Basis for Venting Capacity

I have e-mailed the following to NRC today:

The following paragraph is from page 1 of  Basis for Venting Capacity in Order EA-13-109, “Order to Modify Licenses with Regard to Reliable Hardened Containment Vents Capable of Operation Under Severe Accident Conditions” (ML13221A011):

Over the years a number of studies have been completed related to generation of energy within

the reactor core and subsequent decay heat once the reactor has shutdown. The American

Nuclear Society Standard (ANS) 5.1 (Reference 1) which was approved by the ANS standards

committee in August 1979 provides a method to calculate decay heat power in light water

reactors. In 1980’s, the NRC sponsored further studies under a program known as Severe

Accident Consequences Mitigation. In one of the reports, NUREG/CR-3908 (Reference 2),

Figure 2-1 provides decay heat rate and heat accumulation curve with time. It shows that after

3 hours, the decay heat is about 1 % (values shown in that figure were based on 3440 MWT

BWR plant at 80 % power, but they show power at or below the 1% of thermal power history

value at 3 hours). Generic Letter 89-16 (Reference 3) related to installation of hardened wetwell

vents was issued in September 1989 and stated that the system installed by Boston Edison

Company at the Pilgrim Nuclear Power Station and associated analysis was acceptable. The

design analysis included a vent design objective of venting approximately 1 % of decay heat for

a 56 psi saturated steam conditions in the torus. In July 1996, in Information Notice (IN) 96-39

(Reference 4), the NRC staff provided additional clarification in selecting input parameters for

estimating decay heat using methodology provided in ANS 5.1. The IN also included results

using various available computer codes (MELCOR, RELAP, TRAC, etc...). On the international

level, Swiss standard HSK-R-40/d (Reference 5) issued in March 1993 noted in Section 3.2 that

the design capacity should be based on a guiding value for steam production of 1% of the

thermal reactor power. References 6 and 7 provide additional information on decay heat

estimates and compares different methods and results.

The following sentence from the above paragraph is erroneous: “The design analysis included a vent design objective of venting approximately 1 % of decay heat for a 56 psi saturated steam conditions in the torus.”

The NRC should issue a corrected version of ML13221A011 that removes the above erroneous sentence.

That corrected version of ML13221A011 should clarify reference 3 by adding ML13017A234 or ML031140220 or both.  As it is now, the reference is incomplete.   3. Generic Letter 89-16, “Installation of a Hardened Wetwell Vent.” September 1, 1989.

In addition, that corrected version of ML13221A011, should replace the erroneous date on page 3 with the correct date.

Finally, the corrected version should acknowledge that the original version was produced in response to an e-mail inquiry by Robert H. Leyse, bobleyse@aol.com, to OPA.Resource@nrc.gov on 7/25/2013.  The corrected version should also acknowledge that the corrections were requested by Robert H. Leyse, bobleyse@aol.com,  via this e-mail dated 10/14/2013.

Robert H. Leyse   bobleyse@aol.com