods of repair of leakage;

• Trojan Nuclear Plant Mr. H. L. Thompson Docket 50-344 June 14, 1985 License BPF-1 Attachment 1 Page 6 of 7 (4) Nothodology for determining the cause(s) of leakage; and (5) A preventive maintenance program.

PGs Response Trojan has a program for the inspection of the condenser for both air and water in-leakage. The program is not currently defined in specific plant safety-related procedures, however. Trojan uses helium leak detection methods to detect air in-leakage.

Every effort is made to repair leakage rapidly. The helium leak detection methods have also been used in the circulating water boxes to detect water leakage into the condenser. Additionally, visual inspections of the secondary side of the condenser are performed following the breaking of vacuum with full circulating we'er pressure in order to detect any small tube leaks or tube-to-tube sheet leaks that may be present but are not large enough to affect steam generator chemistry. This program has been very effective in identifying extremely low-level leaks before they become a problem to the overall chemistry program.

Eddy current testing (BCT) has been performed as needed, however, no MCT progene is presently planned since nylon inserts have been installed in the condenser tubes because of roll transition cracking. Retubing of the condensers is currently under consideration.

4. primary to Secondary Leakage Limit.

NRC Recommendetton All PWRs that have Technical Specification limits for primary-to-secondary loakage rates which are less restrictive than the Standard Technical Specifications (STS) limits should implement the STS limits.

PGE Response Trojan Technical Specifications are consistent with the STS.

5. Coolant Iodine Activity Limit.

MR9 Roccamendation PWRs that have Technical Specification limits and surveillance for coolant lodine activity that are less restrictive than the STS should implement the STS limits. Those plants identified above that also j have low-head high-pressure safety injection pumps should either:

1. Implement iodine limits which are 20 percent of the STS values, or l

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i Trojan Nuclear Plant Mr. H. L. Thompson  !

Docket 50-344 June 14, 1985 License NPF-1 Attachment 1  !

Page 7 of 7  !

l 2. Implement reactor coolant pump trip criteria which will ensure that if offsite power is retained, no loss of forced reactor (

coolant system flow will occur for steam generator tube rupture I events up to and including the design basis double-ended break of a single steam generator tube, and implement iodine limits consistent with the STS.

PGE Response l

Trojan's Technical Specifications are consistent with the STS.

6. Safety Injection Signal Roset.

PRC Recommendation 1

l The control logic associated with the safety injection pump suction i flow path should be reviewed and modified, as necessary, by licensees to minimize'the loss of safety function associated with safety injec- I tion reset daring an SCTR event. Automatic switchover of safety  !

injection pump suction from the boric acid storage tanks (BAST) to j -

the refueling water storage tanks should be evaluated with respect to whether the switchover should be made on the basis of low BAST level alone without onsideration of the condition of the SI signal.  ;

) ECE Response This issue is not applicable to Trojan.

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O Trojan Nuclear plant Mr. H. L. Thompson Docket 50-344 June 14, 1985 i License NPF-1 Attachment 2 '

REQUEST FOR 1NFORMATION CONCERNING CATEGORY _C-2 -

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NRC Request The one.losed draft NUREG-0844, Section 2.2.1.2 describes cortain limita-tions which the staff belloves tu be inherent in the present Technical Specification steam generator ISI requirements pertalning to Category C-2 inspection results. Licensees and applicants are requested to provide a description of their current policy and actions relative to this issue '

and any recommendations they have concerning how existing Technlent  ;

l Specification steam generator ISI requirements pertaining to Category C-2 '

inspection results could be improved to better ensure that adequato inspections will be performed. This description should include a I

response to the following questions:

1. What factors do, or would, the licensee or applicant consider in

determining (a) whether additional tubes should be inspected beyond l what is requLred by the Technical Specifications (b) whether all steam generators should be included in the inspection program, and

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(e) when the steam generator should be reinspected?

2. To what extent do these factors include consideratlon of the degrada-tion mechanism Ltself and its potentist for causing a tube to be vulnerable to rupture during severo transients or postulated acci- i dents before rupture or leako6e of the tube occurs during normal I operation? ,

EEX_E*fR2nRR -

p0K is still in the process of completing our response to this concern.  !

It is expected that our responso will be completed by coptember 1,1985.

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