ML20012D771

Responds to NRC 900205 Comments on Util Discussing Tech Specs Applicable to Defueled Condition.Util Intends to Keep Area Radiation Monitor R15028 Functional at All Times.Spent Fuel Pool Bulk Temp Maintained at 80 F

ML20012D771
Person / Time
Site:	Rancho Seco
Issue date:	03/28/1990
From:	Keuter D SACRAMENTO MUNICIPAL UTILITY DISTRICT
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
AGM-NUC-90-095, AGM-NUC-90-95, NUDOCS 9003280353
Download: ML20012D771 (4)

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'is 0 - g uuo; SACRAMENTO MUNICIPAL UTILITY DISTRICT D 6201 S Street, P.o. Box 15830, Sacramento CA 95852 1830,(916) 452 3211 AN_ ELECTRIC SYSTEM GERVING THE HEART OF CALIFORNIA AGM/NUC 90-095-s U. S. Nuclear Regulatory Commission Attn: Document Control Desk-

-Hashington, DC 20555-g Docket No. 50-312 i"

Rancho Seco N. clear Generating Station License No..DPR-54 TECHNICAL SPECIFICATIONS APPLICABLE IN THE DEFUELED CONDITION RESPONSE TO NRC COMENTS l

- Attention:

George Knighton In an.NRC letter dated February 5, 1990 to Mr. Dan R. Keuter regarding the m

District's December 4,1989-letter which discussed Technical Specifications-

- (TS) applicable in the current defueled condition, Mr. Charles M. Trammell

-provided'three specific comments.

This letter constitutes the District's

. response to each of those comments:

CQltElll 1 Technical Specification 3.8.l'in Attachment 2 of your letter relates to area-radiation. monitor R15028 in the spent fuel pool building.

The present-specification requires the radiation monitor be operable only when moving fuel

in the spent. fuel storage area. Since there is 1) no criticality monitor-in the spent fuel pool,.2) a continuing decline in the number of on-site

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personnel available to monitor the spent fuel pool area, and 3) an apparent reduction in personnel training, it appears that maintaining that area radiation monitor functional, as a minimum, at all' times would be

- appropriate.

The monitor can serve as a t,ackup for spent-fuel pool level indication system and to monitor for potential fuel damage.

It is requested

-that you evaluate the benefit to safety provided by maintaining-this monitor-functional at all times and advise us o.f your results and any proposed actions.

RESPONSE

JIt._is the-District's current and future intention to keep R15028 functional at all times, with. implementation of appropriate compensatory actions in.the

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Levent the monitor becomes non-functional.

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. RANCHO SECo NUCLEAR GENERATING STATION D.14440 Twin Cities Road, Herald, CA 95638-9799;(209) 333-2935 A

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... AGM/NUC 90-095.

< George Knighton' COMEllL2 It is unclear what you are. proposing concerning the operation of the' HEPA/ charcoal-filtration systems.

Because the reactor and auxiliary buildings will continue to contain-substantial-radioactivity,-it would be appropriate to-maintain the HEPA filtration systems in a functional status.

It is requested

'_that you evaluate the need for maintaining the functionality of these systems' 1

and provide us with your results and any proposed actions.

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RESPONSE

The December 4,1989 letter lists TS applicable in the current defueled condition. Technical Specification 3.18 and 4.22 on that list include the current operability specifications for' Gaseous Radwaste Treatment Systems and associated actions.

Specifically, TS 3.18.4 requires the VENTILATION EXHAUST TREATMENT = SYSTEM to be OPERABLE. TS 4.22.4 states that-the installed VENTILATION EXHAUST TREATMENT SYSTEM is considered OPERABLE by meeting t

Specifications _ 3.18.1, 3.18.2, a d 3.18.3 (which contain specifications for doses, dose commitments, or dose rates related to gaseous effluent releases).

The District plans to continue to comply with these requirements to maintain L

the VENTILATION EXHAUST-TREATMENT SYSTEM "0PERABLE". even though the OPERABLE L

specification does not necessarily require the HEPA or charcoal filters be functional-unless the projected air dose exceeds the TS 3.18.4 limits.

Because the plant has been shutdown since 1989, iodine levels and particulate gamma emiters in the plant gaseous effluent (prior to treatment) have dropped l -

to essentially zero.

