Emergency Operating Procedure

EOP 6 Rupture in Buffer Seal System Revision 2 2/6/64

A. Symptoms

B. Immediate Action

C. Follow-Up Action

D. Discussion

The rupture postulated here is a large leak in the buffer seal system. Leaks in this system could be classified in two ways: those occurring in the piping inside the containment vessel, and those occurring in the piping outside the reactor space. High pressure is normally subjected to the piping from the discharge of the buffer charge pumps. The worst type of leak could be one between the check valve SL-5V and the seals; this rupture would be comparable to that discussed in EOP #1 for primary system rupture. For such a rupture the leakage rate would be something less than 10 gpm per seal. This condition would cause the primary system pressure to drop. The reactor should be scrammed as soon as possible if not done so automatically.

The lower O-rings which are made of Buna-N material are the only portion of the seal assembly which is susceptible to damage when the buffer seal charge pumps are shut off. These O-rings depend on the seal water to keep them below 350F. Sustained exposure in excess of 350F for periods of six to eight hours cause them to harden and reduce their effectiveness as seals.

As soon as the rupture can be isolated and repaired, the primary system purification and buffer seal systems should be started again. The operator should closely observe the operation of the system, particularly the flow rates into the buffer seals and the return from the seals. The primary purification letdown flow rate should be observed also. For this accident, it is expected that there will be an increase in seal leakage inward to the primary system due to hardening of the O-rings. My text copyright 2020 Tommy Johnson, all rights reserved. I believe the Savannah documentation is property of MARAD or the US government.