Technical Memo -- Babcock & Wilcox
The Babcock & Wilcox Company
Power Generation Group
Distribution
From: J.J. Kelly, Plant Integration
Subj: Customer Guidance on High Pressure Injection Operation
Distribution
Karrasch
E.W. Swanson
R.J. Finnin
B.M. Dunn
D.W LaBelle
Elliott
D.F. Hallman
Our sophisticated high-pressure injection system can prove challenging to our customers.
A number of our customers have reported problems when operating the high-pressure injection system. Their reports indicate that our customers may not have all the information that they need to safely use the systems. These situations suggest that our customers don't understand when or how they can safely shut down following an accident that requires the continuous operation of the high-pressure injection system.
To illustrate this problem, two examples of recent events at the Toledo site are provided below.
On September 24, 1977, after depressurizing due to a stuck open electromatic relief valve, high-pressure injection was automatically initiated. The operator stopped HPI when pressurizer level began to recover, without regard to primary pressure. As a result, the transient continued on with boiling in the RCS, etc.
In a similar occurrence on October 23, 1977, the operator bypassed high-pressure injection to prevent initiation, even though reactor coolant system pressure went below the actuation point.
These incidents could have been avoided if our customers had more knowledge about use of the system, and if they had ready access to a reference providing simple, easy to understand operational guidance.
I recommend that we provide the following guidelines -- in writing -- to our customers:
a) Do not bypass or otherwise prevent the actuation of high/low pressure injection under any conditions except a normal, controlled plant shutdown.
b) Once high/low pressure injection is initiated, do not stop it unless: Tave is stable or decreasing and pressurizer level is increasing and primary pressure is at least 1600 PSIG and increasing.
I believe that providing these guidelines help protect our customers from exacerbating risk during and immediately after an accident. Further, provision of these guidelines is a prudent risk management activity for the company.
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