In the current mode, tritium is typically the only p

isotope present in gaseous effluent, and dose related calculations do not-l approach-the values in TS 3.18.1, 3.18.2, and 3.18.3.

As a result, the i

charcoal filtration systems will not-be maintained in a functional status, L

although the HEPA filters will be used at least for planned activities where

-the HEPA units would be desired or required.

The appropriate surveillance =

procedures will be:run when needed to ensure the units are fully functional.

CQtMQLL3 There.is_a concern that current procedures and training ray not adequately cover the area of maintaining spent fuel pool cooling and spent fuel pool-level following a postulated loss of offsite power event. _The current plant conditions do not match with the expected conditions during power operations (i.e., electrical alignment of the 480 V system with the breaker between the GM and TDI diesel generator busses closed.). A demonstration test of both equipment and procedures to' handle a loss of offsite power appears appropriate h

before formalizing changes.

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.a LGeorge Knighton AGM/NUC 90-095 1

RESPONSE

l-On December 15, 1989,- formal ' drawing and procedure changes reflecting current plant conditions, including use of the 3A/3A2 cross-tie, were issued for use.

Prior to issuance, the District implemented the following prudent actions:

1 The cross-tie between the 3A and 3A2 buses was incorporated into the' E

defueled plant configuration using our plant modification procedure. -DCP 89-0092 modified the affected plant drawings and included a Design Basis Report, load verification calculations, and a 10 CFR 50.59 determination review.

Previously, the-cross-tie was recognized as available only for maintenance purposes.

The affected casualty and operating procedures were extensively reviewed by the Operations and Technical Services Departments.

These procedures were then revised to reflect the cross-tie modification on defueled' emergency load requirements.

Special Test Procedure.(STP) 1312 was developed and successfully performed.

STP.1312 demonstrated that procedure revisions correctly aligned electrical buses and loads such that the cross-tie would handle 3

the-defueled emergency loads off of the 3A2 bus. STP.1312 did not require diesel operation or fast start.as the fast start test had been successfully conducted in October 1989, and the defueled emergency load is less.than the power operation emergency diesel load.

However, the cross-tie breakers were closed in, as were the required 3A2 loads.

Current measurements were then taken on the cross-tie to assure that the loading was within the cable rating.

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. Formal operating crew training was hdministered to the duty crews.

Subsequently, each on-coming crew was formally trained.

Additionally, on January 15, 1990, the District concluded STP.1313. This test was performed in order to establish the actual fuel pool heat-up rate should all cooling be interrupted. The test results indicate that the actual heat-up is approximately 40% slower than that calculated employing the assumptions of BTP APCSB 9-2.

In other words, it will actually take approximately 35 hours4.050926e-4 days <br />0.00972 hours <br />5.787037e-5 weeks <br />1.33175e-5 months <br /> for the temperature to rise from 110*F to 140*F as compared to the calculated time of just over 20 hours2.314815e-4 days <br />0.00556 hours <br />3.306878e-5 weeks <br />7.61e-6 months <br />.

'In practice, the Rancho Seco Spent fuel Pool bulk temperature is maintained at approximately 80'F with a water level nominally at EL 38'6".

Should trouble of any kind be experienced (e.g., failure of the A engine to start) operators will have more than 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> (as calculated) to either restore off-site power, or correct the A train trouble before pool temperature approaches 140*F from its normally maintained temperature of 80*F.

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George'Knighton AGM/NUC 90-095 q

As'in the original configuration, should we experience a total loss of off-site power in our present configuration, the spent fuel cooling pump will stop.

The A Bruce GM engine will be started either manually or by automatic fast start and pick up only its required auxiliaries (e.g., NRH, supply fans, etc.). The' operators will implement casualty procedure C.95 and will commence to manually close in'the A Decay Heat Removal System loads as well as the 3A to 3A2 cross-tie breakers, thereby restoring fuel pool cooling and providing any required essential HVAC. Based upon the preceding, the District is satisfied that current procedures, equipment and personnel training are adequate to assure that spent fuel pool cooling and water level are_ maintained in the event of a loss of off-site power.

Members of your staff with questions requiring additional information or clarification may contact Rita Bowser at (209) 333-2935. extension 4522.

Sincerely, Dan R. Keuter Assistant General Manager Nuclear cc:

J. B. Martin. NRC, Halnut Creek A. D'Angelo, NRC, Rancho Seco l

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