ML20112J694

Statement of Matl Facts as to Which There Is No Genuine Issue

ML20112J694
Person / Time
Site:	Perry
Issue date:	01/14/1985
From:	Huber E SHAW, PITTMAN, POTTS & TROWBRIDGE
To:	Atomic Safety and Licensing Board Panel
Shared Package
ML20112J676	List: ML20112J668 ML20112J694 ML20112J726 ML20112J742 ML20112J753
References
OL, NUDOCS 8501180349
Download: ML20112J694 (7)

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a C7. T rr' UNITED STATES OF AMERICA . : -- e .,

NUCLEAR REGULATORY COMMISSION

'/ N !22 BEFORE THE ATOMIC SAFETY AND LICENSING BOARD ' -

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, ,y In the Matter of )

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THE CLEVELAND ELECTRIC ) Docket Nos. 50-440 ILLUMINATING COMPANY, BT AL. ) 50-441

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(Perry Nuclear Power Plant, )

Units 1 and 2) )

APPLICANTS' STATEMENT OF MATERIAL FACTS AS TO WHICH THERE IS NO GENUINE ISSUE TO BE HEARD ON ISSUE 14 Pursuant to 10 C.F.R. 5 2.749(a), Applicants state, in support of their Motion for Summary Disposition of Issue 14 in this proceeding, that there is no genuine issue to be heard with respect to the following material facts:

1. Issue 14 states that in-core thermocouples Thould be used at Perry Nuclear Power Plant ("PNPP") to detect inadequate core cooling ("ICC"). ASLB Memorandum and Order, October 29, 1982.

2. Generalized (i.e., core-wide) ICC can only occur at PNPP if the water le"- in the core has dropped below the top of the active fuel, which is approximately 18 feet below normal water level. Localized overheating (i.e. overheating of a sin-gle fuel bundle) due to blockage of cooling water can occur even if the reactor core as a whole is adequately cooled.

8501180349 B50114 PDR ADOCK 05000440 0 PDR

Affidavit of Charles B. Johnson (" Johnson Affidavit"), 11 6, 7.

As used herein, "ICC" refers to generalized ICC.

3. The principal method by which PNPP can detect ICC is through the use of eight redundant variable legs, each of which is connected through one or more differential pressure sensors to a reference leg, to measure the water level in the reactor above the top of the active fuel, and three additional variable legs to measure water level from the top to the bottom of the active fuel. Id. at 11 8-9.

4. PNPP can detect localized overheating through the use of high steamline radiation monitors and off-gas monitors. The steamline radiation monitors can detect the release of fission products within 13 seconds of occurrence; the off-gas monitors can do so within 2 minutes of occurrence. These systems can also be used to detect generalized ICC. Id. at 11 10, 11.

5. Industry experience has demonstrated that water level measurement systems used in PNPP-type Boiling Water Reactors

("BWRs") are highly reliable. Id. at 1 13.

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6. Studies performed by S. Levy, Inc. demonstrate that l two situations, caused by drywell overheating, can result in inaccurate water level measurements in PNPP-type BWRs. Id. at

, 1 13. S. Levy, Inc. made three recommendations which are ap-i plicable to PNPP for eliminating the effects of drywell i'

overheating. Id. at 1 14.

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7. S. Levy, Inc.'s recommendations were first, to mini-

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mize the vertical drop in the reference leg piping in the drywell; second, to make the vertical drops of associated ref-

! erence and variable legs approximately equal; and third, to lo- ,

cate the flow-rastricting orifices in the reference legs as close to the drywell penetrations as possible. Id.

8. The NRC Staff has evaluated the recommendations of S. Levy, Inc., and has indicated'that these recommendations are adequate to address the Staff's concern regarding the potential for inaccurate water level measurement at PNPP. Id. at 1 30.

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9. Applicants have modified the design of PNPP's water-level measurement system in accordance with the recommen-

! dations of S. Levy, Inc. to eliminate the effects of drywell overheating. Affidavit of Frank Stead, 11 6-8. Applicants have changed the construction of PNPP's water level measurement

, system to implement these design modifications. Affidavit of Gary R. Leidich, 1 3.

10. Even if multiple simultaneous instrument failures ,

were to occur in PNPP's instruments used to measure water level j above the core, no danger of core uncovery would be posed, nor would unusual operator action be required. Johnson Affidavit, 1 15. .

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< 11. Industry expbrience shows that most instances of er-roneous water level measurement are attributable to the use of 1

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mechanical, rather than analog, level indication equipment.

