ML20247G547

Comments on Util 890104 & 0210 Responses to Generic Ltr 88-17 Re Expedited Actions in Response to Loss of Dhr. Response Generally Complete.Areas Where Response Incomplete Listed

ML20247G547
Person / Time
Site:	Fort Calhoun
Issue date:	05/18/1989
From:	Milano P Office of Nuclear Reactor Regulation
To:	Morris K OMAHA PUBLIC POWER DISTRICT
References
GL-88-17, TAC-69744, NUDOCS 8905310007
Download: ML20247G547 (5)

Text

_- -

'[

'o UNITED STATES g

NUCLEAR REGULATORY COMMISSION n

{

,E WASHINGTON, D. C. 20555 May 18, 1989 Docket No. 50-285 Mr. Kenneth J. Morris

' Division Manager - Nuclear Operations Omaha Public Power District 1623 Harney Street Omaha, Nebraska 68102 l

SUBJECT:

COMMENTS ON OMAHA PUBLIC POWER DISTRICT (OPPD) RESPONSE TO GENERICLETTER88-17,FORTCALHOUNSTATION(TACNO.69744)

The NRC has completed a review of your response, dated January 4 and February 10,.-

1989, to the NRC Generic Letter 88-17, Loss of Decay Heat Removal. With respect to the expeditious actions requested, it has been found that the intent of the Generic Letter has been met. Your overall response was generally complete and more detailed than others that have been reviewed to date. The responses were based en a plant specific report entitled " Engineering Evaluation of Fort Calhoun Station Loss of Shutdown Cooling at Mid-Loop Conditions", dated September 1988.

However, your responses to several areas were not sufficiently described that a full understanding of your actions could'be reached. Therefore, the following comments and observations are being provided such that you can assure l

yourself that the actions are adequate, i

a. While stating that a discussion of the Diablo Canyon event and training i

for specific mid-loop operation were conducted with operations personnel, shift technical advisors, and licensed management, the maintenance department was not specifically mentioned. It was intended that the I

action fr,clude all personnel who could affect reduced inventory operation.

b. Your, response stated that a review of Procedure A0P-19 determined that additional guidance was necessary concerning the evacuation of personnel from containment once boiling initiated when large opening in the RCS boundary exist. Since boiling could initiate within 30 minutes upon loss of residual heat removal and core uncovery within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />, personnel may need to leave containment or don protective gear 30 minutes after the loss of cooling because of steam inside containment.

c. For Item 5, relative to maintaining the RCS stable while the vessel head is installed and the RCS inventory is reduced, you state that a precaution will be incorporated if the pressurizer manway is not removed. This precaution is that a steam generator shall be available for decay heat j

removal and its nozzle dams not installed. A secondary side water level of 65% will be maintained in the steam generator. However, no provisions were addressed for steaming the secondary side for heat removal.

Of*l p.?P?3A8881$$8SN,gs P

P

/

1

w Mr. Kenneth'J. " Morris d. Wide range level instrument LI-197 was modified to provide a more accurate

. transmitter, an alarm function, and the ability'to provide an input to the plant computer for continuous readout and trending. You state that the instrument accuracy of LI-197 is +/- 1.98 inches, the computer level point accuracy is +/- 1.98.in. and the level alarm accuracy is +/- 1.7 in.

However, the accuracy of LI-197 indication on the control board was stated to be +7.16/-7.06 inches, which appears to be insufficiently accurate for use in the critical region where vortexing could occur.

e. You plan to install a second level instrument'during the 1990 outage which will have an alarm and input to the plant computer for trending. This narrow range level instrument will use the same instrument taps that exist for LI-197. Therefore, precautions will be necessary to preclude common errors causing loss of both instruments. Also, care will be needed to justify accuracy when comparing overlapping readings from both transmitters. '

The instrument loop accuracy was not stated for this narrow range indicator,

f. Fort Calhoun uses a visual level measuring system with tygon tubing. A walkdown of the tubing for kinks or loop seals is necessary prior to its placement in use and then on a daily basis during use.

g. Item 6 concerns the provision of two means' for adding inventory to the RCS that are. in addition to the pumps that are part of the normal RHR system.

In your response you made reference to the site specific analysis in which '

eleven cases of loss of shutdown cooling were analyzed. This provided the basis'for the upgrade of Procedure A0P-19. The. analysis indicated that with only the pressurizer vent removed, the countercurrent steam flow from.

the reactor through the hot leg and pressurizer surge line was significant enough to prevent any injected makeup water from the pressurizer spray line to return through the~ surge line. In addition, the steam velocity would be sufficient to prevent the spray droplets from falling, and instead they would be carried up through the pressurizer and out the vent path.

