ML19209A685

Forwards Response to IE Bulletin 79-21.Results of Review of Liquid Measuring Sys within Containment,Description of Sys So Employed & Description of Type of Ref Leg Encl

ML19209A685
Person / Time
Site:	Crystal River
Issue date:	09/17/1979
From:	Stewart W FLORIDA POWER CORP.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
NUDOCS 7910050196
Download: ML19209A685 (7)

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Power CORPORATsON Q is fC h h September 17, 1979 y 2 File: 3-0-3-a-4 {

Mr. J. P. O'Reilly .

Director U.S. Nuclear Regulatory Commission Office of Inspection and Enforcement Suite 3100 101 Marietta Street Atlanta, Ga 30303

Subject:

Crystal River Unit 3 Docket No. 50-302 Operating License No. DPR-72 I.E. Bulletin 79-21

Dear Mr. O'Reilly:

Enclosed is our response to I.E. Bulletin 79-21.

Please contact this office if you require any additional discussion concerning our response.

Very truly yours, FLORIDA POWER CORPORATION b

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W. P. Stewart Manager, Nuclear Operations /

WPSemhD77 cc: Director

, Division of Operating Reactors , _,

Office of Inspect' n and Enforcement U.S. Nuclear Regulatory Commission Washington, D.C. 20555

-1110 139 7930o50/ %

M4a5 General Office 320 Tn.rty-fourtn street soutn . P O Box 14042. St Petersburg. F onda 33733 e 813-8666ppyg

IE BULLETIN 79-21 RESPONSE FOR ALL PRESSURlZED WATER REACTOR FACILITIES WITH AN OPERATING LICENSE

1. Review the liquid level measuring systems within containment to determine if the signals are used to initiate safety actions or are used to provide post-accident monitoring information. Pt9 vide a description of systems that are so employed; a description of the type of reference leg shall be included, i.e, open column or sealed reference leg.

RESPONSE

B&W Level Instrumentation The liquid level men'suring systems for the steam generator, pressurizer and core flood tank have been examined. No safety actions are initiated by these measuring systems. These measuring systems are of the delta pressure, open column, uninsulated reference leg type with the exception of the core flood tank level. The core flood tank level has a dry reference leg that is not af fected by the containment environment.

The pressurizer water level is monitored to provide an indication of reactor coolant inventory and to control the makeup. The core flood tank water le vel is monitored to provide an indication of an adequate supply of water as required by Tech Specs. The steam generator water level is monitored to provide an indication and a control of the steam generator water inventory below 15% power. The level is monitore/ in three ranges; " Start-up", " Operating" and " Full Range."

Non-B&W Level Instrumentation WD-26-LT & WD-222-LT - RB Sump Level Transmitters: These measurements are important for leakage detection, LPI recirculation to the DH and BS systems, and post accident monitoring. These devices consist of displacer (float) activated torque tube, and, therefore, have no reference leg subject to the problem described in IE No. 79-21.

WD-131-LS - Reactor Building Sump Level Switch: This device is a Magnetrol float / magnetic switch mechanism used for alarm and sump pump contrcl. Since these functions are not safety-related and the devices do not have reference legs, they are not subject to the problem described in IE Bulletin No. 79-21. -

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WD-23-LT - RC Drain Tank Level Transmitter & WD-214-LS - RC Drain Tank Level Switch: These instruments both have Barton differential pressure measuring elements and share common impulse tubing lines.

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The reference leg is dry and measures the nitrogen pressu.re on top of the tank. Neither instrument performs a safety function nor is used for post-accident monitoring, therefore is not subject to the problem described in IE Bulletin No. 79-21.

Tibbs(IE79-21)D88 1110 140

2. On those systems described in Item 1 above, evaluate the effect of post-accident ambient temperatures on the indicated water level to determine any change in indicated level relative to actual water level. This evaluation must include other sources of error including the effects of varying fluid pressure and flashing of reference leg to stecm on the water level measurement. The results of this evaluation should be prdsented in a tabular form similar to Tables 1 and 2 of Enclosure 1.

RESPONSE

The effect of the reference leg temperature on the B&W 1evel measure-ment instrumentation systems identified above is listed in Tables 1 and 2. The errors listed have been maximized to account for varying fluid pressures and are applicable to all B&W operating plants.