PNPP uses analog level indication equipment. 'Id. at 1 16.

12. Design and function limitations dictate that the only feasible in-core location for thermocouples at PNPP would be -

inside the Local Power Range Monitor ("LPRM") tubes, which are located between fuel bundles. Id. at 11 20-24.

13. In-core thermocouples are virtually unable to detect the approach of ICC because the fuel rods must be partially uncovered and significant overheating must occur before thermocouples react sufficiently to distinguish ICC from normal temperature variations. Id. at 1 26.

14. During a relatively slow loss-of-coolant accident

("LOCA"), thermocouples would not indicate ICC until approxi-mately 52 minutes after water level first started to drop. Id.

During a relatively rapid LOCA, water level would be dropping so quickly that thermocouples would not react soon enough to provide warning prior to ICC, and remedial action would have been automatically initiated by PNPP's emergency core cooling systems. Id. at 1 32.

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15. In-core thermocouples at PNPP could generate ambigu-ous readings during ICC because the activation of emergency core cooling systems (s.uch as high pressure core sprays)aor pressure relief valves would wet the thermocouples, causing them to indicate lower temperatures than actually exist in the reactor core. Id. at 1 27.

16. As long as the LPRM tubes are covered with water, thermocouples in them will not detect localized overheating caused by flow blockage inside neighboring fuel channel boxes.

Id. at 1 28. ,

17. In-core thermocouples can contribute to localized overheating of fuel bundles by interfering with heat transfer to, and the flow of, cooling water. In order to detect local-ized overheating reliably at PNPP, 748 thermocouples (one per fuel bundle) and 748 pressure tubes to house them would be re-quired. Installation of thermocouples in these numbers is im-practicable because the additional pressure tubes would not only contribute to localized overheating, but would require nu-4 merous additional penetrations of the reactor vessel. Id. at i

1 28.

18. The addition of an unambiguous ICC detection device at PNPP would reduce the likelihood of a core melt accident due to a failure to detect ICC by only about 0.34 events /million reactor years. Since in-core thermocouples are not unambiguous l in all situations, and can contribute problems to a water level measurement system, their installation at PNPP would reduce the I likelihood of a core melt accident by less than that amount.

Id. a' 1 30.

19. As indicated in Regulatory Guide 3.97, Rev. 3, Sup-plement 1 to NUREG-0737, and Generic Letter No. 84-23, the NRC Staff no longer recommends that thermocouples be used in BWRs l'.

I to detect ICC. OCRE's reliance on the NRC Staff's former rec-ommendation is therefore no longer a valid basis for the in-stallation of in-core thermocouples at PNPP. Id. at 1 30.

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20. Analyses of thermocouple response time performed by both S. Levy, Inc. and Battelle Labs indicate that in-core thermocouples must be uncovered before they can detect and re-l spond to impending ICC. The more rapid response reported by l

Battelle (1.5 winutes after the thermocouple is uncovered vs.

13 minutes as calculated by S. Levy, Inc.) is traceable to the I high decay heat Battelle assumed and the assumed absence of convective steam cooling. Id. at 11 31-32.

21. The analyses of both S. Levy, Inc. and of Battelle l Labs show that the core will be seriously overheated by the

time thermocouples are able to indicate ICC. The Battelle I

i analysis is thus not a valid basis for OCRE's contention that

, in-core thermocouples should be installed at PNPP. Id.

22. Extensive analyses by General Electric and other in-vestigators demonstrate that steam explosions will not occur in

{ BWRs in which ICC is taking place. Id. at 1 35. OCRE's reli-ance on the postulations of Dr. Webb (regarding the possibility of a propagating core-melt accident caused by steam explosions) is thus not a valid basis for the contention that in-core thermocouples should be installed at PNPP. Id.

23. Existing water level measurement systems at PNPP pro-vide an accurate and reliable means of detecting ICC. Instal-lation of in-core thermocouples at PNPP will not significantly improve the ability of PNPP's existing instrumentation to de- -

tect and respond to ICC, and will contribute to ambiguities and problems of localized overheating which PNPP's current system does not possess. Id. at 1 37.

Respectfully submitted, Jay E. Silberg, P.C.

Evans Huber SHAW, PITTMAN, POTTS AND TROWBRIDGE 1800 M Street, N.W.

Washington, D.C. 20036 (202) 822-1000 Dated: January /4,1985 l

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