Your. calculations using cold leg injection and removal of the pressurizer valves and the pressurizer manway indicate that it would be possible to cool the reactor and prevent core uncovery. The equilibrium reactor vessel pressure was given as 40 psia and 16 psia for cases 4 and 7, respectively.

Since you have indicated that a pressure of 40 to 65 psia is needed to challenge the nozzle dams, the values of equilibrium pressure appear to be safe. Your conclusions in the analysis stated that a large RCS vent, e.g.

pressurizer manway or reactor vessel head, would be available at mid-loop conditions. Otherwise, the RCS integrity would be established or maintained 1

and the steam generator heat removal made available.

In your Reference No.

j 4 you state that these directions are currently published in 01-RC-1. The Staff would also prefer that, if possible, a means be found to utilize the pressurizer spray for hot leg injection because of the restriction in the size required for the cold leg opening when cold leg injection is utilized.

This may be possible if other suitable vent openings other than in the pressurizer are available. An alternative hot leg injection path may exist if makeup water could be injected in the RHR drop line, as discussed during the October 1988 site visit.

4

l Mr. Kenneth J. Morris The expeditious actions that you have described in your submittal are an interim measure to achieve an imediate reduction in the risk associated with operation with reduced reactor coolant system inventory. These will be supplemented and, in some cases, replaced by programmatic enhancements. Your responses to the expeditious actions and the programmatic enhancements will be audited by the NRC at a later date.

Furthermore, we request that you consider the above comments and take whatever action you find appropriate. However, a response to these observations is not required at this time.

Sincerely,

/5/

Patrick D. Milano, Project Manager Project Directorate - IV Division of Reactor Projects - III, IV, V and Special Projects Office of Nuclear Reactor Regulation cc: See.next page DISdIBUTION tEocket File NRC PDR Local PDR PD4 Reading G. Holahan L. Rubenstein F. Hebdon P. Noonan P. Milano 0GC-Rockville E. Jordan ACRS (10)

PD4 Plant File 1

DOCUMENT FLAME:

FT CALHOLN GL 8817 RESPONSE

{

i 1

1 PNoonab.(-

PD4/LA PD4/FM PD4/D PMilano:bj FHebdon gji.

05/g/89 05/it/89 05/%/89 i

-.__._____.__m__.

4 l

l l

Mr. Kenneth J. Morris The expeditious actions that you have described in your submittal are an interim measure to achieve an immediate reduction in the risk associated with operation with reduced reactor coolant system inventory. These will be supplemented and, in some cases, replaced by programmatic enhancements. Your responses to the expeditious actions and the programmatic enhancements will be audited by the NRC at a later date. Furthermore, we request that ycu consider the above connents and take whatever action you find appropriate. However, a response to these observations is not required at this time.

Sincerely, M3bt Patrick D. Milano, Project Manager Project Directorate - IV Division of Reactor Projects - III, IV, Y and Special Projects Office of Nuclear Reactor Regulation cc: Sec next page

_m____

j p*.-

l E

Mr. :Kenneth J. Morris -

- Fort Calhoun Station l

L Omaha Public Power District Unit No. 1 Cc'

]

Harry H. Voigt, Esq.

1 LeBoeuf, Lamb,.Leiby & MacRae

- 1333 New Hampshire Avenue, NW Washington, D.C.

20036 Mr. Jack Jensen, Chairman Washington County Board of Supervisors Blair, Nebraska 68008 Mr. Phillip Harrell, Resident Inspector U.S. Nuclear Regulatory Commission P. O. Box 309 Fort Calhoun, Nebraska 68023 Mr. Charles C. Brinkman, Manager Washington Nuclear Operations Combustion Engineering, Inc.

12300 Twinbrook Parkway, Suite 330 Rockville, MD 20852

- Regional Administrator, Region IV U.S. Nuclear Regulatory Commission

-. 0ffice of Executive Director for Operations 611 Pyan Plaza Drive, Suite 1000 Arlington, Texas 76011 Harold Borchert, Director Division of Radiological Health Department of flealth 301 Centennial Mall, South P.O. Box 95007 Lincoln, Nebraska 68509 W. G. Gates, Manager Fort Calhoun Station P. O. Box 399 i

Fort Calhoun, Nebraska 68023 P

4

_