Consideration has been given to boiling in the reference leg and the ejection of water from the reference leg due to the effervescence of soluble gases. These effects will be discussed for each component employing a water reference leg.

Steam generator level measurements are not significantly affected by the effervescence of soluble gases because there is insufficient soluble gas in the secondary system. For boiling to occur in the steam generator reference leg, the reference leg must experience high temperatures and almost complete depressurization. The repressuriza-tion of the steam generator will refill the reference leg and the errors would be no greater than those listed in the tables.

The pressurizer level could be affected by the effervescence of soluble gases. The ejection of water from a reference leg has been documented in BW-4689 and previously discussed with the NRC. A depressurization from 2000 to 1000 psi will cause an error of approximately 1%. Larger errors can exist for rapid depressurization to less than 600 psi, but under these conditions, pressurizer level is unimportant. However, supple entary instructions will be provided to make the operator aware of the possibility of pressuricer level indication errors following a rapid depressurization to pressures less than 600 psi. For boiling to occur in the reference leg, the system pressure must be below 300 psi and therefore need not be considered as discussed above.

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Tibbs(IE79-21)D88

TABLE 1 Correction to indicated water level for post-accident temperature ef fects of the steam generator operate level, steam generator full range level, pressurizer level and core flood tank level (for tanks with water refersnce legs).

Correction to Reference Leg Temperature Indicated Level (%)

(*F) of Full Span 100 2. 0 150 3.0 200 5.0 250 7.0 300 9. 0 350 12.0 400 15.0 NOTE: The increase in reference leg temperature causes the measured level to indicate higher than actual level.

d 1110 142 Tibbs(IE79-21)D88

TABLE 2 Correction to indicated water level for post-accident temperature ef fects of the steam generator start-up level. .

Correction to Reference Leg Temperature Indicated Level (%)

(*F) of Full Span 100 2.0 150 3. 0 200 5. 0

. 250 8. 5 300 12.0 350 16.5 400 21.0 NOTE: The increase in reference leg temperature causes the measured level to indicate higher than actual level.

Tibbs(IE79-21)D88

3. Review all safety and control setpoints derived from level signals to verify that the setpoints will initiate the ar. tion required by the plant safety analyses throughout the range of ambient temperatures encountered by the instrumentation, including accident temperatures.

Provide a listing of these setpoints. .

RESPONSE

No reactor protection system actions are initiated by these instruments; therefore, the error induced by the increase in the reference lag temperature need only be considered for post-accident monitoring. During post-accident monitoring, level indication alone is not relied upon but rather system temperature and pressures are used to assure adequate core cooling and to confirm the adequacy of the level indications.

Although not related to RPS actions, the pressurizer level instrumentation is used to deenergize the pressurizer heaters and therefore this action may have to be taken manually in the event of elevated containment temperatures. The low level pressurizer heater cutout is 40 inches.

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Tibbs(IE79-21)D88 1110 144

Y If the above reviews and evaluations require a revision of setpoints to en-sure safe operat ton, provide a description of the corrective action and the date the action tus completed. If any corrective action is temporary, sub-mit a description of the proposed final corrective action and a timetable for implementation. .

RESPONSE

The reviews and evaluations performed per Items 1, 2, and 3 of IE Bulletin No. 79-21 show that a revision of the setpoints is not required to ensure safe operation.

4. Review and revise, as necessary, emergency procedures to include spe-cific information obtained from the review and evaluation of Items 1, 2, and 3 to ensure that the operators are instructed on the potential for and magnitude of erroneous level signals. All tables, curves, or correction factors that would be applied to post-accident monitors should be readily available to the operator. If revisions to proce-dures are required, provide a completion date for the revisions and a completion date for operstor training on the revisions.

RESPONSE

B&W is preparing site instructions to deal with the general matter of level indication involving post-accident monitors under adverse environments. As soon as these instructions are received at Crystal River Unit 3 they will be incorporated in the emergency procedure and the operators will receive training on the revised procedures.

The procedure revisions and the operator training will be completed within five weeks of receipt of site instructions from B&W.

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g g i 110 145 Tibbs(IE79-21)D88