ML17256A476

Forwards Response to NRC Re value-impact Analysis of Recommendations Concerning Steam Generator Tube Degradations & Rupture Events Per Generic Ltr 82-32

ML17256A476
Person / Time
Site:	Ginna
Issue date:	01/24/1983
From:	Maier J ROCHESTER GAS & ELECTRIC CORP.
To:	Crutchfield D Office of Nuclear Reactor Regulation
References
GL-82-32, NUDOCS 8301310345
Download: ML17256A476 (14)

Text

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ACCESSION NBR ~ 8301310345 DOC ~ DATE: 83/01/24 NOTARIZED'O DOCKET FACIL:50 244 Robert Emmet Ginna Nuclear Planti Unit li Rochester G

05000204 AUTH BYNAME AUTHOR AFFILIATION MAIERtJ,E ~

Rochester Gas 8 Electric Corp'EC IP ~ NAME RECIPIENT AFFILIATION CRUTCHF IELD e D Q Operating Reactors Branch 5

SUBJECT:

Forwards response to NRC 821209 ltr re value impact analysis of recommendations concerning steam generator tube degradations 5 rupture events per Generic ltr 82~32 ~

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I ROCHESTER GAS AND ELECTRIC, CORPORATION,89 EAST AVENUE, ROCHESTER, N.Y. 14649 WA1E JOHN 6, MAILER Vice Preektent T E i. E P H0 ME AREA CODE Tie 546.2700 January 24, 1983 Director of Nuclear Reactor Regulation Attention:

Mr. Dennis M. Crutchfield, Chief Operating Reactors Branch No.

5 U.S. Nuclear Regulatory Commission Washington, D.C.

20555

Subject:

Potential Steam Generator Related Generic Requirements (Generic Letter No. 82-32)

R. E. Ginna Nuclear Power Plant Docket No. 50-244

Dear Mr. Crutchfield:

By letter dated December 9,

1982, Mr. Darrell Eisenhut re-quested comments, within 30 days of the date of his letter, on the report "Value-Impact Analysis of Recommendations Concerning Steam Generator Tube Degradations and Rupture Events".

The attachment to this letter provides our comments.

Due to the limited time available following receipt of the letter, we informed your Staff that additional time would be required to prepare our response.

Very truly yours, Q~ ill(~~

John E. Maier Sspi3ip~4 pgppp244

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Attachment p

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'h'e Ginna t'ube.rupture 'oc'curred o.January 25',

1982, not.on. January 15," 1982.

Detailed computer analyses by three independent organizations, RGSE, Westinghouse, and INPO, confirm that the maximum leak rate in the Ginna steam generator tube rupture was approximately 600 to 630 gpm.

Thus, this value should be used in lieu of the rough hand calculated value derived by the NRC Staff.

p III.2-2 p III.2-2 Same comment as above.

It is incorrectly stated that 0.3 gpm primary to secondary leakage is the Technical Specification limit which requires plant shutdown.

Not all plants have this limit, it may be higher or lower.

p III.2-4 See the comment above on Technical Specification limits requiring shutdown.

p III.2-11 It should be noted that sleeving of steam generator

tubes, a repair option now available instead of plugging, will extend plant life, assuming that defects are located in the immediate vicinity of the tube sheets.

p III.2-13 It is likely that peripheral tube plugging at Ginna was due, at least in part, to the presence of loose parts.

p III.4-3 It has been our experience that the exposure rate is higher in the hot leg (measurement point 20) than in the cold leg (point 21), typically by a factor of 1.5.

p IV.1-1 It should be clarified that inspections of the "entire periphery" of the steam generator are restricted to the vicinity of the tube sheet.

p IV.1-1 The last sentence of action 1 indicates that inspections are required at each eddy current inspection.

This is contrary to the remainder of that paragraph.

In fact, a one time inspection should be performed to serve as a baseline.

Sub-sequent inspections would be required, as stated in the paragraph, after any secondary side modifications or repairs to steam generator internals or after flaw indications were found in the free span portion of peripheral tubes unless otherwise justified not to be due to loose parts.

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We agree with the conclusions shown that a

LPMS is not necessary.

We also note that there is a lack of sufficient experience at this time in use of LMPS for secondary side monitoring to make it a system which can be used by plant personnel without heavy reliance for highly qualified interpreters of the data.

Thus, it is not now possible to adequately discriminate between true foreign object impacts and other signals on a routine basis.

It should be noted that detailed QA procedures were applied during Ginna steam generator modifications.

Additional procedures might have, but not necessarily would have, precluded foreign objects being intro-duced into the steam generators.

The occupational exposure associated with repairs following steam generator tube ruptures is highly dependent on the mechanism.

Thus, use of the Ginna 350 man-rem may not be justified.

