ML20135E872

Safety Evaluation Supporting Amend 74 to License DPR-54

ML20135E872
Person / Time
Site:	Rancho Seco
Issue date:	09/09/1985
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20135E860	List: ML20135E857 ML20135E867 ML20135E872
References
TAC-63030, NUDOCS 8509170061
Download: ML20135E872 (3)

Text

,

o UNITED STATES y

g 2

NUCLEAR REGULATORY COMMISSl_ON o

5 E

WASHINGTON, D. C. 20555 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATf0N SUPPORTING AMENDMENT NO. 74 TO FACILITY OPERATING LICENSE NO. DPR-54 SACRAMENTO MUNICIPAL UTILITY DISTRICT RANCHO SECO NUCLEAR GENERATING STATION DOCKET NO. 50-312 I.

INTRODUCTION A.

DESCRIPTION OF PROPOSED ACTION The proposed action would amend Section 4.6.6.8 of Appendix A of the facility Technical Specifications. This section specifies the testing requirements for the pressurizer heaters that are capable of being energized from emergency power supplies in the event of a loss-of offsite power.

Instead of the present requirement that power be transferred from the "... normal to the emergency power supply..."

and the pressurizer heaters then be energized; the proposed change would provide that the power capability be demonstrated by using the Nuclear Service Bus to energize the pressurizer heaters.

8.

BACKGROUND INFORMATION One of the recommendations of the TMI-2 Lessons Learned Task Force (NUREG-0578) was the provision of emergency power for the number of

~

pressurizer heaters required to maintain natural circulation conditions in the event of a loss of offsite power.

In addition, the NRC's Generic Letter of July 2,1980, forwarded model technical specifications which prescribed appropriate means for testing this group of pressurizer heaters and requested licensees to apply for amendment of facility technical specifications to incorporate these model technical specifications. The Sacramento Municipal Utility District (the licensee) responded to this request on October 8, 1980, by proposing technical specifications which were substantially identical to the model. These were subsequently approved by the NRC on March 27, 1981.

By letter dated October 29, 1984, the licensee requested amendment of these specifications to permit a change in the method of verifying heater operability. This evaluation addresses,the acceptability of this rec,uest.

8509170061 850909 r

II. EVALUATION PDR ADOCK 05000312 P

PDR Prior to the accident at TMI-2, there was no requirement that pressurizer heaters be capable of being energized from emergency power sources.

These loads, therefore, were typically served by non-Class IE electrical

\\

i l

s

. l i

buses. With adoption of this requirement, licensees were required'to i

develop new procedures or implement modifications to permit these loads to be energized by Class IE sources - particularly the emergency diesel i

generators. In addition, the requirement led to the incorporation of i

present specification 4.6.6.8 which follows the model technical specification and states:

3 i

"The emergency power supply for the pressurizer heaters shall be demonstrated OPERABLE at least once per 18 months by transferring power from the normal to the emergency power supply and energizing the heaters."

The licensee states they have performed this verification regularly by starting the diesel generators and energizing the pressurizer heaters i

from this power source. The licensee also notes, however, that their method for complying with the TMI requirement was to modify the electrical distribution system so the required number of pressurizer j

heaters would always be energized from redundant Class IE buses. Thus, no special' switching procedures would be required. The licensee now observes that with this modification, no useful purpose is served by the present practice of starting the diesel generators in order to energize the pressurizer heaters. The licensee baser this statement on the fact that the designated groups of pressurizer he;ters are always served by the Class IE.4uclear Safety Buses. Thus, as far as energizing these heaters is concer.*ad, it is immaterial whet'.ar the Buses are supplied by the diesel generators or from offsite power. As long as,the Nuclear Service Buses can be powe md from either of these sources, the heaters can be energized. As a result of these considerations, the licensee has proposed to revise specification 4.6.6.B to read as follows:

"The power supply for the pressurizer heaters shall be demonstrated OPERABLE at least once per 18 months by using the Nuclear Service Bus to energize the heaters."

j Regarding this request, we note the licensee's implementation of the i

NUREG-0578 recommendation concerning power supplies for pressurizer l

heaters (Item 2.1.1) was reviewed by the NRC staff and approved by NRC letter dated May 1, 1980. We also note the installed modification and associated procedures were reviewed and found acceptable, as documented in NRC Inspection Report 50-312/80-23, dated August 13, 1980.

i i

As for the effect of the change in test methods, our review of the licensee's electrical drawings confirms that the designated pressurizer heaters are pennanently connected to the respective Nuclear Servics Buses. We therefore agree with the licensee that the pressurizer heaters will be capable of being powered whenever the Nuclear Service Bus (s are 4

1 energized - regardless of the source of power. Thus,. since the so'le purpose of the onsite emergency power system is to provide power to the Nuclear Service Buses, and this function is already confirmed by other l

tests, there does not appear to be any safety benefit to be derived from requiring the licensee to start the diesel generators merely for the i -

t

- ~.. - - -..

.~~

- purpose of energizing the pressurizer heaters.

Indeed, such a requirement could be counter-productive by unnecessarily increasing diesel generator wear. Accordingly, we conclude the change requested by the licensee will not reduce the present level of safety and is acceptable.

III. ENVIRONMENTAL CONSIDERATION This amendment involves a change in a surveillance requirement. We have determined that the amendment involves no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure. The Commission has previously issued a proposed finding that this amendment involves no significant hazards consideration and there has been no public comment on such fir. ding. Accordingly, this amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22 (c)(9). Pursuant to 10 CFR 51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the issuance of this amendment.

IV. CONCLUSION We have concluded, based on the considerations discussed above, that (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, and (2) such activities will be conducted in compliance with the Commission's regulations, and the issuance of the amendment will not be inimical to common defense and security or to the health and safety of the public.

Date:

September 9,1985 Principal Contributor:

G. Zwetzig i

\\-

1 l

_,_