ML19031B393

Furnishing Information Regarding Reactor Pressure Vessel Supports Asymmetric Cavity Pressure Loading

ML19031B393
Person / Time
Site:	Salem
Issue date:	10/29/1976
From:	Mittl R Public Service Electric & Gas Co
To:	Kniel K Office of Nuclear Material Safety and Safeguards
References
Download: ML19031B393 (2)

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Public Service Electric and Gas Company 80Park Place lr-:Jewar~,<t:J.'LJ./07101 Phone 201/622-7000 October 29, 1976 Director of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, D. C. 20555 Attention: Mr. Karl Kniel, Chief Light Water Reactor Gentlemen:

REACTOR PRESSURE VESSEL SUPPORTS ASYMMETRIC CAVI~Y PRESSURE LOADING NO. 1 AND 2 UNITS SALEM NUCLEAR GENERATING STATION DOCKET NOS. 50-272 AND 50-311 Reference.: (1) Letter to D. B. Vassallo (USNRC) from R. L. Mittl (PSE&G) dated March 1, 1976, this subject.

In the Reference l letter, the status of the Salem plants regarding the asymmetric cavity loading concern was discussed. Specifically, it was stated that motion limiters (bumpers) had been installed on the reactor coolant loop piping in order to limit postulated break sizes and hence reduce resulting forces on the reactor vessel supports. Results of analyses to conclusively demonstrate continued reactor pressure vessel support integrity were expected in October 1976.

The aforementioned analyses have been actively pursued. Input data for the three phases of the force generation calculation (i.e., asymmetri.c cavity forces, loop piping forces, and reactor vessel internals) have been generated and preliminary runs of computer calculations of the asymmetric cavity forces have been made. Results obtained to date con-firm the confidence expressed in our Reference 1 letter as to the ade-quacy of the Salem reactor vessel supports. Formal calculation of the other two compo11ents of the force calculation, time history superposition, or detailed component evaluations have not yet been made.

As you are aware, the subject concern has been the object of substantial review and discussion within both the NRC and the*nuclear industry. A dichotomy of approach has arisen, such that some plant owners are pur-

• suing detailed analytical justification of their designs, while others, convinced of the justifiability of their designs, are proposing a program of augmented In-service Inspecttons as an active rather than passive step in addressing the subject concern.

Tho Energy PHople

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Dir. of Nuc. Reactor Reg. 2 10/29/76 Public Service has been reviewing both approaches. Inasmuch as the afore-mentioned preliminary analysis continues to provide confidence that the Salem supports are adequate, we believe that.an augmented ISi Program should be considered as an alternate to further analytical treatment. We are placing emphasis on defining an augmented ISi Program which could be adopted following NRC acceptance of the augmented inspection alternate as proposed by the nuclear industry.

Very truly yours,

~~(:f General Manager - Projects Engineering qnd Construction

. Department kI;,,

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