Additional data

.could be obtained from other units whic'h, have experienced tube ruptures.'he estimate that 10% of all tube ruptures will result in steam generator replacement seems quite high given the experience to date.

The cost for a mini-TV camera system which is quoted is not consistent with the Ginna experience.

The Ginna cost to develop a TV camera

system, including development of a transport system to move the camera within the steam generator was approximately

$ 75,000.

The cost impact of adopting the NRC proposed requirements has been understated.

First, steam generator inspection is,,quite often, a critical path activity.

Thus 3 additional days of testing would directly lead to 3 additional days of plant shutdown.

This cost should, therefore, be included.

Second, not all tubes can be inspected without additional steam generator entries.

Additional fixture locations or hand probing of some tubes will be required.

(For example, additional radiation exposure will be incurred in inspecting tubes which are used to support the eddy current fixture.)

Therefore, there is additional occupational radiation exposure associated with this recommendation.

Third, the cost for the plant specific analysis is understated.

Without commenting on the number of man-months estimated, current cost per man-hour appears to be greatly understated by at least 50%

based on our recent experience with similar analysis.

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Thus, even assuming the 9 man-months are correct, a

more realistic cost would be nearly

$ 200,000.

When making these adjustments to the cost-impact, it is likely that this requirement will not be cost beneficial.

If the requirement is adopted, we agree that a

utility should be able to define subsets of tubes for the supplementing inspections.

We agree that to require full steam generator inspection or shutdown due to any leak should not be

required, but rather only on leakage greater than the Technical Specification limit.

An alternative to use of a wear standard could be removal of all foreign objects.

Without foreign objects,'t is unlikely that the,very long wear signals could be generated,

thus, use of a wear standard would not be necessary.

As another alternative, use of the wear standard could be tied to detection of an axial indication with the absolute technique.

The requirement has been improperly stated.

It was our understanding that a secondary water chemistry program would only be required if steam generator tube plugging was required by a chemistry-related phenomenon.

As indicated by a letter to the NRC from the Steam Generator Owners Group (SGOG), the secondary water chemistry guidelines do not represent an industry consensus.

First, not all the industry is represented by SGOG.

Second, not all members of the SGOG agreed with all portions of the Guidelines.

We note that use of a sentinel plug can result in primary to secondary

leakage, increased secondary side activity, reduced ability to detect leakage in in-service tubes during plant operation, increased

releases, and increased occupational exposure.

The assumption that the STS values have been used in accident analyses for all plants is incorrect.

Either higher or lower values may have been used in analyses.

Thus, it would be reasonable to require that the leakage requirement be consistent with analysis,, but not that STS be used if higher limits can be justified.

The text implies that there are separate dose criteria for a tube rupture from releases due to primary to secondary leakage before the incident and

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due to primary to secondary leakage through the ruptured tube.

This is not true.

Thus reference to tube ruptures should be deleted on p IV.8-1, 2, and 4 ~

The cost to implement STS is not negligible if the plant is reguired to shut down and replace leaking fue3, in a situation where its accident analysis can justify high limits and, therefore, continued operation.

The discussion of the basis for the 0.2 uCi/gm limit for low-head plants is largely incorrect.

Reactor coolant pump trip is required for certain classes of small break LOCAs but not for tube ruptures.

RCP operation is acceptable for steam generator tube ruptures.

NRC analyses of the Ginna incident was extremely conservative and assumed that all iodine was released to the environment, with no credit for water remaining within the plant.

Analysis submitted by RGSE by letter dated November 22, 1982 demon-strates that the STS values for iodine are acceptable for under a design basis incident with 30 minute and 60 minute operator action times and under the actual Ginna thermal hydraulic transient.

Thus, there is no need for a special limit on low-head HPSI plants.

The fact that low-head HPSI plants are currently operating below the special limits suggested is not a

basis for believing that this situation will hold true in the'uture'.

Thus, a study of fuel per-formance experience and likelihood of leaking fuel causing unscheduled outages and fuel replacement should be performed.

J As discussed

above, STS limits are acceptable for low-head HPSI plants.

As discussed above, higher, less restrictive limits may be justified in existing or new analyses and cannot be precluded based on 10 CFR 100.

The discussion in Section 10.1.2 implies, that without difficulties in PORV operation, upper head voiding will not occur.

This is incorrect.

If the reactor coolant pumps are tripped, the upper head void will occur.

It should be noted that alternative RCP trip criteria have been developed for Ginna which will permit RCP operation up to and including design basis tube ruptures.

If this is the case for all

plants, then the need for such a study largely disappears.

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The cost of performing studies is identified as being highly variable.

This may be due to lack of specificity in requirements as much as differing plant conditions.

A preferred approach would be for the NRC Staff to provide comments on the Owners Group Emergency Guidelines.

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