MDEP Codes and Standards Working Group

CSWG’s Initiative to Harmonize
Nuclear Pressure-Boundary Codesand Standards

MDEP Codes and Standards
Working Group’s (CSWG’s) GoalAchieve harmonization of code requirements
for the design and construction of pressureretaining components in order to:– improve the effectiveness and efficiency ofregulatory design reviews,– increase the quality of safety assessments,– strengthen each regulator’s ability to makesafety decisions

Why Do We Need Harmonization?
• Construction of NPP components has become aglobal venture• Many questions arose in the use of codes andstandards– Is it practical and safe to construct pressure-boundary
components for a nuclear power plant using codes andstandards from different countries?
– Is there a way to harmonize the rules of different
countries’ codes and standards?
– How different are each country’s codes and standards?

Model for Harmonization of Code Requirements

Differences today

Equivalenttechnical
administrative

Different

Reconciliation (process toresolve differences)

not addressed

Equivalent
Convergence (process to establish equivalent requirements)

What are the Benefits ofHarmonization?
• Ensure more consistent regulatory positions
worldwide when performing safety reviews ofnew-reactor designs• Enable more efficient design reviews anddecision-making by regulators• Enhanced communications amongst regulators

Consistency in worldwide safety andreliability of NPPs

Example of Harmonization inRegulatory Reviews• EPR (Finland) undocumented weld repairs of main
coolant loop piping• Regulators from Finland, France, United Kingdom,and United States discussed and compared eachcountry’s regulatory practices and construction
code requirements for documenting weld repairs• Collaboration helped Finnish regulator reach asafety decision consistent with the significance ofdeviations and other countries’ regulatory practices

How Can We Achieve
Harmonization?
• Regulators play a minor role in harmonization ofpressure boundary code requirements• Need technical support of standards developingorganizations (SDOs) and vendors (CORDEL)** World Nuclear Association’s Working Group on
Cooperation in Reactor Design Evaluation and Licensing

Plan for Achieving Harmonization
1. Identify similarities and differences of code
requirements* (SDOs)
2. Select major code differences for convergence(CORDEL)
3. Converge on major code differences (CORDELand SDOs)
4. Minimize further divergence of code rules (SDOs)* Code comparison (ASME Report STP-NU-051-1) for Class 1
vessels, piping, pumps and valves is available at:
http://stllc.asme.org/News_Announcements.cfm

Step 1: Identify Code Differences• Standards Developing Organizations (SDOs) from
Canada, France, Japan, Korea, the RussianFederation, and U.S. initiated a code comparison• SDOs compared code rules for Class 1 vessels,piping, pumps and valves• Code comparison found varying degrees ofsimilarities and differences amongst codes• Results are documented in ASME Report STPNU-051-1 available at no charge for downloading:
http://stllc.asme.org/News_Announcements.cfm

Step 2: Select Code Differences• World Nuclear Association’s Working Groupon Cooperation in Reactor Design Evaluationand Licensing (CORDEL) established aCodes and Standards Task Force (CSTF)• CORDEL/CSTF sent a survey to nuclear
industry stakeholders and selected topics forharmonization• SDOs are also considering possible topics forharmonization

Step 3: Converge Code Differences• CORDEL/CSTF is pursuing convergenceof several technical topics including:– NDE personnel certification– Non-linear analysis methods• CORDEL/CSTF is planning to work with
the SDOs to develop consistent coderules in their respective codes

Step 4: Minimize Further Divergence• SDOs established a Convergence Boardin August 2012
• Meets 3-4 times/year in conjunction with
the ASME Boiler Code meetings• SDO Convergence Board’s charter is to:1) Limit divergence on individual requirements2) Achieve convergence on individual
requirements, where realistic and practical

Conclusions• Achieving harmonization of pressure-boundary
codes is a long and difficult process, in part,
because these codes are “living documents”• Even with their differences, each country’spressure-boundary code results in acceptably safe
components when used with that country’s
standard industry practice and regulations• Caution should be exercised when mixing code
requirements from different countries• Successful harmonization is strongly dependenton global cooperation and voluntary technicalsupport by SDOs and vendors (CORDEL)