ML17244A431

Responds to 790103 Request for Review of Steps Following Reactor Shutdown During Postulated Fuel Handling Accident Inside Containment Bldg.More than 100-h Must Elapse After Shutdown Before Fuel Is Handled

ML17244A431
Person / Time
Site:	Ginna
Issue date:	03/27/1979
From:	White L ROCHESTER GAS & ELECTRIC CORP.
To:	Ziemann D Office of Nuclear Reactor Regulation
References
TASK-15-20, TASK-RR NUDOCS 7904050228
Download: ML17244A431 (9)

Text

RF LATORY INFORMATION DISTRI lON SYSTEM (RIDS)

AGGRESSION NBR $ 7904050228 DOC ~ DATE'9/03/27 NOTARIZED!

NO FACIL:50 244 ROBERT EMMET GINNA NUCLEAR PLANTE UNIT ig ROCHESTER G

AUTH'AME AUTHOR AFF ILIATION WHITE E L ~ D ~

ROCHESTER GAS 5 ELECTRIC CORP'EC IP ~ NAME RECIPIENT AFFILIATION ZIEMANNr0 ~ L>>

OPERATING REACTORS BRANCH 2 DOCKET5000244 SUBJECTS RESPONDS TO 790103 REQUEST FOR REVIEW OF1 STEPS INVOLVED AFTER REACTOR SHUTDOWN DURING 'POSTULATED FUEL HANDLING

'ACCIDENT INSIDE CONTAINMENT BLDG ~ CONCLUDES MORE THAN 100 HOURS'UST ELAPSE AFTER SHUTDOWN BEFORE FUEL IS HANDLED'ISTRIBUTION CODE:

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March 27, 1979 Director of Nuclear Reactor Regulation Attention:

Mr. Dennis L. Ziemann, Chief Operating Reactors Branch No.

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

20555

Subject:

Fuel Handling Accident Inside Containment R.E. Ginna Nuclear Power Plant Docket No. 50-244

Dear Mr. Ziemann:

In our letter of March 18, 1977 we provided a detailed evaluation of the potential consequences of a postulated fuel handling accident inside containment.

The analysis showed that the consequences were well within the limits established by 10 CFR Part 100.

In the analysis, we assumed that the fuel handling accident would not occur until at least 100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br /> after shutdown.

Your letter of January 3,

1979 asked that we provide justification that fuel would not be removed from the reactor vessel within 100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br /> after a shutdown or propose a Technical Specification providing such a restriction.

We have performed a

review of the steps which must be accomplished between shutdown of the reactor and fuel handling at Ginna and have found that more than 100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br /> of activities are required before fuel can be handled.

Therefore, no Technical Specification change is required.

A chart. displaying the sequencing and timing for each of the steps required between shutdown and refueling is attached.

The following is a description of each of these steps.

Time estimates are based on system capabilities, Technical Specification limits, and experience gained over past refueling outages.

1.

Borate the reactor coolant system (RCS) to 2000 ppm boron.

Using normal means of borating, the charging pumps, this will take a minimum of 5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />.

Rate of addition is approximately 10 gpm.

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'arch 27, 1979 Director of Nuclear Reactor Regulation 2.

Reduce the hydrogen concentration in the volume control tank to below 5 cc/kg.

If the level has been reduced to below 15 cc/kg while at power, approximately 3 "burps" would be required to reduce the level to below 5 cc/kg.

If plant cooldown is progressing while burping, then the burps are less effective due to the lower temperature.

Thus, more burps may be required.

The time estimate for this task is 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.

3.

Cool down the RCS to less than 140'F.

Based on the Technical Specification limit for cooldown rate of 100'F/hr, this will take at least 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />.

4.

Strip the reactor head and prepare for head lift.

This step is comprised of several individual tasks and requires at least 29 hours3.356481e-4 days <br />0.00806 hours <br />4.794974e-5 weeks <br />1.10345e-5 months <br />.

This time estimate includes the consideration that some tasks may be performed concurrently.

The tasks include a.

Control rod drive mechanism cooling duct removal b.

Missile shield removal c.

Earthquake bars removal d.

Head insulation removal e.

Cable tray and electrical connections removal f.

Acoustical and thermocouple connections removal g.

Inflatable seal ring installation 5.

Drain the RCS below the "flange level.

This step takes approximately 5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> and may be performed concurrently with the head stripping.

6.

Disassemble the instrument port conoseal.

This step takes approximately 5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> to perform.

7.

Detension the studs.

This step takes approximately 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> to complete.

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8. Lift the vessel head and flood the cavity.

This step takes ll hours to complete.

9.

Unlatch the control rod drive shafts.

This step takes 9 hours1.041667e-4 days <br />0.0025 hours <br />1.488095e-5 weeks <br />3.4245e-6 months <br /> to complete.

10.

Remove the upper internals package.

This step takes 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> to complete.

March 27, 1979 Director of Nuclear Reactor Regulation After completion of these steps, fuel can be handled.

The total time for these

steps, taking into account that some can be performed con-currently, is 106.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />.

No time has been included for reduction of the radioactivity level in the RCS.

Historically, this has taken between 48 and 60 hours6.944444e-4 days <br />0.0167 hours <br />9.920635e-5 weeks <br />2.283e-5 months <br />.

In order to maintain occupational exposures as low as reasonably achievable and to eliminate the requirement for respiratory protection equipment, RCS cleanup is normally performed prior to fuel handling.

Addition of this step brings the total time from shutdown to fuel movement to between 130 and 150 hours0.00174 days <br />0.0417 hours <br />2.480159e-4 weeks <br />5.7075e-5 months <br />.

Based on these

times, the assumption that fuel is not moved within 100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br /> of shutdown is conservative.

Very truly yours, Attachment

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Purification 8

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