ML20235G633
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UNITED STATES ATOMIC ENERGY COMMISSDN i
l NORTHERN STATES POWER COMPANY Monticello Nuclear Generating Plant Ibcket No. 50 263 REQUEST FOR AUTHORIZATION OF A CHANGE IN TECHNICAL SPECIFICATI0E OF APPENDIX A PROVISIONAL OPERATING LICENSE NO. DPE-22 (Change Request No. 4) l Northern States Power Company, a Minnesota corp: ration, requests authorization for changes to the Technical Specifications as shown on the attachments labeled Exhibit A and Exhibit B.
Exhibit A describes l
the proposed changes along with reasons for change. Ixhibit B is a copy of the Technical Specifications marked up to indicate the proposed changes.
1 This request contains no restricted or other defense information.
i NORTHERN STATES POWER CpMPANY By Arthur V. Dienhart Vice Presiden -Engineering On this / M day of aj
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,1972, befo e me a notary public in and for said County, perpfynallygppeared Arthur V. Dienhart, Vice President. Engineering, and%eing nrst duly sworn acknowledged that he is authorized to execute this document in behalf of N:rthern States Power Company, that he has read it and knows the contents thereof, that to the best of his knowledge, infomation and belief, the statements made in it ar/rueandthat t
t is not interposed for delay.
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J JcIhn J Egfith
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/ Notary IV blic, Hennepin County, Minnesota u
JCHN J. SMITH Hotny Pub:!c, ibane,,in Couniy, Wnne. 's My Comm!nion I:.p'res March 3,19;'4 8709300129 870921 PDR FOIA ej / '/
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. / ;, _,. o MEN 187-111 PDR Cn
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EXHIBIT A MONTICELLO NUCLEAR GENERATING PLANT DOCKET NO. 50-263 PROPOSED CHANGES TO TECHNICAL SPECIFICATIONS APPENDIX A 0F PROVISIONAL OPERATING LICENSE NO. DPR-22
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Pursuant to 10 CFR 50 59, the holders of the ubove mentioned license hereby propose changing Section 3 5.C, Besidual Heat Removal (RHR) Service Water' System of Appendix A, Technical Specifications of Provisional Operating License DPR-22 as follows:
On Page 102, Section 3 5.C.4, ".... against a head of 550 feet,",
should be changed.to read, ".... against a system head of at least 500 feet."
Reason for change:
The wording of the present Technical Specification is more restrictive than originally intended.
It has been established through periodic surveillance tests and additional testing pursuant to the RHR service water pump lov head condition reported in our letter of July 3,1972 that the operating margin available to meet the current RHR service water pump head requirement is not adequate. ' Ibis condition arises basically from the pump performance charac-teristic which, as demonstrated on our system, does not confort with the manufacturer's certified head-capecity characteristic, and the allec,mnce of inadequate operating margin in the original selection of the Technical Spec-ification limit.
Basis for change:
The safety design basis of the RHR service water pump head requirement was reported to you in our July 3,1972 letter. As we have reported, the current Technical Specification requirement is based in part upon the manufacturer's j
rating (3500 gpm at 626 feet).
The maximum demand on the RER service water pump would be approximately 480 feet.
The individual contributions to this value are summarized as follove:
315 feet Shell side pressure; measured at heat exchanger inlet,1 RER pump @ 4000 gpm 62 feet Flov losses on RHR service water system; difference in measured values discharge prebsure and pressure at beat exchanger outlet (tube side) @ 7000 gpm 57 feet Primary containment pressure following a LOCA h6 feet Required differential pressure - tube to shell 480 feet TOTAL Y
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. This situation occurs when only one of the two redundant RHR pumps is cperating (minimizing losses on the shell side),. delivering h000 gpm, and both RHR ser-vice veter pumps are operating (maximizin6 flov losses on the tube side).
When the RHR service water is brought into service following a loss of coolant accident, a ten minute period is alloted in the design analysis to account for operator response time in limiting the containment transient by shifting to
!,he RHR containment cooling mode. The containment pressure at this point is approximately 22 psig. We have, in this case, conservatively taken the con-tainment pressure at 25 psig, thenby covering any situation where the opera-tor might respond in less than 10 minutes.
The containment cooling mcde of the RHR system serves to limit the long term containment pressure and temperature transient. Since torus water is being recirculated in this mode, the service water pressure is kept higher than the primary side pressure to preclude leakage to the open cycle service water sys-tem. A minimum differential pressure of 20 paid is required.
The proposed change to the Technical Specification vould provide a minimum p_u;:;p discharge pressure of 500 feet (216 psi) measured in accordance with the definitions of the ASME Pump Test Code. This vould result in a pressure on the RER service water side of the heat exchangers more than 20 psi greater than the RHR primary side, thus forcing water into the torus in the unlikely event of a heat exchanger tube leak. The 500 foot limit (i.e. 480 feet plus 20 feet margin) would be sufficient to assure adequate head to meet all system design bases and contingencies and, at the same time, leave sufficient mar-gin to assure the operating and testing flexibility important to plant safety.
This amendment to the Technical Specification is proposed on the basis of our experience with the RHR service water system and our complete satisfaction that a reduction in the limit is both tolerable and desirable.
In our opin-ion, this proposed change lessens neither the plant's safety nor reliability from a design or operational standpoint. Specifically, there 1s no increase in the probability of, no increases in the possible consequences of, or no creation of a credible p2tbability of an accident or equipment malfunction different from those previously evaluated in the FSAR. The proposed change' has been reviewed and approved by the Monticello Operations Committee and Safety Audit Committee.
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